JP2002072988A - Image display device, light emitting body and its driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the degradation in the display quality that occurs in an image display device while displaying a high speed animation and to prevent the reduction in the service life of a light emitting body and display luminance. SOLUTION: When display elements having the same scanning timing are used as display element groups, the groups are divided into display element groups in the order of ealier scanning timing and so that at least one display element group belongs to a group. Then, an illuminating section illuminates the display elements with first luminance and second luminance that is darker than the first luminance alternately for every display element group with a period identical to one frame time of a screen and with varying timing for every display element group. Thus, illumination of each display element is changed from a normal turned on state to a reduced light state in the frame time unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device for displaying information by illuminating a display element, a luminous body, and a method of driving the luminous body.

[0002]

2. Description of the Related Art In an image display device such as a liquid crystal display device used as a display screen of a conventional notebook personal computer, word processor, or the like, the response time of the liquid crystal is slow. There is a decrease in display quality such as blurring.

Therefore, for example, Japanese Patent Application Laid-Open Nos. 1-082019, 11-202285, 11-202
In Japanese Patent Application Publication No. 202286, the illumination unit has a plurality of light emitting regions in the scanning direction, and synchronizes the plurality of light emitting regions with a vertical synchronization signal of the image display device. That is, it is described that good display quality can be obtained by forming each light-emitting body to be turned on immediately after scanning of the display unit and turned off after a predetermined time.

In the above-mentioned prior art, when sequentially scanning and lighting the illuminating section of the image display device, each light emitting element is always turned off.

[0005]

As described above, in the above-mentioned prior art, when the illumination section of the image display device is sequentially scanned and lit, the light emitting elements are always turned off. However, this light-off operation has the following problems. (1) The light emitting body is repeatedly turned on and off at the frame frequency, thereby damaging the light emitting body and, as a result, the durable life of the light emitting body is reduced. (2) In addition, since there is a light-off period, display luminance is significantly reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to obtain a good display quality even at a high-speed moving image, and to reduce the durable life of the luminous body and the display luminance. It is an object of the present invention to provide an image display device, a luminous body, and a method for driving the luminous body, which can be prevented from occurring.

[0007]

In order to solve the above-mentioned problems, an image display apparatus according to the present invention comprises a plurality of display elements constituting one screen, which modulate light according to image data applied while being scanned. And, in an image display device provided with an illuminating unit that illuminates the display element, when the display elements having the same scanning timing are used as a display element group, the display element group is arranged in the order of earlier scanning timing, and one The group is divided into display element groups so that at least one display element group belongs to the group. The illumination unit is provided for each of the display element groups at the same period as one vertical period of a screen, and With different change timing for each
The display device is characterized in that the display element is illuminated while changing between the luminance and a second luminance which is darker and brighter than when the light is turned off.

With the above arrangement, the illuminating unit changes between the first luminance and the second luminance which is lower than the first luminance in the same cycle as one vertical period (vertical synchronization period) of the screen for each display element group. . The change timing differs for each display element group. As a result, in each display element group, for a time equal to one vertical period, for example,
The second lighting state of the second luminance, for example, a state of dimming from normal, is switched to a first lighting state of the first luminance, which is higher than that, for example, a normal lighting state. As a result, the illumination of each display element changes between a normal lighting state and a dimmed state in units of vertical periods.

Therefore, instead of turning on and off at the frame frequency in the luminous body, the lighting state at the time of display of the corresponding display element and the light emitting state which is weaker than the light emitting state but not at all are not turned off. By changing to the light state, the luminance changes between the first luminance and the second luminance, which is weaker light emission, so that damage to the luminous body can be effectively prevented. It can extend the durable life of the body.

[0010] Further, since there is no light-off period, the display luminance is not significantly reduced.

[0011] Further, while the light is lit at the dark second luminance,
During the response in the display element, that is, the image display while the light transmission state is changing to the state corresponding to the image data is inconspicuous, so that even a high-speed moving image can obscure a blurry image such as a trailing image. it can.

[0012] Therefore, good display quality can be obtained even in high-speed moving images, and a reduction in the durable life of the luminous body and a reduction in display luminance can be effectively prevented.

Here, for example, the illuminating section has a plurality of illuminating elements for illuminating the display elements in a shared manner, and each of the illuminating elements illuminates a plurality of display elements having the same or different scanning timing. Can be configured.
Further, for example, the configuration may be such that the luminance of the illumination unit is changed while synchronizing the scanning of the display element with each screen. Further, for example, the illumination unit has a plurality of light-emitting regions (illumination elements) in a scanning direction, and the plurality of light-emitting regions are sequentially scanned and dimmed in synchronization with a vertical synchronization signal of the image display device. can do.

