WO2009125600A1 - Unité d'affichage d'image à cristaux liquides - Google Patents

Unité d'affichage d'image à cristaux liquides Download PDF

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Publication number
WO2009125600A1
WO2009125600A1 PCT/JP2009/001658 JP2009001658W WO2009125600A1 WO 2009125600 A1 WO2009125600 A1 WO 2009125600A1 JP 2009001658 W JP2009001658 W JP 2009001658W WO 2009125600 A1 WO2009125600 A1 WO 2009125600A1
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WIPO (PCT)
Prior art keywords
signal
pulse
video
liquid crystal
image
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PCT/JP2009/001658
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English (en)
Japanese (ja)
Inventor
安部玲央
西田保洋
渡辺一幸
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株式会社ナナオ
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Priority to JP2010507178A priority Critical patent/JP5132763B2/ja
Publication of WO2009125600A1 publication Critical patent/WO2009125600A1/fr

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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0237—Switching ON and OFF the backlight within one frame
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0247—Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0261—Improving the quality of display appearance in the context of movement of objects on the screen or movement of the observer relative to the screen
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0626—Adjustment of display parameters for control of overall brightness
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/10—Special adaptations of display systems for operation with variable images

Definitions

  • the present invention relates to a liquid crystal image display device, and more particularly to a lighting method of a backlight, and relates to a technique for appropriately generating a light control signal of the backlight according to the movement of a video image.
  • the batch intermittent lighting method in which all backlights are lit collectively and the backlight are divided into several phases, and the backlights of each phase are sequentially lit according to the writing of liquid crystal pixels.
  • CFF critical fusion frequency
  • this critical fusion frequency becomes high due to the conditions under which the liquid crystal display is viewed, the enlargement of the liquid crystal display and the increase in luminance.
  • the critical fusion frequency was previously said to be lower than 60 Hz, but has recently exceeded 60 Hz. From this, flickering is felt when it is intermittently turned on in synchronization with the vertical sync signal of 60 Hz in a still image.
  • the Weber's law in the discrimination of brightness is that the ratio of ⁇ S to S, ⁇ S / S, is constant. According to this law, when the frequency of the dimming pulse is instantaneously switched, the amount of change in the amount of light accumulated in the human eye becomes equal to or greater than ⁇ S along with the instantaneous change in luminance. Are felt.
  • the solid line is the luminance emitted by the light source
  • the broken line is a square wave of the dimming pulse.
  • the amount of change in integral of the luminance at the transition of the pattern from high frequency to low frequency is equal to or greater than ⁇ S of Weber's law, and it can be perceived by the human eye as an instantaneous luminance change.
  • Patent Document 1 and Patent Document 2 still have the following unsolvable problems. This problem arises from the fact that the number of dimming pulses in a unit vertical synchronization period is different for each type of frequency because there are multiple types of frequencies of dimming pulses.
  • the number of falling of the dimming pulse in the unit vertical synchronization period is different before and after the switching of the dimming pulse. That is, the number of fall of the dimming pulse in the unit vertical synchronization period is different between the moving image determination and the still image determination.
  • Patent Document 1 when the light adjustment pulse at the time of moving image judgment is 60 Hz, the number of falling of the light adjustment pulse in the unit vertical synchronization period is one, and when the light adjustment pulse at the still image judgment is 240 Hz The number of falling of the dimming pulse in the unit vertical synchronization period is four. As a result of the difference in the number of falling edges of the dimming pulse, when the moving image determination and the still image determination are compared, chromaticity change and luminance change constantly occur on the screen.
  • a fluorescent tube is usually used as a backlight of a liquid crystal image display device.
  • Red, green, and blue phosphors are applied to the inner surface of the glass of the fluorescent tube, and the green phosphor has an afterglow characteristic that the afterglow time is longer than that of other reds and blues.
  • a green afterglow occurs. That is, the number of times of occurrence of the green afterglow is different in each image judgment because the number of falling of the light adjustment pulse in the unit vertical synchronization period is different between the moving image determination and the still image determination.
  • the whole screen has a greenish chromaticity than the moving image determination.
  • the luminance has a non-linear waveform.
