KR20240076049A - Method and system for optical compensation, and display driver with optical compensation function - Google Patents

Abstract

The present invention discloses a display panel optical compensation method and system for luminance compensation for a display panel, and a display driver having an optical compensation function. The optical compensation according to the present invention can quickly and easily set compensation information corresponding to the target luminance for optical compensation of the display panel by using a plurality of luminance levels for each of the plurality of image gray levels prepared in advance for the measurement results of the display panel.

Description

Optical compensation method and system for display panel, and display driver having optical compensation function {METHOD AND SYSTEM FOR OPTICAL COMPENSATION, AND DISPLAY DRIVER WITH OPTICAL COMPENSATION FUNCTION}

The present invention relates to optical compensation of a display panel, and more specifically, to a method and system for optical compensation of a display panel for luminance compensation for a display panel, and to a display driver having an optical compensation function.

A display panel, such as an LCD, has subpixels arranged in a matrix, and can display a screen by emitting light from selected subpixels. Sub-pixels may include red pixels, green pixels, blue pixels, and white pixels.

When displaying white in a display panel, the luminance of white may be determined by the emission ratio of red pixels, green pixels, and blue pixels.

Mass-produced display panels cannot achieve the desired luminance corresponding to the reference gamma voltage. Therefore, optical compensation is required to optically measure the luminance of the display panel and compensate for the luminance with the measured result.

As a representative example of the optical compensation, white compensation is required for the display panel.

Typically, a display panel can adjust the brightness of a pixel using a complex algorithm that simultaneously adjusts the gains of red, green, and blue. The gains and luminance of red, green, and blue have different increases for each gray. Therefore, it is difficult to predict the common amount of change in luminance to converge to the target luminance value.

Therefore, for the above-described white compensation, a target luminance convergence process that repeats measurement while changing the data voltage for each subpixel is generally required.

However, the above-described target luminance convergence process requires a large number of repeated loops, and an individual target luminance convergence process must be applied to each subpixel.

Therefore, there is a problem that optical compensation of the display panel takes a lot of time.

In addition, the time required to test all display panels that are mass-produced may increase due to the above-mentioned problems, which may cause secondary problems in the mass production of the display panel.

The purpose of the present invention is to provide a method and system for optical compensation of a display panel that can quickly and easily set compensation information corresponding to the target luminance for optical compensation of the display panel.

The present invention provides a display driver with an optical compensation function that stores compensation information for target luminance for optical compensation of a display panel and provides a gamma voltage for converting display data to analog using the compensation information. has another purpose.

The optical compensation method of the display panel of the present invention stores a test lookup table, wherein the test lookup table determines test sub-gray values for subpixels for each test luminance level corresponding to a reference gamma curve for preset test image gray levels. Step including levels: generating a measured luminance level and a measured sub-gray level by measuring the luminance of the display panel using first test sub-gray levels corresponding to the selected first test image gray level; selecting second test sub-gray levels of a second test image gray level corresponding to the measured sub-gray levels from the test lookup table; and generating compensation information by correcting the second test sub-gray levels with a proportional relationship between the measured luminance level and the first test image gray level.

The optical compensation system of the display panel of the present invention includes test information that stores a test lookup table containing test sub-gray levels for sub-pixels for each test luminance level corresponding to a reference gamma curve for preset test image gray levels. storage unit; a test execution unit providing display data corresponding to first test sub-gray levels corresponding to the first test image gray level selected from the test lookup table to the display panel; Receives a measured luminance level and measured sub-gray levels corresponding to a result of the luminance measurement of the display panel, and a second test sub-gray level of a second test image gray level corresponding to the measured sub-gray levels in the test lookup table. a compensation information generator for generating compensation information by selecting sub-gray levels and correcting the second test sub-gray levels with a proportional relationship between the measured luminance level and the first test image gray level; and a compensation information storage unit that stores a compensation lookup table that stores the corrected sub-gray levels of the second test sub-gray levels with respect to the second test image gray level.