Further, the image display device according to the present invention includes, for example, a plurality of signal lines and a plurality of scanning lines arranged crossing each other, a signal line driver circuit for writing display data to each signal line, each scanning line, A scanning line driver circuit for scanning a line can be provided.

Further, in the image display device of the present invention, in addition to the above configuration, in the illumination section, in each of the display element groups, at least a display element group A having the earliest scanning timing is scanned. From the time point, 1/1 of one vertical period
Until the time when 0 elapses, the second luminance is set.

With the above arrangement, the illuminating section is configured such that, in each of the display element groups, at least from the time when the display element group A having the earliest scanning time is scanned.
The second luminance is set until the time when 1/10 of one vertical period elapses. In this manner, the second luminance is ensured from the time when the display element group A is scanned to the time when 1/10 of one vertical period elapses, and the second luminance remains at the other time for the rest of the time. Eventually, the luminance changes to the first luminance, or the luminance immediately changes to the first luminance and changes to the second luminance again. Here, as a result of the experiment, it has been clarified that, in any of these cases, there is no tailing in the high-speed moving image, and a decrease in the overall luminance is effectively prevented. Therefore, if only the first 1/10 of the one vertical period is set to the second luminance, it is possible to set the luminance widely according to other conditions while keeping the display quality high. Therefore, in addition to the effect of the above configuration, the degree of freedom in designing the image display device can be increased.

Further, in the image display device of the present invention, in addition to the above configuration, the illuminating unit scans at least the display element group A having the earliest scanning time in each of the display element groups. The second luminance is set from the time when 1/10 of one vertical period elapses to the time when 1/10 of one vertical period further elapses.

With the above arrangement, the illuminating unit is configured such that, in each of the display element groups, at least one tenth of one vertical period has elapsed since the display element group A having the earliest scanning time has been scanned. To the time point when 1/10 of one vertical period further elapses, the second luminance is set. With this configuration, the second luminance is reliably obtained from the time when 1/10 of one vertical period has elapsed from the time when the display element group A is scanned to the time when 1/10 of one vertical period has further elapsed, At other times, for example, the first 1 /
Regarding the period up to 10, the second luminance has already been reached from the time when the display element group A was scanned, or the first luminance at the time when the display element group A was scanned, and then one of the one vertical period At the time when / 10 has elapsed, the second luminance is changed. Similarly, the luminance is the first luminance or the second luminance after a lapse of 2/10. Here, as a result of the experiment, it has been clarified that, in any of these cases, there is no tailing in the high-speed moving image, and a decrease in the overall luminance is effectively prevented. Therefore, as long as the second luminance is considered during the first 1/10 to 2/10 of one vertical period, the luminance can be set widely according to other conditions while maintaining high display quality. It becomes possible. Therefore, in addition to the effect of the above configuration, the degree of freedom in designing the image display device can be increased.

Further, in the image display device of the present invention, in addition to the above configuration, the illuminating unit may be configured such that, in each of the display element groups, at least a point in time when the display element group A having the earliest scanning time is scanned. , The display element of the display element group A can be configured to illuminate the display element with the second luminance at most thereafter until the display element of the display element group A completes the response.

As a result, after the display elements belonging to the display element group are scanned, the display elements are not changed until the display elements complete the response (change of the light transmission state or reflection state to a state corresponding to the image data). During the specified period, which maximizes the period,
At least the illumination for the display element group has the second luminance. Therefore, during the predetermined period included in the period until the response in the display element is completed, the display device is illuminated with the dark second brightness, so that the display in the middle of the response can be made inconspicuous. It is possible to more effectively prevent a blurred image having a tail from being conspicuous. Therefore, in addition to the effects of the above-described configuration, it is possible to obtain a better display quality in a high-speed moving image, while effectively preventing a reduction in the durability life of the light emitter and a reduction in display luminance.

Further, for example, after the change to the state corresponding to the image data is substantially completed, the light can be turned on at the first luminance higher than the second luminance immediately or after a while. . Further, for example, it is possible to configure so that the display element shifts to the second luminance at the latest until the display element is scanned again next time.

Further, the luminous body of the present invention has a period in which light is emitted at a first luminance level and a period in which light is emitted at a second luminance level within a vertical period, wherein the first luminance level and the second luminance level are different from each other. Are different from each other, and both are brighter than when turned off.

Further, the luminous body of the present invention is characterized in that it is a cold cathode tube in addition to the above configuration.

Further, the light-emitting body of the present invention is characterized in that it is a light-emitting diode element in addition to the above structure.

