JP4038204B2 - Video display device - Google Patents

Description

  The present invention relates to a video display device, and more particularly to a method for improving display quality in a video display device having a hold-type electro-optical conversion characteristic represented by, for example, a liquid crystal display device.

  A display typified by an LCD (Liquid Crystal Display) which has been widely used in recent years is widely used from a small mobile terminal to a large television.

  Unlike an CRT (CRT), an active matrix LCD or organic EL (electroluminescence) has an electro-optical conversion characteristic that, in principle, maintains the light emission luminance of the display screen for one frame of video display period. Such a light emission characteristic is called a hold type.

  Currently, there is a problem of image quality degradation of moving images due to blurring, tailing, and blurring due to the hold-type driving. Non-patent document 1 is an example of a document that describes LCD image quality degradation.

  As one of means for improving tailing in the LCD, there is a method of pseudo intermittent lighting (impulse type lighting) of light emission characteristics. For example, in “Liquid Crystal Display Device” of Patent Document 1, the backlight is turned on and off to make an impulse-type lighting, the liquid crystal display unit is illuminated, and the outline of the moving image is made clear. Further, “Display panel, driving method thereof and video projector” of Patent Document 2 proposes that the output of the lamp of the projector is shielded by a shutter to produce impulse light emission.

  Here, with reference to FIG. 61, the principle of occurrence of tailing resulting from hold-type driving will be described. In FIG. 61, in the LCD, a white object having a vertical length of 3 pixels and a horizontal length of an arbitrary size is displayed in a black background. It is a schematic diagram which shows the state which moves at constant speed at the speed of 1 pixel per flame | frame.

  In FIG. 61, (a) is the light emission waveform of the light source, where the vertical axis indicates the light emission luminance and the horizontal axis indicates the time. The light source is assumed to be a continuous light emission type whose light emission luminance is constant regardless of time.

  The part (b) in FIG. 61 is the outline of an object displayed on the LCD at a certain moment (the part of the area indicated by the vertical stripes in the part (c) in FIG. 61), and the horizontal axis indicates the space. The vertical axis indicates the transmittance. As shown in the part (b) in FIG. 61, the transmittance changes sharply with respect to the space.

  The part (c) in FIG. 61 is a schematic diagram showing how an object moves (the horizontal axis is time and the vertical axis is space). As time passes, objects are sequentially displayed in the cross-hatched part of FIG. 61 (c), and this part emits light with screen luminance determined by the transmittance of the pixels.

  Here, the object is moving in the direction of arrow 1 in part (c) in FIG. 61 with respect to the space axis. When the observer follows the eye while gazing at the moving object, the observer moves the line of sight in the direction of the arrow 2 and observes the object. Therefore, the luminance change along the arrow 2 is integrated (averaged) on the observer's retina. As a result, the object appears to the observer's eyes as shown in part (d) in FIG.

  That is, as shown in part (e) of FIG. 61, the center part of the object is displayed at a constant brightness to the eyes of the observer, but the brightness gradually decreases as it approaches the edge of the object. It looks like this. In FIG. 61 (e), the horizontal axis indicates space, and the vertical axis indicates luminance.

  As described above, tailing occurs in the moving image. That is, comparing the (b) part and (e) part of FIG. 61, it can be seen that the contour of the object visually recognized by the observer changes because the brightness near the edge is lowered. . The observer recognizes this inclination of luminance as image quality deterioration such as blurring, tailing, and blurring.

  Next, the principle of tail improvement by impulse light emission will be described with reference to FIG. FIG. 62 shows a state in which the moving object moves downward on the screen, as in FIG. In the impulse light emission, the light source emits blinking light as shown in FIG. 62 (a). Therefore, the brightness of the LCD is the product of the brightness of the light source and the transmittance of the pixels on the LCD panel, so that the brightness of the LCD screen can be obtained only during the period when the light source is on.

  Therefore, as shown in the part (c) in FIG. 62, the place where the cross hatching is applied to the object emits light. In the eyes of the observer, the luminance of the cross hatch portion is integrated, and the object appears as shown by the portion (d) in FIG.

62 (e) shows the luminance of the object shown in FIG. 62 (d). As shown in part (e) of FIG. 62, it can be seen that the brightness of the object visually recognized by the observer decreases as the edge of the object is approached. However, comparing the portion (e) of FIG. 62 with the portion (e) of FIG. 61, it can be seen that the luminance change shown in the portion (e) of FIG. 62 has a steeper slope. Therefore, it can be seen that the tailing (blurred outlines and rounding) is reduced by the impulse-type light emission.
JP-A-11-202285 (published July 30, 1999) Japanese Laid-Open Patent Publication No. 3-284791 (released on December 16, 1991) "Liquid crystal polishes video display, PDP competes with low power consumption", Nikkei Electronics, 11-18, p. 110, 2002

  However, in the above-described conventional technology, when the impulse-type display as described above is performed, image quality interference called flicker (flicker) occurs. This flicker disturbance has a significant adverse effect on the observer, such as causing eye strain. In particular, as the display quality of the LCD, such as an increase in screen brightness and an increase in screen size, is improved, this disturbance is easily recognized by an observer.

  Since the moving image tailing improvement and flicker interference reduction are in a trade-off relationship, the moving image tailing and flicker interference cannot be solved simultaneously. Hereinafter, this trade-off relationship will be described more specifically with reference to FIGS. 63 and 64.

  Each of FIGS. 63A, 63B, and 63C shows the light emission pulse waveform, the moving image tailing amount, and the flicker amount when the duty ratio is 25%. Similarly, FIGS. 63 (d), 63 (e), and 63 (f) show the light emission pulse waveform, moving image tailing amount, and flicker amount when the duty ratio is 50%. . Each of FIG. 63 (g), FIG. 63 (h), and FIG. 63 (i) shows the light emission pulse waveform, the moving image tailing amount, and the flicker amount when the duty ratio is 75%. The duty ratio is the ratio of the lighting period to the pulse period.

  The pulse waveforms in FIGS. 63A, 63D, and 63G show the lighting waveforms of the light source, and the light source is lit while these waveforms are High. In addition, between each duty ratio, the maximum brightness | luminance is adjusted so that the integrated value of emitted light brightness may correspond.

  63 (b), 63 (e), and 63 (h) show the amount of tailing when the tailing improvement by the impulse-type light emission described with reference to FIG. 62 is executed for each duty ratio. Show. In these figures, the steep slope of the luminance change means that the moving image quality improvement effect is large and the tailing (moving image blur) is small.

  63 (c), 63 (f), and 63 (i) show the flicker amount. The vertical axis represents the spectrum intensity with respect to the frequency, and the horizontal axis represents the frequency. The flicker amount is derived by performing Fourier transform on each pulse waveform of FIGS. 63A, 63D, and 63G and converting it to the frequency axis.

  For example, if the video signal input to the display device is an NTSC video signal, the pulse waveform is repeated at a period of 60 Hz, so the first harmonic after the Fourier transform operation is also 60 Hz. The larger the ratio of the first harmonic to the DC (direct current) component, the greater the flicker interference.

  As can be seen from FIG. 63, the trailing amount and the flicker amount are in a trade-off relationship. That is, if the duty ratio is increased in order to reduce the flicker amount, the amount of tailing increases although the flicker amount is reduced, and the moving image quality improvement effect is reduced. Conversely, if the duty ratio is reduced to reduce the amount of tailing, the amount of flicker will increase.

  FIG. 64A shows the relationship between the flicker amount and the duty ratio of the light source light emission pulse waveform. Here, the magnitude of the first harmonic of the pulse waveform with the duty ratio x can be expressed as a sampling function, that is, sin (x) ÷ x. Therefore, the flicker increases as the duty ratio decreases.

  FIG. 64B is a diagram showing the relationship between the amount of tailing and the duty ratio of the light source emission pulse waveform. Here, the amount of tailing is defined as the gradient of luminance change of the contour of the moving object when the moving object is visually recognized. As shown in FIG. 64B, the trailing amount is inversely proportional to the duty ratio x. Therefore, it can be said that the effect of improving the moving image quality increases as the duty ratio decreases.

  FIG. 65 is a diagram in which both of FIG. 64 (a) and FIG. 64 (b) are combined with the horizontal axis as the trailing amount and the vertical axis as the flicker amount. However, with regard to the amount of tailing, a threshold value of 15% to 85% is provided for the vertical axis of the waveform described in FIG. It is defined as the spatial extent of the tailing of.

  Also, in the curve of FIG. 65, the point where the trailing amount = 0.7 and the flicker amount = 0 is a characteristic of a general hold type LCD. When the conventional intermittent lighting technique is used, the value of the trailing amount and the amount of flicker moves on the curve of FIG. 65 according to the duty ratio. That is, as the duty ratio is reduced, the amount of tailing is reduced and the moving image characteristics are improved, but the amount of flicker is increased.

  As is clear from FIGS. 64 and 65, the relationship between the amount of tailing and the amount of flicker with respect to the duty ratio is a trade-off, so that it is not possible to solve moving image tailing and flicker interference simultaneously. However, if the curve can be moved in the direction of the white arrow in FIG. 65, it is possible to simultaneously improve moving image tailing and flicker interference.

The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a video display device that can simultaneously improve moving image tailing and flicker interference that are in a trade-off relationship.

According to a first aspect of the present application, in a video display device that displays video by modulating the luminance of a pixel based on a video signal, video display means for setting the transmittance of the pixel based on the video signal; Pulse-like emission intensity having the same frequency as the vertical synchronization signal, occupying D% of the vertical period of the video signal, and having an emission intensity of S1% of the emission intensity of the pixels displayed in the vertical period A first light source that emits intermittent light having a waveform of ## EQU2 ## and occupies all the time of the vertical period and has a light emission intensity of (100-S1)% of the light emission intensity of the pixels displayed within the vertical period. A second light source that emits light, illuminates the image display means with illumination light obtained by mixing the intermittent light and the continuous light, and sets the amount of tailing and flicker to S1 = 100's So as to reduce from the trailing amount and flicker amount in the mix, and controlling the light emission of the first light source body and the second light source body.

A second invention of the present application includes a first light source body driving unit that controls lighting / extinguishing of the first light source body, and a second light source body driving unit that controls lighting / extinction of the second light source body. and said that you are.

According to a third invention of the present application, the first light source body driving means switches at least one of power, current, and voltage supplied to the first light source body in synchronization with the video signal. It is characterized by that.

A fourth invention of the present application is characterized in that the second light source body driving means supplies at least one of electric power, current and voltage to the second light source body at a constant value. To do.

According to a fifth aspect of the present invention, at least one of the power, current, and voltage supplied by the second light source body driving means to the second light source body is a frequency that is at least three times the vertical frequency of the video signal. It is characterized by being controlled by .

In a sixth invention of the present application, the second light source body driving means controls at least one of power, current, and voltage supplied to the second light source body at a frequency of 150 Hz or more. It is characterized by.

The seventh invention of the present application is characterized in that the first light source body and the second light source body are semiconductor light emitting elements .

The eighth invention of the present application is characterized in that the semiconductor light emitting element is a light emitting diode .

The ninth invention of the present application is characterized in that the second light source body emits the continuous light by a light emission principle different from that of the first light source body .

The tenth invention of the present application is characterized in that at least one of the first light source body and the second light source body is a semiconductor light emitting element .

The eleventh invention of the present application is characterized in that the semiconductor light emitting element is a light emitting diode .

According to a twelfth aspect of the present invention, the second light source body is a cold cathode fluorescent lamp .

Since the video display device of the present invention obtains video display light by intermittent light and continuous light as described above, it is possible to achieve both improvement of moving image tailing and reduction of flicker interference. Here, flicker interference not only makes viewers uncomfortable, but also causes a reduction in attention and work efficiency and has an adverse effect on health such as eye fatigue. According to the video display device of the present invention, , Can prevent their adverse effects. Furthermore, reducing flicker interference is indispensable for improving the display quality of a video display device with a high brightness and a large screen. Thus, according to the present invention, it is possible to reduce flicker interference while improving moving image tailing, and to provide an optimal display quality for an observer.

  The present invention suppresses flicker interference by continuous light while improving image tailing (motion blur interference) by performing image display using intermittent light. Specifically, as shown in the following embodiments By forming an image with display light, it is possible to reduce the occurrence of both image quality interferences in a trade-off relationship. Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

Embodiment 1
FIG. 1 is a diagram showing a configuration of a video display device 1 according to an embodiment of the present invention. As shown in FIG. 1, the video display device 1 includes a display panel (video display means) 2, a video decoder 3, a column driver 4, a row driver 5, a column electrode 6, a row electrode 7, and an input terminal 9. .

  A video signal such as an NTSC video signal is input from the input terminal 9. The video decoder 3 performs demodulation processing corresponding to the input video signal, and outputs video data to the column driver 4 and a synchronization timing signal to the row driver 5.

  The column driver 4 supplies video data to the plurality of column electrodes 6. The row driver 5 sequentially selects a plurality of row electrodes 7 in accordance with the synchronization timing signal. For example, when paying attention to a certain row electrode, the row electrode selection time is 32 microseconds (= 1/60/525) if the synchronization timing signal period is 1/60 seconds and the number of row electrodes is 525. .

  At the intersection of the column electrode 6 and the row electrode 7. Pixel 8 is defined. The average light emission luminance of the pixel 8 is modulated and updated according to the video data supplied to the column electrode 6 during the selection period of the row electrode 7. On the other hand, during the time other than the selection period in which the average light emission luminance is modulated according to the video data, the pixel 8 holds the updated average light emission luminance. Further, the operation of maintaining the average light emission luminance of the pixel 8 is continued until the selection period in which the row electrode corresponding to the pixel 8 is next selected.

  A series of these operations are repeated for each vertical synchronizing signal of the video signal. Video display is performed by a set of pixels modulated and updated by these operations.

  FIG. 2 is a waveform showing a temporal response of instantaneous light emission luminance when attention is paid to a certain pixel. T is the vertical period of the video signal, and the unit is time. For example, in NTSC, T is 1/60 second. The pixel of the video display device of the present embodiment has a light emission time of D% with respect to the period T, a first light emission component that emits light with an intensity of S% with respect to the average light emission luminance of the pixel in one vertical period, Is (100-D)%, and a display image is formed by light composed of a second light-emitting component that emits light with an intensity of (100-S)% with respect to the average light emission luminance of the pixels in one vertical period.

Here, pixel light emission at a certain time is referred to as peak light emission value, light emission peak value, instantaneous light emission luminance, instantaneous light emission intensity, instantaneous light emission peak, or simply luminance. Strictly speaking, what is generally called luminance is instantaneous emission luminance, and the unit is [nit] (knit) or [cd / m ² ] (candelaper square meter). The human eye feels that the instantaneous light emission luminance is integrated and smoothed by the eye, and this is called average luminance, average screen luminance, screen luminance, average intensity, and average luminance level. Strictly speaking, the unit is not nit, but the unit of nit is often used equivalently. For example, in an LCD television, the average brightness when white is displayed is used for catalog specifications. As indicated by S in FIG. 2, the product of the instantaneous light emission luminance and the time ratio (or time) is called the light emission intensity ratio (or light emission intensity), the light emission component, and the light emission amount. In FIG. 2, the area surrounded by the vertical axis and the horizontal axis of the light emission waveform corresponds to the light emission intensity.

  That is, the first light emission component is indicated by an area with a slanting line on the left in FIG. Further, the second light emitting component is indicated by an area with a slanting line in the lower right in FIG. Further, the instantaneous light emission intensity of the first light emission component is larger than the instantaneous light emission intensity of the second light emission component.

  In this way, the viewer averages (integrates) the waveform shown in FIG. 2 and recognizes it as the luminance of a certain screen. The screen brightness of a normal video display device is defined by the screen brightness when white is displayed. For example, in the case of a video display device for television (TV) use, the screen luminance is set to 250 nit (nit is a unit of luminance), and when the screen is adjusted brightly, the screen luminance is set to 500 nit.

  FIG. 3A and FIG. 3B are diagrams showing an example of the light emission waveform of the pixel in the present embodiment. In these drawings, the light emission waveform for one vertical period is shown. FIG. 3A shows a light emission waveform of a certain pixel when the screen brightness is set to 450 nit. The first emission component has an instantaneous emission intensity of 900 nit and a duty ratio of 30%, and the second emission component has an instantaneous emission intensity of 260 nit and a duty ratio of 70%.

Therefore, the ratio of the emission intensity of the first emission component and the second emission component is
900 × 0.3: 260 × 0.7 = 6: 4.

  The luminance perceived by the human eye is an average value of the light emission intensity of the first light emission component and the second light emission component, and is thus calculated as 900 × 0.3 + 260 × 0.7 = 450 nit. Further, if a set of pixels having a luminance of 450 nit is the screen luminance, the luminance of the pixel is equal to the luminance of the screen, and the screen luminance is also 450 nit.

  FIG. 3B is a diagram showing the light emission waveform of the pixel when the screen brightness is set to 200 nit. The first emission component has an instantaneous emission intensity of 800 nit and a duty ratio set to 20%, and the second emission component has an instantaneous emission intensity of 50 nit and a duty ratio of 80%.

Therefore, the ratio of the emission intensity of the first emission component and the second emission component is
800 × 0.2: 50 × 0.8 = 8: 2.

  As described above, the video display device of the present embodiment is characterized in that it generates image display light composed of the first light emission component and the second light emission component in the pixel update repetition unit (vertical cycle). This characteristic configuration makes it possible to achieve both tail improvement and flicker interference reduction as will be described below.

  FIG. 4 is a diagram for qualitatively explaining the effect of the video display apparatus of the present embodiment. Specifically, in these drawings, a white object having a vertical length of 3 pixels and a horizontal length of an arbitrary size is displayed on a display panel in a black background. Shows a state in which the image moves downward at a constant speed at a rate of one pixel per frame.

  Part (a) of FIG. 4 is a diagram showing a temporal change in the instantaneous light emission intensity when attention is paid to a certain pixel, the vertical axis shows the instantaneous light emission intensity ratio, and the horizontal axis shows time. In FIG. 4A, the emission intensity corresponding to the first emission component is given vertical stripes, and the emission intensity corresponding to the second emission component is given a cross hatch.

  Part (b) of FIG. 4 shows the contour of an object displayed on the display panel 2 at a certain moment, with the horizontal axis representing pixels and the vertical axis representing relative levels. A relative level of 0% means black, and 100% means white. Also, part (c) of FIG. 4 shows how the object shown in part (b) of FIG. 4 moves (the horizontal axis is time, and the vertical axis is space).

  In addition, the display screen of the display panel 2 is originally a two-dimensional plane, but in the part (c) of FIG. 4, the description of one horizontal axis coordinate of the two spatial coordinate axes is omitted. As shown in part (c) of FIG. 4, the displayed object moves with the passage of time, and the brightness of the object has two types of intensity from the relationship between the movement and the light emission waveform of part (a) of FIG. 4. It is expressed in

  That is, as shown in part (a) of FIG. 4, since the instantaneous emission intensity increases during the period in which the first light emitting component emits light, as shown by the vertical stripe part in part (c) of FIG. 4, Instantaneous emission intensity also increases.

  When the observer follows the object along the arrow 2 along the line of sight, the object is shown in part (d) of FIG. It looks like this. FIG. 4 (e) shows the change in instantaneous luminance of the object shown in (d). In FIG. 4 (e), the horizontal axis indicates the space, and the vertical axis indicates the luminance ratio.

  As shown in part (e) of FIG. 4, according to the video display device 1 of the present embodiment, the luminance contour of the object recognized by the observer has three types of inclinations, that is, the inclination of the part (e) in FIG. 4. 1, slope 2, and slope 3. What is important here is that slope 1 and slope 3 shown in part (e) of FIG. 4 are gentle, while slope 2 is steep and has a steep slope.

  And the brightness | luminance change corresponding to the gentle inclination 1 and the inclination 3 is hard to be recognized with a human eye. This is because the contrast discrimination ability of an observer for a moving object is generally inferior to that of a normal stationary object. In other words, the human eye cannot recognize the contrast change of a moving object with a low contrast ratio. Therefore, it is not necessary to accurately display the contrast of the moving image up to the details of the image.

  Therefore, since the luminance contour of the object recognized by the observer is only the inclination 2, the moving image tailing when the pixel emits light (hold type display) at a constant luminance, as shown in FIG. 61 (e). On the other hand, the tail improvement can be sufficiently achieved.

  FIG. 5A to FIG. 5I are diagrams for quantitatively explaining the effect of the video display device of the present embodiment. The time response waveform of the luminance of the pixel, the tail, for each of the three types of light emission patterns. The drawing amount and flicker amount characteristics are shown.

  Here, FIGS. 5A to 5C show the characteristics of the emission luminance waveform, the amount of tailing, and the amount of flicker when a conventional impulse type emission pattern having a duty ratio of 25% is used. It is shown. FIGS. 5D to 5F show the characteristics of the emission luminance waveform, the amount of tailing, and the amount of flicker when an impulse-type emission pattern having a duty ratio of 40% is used. is there.

  5 (g) to 5 (i) show the characteristics of the emission luminance waveform, the amount of tailing, and the amount of flicker when the video display apparatus of this embodiment is used. Note that the duty ratio D of the first light emitting component in the video display device of the present embodiment was set to 20%, and the intensity ratio S of the first light emitting component to the entire light emission luminance was set to 80%.

  5 (a), 5 (d), and 5 (g) show the emission luminance waveform for each pattern. 5 (b), 5 (e), and 5 (h), each pattern was subjected to a light emission process for improving tailing by applying the tailing model described with reference to FIG. This is the amount of tailing.

  The spatial length when the luminance ratio of the waveform with respect to the tail space changes from 15% to 85% is defined as the tail amount. The threshold values defined as 15% and 85% are obtained by subjective evaluation experiments on the assumption that the sensitivity of the human eye is low with respect to the contrast of a moving object. In addition, the range shown by the arrow in FIG. 5B, FIG. 5E, and FIG.

  FIG. 5C, FIG. 5F, and FIG. 5I show the flicker amount for each pattern, and the luminance shown in FIG. 5A, FIG. 5D, and FIG. 5G. 2 shows the ratio of the zero-order DC component (average value) and the first-order harmonic component, each of which is frequency-transformed by Fourier transform. For example, when the vertical synchronization signal is an NTSC video signal of 60 Hz, the first harmonic is 60 Hz. In addition, flicker interference increases as the first-order harmonic component with respect to the zero-order DC component increases.

  Here, for each light emission pattern, the integrated value (that is, the average luminance) of the time distribution of the light emission luminance shown in FIGS. 5 (a), 5 (d), and 5 (g) is the same. Is set. Since the average luminance is the same in this way, the energy amount of each average value component (zero-order DC component) in FIG. 5C, FIG. 5F, and FIG. Since they are the same, it is possible to compare the amount of the first harmonic component for each light emission pattern.

  FIG. 6 collectively shows the characteristics of the respective light emission patterns of FIG. In FIG. 6, the duty ratio D of the first light emitting component in the first column indicates the ratio of the lighting time of the first light emitting component with respect to the vertical period. The emission intensity ratio S of the first emission in the second column is the ratio of the emission intensity of the first emission component to the entire emission luminance. The “emission intensity” here is a value obtained by integrating the instantaneous emission intensity with time.

  As shown in the light emission waveforms of FIG. 5A and FIG. 5D, the light emission pattern of the prior art uses a simple pulse light emission component. It can be said that the intensity ratio S of the light emitting components is 100%. Note that as described above, the first light emitting component and the second light emitting component emit light, which is a characteristic point of the video display device of the present embodiment.

