TWI571847B - Display driving apparatus, display device and method for correcting display data - Google Patents

Description

Display driving device, display device, display data correction method Field of invention

The present invention relates to a display driving device, a display device, and a display data correction method, and more particularly to a display panel driving technology. The display panel is provided with a plurality of data lines and scanning lines, and is formed correspondingly at respective intersections of the data lines and the scanning lines. Pixel.

Background of the invention

As a display panel for displaying an image, a display device using an OLED (Organic Light Emitting Diode), a display device using an LCD (Liquid Crystal Display), or the like is known. In many display devices, there are display portions each of which is provided with a plurality of data lines and scan lines, each of which is connected to a plurality of pixels arranged in a column direction, the scan lines being connected to the row direction A plurality of pixels are arranged, and pixels are formed correspondingly at respective intersections of the data lines and the scan lines.

In the case of so-called line sequential scanning, the scan line driver sequentially selects the scan lines, and the data line driver outputs one line of data line drive signals to the respective data lines, thereby controlling the display of each point, that is, the pixels.

Prior art literature Patent literature

Patent Document 1: Japanese Patent Laid-Open No. Hei 9-232074

Patent Document 2: Japanese Laid-Open Patent Publication No. 2004-309698

In the above-mentioned Patent Document 1, a technique for improving delay in pixel light emission enhancement caused by a parasitic capacitance of a display panel using a so-called cathode reset method is disclosed, in which all scan line connections are made when scanning is switched to the next scanning line. To the reset potential.

In the above Patent Document 2, a technical solution is disclosed in which, when a display signal is supplied to a data electrode, all the electrodes are connected to a reset potential and then connected to a preset potential as means for reducing overshoot and undershoot of the display signal.

Summary of invention

Here, for example, as a passive matrix driving OLED display device, a cathode reset method is employed, and a constant current driving of a data line is also considered, and a driving mode of gradation is controlled using a width (on-period) of a data line driving signal of a constant current.

In this case, when one row of pixel gradation mixing is selected and driven, luminance unevenness due to potential fluctuation of the data line and the scanning line is generated on the line, and there is a problem that image quality is degraded.

When the OLED display device is driven, the data line becomes a constant current drive, and the scan line becomes a state in which only the selected row is grounded. Then, on the data line and A parasitic capacitance exists in the pixel between the scanning lines, and charging and discharging of the parasitic capacitance occurs according to the potential fluctuation of the data line and the scanning line. It is considered that the charge and discharge have an influence on the current of the organic EL element to be lit, and luminance unevenness is generated.

It is an object of the present invention to reduce or eliminate such brightness unevenness and improve image quality.

First, in the display driving device according to the present invention, the display portion is provided with a plurality of data lines and scan lines, each of which is connected to a plurality of pixels arranged in the column direction, the scan lines being connected to the row direction. The plurality of pixels arranged are formed with pixels corresponding to respective intersections of the data lines and the scanning lines, and the display unit drives the data lines in accordance with gradation values of corresponding pixels. The display drive device includes a current setting unit configured to cause a data line drive signal for driving the respective data lines to be a constant current signal based on a set brightness, a correction value generation unit to generate a correction value for display data, and a drive control signal generation The correction processing of the correction value generated by the correction value generation unit is performed on the display data, and a drive control signal for driving the predetermined data line drive signal is generated based on the display data after the correction processing. Further, the correction value generation unit uses a difference between the set brightness and the reference brightness and a lighting in a display data unit corresponding to one line of the scan line when the set brightness is lower than the reference brightness a rate, a correction value is generated, and when the set brightness is higher than the reference brightness, a correction value is generated using a difference between the set brightness and the reference brightness and a non-lighting rate in the display data unit .

The display driving device applies a constant current signal during the driving period based on the gradation value to the data line, but depending on the lighting rate or the overall brightness on one line, the brightness of the lighting pixel of a certain line becomes higher or lower. The brightness of the original brightness changes, resulting in uneven brightness in the image. The occurrence of the change in luminance changes depending on the set brightness or the lighting rate of the line. More specifically, in the case where the setting luminance is higher than the reference luminance (the luminance unevenness is a visually unprobable predetermined luminance (or predetermined luminance range)), the lower the lighting rate is, and the difference between the luminance and the reference luminance is set. The larger the light, the higher the brightness of the lighting pixels. Further, in the case where the set brightness is lower than the reference brightness, the lower the lighting rate is, and the larger the difference between the set brightness and the reference brightness is, the lower the brightness of the lighting pixel is.

In order to cope with such a phenomenon, a parameter of the difference between the set brightness and the reference brightness and a parameter of the lighting rate (or non-lighting rate) in the display data unit are used to generate a correction value to correct the display data. .

Secondly, in the display driving device according to the present invention, it is preferable that the drive control signal generating unit corrects a direction in which a driving period of the data line driving signal is shortened as the correction processing.

The unevenness of the brightness on the screen is generated due to the difference in luminance between pixels which should be the same brightness. To eliminate the unevenness of the brightness, the display data (gradation) of the pixel whose brightness is increased is lowered, or the brightness is lowered. The display data (grayscale) of the pixel that is lowered can be increased. In this case, all the corrections are performed in a direction in which the pixel gradation in which the luminance is increased, that is, in the direction in which the driving period of the data line driving signal is shortened.

Thirdly, in the display driving device according to the present invention described above, the point The lamp rate is obtained by integrating the gradation values indicated by the respective display data in the display data unit, dividing the integrated value by the number of gradations, and dividing the obtained value by the number of display data in the display data unit. The obtained value, the non-lighting rate is 1 - the lighting rate.

The lighting rate is the ratio of the pixels being lit in a row of pixels, but not only the ratio of the number of lighting pixels, but also the value of the gradation of each lighting pixel.

According to a fourth aspect of the invention, in the display drive device of the present invention, the correction value generation unit generates a correction value by using the input display data as a predetermined number of digit gradation values, and the drive control signal generation unit inputs the correction value. As the display data of the predetermined number of bits gradation value, correction processing using the correction value generated by the correction value generating unit is performed.

By performing correction value generation and correction on the display data of the stage in which the gradation value is expressed by a predetermined number of bits, various stages of correction can be selected.

According to a fifth aspect of the invention, in the display drive device of the present invention, the correction value generation unit converts the input predetermined number of digit gradation values into a count value corresponding to the drive period, and displays display data in the state as a target. To generate a correction value, the drive control signal generating unit generates display data in a state in which the input predetermined number of digit gradation values are converted into a count value corresponding to the drive period, and is generated using the correction value. The correction processing of the correction value generated by the part.

Correction value generation and correction are performed by using display data in a state in which the gradation value has been converted into a count value corresponding to the drive period as an object, It is possible to correct with a finer gradation resolution than the gradation resolution of the display data before conversion.

A display device according to the present invention includes: a display portion configured to respectively configure a plurality of data lines and scan lines, the data lines being connected to a plurality of pixels arranged in a column direction, the scan lines being connected to the row direction a plurality of pixels, pixels are formed corresponding to respective intersections of the data lines and the scan lines; a display driving unit drives the data lines according to gray values of corresponding pixels; and a scan line driving unit The scan line applies a scan signal. Further, the display drive unit includes a configuration as the display drive device.

That is, as the display device including the display driving device described above, a display device capable of reducing or eliminating display unevenness is realized.

A display data correction method according to the present invention is for generating a driving period based on a corresponding pixel gradation value in a case where a data line driving signal for driving the respective data lines is supplied to a display portion as a constant current signal based on a set luminance a driving control signal for specifying the data line driving signal, wherein the display portion is respectively configured with a plurality of data lines and scan lines, wherein the data lines are each connected to a plurality of pixels arranged in a column direction, and the scan lines are connected To a plurality of pixels arranged in the row direction, pixels are formed corresponding to respective intersections of the data lines and the scan lines. The display data correction method is configured to use a difference between the set brightness and the reference brightness and a lighting rate in a display data unit corresponding to one line of the scan line when the set brightness is lower than the reference brightness And generating a correction value of the display data, wherein, when the set brightness is higher than the reference brightness, using a difference between the set brightness and the reference brightness, and a non-lighting rate in the display data unit, A correction value of the display data is generated, and correction processing of the display data is performed using the generated correction value.

That is, in order to eliminate or reduce the luminance unevenness caused by the luminance change caused by the set luminance or the lighting rate, the correction of the display data based on the correction value of the set luminance or the lighting rate is generated.

According to the present invention, it is possible to eliminate or reduce the luminance unevenness caused by the luminance change caused by the set luminance or the lighting rate by the correction of the display data, and it is possible to improve the display quality.

