JP2002006815A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate animation blur of a liquid crystal display device. SOLUTION: The device is provided with a TFT type liquid crystal panel 10, a back light 20, a scan driver 13 which receives signals from a timing generating section 12 and forms scanning signals for the panel 10, a data driver 14 which supplies horizontal direction image data based on a clock and a back driver 18 which controls the back light 20 of the panel 10. The back light 20 is composed of plural fluorescent tubes L1, L2,...Ln which are successively turned on in accordance with the scanning timing of the panel 10. Back light beams are passed through the plural regions of the panel 10 with a prescribed timing to eliminate blur caused by a moving image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device capable of forming and projecting an image by modulating light from a light source with a light bubble, and more particularly to an illumination light source suitable for displaying a moving image. And a liquid crystal display device using the same.

[0002]

2. Description of the Related Art A liquid crystal display device for displaying an image by using a light source such as a lamp and a liquid crystal as a spatial light modulator as a light bubble can have a flat display portion and a cathode ray line in terms of power consumption. The number of pipes can be reduced as compared with the case where pipes are used, and in recent years, the use thereof has become very high. However, in the case of a liquid crystal display device, a light source for illumination is usually provided on the back of the liquid crystal panel, and if this backlight is not used, it is difficult to increase the brightness of a displayed image and the physical behavior of the liquid crystal As a result, there is a problem that the response speed to the image signal is low due to the structure in which the light transmittance is controlled by using the image.

In recent years, as a liquid crystal panel forming a light bubble, in contrast to a simple matrix type liquid crystal panel, a TFT type liquid crystal panel in which the transmittance of each pixel is controlled by a transistor is often used. In the case of a panel, image data input for display can be held for one filled period using an IC circuit for data drive. for that reason,
The illumination light of the backlight can be used effectively, and a display device with high contrast and high brightness can be constructed. However, there is a problem that moving image blur occurs in a moving part.

As a method for improving the response speed of the liquid crystal in order to cope with the blur of the moving image as described above, a method of reducing the cell gap of the liquid crystal, a method of using a material having low viscosity,
A method of using at a high temperature may be considered. VA mode, OCB mode and the like are considered as modes for increasing the response speed.
It is possible to set the response speed to 7 ms or less.

[0005]

However, in active matrix driving, it is difficult to eliminate moving image blur with a so-called hold type display regardless of the response speed. Hereinafter, this point will be described with reference to FIG. As shown in FIG. 13A, for example, a white moving sign Q of 4 × 8 pixels is provided on a part of the relatively dark display screen S.
Is displayed, and it is assumed that the movement sign moves in the horizontal direction at the same time as the passage of time.

[0006] In this case, in the diagram (b) showing the next display frame screen S1, the moving marker moves four pixels to the right,
In (c) showing the next frame screen S2, it is assumed that the image is further shifted to the right by four pixels. Assuming that the cycle of one frame is 1/60 sec, the meshed area q1 is displayed for one frame period on the screen S1 and changes from white to black on the next frame screen. Is left as an afterimage and is not recognized as black. Similarly, in the next frame screen S2, the mesh area q2
Is recognized as substantially black, but the mesh portion q2 is not recognized as black.

[0007] According to experiments, it is said that such a visual integration effect is that light stimuli within a short period of time, usually within several tens of milliseconds, are almost completely integrated. When an active drive method of a liquid crystal panel that rewrites image data in units of one frame (one field) is adopted, such a stimulus within a time period is such that the outline of the moving sign Q follows the front and rear of the moving direction. There is a problem that blurred moving image blur occurs.

[0008]

According to the present invention, in order to solve the above-mentioned problems, the invention according to claim 1 includes a plurality of gate lines and a plurality of data lines, and a plurality of gate lines and a plurality of data lines. A liquid crystal panel composed of pixel cells arranged in a matrix corresponding to the intersections, and an image for selecting the gate line and displaying an image on the data line for displaying an image on the liquid crystal panel A liquid crystal display device comprising: a driving unit for supplying a signal; and a lighting unit for illuminating a part of the liquid crystal panel by blinking the liquid crystal panel in correspondence with a cycle of driving the driving unit.

The driving means of the liquid crystal panel is driven so that data is input in a line-sequential manner, and the illuminating means is turned on and off according to the line-sequential driving timing.
In this case, after a part of the liquid crystal panel is driven by the driving means, a lighting timing at which the lighting means illuminates the driven part of the liquid crystal panel is delayed by a predetermined time.