In addition, the display driver of the present invention includes a compensation information storage unit that stores sub-gray levels for sub-pixels for white compensation for each of a plurality of preset image gray levels as compensation information; a compensation unit providing compensation control signals corresponding to sub-gray levels for each of the plurality of image gray levels corresponding to a specific sub-pixel; a gamma voltage provider providing gamma voltages for expressing luminance of the specific subpixel; and a digital-to-analog converter that converts display data for the specific sub-pixel into an analog signal using the gamma voltages, wherein the gamma voltage provider converts the levels of the gamma voltages to a preset reference gamma curve. Characterized by changing from 1 levels to second levels corresponding to the gamma curve changed by the compensation control signals for optical compensation.

The present invention has the advantage of quickly and easily setting compensation information corresponding to the target luminance for optical compensation of the display panel by compensating the measured results of the display panel using a plurality of luminance levels for each of the plurality of image gray levels prepared in advance. .

Therefore, the present invention has the advantage of reducing the time required for optical compensation of a display panel and reducing the time required to test all mass-produced display panels.

Additionally, the present invention can provide a display driver with an optical compensation function that provides gamma voltages to subpixels using compensation information stored for optical compensation. Therefore, the display panel can be driven with an analog signal in which display data is converted to correspond to optically compensated gamma voltages.

1 is a block diagram showing a preferred embodiment of an optical compensation system for a display panel of the present invention.
Figure 2 is a flowchart showing a preferred embodiment of the optical compensation method for a display panel of the present invention.
3 is a graph illustrating a reference gamma curve.
4 is a graph illustrating a gamma curve corresponding to measurement results.
Figure 5 is a diagram illustrating a test lookup table.
6 is a diagram illustrating a compensation lookup table.
Figure 7 is a block diagram illustrating a partial configuration of the compensation information generation unit.
8 is a diagram illustrating a display system.
9 is a block diagram showing an embodiment of a display driver with optical functions of the present invention.

The present invention illustrates an embodiment for optical compensation of a display panel. In an embodiment of the present invention, the display panel may be an LCD panel.

In the present invention, optical compensation of a display panel means optically measuring the display panel and generating compensation information that can compensate the luminance of the display panel to the target luminance as a result of the measurement.

Mass-produced display panels require optical compensation during the testing process. For optical compensation, the display panel is tested to generate compensation information that can indicate the target luminance.

An embodiment of the present invention discloses an optical compensation system and an optical compensation method for obtaining compensation information through the above-described test. Compensation information obtained by an embodiment of the present invention can be applied to the display driver, and the display driver can drive the display panel to emit light at the correct luminance corresponding to the display data by using the compensation information.

The present invention may include a display driver that applies the above-described compensation information as an embodiment. In this case, the display driver can be understood as having an optical compensation function, and can compensate the luminance of the display panel to reach the target luminance using compensation information.

By way of example. White luminance corresponding to gamma 2.2 can be set as the target luminance. Here, gamma 2.2 (G2.2) can be understood as corresponding to the exponent of the expression of the gamma curve.

A pixel may include subpixels that emit white, red, green, and blue. When expressing white, the luminance of white can be determined by the luminance ratio of red, green, and blue.

Embodiments of the present invention may be understood as performing optical compensation for compensation of white luminance, and in the description of the embodiments of the present invention below, subpixels may be understood to correspond to red, green, and blue.

The optical compensation method of the display panel of the present invention can be implemented by the optical compensation system of FIG. 1.

Referring to FIG. 1 , the optical compensation system 100 may be configured to provide display data DAT to the display panel DP and receive luminance measurement results from a luminance meter TW.

The optical compensation system 100 may be configured to include a test information storage unit 110, a test execution unit 112, a compensation information generation unit 114, and a compensation information storage unit 116.

The optical compensation system 100 of FIG. 1 described above can perform the optical compensation method of FIG. 2. Embodiments of the present invention will be described in terms of configuration and operation with reference to FIGS. 1 and 2.