  • the luminance is a non-linear curvilinear wave. From this, even if the duty ratio per unit vertical synchronization period of each frequency is the same, the luminances do not match. Even if the duty ratio is the same, the luminance is not simply superimposed, so the screen with a high frequency is slightly lower in luminance than the screen with a low frequency. That is, the brightness of the screen at the still image determination with the narrow pulse width and the large pulse number is darker than that in the moving image determination with the wide pulse width and one pulse number, even if the duty ratio is the same. As a result, when the luminances of the moving image determination, the still image determination, and the screen are compared, the entire screen becomes slightly darker at the still image determination.
  • the present invention has been made in view of such circumstances, and the lighting mode of the backlight is instantaneously changed in luminance (flushing phenomenon) when switching between a moving image and a still image, and steady before and after the switching. It is an object of the present invention to provide a liquid crystal image display device which does not display image contour blurring at the time of moving image and flicker at the time of still image without causing any luminance change and chromaticity change.
  • a light control signal consisting of a pulse train formed of a plurality of predetermined pulses and a video judgment means for transmitting a video judgment signal predetermined based on the video signal is vertical It comprises: a light control signal generating unit that generates each synchronization signal; a light emitting unit driven by the light control signal sent from the light control signal generating unit; and a liquid crystal image display unit that emits light by the light emitting unit.
  • the light adjustment signal generation means when the first image discrimination signal is sent from the image discrimination means, maintains the number of pulses constituting the light adjustment signal, and the pulse interval in the pulse train is maintained.
  • the pulse interval in the pulse train is set while maintaining the number of pulses constituting the light adjustment signal. Gradually Characterized by widely.
  • the liquid crystal image display device of the present invention in order to shift the lighting method of the backlight to either the moving image mode or the still image mode by the video image discrimination signal sent based on the video signal, every vertical synchronization period The phase of each pulse generated in the same number is displaced. That is, the moving image mode and the still image mode are switched by adjusting the interval of each pulse in the pulse train. It is a feature of the present invention to adjust the intervals of a plurality of pulses generated in the same number in the unit vertical synchronization period.
  • the number of pulses in the unit vertical synchronization period is the same in both modes, the number of falling edges of the pulse in the unit vertical synchronization period is the same. Therefore, since the green afterglow characteristics of approximately the same amount appear in either mode, the change in chromaticity upon switching between the moving image mode and the still image mode is largely suppressed. In addition, since the number of falling edges of the pulse in the unit vertical synchronization period is the same, the non-linear waveform of the backlight is the same, and the steady luminance change at the time of switching between the moving image mode and the still image mode is significantly suppressed. .
  • the chromaticity change and the luminance change are reduced to such an extent that a human does not feel a change by appropriately setting the pulse interval in the moving image mode.
  • the progressive change described in claim 1 notices the change of the mode switching with the human eye. It also means adjusting the pulse interval steplessly to the extent that it can not
  • the dimming signal generation means gradually narrows the pulse interval in the pulse train while maintaining the number of pulses constituting the dimming signal.
  • a pulse train formed by a plurality of pulses can be regarded as one pulse in a pseudo manner, and when the second image discrimination signal is sent from the image discrimination means, a light control signal is formed.
  • the pulse train is equivalent to a pulse train represented by a frequency obtained by multiplying the number of pulses in the dimming signal by the number of pulses in the dimming signal by gradually widening the pulse interval in the pulse train while maintaining the number of pulses. It is desirable to make it
  • the pulse train formed from a plurality of pulses shifts to a moving image mode in which it is regarded as one pulse in a pseudo manner. Then, when an image discrimination signal different from the above is sent, the interval of the pulses in the pulse train is gradually extended, and the pseudo one pulse is shifted to the independent pulse. Then, in the still image mode, the phase of the pulse having the widest pulse interval in the dimming signal becomes the same phase as the pulse of the frequency obtained by multiplying the number of pulses in the unit vertical synchronization period by the vertical synchronization frequency. . From this, at the time of switching from the moving image mode to the still image mode, and at the reverse switching time, the instantaneous luminance change (flushing phenomenon) of the backlight is eliminated.
  • the pulse train is virtually regarded as one pulse, and the lighting period and the lighting-off period of the fluorescent tube are approximately divided into two within the unit vertical synchronization period,
  • the continuous black insertion period within the unit vertical synchronization period becomes long. Thereby, the image outline blurring of a moving image can be reduced.
