JP4566545B2 - Time-division gradation display drive, time-division gradation display - Google Patents

Description

  The present invention relates to a time-division gray scale display driving device for driving a display that displays gray scales in time division, and a time-division gray scale display provided with such a driving device, and more particularly, a current flowing through the display. The present invention relates to a time-division gray scale display driving device suitable for suppressing the maximum value and a time-division gray scale display equipped with such a driving device.

  In recent years, many flat-type displays are being used. Some of such flat displays control the light emission time in a time division manner to express gradation. For example, a PDP (plasma display panel) or an organic EL (electroluminescent) panel can be used. This is because the luminance cannot be controlled by an analog amount such as the intensity of an electron beam as in a CRT (cathode ray tube).

For example, Jun Koyama, “Acquisition of basic patent of circuit for high definition of organic EL panel”, NIKKEI ELECTRONICS, 2000.4.24. (No.768), pp. 163-170. The method is schematically described. Each lighting is set to a power ratio time of 2 in one frame, and a predetermined brightness is expressed by lighting a desired one of the lightings. An addressing period is provided prior to each lighting to turn on the desired one.
NIKKEI ELECTRONICS, 2000.4.24 (no.768), pp. 163-170

  In the time division gradation display as described above, it is a matter of course that a power supply unit corresponding to the case where the maximum current flows is necessary. The maximum current flows when each lighting period with a power ratio time of 2 is the same time zone for all pixels on the display. For example, a case where all the pixels have the same luminance is typical. This is because the maximum current is always required for each pixel in the lighting time out of the lighting time and the addressing time, and the time that can be lit is the same timing in each pixel.

  On the other hand, in order to eliminate the addressing time, it is also possible to adopt a method in which lighting is performed while performing addressing for each scanning line and the light is turned off corresponding to each lighting time of a power-of-two ratio time. In this case, since the lighting timing is different for each scanning line, the maximum current in the above sense does not occur. However, in each lighting period, for example, in the time zone of the power-of-two ratio time of the maximum, it is possible that all the scanning lines are turned on and the extinguishing of the first scanning line has not yet started. It can happen that the scanning lines are turned on simultaneously. Therefore, the maximum current corresponding to all the scanning lines and all the pixels is required at the time when the lighting can be performed for the maximum power-of-two ratio time. The power supply for preparing for such a large current is necessarily large.

  The present invention has been made in consideration of the above-described circumstances, and is a time-division gray scale display driving device for driving a display that displays gray scales in a time division manner and a time-division floor provided with such a driving device. An object of the present invention is to provide a time-division gray scale display driving device capable of suppressing the maximum value of the current flowing through the display, and a time-division gray scale display equipped with such a driving device. .

In order to solve the above-described problem, a time division gray scale display driving apparatus according to the present invention uses the first color pixels of the scanning line having the first, second, and third color pixels as the first color pixels. The first lighting scanning line driving unit that can be lit from top to bottom for each scanning line according to the first data from each data line, and the first lighting scanning line driving unit. A first extinction scanning line driving unit capable of extinguishing each first color pixel from top to bottom for each scanning line; and each second color pixel of the scanning line from each second data line. A second lighting scanning line driving unit that can be lit from top to bottom for each scanning line according to each second data, and each second color that is lit by the second lighting scanning line driving unit A second light-off scanning line driving unit capable of turning off the pixels from top to bottom for each scanning line; A third lighting scanning line driving section capable of lighting each third color pixel from top to bottom for each scanning line in accordance with each third data from each third data line; and the third lighting A third unlit scanning line driving unit capable of turning off each of the third color pixels turned on by the scanning line driving unit from top to bottom for each scanning line; and A first color signal driver for each color pixel via the first data line, and the second data for each second color pixel via the second data line. A second color signal driving unit for supplying the third color data, a third color signal driving unit for supplying the third data to the third color pixels via the third data lines, and the first color signal driving unit . The second scanning line drive unit turns on the scanning line at a speed at which the scanning line driving unit turns on the scanning line from top to bottom. The first, second, and third speeds so that the speed at which the light is lit from the bottom to the bottom and the speed at which the third lighting scanning line driver illuminates the scanning lines from top to bottom are different from each other. And a first variable clock frequency generation circuit for supplying a clock signal to each of the lit scanning line driving units .