[0010] The delay of the lighting timing satisfies the following expression so that the decrease in luminance is minimized. Δt = (1−duty) × F where Δt: delay of lighting timing duty: duty of blinking of lighting means F: time required for driving means to drive one field of image signal

When the response speed of the liquid crystal panel is taken into consideration, the following equation is satisfied together with the number of divisions of the liquid crystal. τ <(1−duty−A) × F where τ: response time of the liquid crystal A: ratio of the illumination range of the illumination means to the vertical direction of the liquid crystal panel

The illuminating means is a line light source which is always lit during operation, and a liquid crystal shutter which is disposed between the line light source and the liquid crystal panel and controls flickering of the luminous flux of the line light source. It is preferable to use a reflective polarizing plate. Also, as the illuminating means, a reflecting plate for reflecting and converging the light source in one direction, a condensing means for converging a light beam from the reflecting plate in a linear manner, and deflecting a direction of the light beam converged by the condensing means. Alternatively, a device having a deflecting means for irradiating the liquid crystal panel can be used.

[0013]

FIG. 1 is a block diagram showing an outline of a display device according to an embodiment of the present invention. In this figure, reference numeral 10 denotes a TFT type liquid crystal panel which controls the light transmittance of each pixel by applying a voltage to, for example, both terminals of a TN cell in order to display an image. The control electrode is constituted by a finely processed TFT (thin film transistor), and a backlight 20 using a fluorescent lamp as a light source is usually provided on the back surface.

The TFT type liquid crystal panel 10 has the following features.
At the intersections of the scan electrodes and the data electrodes arranged in a matrix, driving is performed so that the image data applied to the thin film transistor is held for one field period. Therefore, the light source of the backlight can be effectively used, and the contrast and the luminance can be increased.

Reference numeral 11 denotes a synchronizing signal generator for extracting a synchronizing signal from image information supplied from, for example, a personal computer or a video source (not shown). The synchronizing signal generator 11 includes at least a horizontal synchronizing signal and a vertical synchronizing signal. Is supplied to the next timing generation unit 12. Reference numeral 13 denotes a scan driver that receives a signal from the timing generation unit 12 and forms a scan signal for the liquid crystal panel 10, and 14 denotes a data driver that also supplies horizontal image data based on a clock supplied from the timing generation unit 12. It is. Reference numeral 15 denotes, for example, when a video signal is supplied as an analog signal, the signal is converted into digital data, and various graphic data and character data are read from a memory to generate an image signal to be displayed, and a predetermined timing is generated. And supplies it to the next signal processing unit 16.

The signal processing unit 16 is a signal processing unit that performs signal processing related to display of a luminance level, a hue, a contrast, and the like according to the display characteristics of the liquid crystal panel 10. Then, the image data appropriately corrected by the signal processing unit 16 is supplied to the data driver 14, and the data is written to the liquid crystal panel line by line, and is normally held for one field period.

Reference numeral 17 denotes a control unit (CPU) for performing overall control of the image display device of the present invention.
7, the display image can be enlarged, reduced, and various other display modes can be selected. Reference numeral 18 denotes a backlight driver for controlling the backlight of the liquid crystal panel. When the backlight 20 includes a plurality of fluorescent lamps L1, L2,. The control is performed such that the lamps are sequentially illuminated and divided into a plurality of regions so that the display surface can be irradiated at a predetermined timing.

Reference numeral 19 denotes a mode switching unit for changing the driving mode of a plurality of backlights as necessary, but this is not always necessary. Further, the video signal generating unit 15 is provided with a motion detecting unit 15A for detecting the motion of the supplied video signal, and the data of the motion detection is transmitted to the control unit 1.
7 to change the lighting mode of the backlight. Further, by providing the RAM 16A, data for signal processing may be externally rewritten.

FIG. 2A shows five fluorescent tubes L1, L2, L
FIG. 3 is a schematic view of a backlight (back light source) 20 configured by 3, L4, and L5 as viewed from the side. Each fluorescent tube L
1, L2, L3, L4, and L5 are arranged along a horizontal line on the back of the display unit 10 composed of a liquid crystal panel, and include five fluorescent tubes and a reflector provided as necessary. Areas B1 and B obtained by dividing display unit 10 into five in the vertical direction
2, B3, B4, and B5 are arranged so as to irradiate substantially uniform light from the back surface. The number of divisions of the display surface can be arbitrarily determined within a range of about 2 to 10.