  • the video discrimination means discriminates whether the video is a video which is not likely to sense flicker or is a video which is likely to sense a flicker based on the video signal, and when it is determined that the video is unlikely to sense flicker, the first video discrimination signal
  • the second image discrimination signal may be transmitted when it is determined that the image is transmitted and flicker is easy to feel. From this, the image discrimination means discriminates whether the image is an image which is easy to sense flicker or not so as to send each image discrimination signal, so that the image displayed on the liquid crystal image display device can be displayed.
  • a suitable backlight can be lit.
  • the light adjustment signal generation unit may be provided with a screen brightness adjustment signal reception unit that adjusts the brightness of the liquid crystal screen by adjusting the pulse duty ratio of the light adjustment signal by receiving the screen brightness adjustment signal.
  • a screen brightness adjustment signal reception unit that adjusts the brightness of the liquid crystal screen by adjusting the pulse duty ratio of the light adjustment signal by receiving the screen brightness adjustment signal.
  • the adjustment of the brightness of the liquid crystal screen is performed by changing the duty ratio of the pulse forming the dimming signal, the switching between the moving image mode and the still image mode of the dimming signal and the adjustment of the brightness of the screen are performed. Can be performed by one dimming signal generation circuit.
  • the light emitting means may have a plurality of light sources, and the lighting method of the light sources may be an intermittent lighting method in sequence.
  • the lighting method of the light sources may be an intermittent lighting method in sequence.
  • the light emitting means may comprise a light source consisting of three or more layers. Since the liquid crystal display is controlled by the sequential intermittent lighting of three or more layers even in the case of a large screen, it is possible to efficiently reduce the image outline blurring of a moving image.
  • liquid crystal image display device According to the liquid crystal image display device according to the present invention, instantaneous luminance change (flushing phenomenon) does not occur at the time of switching between the moving image mode and the still image mode of the backlight. In addition, it is possible to provide an image in which steady change in chromaticity and change in luminance before and after switching are significantly suppressed.
  • FIG. 1 is a block diagram showing a schematic configuration of a liquid crystal image display device according to a first embodiment.
  • FIG. 2 is a block diagram showing a schematic configuration of a video image discrimination circuit provided in the first embodiment.
  • FIG. 2 is a block diagram showing a schematic configuration of a light adjustment signal generation circuit provided in the first embodiment.
  • FIG. 2 is a block diagram showing a schematic configuration of a backlight module provided in the first embodiment.
  • FIG. 5 is a schematic view showing a dimming signal generated in the dimming signal generation circuit of the first embodiment. 5 is a flowchart showing a process of calculating pulse intervals in a pulse interval calculation unit provided in the dimming signal generation circuit of the first embodiment.
  • FIG. 1 is a block diagram showing a schematic configuration of a liquid crystal image display device according to a first embodiment.
  • FIG. 2 is a block diagram showing a schematic configuration of a video image discrimination circuit provided in the first embodiment.
  • FIG. 2 is a block diagram showing a
  • FIG. 7 is a diagram showing dimming signals generated in the moving image mode in the three dimming signal generation circuits of the first embodiment. It is the figure which compared the light control signal of the backlight in Example 1 and a prior art example, and the brightness perceived through a liquid crystal panel.
  • FIG. 6 is a diagram showing luminance and chromaticity in a moving image mode and a still image mode of the first embodiment. It is a figure which shows the brightness
  • FIG. 1 is a block diagram showing the configuration of the liquid crystal image display device according to the first embodiment.
  • This device determines whether the image is a video that does not easily sense flicker or a flicker based on a video signal and sends out a video discrimination signal, and an optimal dimming according to the image based on a video discrimination signal.
  • a light control signal generation circuit 3 for generating a signal, a backlight module 5 for emitting a backlight by the light control signal, and a liquid crystal panel 7 for emitting light by the backlight module 5 to display an image.
  • Video discrimination circuit 2 calculates the sum of image differences between the signal of the previous frame image 10 and the signal of the current frame image 8 based on the image signal branched from the image signal sent to the liquid crystal panel 7 It asks with the vessel 9. This operation is a function included in a general video processing IC, and this embodiment is also used. Next, by comparing the sum of the differences of the image signals with the threshold set in advance by the discriminator 11, it is determined whether the current frame image 8 is a video that is hard to sense flicker or a video that is prone to flicker Make a decision.