In other words, each of the first, second, and third pixels constituting the scanning line includes a lighting scanning line driving unit and a light-off scanning line driving unit. According to this, the timing of the lighting scan and the extinction scan can be set for each of the first, second, and third pixels. In other words, the lighting timing setting within one frame can be made different for each of the first, second, and third pixels. Therefore, for example, the lighting time zone having the maximum power ratio time of 2 can be shifted by these pixels. Therefore, it is possible to eliminate the state where current is required to be the maximum at the past. Note that the first, second, and third variable clock frequency generation circuits are configured so that, for example, when the first, second, and third pixels correspond to RGB (red, green, and blue), 1 The lighting aperture ratio in the frame can be changed. Thereby, the color balance can be adjusted. This color balance adjustment is possible with a simpler configuration than when performing direct computation on the data of each pixel.

  Moreover, the time division gradation display according to the present invention is a display provided with the driving device as described above. Therefore, in this display, the state where current is required to be maximized can be solved.

  According to the time-division gray scale display driving apparatus and the time-division gray scale display equipped with such a driving apparatus according to the present invention, a lighting scan and a non-lighting scan for each of the first, second, and third pixels. Can be set, so that the maximum value of the current flowing through the display can be suppressed.

  As an embodiment of the present invention, a lighting period in each of the first color pixels by the first lighting scanning line driving unit and the first lighting scanning line driving unit, the second lighting scanning line driving unit, and the first lighting scanning line driving unit The lighting period in each of the second color pixels by the second unlit scanning line driving unit, and each of the third color pixels by the third lighting scanning line driving unit and the third unlit scanning line driving unit Is a set of each lighting period having a power ratio time of 2 within one frame, and the time period occupied by the maximum lighting period within the power ratio of 2 is within each frame. The first color pixel, each of the second color pixels, and each of the third color pixels may be set so as not to overlap with each other. The lighting timings of the first, second, and third pixels are set in advance.

  Further, as an embodiment, each of the lighting periods of the power ratio time of 2 may be each of the lighting periods having a time ratio of 1, 2, 4, 8, 16, and 32. According to this, it is possible to display 64 gradations. Almost sufficient gradation expression is realized.

  Further, as an embodiment, the lighting periods of the power-of-two ratio time of 2 may be assumed to be not in ascending order or descending order. This is to prevent the so-called pseudo contour generation in the time division gradation display method.

  As an embodiment, the one frame may be 1/60 second. It is one frame time that matches a conventional display device.

  Based on the above, embodiments of the present invention will be described below with reference to the drawings. First, a form as a comparative reference example for the embodiment will be described with reference to FIG.

  FIG. 8 is a diagram illustrating a configuration of a time division gradation display as a comparative reference example. The display includes a video signal driving unit 11, a lighting scanning line driving unit 12, a light-off scanning line driving unit 13, and a panel 14. The panel 14 has pixels AA, AB, AC,..., BA, BB, BC,. When each data is given from the data lines 15R, 15G, and 15B of the video signal driving unit 11, these pixels are turned on by a lighting driving signal from the scanning line 16 of the lighting scanning line driving unit 12, and this lighting state is The extinguishing scanning line driving unit 13 changes to the extinguishing state by the extinguishing driving signal from the scanning line 17. In the following description, in addition to the scanning lines 16 and 17 for supplying drive signals, horizontal arrangements such as pixels AA, AB, AC,... Are also referred to as scanning lines (or lines: that is, scanning lines as display images). Call.

  Each of the pixels AA, AB, AC,..., BA, BB, BC,... Can take only one of a lighting state and a non-lighting state, and there is no intermediate state. As a well-known display panel in which pixels having such properties are formed in a matrix, there are a PDP and an organic EL panel. In order to express a halftone as a display, each pixel AA, AB, AC,..., BA, BB, BC,. .

  In this example, the pixels on the panel 14 are arranged such that the first column pixels AA, BA,... In the vertical direction are red (R) pixels, and the second column pixels AB, BB,. It is assumed that the column pixels AC, BC,... Are blue (B) pixels, and so on. Each pixel AA, AB, AC,..., BA, BB, BC,... Is connected with a power line (not shown) in addition to the data line and the scanning line. In order to maintain the state, a current flows through each pixel through the power line.