Further, the luminous body of the present invention is characterized in that it is an electroluminescent element in addition to the above configuration.

The luminous body of the present invention is characterized in that it is a hot cathode tube in addition to the above constitution.

Further, the luminous body of the present invention is characterized in that it is a mercury lamp in addition to the above configuration.

The luminous body of the present invention is characterized in that it is a halogen lamp in addition to the above configuration.

Further, the luminous body of the present invention is characterized in that it is a laser in addition to the above configuration.

Further, according to the driving method of the light emitting body of the present invention, the first driving signal and the second driving signal are input to the light emitting body at different timings within the vertical period, so that the first driving signal is applied to the light emitting body. It is characterized in that the luminance of the light emitter is different from the luminance when the second drive signal is input to the light emitter, and both are brighter than when the light is turned off.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 1, a liquid crystal display device 1 as an image display device according to the present embodiment has, for example, 64
It is an active matrix type having a TFT (thin film transistor) of 0 × 480 dots. In a liquid crystal panel (display unit) 5 as an image panel, a liquid crystal (not shown) as a plurality of display elements constituting one screen, which modulates a light transmission state of the liquid crystal according to image data applied while being scanned. A display element (pixel) is provided, and for example, a twisted nematic liquid crystal is sealed in the liquid crystal display element. The liquid crystal panel 5 includes a gate driver 3 for driving a scanning line in the liquid crystal panel 5 and a source driver 4 for driving a signal line. The liquid crystal display device 1 includes:
A liquid crystal panel control circuit 2 to which a video signal is input is provided. A video signal is transmitted from the liquid crystal panel control circuit 2 through the gate driver 3 and the source driver 4 to the liquid crystal panel 5.
And a video signal is applied to the liquid crystal display element. That is, the signal voltage of the video signal is applied to the corresponding signal line at the timing when the scanning pulse is applied to the corresponding scanning line.

An inverter control circuit 6 as a lighting control circuit is provided, and is connected so as to receive a vertical synchronization signal of the present liquid crystal display device 1 from the liquid crystal panel control circuit 2. Further, a plurality of, for example, five inverters 7 for lighting driving are provided. The inverters 7 receive drive signals output from the inverter control circuit 6 and apply predetermined high-frequency, high-voltage waveform signals to a plurality of, here five, cold-cathode tubes (illumination elements) 8 which are luminous bodies. It is designed to be applied. From the cold cathode tube 8 at the scanning start position to 1
The number 5 is assigned, and the inverters connected to them are referred to as inverters (1) to (5), respectively. The inverter control circuit 6 outputs an inverter input signal to each of the five inverters 7, and each of the five inverters 7 drives each of the five cold cathode tubes 8 to emit light in accordance with the inverter input signal. Has become. The inverter control circuit 6, the inverters 7, and the cold cathode tubes 8 constitute a lighting unit.

The cold cathode tubes 8 are backlights for illuminating the liquid crystal display element of the liquid crystal panel 5 from behind as a light emitting area, and the luminous intensity of the cold cathode tubes 8 becomes the luminance of the illumination section.
Five cold cathode tubes 8 and five inverters 7 are provided. The cold cathode tubes 8 are arranged side by side in the signal line direction (vertical scanning direction) so that the longitudinal direction is parallel to the scanning lines, and all five tubes are equidistant from each other.

As shown in FIG. 4, the liquid crystal display device 1 has a configuration in which a liquid crystal panel 5 and a backlight unit 10 are bonded to each other. The backlight unit 10 is a direct type illumination device, in which a diffusion plate 11 is provided on a surface facing the liquid crystal panel 5 and a reflection plate 12 is provided on the opposite surface, and cold cathode tubes 8 are arranged between them. It is the configuration that was done. In the figure, the liquid crystal panel control circuit 2, gate driver 3, source driver 4, inverter control circuit 6, and inverter 7 are not shown.

As described above, five cold cathode tubes 8 are provided. Therefore, in the case of 640 × 480 dots, one cold cathode tube 8 corresponds to 96 scanning lines. That is,
The first cold cathode tube 8 illuminates the pixels for the first to 96th scanning lines, and the second cold cathode tube 8 illuminates the pixels for the 97th to 192th scanning lines. The same applies hereinafter. That is, assuming that the number of the cold cathode tubes 8 is M and the number of scanning lines, that is, the number of pixels in the scanning direction is N, the n-th cold cathode tube 8 is {(n−1) · (N / M) +1}. This one-$ n
(N / M) illuminate the pixels for the scan line.
Here, the number of the cold cathode tubes 8 is not particularly limited as long as the number of the cold cathode tubes 8 can be effectively reduced, as described later, such as a reduction in display quality such as a trailing phenomenon in a high-speed moving image.