  Further, the amount of tailing shown in the third column of FIG. 6 is calculated by the length of the arrow line shown in FIGS. 5B, 5E, and 5H, that is, the model defined in FIG. Is the spatial length of the tail. The flicker amount shown in the fourth column in FIG. 6 is a ratio of the 60 Hz component (first harmonic) to the average value (0th direct current component). Moreover, each of the 1st line-the 3rd line of FIG. 6 corresponds to the light emission patterns 1-3 of FIG.

  In the case of light emission without tailing countermeasures as described with reference to FIG. 61, the amount of tailing (the length of tailing in pixel units) is 0.7. On the other hand, in the conventional example shown in the first row of FIG. 6, the duty ratio is 25% and the trailing amount is improved to 0.18. That is, the amount of tailing is reduced by 75% compared to the case where no tailing countermeasure is taken. However, in the conventional example shown in the first row of FIG. 6, the 60 Hz harmonic component, which is the main cause of flicker, is generated at a rate of 90%.

  In the conventional example of the second row, the duty ratio is increased to 40% in order to reduce the flicker amount. As a result, the 60 Hz component, which is the main cause of flicker, is reduced to 75%, but the trailing amount is increased to 0.28. That is, in the conventional impulse-type light emission in the second row, the amount of tailing is reduced by only 60% compared to the case where no countermeasure against tailing is taken.

  On the other hand, the third row shows the amount of tailing and flicker when the duty ratio D of the first light emitting component is 20% and the light emission intensity ratio S is 80%.

  As can be seen from FIG. 6, according to the video display device of the present embodiment, the flicker amount can be attenuated from 90% to 70% as compared with the conventional example of the first row, and the amount of tailing is Is 0.18, which is improved to the same extent as the conventional example in the first row. As described above, according to the present embodiment, flicker interference can be significantly reduced while sufficiently improving the tailing, and it is possible to provide the viewer with an optimal quality video.

  FIG. 7 shows the characteristics of the respective light emission patterns in FIG. 5. The horizontal axis is the amount of tailing, and the smaller the value, the higher the image quality. The vertical axis represents the amount of flicker. The smaller the numerical value, the smaller the flicker and the higher the image quality. In the conventional image display, by changing the duty ratio D, the values of the flicker amount and the tailing amount move on the locus in FIG. 7 and do not move in the ideal improvement direction indicated by the white arrow. That is, the amount of flicker and the amount of tailing are in a trade-off relationship, and both cannot be improved at the same time. However, it can be seen that the light emission display characteristics of the video display device of the present embodiment indicated by the circles in FIG. 7 are improved in both the amount of tailing and the amount of flicker compared to the prior art.

  8A to 8C show the relationship between the duty ratio D, the amount of tailing, and the amount of flicker when the light emission intensity ratio S is fixed at 70% or 90% in the video display apparatus of the present embodiment. Is shown. In addition, when the duty ratio D is equal to the light emission intensity ratio S, the light emission waveform becomes a direct current, which is excluded from FIGS. 8A to 8C. Further, when the duty ratio D> the emission intensity ratio S, the instantaneous emission intensity of the first emission component is smaller than the instantaneous emission intensity of the second emission component, and the effect of this embodiment will be described also in this case. It is excluded because it is not.

  As shown in FIGS. 8A to 8C, the duty ratio D <light emission intensity ratio S and the light emission intensity ratio is fixed at 70% or 90%, and the possible duty ratio D is used. When the trailing amount shown in the model 4 and the flicker amount shown in FIG. 5 are calculated, the characteristic shifts from the characteristic of the prior art to the lower left for all duty ratios D (FIG. 8 ( a)), it can be seen that the amount of tailing and the amount of flicker are simultaneously reduced by the video display device of this embodiment.

  FIG. 9A to FIG. 9C show the light emission intensity ratio S and the tail of the first light emission component when the duty ratio D is fixed at 10% or 70% in the video display device of this embodiment. This shows the relationship between the amount and the amount of flicker. As is apparent from FIGS. 9A to 9C, when the duty ratio D <the emission intensity ratio S and the duty ratio D is fixed at 10% or 70%, a certain emission intensity ratio (here 70%). ) To less than 100% of the emission intensity ratio S, the trailing amount shown in the model of FIG. 4 and the flicker amount shown in FIG. 5 are calculated, and the trailing amount and the flicker amount are simultaneously reduced. (See FIG. 9A).

  In FIGS. 9B and 9C, the emission intensity ratio S is set to 70% because the tailing amount and flicker amount are different depending on the combination of the specific emission intensity ratio S and the duty ratio D. This is because the simultaneous improvement effect may be lost. That is, among the slopes 1, 2, and 3 shown in FIG. 4E, the slopes of the slopes 1 and 3 increase depending on the combination of the emission intensity ratio S and the duty ratio D, and the amount of tailing increases. is there. Therefore, in this embodiment, the case where the emission intensity ratio S = 40% is excluded.

  FIGS. 10A to 10B show the relationship between the duty ratio D, the amount of tailing, and the amount of flicker when the light emission intensity ratio S is fixed at 40% in the video display device of this embodiment. It is. As shown in FIG. 10A, it can be seen that the tailing amount and the flicker amount are not simultaneously reduced under this condition.

  FIGS. 11A and 11B show the relationship between the duty ratio D, the trailing amount, and the flicker amount when the emission intensity ratio S is fixed at 60%. Under this condition, the duty ratio D may or may not be effective.

  When the characteristics of FIGS. 8 to 11 are summarized, the conditions of the duty ratio D and the emission intensity ratio S that can obtain the effect of the video display device of the present embodiment are as shown in FIG. In the graph of FIG. 12, the horizontal axis represents the duty ratio D, and the vertical axis represents the emission intensity ratio S. The duty ratio D and the light emission intensity ratio S that can obtain the effect of the video display device of this embodiment are 62% ≦ S% <100% and 0% <D% <100% and D% <S%. Condition A is satisfied, or Condition B where 48% <S% <62% and D ≦ (S−48) /0.23 is satisfied. In FIG. 12, a halftone dot is attached to a region satisfying the condition A, and a hatched line is attached to a region satisfying the condition B.

  Further, setting S to 100% means using the conventional intermittent light emission (impulse type display), and is not included in the conditions A and B. Furthermore, setting S = D means that the instantaneous light emission intensity of the first light emission component is equal to the instantaneous light emission intensity of the second light emission component, and is not included in the conditions A and B. Furthermore, setting S = 0% or D = 0% means that the first light-emitting component is not generated, and thus is not included in the conditions A and B. Further, D = 100% means that the second light-emitting component is not generated, and thus is not included in the conditions A and B.

  For the emission intensity ratio S satisfying the condition A, as described with reference to FIGS. 8A to 8C, the effect of simultaneously reducing the trailing amount and the flicker amount can be obtained for all possible duty ratios D. Can do. Note that the range not included in the conditions A and B does not have the effect of simultaneously reducing the trailing amount and the flicker amount as described with reference to FIG.

  Further, as described in FIGS. 11A and 11B, the range of the emission intensity ratio S indicated by the condition B is the effect of simultaneously reducing the trailing amount and the flicker amount only when the duty ratio D is set. Can be obtained.

  FIGS. 13A and 13B show the relationship between the amount of tailing and the amount of flicker when the emission intensity ratio S = 62%. In this case, as shown in FIG. 13B, it can be seen that there is an effect of simultaneously reducing the trailing amount and the flicker amount with respect to the possible duty ratio D.

  FIGS. 14A and 14B show the relationship between the amount of tailing and the amount of flicker when the emission intensity ratio S = 48%. In this case, as shown in FIGS. 14 (a) and 14 (b), there is no duty ratio D that provides a simultaneous reduction effect of the trailing amount and the flicker amount. Thus, it can be seen from FIGS. 11, 13, and 14 that the emission intensity ratio S satisfying the condition B is 48 <S% <62.

  Further, FIG. 15B shows the upper limit of the duty ratio D that can achieve the simultaneous reduction effect of the trailing amount and the flicker amount in the range of 48 <S% <62, calculated by the trailing model and the flicker analysis. It is.

  That is, the duty ratio D and the light emission intensity ratio S calculated from the tailing model have values shown in FIG. This value is plotted in the graph of FIG. 15A as indicated by the asterisks in the figure. The characteristic indicated by the mark ◆ can be approximated to a straight line of approximately S = 0.23D + 48. If the duty ratio is smaller than the duty ratio indicated by the approximate straight line, the effect of simultaneously reducing the trailing amount and the flicker amount can be obtained. Therefore, as the condition B, D ≦ (S−48) /0.23 is set. Is done.

  FIGS. 16A to 16C illustrate the degree of improvement in tailing and flicker when six representative points are extracted for the emission intensity ratio S and the duty ratio D that satisfy the condition A or the condition B. FIG. It is a figure for doing. That is, in FIG. 16A, points P1 to P6 were extracted as satisfying the condition A or the condition B. In addition, the value of D and S in each point is shown in FIG.16 (b).

  FIG. 16C shows the tailing amount and the flicker amount obtained based on the model shown in FIG. 4 and plotted on the tailing amount-flicker amount graph. As shown in FIG. 16C, the values of the trailing amount and the flicker amount in P1 to P6 are shifted in the lower left direction from the intermittent lighting (impulse type display) line of the prior art. Therefore, if D and S are set so as to satisfy the condition A or the condition B, it can be said that both the image quality disturbances of the tailing and flicker are improved at the same time.

  If the relationship between the duty ratio D and the light emission intensity ratio S of the first light emission component and the second light emission component satisfies either of the above conditions A and B, the light emission waveform is as shown in FIG. The present invention is not limited to that shown in (a) or FIG.

  An example of such a light emission waveform is shown in FIGS. 17 (a) and 17 (b). In FIGS. 17A and 17B, the horizontal axis represents time, the vertical axis represents instantaneous light emission intensity, and the light emission waveform for one vertical period is shown. FIG. 17A shows a dimming function of the video display device (a function for switching the brightness of the entire screen by the user) and a control method of the video display device, and the frequency is about 2.4 KHz (16.7 milliseconds). This shows a case where a sawtooth wave that vibrates 40 times is superimposed. Even with such a light emission waveform, since the human eye does not follow the repetition frequency of 2.4 KHz, it is equivalent to the light emission waveform shown in FIG. 17B, and tailing and flicker, which are the effects of this embodiment, are achieved. The effect of improving at the same time is obtained.

  In FIG. 2 and FIG. 3 and the like, the waveform of the first light emission component and the second light emission component are described by rectangular waves in order to simplify the explanation of the time response waveform of the light emission of the pixel in this embodiment. However, the present invention is not limited to this rectangular wave. As described with reference to FIG. 4, in the hold type display device, there is a problem in that the human eye integrates the light emission of the pixel in a direction shifted from the original integration direction. The deviation in the integration direction and the integration path occurs to follow the moving object with the eyes. The conventional impulse display device reduces tailing interference by partially suppressing light emission, but this embodiment simultaneously improves the flicker amount while reducing the amount of tailing. The light emission waveform of this embodiment is achieved by concentrating the light emission intensity of the light emission intensity ratio S, that is, the so-called light emission energy, at the time specified by the duty ratio D. Therefore, it goes without saying that the effect is not reduced even if it is not a pure rectangular wave.

  18A and 18B show another example of the light emission waveform that can obtain the effect of improving tailing and flicker at the same time. As shown in FIG. 18A and FIG. 18B, the second light emission component may be composed of fine pulses. In FIGS. 18A and 18B, the horizontal axis represents time, the vertical axis represents instantaneous light emission intensity, and the light emission waveform for one vertical period is shown.

  Even when the emission waveforms shown in FIGS. 18A and 18B are used, the human eye does not follow the frequency of the second emission component as in the emission waveform shown in FIG. The light emission waveform of the second light emission component is equivalent to the light emission waveform indicated by the broken line, and improvement that achieves both tailing and flicker is possible. When adjusting the emission intensity ratio (100-S)% of the second emission component, the pulse lighting time T0 may be adjusted as shown in FIG. 18A, or FIG. 18B. As shown, the pulse intensity L0 may be changed.

  As the repetition frequency of the second light emitting component, a value that the human eye does not follow may be selected. For example, it may be several kiloHz like the frequency of the sawtooth wave in FIG. 17A, or may be several times the video vertical frequency of about 150 Hz. Further, depending on the characteristics of the displayed video of the video display device and the viewing environment, a frequency of 80 Hz may be used, or 100 Hz may be used. For example, in a video display device with a screen brightness of about 250 nits, the human eye may recognize continuous light even at about 120 Hz, that is, twice the frequency of the NTSC video signal. For example, in a video display device with a screen brightness of 500 nit, flicker may be felt at 120 Hz, and it may not be recognized as continuous light unless the frequency is 300 Hz or higher. When the video displayed by the video display device has many still images, a slight change in the luminance of the screen may appear as an obstacle, and when there are many moving image displays, there may be a case where a certain amount of screen fluctuation does not matter. In short, a frequency suitable for the system configuration of the video display device may be selected as appropriate.

  Further, FIG. 19 shows another example of a light emission waveform that can obtain the effect of improving tailing and flicker simultaneously. As shown in FIG. 19, the light emission waveforms of the first light emission component and the second light emission component may be triangular waves. In FIG. 19, the horizontal axis represents time, the vertical axis represents instantaneous light emission intensity, and the light emission waveform for one vertical period is shown. Such a triangular waveform can also be regarded as equivalent to the light emission response indicated by the broken line. That is, when the triangular light emission waveform as shown in FIG. 19 is applied to the model shown in FIG. 4, the slopes 1 and 3 in FIG. 2 is determined by the duty ratio D and the emission intensity ratio S of the first light emission component and the second light emission component, so that if the values of D and S satisfy the above-described condition A or condition B, the tail 2 It is possible to simultaneously improve both the image quality interference of pulling and flickering.

  FIG. 20 shows a case where the emission waveforms of the first emission component and the second emission component are exponential, and such an emission waveform is equivalent to the emission characteristic indicated by the broken line as in FIG. Thus, the effect of the present embodiment can be obtained.

  In the description of FIG. 2, the instantaneous light emission intensity of the first light emission component has been described as being larger than the instantaneous light emission intensity of the second light emission component. This is illustrated in FIG. 18A or FIG. This does not mean that the instantaneous emission intensity of the second emission component does not exceed the instantaneous emission intensity of the first emission component. In FIG. 18A and FIG. 18B, the second light emission component is equivalently replaced with a dotted line in consideration of the characteristics of the human eye, and the dotted line is based on the instantaneous light emission intensity of the first light emission component. It means small.

  In the above description, the definition of the tailing amount is a range of luminance change from 15% to 85%. Here, for example, when the screen brightness of the video display device is set to a bright value such as 600 nit or when the viewing environment is dark, the inclinations of the inclinations 1 and 3 described in the part (e) of FIG. Under the condition of the increasing duty ratio D and emission intensity ratio S, the observer may visually recognize the slopes 1 and 3, and the tail improvement effect may be reduced. In such a case, the light emission response waveform may be set within a range that satisfies the conditions of the duty ratio D and the light emission intensity ratio S shown in FIG.

  FIG. 21 shows the best duty ratio D and emission intensity ratio S in the present embodiment when it is assumed that the tail luminance level range to which the human eye responds is 10% to 90% (see FIG. 5). Is shown.

  In this case, D and S are conditions A1 where 79% ≦ S% <100% and 0% <D% <100% and D% <S%, or 69% <S% <79% and D ≦ (S -69) /0.127 is satisfied. In FIG. 21, the portion indicated by halftone dots is condition A1, and the portion indicated by diagonal lines is condition B1.

  FIGS. 22A to 22C show the relationship between the amount of tailing and the amount of flicker when the emission intensity ratio S = 69% and when S = 79%. As in the case where the conditions of D and S shown in FIG. 21 are set, it is assumed that the luminance level range of the tail to which the human eye responds is 10% to 90%.

  In this case, as shown in FIG. 22A, it can be seen that there is an effect of simultaneously reducing the trailing amount and the flicker amount with respect to the possible duty ratio D when S = 79%. Further, as shown in the figure, when S = 69%, there is no duty ratio D at which the effect of simultaneously reducing the trailing amount and the flicker amount is obtained. Thus, it can be seen from FIG. 22A that the emission intensity ratio S satisfying the condition B1 is 69% <S% <79%.

  23 (a) and 23 (b) show that 69% <S% <79% when the luminance level range of the tail to which the human eye responds is assumed to be 10% to 90%. In the range, the upper limit of the duty ratio D at which the effect of simultaneously reducing the tailing amount and the flicker amount is obtained is calculated by the tailing model and the flicker analysis.

  That is, the duty ratio D and the light emission intensity ratio S calculated from the tailing model have values shown in FIG. This value is plotted in the graph of FIG. 23A as indicated by the asterisks in the figure. The characteristic indicated by the mark can be approximated to a straight line of approximately S = 0.127D + 69. If the duty ratio is smaller than the duty ratio indicated by the approximate straight line, the effect of simultaneously reducing the trailing amount and the flicker amount can be obtained. Therefore, D ≦ (S−69) /0.127 is set as the condition B1. The

  FIG. 24 is a diagram for explaining the flicker reduction effect by the video display apparatus of the present embodiment based on the result of subjective evaluation. Regarding the screen brightness of the video display device, white brightness (screen brightness when white is displayed on the screen) was set to 450 nits. 450 nit is a level that is sufficiently bright as a television (TV) receiver, and nit (knit, nit) is a unit of luminance. Note that three types of images A, B, and C having different APL (Average Picture Level) were used as evaluation images. These images are still images.

  More specifically, the image A is an overall dark image such as a night view, for example, APL is 20%, and the average screen luminance is about 100 nit. Further, the image B is an image mainly composed of intermediate gradations with an APL of 50%, and the average screen luminance is 250 nits. The image C is a bright image such as a blue sky, APL is 80%, and the average screen luminance is 350 nit.

  These images A, B, and C are displayed on a video display device, and are switched between FIG. 5A, which is a light emission waveform in the prior art, and FIG. 5G, which is a light emission waveform in the present embodiment. It was driven to test whether or not image flicker can be perceived, and if it can be perceived, whether or not the image flicker can be disturbed. In addition, the scale of subjective evaluation was made into five steps. The larger the scale, the higher the image quality.

  As shown in FIG. 24, the subjective evaluation regarding the video display device of the present embodiment generally has a higher evaluation than the conventional technique. In the prior art, flicker interference becomes more prominent as the screen brightness increases. However, it can be seen that the flicker reduction effect by the video display device of the present embodiment has reached a level acceptable to the observer. This flicker reduction effect is similarly seen for three types of APLs, that is, three types of brightness images.

  As described above, the video display apparatus according to the present embodiment improves the tailing by using the low sensitivity of the human eye to the contrast of the moving object. Therefore, even if the brightness of the screen caused by the second light emitting component is visible to the human eye at a certain moment, it does not affect the tail improvement performance.

  As described above, in this embodiment, the emission response waveform including the first emission component and the second emission component suppresses the tailing of the moving object and displays a clear outline while simultaneously suppressing flicker interference. High quality image display can be realized. In order to improve the tailing of moving images, the low sensitivity of the human eye to the contrast of moving images is used.

  In addition, if the screen brightness of the video display device increases, flicker is easily perceived (Ferry-Porter's law). Therefore, when an image is displayed with high luminance by the conventional intermittent lighting method, flicker interference is likely to occur. In addition, since the human eye is more sensitive to blinking than the cone of photoreceptor cells, that is, the periphery of the visual field is more sensitive to flickering, flicker interference is easily recognized when the display panel in a video display device is enlarged. Become. Therefore, the video display device according to the present embodiment is particularly effective for improving the display quality of the video display device with high brightness or a large screen.

  Further, the conditions of the duty ratio D and the emission intensity ratio S described in FIG. 12 are calculated by replacing the trailing amount and the flicker amount with a simple model. The image quality of the video display device depends largely on the subjectivity of the observer and is also dependent on the viewing environment, so that it is difficult to accurately quantify it, but the inventors have conducted subjective evaluation experiments based on the conditions obtained (FIG. 24). (See)), it is confirmed that there is no significant difference between the conditions obtained by the model and the evaluation results.

  Further, the conditions of the duty ratio D and the emission intensity ratio S described in FIG. 12 are calculated by replacing the trailing amount and the flicker amount with a simple model. As a condition of the simple model, a white object is The amount of tailing when moving and the amount of flicker when displaying white are assumed. On the other hand, there is almost no 100% white signal in the video that is normally viewed. Therefore, when the average luminance level of the video actually displayed is about 50% with respect to the video display device having a screen luminance of 500 nit, for example, the screen luminance of the video display device is equivalently replaced with 250 nit (= 500/2). Thus, a method for obtaining the optimum values of the duty ratio D and the emission intensity ratio S is effective.

  In that case, the values of D and S may be determined from information such as a histogram (video data distribution) of the video to be displayed. Alternatively, a configuration may be adopted in which video feature quantities such as a luminance histogram and an average luminance level are automatically detected from the input video signal, and the light emission characteristics of the pixels can be automatically switched.

  Further, the flicker amount is determined by a 60 Hz component that is the first harmonic. In reality, a harmonic component that is an integral multiple of 60 Hz is generated, but the inventors have confirmed through experiments that only the 60 Hz component should be focused and suppressed. For example, there may occur a case where a harmonic of 120 Hz is recognized as interference for reasons such as an increase in screen size or brightness, but in this case as well, as described in the present embodiment, the light emission waveform is Fourier-transformed, What is necessary is just to obtain | require the conditions of duty ratio D and light emission intensity ratio S, paying attention to the quantity of both components of 60 Hz and 120 Hz.

  In the present embodiment, the video signal is described as NTSC. However, the video display apparatus of the present embodiment is also suitable for displaying a video signal of a personal computer, for example. For example, when the vertical frequency of the video display device is 75 Hz or the like, the flicker amount perceived by the observer is smaller because the sensitivity of the human eye is lower than that of 60 Hz. Observed as an obstruction. Also in this case, paying attention to the 75 Hz component, the conditions of the duty ratio D and the emission intensity ratio S may be obtained as in the present embodiment.

  Regarding the relationship between the duty ratio D and the emission intensity ratio S of the present embodiment, the case where the tailing is defined by the threshold values of 15% and 85% of the luminance change has been described with reference to FIG. Moreover, the case where it defined with the threshold value of 10% and 90% was demonstrated using FIG. However, the absolute threshold value is never uniquely determined. This is because the image quality of the video display device depends on the subjectivity of the observer. Or it changes also in viewing environment, such as ambient illuminance and viewing distance. Furthermore, it changes also in the point whether the image to display is a still image or a moving image. The point is that, among various applications of video display devices, an optimum value is determined each time, and qualitative and quantitative evaluation is performed using the method described in this embodiment, and finally, subjective evaluation is performed. Just do it.

  Further, the average luminance level of the display image may be detected, and parameters such as the duty ratio D, the emission intensity ratio S, and the emission phase of the first emission may be controlled dynamically or adaptively. These parameters may be controlled based on the histogram of the image. Motion information such as inter-frame differences may be used. Illuminance information may be obtained and controlled from an illuminance sensor that measures the illuminance around the video display device. Furthermore, you may use the information of those time fluctuations. The maximum value and the minimum value of luminance included in the video to be displayed may be used. The motion of the image may be detected as a vector, and control may be performed based on the information. In conjunction with the function of switching the screen brightness by the viewer, it may be controlled with a different parameter each time. The power consumption of the entire video display device may be detected, and parameters may be controlled to reduce power consumption. The parameter may be controlled so that the screen brightness is lowered when the continuous operation time from the power-on is detected and the lamp is lit for a long time.