  Looking beyond the panel 14, the video signal driver 11 has a shift register structure, whereby a video signal (binary) is loaded for each line of the subframe, and the video signal for each loaded line. Are provided to the panel 14 by data lines 15R, 15G, 15B,. The shift register is shifted by a clock input for loading data for each line.

  The lighting scanning line driving unit 12 loads the lighting signal and shifts the lighting signal from the top to the bottom by the lighting scan clock, thereby outputting the lighting driving signal to each scanning line 16. Each of the pixels in one horizontal row connected to the scanning line 16 to which the drive signal is output is determined by the data value from the data lines 15R, 15G, 15B,. If it is)

  The unlit scanning line drive unit 13 outputs the unlit driving signal to each scanning line 17 by loading the unlit signal and shifting it from top to bottom by the unlit scan clock. The pixels in one horizontal row connected to the scanning line 17 to which the drive signal is output are turned off all at once regardless of the lighted / lighted state at that time.

  FIG. 9 is a diagram showing a time-series change in lighting / extinguishing in the time-division gray scale display shown in FIG. 8 and a current value in one frame flowing through the pixels of the entire panel 14 at that time. .

  As shown in the upper diagram of FIG. 9, one frame is divided into several (here, six) subframes SF1 to SF6. Here, for convenience, the subframe is defined as a period from when the lighting scan starts at the top of the panel 14 until the next lighting scan starts. One frame is, for example, 1/60 seconds, but may be other than that while considering that surface flicker does not occur.

  When the lighting scan (displayed by a solid line in the figure) 21 starts in the subframe SF1 and the lighting drive signal moves downward, lighting is started for each scanning line accordingly (of course, a signal instructing the data line to light up). Only the pixels with are lit). Next, when an extinction scan (indicated by a dotted line in the figure) 22 starts after one lighting period and the extinguishing drive signal moves downward, all the scanning lines are extinguished accordingly. In other words, a period between the lighting scan 21 and the light extinction scan 22 (displayed as a dot pattern in the figure) is a period during which the lighting state can be achieved.

  The above-described lighting and extinguishing are basically the same in the subframes SF2, SF3, SF4, SF5, and SF6. However, the period until the turn-off scan 22 follows the turn-on scan 21 (that is, the turn-on period) is a power-on ratio time of 2 lighting periods, 4 lighting periods, 8 lighting periods, 16 lighting periods, and 32 lighting periods, respectively. ing. In this way, if one frame is constituted by a set of lightings having power-of-two ratio times, intermediate luminance can be expressed. For example, if the luminance is 10, only the subframes SF2 and SF4 are turned on and the other subframes are turned off. If the luminance is 54, only the subframes SF2, SF3, SF5, and SF6 are turned on and the other subframes are turned off. The gradation can be expressed by turning off the frame. Thus, in this case, 64 gradations can be displayed from luminance 0 to luminance 63 (in actuality, each pixel is an R pixel, a G pixel, and a B pixel. In this sense, “luminance” is appropriate. Not for convenience.)

  The current in one frame that flows to the pixels of the entire panel 14 when the light is turned on / off is maximum (that is, when the luminance is 63) as shown in the lower diagram of FIG. The transition of the current as shown in the lower part of FIG. 9 can be understood by looking at the length when the dot pattern is vertically cut at each time point in the upper part of the figure.

  As can be seen from this current transition, the maximum current in this configuration is limited to the vicinity of subframes SF5 and SF6 in one frame. Naturally, the panel 14 needs to include a power supply unit (not shown) corresponding to the maximum current.

Next, FIG. 1 is a diagram showing a configuration of a time-division gradation display according to one aspect (principal form) of the present invention. This display includes color signal driving units 1R, 1G, and 1B, lighting scanning line driving units 2R, 2G, and 2B, unlit scanning line driving units 3R, 3G, and 3B, and a panel 4. The panel 4 has pixels aa, ab, ac,..., Ba, bb, bc,. In the vertical direction, the first column pixels aa, ba,... Are R pixels, the second column pixels ab, bb,... Are G pixels, and the third column pixels ac, bc,. Hereinafter, the same repetition is assumed.