Here, the liquid crystal display elements having the same scanning timing are referred to as a display element group. That is, in this example, one display element group includes 640 liquid crystal display elements corresponding to one scanning line. This display element group is arranged in the order of earlier scanning time.
The display elements are grouped into display element groups such that at least one display element group belongs to one group. That is, in this example, one display element group is configured for every 640 × 96 liquid crystal display elements corresponding to the adjacent 96 scanning lines in the order of earlier scanning timing.

FIG. 2 shows waveforms of the vertical synchronizing signal received by the inverter control circuit 6 and the inverter input signals (1) to (5) as drive signals output to the inverter 7. The inverter input signals (1) to (5) are signals input to the inverters (1) to (5) in FIG. 1, respectively. FIG. 3 shows a light emission waveform of any one of the cold cathode tubes 8 and a corresponding inverter input signal input to the inverter 7 for driving the cold cathode tube 8. In this way, each light emitter performs sequential scan lighting (blinking) and scan dimming in synchronization with the vertical synchronization signal by the inverter input waveform as shown in FIG. Performing sequential scan dimming in synchronization with the vertical synchronization signal means that as the display elements to be scanned change one after another, the light emitter selected corresponding to the display element being scanned also changes,
With respect to the selected illuminant, the light is dimmed for at least a part of the selection period, and when the next illuminant is selected after the selection period, the illuminant in the non-selected state is By repeating the operation of returning to the original lighting state in at least a part of the non-selection period, the light-emitting bodies to be dimmed are sequentially changed (scanned) in synchronization with the vertical synchronization signal. That's what it means.

The inverter control circuit 6 has, for example, a counter and a shift register (not shown). The horizontal synchronizing signal is input to the counter, and the vertical synchronizing signal is input to the shift register. The pulse width of each inverter input signal, that is, the duty ratio is determined by counting (dividing) the horizontal synchronizing signal by the counter. The shift register outputs the inverter input signal (1) to the corresponding inverter (1) of the inverter 7 in synchronization with the vertical synchronization signal (rising timing). Next, in order to sequentially shift the dimming start times of the cold cathode tubes 8 as described later, the shift register sequentially shifts the timing of a predetermined inverter control clock (not shown) for determining the phase shift amount of the inverter input signal. The inverter input signals (2) to (5) are
Output to Since the five cold-cathode tubes 8 sequentially enter the dimming period at one frame time, the phase shift amount is given by the frame time / the number of cold-cathode tubes.

In the present embodiment, with respect to the inverter input signals (1) to (5), the inverter input signals of the adjacent inverters are overlapped with a bright lighting period, that is, a high voltage period. However, the present invention is not limited to this, and a high voltage period of the next inverter input signal may be started at a time when a certain inverter input signal starts dimming, that is, at a time when the voltage becomes low. Further, a short period after a certain inverter input signal enters the dimming period, a high voltage period of the next inverter input signal may be started. The pulse width of each inverter input signal can be arbitrarily set at the time of manufacture or use by determining how many horizontal synchronization signals are counted as described above. Further, the amount of phase shift between the inverter input signals can be arbitrarily set at the time of manufacture or use by adjusting the inverter control clock.

The time at the high voltage level is denoted by ta, and the time at the low voltage level is denoted by tb. Assuming that one frame time is f, ta + tb = f. The drive signal output from the inverter control circuit 6 to each of the inverters 7 has a low voltage level (3 V) at the same time that the area illuminated by the cold cathode tubes 8 is scanned.
It is set to become. Then, here, after a lapse of tb (for example, 1/2 frame time) from the low voltage level state, the voltage becomes the high voltage level (9 V), and it becomes ta (for example, 1/2 frame time (f-tb)). )
Only to last. As shown in FIG. 3, when the inverter input signal goes to a high voltage level in response to the drive signal, the cold cathode fluorescent lamp 8 ends the dimming period and lights up with a normal brightness (first brightness). I will be. On the other hand, when the inverter input signal becomes a low voltage level, a dimming period is started, and the light is dimmed more than usual, and is lit at a predetermined luminance (second luminance) that is darker and brighter than the unlit state. The time from the dimming start timing to the dimming end timing is a dimming period.