  • a signal of '1' (moving image) is sent as a video discrimination signal, and when it is discriminated that the video is easy to feel flicker, '0' (still image Send a signal of).
  • the light control signal generation circuit 3 is instructed to determine whether the video image is a moving image or a still image.
  • the video is a moving image, it is difficult to sense flicker, and if it is a still image, flicker is likely to be felt.
  • moving pictures and still pictures are mixed in the display screen in practice, and if moving pictures are included in the display screen, it can not be immediately determined to be moving pictures.
  • a video that is hard to sense flicker means a video that is substantially moving.
  • a substantially moving image refers to a moving image as a whole, even if a part of the screen includes a non-moving image.
  • an image that is susceptible to flicker means an image that is substantially motionless.
  • a substantially motionless video refers to a video that has no motion as a whole, even if the portion of the screen includes a motional video.
  • the dimming signal generation circuit 3 generates an optimal dimming signal according to the image in accordance with the image discrimination signal.
  • three parameters of pulse interval, duty ratio, and pulse generation timing are calculated to generate a dimming signal.
  • a three-phase dimming signal is sent to the backlight module. The generation of the dimming signal will be described in detail later.
  • the backlight module 5 includes light sources 23a, 23b, 23c and inverters IC 21a, 21b, 21c for controlling them.
  • a light source in the present embodiment, two CCFL tubes are provided for each light source. That is, the backlight module 5 has a total of six CCFL (Cold Cathode Fluorescent Lamp) tubes.
  • CCFL Cold Cathode Fluorescent Lamp
  • the respective dimming frequencies are synchronized by the respective inverters IC 21 a, 21 b and 21 c. Have control.
  • the light sources 23a, 23b, and 23c are intermittently turned on one after another to illuminate the liquid crystal panel 7.
  • the number of fluorescent tubes, the number of fluorescent tubes to be controlled by the inverter IC, and the like may be determined by a designer who is considered to be optimum.
  • the liquid crystal panel 7 includes a drive circuit of the liquid crystal panel, and uses an active matrix liquid crystal display panel using thin film transistors (TFTs).
  • TFTs thin film transistors
  • the illumination of light from the backlight module 5 adapted to the video signal makes it possible for the viewer not to feel a momentary change in luminance when switching between the moving image mode and the still image mode.
  • a comfortable video can be provided without the viewer being able to feel a steady change in chromaticity and a change in luminance before and after switching.
  • Dimming signal generation circuit 3 The operation of the dimming signal generation circuit 3 will be described below.
  • the video discrimination signal sent out by the video discrimination circuit 2 is taken into the pulse interval calculation unit 13, and the pulse interval of the pulse train in the dimming signal is calculated frame by frame by the vertical synchronization signal and the video discrimination signal.
  • the pulse interval means the interval between each pulse forming the pulse train within the unit vertical synchronization period.
  • the number of pulses of the pulse train of the dimming signal in the unit vertical synchronization period is three.
  • the pulse train forming the dimming signal has the same phase as the pulse train generated at a frequency of 180 Hz.
  • the vertical synchronization frequency is 60 Hz in the case of the NTSC signal standard.
  • the number of pulses of the pulse train in the unit vertical synchronization period is not limited to three and may be plural.
  • the pulse train of the dimming signal in the still image mode is the same as the pulse train generated at the frequency of (number of pulses) ⁇ (vertical synchronization frequency). Furthermore, it is preferable that (number of pulses) ⁇ (vertical synchronization frequency) exceeds the critical fusion frequency.
  • the pulse interval calculation unit 13 has the smallest pulse interval, the most suitable moving image mode for moving image display (FIG. 5 (b)), and the largest pulse interval, the most suitable still image mode for still image display (FIG. 5). 5 (d) and the interval between the light control pulses of the four states of moving picture mode transition state from still picture mode to moving picture mode transition state and vice versa transition state from moving picture mode to still picture mode calculate.
  • the dimming signal having the smallest pulse interval can be regarded as pseudo in that a pulse train formed by three pulses is formed by one pulse.