1‧‧‧ display device

2‧‧‧MPU

2a, 44a‧‧‧Correction value generation unit

2b‧‧‧Display Data Correction Department

10‧‧‧Display Department

20‧‧‧Controller IC

21‧‧‧ Cathode Driver

31‧‧‧Drive Control Department

32‧‧‧Display data storage department

33‧‧‧Anode Driver

33a‧‧‧Reference current generation unit

33b‧‧‧current output department

41‧‧‧MPU interface

42‧‧‧Command decoder

43‧‧‧Oscillation circuit

44‧‧‧Time controller

44b‧‧‧Drive Signal Generation Unit

45‧‧‧ Current Setting Department

51‧‧‧Timed generation circuit

52‧‧‧ buffer

53‧‧‧Selector

54‧‧‧ Grayscale Table Storage

55‧‧‧Subtractor

60 (60-1~60-256)‧‧‧Latch circuit

61‧‧‧ counter

62 (62-1~62-256)‧‧‧Comparative circuit

65‧‧‧Brightness correction calculation unit

66‧‧‧Revised initial value storage for calculation

80‧‧‧Voltage variable part

81, 85‧‧‧P-channel FET (Field Effect Transistor)

82‧‧‧N-channel FET

83‧‧‧Differential Amplifier

84‧‧‧resistance

86, 87, SWA1~SWA256, SWC1~SWC128‧‧‧ switch

ADS, ADS1, ADS2‧‧‧ drive control signals

AR1, AR2‧‧‧ area

AR3‧‧‧ area; non-lighting pixels

CA‧‧‧cathode driver control signal

CK‧‧‧ clock signal

CoefP, coefM‧‧ coefficient

DL, DL1~DL256‧‧‧ data line

DT, DT’‧‧‧ display data

G‧‧ ‧ pixels

Hkp, hkm‧‧‧ correction factor

I1~I256‧‧‧ Constant current source

IS‧‧‧ current value control signal

IR‧‧‧reference current

Lx, Ly‧‧‧

Lum‧‧‧Brightness setting

M1~M8‧‧‧Light change area

Q1~Q128‧‧‧Output terminal

SD‧‧‧ scan direction

S100-S108, S200-S208‧‧‧ steps

SH‧‧‧ correction value

SL, SL1~SL128‧‧‧ scan line

Thr‧‧‧reference brightness

VHA, VHC, VR‧‧‧ voltage

1 is a block diagram of a display device and an MPU according to an embodiment of the present invention.

2 is an explanatory view equivalently showing an anode driver, a cathode driver, and a pixel in the display device of the embodiment.

3 is an explanatory view of a circuit configuration of an anode driver of the embodiment.

Fig. 4 is an explanatory diagram of a state in which a change in luminance is generated on the display.

5A-5D are explanatory diagrams of luminance changes with respect to overall luminance and no dots.

6A-6D are explanatory views of the cause of the change in luminance and the cause of the change in luminance.

7A-7D are explanatory views of a correction operation of the embodiment.

FIG. 8 is an explanatory diagram of an operation of the correction processing of the embodiment.

Fig. 9 is an explanatory diagram of a lighting rate used in the embodiment.

Fig. 10 is a block diagram of the controller IC of the embodiment.

Fig. 11 is a block diagram of a timing controller of the first embodiment.

12A-12B are explanatory views of a gradation meter and an anode output of the embodiment.

Fig. 13 is a flowchart of the correction processing of the first and third embodiments.

14A-14C are explanatory diagrams of correction coefficients of the embodiment.

Fig. 15 is a block diagram of a timing controller of the second embodiment.

Fig. 16 is a flowchart of the correction processing of the second embodiment.

17A-17B are explanatory views of a third embodiment.

detailed description

Hereinafter, embodiments of the present invention will be described in the following order.

<1. Structure of Display Device and Display Drive Device According to Embodiment> <2. Explanation of the change in brightness generated on the display> <3. Correction Process of Embodiment> <4. First embodiment> <5. Second embodiment> <6. Third embodiment> <7. Summary and Modifications> <1. Structure of Display Device and Display Drive Device According to Embodiment>

FIG. 1 shows a display device 1 according to an embodiment and an MPU (Micro Processing Unit) 2 that performs display operation control of the display device 1.

The display device 1 has a display unit 10 constituting a display screen, a controller IC (Integrated Circuit) 20, and a cathode driver 21.

Further, the display device 1 is an embodiment of a display device corresponding to the scope of the patent application of the present invention. Further, the controller IC 20 is an embodiment of a display driving device (or display driving unit) equivalent to the scope of the present invention.

The display section 10 is provided with a plurality of data lines DL and scan lines SL, respectively, and pixels are formed at respective intersections of the data lines DL and the scan lines SL. For example, 256 data lines DL1 to DL256 and 128 scanning lines SL1 to SL128 are provided, and correspondingly, 256 pixels are arranged in the horizontal direction and 128 pixels are arranged in the vertical direction.

Therefore, the display unit 10 has 256 × 128 = 32768 pixels as pixels constituting the display image. In the present embodiment, each pixel is composed of a self-luminous element using an OLED. In addition, of course, the number of pixels, the number of data lines, and the number of scanning lines are merely illustrative examples.

Each of the 256 data lines DL1 to DL256 is connected to 128 pixels arranged in the column direction (vertical direction) of the display portion 10. Further, each of the 128 scanning lines SL1 to SL128 is connected to 256 pixels arranged in the row direction (horizontal direction).

A data line driving signal based on display data (gradation value) is applied to 256 pixels on a line selected from the data line DL to the scanned line SL, so that each pixel on the line is based on brightness (grayscale) based on display data. Perform light-emitting drive.

Further, "row" refers to a scan line or 256 pixel units connected to one scan line.

The controller IC 20 and the cathode driver 21 are provided to drive the display of the display portion 10.

The controller IC 20 has a drive control unit 31, a display data storage unit 32, and an anode driver 33. The anode driver 33 drives the data lines DL1 to DL256.

In this example, when a pulse signal (drive control signal ADS) having a time length based on gradation is applied from the drive control section 31, the anode driver 33 The data line DL is subjected to constant current output during a predetermined period of the drive control signal ADS. The constant current signal applied to the data line DL is referred to as a "data line drive signal."

That is, the display device 1 of the present example is a passive matrix driving OLED display device which employs a driving method of controlling the gradation by constant current driving of the data line DL and driving the width (on-period) of the data line with a constant current.

The drive control unit 31 communicates with the MPU 2 to command or display data, and controls the display operation based on the command. For example, when receiving the instruction to start the display, the drive control unit 31 performs timing setting accordingly, and applies the cathode driver control signal CA to the cathode driver 21 to start scanning of the scanning line SL.

Further, 256 data lines DL are driven from the anode driver 33 in synchronization with the scanning by the cathode driver 21. Regarding the driving of the data line DL by the anode driver 33, the drive control section 31 stores the display data received from the MPU 2 in the display data storage section 32 while providing the drive control signal ADS based on the display data at the above-described scanning timing. The anode driver 33 is supplied. In response to this, the anode driver 33 outputs a gradation-based data line driving signal to the data line DL.

By this control, the selected row, that is, each pixel on one scanning line SL to which the scanning signal of the selected level is applied from the cathode driver 21 is driven to emit light. Each line is driven by sequentially illuminating, thereby realizing one frame of image display.

Further, the current value of the data line drive signal output from the anode driver 33 is variably controlled by the current value control signal IS from the drive control unit 31. system.

The cathode driver 21 functions as a scanning line driving portion for applying a scanning signal from one end of the scanning line SL.

The cathode driver 21 is configured such that its Q1 output terminal to Q128 output terminal are connected to the scan lines SL1 to SL128, respectively. Then, as shown by the scanning direction SD, the scanning signals of the selection level are sequentially output from the Q1 output terminal to the Q128 output terminal, and the scanning lines SL1 to SL128 are scanned in the sequential selection state.

FIG. 2 is a view showing the configuration of the display unit 10, the anode driver 33, and the cathode driver 21 as equivalent circuits.

As shown in FIG. 2, in the display unit 10, pixels G are arranged at each intersection of the scanning line SL and the data line DL, and a display image is formed by pixels G arranged in a matrix. In Fig. 2, a pixel G is shown by a diode symbol indicating an organic EL element and a capacitance symbol indicating a parasitic capacitance.

Switches SWC1 to SWC128 are provided in the cathode driver 21 for selecting whether to connect the respective scan lines SL1 to SL128 to the voltage VHC or to the ground, respectively. The scan line SL in the non-selected state is connected to the voltage VHC, and the scan line SL of the selected scan object is connected to the ground. That is, in this case, the scanning signal of the selected level is in the ground potential state. The scanning lines SL1 to SL128 are sequentially grounded to be in a sequential selection state.

