VOLTAGE DROP COMPENSATION METHOD AND DEVICE THEREOF, DISPLAY DEVICE

• US 20200051508A1
• Filed: 06/14/2019
• Published: 02/13/2020
• Est. Priority Date: 08/07/2018
• Status: Active Grant

• Current Assignee: BOE Technology Group Co., Ltd.
• Original Assignee: BOE Technology Group Co., Ltd.
• Inventors: TAN, Wenjing, ZHAO, Hui
• Granted Patent: US 10,885,856 B2
• Time in Patent Office: Days
• CPC Class Codes: G09G 2300/043 Compensation electrodes or other additional electrodes in matrix displays related to distortions or compensation signals, e.g. for modifying TFT threshold voltage in column driver
• CPC Class Codes: G09G 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0271 Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3225 using an active matrix
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements

Abstract

A voltage drop compensation method and a device thereof, and a display device are disclosed. The voltage drop compensation method includes: obtaining an impedance distribution of the plurality of rows of pixels, and constructing a voltage drop model based on the impedance distribution of the plurality of rows of pixels; obtaining a source-end input current of the display panel; determining an input value of the voltage drop model based on the source-end input current, and determining at least one voltage drop corresponding to the at least one pixel row to be compensated according to the input value; and determining, according to the at least one voltage drop, at least one compensation grayscale which is in one-to-one correspondence with the at least one pixel row to be compensated respectively and performing grayscale compensation on the at least one pixel row to be compensated based on the at least one compensation grayscale.

Claims

1. A voltage drop compensation method, adapted for a display panel, the display panel comprising a plurality of rows of pixels, and the plurality of rows of pixels comprising at least one pixel row to be compensated,

wherein the voltage drop compensation method comprises:

obtaining an impedance distribution of the plurality of rows of pixels, and constructing a voltage drop model based on the impedance distribution of the plurality of rows of pixels;

obtaining a source-end input current of the display panel, where the source-end input current refers to a total current before the total current is shunt into the plurality of rows of pixels;

determining an input value of the voltage drop model based on the source-end input current, and determining at least one voltage drop corresponding to the at least one pixel row to be compensated according to the input value of the voltage drop model; and

determining, according to the at least one voltage drop, at least one compensation grayscale which is in one-to-one correspondence with the at least one pixel row to be compensated respectively and performing grayscale compensation on the at least one pixel row to be compensated based on the at least one compensation grayscale.

2. The voltage drop compensation method according to claim 1, wherein the impedance distribution of the plurality of rows of pixels is an impedance distribution of the plurality of rows of pixels in a case where the display panel is at a maximum display brightness, and the source-end input current is a source-end input current of the display panel upon real-time display.

3. The voltage drop compensation method according to claim 2, wherein determining the input value of the voltage drop model based on the source-end input current comprises:

judging whether or not the source-end input current is greater than a current threshold; and

taking the source-end input current as the input value of the voltage drop model in a case where the source-end input current is greater than the current threshold.

4. The voltage drop compensation method according to claim 3, wherein the plurality of rows of pixels comprise P pixel rows to be compensated, P is an integer greater than 1,

determining at least one voltage drop corresponding to the at least one pixel row to be compensated according to the input value of the voltage drop model comprises:

determining P voltage drops corresponding to the P pixel rows to be compensated according to the input value of the voltage drop model; and

determining, according to the at least one voltage drop, at least one compensation grayscale which is in one-to-one correspondence with the at least one pixel row to be compensated respectively and performing grayscale compensation on the at least one pixel row to be compensated based on the at least one compensation grayscale comprises;

determining P compensation grayscales which are in one-to-one correspondence with the P pixel rows to be compensated based on the P voltage drops respectively and performing the grayscale compensation on the P pixel rows to be compensated based on the P compensation grayscales.

5. The voltage drop compensation method according to claim 4, wherein after judging whether or not the source-end input current is larger than the current threshold, the voltage drop compensation method further comprises:

taking a maximum current of the display panel at the maximum display brightness as the input value of the voltage drop model in a case where the source-end input current is less than or equal to the current threshold,

determining P compensation grayscales which are in one-to-one correspondence with the P pixel rows to be compensated based on the P voltage drops respectively and performing the grayscale compensation on the P pixel rows to be compensated based on the P compensation grayscales comprises;

determining the P compensation grayscales of the P pixel rows to be compensated in the display panel based on the P voltage drops, and determining a grayscale compensation mean value based on the P compensation grayscales;

multiplying a percentage of the source-end input current in the maximum current by the grayscale compensation mean value to obtain a grayscale compensation reference value of the display panel upon real-time display;

performing the grayscale compensation on an initial pixel row to be compensated, at a first side of the P pixel rows to be compensated close to a drive circuit, of the P pixel rows to be compensated according to the grayscale compensation reference value;

increasing progressively a grayscale increment in sequence on the grayscale compensation reference value, so as to obtain (P-1) grayscale compensation values corresponding to (P-1) pixel rows to be compensated of the P pixel rows to be compensated except the initial pixel row to be compensated, along a direction from the first side of the P pixel rows to be compensated close to the drive circuit to a second side of the P pixel rows to be compensated away from the drive circuit, the (P-1) grayscale compensation values corresponding to the (P-1) pixel rows to be compensated sequentially increasing; and

performing the grayscale compensation on the (P-1) pixel rows to be compensated according to the (P-1) grayscale compensation values.