  Furthermore, although the light emission waveform of the pixel in the present embodiment has been described using two types of light emission components, the first light emission component and the second light emission component, it is not particularly limited to two types. Depending on the modulation means of the pixel, an optimum characteristic may be obtained by separately defining the third light emission component and controlling it separately. The fourth light emitting component and the fifth light emitting component may be defined.

  In that case, in the model described with reference to FIG. 4, a waveform by light emission divided into a plurality of parts is set in part (a) of FIG. 4, and video information to be displayed is set in part (b) of FIG. If the information on the luminance change in the vertical direction of the part (c) is calculated and the integration calculation is performed in the direction of the arrow 2, the corresponding luminance change waveform of the tail is obtained. Even in the case of three or more types of light emission, it is possible to analyze using the model of the present embodiment, and it is possible to derive an optimum operating condition from the analysis result.

  Further, if an element that emits light from a pixel has a finite response time in time, information on the time response may be input to the portion (a) or (b) in FIG. They can be analyzed from the items described in the above-described embodiment, and an optimum operating condition can be derived.

  In the present embodiment, the amount of flicker is defined as the ratio of DC to the first harmonic in the Fourier transform result. Here, an absolute value may be introduced, and the harmonic ratio may be weighted for each absolute value. The absolute value corresponds to, for example, the average screen brightness of the video display device. If the screen brightness is bright, the allowable flicker amount decreases (becomes strict conditions) and changes depending on the average screen brightness. Therefore, if the ratio of DC to first harmonic is handled as a function of screen brightness, the accuracy of the flicker amount is further improved. Also, the flicker amount may be defined including the second harmonic.

[Embodiment 2]
A video display apparatus according to still another embodiment of the present invention will be described with reference to FIGS. FIG. 25 is a cross-sectional view of the video display apparatus according to the present embodiment. As shown in FIG. 25, the video display device 10 of this embodiment includes a light source (light source body) 11, a display panel (video display means) 12, a diffusion plate 13, and a chassis 14. Pixels (not shown) are defined on the display panel 12.

  In the video display device 10 having the above configuration, a space is formed between the diffusion plate 13 and the chassis 14, and the light source 11 is disposed below the space. The light source 11 emits illumination light toward the lower surface of the diffusion plate 13.

  The display panel 12 is a transmissive liquid crystal panel, for example, and modulates and transmits the illumination light that has passed through the diffusion plate 13. The illumination light is modulated according to the video signal to be displayed and is repeatedly performed according to the vertical synchronization signal of the video signal. Further, the light emitted from the display panel 12 to the upper surface is obtained by modulating the light of the light source 11 by the display panel 12, and the observer recognizes a set of light modulated for each pixel as a display image.

  FIG. 26 shows the relationship between the modulation waveform of the pixel (time change in the modulation rate of the pixel) and the light emission waveform of the light source 11 when attention is paid to a certain pixel. That is, data is written during the period when the vertical timing signal shown in part (a) of FIG. 26 is High, and the pixel modulation rates are D0 and D1 according to the video displayed as shown in part (b) of FIG. , D2. For example, in the NTSC video signal, this pixel modulation operation is repeated about every T = 1/60 seconds.

  Here, the response time characteristic of the pixel is ideal, and it is assumed that the response is completed within the writing time. The period in which the vertical timing signal is Low is a time when another pixel is selected, and the target pixel holds the written data.

  The light source 11 repeats at least two types of lighting modes in accordance with the vertical timing signal. That is, the part indicated by vertical stripes in part (c) of FIG. 26 is a first light emitting component having a duty ratio D% and a light emission intensity of S% with respect to the total light emission intensity. The portion indicated by cross hatching is a second light emission component having a duty ratio (100-D)% and a light emission intensity of (100-S)% with respect to the total light emission intensity.

  In the present embodiment, the light emission waveform shown in part (c) of FIG. 26 improves tailing (moving image blur) that occurs in principle in a hold type display device typified by a liquid crystal display device, and improves tailing. In this case, flicker interference generated as a harmful effect is also reduced.

  The reason why the tailing and flicker interference can be improved at the same time will be described with reference to FIG. FIG. 27 is the same model as FIG. 4. A white object having a vertical length of 3 pixels and a horizontal length of arbitrary size is displayed on a black background, and the object is displayed on the screen. A state of moving at a constant speed at a speed of one pixel per frame is shown in the downward direction.

  Part (a) of FIG. 27 is a diagram showing a temporal change in the light emission waveform of the light source 11. The vertical axis represents the instantaneous emission intensity ratio, and the horizontal axis represents time. In FIG. 27A, the emission intensity ratio corresponding to the first emission component is indicated by vertical stripes, and the emission intensity ratio corresponding to the second emission component is indicated by cross hatching.

  The part (b) in FIG. 27 shows the spatial response of the transmittance of a pixel when attention is paid to a certain pixel, where the horizontal axis indicates the pixel and the vertical axis indicates the transmittance. In addition, part (c) of FIG. 27 shows how the object shown in part (b) of FIG. 27 moves (the horizontal axis is time and the vertical axis is space).

  Although the display screen of the display panel 12 is a two-dimensional plane, in FIG. 27 (c), one horizontal axis coordinate is omitted from the two spatial coordinate axes. In addition, light emitted from the pixel is a product of light emission and transmittance of the light source. That is, as shown in part (c) of FIG. 27, the displayed object moves as time passes, and there are two types of brightness of the object based on the relationship between the movement and the light emission waveform of part (a) of FIG. It is expressed with the intensity of.

  That is, as shown in part (a) of FIG. 27, the emission intensity increases during the period in which the first light emitting component is lit. Therefore, as shown by the vertical stripe part in part (c) of FIG. The emission intensity of the is also increased.

  In the present embodiment, as shown in part (e) of FIG. 27, according to the video display device 10 of the present embodiment, the luminance contour of the object recognized by the observer has three types of inclinations, that is, ( e) The portion has slope 1, slope 2, and slope 3. What is important here is that slope 1 and slope 3 shown in part (e) of FIG. 27 are gentle, while slope 2 is steep and steep.

  And the brightness | luminance change corresponding to the gentle inclination 1 and the inclination 3 is hard to be recognized with a human eye. This is because the contrast discrimination ability of an observer for a moving object is generally inferior to that of a normal stationary object. In other words, the human eye cannot recognize the contrast change of a moving object with a low contrast ratio. Therefore, it is not necessary to accurately display the contrast of the moving image up to the details of the image.

  Therefore, since the luminance contour of the object recognized by the observer is only the inclination 2, the moving image tailing when the display panel is illuminated with the light source that emits light with a constant light emission intensity shown in the part (a) of FIG. On the other hand, the improvement of the tail disturbance can be sufficiently achieved.

  Here, the parameter of the time constant of the response characteristic of the liquid crystal is considered in the tailing model. Liquid crystals usually respond with a time constant on the order of milliseconds and cannot change instantaneously. In FIG. 27, the calculation was performed assuming that the time constant of the liquid crystal is 0 seconds.

Here, the response of the liquid crystal is approximated to an exponential function,
y = A0 * (1-exp (-t / τ)) (where y is transmittance, and A0 is an arbitrary constant)
And τ is a time constant, which is the time from the start of response to the response to about 63% of the final value. The time to reach 90% of the target transmittance is about 2.3 times the time constant. Here, a liquid crystal having a time constant of about 2 to 5 milliseconds is assumed. Liquid crystals with a slow response with a time constant of 10 milliseconds or more exist in the world, but are excluded here. The purpose of this embodiment is to improve the amount of tailing. As a premise for improving the tailing amount, it is necessary to combine both improvement of the hold type display characteristics and improvement of the liquid crystal response time. When hold-type light emission is improved for a liquid crystal with a slow response and irradiated with impulse-type light, interference such as edge breakage occurs. Therefore, here, the upper limit of the assumption of the time constant of the liquid crystal is 5 milliseconds.

  For example, when the time constant τ = 2.2 milliseconds (the time to reach 90% is 5 milliseconds), when an object with a length of 3 pixels is moving, attention is paid to a certain pixel. The change in transmittance is as shown in FIG.

  Further, the luminance change in the portion (c) of FIG. 27 corresponds to a value represented by an axis in the vertical direction with respect to the paper surface. The calculation of the luminance change with respect to space-time, that is, the calculation of the instantaneous emission intensity of the light transmitted from the pixel is performed by calculating the instantaneous emission intensity ratio of the light source shown in FIG. 27A and the pixel shown in FIG. And the time response of the pixel shown in FIG.

  When the calculation including the response characteristics of FIG. 28A is performed in this way, and the integration calculation is performed in the direction of the arrow 2 shown in the part (c) of FIG. ) And FIG. 28 (c). FIG. 28B shows a change in luminance that occurs at the edge in the traveling direction with respect to the movement of the object. FIG. 28C shows a luminance change that occurs at the rear edge with respect to the movement of the object.

  Here, in the light emission waveform of the light source 11 shown in part (a) of FIG. 27, the duty ratio D = 30% and the light emission intensity ratio S = 70%. As is apparent from a comparison between FIG. 28B and FIG. 28C and the portion (e) of FIG. 27, in the tailing calculation considering the time constant of the liquid crystal, the portions with the slopes 1 and 3 are straight lines. Disappear.

  However, since the inclination of this portion is gentle with respect to the inclination 2, the effect described in the first embodiment of the present invention, that is, the simultaneous improvement effect of the tailing and flicker is not attenuated. Specifically, the trailing amount in FIGS. 28B and 28C is 0.32, and the flicker amount is 0.49. If this value is plotted in FIG. 65, it can be seen that both the tailing amount and the flicker amount can be improved with respect to the conventional intermittent light emission.

  Here, the phase of the first light emitting component with respect to the response of the liquid crystal is as shown in FIG. The horizontal axis in FIG. 29 represents time with the vertical period of video display as one unit, and in the case of an NTSC video signal, the vertical period is 16.7 milliseconds. T1 is a time from when a response is started after a pixel is selected until the first light emitting component of the light source emits light, which is 8.1 milliseconds here. T2 is the time from when the pixel is selected until the first light emission ends, and is approximately 13.1 milliseconds.

  In the conventional intermittent lighting, the intermittent component is generally turned on after waiting for the response of the liquid crystal. Therefore, if the conventional intermittent lighting is represented as shown in FIG. 29, for example, T1 = 11.7 milliseconds and T2 = 16.7 milliseconds.

  However, in the present embodiment, as shown in FIG. 27E, the purpose is to make the balance of the slopes 1 and 3 and the slope 2 appropriate to make the tail inconspicuous. Therefore, the light emission phase of the first light emission component with respect to the pixel writing operation is determined by the time constant of the liquid crystal, and the phase is approximately from the center to the latter half of the response waveform of the liquid crystal (repetition timing of the refresh (rewrite) operation). It is preferable to set so that.

  FIG. 30A to FIG. 30C and FIG. 31 illustrate the effect of this embodiment in a light emission pattern with a duty ratio D = 30% and a light emission intensity ratio S = 70%. Here, as shown in FIG. 30A, the time constant τ = 3.5 milliseconds (the time to reach 90% is 8 milliseconds). Under this condition, calculation is performed using the model shown in FIG. In this case, as shown in FIG. 31, the phase of the first light-emitting component is such that the amount of tailing is minimum and the value is about 0 when T1 = 10.5 milliseconds and T2 = 15.6 milliseconds. .37 pixels.

  The tailing waveform for the space at this time is shown in FIGS. 30 (b) and 30 (c). Further, the amount of flicker at this time becomes 0.49 by Fourier transform of the time response waveform of light emission of the pixel. When the tailing amount 0.37 and the flicker amount 0.49 are plotted in FIG. 8A, it can be seen that the tailing amount and the flicker amount are simultaneously improved as compared with the prior art.

  In the present embodiment, a transmissive display panel is assumed as the display panel 12, but a reflective display panel may be used. In this case, the light source 11 may be disposed on the same side as the display surface of the display panel 12.

  In the present embodiment, the direct type backlight in which the light source 11 is arranged directly below the display panel 12 has been described. However, the backlight is generally suitable for a side edge type backlight. That is, the display panel 12 is illuminated by guiding the illumination light from the light source 11 disposed so as to face the side end surface of the light guide plate to the display panel 12 through the light guide plate made of acrylic or the like. May be.

  As described above, in the present embodiment, the light emission time response characteristics corresponding to the first light emission component and the second light emission component are realized by the light source, thereby improving both image quality interference between tailing and flicker. Can do. Here, as the light source 11, a semiconductor light emitting element such as a light emitting diode (LED), a cold cathode fluorescent lamp (CCFL), or the like can be used.

[Embodiment 3]
In the present embodiment, the case where the display panel in the video display device of the present invention is, for example, a self-luminous active matrix organic EL panel will be described.

  As shown in FIG. 32, the pixel 20 of the organic EL panel provided in the video display device of the present embodiment includes a selection TFT 21 for selecting each pixel, a capacitor 22, an EL element 23, and an electric current in the EL element 23. The EL driving TFT 24 and the luminance switching TFT 25 are configured to flow.

  The capacitor 22 connected to the drain of the selection TFT 21 is supplied with a voltage (or charge) corresponding to an image to be displayed from an external power source during the pixel selection period. The drain of the selection TFT 21 is connected to the gate of the EL drive TFT 24, and a current determined by the voltage charged in the capacitor 22 flows between the source and drain of the EL drive TFT 24 during the non-selection period.

  The drain of the EL drive TFT 24 is connected to the EL element 23, and when the drain current of the EL drive TFT 24 flows to the EL element 23, the EL element 23 emits light with a light emission intensity corresponding to the current.

  Further, the drain-source of the luminance switching TFT 25 is inserted between the gate of the EL drive TFT 24 and the ground. A scan electrode 26 is connected to the gate of the luminance switching TFT 25. Similarly, a scan electrode 27 is connected to the gate of the selection TFT 21.

  FIG. 33 shows a timing chart relating to the operation of the organic EL having the pixel shown in FIG. As shown in FIG. 33, the phase of the pulse of the scan electrode 26 is shifted by the duty ratio D with respect to the pulse of the scan electrode 27. Then, by turning on the luminance switching TFT 25 at the timing of the time delay of D%, the gate of the EL drive TFT 24 is grounded, and when the selection TFT 21 is on, the capacitor charged in the capacitor 22 is removed.

  Therefore, the gate potential of the EL drive TFT 24 is lowered accordingly, and the current flowing through the EL element 23 changes. As a result, the EL emission intensity changes, resulting in a light emission waveform as shown in part (c) of FIG. Here, the vertical axis of FIG. 33 (c) represents the instantaneous light emission intensity. Since this waveform is the same as that described with reference to FIG. 2, even when the organic EL is used as a display panel, both flicker and tailing amount can be improved.

  Further, the light emission intensity ratio S can be controlled to be a desired light emission intensity ratio by adjusting the charge amount of the capacitor 22 according to the time of the high period of the pulse of the scan electrode 26, for example. Alternatively, by providing a current limiting element in a path from the gate of the EL drive TFT 24 to the source-drain-switching TFT 25 to the source-drain-ground, the amount of charge flowing out from the capacitor 22 can be adjusted to achieve a desired emission intensity ratio. The voltage of 22 may be adjusted.

  The drain of the luminance switching TFT 25 is grounded, but may be connected to a negative power source, for example. As a result, when the charge of the capacitor 22 is removed, the charge transfer speed can be improved.

  Alternatively, the drain-source of the luminance switching TFT 25 may be connected to both ends of the capacitor 22 and the charge amount may be adjusted by short-circuiting both ends of the capacitor while the scan electrode 26 is High.

  In the above description, the display panel is an organic EL panel. For example, in a non-light-emitting transmissive liquid crystal panel, the data written in the pixels is controlled to modulate the illumination light from the light source. The light emission waveform of the pixel described in the first embodiment may be realized. In the case of a liquid crystal panel, a pixel is composed of a pixel selection TFT and a capacitor. By inserting a luminance switching TFT as in FIG. 32, the charge of the capacitor is controlled to change the transmittance of the liquid crystal. The brightness may be set, or the pixel selection TFT is accessed twice or more in one frame period (frame is a unit constituting the screen) without adding the brightness switching TFT, which corresponds to different brightness. You may make it write the data to perform.

[Embodiment 4]
A video display apparatus according to still another embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 34, the video display device 30 of this embodiment includes a display panel (video display means) 31, a controller 32, a column driver 33, a row driver 34, a light source controller 35, and a lamp (light source body, third light source body). ) 36, a shutter (light control means, shutter means) 37, a light guide plate (light mixing means) 38, and a shutter controller 39.

  In FIG. 34, the positions of the display panel 31 and the light guide plate 38 are shifted from each other, but they are actually used in a superimposed manner. A backlight in which a linear light source or a linear light source arranged in a line is input from the side end surface of the light guide plate 38, and the light guide plate 38 converts the input light into surface light emission to illuminate the display panel 31. The configuration of the light source is called a side edge type.

  The display panel 31 is, for example, a transmissive liquid crystal panel. On the display panel 31, a plurality of non-light emitting pixels (not shown) whose light transmittance is modulated according to an input video signal are arranged in a matrix. Is formed.

  The controller 32 outputs a video signal to the column driver 33, and the pixels are modulated by this video signal. Further, the controller 32 outputs a display timing signal to the row driver 34 and outputs a vertical synchronization signal 41 to the shutter controller 39. Further, the shutter controller 39 outputs a control signal 42 to control the shutter 37.

  The feature of the present embodiment is that the light that illuminates the display panel 31 is controlled using the shutter 37, thereby improving the tailing amount and the flicker amount simultaneously as described in the first and second embodiments of the present invention. In the point. In other words, the shutter 37 optically controls the output of the lamp 36. The shutter 37 transmits the illumination light of the lamp 36 at a rate of 100% or close to 100% during the time when the display panel 31 is illuminated with the first light emitting component.

  On the other hand, the shutter 37 semi-transmits the illumination light of the lamp 36 during the time when the display panel 31 is illuminated with the second light emission component. The transmissivity in the case of semi-transmission will be (100−S) / S * D / (100−D) if described with reference to FIG.

  FIG. 35 is a time chart for explaining the operation of the video display device 30 shown in FIG. 35A shows the signal waveform of the vertical synchronizing signal 41, FIG. 35B shows the time-change waveform of the transmittance of the shutter 37 controlled by the control signal 42, and FIG. 35C shows the portion of FIG. The light emission waveform of the lamp 36 with the instantaneous light emission intensity ratio taken on the vertical axis, and the portion (d) of FIG. 35 is the time response waveform of the illumination light passing through the shutter 37 with the instantaneous light emission intensity ratio taken on the vertical axis. The illumination light in part (d) of FIG. 35 illuminates the pixel via the light guide plate 38. The lamp 36 emits light with a certain luminance as shown in part (c) of FIG. Alternatively, the light emission waveform of the lamp 36 may be a waveform that fluctuates at a frequency at which the human eye does not respond as described with reference to FIG. 17, that is, a waveform that is recognized as a constant luminance by the characteristics of the human eye. .

  By controlling the transmission / semi-transmission of the shutter with the control signal 42 as shown in part (b) of FIG. 35, the illumination light for illuminating the pixels is changed from that shown in part (c) of FIG. d) Converted to the one shown in the part. Here, the transmissivity at the time of semi-transmission is about 30%, and the waveform in part (d) of FIG. 35 has a duty ratio D of the first light emission component of about 33% and a light emission intensity ratio S of about 60%. Corresponds to the case. The effect of the portion (d) in FIG. 35 is as described in the first embodiment. That is, as shown in part (d) of FIG. 35, the video display device 30 of the present embodiment also displays an image with the first light emission component and the second light emission component, so that tailing and flicker are improved at the same time. can do.

  The shutter 37 can be realized by, for example, a statically driven liquid crystal panel. Note that it is difficult for the optical shutter to have a transmittance of 0%, that is, a characteristic that completely blocks light, but the shutter 37 of the present embodiment does not completely block light, but it does not transmit illumination light. Therefore, various shutters can be used as well as optical shutters.

  In the present embodiment, the lamp 36 may emit light with a constant luminance, and it is not necessary to repeatedly turn on / off. Therefore, a light source body whose lifetime is shortened by an extinguishing operation such as CCFL can be used as a lamp. Moreover, since the lamp 36 emits light with a constant luminance, luminance unevenness hardly occurs and the light guide plate 38 can be easily designed.

  Further, since the lamp 36 is always lit, it is difficult for electrical stress to be applied to the light source controller 35, and a problem that the fuse malfunctions and blows is less likely to occur. Further, since the ripple current flowing through the electrolytic capacitor (not shown) inside the light source controller 35 is reduced, the reliability of the light source controller 35 is improved.

  In the video display device of the present embodiment, the shutter 37 is described as being mounted between the lamp 36 and the light guide plate 38, but the mounting position of the shutter 37 is not necessarily limited to this. For example, it goes without saying that the shutter 37 may be mounted between the light guide plate 38 and the display panel 31.

  Although the shutter 37 acts on all illumination light, for example, even when part of the illumination light enters the light guide plate 38 without passing through the shutter, the light can be used as illumination light. Therefore, the shutter 37 does not need to act on all illumination light.

  Further, the case where the shutter 37 is disposed between the lamp 36 and the light guide plate 38 and acts on the illumination light of the light source has been described. However, for example, the signal corresponds to the shutter for a video signal to be displayed by signal processing. Processing may be performed.

  For example, a multiplication circuit is provided in the video processing circuit, and the video signal is multiplied by a coefficient 1.0 during a period corresponding to intermittent light emission. That is, the video signal is passed as it is. On the other hand, the video signal is multiplied by a coefficient 0.3 during a period corresponding to continuous light emission. That is, the gradation luminance level of the video signal is compressed and output. In this case, the light source illuminates with constant continuous light emission. By such an operation, the screen luminance of the displayed video becomes equivalent to the portion (d) of FIG.

  Furthermore, the video display apparatus of the present embodiment can also be realized with the configuration shown in FIG. The same parts as those in FIG. 34 are denoted by the same reference numerals. As shown in FIG. 36, the shutter (light control means, shutter means) 43 is provided so as to partially block the illumination light from the lamp 36. That is, part of the illumination light from the lamp 36 is directly guided to the light guide plate 38 without being blocked or transmitted by the shutter 43.

  The shutter 43 transmits light from the lamp 36 at a rate of 0% when closed and 100% when opened. Further, the shutter 43 repeats transmission / reception with the waveform shown in part (b) of FIG. 35, and the lamp 36 emits light with a constant luminance as shown in part (c) of FIG.

  As described above, the shutter 43 intermittently repeats transmission / cutoff and acts on a part of the illumination light of the lamp 36, whereby the illumination light from the lamp 36 has a waveform shown in part (d) of FIG. The shutter 43 may be provided so as to block / transmit a part of the illumination light of the lamp 36, and a large shutter may not be used as the shutter 43. Strength can be improved. In FIG. 36, it is described that the individual light sources constituting the lamp 36 and the shutter 43 are provided in a one-to-one relationship, but it is not always necessary to provide them in this way. A configuration in which one shutter is provided for each of a plurality of individual light sources may be employed.

  Furthermore, since the video display device 30 of the present embodiment does not blink the lamp 36, a CCFL that is difficult to perform intermittent lighting operation from the viewpoint of reliability and life can be used as a light source. Of course, an LED may be used as the light source.

  Furthermore, although the blocking characteristic of the shutter 43 has been described as 0%, it may be a blocking characteristic of about 3%, for example. This is because the light transmitted through the shutter 43 can be used as illumination light. Therefore, the cutoff characteristic does not have to be strictly 0%.