The test information storage unit 110 may store a test lookup table as test information. The test lookup table can be understood with reference to FIG. 5 described later. That is, the test lookup table may include test sub-gray levels for sub-pixels (R, G, B) for each test luminance level (TLV) corresponding to the reference gamma curve for preset test image gray levels (TIGL). You can. Illustratively, the test lookup table registers test sub-gray levels for sub-pixels (R, G, B) corresponding to a plurality of test luminance levels (TLV) for each test image gray level (TIGL) ( REG) can be stored separately.

In the test lookup table of the test information storage unit 110, a plurality of test image gray levels (TIGL) can be understood as selected by the producer to express the gamma curve, and a plurality of test luminance levels (TLV) are also It can be understood that what can be expressed in the corresponding test image gray level (TIGL) has been selected by the producer.

By way of example, the test lookup table of the test information storage unit 110 may be understood as corresponding to gamma 2.2 (G2.2), and the gamma curve of gamma 2.2 is shown as a reference gamma curve for an embodiment of the present invention. It can be illustrated as in 3. FIG. 3 may be understood as displaying luminance for each gray level, and gray levels T0 to T7 may be understood to correspond to test image gray levels (TIGL). In the case of a gamma scale of 256 grayscale levels, T0 corresponds to the lowest gamma grayscale level, 0 level, or “G0,” and T7 corresponds to the maximum gamma grayscale level, 255 level, or “G255.”

The test execution unit 112 may sequentially select test image gray levels (TIGL) from the test lookup table of the test information storage unit 110 (S10).

The test execution unit 12 may provide display data DAT corresponding to test sub-gray levels TSET (R1, G1, B1) corresponding to the selected test image gray level (TIGL) to the display panel (RP). At this time, test sub-gray levels TSET (R1, G1, B1) corresponding to one test luminance level (TLV) selected among the test luminance levels (TLV) corresponding to the test image gray level (TIGL) may be selected. As an example, the test execution unit 12 may select test sub-gray levels TSET (255, 255, 255) corresponding to test luminance level (TLV) 500 among the test luminance levels of G255 of the test image gray level (TIGL). .

The test execution unit 112 provides display data DAT corresponding to the selected test sub-gray levels TSET (255, 255, 255) to the display panel DP, and the display panel DP corresponds to the test sub-gray levels TSET (255, 255, 255). luminance can be displayed. At this time, the display data (DAT) may be equally provided to all pixels of the display panel (DP), and all pixels of the display panel (DP) may display luminance corresponding to the test sub-gray levels TSET (255, 255, 255). there is.

The luminance of the display panel (DP) can be measured by a luminance meter (TW) (S12). A luminance meter (TW) may be configured to measure luminance by taking an image or measuring illuminance.

The luminance meter (TW) may provide a measured luminance level (MLV) corresponding to a measurement result and measured sub-gray levels MSET (R2, G2, B2) of subpixels. As shown in FIG. 4, the luminance meter (TW) measures a measured luminance level (MLV) with a changed luminance such as gamma 1.9 (G1.9) or gamma 2.6 (G2.6) and measured sub-gray levels MSET (R2, G2, B2) can be provided.

The compensation information generator 114 may receive the measured luminance level (MLV) corresponding to the luminance measurement result and the measured sub-gray levels MSET (R2, G2, B2) of the subpixels from the luminance meter (TW) (S14) ). In addition, the compensation information generation unit 114 is configured to receive the test luminance level (TLV) from the test execution unit 112 and to query the test lookup table of the test information storage unit 110.

The correction information generator 114 generates a test image of the test lookup table corresponding to the measured luminance level MLV and the measured sub-gray levels MSET (R2, G2, B2) of the subpixels generated by measuring the luminance of the display panel DP. The test sub-gray levels SSET (R3, G3, B3) of gray level TIGL can be obtained (S16). The correction information generator 114 selects test sub-gray levels that are the same as or closest to the measurement sub-gray levels MSET (R2, G3, B2) among the test sub-gray levels TSET (R1, G1, B1) of the test lookup table. SSET (R3, G3, B3) can be selected.