With such a driving system, the five cold cathode tubes 8 are scanned while being sequentially dimmed. That is, as shown in FIG. 2, during one frame time, the inverter input signal (1) becomes a low voltage level at the same timing as the vertical synchronizing signal, and the first cold cathode tube 8, that is, the cold cathode tube (1) is turned on. Enters the dimming period. After a lapse of a predetermined time, that is, a time (td) corresponding to the above-described phase shift amount between the inverter input signals (1) and (2), the inverter input signal (2) becomes the low voltage level and becomes the second voltage. Of the cold cathode tube 8, that is, the cold cathode tube (2) enters the dimming period. The same applies hereinafter.

Therefore, in this example, when each pixel is scanned, the cold-cathode tube illuminating the pixel enters a dimming state, and thereafter, at least one frame time elapses from the start of the dimming. By this time (in this example, at the time when tb (for example, 1/2 frame time) elapses as described above), the state shifts to the normal lighting state.

Observation of a high-speed moving image with a liquid crystal display device using the cold cathode tubes 8 revealed that a much clearer image was obtained than with a conventional liquid crystal display device.

As described above, in the present embodiment, the cold cathode tube 8 as a plurality of light emitting areas is provided in the scanning direction, and the plurality of light emitting areas are synchronized with the vertical synchronizing signal of the liquid crystal display device by a predetermined number. Scanning is sequentially turned on (blinks) while the brightness of the scan is gradually reduced at a predetermined timing.
The phase of the light emission timing of each cold cathode tube 8 is shifted in accordance with the scanning timing of the display element group illuminated by each cold cathode tube 8. This makes it possible to obtain a liquid crystal display device having good display quality while suppressing a reduction in the durability life of the luminous body and a significant decrease in display luminance.

Here, for example, the ratio of the time of each luminance (duty ratio) can be configured to be different for each group of the display elements or can be configured to be equal. In addition, for example, in the same order as the order in which the display elements are scanned, for a predetermined period, the change timing of each illumination element is shifted for each group of the display elements such that the change timing is delayed or accelerated. It can be. Further, the amount of the timing shift can be the same or different for all display element groups.

In this example, the dimming is performed continuously from the start time to the end time.
Thereafter, until one frame time elapses, the dimming period and the non-dimming period are set to be once. Here, for example, it is also possible to configure so that the luminance changes once or more from the time of the luminance change to the lapse of one frame time thereafter. For example, from the point in time when the second luminance (dimming state) is changed to one frame time thereafter,
The brightness changes only once to the first brightness (normal lighting state), or once changes to the first brightness and then to the second brightness, or changes once to the first brightness and then to the second brightness , And the first luminance can be obtained again.

Next, the luminance level at the time of dimming was changed.
The luminance level at the time of dimming can be controlled by adjusting the low voltage level of the drive signal output from the inverter control circuit 6 to the inverter 7. As a result, the brightness level at the time of dimming is
When the luminance was set to 9/10 or less of the luminance at the time of lighting at 100%, deterioration in display quality such as tailing was suppressed more effectively even in a high-speed moving image, and better display quality could be obtained. Further, when the luminance level at the time of dimming is set to 1/10 or more of the luminance at the time of 100% lighting, the decrease in the display luminance can be suppressed more effectively, and the durability life of the cold cathode fluorescent lamp 8 decreases. Speed has been reduced.

Next, the degree of improvement in display quality by the setting position of the dimming period was examined. FIG. 5 shows the results. In the drawing, the dimming period start timing and the dimming period end timing are expressed in frame time (f) units with the time when the scanning of each light emitting region is started as a reference (time zero). In FIG. 5, if the dim period start timing is greater than (is later than) the dim period end timing, the dim period ends at the corresponding timing of the next frame (dimming period end timing). Is shown. The point in time when the scanning of each light emitting area is started is, in other words, the point in time when the scanning of the display element group (A) with the earliest scanning time is started in the display element group corresponding to each light emitting area. That's what it means. Then, as a result of comparison with the conventional configuration in which the light-emitting body is always turned on without scanning the light-emitting body, as a display quality, “◎” in the figure indicates that a large improvement in the display quality has been confirmed as compared with the related art.
“○” indicates that the display quality was improved compared to the conventional one, “△” indicates that the display quality was slightly improved compared to the conventional one, and “×” indicates that the display quality was improved. Indicates that you cannot. Classification was performed in this way, and an experiment was performed on 10 test subjects at each timing combination to evaluate the results. High-speed moving images were used as evaluation images. As a high-speed video, here is a video of a sports program on TV (a video in which the movement of athletes such as tennis, volleyball, baseball and baseball and the ball is intense)
Also, using a video of characters scrolling with names of staff and performers displayed at the end of a television program, etc., evaluation was made based on whether or not display quality was improved without tailing or the like.