  As described above, in this embodiment, the shutter 37 or 43 is used to generate time-responsive illumination light corresponding to the first light emission component and the second light emission component. Therefore, since the video display apparatus according to the present embodiment does not directly control the lamp 36, the lamp and the power source are not burdened. Furthermore, the video display device of the present embodiment can reduce flicker interference while displaying an object that moves with a clear outline while suppressing tailing, like the video display device of the first embodiment of the present invention. it can.

[Embodiment 5]
A video display apparatus according to still another embodiment of the present invention will be described below. As shown in FIG. 37, the video display device 50 of the present embodiment includes a display panel (video display means) 51, an intermittent light emitting device (light source body) 52, a continuous light emitting device (light source body) 53, and a timing generator. 54.

  The display panel 51 is configured by a non-light-emitting transmissive liquid crystal display that does not emit light itself and transmits and modulates illumination light from a light source, and receives a video signal 55.

  On the display panel 51, a plurality of pixels (not shown) that are modulated in accordance with the video signal 55 are formed in a matrix. This modulation operation is performed in synchronization with the vertical synchronization signal of the video signal 55. For example, when the video signal 55 is an NTSC video signal, the frame period (repetition period of the vertical synchronization signal) is 60 Hz.

  The timing generator 54 generates a vertical timing signal 56 synchronized with the vertical synchronization signal of the video signal 55 and outputs the vertical timing signal 56 to the intermittent light emitting device 52. The intermittent light emitting device 52 is a light source that performs a light emitting operation in synchronization with the vertical timing signal 56 and emits intermittent light emission 58 toward the display panel 51 as illumination light for illuminating the display panel 51. The intermittent light emission 58 is intermittent light in which the light emission intensity in the lighting state and the light emission intensity in the extinguishing state are indicated by a rectangular pulse waveform in synchronization with the vertical timing signal 56.

  The continuous light emitting device 53 is a light source that outputs continuous light emission (continuous light) 57 to the display panel 51 as illumination light for illuminating the display panel 51. The intensity of the continuous emission light 57 is constant irrespective of the vertical timing signal 56 or fluctuates at a frequency of, for example, 150 Hz or more of the repetition frequency of the vertical timing signal 56.

  The observer's eyes are very insensitive to light that repeatedly blinks at a frequency of about 150 Hz, and hardly react to light that repeatedly blinks at a frequency exceeding about 300 Hz. Therefore, strictly speaking, the continuous light 57 is recognized as light emitted at a constant intensity by human eyes even if it is light that fluctuates and blinks at a certain period.

  The pixels on the display panel 51 modulate the illumination light from the intermittent light emitting device 52 or the continuous light emitting device 53 according to the video signal 55. The illumination light modulated in this way is emitted from the display screen of the display panel 51 and recognized as a display image by the observer.

  FIG. 38 is a timing chart for explaining the operation of the video display device 50 of FIG. 37, and represents the time variation of the signal transmitted through each path and the light emission intensity. In FIG. 38, the horizontal axis indicates time and is described in units of frames of the video signal 55.

  The (a) part of FIG. 38 shows the signal waveform of the vertical synchronizing signal of the video signal 55. As shown in part (a) of FIG. 38, a rectangular wave is output for each frame as the vertical synchronization signal of the video signal 55. Further, part (b) of FIG. 38 shows the signal waveform of the vertical timing signal 56 output from the timing generator 54. As shown in part (b) of FIG. 38, the vertical timing signal 56 repeats on / off in synchronization with the vertical synchronization signal.

  In FIG. 38 (c), the vertical axis represents the instantaneous light emission intensity, and shows the temporal change in the instantaneous light emission intensity with respect to the continuous light emission 57 output from the continuous light emission device 53. As shown in part (c) of FIG. 38, the continuous light emission 57 is emitted regardless of the vertical synchronization signal.

  In FIG. 38 (d), the vertical axis indicates the instantaneous light emission intensity, and indicates the instantaneous light emission intensity of the intermittent light emission 58 output from the intermittent light emitting device 52. As shown in part (d) of FIG. 38, the intermittent light emitting device 52 blinks the intermittent light emission 58 in synchronization with the vertical synchronization signal. That is, the instantaneous emission intensity of the intermittent emission light 58 is such that the instantaneous emission intensity in the lighting state (about 0.7) and the instantaneous emission intensity in the extinguishing state (0) are repeated in synchronization with the video signal. A rectangular pulse with a sharp rise and fall is exhibited.

  The (e) part of FIG. 38 shows the transmittance of an arbitrary pixel determined from the video signal 55, and the vertical axis represents the transmittance. As shown in part (e) of FIG. 38, a white image is input to the pixels of the display panel 51 in a certain frame period (for example, between the first vertical period and the third vertical period). In the frame period (for example, the 0th period and the 4th period), black video is input.

  The sum of the instantaneous emission intensity of the continuous emission light 57 shown in part (c) of FIG. 38 and the instantaneous emission intensity of the intermittent emission light 58 shown in part (d) of FIG. 38 is shown in part (e) of FIG. The product obtained by multiplying the transmittance of the pixel is the luminance of the display image shown in part (f) of FIG.

  As described above, the video display device 50 according to the present embodiment is characterized by illuminating the display panel 51 with illumination light having different characteristics of the intermittent emission light 58 and the continuous emission light 57, as shown in part (f) of FIG. There is to do. The effect is to achieve both tail improvement and flicker interference reduction as described in the first embodiment of the present invention.

  That is, the definitions of the first light-emitting component and the second light-emitting component described in the first embodiment of the present invention, the intermittent light-emitting component described in the present embodiment (the vertical stripe portion in FIG. 38 (f)), and the continuous light-emitting component. Although different from the definition of (cross-hatched part in FIG. 38 (f)), these can be converted as described below using FIG. 39 (a) and FIG. 39 (b). FIG. 39A shows the first light emission component and the second light emission component in the first embodiment, and FIG. 39B shows a mixture of the continuous light emission 57 and the intermittent light emission 58. It shows the intensity of light for one vertical period. In addition, a, b, and c in FIGS. 39A and 39B indicate luminance (instantaneous light emission intensity).

  As shown in FIG. 39 (b), S1 = c * D = (ab) * D%. Further, as shown in FIG. 39A, a = S / D and b = (100−S) / (100−D). Therefore, S1 = {S / D- (100-S) / (100-D)} * D. Therefore, if the conditions of the duty ratio D and the emission intensity ratio S described in the first embodiment are converted by this equation, S1 is obtained. The duty ratio D is the same as in the first embodiment.

  Thus, it can be said that the light obtained by mixing the continuous light emission 57 and the intermittent light emission 58 is substantially the same light as the light obtained by mixing the first light emission component and the second light emission component. In the video display device 50 of the present embodiment, light from the light source is composed of two components, continuous light 57 and intermittent light 58, and each component is driven to emit light with different characteristics. As a result, a drive circuit and a drive power supply can be provided exclusively for continuous light emission or intermittent light emission, and the circuit configuration can be simplified to reduce costs. Further, since each light emission can be controlled by a separate circuit, the reliability of the circuit can be improved.

  Further, for example, a case where an LED is employed as the light source is assumed. Some commercially available LEDs have a low absolute maximum rated current during continuous lighting and a low instantaneous maximum rated current during pulse lighting. In the video display device 50 according to the present embodiment, LEDs for continuous light emission and intermittent light emission can be selectively used depending on the electrical characteristics of the LEDs.

  It is also possible to employ an LED for intermittent light emission and a cold cathode fluorescent lamp (CCFL) for continuous light emission. The LED has a high light emission response, and the cold cathode tube is a light source suitable for continuous lighting. In consideration of such characteristics of the light source, the light source may be selected and mounted on the video display device.

  As described above, in the present embodiment, light emitted from the continuous light emitting device 53 and the intermittent light emitting device 52 is mixed and irradiated to the display panel 51, thereby suppressing the tailing of the moving object and displaying a clear outline. In addition, it is possible to realize an image display in which flicker interference is suppressed. That is, by using a light source having characteristics suitable for continuous light emission and a light source having characteristics suitable for intermittent light emission, the light emission characteristics shown in FIG. 2 can be easily realized.

  In addition, if the brightness | luminance of the display panel 51 rises, flicker will become easy to perceive (Ferry-Porter's law). Therefore, if an image is displayed with high luminance, flicker interference is likely to occur. In addition, since the human eye is more sensitive to blinking than the cone of photoreceptor cells, that is, the periphery of the visual field is more sensitive to flickering, flicker interference is easily recognized when the display panel in a video display device is enlarged. Become. Therefore, the video display device 50 according to the present embodiment is particularly effective for improving the display quality of the video display device with high brightness or a large screen.

  The component of (100−S1)% that is the emission intensity ratio of the continuous emission light 57 may be at a level that can be easily visually recognized. In the impulse-type light emission of the prior art, when the same screen luminance is obtained by reducing the duty ratio, it is necessary to increase the instantaneous light emission luminance. In the case of a light source that cannot obtain a large instantaneous light emission luminance, the number of light sources to be used must be increased, leading to an increase in cost. If the number is not increased, the average screen brightness decreases.

  In the present embodiment, even when the continuous light emission 57 is visible, the tailing amount and the flicker amount can be improved at the same time, so that the instantaneous light emission luminance of the intermittent light emission 58 can be kept low. For example, in FIG. 3A, the instantaneous light emission luminance of the continuous light emission component is 260 nits. In FIG. 3B, the instantaneous light emission luminance of the continuous light emission component is 50 nit. The luminance of 250 nit or 50 nit is a level that can be sufficiently perceived by human eyes.

  Further, in the light emission of FIG. 3A, the light emission intensity ratio (100-S1)% of the continuous light emission component is 58%, and in FIG. 3A, the screen brightness is assumed to be 450 nits, so (100-S1 ) = 260. This strength can be easily visually recognized. In FIG. 3B, (100−S1) = 25%, and in FIG. 3B, the average screen luminance is assumed to be 200 nits, so the emission intensity is (100−S1) = 50. The light emission intensity of 50 is the brightness at which light is emitted dimly, but is visible.

  In the present embodiment, the display panel 51 of FIG. 37 is described as a non-light-emitting transmission type, but the present invention is also applied to a non-light-emitting reflection type display panel that modulates light by reflecting light emitted from a light source. It is possible to apply a lighting method similar to that of the video display device 50 of the embodiment.

  In addition, for a self-luminous hold drive display such as an organic EL, the same operation as that of the intermittent light-emitting device 52 and the continuous light-emitting device 53 of FIG. can do.

  Further, in the present embodiment, the case where the vertical synchronization signal of the video signal is an NTSC video signal of 60 Hz has been described, but the intermittent light emission of the present embodiment is also applied to a 75 Hz video signal such as an RGB video signal of a personal computer. It is possible to apply an illumination method using the device 52 and the continuous light emitting device 53.

  Further, in the present embodiment, it has been described that the light emission emitted from the continuous light emitting device 53 is constant regardless of the vertical timing signal 56, but even if this light emission fluctuates independently of the vertical timing signal 56, It is possible to apply to the embodiment. When there is a light source control circuit that performs dimming (brightness adjustment) of the light source by, for example, 500 Hz PWM (pulse width modulation), such a light source and its control circuit are also used in the continuous light emitting device 53 of the present embodiment. Can be adopted. This is because the human eye does not follow the frequency of 500 Hz, and it appears as if it is emitting light with a constant light emission intensity.

  In this embodiment, as shown in FIG. 38, in each frame period, the center of the vertical synchronizing signal of the video signal 55 shown in part (a) of FIG. 38 and intermittent light emission shown in part (d) of FIG. The center of the light emission phase of the light 58 coincides. As described above, it is preferable that the intermittent light emission 58 emits light at a phase that becomes the center with respect to the repetition timing of the refresh (rewrite) operation of the video signal. That is, the phase relationship indicated by each of the (a) part and (d) part of FIG. 38 is relative to the leading line of the video signal, that is, the video near the rising edge of the vertical synchronization signal of part (a) of FIG. This is a favorable state.

  Conventionally, the light emission timing with respect to the repetition timing of the video signal refresh operation (display data update operation) is such that, for example, the material constituting the pixel, such as a liquid crystal material, has an exponential function response with a time constant. It was supposed to match the period.

  However, in the present embodiment, among the inclination 1, inclination 2, and inclination 3 shown in part (e) of FIG. 4, the inclination 1 and inclination are utilized by utilizing the low dynamic contrast response for the observer's eyes. 3 is not recognized.

  The inclinations of the inclination 1 and the inclination 3 are determined by the phase of the intermittent light emission 58 with respect to the refresh operation of the video signal. Therefore, in order to prevent the observer from recognizing the inclination 1 and the inclination 3 in a balanced manner, the phase of the intermittent light emission 58 is centered with respect to the video signal rewrite repeated operation. That is, the pulse waveform of the emission intensity of the intermittent emission light 58 may be positioned at the center with respect to the pulse of the video signal.

[Embodiment 6]
A video display apparatus according to still another embodiment of the present invention will be described with reference to FIGS.

  FIG. 40 is a block diagram showing the configuration of a video display apparatus according to still another embodiment of the present invention. As shown in FIG. 40, the video display apparatus 60 includes a display panel (video display means) 61 and a video controller 62. , Data driver 63, scan driver 64, column electrode 65, row electrode 66, lamp driving circuit (first light source driving means) 67, lamp driving circuit (second light source driving means) 68, lamp (first light source) 69, a lamp (second light source body) 70, and a scene change detection circuit (scene change detection means) 77.

  On the display panel 61, a column electrode 65 arranged in a column shape and a row electrode 66 arranged in a row shape are arranged. The display panel 61 is a transmissive type that transmits and modulates illumination light from a light source. A plurality of pixels (not shown) are formed in a matrix at intersections between the column electrodes 65 and the row electrodes 66.

  The data driver 63 drives the pixel based on the data signal 72 and sets the transmittance of the pixel to a state determined by the data signal 72. The scan signal 73 has information on the horizontal synchronization signal and the vertical synchronization signal of the video signal 71. The horizontal synchronization signal is a display unit in the column direction (horizontal direction) of the display screen. The vertical synchronization signal is a display unit in the row direction (vertical direction) of the screen. The frequency of the vertical synchronizing signal is, for example, 60 Hz for an NTSC video signal.

  The scan driver 64 sequentially selects and scans the row electrodes 66 from the top to the bottom of the screen based on the timing of the horizontal synchronization signal of the scan signal 73. Further, the row electrode 66 to be selected is reset to the upper part of the screen based on the timing of the vertical synchronizing signal of the scan signal 73.

  When attention is paid to a certain pixel on the display panel 61, the cycle in which the pixel is selected is 16.7 milliseconds when the frequency of the vertical synchronization signal is 60 Hz. The video controller 62 generates a lamp control signal 74 based on the vertical synchronization signal of the video signal 71 and outputs it to the lamp driving circuit 67. The lamp driving circuit 67 controls the lamp 69 based on the lamp control signal 74. The light emission output of the lamp 69 is intermittent light emission (intermittent light emission component) 75 controlled by the lamp control signal 74. The lamp 69 can be realized by, for example, a single or a plurality of LEDs (light emitting diodes). Further, the intermittent light 75 illuminates the display panel 61.

  The lamp driving circuit 68 controls the lamp 70. The light emission output of the lamp 70 is continuous light emission (sustained light emission component) 76. The lamp 70 can be realized by a fluorescent lamp such as a single or a plurality of CCFLs (cold cathode fluorescent lamps). Alternatively, like the lamp 69, the lamp 70 can be realized by an LED. Similarly to the intermittent light emission 75, the continuous light emission 76 also illuminates the display panel 61. The intermittent light 75 and the continuous light 76 are mixed in a space from the lamps 69 and 70 to the display panel 61.

  The scene change detection circuit 77 determines the degree of scene change (change) of the display video, that is, the scene change amount (change amount) based on the video signal 71. The detected scene change signal 78 is output to the lamp driving circuit 67 and the lamp driving circuit 68.

  FIG. 41 is a timing chart for explaining the operation of the video display device 60 shown in FIG. 40, and represents a time change of a signal transmitted through each path and a light emission waveform. The horizontal axis is time, and the time axis is described in units of frames of the video signal 71. Here, the frame is a unit of the display screen of the video signal 71 and is determined by vertical synchronization.

  41A shows the signal waveform of the vertical synchronizing signal of the video signal 71. FIG. 41B shows a light emission waveform of the intermittent light emission 75, and intermittent light emission is performed in synchronization with the vertical synchronization signal. In FIG. 41 (b), the vertical axis represents the instantaneous light emission intensity.

  Part (c) of FIG. 41 is a light emission waveform of the continuous light emission 76 and emits light regardless of the vertical synchronization signal. The vertical axis | shaft of FIG.41 (c) is instantaneous light emission intensity. 41 (d) shows the waveform of the mixed illumination light. A light guide space in which the intermittent light emission 75 in FIG. 41 (c) and the continuous light emission 76 in FIG. 41 (d) reach the display panel 61. 2 shows the waveform of the light mixed in FIG.

  Here, the video display device 60 of the present embodiment is characterized in that the lamp drive circuits 67 and 68 are controlled by using the scene change detection circuit 77. A scene change is a temporal change of a video to be displayed in units of screen, and is an entire amount of movement of the screen. Even if the scene is not strictly switched, the case where the screen is panned, the case where a large object moves within a fixed screen, the case where the video changes in a large area within the screen, and the like are applicable.

  42A and 42B are examples of the scene change detection circuit 77. FIG. In FIG. 42 (a) and FIG. 42 (b), the slash and the numerical value written in the signal line indicate the bit width of the digital signal.

  In the scene change detection circuit 77 shown in FIG. 42 (a), an F (frame) memory 80 is used to make a difference between frames of the video signal 71 for each pixel, that is, a current signal of a pixel and a signal delayed by one frame. The difference is taken by the subtractor 81 to determine a scene change or a change or movement between screens.

  The signal from the subtractor 81 is passed through an ABS (absolute value) circuit 82, and then compared with a threshold value 84 by a comparator 83, thereby obtaining a 1-bit detection signal. This signal is added every other pixel by using a cyclic addition configuration composed of a latch circuit 85 and an adder 86 operating with a system clock.

  The cyclic addition signal generated in this manner is latched and determined by a latch circuit 87 that latches with the ramp control signal 74. This latching operation is performed for each vertical operation signal. That is, in this circuit configuration, the number of times that the inter-frame difference of pixels exceeds a certain threshold value in one screen unit is counted.

  The IIR (cyclic type) filter 88 uses the ramp control signal 74 synchronized with the vertical synchronization signal as a sampling clock. By passing the output of the latch circuit 87 through an IIR (cyclic type) filter 88, the filter is applied in the time axis direction. The IIR filter 88 outputs the scene change signal 78 generated in this way.

  For example, assuming that the scene change signal 78 has a 3-bit width and takes a level 7 when video signals having a large inter-frame difference are continuous, and a level 0 when video signals having a small inter-frame difference are continuous. A signal takes a large value when a difference between frames frequently occurs.

  Here, although it is assumed that the video signal 71 is 8 bits, since the comparator 83 uses 1 bit, the memory capacity can be reduced by setting it to about 4 bits at the stage of input to the F memory 80. For example, when an interlace signal is converted into a progressive signal, it is required to detect a difference between frames with high accuracy in order to perform general motion detection. In the case of the video display device 60 of the present embodiment, Since the inter-frame difference is detected in order to control the light emission amount of the light source that illuminates the entire screen or a part of the screen, it is rarely required to have such high accuracy.

  Further, it is not necessary to detect inter-frame differences for all data of the video signal 71, and for example, processing may be performed every other pixel. In this case, the memory capacity of the F memory 80 can be reduced. In addition, the operation speed (system clock frequency) of the detection circuit can be reduced. By adjusting the constant α of the IIR that is a recursive filter, it is possible to realize a light source control response that follows a steep change with respect to the time response of the change in the degree of scene change. It is also possible to make it. The constant α may be adjusted according to conditions such as screen brightness and the usage application of the video display device.

  For example, in the configuration of FIG. 42A, if α = 0.5, the transient response time by filtering (90% of the input signal after the change is output from the time when the input signal of the IIR filter changes). Is a time corresponding to approximately 5 screens (that is, 1/60 * 5 = 1/12 seconds). If α = 0.95, the transient response time is approximately 1 second.

  FIG. 42B shows the configuration of the scene change detection circuit 77 when determining the amount and degree of scene change based on the difference between frames of APL (average luminance level) in screen units (vertical synchronization units). It is a block diagram. The APL detection circuit 89 sequentially adds the data of the video signal 71 and then divides (average calculation). The D-FF (flip-flop) 90 latched by the ramp control signal 74 latches the APL calculated by the APL detection circuit 89 for each vertical period, and the difference is obtained by the subtractor 91.

  After the processing in the ABS (absolute value) circuit 92, the coring processing for noise countermeasure is performed in the coring circuit 93, and the scene change signal 78 is output. The coring is to apply a filter such as forcibly setting a minute value, for example, 0, 1, or 2, to 0 if a value of 0 to 15 is expressed by a 4-bit signal.

  In this way, the scene change detection signal is output from the coring circuit 93. As for the scene change signal, for example, when the difference in APL between frames is large, it is determined that the scene has changed greatly, and a level 15 signal is output. On the other hand, when the variation of APL is small, level 0 is output. With the configuration of FIG. 42B, the frame memory as shown in FIG. 42A can be omitted from the scene change detection circuit 77.

  FIG. 43 is a diagram schematically showing a light emission waveform for one vertical period with respect to illumination light for illuminating the display panel 61. This is a mixture of intermittent light emission 75 and continuous light emission 76 in a light guide space reaching, for example, the display panel 61. The intermittent emitted light 75 has a light emission time D%, a peak value of instantaneous light emission intensity a (nit), and a light emission intensity ratio S2%. In FIG. 43, vertical stripes are added to the emission intensity corresponding to the intermittent emission light. The continuous light emission 76 has a light emission time of T seconds, a peak value of instantaneous light emission intensity of b (nit), and a light emission intensity ratio (100-S2)%. In FIG. 43, the emission intensity corresponding to the continuous emission light is hatched.

  The term “light emission intensity ratio” is the ratio of the light emission intensity of continuous light emission or intermittent light emission to the average light emission luminance of the entire pixel within one vertical period. Note that the emission intensity of the intermittent emission light is obtained by calculating the difference (ab) between the peak value “a” of the instantaneous emission intensity of the continuous emission light and the peak value “b” of the instantaneous emission intensity of the continuous emission light at a duty ratio D%. It integrates with. The “luminescence intensity” is a value obtained by integrating the instantaneous emission intensity with time.

  The video display device 60 of the present embodiment is intended to improve the tailing amount and the flicker amount simultaneously, as in the first embodiment of the present invention. In order to achieve this object, the video display device 60 of the present embodiment illuminates the display panel 61 with illumination light having the waveform of FIG. The definition of the emission intensity ratio S described in the first embodiment and the emission intensity ratio S2 of FIG. 43 are different, but here, S2 = {S / D− (100−S) / (100−D)} * D. The light emission intensity ratio S2 may be converted into the light emission intensity S using the conversion formula, and the converted light emission intensity S may be adapted to the conditions A and B shown in FIG.

  44 (a) to 44 (c) are diagrams illustrating an example of a procedure for controlling illumination light that illuminates the display panel 61 using a scene change detection signal. In order to control the illumination light, the lamp driving circuits 67 and 68 are adaptively controlled by the scene change amount.