  That is, this time-division gray scale display has three color signal drivers 1R, 1G, 1B instead of the video signal driver 11, and a lighting scanning line driver as compared with the display shown in FIG. 12 is replaced with three lit scanning line driving units 2R, 2G, and 2B, and further replaced with the unlit scanning line driving unit 13 and having three unlit scanning line driving units 3R, 3G, and 3B. It is. As shown in the figure, the connection destinations of the lit scanning line driving units 2R, 2G, and 2B are only the pixels of the corresponding colors, respectively, and this is for the unlit scanning line driving units 3R, 3G, and 3B. It is the same.

  When the data is supplied from the data line 5R of the video signal driving unit 1R, the R pixels aa, ba,... Are turned on by a lighting driving signal from the scanning line 6R of the lighting scanning line driving unit 2R. The light is turned off by the light-off drive signal from the scanning line 7R of the scanning line driving unit 3R. Similarly, when data is supplied from the data line 5G of the video signal driving unit 1G, the G pixels ab, bb,... Are turned on by a lighting driving signal from the scanning line 6G of the lighting scanning line driving unit 2G. Is turned off by the turn-off drive signal from the scanning line 7G of the turn-off scanning line driving unit 3G. Similarly, the B pixels ac, bc,... Are lit by a lighting drive signal from the scanning line 6B of the lighting scanning line driving unit 2B when data is supplied from the data line 5B of the video signal driving unit 1B. Is turned off by the turn-off drive signal from the scanning line 7B of the turn-off scanning line driving unit 3B.

  In addition, in the following, in addition to the scanning lines 6R and 7R for supplying drive signals, horizontal arrangements such as pixels aa, ab, ac,... Are also scanning lines (or lines: that is, scanning lines as display images). Call it. Similarly to the description with reference to FIG. 8, each of the pixels aa, ab, ac,..., Ba, bb, bc,. Further, the conditions of the power supply line of each pixel are the same as described in the form shown in FIG.

  The internal configurations of the color signal driving units 1R, 1G, and 1B are substantially the same as those of the video signal driving unit 11 in FIG. However, since each color is independent, the number of shift registers is 1/3. The internal configurations of the lighting scanning line driving units 2R, 2G, and 2B are the same as those of the lighting scanning line driving unit 12 in FIG. The internal configuration of each of the unlit scanning line driving units 3R, 3G, and 3B is the same as that of the unlit scanning line driving unit 13 in FIG.

  FIG. 2 shows a time-series change in lighting / extinguishing of the R pixel in the time-division gray scale display shown in FIG. 1, and current values in one frame flowing through the entire R pixel of the panel 4 at that time. FIG.

  2 differs from FIG. 9 in the order of each subframe in the frame. In the case shown in FIG. 9, the lighting period ratio is arranged in ascending order of 1, 2, 4, 8, 16, 32, but here, it is set to 1, 8, 16, 4, 32, 2. Such a change is realized by changing the timing of the turn-on scan 21R and the turn-off scan 22R as desired. The transition of the current in one frame flowing through the entire R pixel of the panel 4 (when it is maximum) by the order of the subframes after such change is as shown in the lower side of FIG. The current value in the current peak period is naturally 1/3 of the peak value in the case shown in FIG.

  FIG. 3 shows a time-series change of G pixel on / off in the time-division gray scale display shown in FIG. 1, and the current value in one frame flowing through the entire G pixel of the panel 4 at that time. FIG.

  The difference of FIG. 3 from FIG. 9 is also the order of each subframe in the frame. Here, it was set to 16, 1, 32, 8, 4, 2. With such a subframe order, the transition of current in one frame flowing through the entire G pixel of the panel 4 (when it is maximum) is as shown in the lower side of FIG. The current value in the current peak period is 1/3 of the peak value in the case shown in FIG.

  FIG. 4 shows a time-series change in lighting / extinguishing of the B pixel in the time-division gradation display shown in FIG. 1, and current values in one frame flowing through the entire B pixel of the panel 4 at that time. FIG.

  The difference of FIG. 4 from FIG. 9 is also the order of each subframe in the frame. Here, it is set to 32, 2, 4, 8, 16, 1. With such a subframe order, the transition of the current in one frame flowing through the entire B pixel of the panel 4 (when it is maximum) is as shown in the lower side of FIG. The current value in the current peak period is 1/3 of the peak value in the case shown in FIG.