  • a pulse train with the same phase as three independent pulses at 180 Hz in still image mode can be regarded as one pulse of 60 Hz in a pseudo manner by reducing the pulse interval in the pulse train in moving image mode. it can.
  • the fluorescent tube lighting period and the light-off period are approximately divided into two in the unit vertical synchronization period in the moving image mode, backlight irradiation is optimal for moving image display.
  • Pulse interval calculation The flow of pulse interval calculation performed by the pulse interval calculation unit 13 is shown in FIG. In this calculation flow, calculation of the pulse interval is started when the vertical synchronization signal is input.
  • a video discrimination signal is input from the video discrimination circuit 2, in step S1, video discrimination is performed to determine whether the signal is larger than '0'. If the video image discrimination signal is '1' (moving image), the process proceeds to step S2. If the video image discrimination signal is' 0 '(still image), the process proceeds to step S2'.
  • the case where the video image discrimination signal is a moving image and the process proceeds to step S2 will be described.
  • step S2 an operation to reduce the pulse interval is performed.
  • Space is a pulse interval
  • ⁇ X is a pulse interval displacement amount in a unit vertical synchronization period. This ⁇ X is a value determined by the vertical synchronization frequency, the number of pulses, the duty ratio, and the number of frames applied to transition from the moving image mode to the still image mode.
  • the setting amount of the pulse interval displacement amount ⁇ X determines the speed of transition from the moving image mode to the still image mode or transition from the still image mode to the moving image mode.
  • the pulse interval displacement amount ⁇ X is made large, the switching of the mode becomes fast, so that the luminance change due to the instantaneous switching occurs.
  • the pulse interval displacement amount ⁇ X is made small, the mode switching is delayed, so there is a time difference until the flicker disappears while the image is switched from the moving image to the still image, and the image changes from the still image to the moving image Even though the image is switched to the above, there is a time difference until the image outline blurring of the moving image disappears.
  • step S2 since the image discrimination is determined to be a moving image, in step S2, the pulse interval displacement amount ⁇ X is subtracted from the previous pulse interval.
  • step S3 the subtracted pulse interval is compared with a preset minimum value. If the subtracted pulse interval is greater than the minimum value, the subtracted pulse interval is output as the calculated result. As a result, the pulse interval is smaller than that of the previous pulse train, and the light adjustment signal closer to moving image display is approached.
  • the pulse interval subtracted in step S4 is reset to the minimum value, and the minimum value is output as the calculation result.
  • the smallest pulse interval most suitable for moving image display is output as long as the video discrimination signal continues to send '1' (moving image). It is a process to continue.
  • the minimum pulse interval in this moving picture mode differs depending on the frequency of the vertical synchronization signal of the NTSC system, PAL system or the like, the length of the fluorescent tube, and the color gamut.
  • the upper limit is also determined by how much continuous black insertion time (fluorescent tube off time) in the vertical synchronization period is secured in the moving image mode, and the degree of chromaticity before and after switching between the moving image mode and the still image mode
  • the lower limit value is determined depending on whether or not a change occurs, so it is necessary to set appropriately.
  • the upper limit value of the minimum pulse interval in the moving image mode can be determined as follows. When the number of pulses in the pulse train is three, if the continuous black insertion time in the unit vertical synchronization period is 50% of the unit vertical synchronization period and the dimming ratio is 10%, the remaining 40% Can be used as a pulse interval, so that 20% of the unit vertical synchronization period can be a pulse interval per pulse train. If the unit vertical synchronization period is 16.6 msec, 3.32 msec is the upper limit value of the minimum pulse interval. However, as described above, since the upper limit value of the minimum pulse interval is determined by the number of pulses in the pulse train, the black insertion time, and the dimming ratio, it can be set appropriately.
  • the lower limit value of the minimum pulse interval in the moving image mode is a numerical value determined depending on how much chromaticity change is not generated before and after switching between the moving image mode and the still image mode, as described above. Then, it is 0.1 msec or more, more preferably 0.5 msec or more.
  • step S1 When the image discrimination signal '0' (still image) is input in step S1, the process proceeds to step S2 '.
  • the pulse interval displacement amount ⁇ X is added to the previous pulse interval. As a result, an operation to increase the pulse interval is performed.