In the anode driver 33, constant current sources I1 to I256 and switches SWA1 to SWA256 are provided corresponding to the respective data lines DL1 to DL256.

For each of the data lines DL1 to DL256, the switches SWA1 to SWA256 are controlled by the drive control signal ADS so that the scan line SL of the selected state is 256 pixels G apply constant current (data line drive signal) from constant current sources I1 to I256 based only on the length of each display data (gray value)

FIG. 3 shows a more specific configuration example of the data line drive signal for supplying the constant current generated by the anode driver 33 according to the set current value to the data lines DL1 to DL256 only during the period based on the gradation of each pixel.

The reference current generating unit 33a and the current output unit 33b are provided in the anode driver 33. The reference current generating unit 33a includes a voltage variable unit 80, a differential amplifier 83, a P-channel FET (Field Effect Transistor) 81, an N-channel FET 82, and a resistor 84. The voltage VR from the voltage variable portion 80 is applied to the non-inverting input of the differential amplifier 83, and the inverting input is grounded through the resistor 84. The voltage VR of the voltage variable portion 80 is variably controlled by the current value control signal IS.

The output of the differential amplifier 83 is connected to the gate of the FET 82, the source of the FET 82 is connected to the inverting input of the differential amplifier 83, and the drain of the FET 82 is connected to the drain of the FET 81.

The FET 81 has a gate connected to the drain of the FET 81, a source connected to the voltage VHA, and a drain connected to the drain of the FET 82.

With this configuration, a reference current IR corresponding to the voltage VR flows between the source and the drain of the FET 81. That is, the current value of the reference current IR is variably controlled by the current value control signal IS.

In the current output portion 33b, switches 86, 87 and a P-channel FET 85 are provided corresponding to the respective data lines DL1 to DL256 for switching the state in which the data line DL is connected to the current source and the state connected to the ground.

Each FET 85 has a source connected to a voltage VHA and a drain connected to a switch 86.

The gate of each FET 85 is connected to the drain and gate of the FET 81.

By turning on the switch 86 and simultaneously turning off the switch 87, the respective data lines DL1 to DL256 are connected to the drains of the respective FETs 85.

Further, by turning off the switch 86 while turning on the switch 87, the respective data lines DL1 to DL256 are connected to the ground. Then, in this case, the FET 81 and each of the FETs 85 employ a current mirror structure. Therefore, when the switch 86 is turned on and the switch 87 is turned off, a data line driving signal of a constant current signal as a current value of the reference current IR is applied to the data line DL.

The switches 86, 87 are turned on or off in accordance with the drive control signal ADS from the drive control section 31. For example, when the switch 86 is a P-channel FET and the switch 87 is an N-channel FET, when the drive control signal ADS is at the L (Low) level, constant current supply is performed to the data line DL, and drive control is performed. When the signal ADS is at the H (High) level, the data line DL is grounded.

According to the above configuration, it can be understood that the constant current value as the data line drive signal applied to the data line DL is variably set by the current value control signal IS. Further, while the data line drive signal is applied to the data line DL, it is controlled by the drive control signal ADS. By setting the drive control signal ADS to a pulse signal based on the period length of the gradation value, the supply period of the constant current (data line drive signal) to the data line DL is controlled in accordance with the gradation value, thus, the pixel G It is possible to emit light with a gradation-based brightness.

Further, with respect to the correspondence relationship between the anode driver 33 shown in FIG. 3 and the anode driver 33 shown in FIG. 2, the switches 86, 87 of FIG. 3 can be equivalent to the switches SWA1 to SWA256 of FIG. The other parts of FIG. 3 may correspond to the constant current sources I1 to I256 of FIG.

<2. Explanation of the change in brightness generated on the display>

Here, the change in luminance generated on the display will be described.

FIG. 4 shows a case where the overall brightness is changed in accordance with the brightness setting of the display screen.

The overall brightness refers to the brightness of the entire picture, and the adjustment of the overall brightness usually refers to the adjustment of "dimmering" or "dimmer".

Then, the overall brightness changes as the constant current value of the data line driving signal changes.

In other words, the brightness is set according to the target, and the current value control signal IS is used to change the constant current value, thereby adjusting the overall brightness of the screen (see FIG. 3).

In FIG. 4, as such brightness setting, the screen states in five cases of the brightness setting values "40" to "80" (cd/m ² ) are schematically shown.

Further, it is assumed that a background portion and a character portion indicated by "ABC..." exist in each screen. This screen displays black characters on a high-brightness background, and the pixels forming the characters themselves are in a non-lighting state, and the pixels corresponding to the background other than the characters are in a lighting state. The lighting pixel is a pixel that provides a constant current (data line driving signal) based on the brightness setting in the operation illustrated in FIG. That is, all the pixels of the line without text are lit, and the lighting rate is the highest. The line involved in the displayed text has non-lighting pixels in the text portion, and the lighting rate is low (non-lighting rate is high). In addition, the line in which the "ABCDEFG" character is displayed has a lower lighting rate than the line in which the "ABCD" character is displayed (the non-lighting rate is high).

In the example of FIG. 4, it is assumed that the brightness setting "80" is the brightest picture, and the brightness setting "40" is the darkest picture.

In the screen of the brightness setting "60", set the lighting image of the brightness "60" The text "ABC..." is displayed as a background (non-lighting pixels), and the brightness unevenness on the screen is not particularly generated (even if it is generated, it is not clearly visible). However, if the brightness setting becomes high or low, a pixel portion that appears to have a brightness different from the original brightness is generated. This is expressed as the luminance change regions M1 to M8. The luminance change regions M1 to M8 are portions formed by a line in which a lighting pixel and a non-lighting pixel are mixed, that is, a lighting pixel in which a line of characters is displayed.

Since the luminance change regions M1 to M8 are generated, stripe luminance unevenness is generated on the screen other than the screen of the luminance setting "60".

Here, the luminances of the luminance change regions M1 to M8 are M3>M1, M4>M2, M5>M7, and M6>M8.

Further, M3>M4, M1>M2, M6>M5, M8>M7.

From the phenomenon shown in Fig. 4, the following three points (a), (b), and (c) can be summarized.

(a) There is a brightness setting that does not cause a change in luminance (the brightness setting "60" in the example in the figure). Further, such a brightness setting that does not cause a change in luminance (or an insignificant change in luminance) is referred to as "reference luminance".

(b) When the brightness setting is higher than the reference brightness, the lighting pixel of the row having a lower lighting rate increases in brightness (M3>M4, M1>M2).

(c) When the brightness setting is lower than the reference brightness, the brightness of the lighting pixels of the row having a lower lighting rate decreases (M6>M5, M8>M7).

That is, the degree of change in the luminance of the luminance change regions M1 to M8 is based on "the difference between the set luminance and the reference luminance" and the "lighting rate (or non-lighting ratio)".

This will be described using FIG. 5 and FIG. 6. In FIG. 5, the area AR1 is a row in which all pixels are lit, and the area AR3 is an area in which non-lighting pixels are. then, The area AR2 is a region of the lighting pixels of the row in which the non-lighting pixels (AR3) and the lighting pixels are mixed, and is a region in which pixels corresponding to the luminance changes of the luminance changing regions M1 to M8 are generated. In addition, the brightness of each area is indicated by a diagonal density.

The thinner the diagonal density, the higher the brightness.

Originally, the area AR2 has the same brightness as the area AR1, but in FIG. 5, a state in which the brightness is uneven due to the change in the brightness of the area AR2 is exhibited.

Here, FIG. 5A and FIG. 5B have the same brightness setting, and the brightness setting is higher than the reference brightness. FIG. 5A is a case where the number of non-lighting pixels is relatively small in one row, and FIG. 5B is a case where the number of non-lighting pixels is relatively large in one line. Case.

In addition, FIG. 5C and FIG. 5D have the same brightness setting, and the brightness setting is lower than the reference brightness. FIG. 5C is a case where the number of non-lighting pixels is relatively small in one row, and FIG. 5D is a case where the number of non-lighting pixels is relatively large in one row. Happening.

In the case of FIGS. 5A and 5B, the area AR2 is brighter than the area AR1. Further, the area AR2 of FIG. 5B is brighter than the area AR2 of FIG. 5A.

In the case of FIGS. 5C and 5D, the area AR2 is darker than the area AR1. Further, the area AR2 of FIG. 5D is darker than the area AR2 of FIG. 5C.

Here, first, attention is paid to the difference between FIG. 5A and FIG. 5B and the difference between FIG. 5C and FIG. 5D, and the luminance difference between the area AR1 and the area AR2 corresponds to the ratio of the non-lighting pixels in one line. This relationship is shown in Figure 6A. The horizontal axis of FIG. 6A is the ratio of the non-lighting pixels among all the pixels of one line, and the vertical axis is the luminance difference between the area AR1 and the area AR2.