FIG. 2B shows another embodiment of the backlight, which is a plate-like reflecting plate m1, m2, obliquely oblique to the five fluorescent tubes L1, L2, L3, L4, L5. m3, m4, m5
And the light emitted from each of the fluorescent tubes L1, L2, L3, L4, L5 is reflected upward. In this case, the thickness of the backlight 20 can be reduced as compared with FIG. Normally, a light diffusing plate is arranged on the lower surface of the display unit 10 as shown in the figure, so that the illuminance on the display surface becomes uniform.

FIG. 3 shows a state in which the display surface S of the liquid crystal panel 10 illuminated by the backlight 20 as described above is divided into blocks B1, B2, B3, B4, and B5. By dividing the display surface S in the vertical direction and irradiating the display surface S in a time-division manner at a predetermined timing, it is possible to reduce moving image blur which is one of the objects of the present invention.

FIG. 4 shows an example of a backlight driver for driving each of the fluorescent tubes L1, L2, L3, L4, L5. The frame synchronization signal Sb supplied from the timing generation unit 12 described above is supplied to five delay circuits 13a, 13a,. Parts 13b, 13b,
・ ・ Supplied to Each backlight power supply 13b is activated by a signal delayed for a predetermined time, and supplies a power supply voltage for lighting a fluorescent lamp for a predetermined period (pulse duty) to each of the fluorescent tubes L1, L2, L3, L4, L5. .

Normally, each fluorescent tube L1, L2, L3, L4, L5
Are driven to turn on sequentially from top to bottom, and then repeat extinction. However, as described later, the delay amount of each field delay circuit is controlled based on motion detection, and each backlight power supply is controlled. It is preferable to control the output so that various lighting modes can be set. When moving image blur is eliminated, the lighting time (duty) of each fluorescent tube is shorter than that of a conventional constantly illuminating fluorescent tube. However, as described later, the same luminance can be realized with the same power by selecting the power supply voltage so as to increase the light emission luminance.

FIG. 5 shows the writing timing of the liquid crystal panel and the lighting timing of the fluorescent tubes when three fluorescent tubes are used to irradiate the liquid crystal display surface in three divided areas. Assuming that the number of horizontal lines of the liquid crystal is m, the first area B1 is “1 to m / 3”, and the second area B2 is “(m / 3) +1 to 1”.
2m / 3 "and the third area B3 is" (2m / 3) +1 to 1
It is divided into "m" horizontal (scan) lines. Image data is sequentially captured from horizontal line 1 to horizontal line m at a frame period F (for example, 1/30 ms to 1/120 ms). The response time τ of each line until the liquid crystal molecules physically respond to the captured image data and exhibit a light transmission characteristic corresponding to the image data (hereinafter referred to as a rising response speed) is the final response time of each block. Shown on horizontal lines m / 3, and 2 (m / 3), and the last line m of the field. This rise response speed τ
Is set to a short time on the drawing, but the current T
In the case of an FT type liquid crystal panel, it can be considered that it is actually several ms to several tens ms.

In the first area B1 "1 to m / 3", the first area
A drive signal SL1 for turning on the first fluorescent tube L1 is generated at least at a time point Δt longer than the liquid crystal rising response time τ from a time point f1 when the data capture to the last horizontal line m / 3 in the region of FIG. I do. Then the second
The fluorescent tube L2, which is the backlight light source of the display section in the area B2, is supplied with a signal SL2 which is also delayed by Δt from the time point f2 when the data capture to the last horizontal line 2 (m / 3) in the second area is completed. It is activated and irradiation of the second area B2 is performed. Similarly, the third area B3 is located after the time point f3 at which data is taken in the last horizontal line m of the third area.
After Δt, the fluorescent tube L3 is activated by the signal SL3.

The response time until the liquid crystal molecule rises after the data is captured and the light transmittance reaches a predetermined value, that is, the rise response time τ of the liquid crystal is determined by the rise time of the liquid crystal molecule when the above data is rewritten. Considering that the response time is equal to the falling response time, Δt is preferably Δt ≒ (1−duty) × F. Here, F: field time, duty: irradiation time / F, and conversely, the response speed τ of the liquid crystal is τ <(1-duty−1 / n)
XF is preferred. Here, 1 / n = A indicates the ratio of the illumination range at a certain time to the vertical size of the effective screen.