Referring to FIG. 5, the test sub-gray levels “250, 248, 250” are the same as or closest to the measurement sub-gray levels MSET (R2, G3, B2) or the test sub-gray levels SSET (R3, G3, B3). ), and the test sub-gray levels “250, 248, 250” correspond to test luminance level (TLV) 489 of test image gray level (TIGL) G253.

The compensation information generator 114 uses the proportional relationship between the measured luminance level MLV and the test sub-gray levels TSET (R1, G1, B1) selected for testing by the test execution unit 112 to determine the test sub-gray levels SSET ( By correcting R3, G3, B3), corrected sub-gray levels NSET (R4, G4, B4) can be generated (S18).

More specifically, the compensation information generator 114 generates a ratio LVR between the measured luminance level MLV and the test image gray level TLV of the test sub-gray levels TSET (R1, G1, B1) selected for testing by the test execution unit 112. is obtained using the formula below.

LVR=MLV/TLV

For the purpose of explaining the embodiment of the present invention, assuming that the measured luminance level MLV is 510, the test image gray level TLV of the test sub-gray levels TSET (R1, G1, B1) selected for testing by the test execution unit 112 is Since it is 500, the ratio LVR can be understood as 1.02.

When the ratio LVR is obtained as described above, the compensation information generator 114 corrects the test sub-gray levels SSET (R3, G3, B3) using the ratio LVR as shown in the following equation to produce the corrected sub-gray levels NSET (R4, G4, B4) can be obtained.

NSET(R4, G4, B4)=SSET(R3, G3, B3)*LVR

From the above, the ratio LVR is 1.02 and the test sub-gray levels SSET(R3, G3, B3) are "250, 248, 250", so multiplying each test sub-gray level by LVR gives the corrected sub-gray levels NSET(R4, G4, B4) can be obtained as "255, 252, 255".

The compensation information generator 114 may store the correction sub-gray levels NSET (R4, G4, B4) as the test image gray level of the test sub-gray levels SSET (R3, G3, B3). , the luminance level can be set to the test luminance level TLV corresponding to the test sub-gray levels TSET (R1, G1, B1).

That is, the compensation information may be set to the corrected sub-gray levels “255, 252, 255” of the luminance level 500 corresponding to the image gray level G253.

The compensation information storage unit 116 stores the correction sub-gray levels NSET (R4, G4, B4) in which the test sub-gray levels SSET (R3, G3, B3) have been corrected. ) of the test image gray level can be saved (S20).

The compensation information storage unit 116 may store the above-described compensation information as a compensation lookup table as shown in FIG. 6. Referring to FIG. 6, the compensation lookup table is set to store the compensation sub-gray levels NSET (R4, G4, B4) corresponding to the image gray level (NIGL) and the corresponding luminance level (NLV) for each register (REG). It can be. As an example, the compensation information storage unit 116 may store the corrected sub-gray levels “255, 252, 255” of the luminance level (NLV) 500 corresponding to the image gray level (NIGL) G253 in the compensation lookup table.

As a result, the embodiment of the present invention corresponds to the image gray level (NIGL) G253 as a result of testing the test sub-gray levels (R1, G1, B1) corresponding to gray level 500 of the test image gray level (TIGL) G255. The corrected sub-gray levels (R4, G4, B4) “255, 252, 255” can be stored as luminance level (NLV) 500.

An embodiment of the present invention can generate a compensation lookup table with compensation information as shown in FIG. 6 by performing the above-described test on a plurality of test image gray levels (TILG).

The embodiment of the present invention can be understood as obtaining an image gray level (NIGL) and correction sub-gray levels NSET (R4, G4, B4) that can maintain the test luminance level (TLV) for the display panel (DP). . In other words, the embodiment of the present invention can be understood as generating correction information that adjusts measurement results that differ from gamma 2.2 (G2.2) to approximate gamma 2.2 (G2.2).

As described above, the embodiment of the present invention compensates for the measurement results of the display panel DP using a plurality of luminance levels for each of the plurality of image gray levels prepared in advance, thereby achieving a target luminance for optical compensation of the display panel. You can set compensation information quickly and easily.