The more the number of non-lighting pixels, the more the difference in brightness between the area AR1 and the area AR2 Big. That is, the greater the number of non-lighting pixels, the greater the change in brightness of the area AR2, and the more pronounced the brightness unevenness.

Focusing on the difference between FIG. 5A and FIG. 5C and the difference between FIG. 5B and FIG. 5D, it is understood that the luminance difference between the area AR1 and the area AR2 is affected by the brightness setting value.

This relationship is shown in Figure 6B. In FIG. 6B, the horizontal axis represents the luminance setting value, and the vertical axis represents the luminance difference between the region AR1 and the region AR2. The brightness setting value as the reference brightness is set to "thr" (hereinafter referred to as "reference brightness thr").

In the case where the luminance setting value is higher than the reference luminance thr, the higher the luminance setting value, the larger the luminance difference between the region AR1 and the region AR2. That is, the higher the brightness setting value, the larger the change in the brightness of the region AR2 in the direction in which the brightness becomes higher, and the more uneven the brightness is. Further, in the case where the luminance setting value is lower than the reference luminance thr, the luminance setting value is lower, and the luminance difference between the region AR1 and the region AR2 is larger. That is, the lower the luminance setting value, the larger the luminance change in the direction in which the luminance is lower in the region AR2, and the more uneven the luminance is.

In the case where the brightness setting value is higher than the reference brightness thr and lower than the reference brightness thr, the reason why the direction of the brightness change of the area AR2 changes is considered as follows.

6C is a waveform model of the data line driving signal in the case where the brightness setting value is lower than the reference brightness thr, and FIG. 6D is a waveform model of the data line driving signal in the case where the brightness setting value is higher than the reference brightness thr, the solid line is for the area AR1 The signal waveform of the pixel, the broken line is the signal waveform of the pixel for the area AR2.

First, basically, regarding the area AR1 where all pixels are lit, In a state in which the light-emission drive current is applied to all of the data lines DL, the current applied to the respective data lines DL flows to the selected scan line SL (the scan line grounded as described in FIG. 2) as indicated by the solid line.

On the other hand, with respect to the area AR2 included in the row having a low lighting rate, a current is applied to a part of the data lines DL, and the other data lines are grounded. In this case, the current applied to the data line DL corresponding to the lighting pixel also flows to the data line DL corresponding to the non-lighting pixel via the parasitic capacitance of the non-lighting pixel. Therefore, the parasitic capacitance of the non-lighting pixels among the capacitance components of the respective pixels indicated by the capacitance symbol in FIG. 2 is also charged, resulting in an increase in the load. As a result, a phenomenon occurs in which the current rise delay of the data line drive signal occurs.

Then, when the luminance setting value is low, that is, when the constant current value of the data line driving signal is low, the charging load on the parasitic capacitance of the pixel is relatively increased, and the rise of the waveform is significantly delayed as shown in FIG. 6C. Thus, the luminance is lowered in the pixels of the area AR2.

On the other hand, when the brightness setting value is higher than the reference brightness thr, the constant current value as the data line driving signal is high, whereby the charging load on the parasitic capacitance of the pixel is relatively reduced, as shown in FIG. 6D, the waveform rises. The delay is reduced. Then an overshoot occurs, the larger the constant current value, the longer the overshoot period, and the higher the partial brightness during the overshoot.

As described above, the constant current signal during the driving period based on the gradation value is applied to the data line by the display driving device, but depending on the lighting rate or the overall brightness on one line, the brightness of the lighting pixel of a certain line becomes high. The brightness changes at or below the original brightness, resulting in uneven brightness in the image.

That is, in the case where the set luminance is higher than the reference luminance thr, the lower the lighting rate is, and the larger the difference between the set luminance and the reference luminance thr is, the higher the luminance of the lighting pixel is. Further, in the case where the set luminance is lower than the reference luminance thr, the lower the lighting rate is, and the larger the difference between the set luminance and the reference luminance thr is, the lower the luminance of the lighting pixel is.

<3. Correction Process of Embodiment>

In the present embodiment, in order to cope with the luminance unevenness generated as described above, a parameter of setting a difference between the luminance and the reference luminance thr and a parameter of a lighting rate (or a non-lighting rate) for one line are used to generate a correction value for display. The data is corrected.

Further, the display data referred to in the embodiment is data indicating a predetermined number of bits of the gradation value of each pixel from the stage of transmission from the MPU 2 to the controller IC 20, or is converted into the controller IC 20 as will be described later. Data based on the state of the grayscale time length (target count value).

The correction of the display data of the present embodiment is generally performed in a direction in which the driving period of the data line driving signal is shortened.

Further, in the present embodiment, when the brightness setting value is higher than the reference brightness thr, the correction of the pixel brightness of the reduced area AR2 is performed, and when the correction value is calculated, the non-lighting rate is used in the calculation formula (=1) - lighting rate). On the other hand, when the brightness setting value is lower than the reference brightness thr, the correction of the pixel brightness of the reduced area AR1 is performed, and when the correction value is calculated, the lighting rate is employed in the calculation formula.

7A and 7B show the correction processing in the case where the luminance setting value is higher than the reference luminance thr.

For example, the luminance of the area AR2 shown in FIGS. 5A and 5B is higher than the case of the area AR1.

In this case, the pixels of the area AR2 are corrected to reduce the brightness. When the time length (pulse width) of the data line drive signal based on the original gradation value for the pixel of the area AR2 is set to the time length indicated by the broken line in FIG. 7A, the corrected pulse width is made a solid line. In the state shown, the display data is corrected. By shortening the supply time of the data line driving signal to the pixels of the area AR2 as described above, the luminance rise due to overshoot or the like is canceled, and as a result, the brightness is equal to that of the area AR1. Thus, the screen of the state of, for example, FIG. 5B is lowered or eliminated from the luminance unevenness as shown in FIG. 7B.

7C and 7D show the correction processing in the case where the luminance setting value is lower than the reference luminance thr.

For example, the luminance of the area AR2 shown in FIGS. 5C and 5D is lower than that of the area AR1.

In this case, instead of the area AR2, the pixels of the area AR1 are corrected to reduce the brightness.

When the time length (pulse width) of the data line drive signal based on the original gradation value of the pixel of the area AR1 is set to the time length indicated by the broken line in FIG. 7C, the corrected pulse width is shown by a solid line. Status, correct the display data. By shortening the supply time of the data line driving signal to the pixels of the area AR1 as described above, the brightness of the pixels of the area AR1 is lowered as the brightness of the area AR2 is reduced. Thus, a picture such as the state of FIG. 5D is lowered or as shown in FIG. 7D. Eliminate uneven brightness.

A correction value generating method for performing such correction will be described with reference to FIG.

8A and 8B are modes corresponding to the characteristics of Fig. 6B.

First, FIG. 8A is a case where the brightness setting value is higher than the reference brightness thr. The luminance difference generated in the areas AR1, AR2 is equal to the value obtained by multiplying the difference between the luminance setting value and the reference luminance thr by the coefficient coefP. The coefficient coefP corresponds to the slope of the characteristic of the portion of the reference luminance thr of Fig. 6B.

Fig. 8B is a case where the brightness setting value is lower than the reference brightness thr. The luminance difference generated in the areas AR1, AR2 is equal to the value obtained by multiplying the difference between the luminance setting value and the reference luminance thr by the coefficient coefM. The coefficient coefM corresponds to the slope of the characteristic of the portion below the reference luminance thr of Fig. 6B. Let the right side of FIG. 8A be the correction coefficient hkp, and the right side of FIG. 8B be the correction coefficient hkm. The correction coefficients hkp and hkm are coefficients including elements that set the difference between the luminance and the reference luminance thr.

The change in luminance corresponding to the lighting rate shown in Fig. 6A is considered below.

Fig. 8C is a case where the brightness setting value is higher than the reference brightness thr. (1-lighting rate) is the non-lighting rate. The luminance difference generated in the areas AR1, AR2 can be expressed as a non-lighting rate (=1-lighting rate) multiplied by the correction coefficient hkp.

Fig. 8D is a case where the brightness setting value is lower than the reference brightness thr. The difference in luminance generated in the areas AR1, AR2 can be expressed as the lighting rate multiplied by the correction coefficient hkm.

The amount of change in luminance includes an element that sets a difference between the brightness and the reference brightness thr, and a lighting rate (or non-lighting rate) element.