For example, duty: 50%, block division number n
In the case of = 5 and one field time of 17 mS, the response speed of the liquid crystal is desirably 5 mS or less from the above equation. Under this condition, it is possible to design so as to eliminate moving image blur without considering the response speed of the liquid crystal. .

When the response speed of the liquid crystal is slow, it can be dealt with by reducing the backlight emission duty or increasing the number of divisions of the display surface. Actually, the response speed of the liquid crystal rises and falls rarely equal, and the response speed may not satisfy the above condition. For example, in the case of the normally white TN mode, the transmittance rises slowly and falls quickly. In this case, the rise blur is improved by appropriately increasing Δt as compared with the previous value.

The fall of the signal SL indicating the drive signal of each fluorescent tube is made immediately before the data of the block is rewritten in the first line, more specifically, immediately before the transmittance of the liquid crystal of the line responds to new image data. It can be kept lit, and the period in which the signal SL is shaded is an area that overlaps with the emission period of the fluorescent tube in the adjacent block. Therefore, in the above embodiment, the duty for lighting the fluorescent tube is set.
{TB1, TB2, TB3} is 1/3 of one frame period
The length can be longer, and sufficient luminance can be given to the liquid crystal panel. However, when the fall is slow, Δt is shortened as compared with the previous value, but these fine adjustments may be adjusted according to the response characteristics of the liquid crystal.

It is ideal that the light emitted from the backlight is ideally applied only to the area that divides the display screen, but actually, it is also applied to other blocks of the divided display surface. . For example, when five fluorescent lamps are arranged in parallel as a backlight as shown in FIG. 2 described above, the irradiation light of the second fluorescent tube L2 leaks into the B1 region and the B2 region originally emits. In addition to the light emitted by the fluorescent tube L2 of the backlight, the light emitted by the adjacent fluorescent tubes L1 and L3 leaks. When viewed from the side, the brightness of the light emitted by the backlight is different from the view in time near the boundary of the block depending on the structure of the backlight as shown by each line type in FIG. May be affected by the emission of the backlight.

Therefore, if there is an image showing a fast movement at the boundary of each block on the display surface, the moving image blur will be conspicuous, but in order to reduce this effect, the number of divisions of the display screen is further reduced. By increasing, for example, 10
By dividing, moving image blur can be almost eliminated. Note that when the display surface is divided and the backlight is illuminated as described above, when all the backlights are turned on at the same time, there is no luminance unevenness on the display surface as indicated by the three-dot line. Like the position of the backlight,
By disposing the light diffusion plate, even if the backlight is controlled to blink as described above, the brightness of each boundary area of the display surface can be made almost inconspicuous by the integration effect.

By the way, when the number of backlights is increased, generally, the duty of the backlight for irradiating each display surface is increased.
, The brightness of the display screen decreases accordingly. Therefore, it is preferable to increase the light emission power of each backlight so that light emission with sufficiently high luminance is performed even in a short time.

However, when a fluorescent tube is used as a backlight, it is necessary to consider the effect of extinguishing the luminance at high temperatures when the driving power is increased. For example, FIG. 7 shows the relationship between the luminance of a fluorescent tube as a backlight and the power (tube current) supplied to the fluorescent tube. In the case of a fluorescent tube, the luminous efficiency depends on the environmental temperature, and when the tube current increases, the efficiency decreases due to heat generation of the fluorescent tube itself. In the case of a normal fluorescent tube that is set to optimize the efficiency in the low current region, when the ambient temperature is fixed, the luminance decreases as shown by the dotted line when the tube current is increased. . However, when the environmental temperature at which the luminance is optimal is set, the luminance can be increased as the tube current increases, as shown by the thick line in the figure.

In general, when the tube current is increased, the temperature of the fluorescent tube also rises as it is.
When driving is performed, power consumption does not increase only by the magnitude of the tube current. Therefore, if the duty drive is used, it is possible to prevent the luminance from lowering even if the tube current is increased.
In other words, as shown in FIG. 8A, when setting is made so that sufficient luminance is obtained with respect to the environmental temperature of the power Pn at the time of 100% duty (always on), the duty is 50% or 30%.
In this case, as shown in FIG. 11B or 11C, control is performed so that the tube current increases at the time of driving, so that the average value of luminance can be increased. In this case, since the average power Pn does not change and the tube temperature does not rise so much, the light emission luminance can be sufficiently increased.