From the results shown in FIG. 5, it can be seen that the display quality changes depending on how the dimming period and the dimming start timing and end timing are set. Furthermore, from this result, it can be seen that particularly when the period in which the liquid crystal of the pixel in the light emitting region responds to the signal voltage substantially coincides with the dimming period, a particularly large improvement in display quality can be seen.

From the above detailed experiments, it has been found that the following conditions are desirable in order to obtain a particularly great effect. That is, (1) the luminance in the dimmed state is 1 / the luminance at 100% lighting.
10 or more and 9/10 or less. (2) The dimming period is 1/10 or more of one frame time 9 /
10 or less. (3) On the basis of the time when the scanning of the display section of the light emitting area is performed, the light emitting area is in a dimmed state at least for 1/10 of one frame time immediately after the reference time. More preferably, the light-emitting area is in a dimmed state at least for at least 5/10 of one frame time from immediately after the reference time with respect to the time when the scanning of the display section of the light-emitting area is performed. . (4) More preferably, after the scanning of the display unit corresponding to the light emitting area is performed, at least the light emitting area is in a dimming period until the liquid crystal of the pixel substantially completes the response. . It is. Under the conditions described above, there is no reduction in the durability life of the luminous body, a remarkable decrease in display luminance can be suppressed more remarkably, and more excellent display quality can be obtained. The above driving method shows a great effect particularly in high-speed moving image display. In other words, by having the function of adjusting the brightness and timing described above in response to the high speed of the moving image, high-speed moving image display can be achieved while suppressing a reduction in the durable life of the light emitter and a decrease in the display luminance more remarkably. Thus, a liquid crystal display device having good display quality can be obtained.

Further, the end timing of the dimming period is (1/1)
0) · f, (0/10) · f to (1/1)
0) · f is always dimmed. When the dimming period end timing is (2/10) · f, (1/1)
The light is always dimmed from 0) .f to (2/10) .f. As can be seen from the figure, when the dimming period end timing is (1/10) · f or (2/10) · f, the display quality is improved regardless of the dimming period start timing. are doing. Therefore, it is possible to reduce restrictions in determining the start timing of the dimming period and increase the degree of freedom in designing the liquid crystal display device.

The start timing of the dimming period is (0/1)
0) · f, (0/10) · f to (1/1)
0) · f is always dimmed. If the dimming period start timing is (1/10) · f, (0/1
From (0) · f to (1/10) · f, it is always a normal lighting state (non-dimming state), and from (1/10) · f to (2/10) · f. It is fading. As can be seen from the figure, when the dimming period start timing is (0/10) .f or (1/10) .f, the display quality is improved regardless of the dimming period end timing. are doing. Therefore, it is possible to reduce restrictions in determining the end timing of the dimming period and increase the degree of freedom in designing the liquid crystal display device.

In the above-mentioned study, a high-speed moving image is selected as the evaluation image. However, moving images and still images are mixed in the actually broadcasted image and the like. In view of this, the liquid crystal display device may be provided with a mechanism for detecting the high speed of a moving image of a video, so that the dimming period and the luminance of the illumination unit are automatically adjusted. More specifically, the higher the speed of the moving image, the lower the brightness in the dimmed state and the longer the dimming period. On the other hand, when there is only a still image, the dimming state is not provided. As a result, it is possible to more efficiently improve the display quality and reduce the durable life of the cold-cathode tube 8 (light emitter). That is, in the case of a still image,
It is possible not to provide a dimming state. By doing so, not only the light is not turned off but also the light is not dimmed, so that the reduction in the durability life of the cold cathode tube 8 can be further suppressed. In addition to providing the image detection mechanism, a similar effect can be obtained even if the user can arbitrarily adjust the dimming period and the luminance of the illumination unit from outside.

The present invention is not limited to a liquid crystal display device, but includes a display element (such as a shutter or a reflector) having a shutter function for controlling (modulating) light transmittance or reflectance, and an illumination unit. (Light source such as a cold cathode tube) can be widely applied to a configuration in which an image is displayed. Examples of the display element having such a shutter function include the following. (1) Birefringence is generated by an external field (liquid crystal generates birefringence in an electric field). For example, magneto-optical element (by magnetic field), Pockels cell (Pockels shutter by electric field), car cell (Car shutter by electric field)
Such. (2) The reflectance and color change depending on the external field. For example, an electrochromic element (for example, a color (reflection color) changes by an oxidation-reduction reaction by an electric current), a photochromic element (the transmittance is changed by a laser beam or the like), and the like. (3) Mechanical shutter or reflector. For example, a micro machine (a fine mechanical element is provided for each pixel; for example, a mechanical fine shutter).