Therefore, it is possible to determine the display data as shown in FIGS. 8E and 8F. Corrected correction value. The correction value is the total amount of change in luminance which occurs according to the conditions for setting the brightness and the lighting rate, and can be said to be a correction amount corresponding thereto (the amount of the gradation value subtracted from the gradation value as the display data).

FIG. 8E is a case where the brightness setting value is higher than the reference brightness thr. The correction value is equal to the display data multiplied by the non-lighting rate (=1-lighting rate) and the correction factor hkp.

Fig. 8F is a case where the brightness setting value is lower than the reference brightness thr. The correction value is equal to the display data multiplied by the lighting rate and the correction factor hkm.

Therefore, the correction can be performed as shown in FIG. 8G.

That is, the correction value is subtracted from the display data as the corrected display data.

The correction processing of the present embodiment is to calculate the correction values shown in FIGS. 8E and 8F using the lighting rate of each line display data unit, and the gradation values of the respective pixels of the line are as shown in FIG. 8G. Subtract the correction value.

The lighting rate is described here.

In the present embodiment, the lighting rate of one line is calculated as follows.

Lighting rate = (the cumulative value of the data displayed in one line) / (the number of gray levels) / (the number of display data in one line)

That is, the lighting rate is obtained by integrating the gradation value indicated by the display data of each pixel of the display data unit, that is, one line, dividing the integrated value by the number of gradations, and dividing the obtained value by the number of display data of one line (pixels) Quantity) The resulting value.

This is illustrated in FIG. One line of the display section 10 is 256 dots (256 pixels), (the number of display data of one line) = 256.

Further, the display data of one dot is set to, for example, 8 bits, and represents 256 stages of gradation of "0/255" to "255/255", and the number of gradations is 256.

For example, in the line Lx, it is assumed that 110 points are grayscales of "0/255", that is, turned off, and 146 points are grayscales of "255/255", that is, lights are illuminated at high brightness.

In this case, the cumulative value of the data displayed on one line is equal to 255 × 146. Thus, the lighting rate of the line Lx is equal to (255 x 146) / 255 / 256 = 0.570.

Further, in the line Ly, 100 dots are illuminated with a grayscale of "255/255", and 156 dots are illuminated with a grayscale of "128/255".

In this case, the cumulative value of the data displayed on one line is equal to 255 x 100 + 128 x 156.

Thus, the lighting rate of the line Ly is equal to (255 x 100 + 128 x 156) / 255 / 256 = 0.697.

Thus, in the present embodiment, the lighting rate is not only the ratio of the lighting pixels to the non-lighting pixels, but the value of the gradation of each pixel.

Based on the lighting rate thus obtained, the non-lighting rate was obtained by (1-lighting ratio), the non-lighting rate was 0.430 in the line Lx, and the non-lighting rate was 0.330 in the line Ly.

<4. First embodiment>

The first embodiment will be described as a specific example for performing the above correction.

FIG. 10 shows the inside of the controller IC 20 that functions as a display driving device, and particularly shows the configuration in the drive control portion 31 in detail.

The MPU interface 41, the command decoder 42, the oscillation circuit 43, the timing controller 44, and the current setting unit 45 are provided in the drive control unit 31.

The MPU interface 41 is a interface circuit unit that performs various kinds of communication with the MPU 2 described above. Specifically, display data, a command signal, and a brightness setting value are transmitted and received between the MPU interface 41 and the MPU 2.

The instruction decoder 42 acquires an instruction signal transmitted from the MPU 2 to an internal register (not shown) and decodes the instruction signal. The instruction decoder 42 then makes the necessary notification to the timing controller 44 to perform the operation in accordance with the content of the acquired instruction signal. Further, the instruction decoder 42 stores the acquired display data in the display data storage unit 32.

The oscillation circuit 43 generates a clock signal CK for displaying drive control.

The clock signal CK is supplied to the display data storage section 32 and used as a clock for data writing and/or reading operations. In addition, the clock signal CK is used in the processing of the timing controller 44.

The current setting unit 45 acquires the brightness setting value indicated by the MPU 2 via the MPU interface 41. Then, the current value control signal IS is supplied to the anode driver 33 in accordance with the indicated brightness setting value.

As illustrated in Fig. 3, the constant current value as the data line drive signal is controlled by the current value control signal IS. That is, the overall brightness of the screen is controlled by the display unit 10 in accordance with an instruction from the MPU 2 (dimmer control).

Further, the current setting unit 45 transmits the brightness setting value indicated by the MPU 2 as the information for the correction processing to the timing controller 44.

The timing controller 44 sets the drive timing of the scanning line SL and the data line DL of the display unit 10. Then, the timing controller 44 outputs a cathode driver control signal CA to perform line scanning by the cathode driver 21.

Further, the timing controller 44 outputs a drive control signal ADS to the anode driver 33 to perform driving of the data line DL (as a constant current output of the data line drive signal). To this end, the display data is read from the display data storage unit 32, and the drive control signal ADS is generated based on the display data. In this way, the anode is driven The controller 33 outputs a constant current (data line drive signal) corresponding to the drive control signal to each pixel of the row at the scanning timing of each of the scanning lines SL.

In particular, in the present embodiment, as shown in the figure, the timing controller 44 has a correction value generating unit 44a and a drive control signal generating unit 44b as the anode driver 33.

The correction value generating unit 44a performs an operation shown in FIG. 8E or FIG. 8F for each display data unit corresponding to one line of the scanning line SL to generate a correction value.

The drive control signal generation unit 44b corrects the display data using the correction value generated by the correction value generation unit 44a, and generates a drive control signal ADS for driving each of the data lines DL based on the display data after the correction processing.

A specific configuration example of such correction value generation unit 44a and drive control signal generation unit 44b is shown in FIG.

In the configuration shown in FIG. 11, the luminance correction amount calculation unit 65 and the correction calculation initial value storage unit 66 function as the correction value generation unit 44a.

Further, the buffer 52, the selector 53, the gradation table storage unit 54, the subtractor 55, the latch circuit 60 (60-1 to 60-256), the counter 61, and the comparison circuit 62 (62-1 to 62-256) It functions as the drive control signal generating unit 44b.

The timing generation circuit 51 controls the operation timings of the respective components constituting the above-described correction value generation unit 44a and drive control signal generation unit 44b.

First, in the configuration of Fig. 11, operations other than the correction processing will be described.

The timing controller 44 acquires the display data DT stored in the above-described display data storage unit 32 into the buffer 52 in units of one line, and simultaneously generates the drive control signal ADS.

A line of display data DT (display data of 256 pixels) read from the display data storage unit 32 is buffered in the buffer 52 in the buffer area 52. The display data DT is, for example, data representing one of 256 gradations ("0/255" to "255/255") by 8 bits for one pixel.

The display data DT of one line of the buffer storage area, that is, the display data of 256 pixels, is supplied to the selector 53 via the subtractor 55 in the form of each pixel (8 bits). The selector 53 selects and outputs the target count value stored in the gradation table storage unit 54 based on the gradation value indicated by 8 bits.

For example, as shown in FIG. 12A, the gradation table stored in the gradation table storage unit 54 is a table structure in which 8-bit binary data is associated with a target count value. Further, the gradation value and the pulse width are also shown in FIG. 12A for reference, but it is not necessary to store them as actual table data. The gradation value is a number indicating 256 gradations indicated by 8-bit binary data "00000000" to "11111111" as "0/255" to "255/255". “0/255” is the black display gradation of the lowest brightness, and “255/255” is the white display gradation of the highest brightness. The pulse width is a time value indicating the number of bits of the pulse width of the data line drive signal controlled by the target count value, which becomes the length of time of the constant current output as the output signal of the anode driver.

In the present embodiment, although it is only an example, the primary count of the target count value is equivalent to 0.125 μs. For example, if the target count value is 1024, the pulse width is 128.0 μs.

The selector 53 reads and outputs the target count value in accordance with the display data expressed by the 8-bit binary data and referring to the gradation table. For example, in the case where the 8-bit display data is "11111101" (253/255 gradation), the output target count value = 1016 is output.

Further, such a target count value is a numerical value obtained by converting a gradation value as display data into a time value, and substantially corresponds to a numerical value which is a gradation value of the display data DT. The display data DT outputted by the selector 53 as the target count value is marked as display data DT' in Fig. 11 .

The display data DT' (target count value) output from the selector 53 is latched by the latch circuit 60.

The latch circuit 60 is provided with a plurality of latch circuits (256 latch circuits 60-1 to 60-256 in this embodiment) corresponding to respective pixels of one row. Then, the display data DT' (target count value) of each pixel of one line is latched by the corresponding latch circuit 60, respectively. Thus, the target count values of the respective pixels of one line are stored in the latch circuits 60-1 to 60-256, respectively.