Therefore, embodiments of the present invention can reduce the time required for optical compensation of a display panel and reduce the time required to test all mass-produced display panels.

Meanwhile, the correction information obtained as described above may be applied to the display driver, and the display driver may be configured to control gamma voltages using the correction information in order to compensate for the optical characteristics of the display panel DP.

This will be described in detail with reference to FIGS. 8 and 9.

A display system for driving a display panel (DP) can be briefly illustrated as including a timing controller (TCON) and a display driver (DIC). A driver that provides a gate signal for driving the pixels to drive the display panel (DP) and a power management circuit that provides power for the operation of each unit are omitted for convenience of explanation.

The timing controller (TCON) may be configured to receive display data from an external source and provide display data DAT for displaying the screen as a packet in a preset format to the display driver (DIC). Detailed descriptions for receiving and transmitting display data of the timing controller (TCON) are omitted.

The display driver (DIC) may be configured to provide source signals Sout converted from display data to the display panel (DP).

The display driver (DIC) described above includes a data processor 10, a digital-to-analog converter 12, an output circuit 14, a gamma voltage provider 20, a compensation information storage unit 30, and a compensation unit 32. It can be configured to do so.

The data processor 10, the digital-to-analog converter 12, and the output circuit 14 are configured to process display data corresponding to a plurality of channels and output a source signal Sout to the plurality of channels. The plurality of channels may include subpixels corresponding to red, green, and blue.

The data processor 10 is configured to receive display data DAT comprised of packets from a timing controller (TCON), restore the display data, and provide the restored display data for each channel.

The digital-to-analog converter 12 is configured to output an analog voltage corresponding to digital display data. The digital-to-analog converter 12 is configured to output an analog voltage using gamma voltages VG for red for subpixels corresponding to red, and gamma voltages VG for green for subpixels corresponding to green. and is configured to output an analog voltage using gamma voltages VG for blue for subpixels corresponding to blue.

That is, the digital-to-analog converter 12 may be configured to receive gamma voltages VG corresponding to each subpixel, and may output an analog voltage by selecting a gamma voltage corresponding to display data.

The output circuit 14 is configured to output a source signal SOUT corresponding to an analog voltage for each channel. The output circuit 14 may include an output buffer (not shown) for each channel, and the output buffer may be understood as performing a buffer operation for the analog voltage.

The gamma voltage provider 20 digitally generates gamma voltages VG corresponding to each subpixel, that is, gamma voltages VG for red, green, and blue, in response to the sub-gray levels provided by the compensator 32. It may be configured to provide to the analog converter 12.

More specifically, the gamma voltage provider 20 may be initially set to provide gamma voltages assuming that the display panel DP corresponds to a preset gamma curve, for example, gamma 2.2 (G2.2).

According to an embodiment of the present invention, the gamma voltage provider 20 may be configured to provide gamma voltages corresponding to the changed gamma curve of the display panel DP. That is, the gamma voltage provider 20 may be configured to change the levels of the gamma voltages VG to levels corresponding to the gamma curve changed by the compensation control signals and output the gamma voltages VG at the changed level.

According to an embodiment of the present invention, the compensation information storage unit 30 stores sub-gray levels NSET (R4, G4, B4) for sub-pixels for white compensation for each of a plurality of image gray levels (NIGL) preset as compensation information. ) can be stored in the compensation lookup table.

The compensation unit 32 provides compensation control signals corresponding to sub-gray levels NSET (R4, G4, B4) for each of the plurality of image gray levels (NIGL) corresponding to the subpixels to the gamma voltage provider 20. You can.

By the above-described configuration, the gamma voltage provider 20 changes the gamma voltages VG to a level considering the optical compensation of the display panel DP and provides the gamma voltages VG at the changed level to the digital-analog converter 12. can do.

Therefore, the present invention can provide gamma voltages to subpixels using compensation information stored for optical compensation, and optical compensation for the display panel by converting display data into an analog signal in response to the gamma voltages whose levels have been changed. This can be done.