It is possible to know the transition of the current flowing through the pixels of the entire panel 4 within one frame by adding the transition of the current within one frame (when the maximum value) shown in FIGS. it can. This is shown in FIG. FIG. 5 is a diagram showing a current transition (in the maximum case) within one frame in the time-division gradation display according to one embodiment (principal embodiment) of the present invention. As shown in FIG. 5, in this embodiment , the peak current value can be suppressed to about 70 to 80% as compared with the case of FIGS. 8 and 9 which are comparative reference examples. Therefore, a small power supply unit is sufficient.

As can be seen from the above description, the above effect in the form status of this, each R, G, lighting the scanning line driver 2R for each pixel of the B, 2G, 2B extinguished scan line driver 2R constituting the scanning line It originates in having set it as the structure provided with 2G and 2B. Thereby, the timing of the lighting scans 21R, 21G, 21B and the extinguishing scans 22R, 22G, 22B can be set independently for each R, G, B pixel. Therefore, the lighting time zone having the maximum power ratio time of 2 is shifted by these pixels.

  In addition, the order of each sub-frame as shown in FIG.2, FIG.3, FIG.4 is not restricted to this. It is important to set at least the lighting time zones of the power-of-two ratio time at the maximum so that they do not overlap three times. As one example, it is conceivable to maintain the subframes in ascending order as shown in FIG. 9 and change the phase for each R, G, B pixel. However, the arrangement of the lighting period ratios in the ascending order and descending order as the sub-frame configuration tends to generate so-called pseudo contours, so care must be taken. The pseudo contour means that, for example, a luminance difference is small, such as luminance 31 and luminance 32, but a contour line can be seen at the luminance difference boundary on the display image because the lighting period in the frame is greatly different. . Since this is particularly a problem with moving images, it is safe to arrange lighting period ratios with no regularity as shown in FIGS.

  In the above description, the case where 64 gradations are set by setting subframes has been described. However, fewer gradations and more gradations can be realized by changing the number of subframes in one frame.

Next, FIG. 6 the functions that can be added to form state described above will be described with reference to FIG. FIG. 6 shows a case in which the time-series change in lighting / extinguishing of the R pixel shown in FIG. 2 and the current flowing through the entire R pixel of the panel 4 at that time occur in a time-compressed manner within one frame. Show. Such a time compression operation is realized only by increasing the frequency of the light-on scan clock to the light-on scan line driver 2R and the light-off scan clock to the light-off scan line driver 3R. That is, as can be seen from the figure, the speed of the turn-on scan 21Ra and the turn-off scan 22Ra is increased.

  Similarly, if the frequency of the light-on scan clock to the light-on scan line drive unit 2G and the light-off scan clock to the light-off scan line drive unit 3G are increased, the time-series changes in G pixel on / off shown in FIG. , And the current flowing through the entire G pixel of the panel 4 at that time occurs in a time-compressed manner within one frame. This is similar to the case of the B pixel in FIG.

  Therefore, the color balance of the display can be adjusted using such an operation. That is, if the lighting aperture ratio in one frame is reduced as shown in the upper side of FIG. 6, red is suppressed in this case. Similarly, green or blue can be suppressed.

FIG. 7 shows a specific configuration. FIG. 7 is a diagram showing a configuration example that can be added to one embodiment (principal embodiment) of the present invention for color balance adjustment. The variable frequency clock generation circuits 71R, 71G, 71B change the output clock frequency according to the adjustment signal from the color balance adjustment unit 72. The frequency-changed clocks are respectively guided to the lit scanning line driving unit 2R and the unlit scanning line driving unit 2R. The higher the frequency, the more the color assigned to the drive unit to which the clock is input is suppressed.

  The color balance adjustment by such a configuration has an advantage that a very simple configuration is sufficient as compared with the case where the calculation is directly performed on the color signal and the video signal.