The target count values latched by the latch circuits 60-1 to 60-256 are compared with the count values of the counter 61 in the comparison circuits 62-1 to 62-256, respectively, and the comparison result is obtained for each data line. The drive control signal ADS of the DL.

This operation will be described using FIG. 12B. The counter 61 repeatedly counts up to a predetermined upper limit value in accordance with a predetermined clock signal. The predetermined upper limit value is set to a value corresponding to one line of the scanning line SL. The output of the comparison circuit 62 falls to the L level at the reset timing of the count value. Then, when the count value reaches the target count value after the latch, the output of the comparison circuit 62 rises to the H level.

For example, when the target count value latched by a certain latch circuit 60-x is Dpw1, the drive control signal ADS1 is obtained as a comparison output of the comparison circuit 62-x. Further, when the target count value latched by the certain latch circuit 60-y is Dpw2, the drive control signal ADS2 is obtained as the comparison output of the comparison circuit 62-y.

As a result, the outputs of the comparison circuits 62-1 to 62-256 become the target count values latched by the latch circuits 60-1 to 60-256, that is, the pulses based on the time length of the display data gradation value.

Each of the comparison outputs described above is supplied to the anode driver 33 as the drive control signal ADS of each of the data lines DL1 to DL256. As illustrated in FIG. 3, the anode driver 33 outputs a constant current (data line drive signal) to each of the data lines DL1 to DL256 during the L level period of the pulse of each drive control signal ADS.

Thereby, a constant current output having a time length based on the gradation indicated by the display data DT is performed on each of the data lines DL.

The above is the operation of the basic timing controller 44 which does not consider the correction. In the case of the present embodiment, the correction value SH for each display data DT is calculated by the correction value generating unit 44a, and the correction value SH is subtracted from the respective display data DT in the subtractor 55, thereby performing Corrected.

The correction calculation initial value storage unit 66 in the correction value generation unit 44a stores the value of the reference luminance thr and the coefficients (coefP, coefM).

Further, the respective values of the reference luminance thr and the coefficients (coefP, coefM) can be rewritten in accordance with the rewrite command of the MPU 2. For example, in the case where the instruction decoder 42 acquires the rewrite instruction via the MPU interface 41 of FIG. 10, the instruction decoder 42 indicates to the timing controller 44 the rewriting of the reference luminance thr and the coefficients (coefP, coefM). At this time, the timing controller 44 updates the stored value of the correction calculation initial value storage unit 66.

The brightness correction amount calculation unit 65 in the correction value generation unit 44a of Fig. 11 calculates a correction value for the display data DT. For this purpose, the luminance correction amount calculation unit 65 reads the value of the reference luminance thr and the coefficients (coefP, coefM) from the correction calculation initial value storage unit 66, and also acquires the luminance setting value supplied from the current setting unit 45. Further, the luminance correction amount calculation unit 65 acquires 256 pieces of display data DT of one line from the buffer 52. Further, the luminance correction amount calculation portion 65 also sequentially acquires the display data DT of each pixel in one line supplied from the buffer 52 to the subtractor 55.

Then, the brightness correction amount calculation unit 65 calculates the correction value SH using these data, and supplies it to the subtractor 55.

In the subtracter 55, the correction value SH is subtracted from the display data DT, whereby the display data DT is corrected, and the corrected display data DT is supplied to the selector 53.

The correction processing by the luminance correction amount calculation unit 65 and the subtractor 55 will be described in detail with reference to Fig. 13 .

In step S100, the brightness correction amount calculation unit 65 reads the reference brightness thr, and compares the reference brightness thr with the brightness setting value transmitted from the current generation unit 33a in step S101. In this case, it is determined whether the brightness setting value > the reference brightness thr or the brightness setting value <the reference brightness thr or the brightness setting value = the reference brightness thr?

In the case of the brightness setting value > the reference brightness thr, the brightness correction amount is calculated The unit 65 acquires the coefficient coefP from the correction calculation initial value storage unit 66 in step S102, and obtains the non-lighting rate (=1-lighting rate) based on the 256 pieces of display data DT of one line in step S103. The lighting rate is obtained using the calculation described in FIG.

Then, in step S106, the brightness correction amount calculation unit 65 calculates the correction value SH. In this case, the correction value SH is obtained using the equation of FIG. 8E.

Then, in step S107, the correction value SH is subtracted from the display data DT in the subtractor 55, thereby correcting the display data DT.

Further, the steps S106, S107 are shown in a simplified manner, but actually, steps S106 and S107 are performed 256 times for one line. That is, each display data DT to be supplied to the selector 53 is calculated using the calculation of Fig. 8E using the display data DT, and the correction value SH is subtracted from the display data DT.

Then, the correction in this case becomes the correction of the brightness of the reduced area AR2 explained in FIGS. 7A and 7B.

When it is determined in step S101 that the brightness setting value <reference brightness thr, the brightness correction amount calculation unit 65 acquires the coefficient coefM from the correction calculation initial value storage unit 66 in step S104, and in step S105, according to one line of 256 The display data DT is calculated using the calculation described in FIG.

Then, in step S106, the brightness correction amount calculation unit 65 calculates the correction value SH. In this case, the correction value SH is obtained using the equation of FIG. 8F.

Then, in step S107, the correction value SH is subtracted from the display data DT in the subtractor 55, thereby correcting the display data DT.

In this case, steps S106 and S107 are also performed 256 times for one line. That is, each display data DT to be supplied to the selector 53 is calculated using the operation of Fig. 8F using the display data DT, and the correction value SH is subtracted from the display data DT.

Then, the correction in this case is the correction of the brightness of the reduced area AR1 described in FIGS. 7C and 7D.

When it is determined in step S101 that the brightness setting value = the reference brightness thr, no correction is necessary. Here, the correction value SH=0 is made in step S108. The subtracter 55 in step S107 outputs the input display data DT which is left as it is.

As described above, in the case where the luminance setting value is higher than the reference luminance thr, the correction value SH is obtained using the equation of FIG. 8E. That is, the display data DT is multiplied by the non-lighting rate (=1-lighting rate) and the correction coefficient hkp.

Further, when the brightness setting value is lower than the reference brightness thr, the correction value SH is obtained using the equation of FIG. 8F. That is, the display data DT is multiplied by the lighting rate and the correction coefficient hkm.

Then, the display data DT is corrected by subtracting the correction value SH, and the corrected display data DT is supplied to the selector 53. Then, a drive control signal ADS is generated based on the corrected display data DT.

As a result, the data line drive signal output to the data line DL becomes a constant current signal having a length of time based on the corrected display data DT.

Here, a specific example of the correction coefficients hkp and hkm is shown in FIG.

As shown in FIG. 14A, the reference luminance thr=60, the coefficient coefP=1/50, the coefficient coefM=-1/70, and the value range (RAN)=2.

The range of values is centered on the reference luminance thr and does not need to be corrected. In this case, the correction is not required in the range of "58" to "62" with the reference luminance thr=60 (cd/m2) as the center. The range of the brightness "58" to "62" is a case where the brightness unevenness is hardly noticeable. Further, in the case where the value range (RAN) = 2, in the case of the processing of Fig. 13, when the luminance setting value is in the range of "58" to "62", it is determined in step S101 that the luminance setting value = Reference brightness thr.

The correction coefficients hkp, hkm are as shown in Figs. 14B and 14C. 14C shows the vertical axis as the correction coefficient and the horizontal axis as the brightness setting value.

The correction coefficient hkp is equal to the difference between the brightness setting value Lum and the reference brightness thr (=60) (but because the value range = 2, so thr=62) multiplied by the coefficient coefP, so that the higher the brightness setting value, the correction coefficient The bigger the hkp.

The formula of FIG. 8E is such that the correction coefficient hkp and the non-lighting rate (=1-lighting rate) are multiplied by the display data DT, thereby obtaining a difference between the brightness setting value and the reference brightness thr and each line. By correcting the correction value of the non-lighting rate (=1-lighting rate) from the display data DT, it is possible to eliminate or reduce the brightness unevenness as shown in FIG. 7B, for example, to make the brightness and the area of the area AR2 The brightness of AR1 is the same.

The correction coefficient hkm is equal to the difference between the luminance set value Lum and the reference luminance thr (=60) (but because of the range=2, so thr=58) multiplied by the coefficient coefM, so that the lower the luminance setting value, the correction coefficient The bigger the hkp.

The formula of Fig. 8F is such that the correction coefficient hkm and the lighting rate are multiplied by the display data DT, so that a correction value reflecting the difference between the brightness setting value and the reference brightness thr and the lighting rate per line is obtained. By subtracting the correction value from the display data DT, the brightness unevenness can be eliminated or reduced as shown in FIG. 7D, for example. Even so that the brightness of the area AR1 is equal to the brightness of the area AR2.