  • step S3 ' the added pulse interval is compared with a preset maximum value. If the added pulse interval is smaller than the maximum value, the added pulse interval is output as the calculated result. As a result, the pulse interval is larger than that of the previous dimming pulse signal, and the dimming pulse closer to still image display is approached.
  • step S4 If the pulse interval added in step S3 'is equal to or greater than the maximum value, the added pulse interval is reset to the maximum value in step S4', and the maximum value is output as the calculation result.
  • the widest pulse most suitable for still image display after reaching the most suitable pulse interval for still image display, the widest pulse most suitable for still image display as long as the video discrimination signal continues to send' 0 '(still image). It is a process of continuing to output the interval.
  • the maximum value of the pulse interval in the still image mode is a value determined by the vertical synchronization frequency, the number of pulses, and the duty ratio.
  • the pulse interval calculation unit 13 sends the pulse interval to the pulse generation timing control unit 15.
  • the vertical synchronization signal and the duty ratio are sent to the pulse generation timing control unit 15 in addition to the pulse interval.
  • the duty ratio is set by sending a screen brightness adjustment signal of the brightness setting value of the liquid crystal screen display device selected by the user to the screen brightness adjustment signal receiving unit 17.
  • each adjustment is performed such that the pulse phase of each of the light adjustment signal generation circuits 19a, 19b, 19c is shifted by 1/3 period in the vertical synchronization period.
  • the first pulse rise command for light signal generation, trigger 1, trigger 2, trigger 3 is sent out. Since the pulse phases to be sent to the respective dimming signal generation circuits 19a, 19b and 19c are shifted by 1/3 each, the three light sources provided in the backlight module 5 are only driven by driving the fluorescent tubes in accordance with the sent dimming signal. Turns on and off three phases sequentially.
  • the numeral 1/3 means that three-phase control is performed as the light source in the present embodiment, and when the light source is controlled with N phases, it is shifted by 1 / N.
  • the pulse rise timing is calculated using the pulse interval and the duty ratio as parameters after receiving the vertical synchronization signal, and the trigger command position of the first pulse rise is determined.
  • the first pulse generated by each of the dimming signal generation circuits 19a, 19b, and 19c is shifted so that the phase of the pulse train of the dimming signal generated by each dimming signal generation circuit is shifted by 1/3 period. Calculate the startup timing.
  • the phases of the pulse trains generated in the respective light control signal generation circuits are shifted, and as the respective pulse trains shift to the moving image mode, the fluorescent tube lighting period and the light off period in the light control signal are substantially Since the intermittent lighting becomes more prominent sequentially by being divided into two, it becomes an image display which reduces the image outline blurring of a moving image.
  • the width of the pulse is determined based on the duty ratio sent from the screen brightness adjustment signal receiving unit 17, and the pulse interval sent by the pulse interval calculation unit 13 is The pulse interval is determined, and three pulses are generated according to the trigger sent by the pulse generation timing control unit 15. Thus, the dimming signal is sent to the backlight module 5.
  • FIG. 8A shows the luminance (solid line) emitted by the light source within the unit vertical synchronization period in the moving image mode obtainable from the present embodiment and the square wave (dashed line) of the dimming pulse.
  • FIG. 8 (b) shows the luminance (solid line) emitted by the light source within the unit vertical synchronization period in the moving image mode obtainable from the conventional example and the square wave (broken line) of the dimming pulse.
  • FIG. 8A shows the luminance (solid line) emitted by the light source within the unit vertical synchronization period in the moving image mode obtainable from the present embodiment and the square wave (dashed line) of the dimming pulse.
  • FIG. 8 (b) shows the luminance (solid line) emitted by the light source within the unit vertical synchronization period in the moving image mode obtainable from the conventional example and the square wave (broken line) of the dimming pulse.
  • FIG. 8C shows the luminance (solid line) emitted by the light source in the still image mode within the unit vertical synchronization period and the square wave (dashed line) of the dimming pulse which can be obtained from this embodiment and the conventional example.
  • the luminance generates a non-linear curved wave according to the number of pulses. Since this and the number of falling of the non-linear curvilinear wave of luminance in the still image mode are the same, steady-state luminance change and chromaticity change are suppressed.
  • the flushing phenomenon occurs.