The figure which shows the structure of the time division | segmentation gradation display according to one form (principal form) of this invention. The figure which shows the time-sequential change of lighting / extinction of R pixel in the time division gradation display shown in FIG. 1, and the value of the electric current which flows into the whole R pixel of the panel 4 at that time (maximum case). The figure which shows the time-sequential change of lighting / extinction of G pixel in the time division gray scale display shown in FIG. 1, and the value (in the case of the maximum) of the electric current which flows into the whole G pixel of the panel 4 at that time. The figure which shows the time-sequential change of lighting / extinction of B pixel in the time division gray scale display shown in FIG. 1, and the value (in the case of the maximum) of the electric current which flows into the whole B pixel of the panel 4 at that time. The figure which shows the electric current transition in the 1 time frame (however, it is the largest ) in the time division gradation display according to one form (principal form) of the present invention. The figure which shows the case where the time-sequential change of R pixel lighting / extinguishing shown in FIG. 2 and the electric current which flows into the whole R pixel of the panel 4 at that time generate | occur | produced in time compression each. The figure which shows the structural example which can be added to one form (principal form) of this invention for color balance adjustment. The figure which shows the structure of the time division gradation display as a comparative reference example. The figure which shows the value of the electric current which flows into the pixel of the whole panel 14 at that time, and the time-sequential change of lighting / extinction in the time division gradation display shown in FIG.

Explanation of symbols

  1R, 1G, 1B... Color signal driving unit, 2R, 2G, 2B... Lighting scanning line driving unit, 3R, 3G, 3B .. extinguishing scanning line driving unit, 4 ... panel, 5R, 5G, 5B. 6G, 6B... Scanning lines, 7R, 7G, 7B... Scanning lines, 71R, 71G, 71B... Variable frequency clock generation circuit, 72.

Claims (6)

The first color pixels of the scan line having the first, second, and third color pixels are moved from top to bottom for each scan line in accordance with the first data from the first data lines. A first lighting scanning line driving unit capable of lighting;
A first light-off scanning line drive unit capable of turning off each first color pixel turned on by the first light-on scanning line drive unit from top to bottom for each scanning line;
A second lighting scanning line driving unit capable of lighting each second color pixel of the scanning line from top to bottom for each scanning line according to second data from each second data line;
A second light-off scanning line drive unit capable of turning off each of the second color pixels turned on by the second light-on scanning line drive unit from top to bottom for each scanning line;
A third lighting scanning line driving unit capable of lighting each third color pixel of the scanning line from top to bottom for each scanning line according to the third data from each third data line;
A third unlit scanning line drive unit capable of turning off each of the third color pixels lit by the third lit scanning line drive unit from top to bottom for each scanning line;
A first color signal driving unit that supplies the first data to the first color pixels via the first data lines;
A second color signal driving unit that provides each of the second data via the second data line for each of the second color pixels;
A third color signal driving unit for supplying the third data to the third color pixels via the third data lines ;
A speed at which the first lighting scanning line driving unit lights the scanning lines from top to bottom, a speed at which the second lighting scanning line driving unit lights the scanning lines from top to bottom, and A clock signal is supplied to each of the first, second, and third lighting scanning line driving units so that the third lighting scanning line driving unit varies the speed at which the scanning lines are lit from top to bottom. A drive device for a time-division gray scale display, comprising: a first, a second and a third variable clock frequency generation circuit for supplying . The lighting period in each first color pixel by the first lighting scanning line driving unit and the first lighting scanning line driving unit, the second lighting scanning line driving unit and the second lighting scanning line driving A lighting period in each second color pixel by the unit, and a lighting period in each third color pixel by the third lighting scanning line driving unit and the third extinction scanning line driving unit, respectively, It is a set of each lighting period of power ratio time of 2 within one frame,
The time period that the maximum lighting period of the power-of-two ratio time occupies in one frame is a triple of each first color pixel, each second color pixel, and each third color pixel. The time-division gray scale display driving device according to claim 1, wherein the driving device is set so as not to overlap.   3. The time-division gradation display display according to claim 2, wherein each lighting period of the power-of-two ratio time is each lighting period of a time ratio of 1, 2, 4, 8, 16, and 32. Drive device.   3. The time division gray scale display driving apparatus according to claim 2, wherein the lighting periods of the power-of-two ratio time are not in ascending order or descending order.   3. The time division gray scale display driving apparatus according to claim 2, wherein the one frame is 1/60 second. The time division gray scale display driving device according to claim 1,
And a panel connected to and driven by the time-division gray scale display driving device.

Images