<5. Second embodiment>

The second embodiment will be described with reference to Fig. 15 . In FIG. 15 , the same portions as those in FIG. 11 are denoted by the same reference numerals, and their description is omitted.

Fig. 15 shows another configuration example of the timing controller 44. The correction of the display data DT' (target count value) is different from the case of Fig. 11 described above. Therefore, the subtractor 55 is provided on the output side of the selector 53.

The brightness correction amount calculation unit 65 in the correction value generation unit 44a of Fig. 15 calculates a correction value for the display data DT'. Therefore, the luminance correction amount calculation unit 65 reads the values of the reference luminance thr and the coefficients (coefP, coefM) from the correction calculation initial value storage unit 66, and acquires the luminance setting values supplied from the current setting unit 45. Further, the luminance correction amount calculation unit 65 acquires 256 pieces of display data DT of one line from the buffer 52. Further, the luminance correction amount calculation portion 65 also sequentially acquires the display data DT' (target count value) of each pixel in one line supplied from the selector 53 to the subtractor 55.

Then, the brightness correction amount calculation unit 65 calculates the correction value SH using these data, and supplies it to the subtractor 55.

In the subtracter 55, the correction value SH is subtracted from the display data DT', thereby correcting the display data DT', and supplying the corrected display data DT' to the latch circuit 60.

The correction processing by the luminance correction amount calculation unit 65 and the subtractor 55 in this case is shown in FIG.

In step S200, the brightness correction amount calculation unit 65 reads the reference brightness thr, and in step S201, sets the reference brightness thr and the slave current generation unit 33a. The delivered brightness settings are compared. In this case, it is determined whether the brightness setting value > the reference brightness thr or the brightness setting value <the reference brightness thr or the brightness setting value = the reference brightness thr?

In the case of the luminance setting value > the reference luminance thr, the luminance correction amount calculation unit 65 acquires the coefficient coefP from the correction calculation initial value storage unit 66 in step S202, and obtains the 256 pieces of display data DT in one row in step S203. Non-lighting rate (=1-lighting rate).

Then, in step S206, the brightness correction amount calculation unit 65 calculates the correction value SH. In this case, the correction value SH is obtained using the equation of Fig. 8E, but the "display data" in the formula of Fig. 8E becomes the display data DT'. That is, the correction value of the target count value is obtained.

Then, in step S207, the correction value SH is subtracted from the display data DT' in the subtractor 55, thereby correcting the display data DT'.

Actually, steps S206 and S207 are performed 256 times for one line. That is, for each display data DT' output from the selector 53, the correction value SH is calculated using the operation of Fig. 8E using the display data DT', and the correction value SH is subtracted from the display data DT'. .

Then, the correction in this case becomes the correction of the brightness of the reduced area AR2 explained in FIGS. 7A and 7B.

When it is determined in step S201 that the brightness setting value <reference brightness thr, the brightness correction amount calculation unit 65 acquires the coefficient coefM from the correction calculation initial value storage unit 66 in step S204, and in step S205, according to one line of 256 The display data DT finds the lighting rate.

Then, in step S206, the brightness correction amount calculation unit 65 calculates the repair Positive value SH. In this case, the correction value SH is obtained using the equation of Fig. 8F, but the "display data" in the formula of Fig. 8F becomes the display data DT'. That is, the correction value of the target count value is obtained.

Then, in step S207, the correction value SH is subtracted from the display data DT' in the subtractor 55, thereby correcting the display data DT'.

In this case, steps S206 and S207 are also performed 256 times for one line. That is, for each display data DT' output from the selector 53, the correction value SH is calculated using the operation of Fig. 8F using the display data DT', and the correction value SH is subtracted from the display data DT'. .

Then, the correction in this case is the correction of the brightness of the reduced area AR1 described in FIGS. 7C and 7D.

When it is determined in step S201 that the brightness setting value = the reference brightness thr, no correction is necessary. Here, the correction value SH=0 is made in step S208. The subtracter 55 in step S207 outputs the input display data DT' which remains as it is.

By the above processing, correction of display data for reducing or eliminating luminance unevenness is also realized in the same manner as in the first embodiment.

<6. Third embodiment>

The third embodiment will be described with reference to Fig. 17 . The third embodiment is a mode of transmitting to the controller IC 20 after the display data DT is corrected on the MPU 2 side.

Fig. 17A shows the configuration of the timing controller 44. In this case, since it is not necessary to perform correction in the timing controller 44, the correction value generating unit 44a and the subtractor 55 are not provided. Each part performs its work as explained previously, and each Drive control signal ADS.

On the other hand, in this case, the correction value generating unit 2a and the display data correcting unit 2b are provided in the MPU 2 as shown in Fig. 17B.

Then, the correction value generating unit 2a performs the same processing as steps S100 to S106 of FIG. 13, and the display data correcting unit 2b may perform the same processing as that of step S107.

That is, the same correction is performed on the display data DT at the stage before the MPU 2 transmits to the controller IC 20, and substantially the same correction as in the first embodiment.

<7. Summary and Modifications>

In the above-described embodiment, the controller IC (display driving device) that drives the data line DL of the display unit 10 in accordance with the gradation value of the corresponding pixel includes a current setting unit 45 that controls to drive each data. The data line drive signal of the line DL is a constant current signal based on the set brightness; the correction value generation unit 44a generates a correction value SH of the display data DT (or DT'), and the drive control signal generation unit 44b displays the display data DT (or DT). ') The correction process is performed using the correction value SH generated by the correction value generation unit 44a, and based on the display data after the correction process, the drive control signal ADS in which the drive period of the data line drive signal is specified is generated.

Then, when the set brightness is lower than the reference brightness thr, the correction value generating unit 44a generates the correction value SH using the difference between the set brightness and the reference brightness thr and the lighting rate in the display data unit corresponding to one line of scanning line period. In the case where the set brightness is higher than the reference brightness thr, the difference between the set brightness and the reference brightness thr, and the non-lighting rate in the display data unit (=1-) are used. The lighting rate) generates a correction value SH.

By performing such correction, it is possible to eliminate or reduce luminance unevenness on the display, and it is possible to improve display quality.

That is, in the case where the set luminance is higher than the reference luminance thr, the lower the lighting rate is, and the larger the difference between the set luminance and the reference luminance is, the higher the luminance of the lighting pixel is. Further, in the case where the set luminance is lower than the reference luminance thr, the lower the lighting rate is, and the larger the difference between the set luminance and the reference luminance is, the lower the luminance of the lighting pixel is. By correcting the display data DT (or DT') which should cancel such a change in luminance, it is possible to eliminate or reduce the luminance unevenness of the screen in the case where the luminance change occurs.

Further, the correction processing is corrected in the direction in which the driving period of the data line driving signal is shortened as explained in FIGS. 7A and 7C. Specifically, it is a correction in which the correction value SH is subtracted from the display data DT (or DT') in the subtractor 55.

By such correction, it is possible to perform correction without increasing the maximum value of the gradation value (data line driving period), and it is very convenient to manufacture without requiring a large design change.

Further, since the brightness of the displayed character or the like is zero (gradation "0/255"), the brightness correction in the direction of reducing the brightness does not affect the brightness of the display content such as characters.

Further, in the embodiment, as shown in FIG. 9, the lighting rate is set, the gradation values indicated by the respective display data in the display data unit are accumulated, and the integrated value is divided by the gradation number, and the obtained The value is divided by the number of display data in the display data unit (one row). Non-lighting rate press (1-lighting rate) To find out.

That is, instead of setting the lighting rate to the ratio of the number of lighting pixels of one line, the value of the gradation of each lighting pixel is also considered. This makes it possible to set more correct parameters for correction and to improve the correction accuracy.

Further, since it is not necessary to perform processing for calculating the lighting pixels/non-lighting pixels, only the integrated value of the display data DT is divided by the number of gradations and the number of display data, so that the calculation processing load of the lighting rate can be reduced.

However, it is also possible to obtain a certain degree of correction effect by setting the lighting rate to only the ratio of the luminescent pixels (pixels of "1/255" gradation or more).

Further, in the first and third embodiments, the display data DT, that is, the display data DT which is a predetermined number of digit gradation values, is used as a target to generate a correction value, and the display data DT is subjected to correction processing using a correction value. .

By performing correction value generation and correction on the display data DT at the stage in which the gradation value is expressed by a predetermined number of bits, it is possible to select various stages of correction. For example, it may be performed in the display driving phase as in the first embodiment, or may be performed on the MPU 2 side as in the third embodiment. In addition to this, it is conceivable to correct the stage after the display data storage unit 32 is acquired or before the display data storage unit 32 is written.