Claims (13)

Storing a test lookup table, wherein the test lookup table includes test sub-gray levels for sub-pixels for each test luminance level corresponding to a reference gamma curve for preset test image gray levels:
generating a measured luminance level and a measured sub-gray level by measuring the luminance of the display panel using first test sub-gray levels corresponding to the selected first test image gray level;
selecting second test sub-gray levels of a second test image gray level corresponding to the measured sub-gray levels from the test lookup table; and
Generating compensation information by correcting the second test sub-gray levels with a proportional relationship between the measured luminance level and the first test image gray level. The method of claim 1, wherein selecting the second test sub-gray levels comprises:
An optical compensation method for a display panel, wherein the second test sub-gray levels of the second test image gray level that most closely approximate the measured sub-gray levels are selected from the test look-up table. The method of claim 1, wherein generating the compensation information comprises:
Optics of a display panel that generates corrected sub-gray levels obtained by correcting the second test sub-gray levels for each sub-pixel of the second test image gray level according to the ratio of the measured luminance level and the first test image gray level. How to compensate. According to clause 3,
An optical compensation method for a display panel that generates the compensation information in which the correction sub-gray levels are stored with respect to the second test image gray level. According to clause 4,
An optical compensation method for a display panel that generates the correction information having a luminance level for the correction sub-gray levels that corresponds to a first test luminance level for the first test sub-gray levels. According to claim 1,
An optical compensation method for a display panel that corrects the second test sub-gray levels by multiplying the second test sub-gray levels by dividing the measured luminance level and the first test image gray level. a test information storage unit storing a test lookup table including test sub-gray levels for sub-pixels for each test luminance level corresponding to a reference gamma curve for preset test image gray levels;
a test execution unit providing display data corresponding to first test sub-gray levels corresponding to the first test image gray level selected from the test lookup table to the display panel;
Receives a measured luminance level and measured sub-gray levels corresponding to a result of the luminance measurement of the display panel, and a second test sub-gray level of a second test image gray level corresponding to the measured sub-gray levels in the test lookup table. a compensation information generator for generating compensation information by selecting sub-gray levels and correcting the second test sub-gray levels with a proportional relationship between the measured luminance level and the first test image gray level; and
An optical compensation system for a display panel comprising a compensation information storage unit that stores a compensation lookup table that stores the corrected sub-gray levels of the second test sub-gray levels with respect to the second test image gray level. . The method of claim 7, wherein the test execution unit,
An optical compensation system for a display panel that provides the display data for measuring luminance of the display panel at least once for each of the test image gray levels. The method of claim 7, wherein the compensation information generator,
An optical compensation system for a display panel that selects the second test sub-gray levels of the second test image gray level that most closely approximate the measured sub-gray levels in the test lookup table. The method of claim 7, wherein the compensation information generator,
Optics of a display panel that generates corrected sub-gray levels obtained by correcting the second test sub-gray levels for each sub-pixel of the second test image gray level according to the ratio of the measured luminance level and the first test image gray level. Reward system. The method of claim 10, wherein the compensation information generator,
a divider outputting the ratio of the measured luminance level and the first test image gray level; and
A multiplier that outputs the corrected sub-gray levels obtained by multiplying the second test sub-gray levels of the second test image gray level by the ratio. The method of claim 7, wherein the compensation information storage unit,
An optical compensation method for a display panel, wherein a luminance level corresponding to a first test luminance level for the first test sub-gray levels is set for the correction sub-gray levels. a compensation information storage unit that stores sub-gray levels for sub-pixels for white compensation for each of a plurality of preset image gray levels as compensation information;
a compensation unit providing compensation control signals corresponding to sub-gray levels for each of the plurality of image gray levels corresponding to a specific sub-pixel;
a gamma voltage provider providing gamma voltages for expressing luminance of the specific subpixel; and
A digital-to-analog converter that converts display data for the specific sub-pixel into an analog signal using the gamma voltages,
The gamma voltage provider changes the levels of the gamma voltages from first levels corresponding to a preset reference gamma curve to second levels corresponding to a gamma curve changed by the compensation control signals for optical compensation. A display driver with an optical compensation function.

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