6. The voltage drop compensation method according to claim 4, wherein a number of the plurality of rows of pixels is the same as a number of the P pixel rows to be compensated.

7. The voltage drop compensation method according to claim 1, wherein a plurality of row resistances corresponding to the plurality of rows of pixels in the display panel are all equal, and a (n1)-th voltage drop corresponding to a (n1)-th pixel row in the plurality of rows of pixels satisfies a following formula:

8. The voltage drop compensation method according to claim 7, wherein in a case where the plurality of row resistances are equal to the source-end input resistance of the display panel, the (n1)-th voltage drop corresponding to the (n1)-th pixel row in the plurality of rows of pixels satisfies a following formula:

9. The voltage drop compensation method according to claim 1, wherein determining, according to the at least one voltage drop, at least one compensation grayscale which is in one-to-one correspondence with the at least one pixel row to be compensated respectively comprises:

predicting, according to the at least one voltage drop, at least one display current of the at least one pixel row to be compensated respectively after voltage drop occurs, and according to the at least one display current, converting the at least one voltage drop into at least one equivalent grayscale corresponding to the at least one pixel row to be compensated respectively; and

according to a difference between a target grayscale of each pixel row to be compensated and an equivalent grayscale corresponding to each pixel row to be compensated among the at least one equivalent grayscale, determining a compensation grayscale corresponding to each pixel row to be compensated respectively.

10. The voltage drop compensation method according to claim 9, wherein according to the at least one display current, converting the at least one voltage drop into at least one equivalent grayscale corresponding to the at least one pixel row to be compensated respectively comprises:

according to a corresponding relationship between a display current of a corresponding pixel row to be compensated and a display brightness of the corresponding pixel row to be compensated and a corresponding relationship between the display brightness and a grayscale of the corresponding pixel row to be compensated, determining a corresponding relationship between the display current and the grayscale; and

according to the corresponding relationship between the display current and the grayscale, converting the at least one voltage drop into the at least one equivalent grayscale, respectively.

11. The voltage drop compensation method according to claim 10, wherein

the corresponding relationship between the display current and the display brightness satisfies a formula:

Lum=EF×

I;

where, I is the display current of the corresponding pixel row to be compensated, Lum is the display brightness of the corresponding pixel row to be compensated, and EF represents a conversion coefficient;

the corresponding relationship between the display brightness and the grayscale satisfies a formula;

Lum=A×

Gray^m, m=2.2;

where, A is a grayscale coefficient of the display panel, and Gray is the grayscale of the corresponding pixel row to be compensated;

a (n2)-th display current I_n2, corresponding to a (n2)-th pixel row to be compensated among the at least one pixel row to be compensated, among the at least one display current satisfies a formula;

I_n2=½

×

K×

(V_{data n2}−

V_DDn2)²;

an equivalent grayscale of the (n2)-th pixel row to be compensated satisfies a formula;

A×

(Gray′

)^2.2=½

×

K×

(V_{data n2}−

V_DDn2)²;

where V_DDn2=V_DD−

Δ

V_n2;

V_DDn2 is a working voltage of the (n2)-th pixel row to be compensated, V_DD is a source-end input voltage of the display panel, and Δ

V_n2 is a (n2)-th voltage drop corresponding to the (n2)-th pixel row to be compensated;

Gray′

is an equivalent grayscale of the (n2)-th pixel row to be compensated, K is a voltage-current conversion coefficient, V_{data n2} is a data line voltage for the (n2)-th pixel row to be compensated, and n2 is a positive integer and is less than or equal to a number of the at least one pixel row to be compensated.

12. The voltage drop compensation method according to claim 11, wherein

a target grayscale G₀ of the (n2)-th pixel row to be compensated satisfies a formula:

V_DD×

G₀+b, the equivalent grayscale Gray′

of the (n2)-th pixel row to be compensated satisfies a formula;

V_DDn2=a×

Gray′

+b;

a compensation grayscale Δ

G_n of the (n2)-th pixel row to be compensated satisfies a formula;

Δ

G_n=G₀−

Gray′

=Δ

V_n2/a;

where a is a linear coefficient of a gamma voltage in the display panel, and b is a constant term of the gamma voltage in the display panel.