Further, in the second embodiment, the input predetermined bit number gradation value (display data DT) is converted into a target count value corresponding to the driving period, and the display data DT' in this state is used as an object to generate a correction value. Correction processing using the correction value is performed on the display data DT'.

The correction value generation and repair are performed by using the display data DT' in a state in which the gradation value has been converted into the target count value corresponding to the driving period. Positive, it is possible to correct at a finer gradation resolution than the gradation resolution of the display data before conversion. This is because, in the case where the display data DT is 256 gradations, the target count value is set to at least 256 count values. For example, in the example of Fig. 12A, the target count value (display data DT') is 0 to 1024, the resolution of the gradation is increased, and finer correction than the correction of the display data DT can be performed.

Further, the reference luminance thr may have a width (value range) as shown in the example of FIG. 14 in addition to a specific value.

This is because, when the brightness setting value is a certain value as in the brightness setting value 60 of FIG. 4, the brightness unevenness is minimized, and the degree of brightness unevenness is not substantially recognized before and after the reference brightness thr. In this case, there is no need to make corrections.

Further, the correction value SH is calculated based on the display data DT (or DT'), the lighting rate (or the non-lighting rate), the difference between the set brightness and the reference brightness thr, and the coefficients (coefP, coefM).

In this way, it is possible to appropriately reduce or eliminate luminance unevenness in accordance with various display contents in accordance with an arbitrary display pattern.

Further, the reference luminance thr and the coefficients (coefP, coefM) stored in the calculation initial value storage unit 66 can be rewritten by the MPU 2. Since it is assumed that the reference luminance thr or an appropriate coefficient varies for each method or each individual of the display device 1, it is assumed that these values can be rewritten. By appropriately setting the reference luminance thr or the coefficients (coefP, coefM), it is possible to maximize the effect of improving the luminance unevenness regardless of the method or individual difference of the display device 1.

Moreover, this also applies to the versatility of the components of the controller IC 20.

Further, for example, the correction may be performed using only the lighting rate without using the non-lighting rate. However, in this case, it is necessary to judge which of the areas AR1, AR2 shown in FIGS. 5 and 7 is actually to be corrected.

For example, after the comparison between the brightness setting value and the reference brightness thr is performed in step S101 of FIG. 13, before the correction of the display data in step S107, it is necessary to determine whether the range to be actually corrected is the area AR1 or the area AR2.

On the other hand, in the present embodiment, the lighting rate and the non-lighting rate are separately distinguished from the correction value calculation based on the result of step S101, and therefore it is not necessary to determine whether the range to be actually corrected is the area AR1 or the area AR2 as described above. Processing. That is, it is not necessary to consider whether the selected line to be corrected is the area AR1 or the area AR2, and which line in the display unit 10 can perform the calculation of the correction processing in accordance with a formula.

Also in this embodiment, the reduction of the correction processing load is achieved based on this point.

Further, as described above, the lighting rate is obtained by dividing the integrated value of the display data DT by the number of gradations and the number of display data, thereby reducing the lighting rate and the non-lighting rate (=1-lighting rate). This also greatly contributes to the reduction of the processing load of the correction process.

By reducing the processing load for correction in this way, the present embodiment is also applicable to a case where correction processing is performed for each line while performing sequential scanning of lines.

The embodiment has been described above, but the display of the present invention is not Embodiments of the device or display drive device are defined, and various modifications are conceivable.

For example, as an example of the display driving device, the controller IC 20 shown in FIG. 1 incorporates the anode driver 33, but the anode driver 33 may be separately provided.

Further, two drivers of the anode driver 33 and the cathode driver 21 may be incorporated in the controller IC 20.

Further, when the controller IC 20 is used as a dedicated component of a specific display panel, the correction calculation initial value storage unit 66 may use a ROM area. That is, the case where the reference luminance thr and the coefficients (coefP, coefM) are not rewritten is not required.

Further, although the current value of the data line drive signal as the constant current signal is variably controlled according to the set brightness, although the overall brightness is adjusted, it is also conceivable to adjust the pulse width of the data line drive signal in accordance with the set brightness. structure.

Furthermore, the present invention is applicable not only to display devices using OLEDs, but also to other types of display devices. It is particularly suitable for display devices using current-driven self-luminous elements.

S100~S108‧‧‧Steps

Claims (9)

A display driving device, wherein the display portion is respectively configured with a plurality of data lines and scan lines, the data lines being connected to a plurality of pixels arranged in a column direction, the scan lines being connected to a plurality of pixels arranged in a row direction, A pixel is formed at each intersection of the data line and the scan line, and the data line is driven by the display unit according to a gray value of a corresponding pixel. The display driving device is characterized in that: the current setting is included The control unit is configured to cause the data line drive signal for driving the respective data lines to be a constant current signal based on the set brightness, the correction value generation unit to generate a correction value for the display data, and the drive control signal generation unit to use the display data. The correction processing of the correction value generated by the correction value generating unit generates a driving control signal for driving a predetermined data line driving signal based on the display data after the correction processing, and the correction value generating unit sets the brightness When the brightness is lower than the reference brightness, the difference between the set brightness and the reference brightness is used, and the scan is equivalent to one line a lighting rate in the display data unit, generating a correction value, wherein, when the set brightness is higher than the reference brightness, using a difference between the set brightness and the reference brightness, and in the display data unit The non-lighting rate generates a correction value. The display driving device according to claim 1, characterized in that, as the correction processing, the drive control signal generating unit performs data line driving The correction of the direction in which the driving period of the signal becomes shorter. The display driving device according to claim 1, wherein the lighting rate is obtained by integrating the gradation values indicated by the respective display data in the display data unit to obtain an integrated value, and dividing the accumulated value The value obtained by dividing the obtained value by the number of display data in the display data unit by the number of gray scales, the non-lighting rate being 1 minus the value of the lighting rate. The display drive device according to claim 1, wherein the correction value generation unit generates a correction value by using the input display data as a predetermined number of digit gradation values, and the drive control signal generation unit pairs the input. As the display data of the predetermined number of bits gradation value, correction processing using the correction value generated by the correction value generating unit is performed. The display driving device according to claim 1, wherein the reference luminance is luminance that does not cause a luminance change between a row in which the lighting pixel and the non-lighting pixel are mixed and a row in which only the lighting pixel is generated. A display driving device according to claim 1, wherein the reference luminance has a width. The display driving device according to claim 1, wherein the correction value generating unit generates a correction value by using the display data as an object, and the display data converts the input predetermined number of bit gradation values into the equivalent The display data in the state of the count value of the driving period, the drive control signal generating unit uses the display data in a state in which the input predetermined number of digit gradation values are converted into the count value corresponding to the driving period. The repair generated by the correction value generating unit Positive correction processing. A display device comprising: a display portion respectively configured with a plurality of data lines and scan lines, the data lines being connected to a plurality of pixels arranged in a column direction, the scan lines being connected to a plurality of pixels arranged in a row direction a pixel corresponding to each intersection of the data line and the scan line; a display driving unit that drives the data line according to a gray value of a corresponding pixel; and a scan line driving unit that applies the scan line The scan signal is characterized in that the display drive unit includes a current setting unit that controls a data line drive signal for driving the respective data lines to be a constant current signal based on a set brightness, and a correction value generation unit that generates display data. The correction value and the drive control signal generation unit perform a correction process using the correction value generated by the correction value generation unit on the display data, and generate a drive period of the predetermined data line drive signal based on the display data after the correction process. a drive control signal, wherein the correction value generation unit uses the setting when the set brightness is lower than the reference brightness a difference between the brightness and the reference brightness, and a lighting rate corresponding to a display data unit of the scan line, generating a correction value, and when the set brightness is higher than the reference brightness, using the setting A correction value is generated by a difference between the brightness and the reference brightness and a non-lighting rate in the display data unit. A display data correction method for generating a data line driving signal for driving the respective data lines to a display unit as a constant current signal based on a set brightness, and generating the predetermined period during driving based on a corresponding pixel gradation value a driving control signal for driving the data line driving signal, wherein the display portion is respectively configured with a plurality of data lines and scan lines, the data lines being connected to a plurality of pixels arranged in a column direction, the scan lines being connected to the line a plurality of pixels arranged in a direction, wherein pixels are formed corresponding to respective intersections of the data line and the scan line, and the display data is corrected by using the setting when the set brightness is lower than the reference brightness a difference between the brightness and the reference brightness, and a lighting rate in a display data unit corresponding to one line of the scan line, generating a correction value of the display data, and when the set brightness is higher than the reference brightness, using a difference between the set brightness and the reference brightness and a non-lighting rate in the display data unit, and a correction value of the display data is generated, and the use value is used. The correction value to the display data correction processing.