FIG. 9 shows an embodiment in which, when the backlight is applied to each of the divided regions of the liquid crystal panel, the irradiation light is intermittently switched by the liquid crystal shutter.
In this figure, the backlight 20 has L1, L2, L
3, consisting of four L4 fluorescent tubes,
Above it, a liquid crystal shutter 30 is provided. As is well known, the liquid crystal shutter 30 has polarizing plates 30A and 30B disposed vertically above and below a liquid crystal plate, and driving electrodes of the liquid crystal shutter are divided into divided regions B1, B2, and B of the liquid crystal panel.
3 and B4 are arranged by transparent electrodes or the like. Therefore, when the voltage applied to the transparent electrode is supplied at the timing of the signal SL, the irradiation light to the liquid crystal panel can be irradiated at a predetermined timing for each of the divided regions B1, B2, B3, and B4.

FIG. 10 shows another embodiment of the backlight when the above-mentioned liquid crystal shutter is used. In this embodiment, a liquid crystal shutter 30 is disposed above a light source section 20 of a backlight, and a liquid crystal panel 10 is mounted above the liquid crystal shutter 30 via a light diffusion plate. The polarizers of the liquid crystal shutter 30 are reflective polarizers 30c and 3
0d are arranged on both surfaces of the liquid crystal, and drive electrodes of the liquid crystal shutter 30 are provided corresponding to the divided areas of the liquid crystal panel 10 as in the case of FIG. The light source unit 20 may be provided with a fluorescent tube inside since the entire inner surface of the light source unit 20 is surrounded by a reflection plate. Alternatively, the light source unit 20 may include a surface-emitting type light source.

The reflective polarizers 30 (c, d) have the property of transmitting light of a specific plane of polarization but reflecting light that does not match the plane of polarization, for example, s-wave without absorbing it.
Then, from the area where the shutter is open, for example, the p-wave is transmitted to irradiate the liquid crystal panel, and the light in the area where the shutter is closed is totally reflected by the s-wave toward the light source unit 20 as shown in FIG. At 20, the light whose polarization plane has been rotated is emitted toward the liquid crystal panel from the region where the shutter is open again. Therefore, the light transmitted through the liquid crystal shutter increases, the light from the light source unit 20 can be used effectively, and the luminance of the irradiation light is increased as compared with the case where a reflection type normal polarizing plate is used. Can be. In addition, since the polarizing plate does not absorb light, heat resistance can be added.

Such a reflective polarizing plate is, for example, 3M
It has been put to practical use as DBEF (trade name), and it is possible to add heat resistance by attaching it to a rear polarizing plate of a liquid crystal panel in the form of a polarizing film, and to share the polarizing plate on the front side of the liquid crystal panel. Increase compatibility with liquid crystal display devices.

FIG. 11 shows an embodiment of a backlight 30 using a light source 31 which is a point light source or a line light source.
The illumination type backlight shown in this figure is one in which a high-luminance light source (metal halide lamp) 31 can be used. The light emitted from the light source 31 is made substantially parallel by the elliptical reflector 32, and narrowed down linearly by the cylindrical lens 33. Reference numeral 34 denotes a polygonal rotating mirror (polygon mirror), which reflects a light beam linearly narrowed down by the cylindrical lens 33 toward the liquid crystal panel 10 via the diffusion plate 10A and irradiates it.

When the rotation phase and the number of rotations of the rotating mirror 34 are controlled in accordance with the frame period of the image displayed on the liquid crystal panel 10, a light beam can be applied to a hatched area. A backlight that irradiates the entire surface of the liquid crystal panel in a time-division manner by moving the light beam portion in the arrow direction is configured. This embodiment can be used as a backlight of a liquid crystal panel (liquid crystal projector) for projecting an image on a screen because the backlight can have high brightness.

In each of the above embodiments, the case where a fluorescent tube is mainly used as a light source has been described. However, as a light emitting source, a PDP which is a flat type display device recently developed is used.
(Plasma display panel) may be used. In addition, when an organic EL plate that is practically used as a flat light source is used as a surface light emitting source, it is possible to extremely easily control the emitted light that irradiates the divided area of the liquid crystal panel.