  Here, it is assumed that the greater the scene change amount, the greater the degree of scene change. In addition, the light emission intensity ratio S2 of the intermittent light emission 75 is fixed to 80%, and the setting of the duty ratio D is adaptively controlled by a scene change detection signal. Specifically, as shown in FIG. 44A, the duty ratio D is controlled to be reduced as the scene change detection amount increases.

  FIG. 44B is a diagram showing the characteristics of the tailing amount and the flicker amount when the duty ratio is controlled as shown in FIG. FIG. 44 (c) is data for obtaining the characteristics of FIG. 44 (b). Moreover, the area surrounded by a circle and the area surrounded by a square shown in FIGS. 44 (a) and 44 (b) correspond to each other.

  In this embodiment, when the amount of scene change is large, it is determined that the screen has a lot of movement, is large, or moves frequently, so the duty ratio of the area circled in FIG. 44A is used. When the duty ratio of the area surrounded by a circle is used, as shown in FIG. 44 (b), the amount of tailing decreases with respect to the area surrounded by a square, but the amount of flicker increases.

  When environmental conditions such as screen brightness, screen size, and ambient illuminance for viewing are determined, the amount of flicker that can be recognized by the viewer is determined, but the amount of flicker varies depending on whether the displayed screen is a movie or a still image. Tend. For example, in the case of a video display device for a personal computer, a still image is the center, and the allowable limit flicker amount is small. In other words, even a slight flicker is conspicuous. On the other hand, in the case of a moving image, a certain amount of flicker is not easily recognized by an observer, and flicker is not noticeable. Utilizing this characteristic, the tailing amount is ideally improved by reducing the tailing amount while increasing the flicker amount.

  Also, as shown in FIG. 44B, the characteristic between the tailing amount and the flicker amount in the video display device 60 of the present embodiment is located on the lower left side compared with the characteristic of the prior art. It can be said that the amount and the amount of flicker are improved at the same time.

  Here, when calculating the characteristics of FIG. 44B, the light emission intensity ratio S2 is fixed, so that the screen luminance does not vary with the duty ratio D. However, for example, the peak values a and b (see FIG. 43) of the instantaneous light emission intensity may be fixed values, and the duty ratio D may be controlled without setting S2 as a fixed value.

  In this case, the screen brightness varies by controlling the duty ratio D. However, by switching the duty ratio D in response to a scene change, it can be made inconspicuous even if the brightness varies at the screen change. Further, if the duty ratio D is lowered when the screen is moved or a scene change occurs, the screen brightness is lowered. Therefore, flicker is controlled in a less conspicuous direction, which is more advantageous for improving flicker interference.

  Further, for example, the control may be such that S2 is not set to a fixed value, and the peak value a is changed in conjunction with the duty ratio D. For example, assuming that the peak value b is a fixed value, the peak value a is 200 nits when the duty ratio D is 70% (that is, the emission intensity of the intermittent emission light 75 is equivalent to 140 nits), and 400 nits (intermittent emission light when the D = 50%. The peak value a is controlled so that the emission intensity of 75 is equivalent to 200 nits) and 900 nit (the emission intensity of the intermittent emission light 75 is equivalent to 270 nits) when D = 30%.

  When the peak value a is controlled in this way, when the movement occurs and the duty ratio D is reduced, S2 increases. On the other hand, in the case of still images and images with little movement, viewing a screen with high brightness for a long time leads to eye fatigue. Therefore, a clear moving image display can be realized by increasing the brightness and sharpening only when the screen moves or when there is a lot of movement. Further, the peak value b may be changed in conjunction with the duty ratio D. Further, the peak value a and the peak value b may be simultaneously changed in conjunction with the duty ratio D.

  45 (a) to 45 (d) show a case where the light emission intensity ratio S2 is controlled using a scene change detection signal. Here, it is assumed that the duty ratio D is fixed to 20% or 40%. Further, the emission intensity ratio S2 is changed by changing the peak value a or the peak value b. Since the emission intensity ratio of the continuous emission light 76 is (100−S2), it changes in conjunction with the control of the emission intensity ratio S2 of the intermittent emission light 75, and the screen luminance is kept constant.

  FIG. 45B is a diagram showing the relationship between the amount of tailing and the amount of flicker when the characteristics shown in FIG. 45A are used. 45 (c) and 45 (d) are data for obtaining the characteristics of FIG. 45 (b). In FIGS. 45A and 45B, the area surrounded by a circle and the area surrounded by a square correspond to each other in the drawings.

  When there is little motion on the screen, the control is performed in a direction in which the trailing amount is increased and the flicker amount is decreased by decreasing S2. For example, when the display image is centered on a still image as in the case of creating a document on a personal computer, flicker becomes conspicuous. Therefore, the amount of flicker can be reduced by reducing S2.

  Even when the still image is centered, movement occurs when the window is scrolled. Even in such a case, according to the video display apparatus of the present embodiment, video display can be performed with characteristics in which the amount of flicker and the amount of tailing are suppressed as compared with the characteristics of the prior art.

  Further, the duty ratio D, the peak value a, and the peak value b may be fixed and controlled so as to change the screen luminance, the emission intensity ratio S2, and either the peak value a or the peak value b, or You may control by making both link and changing a screen brightness | luminance.

  Furthermore, if the screen brightness is increased when displaying a moving image as opposed to displaying a still image, the sharpness of the moving image increases and the sharpness increases, and eye fatigue when viewing a still image can be avoided. On the other hand, if the luminance of the moving image is lowered, the flicker becomes inconspicuous and the improvement in the amount of tailing can be increased.

  For these controls, the optimum case may be selected depending on the application of the video display device (for example, for TV or PC). Alternatively, optimal control may be selected according to the characteristics of the lamps 69 and 70 selected in the mounting. For example, the LED light source can easily control the peak value of the instantaneous light emission intensity, but the cold cathode tube may be difficult to control the peak value of the instantaneous light emission intensity in relation to the ambient temperature. Therefore, it is preferable to employ an LED light source for the lamp 69 and control either or both of the duty ratio D and the peak value a. Further, it is preferable to employ a cold cathode tube light source for the lamp 70 and control other parameters with the peak b value as a fixed value.

  44 (a) to 44 (c) and FIGS. 45 (a) to 45 (d) illustrate the case where the duty ratio D and the emission intensity ratio S are controlled independently, the duty ratio D By simultaneously changing the emission intensity ratio S2, it is also possible to obtain the effect of simultaneously reducing the amount of tailing and flicker.

  46 (a) and 46 (b) show the duty ratio D or light emission intensity by using the APL information obtained from the scene change detection circuit 77 having the configuration shown in FIG. 42 (b) and the scene change amount in combination. The case where the ratio S2 is controlled is shown.

  For example, when the APL is low and the amount of motion is large, the duty ratio D may be reduced as shown in FIG. Alternatively, as shown in FIG. 46B, the emission intensity ratio S2 may be increased. Note that the duty ratio D and the emission intensity ratio S2 may be changed simultaneously. Thereby, for example, the bright spot of fireworks launched in the dark night sky can be displayed with emphasis by emitting light with higher brightness while improving the amount of tailing.

  When APL is high, flicker is more noticeable than when APL is low. Therefore, as shown in FIG. 46 (a), it is preferable that the decreasing rate of the duty ratio D is smaller than when the APL is low. Alternatively, as shown in FIG. 46B, it is preferable that the increase rate of the light emission intensity ratio S2 is increased as compared with the case where the APL is low.

  In particular, as shown in FIG. 46 (b), paying attention to the light emission intensity ratio S2, when the scene change amount is large, if the light emission intensity ratio S2 is increased more greatly when the APL is low, the observer's APL is increased. It is possible to improve the amount of tailing and flicker while utilizing the limit characteristic that feels flicker interference. The light emission intensity ratio S2 and the duty ratio D may be controlled independently of each other, or the duty ratio D and the light emission intensity ratio S2 may be controlled simultaneously by combining two characteristics.

  In this embodiment, the relationship between the duty ratio D and the light emission intensity ratio S converted from the light emission intensity ratio S2 is basically controlled under the conditions described in FIG. 12 of the first embodiment. However, for example, when there is little movement in the displayed video, that is, when the scene change signal described in FIGS. 42A and 42B is small, a value that deviates from the condition of FIG. 12, such as S = 40%, is adopted. May be. The reason is as follows.

  In FIG. 12, the threshold value of the luminance change of the trailing amount is set to 15% and 85%. Further, in FIG. 21, they are 10% and 90%. However, the absolute threshold value is never uniquely determined. This is because the image quality of the video display device depends on the subjectivity of the observer. Or it changes also in viewing environment, such as ambient illuminance and viewing distance. It also changes depending on the absolute value of screen brightness. Furthermore, it changes also in the point whether the image to display is a still image or a moving image. In the tailing model described with reference to FIG. 4, the amount of motion of the object is assumed to be equal to one pixel for the sake of simplicity of the model. That is, the amount of tailing is normalized by the moving speed.

  However, in practice, if the moving speed of the object is fast, the absolute value of the trailing amount also increases. If there is little movement in the display image, there may be no problem in display quality even if the threshold value of the trailing amount is increased. Therefore, when the threshold value of the trailing amount is viewed as a function of the amount of motion, there are cases where the display quality is optimal even with values of D and S that are out of the conditions of FIGS. In short, the optimum values of D and S based on the amount of motion may be derived from the simulation using the tailing model described in FIG. 4 and the subjective evaluation of the actual display image.

  In the video display device 60 of the present embodiment, the light source is not limited to the LED or the CCFL, and a light source suitable for intermittent light emission and continuous light emission may be appropriately employed. Furthermore, in the present embodiment, the display panel 61 in FIG. 40 is described as a transmission type, but a reflection type display panel that modulates light by reflecting light emitted from a light source may be used.

  As described above, in the video display device 60 of the present embodiment, the scene change detection circuit 77 detects the temporal change of the display video in units of screens, that is, the amount of motion, thereby improving the amount of tailing and flicker. Accuracy can be improved.

[Embodiment 7]
A video display apparatus according to still another embodiment of the present invention will be described with reference to FIG. As shown in FIG. 47, the video display device 100 of this embodiment includes a light source (light source body) 101, a light source (light source body) 102, a display panel (video display means) 103, a diffusion plate 104, and a chassis 105. ing.

  In the video display device 100 having the above configuration, a space is formed between the diffusion plate 104 and the chassis 105, and the light source 101 and the light source 102 are disposed below the space.

  Although these light sources 101 and 102 are comprised by LED, for example, you may be comprised by the other light emitting element. The light sources 101 and 102 emit illumination light toward the lower surface of the diffusion plate 104. The light source 101 emits intermittent light, and irradiates intermittent light 106 shown by a broken line.

  On the other hand, the light source 102 emits continuous light and emits continuous light 107 shown by a solid line. The display panel 103 is of a transmissive type, and transmits and modulates the illumination light that has passed through the diffusion plate 104. Further, the display panel 103 displays an image viewed by the observer on its upper surface.

  As shown in FIG. 47, two irradiation lights having different properties emitted from the light source 101 and the light source 102 diffuse in a spread determined by the directivity characteristics of the light source, and pass through the space between the diffusion plate 104 and the chassis 105. Mixed while passing.

  Therefore, the display panel 103 is illuminated with light obtained by combining the irradiation light of both the intermittent light emission 106 and the continuous light emission 107. As described in the fifth embodiment, by mixing these lights, an effect similar to that of the light composed of the first light-emitting component and the second light-emitting component (see FIG. 2) can be obtained. Therefore, the display panel 103 of the present embodiment performs the same operation as the display panel 2 in the video display device 1 of the first embodiment. Therefore, when displaying a moving object, the display panel 103 according to the present embodiment can display the object with a clear outline by reducing the amount of tailing, and can suppress flicker interference.

  As described above, in the video display apparatus 100 according to the present embodiment, illumination lights having different characteristics are mixed in a space from the light source to the display panel. For example, an LCD (Liquid Crystal Display) which is a non-light-emitting image display device includes a back lighting device (backlight) called a direct type as its light source. Its configuration is the same as that shown in FIG. Therefore, the video display device 100 of the present embodiment can be easily applied to an LCD having a direct type backlight.

  In general, a direct backlight in an LCD is used when the diagonal of the screen is 20 or more. In the large LCD, as described above, the observer can easily recognize the tailing disturbance, and when the conventional impulse type light emission is adopted in the large LCD, the flicker disturbance can be easily seen by the observer. Therefore, when the video display device 100 of this embodiment is applied to a large LCD, it is possible to provide an optimal display video with clear moving image display and no flicker interference.

  Also in a video display device that projects a display video onto a screen or the like, such as a projection liquid crystal projector, a light source that outputs intermittent light emission 106 and a light source that outputs continuous light emission 107 are prepared, and irradiation of both light sources is performed. If the liquid crystal panel is irradiated with light, the irradiation light of both light sources is mixed while reaching the liquid crystal panel, so that the effect of this embodiment can be obtained.

  In this embodiment, a transmissive display panel is assumed. However, the present invention can be applied to a reflective display panel. That is, when the liquid crystal panel of the present embodiment is applied to the reflective type, the light source is disposed on the same side as the display surface of the reflective display panel. If a light source that outputs intermittent light 106 and a light source that outputs continuous light 107 are prepared and the liquid crystal panel is irradiated with the light emitted from both light sources, the light emitted from both light sources reaches the liquid crystal panel. Since they are mixed, the image quality improvement effect by the video display device of this embodiment can be obtained.

[Embodiment 8]
A liquid crystal display device (LCD) according to another embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 48, the LCD 110 of this embodiment includes a liquid crystal panel (video display means) 111, a controller 112, a column driver (source driver) 113, a row driver (gate driver) 114, a power supply circuit (first light source body driving). Means, second light source body driving means) 115, lamp (second light source body) 116, lamp (first light source body) 117, light guide plate (light mixing means) 118, timing generation circuit (first light source body driving means) 119. , And a switch (first light source body driving means) 120.

  The lamp 116, the lamp 117, and the light guide plate 118 are collectively referred to as a backlight. Also, a linear light source as shown in FIG. 48 or a point light source arranged in a line is arranged so as to face the side end surface of the light guide plate 118, and the light emitted from the light source is used for surface light emission by the light guide plate 118. A light source configuration that converts and illuminates the display panel is called a side edge type. Note that the lamp 116 and the lamp 117 can be configured by LEDs, for example, but may be configured by other light emitting elements.

  On the liquid crystal panel 111, a plurality of non-light emitting pixels (not shown) whose light transmittance is modulated in accordance with an input video signal are formed in a matrix. The controller 112 outputs a video signal to the column driver 113, outputs a display timing signal to the row driver 114, and outputs a vertical synchronization signal 121 to the timing generation circuit 119. The timing generation circuit 119 outputs a control signal 122 via the switch 120.

  The LCD 110 according to the present embodiment is characterized in that illumination light having different light emission characteristics is mixed by using the light guide plate 118. That is, the LCD 110 of the present embodiment is characterized in that the light source is composed of two groups consisting of the lamp 116 and the lamp 117.

  The lamp 116 is directly supplied with power from the power supply circuit 115 via the power line 123. Therefore, the lamp 116 emits light regardless of the state of the control signal 122. On the other hand, power is supplied to the lamp 117 from the power supply circuit 115 via the power line 124 and the switch 120. The switch 120 is controlled by a control signal 122.

  The illumination light from the lamp 116 and the lamp 117 is incident from the side end face of the light guide plate 118. The light guide plate 118 guides the two illumination lights while mixing them. Specifically, the light guide plate 118 is printed with a pattern (not shown) for diffusing the illumination light, and diffuses the illumination light to guide the light to the liquid crystal panel 111.

  Further, the liquid crystal panel 111 modulates the illumination light from the light guide plate 118 by changing the transmittance of the pixels, and outputs it from the display surface. An observer observes the light emission of this display surface as a display image.

  FIG. 49 is a time chart showing the operation of the LCD 110 of FIG. 49A shows the signal waveform of the vertical synchronization signal 121. FIG. 49 shows a signal waveform of the control signal 122.

  49 (c) shows a waveform of power supplied from the power line 123, and the lamp 116 emits continuous light according to this waveform. 49 shows a waveform of power supplied from the power line 124, and the lamp 117 emits intermittent light according to this waveform. Further, part (e) of FIG. 49 shows the waveform of light output from the light guide plate 118, which is light obtained by combining light output from the lamp 116 and light output from the lamp 117.

  The LCD 110 of the present embodiment is characterized in that it has a plurality of light sources (lamp 116 and lamp 117) controlled by different driving principles, and the light emitted from both light sources is mixed by the light guide plate 118.

  The different driving principles mean pulse driving for generating a flash component controlled by a vertical synchronizing signal and linear driving for generating a sustained component not controlled by a vertical synchronizing signal. The lamp 116 that emits continuous light is controlled by linear driving, and the lamp 117 that emits intermittent light is controlled by pulse driving.

  In the LCD 110 of this embodiment, as shown in FIG. 49 (e), the liquid crystal panel 111 is illuminated with light in which intermittent light and continuous light are mixed. Therefore, the image quality described in the first embodiment of the present invention is described above. An improvement effect can be obtained.

  In the present embodiment, the type of the non-light emitting pixel is not limited. That is, even when the light guide plate 118 is disposed on the same side as the display surface of the liquid crystal panel and the illumination light output from the light guide plate 118 is reflected by the liquid crystal panel, the same effect as the LCD 110 of the present embodiment is obtained. It is done.

  The LCD 110 of this embodiment is configured so that the lamp 116 and the lamp 117 are aligned in FIG. 48, but it is not always necessary to align them.

  As described above, the LCD 110 according to the present embodiment uses the light guide plate 118 to mix intermittent light and continuous light having different characteristics to produce illumination light for the liquid crystal panel 111. Therefore, since the illumination light of the LCD 110 of the present embodiment includes a continuous light emission component and an intermittent light emission component, the video display device illuminated with the mixed illumination light clearly suppresses the tailing of the moving object. In addition to displaying the contour, the flicker interference can be reduced, so that a high-quality display image can be realized.

  In the LCD 110 of the present embodiment, the light sources are divided into two groups, and light emission is driven with different characteristics. As a result, a drive circuit and a drive power supply can be provided exclusively for continuous light emission or intermittent light emission, and the circuit configuration can be simplified to reduce costs. Further, since each light emission can be controlled by a separate circuit, the reliability of the circuit can be improved.

  Some commercially available LEDs have a low absolute maximum rated current during continuous lighting and a low instantaneous maximum rated current during pulse lighting. In the LCD 110 of the present embodiment, LEDs for continuous light emission and intermittent light emission can be selectively used depending on the electrical characteristics of the LEDs.

[Embodiment 9]
Still another embodiment of the present invention will be described with reference to FIG. 50, members having the same functions as those of the LCD of FIG. 48 are denoted by the same reference numerals.

  As shown in FIG. 50, the video display apparatus 200 according to the present embodiment includes a power circuit (first light source driving means) 201, a power circuit (second light source driving means) 202, a lamp (first light source body) 205, And a lamp (second light source body) 206.

  The video display apparatus 200 of the present embodiment has two power supply circuits 201 and 202, and the two lamps 205 and 206 are separately mounted. That is, the lamp 206 emits continuous light when supplied with power from the power supply circuit 202 via the power line 204. On the other hand, the output of the power supply circuit 201 is switched by the switch 120, and the output after switching is supplied to the lamp 205 via the power line 203. Thereby, the lamp 205 emits intermittent light.

  The feature of the video display apparatus 200 according to the present embodiment is that the lamp 205 and the lamp 206 that emit light based on different light emission principles are used. Specifically, the lamp 205 emits light with a waveform shown in part (d) of FIG. On the other hand, the lamp 206 emits light with the waveform shown in part (c) of FIG.

  Therefore, the power supply circuit 202 that supplies power to the lamp 206 always supplies constant power to the lamp 206, so that no stress due to load fluctuation is applied. On the other hand, since the power supply circuit 201 that supplies power to the lamp 205 is repeatedly turned on / off by the switch 120, load fluctuation occurs. Therefore, each of the power supply circuit 201 and the power supply circuit 202 can be optimized in accordance with the load characteristics of the supplied power. Specifically, power supply efficiency and circuit reliability can be improved.

  The lamp 206 can be constituted by, for example, CCFL (Cold Cathode fluorescent Light). The CCFL is not suitable for intermittent light emission because an excessive current flows at the moment of lighting, the discharge electrode deteriorates and the life is shortened. However, since the lamp 206 is always lit, it is possible to employ a light emitting element such as CCFL that is not suitable for an operation that frequently turns on and off.

  When light sources having different light emission principles are employed as the lamps 205 and 206, for example, the CCFL and the lamp 205 are employed as the lamp 206, the external shape, the mounting form, and the driving voltage are completely different. Therefore, as shown in FIG. 50, if each light source is mechanically separated as an independent block and mounted on the video display device, the mechanism design and insulation design are easy, and the heat dissipation is advantageous.

  Also, in the video display device 200 of the present embodiment, the light obtained by mixing the intermittent light and the continuous light is used as the illumination light, so that the same effect as that of the video display device described in the first embodiment of the present invention can be obtained. Can do. In other words, according to the video display apparatus 200 of the present embodiment, it is possible to suppress tailing that occurs when a moving object is displayed, and to reduce flicker interference while displaying the object with a clear outline.

  The video display device 200 of the present embodiment is described as using a side-edge type backlight using the light guide plate 118, but the direct type backlight described in the second embodiment of the present invention is used. Even in the video display device used, the same illumination method as that of the video display device 200 of the present embodiment can be applied.

  In addition, in the video display device 200 of the present embodiment, the lamp 205 and the lamp 206 are arranged on the end surfaces facing each other on the light guide plate 118 in FIG. 50, but it is not always necessary to arrange the lamps 205 and 206 in this way. .

  As described above, according to the video display apparatus 200 of the present embodiment, the moving object is displayed by using the light sources having different light emission principles and mixing the light from these light sources and irradiating the display panel. Flicker interference can be reduced while the moving object is displayed with a clear outline while suppressing the tailing that occurs at the time.

  In addition, since the video display device 200 of the present embodiment uses light sources having different light emission principles, the power supply circuit can be easily optimized. In addition, it has been difficult to adopt CCFL in the impulse-type light emission of the prior art in terms of reliability and life, but in the video display device 200 of this embodiment, CCFL is used as a light source that emits continuous light. it can.

[Embodiment 10]
A liquid crystal display (LCD) according to still another embodiment of the present invention will be described with reference to FIGS. 51, members having the same functions as those in FIG. 48 are denoted by the same reference numerals. As shown in FIG. 51, the LCD 400 of the present embodiment includes a power supply circuit 401, a lamp (light source body) 402, a timing generation circuit (intermittent optical signal generation means) 403, a reference voltage generation circuit (continuous optical signal generation means) 404, An adder circuit 405 and a power amplifier circuit 406 are included. The reference voltage generation circuit 404 includes, for example, a voltage dividing resistor and a voltage buffer.

  The LCD 400 according to the present embodiment does not include a lamp control switch, and the lamp 402 is configured by one type of light source, and the signals corresponding to the intermittent light emission component and the continuous light emission component are mixed electrically. It is characterized in that 402 is driven.

  FIG. 52 is a time chart for explaining the operation of the LCD 400 of the present embodiment. 52A is the waveform of the vertical synchronizing signal 121, FIG. 52B is the waveform of the control signal (intermittent optical signal) 407, and FIG. 52C is the control signal (sustained optical signal) 408. 52 (d) shows the waveform of the control signal (illumination light signal) 409, and FIG. 52 (e) shows the waveform of the power that causes the lamp 402 to emit light.