Although the present embodiment has been described on the assumption that the video signal is of the interlace drive system, the present invention is not limited to this. For example, the present invention can be realized even in the case of a video signal of a non-interlace drive system. In the case of the interlace driving method, one field corresponds to one vertical period, whereas in the case of the non-interlace driving method, one frame corresponds to one vertical period.

The image display apparatus according to the present invention scans a plurality of signal lines and a plurality of scanning lines, a signal line driver circuit for writing display data to each signal line, and each scanning line. In an image display device including a display unit provided with a scanning line driver circuit and an illumination unit that illuminates the display unit, the illumination unit has a plurality of light-emitting regions in a scanning direction, and the plurality of light-emitting regions The image display device may be configured so that the scan light is sequentially reduced in synchronization with the vertical synchronization signal of the image display device.

Further, the image display device according to the present invention may be configured such that the luminance in the dimmed state is 1/10 or more and 9/10 or less of the luminance in the 100% lighting state.

Further, in the image display device according to the present invention, in the above configuration, the dimming period is set to 1/10 of one frame time.
You may comprise so that it may be more than 9/10 or less.

Further, in the image display device according to the present invention, in the above-described configuration, at least 1/10 of one frame time from immediately after the reference time with respect to the time when the scanning of the display unit corresponding to the light emitting area is performed. During the period, the light emitting region may be configured to be in a dimmed state.

Further, in the image display device according to the present invention, in the above-described configuration, at least 5/10 of one frame time from immediately after the reference time based on the time when the scanning of the display section corresponding to the light emitting area is performed. During the period, the light emitting region may be configured to be in a dimmed state.

Further, in the image display device according to the present invention, in the above-described configuration, after the scanning of the display unit corresponding to the light-emitting area is performed, the display element such as the liquid crystal of the pixel generally completes the response. May be configured so that at least its light emitting region is in a dimmed state period. For example, the lighting unit has a plurality of lighting elements as light emitting areas, and in each lighting element, after scanning of a light emitting area, that is, a display element illuminated by the lighting element is scanned, response in the display element, that is, light transmission is performed. Until the change of the state or the reflection state to the state corresponding to the image data is substantially completed, at least the light emitting region may be configured to be lit in the dimmed state as the second luminance.

Further, the image display device according to the present invention may be configured such that the brightness in the dimmed state can be arbitrarily adjusted from the outside in the above configuration.

Further, in the image display device according to the present invention, in the above configuration, the brightness in the dimmed state may be changed according to the high speed of the moving image included in the video signal.

Further, the image display device according to the present invention may be arranged such that the length and timing of the dimming period can be arbitrarily adjusted from the outside in the above configuration.

Further, the image display device according to the present invention may be arranged such that the length and the timing of the dimming period are changed according to the high speed of the moving image included in the video signal.

It is preferable to use a cold cathode tube, a light emitting diode, an electroluminescence, a hot cathode tube, a mercury lamp, a halogen lamp, and a laser as the luminous body of the above embodiment.

[0068]

As described above, according to the image display device of the present invention, when the display elements having the same scanning timing are used as the display element group,
The display element group is divided into display element groups such that at least one display element group belongs to one group in the order of scanning time, and the illuminating unit includes a screen for each display element group. The display element is illuminated while changing between the first luminance and the second luminance which is darker than the first luminance and is brighter than when the light is turned off at the same cycle as one vertical period and at a different change timing for each display element group. is there.

The luminous body of the present invention has a period in which light is emitted at the first luminance level and a period in which light is emitted at the second luminance level within a vertical period. Are different from each other, and both are brighter than when turned off.

The luminous body of the present invention has a configuration in which a cold cathode tube is provided in addition to the above configuration. Further, the luminous body of the present invention has a structure in which the luminous body is a light emitting diode element in addition to the above structure. Further, the luminous body of the present invention has a structure which is an electroluminescent element in addition to the above structure. Further, the luminous body of the present invention has a configuration in which a hot cathode tube is provided in addition to the above configuration. Further, the luminous body of the present invention has a configuration that is a mercury lamp in addition to the above configuration. Further, the luminous body of the present invention has a configuration in which a halogen lamp is provided in addition to the above configuration. The luminous body of the present invention has a configuration in which a laser is used in addition to the above configuration.

Further, according to the driving method of the luminous body of the present invention, the first driving signal and the second driving signal are input to the luminous body at different timings within the vertical period, so that the first driving signal is supplied to the luminous body. The configuration is such that the luminance of the light emitter is different from the luminance when the second drive signal is input to the light emitter, and both are brighter than when the light is turned off.