Further, when a surface light source is formed by arranging high-intensity light-emitting diodes in a flat plate shape and arranged on the back of the liquid crystal panel, the light-emitting area and the light-emitting timing can be easily controlled by using a control pulse of a scan driver. Will be able to do it.

When the motion of the image to be displayed is detected by the motion detector 15A as shown in FIG. 1, the blinking mode of the backlight can be changed in accordance with the detection result. it can. For example, in the case of a still image in which the display screen does not move, the flashing control of the fluorescent tubes constituting the backlight is changed to the full lighting mode by the signal output from the mode switching unit 19 in FIG. 1 during that period. Alternatively, high-luminance display is enabled by controlling all the shutter areas of the liquid crystal shutter to be open.

Further, control may be performed so that the number of divisions of the area displaying the screen is changed according to the degree of movement. For example, the number of fluorescent tubes in the backlight is increased, and the emission timing of each fluorescent tube is determined so as to increase the number of divisions of the display surface in the case of an image that moves extremely, and the image is divided in a scene with little movement. The light emission timing of the fluorescent tube is controlled so as to reduce the number, and the light emission luminance is controlled at the same time. Such control is performed by controlling the field delay circuits 13a and the backlight power supply 13b shown in FIG.
May be performed based on the command signal from

FIG. 12A shows another embodiment of a backlight applicable to the display device of the present invention. In this figure, 21A and 21B are light sources composed of a fluorescent tube, a halogen lamp or the like, and 22 is a light guide plate formed of an acrylic resin or the like. Light guide plate 22
The reflection plate 23 is provided on one surface, and a liquid crystal panel as a display device is disposed on the other surface.

At the center of the light guide plate 22, there is buried a liquid crystal plate 24 whose isotropic light transmission characteristics change to anisotropic light transmission characteristics when a voltage is applied. The liquid crystal plate 24 is made of, for example, a nematic liquid crystal having a positive dielectric anisotropy, and its arrangement direction is parallel to the light guide direction.
One surface is used as a common electrode, and the other surface is formed with striped electrodes (both transparent electrodes).
From the region Lw of the electrode portion to which the voltage is applied, the light guide plate 22
Light source 21 traveling in a zigzag manner while reflecting inside
The light of (A, B) is taken out. Such an optical element is called an H-PDLC (holographic polymer laser paste crystal).

FIG. 12B is an enlarged view of a part of the light guide plate 22, and the liquid crystal plate 24 is divided by electrodes in the horizontal direction at fine intervals like the liquid crystal panel. That is, the lower surface is a common electrode surface 28, but a large number of stripe electrodes 27 are formed on the upper surface at intervals of several microns in the horizontal direction, and the stripe electrodes 27 are divided into blocks corresponding to the number of divisions of the display device and drawn out. Like that. When no voltage is applied to the upper and lower electrodes of the liquid crystal plate 24, the light guide plate 22 has an isotropic transmission characteristic, and light emitted from the light sources 21A and 21B is transmitted to the upper and lower surfaces of the light guide plate 22. The light source 12 (A, B) reciprocates as shown in FIG.

However, when a voltage is applied to a certain region Lw of the liquid crystal plate 24, the liquid crystal molecules in this region 26 are shifted in a stripe shape as shown in FIG. The regions form, for example, a diffraction grating for p-polarized waves. Then, the light passing through the diffraction grating portion is anisotropic, so that light entering from one side changes its course upward and light entering from the other direction changes its course downward. However, although the s-polarized wave is guided as it is, polarization information is lost by repeating reflection and refraction by the light source and the reflector, and the s-polarized wave is again incident on the light guide plate from the other end. The p-polarized wave reflected upward, for example, irradiates the divided area of the liquid crystal panel as it is, and the polarized wave reflected downward is also reflected by the reflection plate 23, so that the liquid crystal panel side is irradiated.

By setting the selection pattern of the stripe electrodes 27 in accordance with the divided display area of the liquid crystal panel, a backlight which can irradiate an arbitrary portion of the liquid crystal panel with light can be constituted. When the reflecting plate 23 on the rear surface is deformed into a mountain shape as shown in FIG. 9C, parallel light in the light guide plate 22 also repeats total reflection in a zigzag manner, so that more outgoing light can be obtained. . Further, since only light having a uniform polarization direction is emitted from the backlight of this embodiment, it is suitable as illumination light for a liquid crystal display device.