  Further, the control signal 407 output from the timing generation circuit 403 in FIG. 51 is not simply a binary logic signal for controlling on / off of the switch. That is, the control signal 407 is a digital multilevel signal that can represent a plurality of intermediate states or an analog signal that can represent continuous intermediate states.

  The reference voltage generation circuit 404 outputs a control signal 408 that is a reference voltage regardless of the vertical synchronization signal 121. This is also a digital multilevel signal or an analog signal. Further, the adder circuit 405 obtains the sum of the control signal 407 and the control signal 408. The sum of the two is output to the power amplifier circuit 406 as a control signal 409 indicating the light emission luminance of the lamp 402. The power amplifier circuit 406 outputs a part of the power supplied from the power supply circuit 401 to the lamp 402 as light emission power in response to the control signal 409.

  The LCD 400 according to this embodiment is characterized in that the lamp 402 is driven by electrically synthesizing respective electric signals corresponding to the continuous light emission component and the intermittent light emission component. Therefore, all the lamps 402 in FIG. 51 are turned on under the same conditions. Therefore, compared with the video display device described in the eighth and ninth embodiments, the LCD 400 according to the present embodiment has an advantage that uneven luminance is less likely to occur.

  In addition, the light source of the LCD 400 of the present embodiment has been described as a side edge type, but the same illumination method as that of the LCD 400 of the present embodiment can be applied to the direct light source described in the seventh embodiment. . Furthermore, in the present embodiment, the lamp is described as being composed of one type of light source, but a plurality of different types of light sources may be driven by an electrically mixed signal.

  Moreover, although the electrical signal corresponding to the continuous light emission component of the present embodiment has been described as having a smaller amplitude and continuous than the electrical signal corresponding to the intermittent light emission component, this need not necessarily be the case. That is, the electrical signal corresponding to the continuous light emission component may have the same amplitude as that of the electrical signal corresponding to the intermittent light emission component, and repeat on / off similarly to the electrical signal corresponding to the intermittent light emission component.

  The on / off operation of the signal corresponding to the continuous light emission component is either synchronized with the video signal or asynchronous, and the repetition frequency is about three times (for example, 150 Hz) or more of the vertical synchronization signal. It is also possible to realize a signal whose duration of the continuous light is extremely short, approximately 1/10 or less of the emission time of the intermittent light emission component.

  That is, a thin and many pulse signal may be used as a signal for obtaining a continuous light emission component. This is because the illumination light of the lamp controlled by such a signal is thin and many pulses are averaged, and it appears to human eyes as if it were continuously lit with low brightness. In this case, since the amplitudes of the electric signals corresponding to both intermittent light emission and continuous light emission are the same, a part of the circuit for emitting intermittent light and the part of the circuit for emitting continuous light can be shared. .

  As described above, in the present embodiment, the signals for controlling the illumination lights having different characteristics are combined in an electric circuit, so that the liquid crystal panel 111 is illuminated with the same illumination light as the light in which the illumination lights having different characteristics are mixed. Illuminate. Therefore, the effect of the image quality improvement by the LCD 400 of the present embodiment is the same as that of the video display device of the first embodiment of the present invention. That is, according to the LCD 400 of the present embodiment, flicker interference can be reduced while displaying a clear outline while suppressing the tailing of the object.

  Further, according to the LCD 400 of the present embodiment, since the lamp is configured by one type of light source, the optical system can be configured simply and easily designed. Furthermore, the LCD 400 of the present embodiment illuminates the liquid crystal panel 111 with the same type of light source, so that unevenness in brightness and color on the display screen are unlikely to occur.

[Embodiment 11]
With reference to FIGS. 53 to 55, description will be given of the simultaneous improvement effect of the trailing amount and the flicker amount by the light emission waveform using the pulses of two kinds of frequencies.

  53A shows a light emission waveform applicable to the pixel of the video display device of the present invention. A pulse A indicated by hatching corresponds to the first light emission component (see FIG. 2), and the duty ratio is D% and the light emission intensity ratio S3%.

  The feature of this embodiment is that the emission waveform corresponding to the second emission component is a set of pulses B indicated by halftone dots. Since the frequency of the pulse B (the reciprocal of t0 in the figure) is higher than the frequency of the video signal to be displayed, for example 150 Hz, and does not follow the human eye, the emission waveform shown in part (a) of FIG. Therefore, the emission waveform is the same as that shown in part (b) of FIG.

  Also, in part (a) of FIG. 53, four pulses B are generated at (100-D)% time, so the emission intensity of one pulse B is (100-S3) / 4%. . Further, the pulse A is synchronized with the vertical synchronization signal of the video signal, but the pulse B may or may not be synchronized with the vertical synchronization signal.

  FIG. 54 is a diagram for explaining the effect of reducing the amount of tailing when the light emission waveform shown in part (a) of FIG. 53 is used. FIG. 54 assumes that the tailing improvement is performed by adopting a non-light-emitting transmissive display panel such as a liquid crystal panel and setting the light emission waveform of the light source as shown in part (a) of FIG. is doing.

  FIG. 54 is the same as the model described in FIG. 4 and shows a state in which an object having a length of 3 pixels is moving in one direction of the screen at a constant speed of 1 pixel per frame. The product of the light emission waveform of the light source shown in part (a) of FIG. 54 and the transmittance of the pixel shown in part (b) of FIG. 54 is the luminance of the moving object shown in part (c) of FIG. In this state, assuming that the direction of the black arrow in the figure corresponds to the integration direction of the human eye, the integration calculation is performed in the direction of the black arrow. The result is the (d) part and (e) part of FIG.

  As shown in part (e) of FIG. 54, the luminance waveform of the moving object is composed of steps 1 and 3 and a slope 2. Since the steps 1 and 3 are difficult to identify with human visual acuity, the human eye mainly recognizes the inclination 2 as the tail of the object. Note that if the object is stationary, the steps 1 and 3 disappear, so that the steps are not perceived even with static vision. Therefore, even after the object stops, the backlight may continue to be lit with the same light emission waveform as before the stop.

  FIG. 55 shows the Fourier series calculation results of the light emission waveform shown in part (a) of FIG. 54 and the light emission waveform of the prior art. In FIG. 55A and FIG. 55B, both light emission luminances are set to be the same. If the luminance is the same, the DC direct current component when Fourier transformed is the same, and harmonics can be compared.

  As shown in FIG. 55 (c), the first harmonics of the light emission waveforms of this embodiment and the conventional example are 0.82 and 1.28, respectively. This embodiment means that flicker is reduced as compared with the conventional example.

  When this embodiment is realized by light emission control of a light source, a light source such as an LED may be employed. Since the LED emits light at a high speed with respect to the pulse-switched current, if the current waveform shown in part (a) of FIG. 53 is supplied to the LED, the LED emits light with a waveform similar to the current waveform. be able to. The current switch can be easily realized by a digital circuit.

  As described above, it is possible to reduce flicker while suppressing disturbance to the outline of the moving image, even by the light emission waveform shown in part (a) of FIG.

[Embodiment 12]
An image display apparatus according to another embodiment of the present invention will be described with reference to FIGS. In the video display device of this embodiment, the display panel is a self-luminous EL (electroluminescence) driven by an active matrix type. By supplying a current according to image information to an EL element arranged for each pixel, light intensity of light emission is controlled, and a display image is generated.

  FIG. 56 is a diagram showing a configuration of an EL pixel according to this embodiment. The EL pixel 601 includes a scan electrode 602, a signal electrode 603, a TFT 604, a capacitor 605, a TFT 606, a TFT 607, a TFT 608, an EL element 609, a power source 610, and a scan electrode 611. For example, in the case of an NTSC video signal, there are 525 scan electrodes 602 on the display panel. Since the NTSC video signal has a vertical frequency of 60 Hz and 525 scanning lines, the scan electrode 602 is selected every about 32 microseconds (= 1/60/525). The scan electrode is common to other pixels arranged in the horizontal direction of the display panel.

  Image information to be displayed is supplied from the signal electrode 603. For example, in the case of an NTSC video signal, there are 640 or 720 signal electrodes 603 on the display panel. The signal electrode 603 is common to other pixels arranged in the vertical direction of the display panel. When the scan electrode 602 of the target pixel is selected and a pulse is supplied, the TFT 604 is turned on. Since image information is supplied to the signal electrode 603 in accordance with this timing, this information is stored in the capacitor 605 in the form of voltage (or electric charge).

  When the target pixel enters the non-selection period, the TFT 604 is turned off and the voltage of the capacitor 605 is held. The EL element 609 emits light with a desired luminance by flowing a current determined by the voltage held in the capacitor 605 from the power source 610. Here, the EL pixel 601 of this embodiment has two systems for supplying current to the EL element 609. There are a system through the TFT 606 and a system through the TFT 607. The TFT 607 is controlled to be turned on / off by the TFT 608 controlled by the scan electrode 611.

  FIG. 57 is a diagram for explaining the operation of the EL pixel 601. The part (a) of FIG. 57 shows the waveform of a pulse signal supplied to the scan electrode 602. The repetition period T is 16.7 milliseconds (= 1/60) in the NTSC video signal. The part (b) in FIG. 57 shows the waveform of the pulse signal of the scan electrode 611. A portion (c) of FIG. 57 shows a waveform of a current flowing through the drain of the TFT 606. This current is supplied from the power source 610 and flows through the source-drain of the TFT 606 to the EL element. This current changes by turning on the TFT 604 while the scan electrode 602 is High and updating the voltage across the capacitor 605. It is assumed that the response of the EL element is faster than the response of a general liquid crystal, for example, and the scan electrode 602 changes to a desired current during the high period.

  As shown in part (c) of FIG. 57, a relatively large current I1 is set in a certain period, and the pixel emits light brightly. A small current I2 flows in the next cycle, and the EL element 609 emits light darkly. The other system is a current supplied from the power source 610 via the TFT 607. The amplitude of this current is determined by the voltage of the capacitor 605 as in the TFT 606 system. Therefore, in the portions (c) and (d) of FIG. 57, I1 = I3 and I2 = I4.

  However, the TFT 607 is different in that it is controlled by the scan electrode 611. The TFT 608 is turned on while the pulse of the scan electrode 611 is High. In this case, since the voltage between the gate and source of the TFT 607 is 0, the TFT 607 is off. While the scan electrode 611 is low, the TFT 608 is turned off. In this case, the TFT 607 is controlled by the voltage between the terminals of the capacitor 605, and a current flows as shown in part (d) of FIG.

  The waveform of the current flowing through the EL element 609 is as shown in part (e) of FIG. 57, which is the sum of the waveform shown in part (c) of FIG. 57 and the waveform shown in part (d). That is, I5 = I1, I6 = I1 + I3, I7 = I2, and I8 = I2 + I4.

  The EL element 609 emits light in accordance with the current waveform in part (e) of FIG. The light emission waveform depends on the current-light emission characteristics of the EL element. If the characteristics are proportional to each other, the light emission waveform is equivalent to the part (f) in FIG. By emitting light with this waveform, the effect of simultaneously improving the tailing amount and the flicker amount described with reference to FIG. 7 as Embodiment 1 of the present invention can be obtained.

  As described above, the video display device of the present embodiment is, for example, an active matrix driven self-luminous EL. Two TFTs controlled by a capacitor 605 storing video information are provided, and currents are supplied at different timings to generate light emission waveforms corresponding to intermittent light emission and continuous light emission. That is, the light emission of the pixel is composed of the first light emission component and the second light emission component described with reference to FIG. Or the light emission of a pixel is comprised from an intermittent light emission component and a continuous light emission component.

  The intermittent light emission phase P is controlled by the pulse phase management of the scan electrode 611. In addition, the intermittent light emission phase P means the ratio with respect to the period of time from the start of the vertical period to the center of the light emission waveform of the first light emission component or the intermittent light component. The phase of the first light emitting component may be controlled by the phase of the scan electrode 611. Also, the duty ratio D can be controlled by the low period of the scan electrode 611. In order to increase the light emission energy (that is, light emission intensity) of the intermittent light emission component or the first light emission component, the duty ratio D may be increased.

  Since the selection operation of the scan electrode 602 may be 1/60 second as in the conventional hold type light emitting EL device, it is not necessary to speed up the scan electrode driver (not shown) or the signal electrode driver (not shown). There is no need to perform clock rate conversion or the like using a frame memory or the like for storing a video signal externally. The number of capacitors may be one as in the conventional hold type light emitting EL device.

  FIG. 58 is a diagram for explaining another configuration example of the EL pixel. 58, parts equivalent to those in FIG. 56 are given the same reference numerals. An EL pixel 701 in FIG. 58 includes a capacitor 702, a capacitor 703, a TFT 704, a TFT 705, a TFT 706, a scan electrode 707, and a scan electrode 708. When the pixel is selected, the TFT 604 is turned on, and a voltage corresponding to the video information is written to the capacitor. This voltage is written to the series connection of the capacitor 702 and the capacitor 703.

  The TFT 705 and the TFT 706 are alternately turned on and off alternately, and the source-gate voltage of the TFT 704 is switched. When the TFT 705 is on, the voltage of the capacitor 703 becomes the source-gate voltage of the TFT 704, and when the TFT 706 is on, the sum of the voltages between the terminals of the capacitor 703 and the capacitor 702 becomes the source-gate voltage. The current of the EL element 609 is switched by these two gate voltages. The TFT 706 is controlled by the scan electrode 707. The TFT 705 is controlled by the scan electrode 708. An inverter may be provided in the pixel, and for example, a signal obtained by inverting the logic of the scan electrode 707 may be input to the gate of the TFT 705.

  FIG. 59 is a diagram for explaining the operation of the EL pixel 701. A portion (a) of FIG. 59 shows the amplitude of the pulse signal supplied to the scan electrode 602. 59B shows the amplitude of the pulse signal of the scan electrode 705, and FIG. 59C shows the amplitude of the pulse signal of the scan electrode 706. FIG. 59D shows the current amplitude of the EL element 609 controlled by the TFT 705. The TFT 705 is turned on while the scan electrode 708 is High, and the gate-source voltage of the TFT 704 is defined by the voltage across the capacitor 703.

This voltage is obtained by dividing the voltage written at the time of pixel selection by the capacitors 703 and 702. If the write voltage at the time of selection is V, and the capacitances of the capacitors 702 and 703 are C1 and C2, respectively, the voltage V2 across the capacitor 703 is
V2 = V * (C1 * C2 / C1 + C2)
It becomes.

FIG. 59E shows the current amplitude of the EL element 609 controlled by the TFT 706. The TFT 706 is turned on while the scan electrode 707 is High, and the gate-source voltage of the TFT 704 becomes the voltage V written at the time of pixel selection. V and V2 are V2 <V, and assuming that the gate-source voltage of the TFT 704 and the drain current of the TFT 704 are proportional, the currents I11 and I12 shown in the part (d) of FIG. e) Currents I13 and I14 shown in the part are:
I11 = I13 * (C1 * C2 / C1 + C2)
I12 = I14 * (C1 * C2 / C1 + C2)
It becomes the relationship.

  The portion (f) in FIG. 59 shows the waveform of the current that actually flows through the EL element 609, and is the sum of the waveform in the portion (d) and the waveform in the portion (e) in FIG. If the current-emission luminance characteristic of the EL element 609 is linear, the emission luminance waveform of the EL element 609 is a waveform shown in part (f) of FIG. That is, the light emission of the pixel is composed of the first light emission component and the second light emission component described in FIG. Or it is comprised from an intermittent light emission component and a continuous light emission component. With this waveform, it is possible to improve both the trailing amount and the flicker amount described in the first embodiment. The emission phase of the first emission component and the duty ratio D are controlled by the phase management of the pulses of the scan electrodes 707 and 708. When it is desired to increase the light emission energy (that is, the light emission intensity) of the first light emission component, it can be controlled by the capacitance ratio of the capacitors 702 and 703. Alternatively, the Low period of the scan electrode 707 may be increased and the High period of the scan electrode 708 may be decreased.

  As described above with reference to FIGS. 58 and 59, the video display apparatus according to another example of the present embodiment uses the video information stored in the capacitor in a divided state. Since the selection operation of the scan electrode 602 may be 1/60 second as in the conventional hold type light emitting EL device, it is not necessary to speed up the scan electrode driver (not shown) or the signal electrode driver (not shown). There is no need to perform clock rate conversion or the like using a frame memory or the like for storing a video signal externally.

[Embodiment 13]
A video display apparatus according to still another embodiment of the present invention will be described with reference to FIG. In the video display device of this embodiment, the display panel is an EL (electroluminescence) panel that emits light by active matrix driving, or a liquid crystal panel that does not emit light by active matrix driving. In this embodiment, by supplying a voltage corresponding to image information to an EL element or a liquid crystal element arranged for each pixel, the brightness of light emission is controlled and an image is generated.

  FIG. 60 is a diagram for explaining the operation timing of the video display apparatus according to the present embodiment. In order to simplify the description, it is assumed that the display panel has five scanning lines. The part (a) in FIG. 60 shows the waveform of the vertical synchronizing signal, which is a reference for screen repetition. In the case of an NTSC video signal, the frequency of the vertical synchronization signal is 60 Hz. The part (b) of FIG. 60 shows the waveform of the horizontal synchronizing signal. The scanning lines are assumed to be 5 lines, and 5 pulses from H11 to H15 are generated in one vertical period. The part (c) of FIG. 60 shows the waveform of the data signal, which is a signal supplied to one of the plurality of data electrodes arranged in the horizontal direction of the display panel.

  Here, the video display device of the present embodiment has a frame memory that separately stores video signals in units of frames, and by accessing the image data stored in the frame memory, the data in the time axis direction of the data can be obtained. Sort. Here, the pixel located at the top of the screen is designated as pixel 1 and the pixel located below is designated as pixel 2, so that numbers 1 to 5 are assigned to the pixels located on the same data electrode in the order of arrangement in the vertical direction. shake. The video data displayed on the pixel 1 is D1, and the video data displayed on the pixel 2 is D2. D11, D12, and D13 mean video data obtained by dividing D1 into three and rearranging them in the time direction.

  As shown in part (c) of FIG. 60, for example, in the case of data for pixel 1, the data arrangement is such that D11 occurs at the beginning of the H11 period, D12 occurs second in H13, and D13 occurs third in H14. Change. It is assumed that 100% level of white (255 levels at 8 bits) is input to D1 in a certain frame, and 60% level of gray (150 levels at 8 bits) is input to the next frame after 1/60 seconds.

  The division of the image data is determined by the duty ratio D and the emission intensity ratio S. For example, it is assumed that the duty ratio D = 50% and the light emission intensity ratio S = 80%. Further, it is assumed that the instantaneous peak luminance that can be emitted by the pixels of the video display device is 1000 nits. If the white signal is D1 = 100%, the instantaneous light emission luminance (the height of the vertical axis of the first light emission) described in FIG. 2 is 100%, which is 1000 nits. The second light emission has a light emission intensity ratio S of 20%, and the instantaneous light emission luminance (the height of the vertical axis of the second light emission) in FIG. 2 is 250 nits, which is 25%. The calculation is performed at 250 nit = 1000 nit * 50% / 80% * 20%. Numerical values of 50%, 80%, and 20% correspond to D, S, and (100-S) in FIG.

  Thus, D11, D12, and D13 are determined from D1 by calculation determined by the duty ratio D and the emission intensity ratio S. The video data is divided and set so that a 100% white signal emits light at an instantaneous light emission luminance of D11 = 25%, D12 = 100%, and D13 = 25%. Assuming that the video data and the light emission luminance are proportional, in other words, with 8-bit video data, the division of the 255 level white signal is D11 = 64 level, D12 = 255 level, and D13 = 64 level. From the instantaneous light emission luminance and the duty ratio of 50%, the average screen luminance is 1000 * 0.5 + 250 * 0.5 = 625 nit.

  In the case of the gray gradation of D1 = 60%, the value is 60% of that described for the white signal. That is, if D1 = 60%, D11 = 15%, D12 = 60%, and D13 = 15%. Assuming that the brightness corresponding to each of D11, D12, and D13 is L11, L12, and L13, if the 100% instantaneous light emission brightness is 1000 nits, then L11 = 150 nits, L12 = 600 nits, and L13 = 150 nits.

  The part (d) in FIG. 60 shows the waveform of a pulse signal applied to the scan electrode that scans the pixel 1. It is assumed that the pixel 1 is located at the upper part of the screen. Note that it is assumed that there are five scanning lines, and five pixels exist on the same data electrode. It is assumed that the video signal D1 is video data displayed on the pixel 1.

  The scan signal generates a pulse three times in one vertical period. This pulse is about 1/3 of the horizontal period. Further, the pulse generated three times in one vertical cycle is shifted in phase with respect to the horizontal synchronizing signal. The phase of the video data D11, D12, and D13 divided and rearranged in the time direction corresponds to the phase of the high period of the scan signal of the pixel 1. That is, the image data of the pixels 1 rearranged in the time direction is taken into the pixel 1 by the scan signal, thereby defining the light emission of the pixel 1.

  In the waveform of part (d) of FIG. 60, the first pulse from the left is located in the first half of the horizontal synchronizing signal, the second pulse is located in the middle, and the third pulse is located in the second half. ing. A portion (e) in FIG. 60 is a light emission waveform of the pixel 1. The vertical axis represents luminance. Assume that D1 = 100% (255 level) white signal. During the first High period of the scan signal, the pixel 1 is set to L11 which is a light emission state (light emission luminance) determined by D11. The instantaneous light emission luminance at this time is 250 nits in the above example. Since the data of D11 is held when the scan signal falls to Low, the pixel 1 continues to emit light at 250 nits. Next, D12 is written as the pixel data of the pixel 1 in the second High period. In the above example, L12 = 1000 nit.

  Since the scan signal falls to Low again, D12 is held, and the pixel 1 continues to emit light at 1000 nits. Similarly, L13 = 250 nit corresponding to D13 is written and held in the third scan pulse. That is, in the present embodiment, the light emission luminance corresponding to the video data of the data signal of (c) part of FIG. 60 is set in accordance with the timing when the scan signal of (d) part of FIG. 60 is High.

  For example, in the case of an EL element, video data is held as a capacitor voltage, and a current corresponding to the voltage is passed through the EL element to emit light. In the case of a liquid crystal element, video data is held as a charge, and the liquid crystal is modulated so as to have a transmittance corresponding to the charge.

  L11, L12, and L13 in part (c) of FIG. 60 are, for example, L11 = L13 and L12> L11. By emitting light with this waveform, the effect of simultaneously improving the tailing amount and the flicker amount described in FIG. 7 of the first embodiment can be obtained. The duty ratio D of the first light emission component described in FIG. 2 is determined by the rearrangement of the data signals and the pulse phase of the corresponding scan signal. The emission intensity ratio S is determined by the division method (ratio) of video data division of D11, D12, and D13.

  Parts (f) and (g) in FIG. 60 show a case where attention is paid to the pixel 3, which is another pixel. Video data obtained by dividing the video data D3 written and displayed in the pixel 3 is denoted as D31, D32, and D33. The emission brightness corresponding to each data is L31, L32, and L33.

  The pixel 3 exists in the center of the screen. The operation timing in this pixel is basically the same as that of pixel 1, and the phase is shifted by two lines. Therefore, the scan signal of each pixel does not become High at the same time.

  As described above, the video display device according to the present embodiment is processed so that data to be applied to the data electrodes is rearranged in advance and three data are arranged per one horizontal cycle. A scan signal for selecting in the vertical direction outputs a high signal three times per vertical synchronization signal. Furthermore, a plurality of scan signals do not become High at the same time.