  • the mode switching is performed by gradually adjusting the transition between the moving image mode of FIG. 8A and the still image mode of FIG. 8C, the flushing phenomenon does not occur.
  • FIGS. 9 and 10 show the measurement results of luminance and chromaticity in the above-described moving image mode and still image mode.
  • FIG. 9 shows the luminance and chromaticity of the moving image mode and the still image mode according to the present embodiment
  • FIG. 9A is obtained through the dimming rate of the dimming pulse and the liquid crystal screen in the unit vertical synchronization period.
  • 9B shows only the chromaticity information obtained by removing the lightness component Y of the xy Y color system of the CIE color system from the color space in the moving image mode and the still image mode. It is shown.
  • the minimum pulse interval in the pulse train in FIG. 9 is set to 0.5 msec.
  • the minimum pulse interval in the pulse train is set to 0.05 msec.
  • FIG.9 (b) and FIG.10 (b) are compared, the difference of the graph of FIG.9 (b) with the graph of each chromaticity of moving image mode and still image mode is narrower. That is, according to this embodiment, it is shown that the change in chromaticity is suppressed in the moving image mode and the still image mode.
  • the video discrimination circuit 2 determines whether the video is a video that is hard to sense flicker or a video that is prone to flicker, and sends out a video discrimination signal of a moving image or a still image.
  • the pulse interval in the pulse train is narrowed to make the pulse train virtually into one pulse.
  • the pulse interval in the light control signal is made wide to evenly take the light off period of the fluorescent tube in the light control signal.
  • the lighting period and the extinguishing period of the fluorescent tube are divided into approximately two in the dimming signal when transitioning to the moving image mode, blurring of the image outline of the moving image is reduced, and the dimming signal is transitioned to the still image mode. Does not feel flicker on the liquid crystal screen because it has the same phase as the pulse train beyond the critical fusion frequency. Then, in the switching from the moving image mode to the still image mode, and also in the reverse switching, the brightness change is suppressed to less than ⁇ S in Weber's law by gradually adjusting the pulse interval. As a result, the viewer does not feel a momentary change in luminance, nor does it feel any steady change in chromaticity or change in luminance before and after switching.
  • one inverter IC is made to correspond to a plurality of CCFL tubes and the light source is controlled in three phases to efficiently match intermittent lighting to the writing response of the liquid crystal Crowded. While simplifying the control of the backlight, the response to the image outline blurring of the moving image is efficiently improved.
  • the configuration of the backlight control becomes simpler.
  • the present invention is not limited to the above embodiment, and can be modified as follows.
  • the light source is one
  • the inverter IC is one
  • the dimming pulse generation circuit is one as in a notebook personal computer
  • the intermittent lighting is controlled sequentially by the pulse generation timing control unit 15.
  • the phases of the respective light adjustment signals may be shifted in the back light module and the intermittent lighting may be sequentially performed.
  • the dimming signal 1 is sent to the backlight module, and a pulse whose phase is shifted is generated based on this signal.
  • the phase of the pulse may be shifted before the rewriting of the pixel signal according to the response speed of the liquid crystal, or the phase of the pulse may be shifted after the rewriting.
  • the video discrimination circuit 2 performs video discrimination based on the video signal sent in real time, and transmits the video discrimination signal to the dimming signal generation circuit 3, but this is replaced by the video prediction circuit. May be Based on the video signal, the video prediction circuit predicts whether the video image will be a video that is not likely to sense flicker or is likely to be a flicker and the video prediction signal is sent to the dimming signal generation circuit 3. Therefore, it is possible to realize the lighting of the back light with high responsiveness to moving pictures and still pictures.
  • a CCFL tube is used for the backlight module, but EL (electroluminescence) coated with a fluorescent paint may be used. Steady-state chromaticity changes can be suppressed.