[0050]

As described above, the liquid crystal display device of the present invention divides the display surface of the transmissive liquid crystal panel into predetermined regions and irradiates the divided regions with light at a predetermined timing. In particular, in the case of a TFT type liquid crystal display device which is required to have high contrast and high brightness, there is an effect that blurring due to moving images can be almost eliminated.

[Brief description of the drawings]

FIG. 1 is a block diagram of a liquid crystal display device showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a backlight to which a fluorescent tube is applied.

FIG. 3 is a schematic diagram showing an overall view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 4 is a block diagram showing a driving system of a backlight.

FIG. 5 is a waveform diagram showing timings of writing data on a liquid crystal panel and turning on and off a backlight.

FIG. 6 is an explanatory diagram showing a luminance distribution of a backlight when divided into five parts.

FIG. 7 is a graph showing a relationship between luminance of a fluorescent tube and power consumption.

FIG. 8 is an explanatory diagram of electric power when the backlight is driven at a predetermined duty.

FIG. 9 is an explanatory diagram when a liquid crystal shutter is used for controlling a backlight.

FIG. 10 is a side view showing a combination of a liquid crystal shutter and a reflective polarizing plate.

FIG. 11 is a schematic diagram showing an embodiment when a high-luminance backlight is realized.

FIG. 12 is an explanatory diagram when an H-PDLC is used as a backlight.

FIG. 13 is an explanatory diagram of moving image blur occurring in the liquid crystal display device.

[Explanation of symbols]

Reference Signs List 10 liquid crystal panel, 11 synchronization generator, 12 timing generator, 13 scan driver, 14 data driver, 15 video signal generator, 16 signal processor, 17
Control unit, 18 backlight driver, 20 backlight

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/66 102 H04N 5/66 102B F term (Reference) 2H093 NA16 NA43 NC12 NC34 NC44 NC45 ND02 ND04 ND07 ND08 ND09 NE06 5C006 AF19 BB15 BB16 EA01 FA11 GA02 5C058 AA09 AB03 BA03 BA05 BA29 BA35 BB25 EA26 EA51 5C080 AA10 BB05 DD01 DD07 EE19 FF11 FF12 JJ01 JJ02 JJ04 JJ05 JJ06 KK43 5G435 EA13 GG12 GG13 DD09 DD26

Claims (9)

[Claims] 1. A liquid crystal panel comprising a plurality of gate lines and a plurality of data lines, pixel cells arranged in a matrix corresponding to intersections of the gate lines and the data lines, and an image on the liquid crystal panel. Driving means for selecting the gate line and supplying an image signal for displaying an image on the data line, and displaying a part of the liquid crystal panel in accordance with a cycle of driving the driving means. A liquid crystal display device, comprising: lighting means for blinking and lighting. 2. The liquid crystal display device according to claim 1, wherein the liquid crystal panel is driven line-sequentially by the driving means, and the lighting means is turned on and off in accordance with the line-sequential driving timing. 3. A lighting timing for illuminating a driven portion of the liquid crystal panel by the lighting means after a part of the liquid crystal panel is driven by the driving means is delayed by a predetermined time. 3. The liquid crystal display device according to 2. 4. The liquid crystal display device according to claim 3, wherein the delay of the lighting timing satisfies the following expression. Δt = (1−duty) × F where Δt: delay of lighting timing duty: duty of blinking of lighting means F: time required for driving means to drive one field of image signal 5. The liquid crystal display device according to claim 4, wherein a liquid crystal response speed of the liquid crystal panel satisfies the following expression. τ <(1−duty−A) × F where τ: response time of the liquid crystal A: ratio of the illumination range of the illumination means to the vertical direction of the liquid crystal panel 6. The liquid crystal display device according to claim 1, wherein said illuminating means comprises a plurality of line light sources. 7. A light source comprising: a line light source which is constantly lit while the illumination means is in operation; and a liquid crystal shutter disposed between the line light source and a liquid crystal panel, for controlling blinking of a light beam of the line light source. The liquid crystal display device according to claim 1. 8. A illuminating means for reflecting the light source in one direction and converging the light source, a condensing means for converging a light beam from the reflecting plate in a linear manner, and a light beam converged by the condensing means. 2. The liquid crystal display device according to claim 1, further comprising: a deflecting unit that irradiates the rear surface of the liquid crystal panel so as to scan. 9. The liquid crystal display device according to claim 1, wherein the liquid crystal panel is constituted by an active matrix type liquid crystal panel.