  By writing data at such a timing, the light emission waveform as shown in part (e) of FIG. 60 is obtained from the video display apparatus of the present embodiment. This waveform is composed of a first light emitting component and a second light emitting component as shown in FIG. Or it consists of an intermittent light emission component and a continuous light emission component. When the pixel emits light with this waveform, an ideal improvement in the amount of tailing and the amount of flicker is performed.

  In this embodiment, an external memory is provided to control the light emission waveform by rearranging data, so that the pixel structure of the display panel is updated once per vertical synchronization signal, for example, by adding scan electrodes. Therefore, it is not necessary to change from a general configuration such as this, and an existing display panel can be used.

  Further, the duty ratio D of the intermittent light emission component can be controlled by managing the rearrangement of data signals. Similarly, the light emission phase of the intermittent light emission component can be controlled by managing the rearrangement of data signals.

[Supplement]
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Needless to say, these are also included in the technical scope of the present invention.

  According to another aspect of the present invention, there is provided a video display device comprising: a video display unit that modulates light based on a video signal; and a light source body that illuminates the video display unit. The image display means may be illuminated with illumination light obtained by mixing intermittent light indicating a waveform of emission intensity in the form of a rectangular pulse synchronized with a continuous light having a constant emission intensity. .

  According to the said structure, the light source body of this invention makes the light which mixed the intermittent light and the continuous light the illumination light. Therefore, the illumination light obtained by the light source body of the present invention has a constant light emission intensity by the continuous light, and the light emission intensity increases intermittently during the time when the intermittent light is emitted.

  Therefore, when the moving object is displayed by the image display means of the present invention, the contour of the object is illuminated with a light emission intensity corresponding to two kinds of light emission intensity of continuous light and intermittent light. As a result, the contour of the moving object is displayed by two types of luminance changes including a portion where the luminance changes corresponding to only the continuous light and a portion where the luminance changes corresponding to the intermittent light and the continuous light. It will be.

  As a result, in the image displaying the outline of the moving object, the observer cannot distinguish the contrast of the portion where the luminance changes corresponding to only the continuous light, and the luminance corresponding to the intermittent light and continuous light. Only the contrast of the portion where the value changes is identified. Thereby, it is possible to improve moving image tailing that occurs when a moving object is displayed.

  Further, the present inventors have confirmed that the amount of flicker can be reduced by adjusting the duty ratio of intermittent light in the illumination light obtained by the light source body of the present invention. For example, it has been confirmed that if the duty ratio of intermittent light is set to 20% and the brightness of the continuous light with respect to the brightness of the illumination light is set to 20%, the flicker amount that has been conventionally 90% can be reduced to 75%.

  As described above, the video display apparatus of the present invention uses illumination light as a mixture of intermittent light and continuous light, so that it is possible to simultaneously improve moving image tailing and flicker interference.

  Furthermore, it is preferable that the emission intensity of the intermittent light and the continuous light is set to a level that can be perceived by human eyes.

  According to the above configuration, since both the intermittent light and the continuous light are set to a level that can be perceived by the human eye (for example, 90 nit), the object displayed on the video display means by these lights is also the eyes of the observer. It will be easily visible. Therefore, the visibility of the object displayed by the video display means can be improved.

  Furthermore, in the video display device of the present invention, the light source body is disposed apart from the video display means, and the intermittent light and the continuous light are formed between the light source body and the video display means. The structure mixed in the space to be performed may be sufficient.

  That is, a non-light-emitting LCD, which is an example of a video display device, includes a so-called direct-type backlight as a light source on the back surface of a liquid crystal panel as video display means. Therefore, in a non-light emitting LCD, a space is formed between the image display means and the light source body.

  In the above configuration, the intermittent light and the continuous light are mixed using the space formed in this way, so that it is possible to reduce moving image tailing and flicker interference in a video display device using a direct type backlight as a light source. It becomes possible.

  Moreover, the structure provided with the light mixing means which mixes the said intermittent light and the said continuous light may be sufficient as the video display apparatus of this invention.

  According to the above configuration, since the video display device of the present invention includes the light mixing means, it is possible to reliably mix intermittent light and continuous light. Therefore, it is possible to more reliably obtain the moving image tailing improvement effect and flicker interference improvement effect obtained by mixing intermittent light and continuous light.

  Furthermore, in the video display device having the above-described configuration, the light mixing unit is a light guide plate, the light source body is disposed along the same end surface of the light guide plate, and the light guide plate includes the intermittent light and the intermittent light. The configuration may be such that the light mixed with the continuous light is guided from the end face on the side where the light source body is disposed to the end face on the side facing the video display means and output to the video display means.

  That is, in an LCD as an example of a video display device, a so-called side-edge type is provided, in which a light guide plate is provided on the back of a liquid crystal panel as video display means, and the liquid crystal panel is illuminated by guiding illumination light from a light source through the light guide plate. Some use a light source.

  In the present invention, since such a light guide plate is used to mix the continuous light emitted by the light source body and the intermittent light to illuminate the video display means, in the video display device using the side edge type light source, Pulling and flicker interference can be reduced.

  Furthermore, in the video display device having the above-described configuration, the light source body includes a first light source body that emits the intermittent light and a second light source body that emits the continuous light, and controls turning on / off of the first light source body. The 1st light source body drive means to perform and the structure provided with the 2nd light source body drive means which controls lighting / light extinction of the said 2nd light source body may be sufficient.

  According to the above configuration, each of the intermittent light and the continuous light is emitted by the corresponding light source among the first light source body and the second light source body. Further, the first light source body and the second light source body are controlled independently by the first light source body driving means and the second light source body driving means, respectively.

  Therefore, in order to optimize the light emission state of the intermittent light, the circuit configuration of the first light source body and the first light source body driving means may be optimized, and in order to optimize the light emission state of the continuous light, The circuit configurations of the two light source bodies and the second light source body driving means may be optimized. As described above, since the light emission states of intermittent light and continuous light can be optimized independently, cost reduction can be realized by simplifying the circuit configuration, and the reliability of the circuit can be improved. It becomes easy.

  Furthermore, it is preferable that the first light source body driving means switches at least one of power, current, and voltage supplied to the first light source body in synchronization with the video signal.

  That is, the intermittent light is light indicating a waveform of light emission intensity in a rectangular pulse shape synchronized with the video signal. Therefore, intermittent light can be easily generated by switching the power supplied to the light source body so as to be turned on / off in synchronization with the video signal.

  In the present invention, the power supplied from the first light source body driving means to the first light source body is configured to be switched in synchronization with the video signal, so that intermittent light can be easily generated. Therefore, the moving image tailing improvement effect and flicker interference reduction effect according to the present invention can be obtained with a simpler circuit configuration.

  Furthermore, it is preferable that the second light source body driving means supplies at least one of electric power, current, and voltage to the second light source body at a constant value.

  That is, the continuous light is light that always shows a constant light emission intensity. Therefore, continuous light can be easily generated by supplying a constant power or the like to the light source body.

  In the present invention, since the second light source body driving means is configured to supply constant power or the like to the second light source body, it is possible to easily generate continuous light. Therefore, the moving image tailing improvement effect and flicker interference reduction effect according to the present invention can be obtained with a simpler circuit configuration.

  Further, the second light source body driving means controls at least one of power, current, and voltage supplied to the second light source body at a frequency that is three times or more the frequency of the video signal. May be.

  That is, the human eye is very insensitive to light that repeatedly flickers at a frequency of about 150 Hz, and hardly reacts to light that blinks repeatedly at a frequency exceeding about 300 Hz. Therefore, strictly speaking, even light that blinks repeatedly may be observed as continuous light by the human eye.

  Therefore, when the frequency of the video signal is set to 60 Hz, for example, if the power supplied to the second light source body is controlled at a frequency that is three times or more of 60 Hz, the second light source body can easily achieve substantial sustained light. Can be issued. Thereby, the effect of improving the moving image tailing and the effect of reducing flicker interference according to the present invention can be obtained with a simpler circuit configuration.

  As the first light source body and the second light source body, semiconductor light emitting elements such as light emitting diodes can be used.

  The second light source body may emit continuous light based on a light emission principle different from that of the first light source body.

  According to the above configuration, since the second light source body that emits continuous light based on a light emission principle different from that of the first light source body is used, a light emitting element suitable for continuous light emission, for example, a cold cathode fluorescent lamp is used. be able to. Therefore, the lifetime of the second light source body can be increased and the durability can be improved.

  Further, the video display device of the present invention includes an intermittent optical signal generating means for generating an intermittent optical signal that repeats an on / off state in synchronization with the video signal, and a continuous optical signal generation for generating a continuous optical signal that is always on. And the light source body may emit the illumination light based on an illumination light signal obtained by combining the intermittent light signal and the continuous light signal.

  According to the above configuration, intermittent light can be generated by the light source body based on the intermittent light signal, and continuous light can be generated by the light source body based on the continuous light signal. Therefore, based on the illumination light signal obtained by combining the intermittent light signal and the continuous light signal, illumination light in which the intermittent light and the continuous light are mixed can be obtained from one light source body. Therefore, it is possible to simplify the setting of the optical system and reduce luminance unevenness and color unevenness that may occur in the image display means.

  Furthermore, the frequency of the continuous optical signal may be three times or more the frequency of the video signal.

  According to the above configuration, when the frequency of the video signal is set to 60 Hz, for example, light that is substantially recognized as continuous light by the human eye can be easily emitted from the light source body. Thereby, the effect of improving the moving image tailing and the effect of reducing flicker interference according to the present invention can be obtained with a simpler circuit configuration.

  As the light source body, a semiconductor light emitting element such as a light emitting diode can be used.

  Furthermore, in the video display device of the present invention, the light source body always controls the third light source body that emits light at a constant intensity, and the intensity of light emitted from the third light source body in synchronization with the video signal. It may be configured to include shutter means.

  That is, as described above, the emission intensity of the illumination light obtained by mixing intermittent light and continuous light is set so that the emission intensity is intermittently increased while maintaining a constant emission intensity by the continuous light. The Therefore, if the light intensity emitted from the third light source is controlled by the shutter means so that the light emission intensity is intermittently increased while maintaining a constant light emission intensity, the intermittent light and the continuous light are mixed. An illumination intensity similar to that of the illumination light can be obtained from the light generated by the third light source body.

  Thus, since the illumination light in which the intermittent light and the continuous light are mixed can be obtained from only the third light source body, the above-mentioned moving image tailing and flicker interference improvement effects can be obtained at the same time. In addition, since the third light source body only needs to emit light at a constant intensity, the burden on the third light source body can be reduced.

  Further, the shutter means may be a device that transmits or semi-transmits the light emitted from the third light source body in synchronization with the video signal, or the light emitted from the third light source body. It may be permeate or block. Note that “semi-transmitting light” means transmitting light emitted by the third light source body at a certain ratio other than 0%. Further, “blocking light” means that the transmittance is 0%.

  Furthermore, as the third light source body, a semiconductor light emitting element, for example, a light emitting diode can be used. Further, a cold cathode fluorescent lamp may be used as the third light source body.

  Furthermore, the moving image tailing and flicker interference improving effect obtained by the video display device of the present invention can be suitably obtained even when the video display means is a liquid crystal panel, that is, when the video display device of the present invention is applied to an LCD. be able to. Therefore, in LCDs whose devices are becoming larger in recent years, it is possible to effectively reduce moving image tailing and flicker interference.

  The video display device of the present invention can also be applied to a case where an active matrix driven self-luminous element is used as a display panel, and for example, an organic EL can be used. An organic EL has a light emitting element for each pixel and a capacitor for storing image information for each light emitting element. By accessing this capacitor a plurality of times within a vertical period, the light emission of the pixel can be reduced. It can be formed from a light emitting component and a second light emitting component. Alternatively, by dividing the capacitor, light emission of the pixel can be formed from the first light emission component and the second light emission component.

  Further, the display panel is supplied with video data rearranged in advance with respect to the time axis, and by selecting the same pixel three times with respect to the vertical period of the video, the first light emission component and the second light emission component It is possible to emit light from a pixel formed from the above.

  Since the video display device of the present invention illuminates the video display means with illumination light in which continuous light and intermittent light are mixed, it is possible to achieve both improvement of moving image tailing and reduction of flicker interference. Flicker not only makes the user uncomfortable, but also causes a reduction in attention and work efficiency, and adversely affects health such as eye fatigue, but the present invention can prevent such adverse effects. Furthermore, reducing flicker is indispensable for improving display quality in a video display device with high brightness and a large screen. Thus, according to the present invention, it is possible to provide an optimal display quality for the observer.

  The video display device of the present invention includes video display means for modulating light in accordance with a video signal, and a light source body for illuminating the video display means. The light source body includes flickerless continuous light and The video display means may be illuminated with illumination light composed of intermittent light synchronized with the video signal.

  Furthermore, in the invention having the above-described configuration, the first light source body driving unit and the second light source body driving unit may be further provided. In addition, a light source body shall consist of a 1st light source group and a 2nd light source group, in order to output a continuous light by controlling a 1st light source group with a 1st light source body drive means in order to output intermittent light. The second light source group is controlled by the second light source body driving means.

  Further, the first light source drive means may be configured to control the first light source group by switching the voltage or current in synchronization with the video signal. The second light source drive means may control the second light source group by supplying voltage or current stably or changing it asynchronously with the video signal. Furthermore, the light source body may be configured by a first light source body and a second light source body having different light emission principles.

  Furthermore, the video display device of the present invention has a plurality of control signal generating means for generating an electric signal for causing the light source to emit light, and combines the electric signals output from the plurality of control signal generating means to supply the light source to the light source. It is good also as a structure provided with the control means.

  In the above configuration, in order to obtain the intermittent light emission component, one of the plurality of control signal generating means may generate an ON / OFF repeated signal synchronized with the video signal. In order to obtain a continuous light emission component, if one of the plurality of control signal generation means generates a signal that is always on with a constant amplitude or that varies asynchronously with the video signal. Good.

  Furthermore, the video display device of the present invention may further include a shutter unit that controls illumination light from the light source body. The shutter means controls the light intensity of the illumination light from the light source in synchronization with the video signal.

  The shutter means may be configured to act on all or most of the illumination light. In this case, the light intensity control by the shutter means may repeat the transmission control that allows light to pass 100% and the semi-transmission control that allows light to pass at a predetermined ratio other than 0%.

  The shutter unit may be configured to act on a part of the illumination light. In this case, the light intensity control of the shutter means repeats transmission control that allows light to pass 100% and blocking control that blocks light 100%.

In addition, the video display device of the present invention occupies a time of D% of the vertical period of the video signal in the video display device that displays the video by modulating the luminance of the pixel based on the video signal, and within the vertical period. The first light-emitting component having a light emission intensity of S% of the light emission intensity of the pixel displayed in (1) and the light emission of the pixel displayed within the vertical period and occupying a time of (100-D)% of the vertical period. Emitting a second luminescent component having an emission intensity of (100-S)% of the intensity;
The values of D and S are
Condition A: 62 ≦ S <100 and 0 <D <100 and D <S, or Condition B: 48 <S <62 and D ≦ (S−48) /0.23
It is characterized by satisfying.

  In the above configuration, the duty ratio of the first light emission component and the second light emission component is indicated by D, and the light emission intensity ratio is indicated by S. The present inventors have examined the amount of tailing and flicker obtained by changing the duty ratio D and the light emission intensity ratio S, and as a result, the duty ratio D and the light emission intensity ratio S should satisfy the condition A or the condition B. It was found that the tailing amount and the flicker amount are simultaneously improved by setting to. Therefore, according to the video display device having the above configuration, the amount of tailing and the amount of flicker can be improved at the same time.

  Further, the video display device having the above-described configuration includes video display means for setting the transmittance of the pixel based on the video signal, and a light source body that illuminates the video display means, and the first light emitting component and the first light emitting element The light emission intensity of each of the two light emitting components is preferably controlled by the light source body.

  Further, the light source body is preferably a semiconductor light emitting element, such as a light emitting diode. The light source body may be a cold cathode fluorescent lamp.

  Alternatively, the video display device having the above configuration includes video display means for setting the transmittance of the pixel based on the video signal, and the control of the emission intensity in each of the first light emission component and the second light emission component is as follows. Preferably, this is performed by the video display means.

  The video display means may be an organic EL panel or a liquid crystal panel.

  The display panel is an active matrix driven self-luminous element. For example, organic EL. Each pixel has a light emitting element. Each of the light emitting elements has a capacitor for storing image information, but the light emission of the pixel may be used as the first light emitting component and the second light emitting component by accessing the capacitor a plurality of times within the vertical period. Alternatively, the light emission of the pixel may be used as the first light emission component and the second light emission component by dividing the capacitor.

  Further, the display panel is supplied with video data rearranged in advance with respect to the time axis, and by selecting the same pixel three times for the vertical period of the video, the first light emission component and the second light emission component are selected. It is good also as light emission of a pixel.

  The video display device having the above-described configuration includes a video display unit that sets a pixel transmittance based on the video signal, and a light source body that illuminates the video display unit, and includes the video display unit and the light source unit. A light control unit disposed between the optical paths formed between the light source units to control the intensity of illumination light of the light source body to control the light emission intensity of each of the first light emission component and the second light emission component; You may have.

  According to the above configuration, by controlling the intensity of the illumination light of the light source body using the light control means, it is possible to easily perform luminance control for the first light emission component and the second light emission component. In addition, since it is sufficient that the light source body emits light with a constant intensity, it is possible to reduce the burden on the light source body.

  Further, the light control means may be a device that totally transmits or semi-transmits illumination light of the light source body, or may be a device that completely transmits or blocks the illumination light. Note that “semi-transmitting light” means transmitting light emitted from the light source body at a certain ratio other than 0%. Further, “blocking light” means that the transmittance is 0%.

  Furthermore, a semiconductor light emitting element, for example, a light emitting diode can be used as the light source body. Further, a cold cathode fluorescent lamp may be used as the light source body.

  According to another aspect of the present invention, there is provided a video display device comprising: a video display unit configured to set a transmittance based on the video signal; and a light source body that illuminates the video display unit. The image display means is illuminated with illumination light obtained by mixing intermittent light indicating a pulsed emission intensity waveform synchronized with the video signal and continuous light having a constant emission intensity, and the first display The light emission intensity of the pixel in each of the light emission component and the second light emission component may be provided by the intermittent light and the continuous light.

  According to the above configuration, the image display means is illuminated by intermittent light and continuous light. With the light obtained by mixing the intermittent light and the continuous light, light substantially equivalent to the light obtained by mixing the first light emitting component and the second light emitting component can be obtained.

  Therefore, even with the video display device having the above-described configuration, it is possible to obtain the effect of simultaneously improving the trailing amount and the flicker amount.

  Moreover, it is preferable that the light emission intensity | strength of the said intermittent light and the said continuous light is set to the level which can be perceived by human eyes.

  According to the above configuration, since the luminance of the pixels displayed within the vertical period is set to a level that can be perceived by the human eye (for example, 90 nits), the object displayed on the video display device of the present invention is also observed. It will be easily visible to the eyes of the person. Therefore, the visibility of the object displayed by the video display device of the present invention can be improved.

  Furthermore, the video display device of the present invention includes scene change detection means for detecting the scene change amount of the video based on the video signal, and changes the value of S or D according to the scene change amount. Is preferred.

  According to the above configuration, since the duty ratio S or the light emission intensity ratio D is changed according to the motion of the video represented by the scene change amount, the trailing amount and the flicker amount can be adjusted according to the motion of the video. . Therefore, the flicker amount and the tailing amount can be improved according to whether the video displayed on the video display device is a still image or a moving image.

  Further, a scene change detecting means for detecting the average luminance level of the video based on the video signal may be provided, and the value of S or D may be changed according to the average luminance level of the video. This is because the flicker amount of the video changes according to the level of the average luminance level of the video. That is, the flicker amount tends to increase as the average luminance level increases. In the above configuration, since the duty ratio S or the light emission intensity ratio D is changed according to the average luminance level, the optimum S and D values are selected according to the average luminance level, and the flicker amount and the tailing amount are improved simultaneously. be able to.

  According to another aspect of the present invention, there is provided a video display device comprising: a video display unit configured to set a pixel transmittance based on the video signal; and a light source body that illuminates the video display unit. The body is disposed apart from the video display means, and the first light emission component and the second light emission component are mixed in a space formed between the light source body and the video display means. It is preferable.

  That is, a non-light-emitting LCD, which is an example of a video display device, includes a so-called direct-type backlight as a light source on the back surface of a liquid crystal panel as video display means. Therefore, in a non-light emitting LCD, a space is formed between the image display means and the light source body.

  In the above configuration, since the first light emitting component and the second light emitting component are mixed using the space formed in this manner, in the video display device using the direct type backlight as the light source, the moving image tailing and flicker are performed. Interference can be reduced.

  Furthermore, the video display device of the present invention, in the video display device having the above-described configuration, emits video display means for setting pixel transmittance based on the video signal, the first light emission component, and the second light emission component. It is preferable to include a light source body that illuminates the video display means and a light mixing means that mixes the first light emission component and the second light emission component.

  According to the above configuration, since the video display device of the present invention includes the light mixing unit, the first light emitting component and the second light emitting component can be mixed reliably. Therefore, it is possible to more reliably obtain the moving image tailing improvement effect and flicker interference improvement effect obtained by the first light emission component and the second light emission component.

  Furthermore, in the video display device having the above-described configuration, the light mixing unit is a light guide plate, the light source body is disposed along the same end surface of the light guide plate, and the light guide plate includes the first light guide plate. Light mixed with the light emitting component and the second light emitting component is guided from the end surface on the side where the light source body is disposed to the end surface on the side facing the image display means, and is output to the image display means. It is preferable.

  That is, in an LCD as an example of a video display device, a so-called side-edge type is provided, in which a light guide plate is provided on the back of a liquid crystal panel as video display means, and the liquid crystal panel is illuminated by guiding illumination light from a light source through the light guide plate. Some use a light source.

  In the present invention, since such a light guide plate is used to illuminate the image display means by mixing the first light emission component and the second light emission component emitted from the light source body, an image using a side edge type light source is used. In the display device, it is possible to reduce moving image tailing and flicker interference.

  Furthermore, the video display device of the present invention further includes a video display unit configured to set a pixel transmittance based on the video signal, and a light source body that illuminates the video display unit in the video display device having the above-described configuration. The light source body includes a first light source body that emits the intermittent light, and a second light source body that emits the continuous light, and controls the turning on / off of the first light source body; It is preferable to include second light source body driving means for controlling lighting / extinction of the second light source body.

  According to the said structure, each of a 1st light emission component and a 2nd light emission component is emitted by the corresponding light source among a 1st light source body and a 2nd light source body. Further, the first light source body and the second light source body are controlled independently by the first light source body driving means and the second light source body driving means, respectively.

  Therefore, in order to optimize the light emission state of the first light emission component, the circuit configurations of the first light source body and the first light source body driving means may be optimized, and the light emission state of the second light emission component is optimized. In order to do so, the circuit configurations of the second light source body and the second light source body driving means may be optimized. As described above, since the respective light emission states of the first light emission component and the second light emission component can be optimized independently, cost reduction can be realized by simplifying the circuit configuration, and circuit reliability can be achieved. It becomes easy to improve the property.

  Furthermore, it is preferable that the first light source body driving means switches at least one of power, current, and voltage supplied to the first light source body in synchronization with the video signal.

  That is, the first light emission component can be realized by intermittent light indicating a rectangular pulse-shaped light emission intensity waveform synchronized with the video signal. Therefore, intermittent light can be easily generated by switching the power supplied to the light source body so as to be turned on / off in synchronization with the video signal.