As a result, the luminance changes between the first luminance and the second luminance, which is light emission weaker than the first luminance.
Damage to the luminous body can be effectively prevented, and there is no light-off period, and while the light is lit at the dark second luminance, the image of the display device during the response is inconspicuous. therefore,
It is possible to obtain a good display quality even in a high-speed moving image, and to effectively prevent a reduction in the durable life of the luminous body and a reduction in display luminance.

Further, in the image display device of the present invention, in addition to the above configuration, the illumination unit scans at least the display element group A having the earliest scanning time in each of the display element groups. From the time point, 1/1 of one vertical period
The configuration is such that the second luminance is set until the time when 0 elapses.

As a result, it is possible to set a wide range of luminance according to other conditions while maintaining high display quality. Therefore, in addition to the effect of the above configuration, there is an effect that the degree of freedom in designing the image display device can be increased.

Further, in the image display device of the present invention, in addition to the above configuration, the illuminating section scans at least the display element group A having the earliest scanning timing in each of the display element groups. From the time when 1/10 of one vertical period elapses to the time when 1/10 of one vertical period further elapses, the second luminance is set.

As a result, it is possible to set a wide range of luminance according to other conditions while maintaining high display quality. Therefore, in addition to the effect of the above configuration, there is an effect that the degree of freedom in designing the image display device can be increased.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of an image display device according to the present invention.

FIG. 2 is a timing chart showing a vertical synchronization signal and an inverter input signal.

FIG. 3 is a timing chart showing an inverter input signal and a light emission waveform of a cold cathode tube.

FIG. 4 is a cross-sectional view illustrating a configuration example of an image display device.

FIG. 5 is an explanatory diagram showing a relationship between dimming timing and display quality.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal display device (image display device) 2 Liquid crystal panel control circuit 3 Gate driver 4 Source driver 5 Liquid crystal panel (display part) 6 Inverter control circuit (illumination part) 7 Inverter (illumination part) 8 Cold cathode tube (illumination part) 10 Backlight part 11 Diffuser 12 Reflector

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09G 3/34 G09G 3/34 J (72) Inventor Makoto Shiomi 22-22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term in Sharp Corporation (reference) 2H091 FA41 FA42 FA44 FA45 FA46 GA11 GA13 LA18 2H093 NC16 NC34 NC42 NC56 ND05 ND07 NF05 5C006 AA01 AF44 BB11 BB29 EA01 FA29 FA33 GA03 5C080 AA10 BB05 DD05 DD06 DD29 EJ19 JJ12 FF19

Claims (12)

[Claims] 1. An image display device comprising: a plurality of display elements forming one screen for modulating light according to image data applied while being scanned; and an illumination unit for illuminating the display elements. When a display element having the same scanning timing is used as a display element group, the display element groups are grouped into display element groups in the order of early scanning timing, and at least one display element group belongs to one group. The illumination unit is provided on one of the screens for each of the display element groups.
The display device is illuminated in the same cycle as the vertical period and at a different change timing for each of the display device groups while changing between the first brightness and the second brightness which is darker and is brighter than when turned off. Image display device. 2. The lighting unit according to claim 1, wherein, in each of said display element groups, at least 1/1 of one vertical period from a point in time when the display element group A having the earliest scanning time is scanned.
2. The image display device according to claim 1, wherein the second luminance is set until the time when 0 elapses. 3. The lighting unit according to claim 1, wherein at least one-tenth of one vertical period has elapsed since the display element group A having the earliest scanning time in each of the display element groups has been scanned. 2. The image display device according to claim 1, wherein the second luminance is set until a time when 1/10 of one vertical period elapses. 4. A method according to claim 1, further comprising a period in which light is emitted at a first luminance level and a period in which light is emitted at a second luminance level within the vertical period.
A luminous body characterized in that the luminance level and the second luminance level are different from each other, and both are brighter than when turned off. 5. A cold-cathode tube according to claim 4.
A luminous body as described. 6. The luminous body according to claim 4, wherein the luminous body is a light emitting diode element. 7. The luminous body according to claim 4, wherein the luminous body is an electroluminescent element. 8. A hot-cathode tube according to claim 4.
A luminous body as described. 9. The luminous body according to claim 4, wherein the luminous body is a mercury lamp. 10. The luminous body according to claim 4, wherein the luminous body is a halogen lamp. 11. The luminous body according to claim 4, wherein the luminous body is a laser. 12. A first drive signal and a second drive signal are input to a light emitter at different timings within a vertical period, so that the first drive signal is input to the light emitter and the second drive signal emits light. A method for driving a light emitting body, characterized in that the luminance of the light emitting body is different from that when the light is input to the body, and both are brighter than when the light is turned off.