Abstract

Selon l'invention, au moment de l'affichage d'une image vidéo (image en mouvement) dont il est difficile de détecter le scintillement, et au moment de l'affichage d'une image vidéo (image fixe) dont il est facile de détecter le scintillement, au lieu de changer le nombre d'une pluralité d'impulsions de lumière modulée à générées pendant la période de synchronisation verticale unitaire, l'unité d'affichage d'image à cristaux liquides commande des impulsions de lumière modulée pour un rétroéclairage par changement de phases d'impulsions pendant la période de synchronisation verticale unitaire. Au moment de l'affichage de l'image en mouvement, les intervalles d'impulsion sont réduits de façon à combiner une pluralité d'impulsions en une pseudo-impulsion unique. Au moment de l'affichage de l'image fixe, les intervalles d'impulsion sont égalisés, ce qui génère, en un pseudo-mode, des impulsions de lumière modulée de fréquence différente pour l'affichage de l'image en mouvement et de l'image fixe. En réalité, toutes les fréquences des impulsions de lumière modulée restent inchangées, et, par conséquent, les variations de chrominance et de luminance des images au moment de l'affichage de l'image en mouvement et de l'image fixe peuvent être restreintes ; de plus, le flou de l'image en mouvement et le scintillement de l'image fixe peuvent également être restreints.
PCT/JP2009/001658 2008-04-11 2009-04-09 Unité d'affichage d'image à cristaux liquides WO2009125600A1 (fr)

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WO2012165304A1 (fr) * 2011-05-27 2012-12-06 シャープ株式会社 Dispositif d'affichage à cristaux liquides et procédé d'attaque de dispositif d'affichage à cristaux liquides
JP2013218190A (ja) * 2012-04-11 2013-10-24 Sharp Corp 液晶表示装置
JP2013222081A (ja) * 2012-04-17 2013-10-28 Sharp Corp 液晶表示装置
WO2015136569A1 (fr) * 2014-03-11 2015-09-17 パナソニック液晶ディスプレイ株式会社 Dispositif d'affichage et son procédé de commande
WO2015136571A1 (fr) * 2014-03-11 2015-09-17 パナソニック液晶ディスプレイ株式会社 Dispositif d'affichage et son procédé d'entrainement
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JP2007256678A (ja) * 2006-03-23 2007-10-04 Sharp Corp 液晶表示装置及びその駆動方法、並びに液晶表示装置に用いられるバックライト装置及びその駆動方法
JP2008052131A (ja) * 2006-08-25 2008-03-06 Taiyo Yuden Co Ltd 液晶バックライト駆動装置

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JP2007256678A (ja) * 2006-03-23 2007-10-04 Sharp Corp 液晶表示装置及びその駆動方法、並びに液晶表示装置に用いられるバックライト装置及びその駆動方法
JP2008052131A (ja) * 2006-08-25 2008-03-06 Taiyo Yuden Co Ltd 液晶バックライト駆動装置

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US9142188B2 (en) 2010-03-25 2015-09-22 Nokia Technologies Oy Methods and apparatus for reducing flickering and motion blur in a display device
US10991338B2 (en) 2010-03-25 2021-04-27 Nokia Technologies Oy Apparatus, display module and method for adaptive blank frame insertion
WO2011135389A1 (fr) * 2010-04-27 2011-11-03 Thomson Licensing Procédé et appareil pour occultation adaptative de rétro-éclairage principal dans des affichages à cristaux liquides
CN102859573A (zh) * 2010-04-27 2013-01-02 汤姆森特许公司 液晶显示器中自适应主背光消隐的方法和设备
WO2012165304A1 (fr) * 2011-05-27 2012-12-06 シャープ株式会社 Dispositif d'affichage à cristaux liquides et procédé d'attaque de dispositif d'affichage à cristaux liquides
JP2013218190A (ja) * 2012-04-11 2013-10-24 Sharp Corp 液晶表示装置
JP2013222081A (ja) * 2012-04-17 2013-10-28 Sharp Corp 液晶表示装置
JP2015166755A (ja) * 2014-03-03 2015-09-24 株式会社メガチップス デューティ比制御回路およびバックライト調整回路
WO2015136569A1 (fr) * 2014-03-11 2015-09-17 パナソニック液晶ディスプレイ株式会社 Dispositif d'affichage et son procédé de commande
WO2015136571A1 (fr) * 2014-03-11 2015-09-17 パナソニック液晶ディスプレイ株式会社 Dispositif d'affichage et son procédé d'entrainement
US9972264B2 (en) 2014-03-11 2018-05-15 Panasonic Liquid Crystal Display Co., Ltd. Display device and driving method thereof
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