  In the present invention, the power supplied from the first light source body driving means to the first light source body is configured to be switched in synchronization with the video signal, so that intermittent light can be easily generated. Therefore, the moving image tailing improvement effect and flicker interference reduction effect according to the present invention can be obtained with a simpler circuit configuration.

  The second light source body driving means preferably supplies at least one of electric power, current, and voltage to the second light source body at a constant value.

  That is, the second light emitting component can be realized by continuous light that always shows a constant light emission intensity. Therefore, continuous light can be easily generated by supplying a constant power or the like to the light source body.

  In the present invention, since the second light source body driving means is configured to supply constant power or the like to the second light source body, it is possible to easily generate continuous light. Therefore, the moving image tailing improvement effect and flicker interference reduction effect according to the present invention can be obtained with a simpler circuit configuration.

  In addition, the second light source body driving means is configured to supply at least one of power, current, and voltage supplied to the second light source body at a frequency (for example, 150 Hz) that is three times or more the vertical frequency of the video signal. It is preferable to control.

  That is, the human eye is very insensitive to light that repeatedly flickers at a frequency of about 150 Hz, and hardly reacts to light that blinks repeatedly at a frequency exceeding about 300 Hz. Therefore, strictly speaking, even the light blinking repeatedly may be observed as the second light emitting component in the human eye.

  Therefore, in the case where the frequency of the video signal is set to 60 Hz, for example, if the power supplied to the second light source body is controlled at a frequency three times or more of 60 Hz, the second light source body can easily make a substantial second. The light emitting component can be emitted. Thereby, the effect of improving the moving image tailing and the effect of reducing flicker interference according to the present invention can be obtained with a simpler circuit configuration.

  As the first light source body and the second light source body, semiconductor light emitting elements such as light emitting diodes can be used.

  In addition, it is preferable that the second light source body emits the second light emitting component by a light emission principle different from that of the first light source body.

  According to the above configuration, since the second light source body that emits continuous light according to a light emission principle different from that of the first light source body is used, a light emitting element suitable for light emission of the second light emitting component, for example, cold cathode fluorescent lamp A lamp can be used. Therefore, the lifetime of the second light source body can be increased and the durability can be improved.

  Furthermore, the video display device of the present invention is the video display device having the above-described configuration, the intermittent optical signal generating means for generating the intermittent optical signal that repeats the on / off state in synchronization with the video signal, and the continuous light that is always in the on state. A continuous light signal generating means for generating a signal, and the first light emission component and the second light emission component are emitted based on the illumination light signal obtained by combining the intermittent light signal and the continuous light signal. preferable.

  According to the above configuration, the first light emission component can be generated by the light source body based on the intermittent light signal, and the second light emission component can be generated by the light source body based on the continuous light signal. Therefore, based on the illumination light signal obtained by combining the intermittent light signal and the continuous light signal, it is possible to obtain illumination light in which the first light emission component and the second light emission component are mixed from one light source body. Therefore, it is possible to simplify the setting of the optical system and reduce luminance unevenness and color unevenness that may occur in the image display means.

  Moreover, it is preferable that the frequency of the continuous optical signal is a frequency (for example, 150 Hz) that is three times or more the vertical frequency of the video signal.

  According to the above configuration, when the frequency of the video signal is set to 60 Hz, for example, light that is substantially recognized as the second light emission component by the human eye can be easily emitted from the light source body. Thereby, the effect of improving the moving image tailing and the effect of reducing flicker interference according to the present invention can be obtained with a simpler circuit configuration.

  The first light emitting component and the second light emitting component are emitted by a semiconductor light emitting element, for example, a light emitting diode.

  The second light emission component may be formed by a set of pulse components having a frequency higher than the vertical frequency of the video signal. The frequency of the pulse component is preferably at least three times the vertical frequency of the video signal, for example, 150 Hz or more.

  According to another aspect of the present invention, there is provided a video display device that displays video by modulating pixel luminance based on a video signal, video display means for setting a pixel transmittance based on the video signal, and the video A first light source that emits intermittent light showing a waveform of a pulsed emission intensity synchronized with a signal, and a second light source that emits continuous light showing a constant emission intensity, the intermittent light and the continuous light, The image display means may be illuminated with illumination light obtained by mixing the above.

  According to the said structure, the light which mixed the intermittent light which a 1st light source body emits and the continuous light which a 2nd light source body emits is made into illumination light. Therefore, the illumination light obtained by the light source body of the present invention has a constant light emission intensity by the continuous light, and the light emission intensity increases intermittently during the time when the intermittent light is emitted.

  Therefore, when the moving object is displayed by the image display means of the present invention, the contour of the object is illuminated with a light emission intensity corresponding to two kinds of light emission intensity of continuous light and intermittent light. As a result, the contour of the moving object is displayed by two types of luminance changes including a portion where the luminance changes corresponding to only the continuous light and a portion where the luminance changes corresponding to the intermittent light and the continuous light. It will be.

  As a result, in the image displaying the outline of the moving object, the observer cannot distinguish the contrast of the portion where the luminance changes corresponding to only the continuous light, and the luminance corresponding to the intermittent light and continuous light. Only the contrast of the portion where the value changes is identified. Thereby, it is possible to improve moving image tailing that occurs when a moving object is displayed.

  Further, the present inventors have confirmed that the amount of flicker can be reduced by adjusting the duty ratio of intermittent light in the illumination light obtained by the light source body of the present invention. For example, it has been confirmed that if the duty ratio of intermittent light is set to 20% and the brightness of the continuous light with respect to the brightness of the illumination light is set to 20%, the flicker amount that has been conventionally 90% can be reduced to 75%.

  As described above, the video display apparatus of the present invention uses illumination light as a mixture of intermittent light and continuous light, so that it is possible to simultaneously improve moving image tailing and flicker interference.

  In particular, each of intermittent light and continuous light is emitted by a corresponding light source of the first light source body and the second light source body.

  Therefore, the first light source body may be optimized to optimize the light emission state of intermittent light, and the second light source body may be optimized to optimize the light emission state of continuous light. As described above, since the light emission states of intermittent light and continuous light can be optimized independently, cost reduction can be realized by simplifying the circuit configuration, and the reliability of the circuit can be improved. It becomes easy.

  Furthermore, the video display device having the above configuration includes a first light source body driving unit that controls lighting / extinction of the first light source body, and a second light source body driving unit that controls lighting / extinction of the second light source body. It is preferable to provide.

  According to the above configuration, in order to optimize the light emission state of the intermittent light, the circuit configuration of the first light source body driving unit may be optimized, and in order to optimize the light emission state of the continuous light, the second light source body driving unit may be optimized. What is necessary is just to optimize the circuit structure of a light source body drive means. As described above, since the light emission states of intermittent light and continuous light can be optimized independently, cost reduction can be realized by simplifying the circuit configuration, and the reliability of the circuit can be improved. It becomes easy.

  Furthermore, it is preferable that the first light source body driving means switches at least one of power, current, and voltage supplied to the first light source body in synchronization with the video signal.

  That is, intermittent light is light that shows a pulse-like waveform of emission intensity synchronized with a video signal. Therefore, intermittent light can be easily generated by switching the power supplied to the light source body so as to be turned on / off in synchronization with the video signal.

  In the present invention, the power supplied from the first light source body driving means to the first light source body is configured to be switched in synchronization with the video signal, so that intermittent light can be easily generated. Therefore, the moving image tailing improvement effect and flicker interference reduction effect according to the present invention can be obtained with a simpler circuit configuration.

  Furthermore, it is preferable that the second light source body driving means supplies at least one of electric power, current, and voltage to the second light source body at a constant value.

  That is, the continuous light is light that exhibits a constant light emission intensity. Therefore, continuous light can be easily generated by supplying a constant power or the like to the light source body.

  In the above configuration, since the second light source body driving unit is configured to supply constant power or the like to the second light source body, continuous light can be easily generated. Therefore, the moving image tailing improvement effect and flicker interference reduction effect according to the present invention can be obtained with a simpler circuit configuration.

  Further, the second light source body driving means supplies at least one of power, current, and voltage supplied to the second light source body at a frequency (for example, 150 Hz) that is at least three times the vertical frequency of the video signal. It may be controlled.

  That is, the human eye is very insensitive to light that repeatedly flickers at a frequency of about 150 Hz, and hardly reacts to light that blinks repeatedly at a frequency exceeding about 300 Hz. Therefore, strictly speaking, even light that blinks repeatedly may be observed as continuous light by the human eye.

  Therefore, when the frequency of the video signal is set to 60 Hz, for example, if the power supplied to the second light source body is controlled at a frequency that is three times or more of 60 Hz, the second light source body can easily achieve substantial sustained light. Can be issued. Thereby, the effect of improving the moving image tailing and the effect of reducing flicker interference according to the present invention can be obtained with a simpler circuit configuration.

  For the first light source body and the second light source body, semiconductor light emitting elements such as light emitting diodes can be used.

  The second light source body may emit the continuous light based on a light emission principle different from that of the first light source body.

  According to the above configuration, since the second light source body that emits continuous light based on a light emission principle different from that of the first light source body is used, a light emitting element suitable for continuous light emission, for example, a cold cathode fluorescent lamp is used. be able to. Therefore, the lifetime of the second light source body can be increased and the durability can be improved.

  In addition, the video display device of the present invention occupies a time of D% of the vertical period of the video signal in the video display device that displays the video by modulating the luminance of the pixel based on the video signal, and within the vertical period. The first light-emitting component having a light emission intensity of S% of the light emission intensity of the pixel displayed in (1) and the light emission of the pixel displayed within the vertical period and occupying a time of (100-D)% of the vertical period. A scene change detecting means for emitting a second light emission component having a light emission intensity of (100-S)% of the intensity and detecting a scene change amount of the video based on the video signal, and according to the scene change amount. In this case, the S or D value may be changed.

  Furthermore, it is preferable that the scene change detection means delays the video signal using a memory for a frame period and calculates a scene change amount based on a difference amount from the delayed signal. The scene change detection means may be configured to calculate an average luminance level of the video and calculate a scene change amount based on a difference amount between frames of the average luminance level.

  The scene change amount calculated in this way is the amount of motion of the video signal in units of screens. By controlling the light emission intensity ratio S and the duty ratio D according to the scene change amount, the optimum tailing amount and flicker amount can be improved.

  The video display device according to the present invention occupies a time of D% of the vertical period of the video signal in the video display device that displays the video by modulating the luminance of the pixel based on the video signal. The first light-emitting component having a light emission intensity of S% of the light emission intensity of the pixel displayed in (1) and the light emission of the pixel displayed within the vertical period and occupying a time of (100-D)% of the vertical period. A second luminance component having an emission intensity of (100-S)% of the intensity, and an average luminance detecting means for detecting an average luminance level of the video based on the video signal, and according to the average luminance level In this case, the S or D value may be changed.

  In addition, the video display device of the present invention occupies a time of D% of the vertical period of the video signal in the video display device that displays the video by modulating the luminance of the pixel based on the video signal, and within the vertical period. The first light-emitting component having a light emission intensity of S% of the light emission intensity of the pixel displayed in (1) and the light emission of the pixel displayed within the vertical period and occupying a time of (100-D)% of the vertical period. And a second light emitting component having a light emission intensity of (100−S)% of the intensity, and includes a histogram detection means for detecting a histogram of the video based on the video signal, and depending on the histogram, the S or The structure which changes the value of D may be sufficient.

  In other words, by obtaining information that the screen is bright and dark from the absolute value of the average luminance level and the luminance distribution (histogram) as well as the amount of motion of the video to be displayed (average luminance level difference between frames) It is possible to improve the tailing amount and flicker amount.

  According to the present invention, it is possible to simultaneously improve moving image tailing and flicker. These effects are particularly prominent when the video display device is increased in brightness and size. Therefore, the present invention is particularly suitable for increasing the size and brightness of the LCD.

It is a block diagram which shows the structure of the video display apparatus which concerns on one Embodiment of this invention. 2 is a waveform showing a temporal response of light emission of a pixel when attention is paid to an arbitrary pixel in the video display device of FIG. 1. FIG. 3A and FIG. 3B are diagrams showing an example of the light emission waveform of the pixel in the video display device of FIG. It is a figure for demonstrating the effect of the video display apparatus of FIG. 1 qualitatively. FIG. 5A to FIG. 5I are diagrams for quantitatively explaining the effect of the video display device of FIG. It is a figure which shows collectively the characteristic of each light emission pattern in FIG. It is a figure which shows collectively the characteristic of each light emission pattern in FIG. 8A to 8C show the relationship between the duty ratio D, the trailing amount, and the flicker amount when the emission intensity ratio S is fixed at 70% or 90% in the video display device of FIG. FIG. 9A to 9C show the light emission intensity ratio S and the tailing amount of the first light emission component when the duty ratio D is fixed at 10% or 70% in the video display device of FIG. It is a figure which shows the relationship between flicker amount. 10 (a) to 10 (b) are diagrams showing the relationship among the duty ratio D, the trailing amount, and the flicker amount when the emission intensity ratio S is fixed at 40% in the video display device of FIG. is there. 11 (a) and 11 (b) are diagrams showing the relationship among the duty ratio D, the amount of tailing, and the amount of flicker when the light emission intensity ratio S is fixed at 60% in the video display device of FIG. is there. It is a figure which shows the conditions of duty ratio D and light emission intensity ratio S which can acquire the simultaneous reduction effect of a trailing amount and flicker. FIGS. 13A and 13B are diagrams showing the relationship between the amount of tailing and the amount of flicker when the light emission intensity ratio S is 62% in the video display apparatus of FIG. FIGS. 14A and 14B are diagrams showing the relationship between the amount of tailing and the amount of flicker when the light emission intensity ratio S is 48% in the video display apparatus of FIG. FIGS. 15A and 15B show the upper limit of the duty ratio D with which the effect of simultaneously reducing the trailing amount and the flicker amount can be obtained in the range of 48 <S% <62 in the video display device of FIG. FIG. FIGS. 16A to 16C show the degree of improvement in tailing and flicker when six representative points are extracted for the emission intensity ratio S and the duty ratio D that satisfy the condition A or the condition B in FIG. It is a figure for demonstrating. FIGS. 17A and 17B are diagrams showing examples of light emission waveforms applicable to the video display device of FIG. 18 (a) and 18 (b) are diagrams showing other examples of light emission waveforms applicable to the video display device of FIG. FIG. 19 is a diagram showing another example of a light emission waveform applicable to the video display device of FIG. FIG. 20 is a diagram showing another example of a light emission waveform applicable to the video display device of FIG. When the luminance level range of the tailing to which the human eye responds is assumed to be 10% to 90% (see FIG. 5), the duty ratio D that can obtain the simultaneous improvement effect of the flickering of the tailing amount The emission intensity ratio S is shown. 22 (a) to 22 (c) show the emission intensity ratio S = when it is assumed that the tail luminance level range to which the human eye responds is 10% to 90% (see FIG. 5). It is a figure which shows the relationship between the amount of trailing and the amount of flicker in the case of 69% and S = 79%. 23 (a) and 23 (b) show a range of 69% <S% <79% when the luminance level range of the tail to which the human eye responds is assumed to be 10% to 90%. The upper limit of the duty ratio D at which the effect of simultaneously reducing the trailing amount and the flicker amount is obtained. It is a figure for demonstrating the flicker reduction effect by the video display apparatus of FIG. 1 by the result of subjective evaluation. It is sectional drawing of the video display apparatus which concerns on other embodiment of this invention. FIG. 26 is a diagram showing the relationship between the modulation waveform of the pixel and the light emission waveform of the light source when attention is paid to the pixel of the video display device of FIG. FIG. 26 is a diagram for qualitatively explaining the effect of the video display device of FIG. 25. FIG. 28A is a diagram showing a change in the transmittance of a pixel when a liquid crystal response is taken into account, and FIG. 28B is a diagram showing a change in luminance generated at the edge in the traveling direction with respect to the movement of the object. FIG. 28 (c) is a diagram showing a change in luminance that occurs at the rear edge with respect to the movement of the object. It is a figure which shows the phase of the 1st light emission component with respect to the response of a liquid crystal. 30 (a) to 30 (c) show the image display device of FIG. 25 when the duty ratio D = 30%, the emission intensity ratio S = 70%, and the liquid crystal time constant is 3.5 milliseconds. It is a figure for demonstrating an effect. It is a figure which shows the phase of the 1st light emission component in case duty ratio D = 30%, light emission intensity ratio S = 70%, and the time constant of a liquid crystal shall be 3.5 milliseconds. It is a figure which shows the structure of the pixel periphery of the organic panel provided in the video display apparatus concerning further another embodiment of this invention. It is a timing chart regarding operation | movement of organic EL which has a pixel shown in FIG. It is a figure which shows the structure of the video display apparatus which concerns on further another embodiment of this invention. It is a time chart for demonstrating operation | movement of the video display apparatus of FIG. It is a figure which shows the structure of the video display apparatus which concerns on further another embodiment of this invention. It is a figure which shows the structure of the video display apparatus which concerns on further another embodiment of this invention. It is a timing chart for demonstrating operation | movement of the video display apparatus of FIG. FIG. 39A and FIG. 39B are diagrams showing the relationship between continuous light and intermittent light, and the first light emission component and the second light emission component. It is a figure which shows the structure of the video display apparatus which concerns on further another embodiment of this invention. It is a timing chart for demonstrating operation | movement of the video display apparatus of FIG. FIG. 42A and FIG. 42B are diagrams showing a configuration example of the scene change detection circuit. It is a figure which shows typically the light emission intensity for 1 vertical period regarding the illumination light which illuminates the display panel of FIG. 44 (a) to 44 (c) are diagrams illustrating an example of a procedure for controlling illumination light that illuminates the display panel of FIG. 40 using a scene change detection signal. 45 (a) to 45 (d) are diagrams illustrating a procedure for controlling the light emission intensity ratio S2 using the scene change detection signal. 46 (a) and 46 (b) show the duty ratio D or emission intensity ratio by using the APL information obtained from the scene change detection circuit having the configuration shown in FIG. 42 (b) and the scene change amount in combination. It is a figure explaining the procedure which controls S2. It is a figure which shows the structure of the video display apparatus which concerns on further another embodiment of this invention. It is a figure which shows the structure of the video display apparatus which concerns on further another embodiment of this invention. 49 is a time chart showing the operation of the LCD of FIG. 48. It is a figure which shows the structure of the video display apparatus which concerns on further another embodiment of this invention. It is a figure which shows the structure of the video display apparatus which concerns on further another embodiment of this invention. 52 is a time chart showing the operation of the LCD of FIG. 51. It is a figure which shows the light emission waveform of the 2nd light emission component applicable to this invention. It is a figure for demonstrating the reduction effect of the amount of tailing at the time of using the light emission waveform shown to the (a) part of FIG. 54 shows the Fourier series calculation results of the light emission waveform shown in part (a) of FIG. 54 and the light emission waveform of the prior art. It is a block diagram which shows the structure of the video display apparatus which concerns on other embodiment of this invention. FIG. 57 is a timing chart showing an operation of the video display apparatus in FIG. 56. FIG. It is a block diagram which shows the structure of the video display apparatus which concerns on other embodiment of this invention. It is a timing chart which shows operation | movement of the video display apparatus which concerns on other embodiment of this invention. It is a timing chart which shows operation | movement of the video display apparatus which concerns on other embodiment of this invention. It is a figure for demonstrating the generation | occurrence | production principle of the tail resulting from hold type drive. It is a figure for demonstrating the principle of the tail improvement by impulse type light emission. It is a figure which shows the subject of the conventional animation tailing improvement technology quantitatively. 64 (a) and 64 (b) are diagrams quantitatively showing the problems of the conventional moving image tailing improvement technique. 64 (a) and 64 (b) are both shown in one drawing.

Explanation of symbols

1 video display device 2 display panel (video display means)
10 video display device 11 light source (light source body)
12 Display panel 30 Video display device 31 Display panel (video display means, shutter means)
36 lamp (light source, third light source)
37 Shutter (light control means, shutter means)
38 Light guide plate (light mixing means)
43 Shutter (light control means, shutter means)
50 video display device 51 display panel (video display means)
52 Intermittent light emitting device (light source)
53 Continuous light-emitting device (light source)
60 video display device 61 display panel (video display means)
67 Lamp drive circuit (first light source drive means)
68 Lamp drive circuit (second light source drive means)
69 lamp (first light source)
70 lamp (second light source)
77 Scene change detection circuit (scene change detection means)
100 video display device 101 light source (light source body)
102 Light source (light source body)
103 Display panel (video display means)
110 LCD (video display device)
111 Liquid crystal panel (video display means)
115 Power supply circuit (first light source drive means, second light source drive means)
116 Lamp (second light source)
117 lamp (first light source)
118 Light guide plate (light mixing means)
119 Timing generation circuit (first light source driving means)
120 switch (first light source driving means)
200 Video Display Device 201 Power Supply Circuit (First Light Source Drive Unit)
202 Power supply circuit (second light source driving means)
205 lamp (first light source)
206 Lamp (second light source)
400 LCD (video display device)
402 lamp (light source)
403 Timing generation circuit (intermittent optical signal generation means)
404 Reference voltage generating circuit (sustained light signal generating means)
407 Control signal (intermittent light signal)
408 Control signal (continuous light signal)
409 Control signal (illumination light signal)
601 EL pixel 602, 611 Scan electrode 603 Signal electrode 604, 606, 607, 608 TFT
605 Capacitor 609 EL element 610 Power supply 701 EL pixel 702, 703 Capacitor 704, 705, 706 TFT
707, 708 Scan electrode

Claims (12)

In a video display device that displays video by modulating the luminance of pixels based on a video signal,
Video display means for setting pixel transmittance based on the video signal;
A pulse having the same frequency as the vertical synchronizing signal of the video signal, occupying time of D% of the vertical period of the video signal, and having a light emission intensity of S1% of the light emission intensity of the pixels displayed in the vertical period A first light source that emits intermittent light showing a waveform of a light emission intensity,
A second light source body that occupies all the time of the vertical period and emits continuous light having a light emission intensity of (100-S1)% of the light emission intensity of the pixels displayed in the vertical period,
While illuminating the video display means with illumination light obtained by mixing the intermittent light and the continuous light,
An image display characterized by controlling light emission of the first light source body and the second light source body so as to reduce a tailing amount and a flicker amount from a tailing amount and a flicker amount in the case of S1 = 100. Equipment . First light source body driving means for controlling turning on / off of the first light source body;
The video display device according to claim 1, further comprising second light source body driving means for controlling lighting / extinction of the second light source body . 3. The first light source body driving means switches at least one of power, current, and voltage supplied to the first light source body in synchronization with the video signal. The video display device described in 1 . 4. The second light source body driving means supplies at least one of electric power, current, and voltage to the second light source body at a constant value. Video display device . The second light source body driving means controls at least one of power, current, and voltage supplied to the second light source body at a frequency that is at least three times the vertical frequency of the video signal. The video display device according to claim 2, wherein: The second light source body driving means controls at least one of power, current, and voltage supplied to the second light source body at a frequency of 150 Hz or more. 5. The video display device according to any one of 4 above . The video display device according to claim 1, wherein the first light source body and the second light source body are semiconductor light emitting elements . The video display device according to claim 7, wherein the semiconductor light emitting element is a light emitting diode . The video display device according to any one of claims 1 to 6, wherein the second light source body emits the continuous light according to a light emission principle different from that of the first light source body . The video display device according to claim 9, wherein at least one of the first light source body and the second light source body is a semiconductor light emitting element . The video display device according to claim 10, wherein the semiconductor light emitting element is a light emitting diode . The video display device according to claim 9, wherein the second light source body is a cold cathode fluorescent lamp .

Images