13. A voltage drop compensation device, configured to perform compensation on a display panel, the display panel comprising a plurality of rows of pixels, and the plurality of rows of pixels comprising at least one pixel row to be compensated,

wherein the voltage drop compensation device comprises:

a current sensor, configured to detect a source-end input current of the display panel;

a voltage drop determining module connected to the current sensor, comprising a voltage drop model constructed based on an impedance distribution of the plurality of rows of pixels, and configured to determine an input value of the voltage drop model based on the source-end input current, and determine at least one voltage drop corresponding to the at least one pixel row to be compensated according to the input value of the voltage drop model; and

a grayscale compensation module connected to the voltage drop determining module, configured to determine, according to the at least one voltage drop, at least one compensation grayscale which is in one-to-one correspondence with the at least one pixel row to be compensated respectively, and to perform grayscale compensation on the at least one pixel row to be compensated based on the at least one compensation grayscale.

14. The voltage drop compensation device according to claim 13, wherein the voltage drop determining module and the grayscale compensation module are integrated into a panel driving chip of the display panel.

15. The voltage drop compensation device according to claim 13, wherein the grayscale compensation module is further respectively connected with the at least one pixel row to be compensated through data lines, so as to perform the grayscale compensation on the at least one pixel row to be compensated based on the at least one compensation grayscale.

16. The voltage drop compensation device according to claim 13, wherein the voltage drop determining module is configured to:

judge whether or not the source-end input current is greater than a current threshold; and

take the source-end input current as the input value of the voltage drop model in a case where the source-end input current is greater than the current threshold.

17. The voltage drop compensation device according to claim 16, wherein the plurality of rows of pixels comprise P pixel rows to be compensated, P is an integer greater than 1,

the voltage drop determining module is configured to:

determine P voltage drops corresponding to the P pixel rows to be compensated according to the input value of the voltage drop model;

the grayscale compensation module is configured to;

determine P compensation grayscales which are in one-to-one correspondence with the P pixel rows to be compensated based on the P voltage drops respectively, and perform the grayscale compensation on the P pixel rows to be compensated based on the P compensation grayscales.

18. The voltage drop compensation device according to claim 17, wherein the impedance distribution of the plurality of rows of pixels is an impedance distribution of the plurality of rows of pixels in a case where the display panel is at a maximum display brightness, and the source-end input current is a source-end input current of the display panel upon real-time display,

after judging whether or not the source-end input current is larger than the current threshold, the voltage drop determining module is further configured to:

take a maximum current of the display panel at the maximum display brightness as the input value of the voltage drop model in a case where the source-end input current is less than or equal to the current threshold;

the grayscale compensation module is further configured to;

determine the P compensation grayscales of the P pixel rows to be compensated in the display panel based on the P voltage drops, and determine a grayscale compensation mean value based on the P compensation grayscales;

multiply a percentage of the source-end input current in the maximum current by the grayscale compensation mean value to obtain a grayscale compensation reference value of the display panel upon real-time display;

perform the grayscale compensation on an initial pixel row to be compensated, at a first side of the P pixel rows to be compensated close to a drive circuit, of the P pixel rows to be compensated according to the grayscale compensation reference value;

increase progressively a grayscale increment in sequence on the grayscale compensation reference value, so as to obtain (P-1) grayscale compensation values corresponding to (P-1) pixel rows to be compensated of the P pixel rows to be compensated except the initial pixel row to be compensated, along a direction from the first side of the P pixel rows to be compensated close to the drive circuit to a second side of the P pixel rows to be compensated away from the drive circuit, the (P-1) grayscale compensation values corresponding to the (P-1) pixel rows to be compensated sequentially increasing; and

perform the grayscale compensation on the (P-1) pixel rows to be compensated according to the (P-1) grayscale compensation values.

19. The voltage drop compensation device according to claim 13, wherein the grayscale compensation module is configured to:

predict, according to the at least one voltage drop, at least one display current of the at least one pixel row to be compensated respectively after voltage drop occurs, and according to the at least one display current, convert the at least one voltage drop into at least one equivalent grayscale corresponding to the at least one pixel row to be compensated respectively; and

according to a difference between a target grayscale of each pixel row to be compensated and an equivalent grayscale corresponding to each pixel row to be compensated among the at least one equivalent grayscale, determine a compensation grayscale corresponding to each pixel row to be compensated respectively.

20. A display device, comprising a display panel and a voltage drop compensation device,

wherein the voltage drop compensation device is configured to perform compensation on the display panel, the display panel comprises a plurality of rows of pixels, and the plurality of rows of pixels comprises at least one pixel row to be compensated,

the voltage drop compensation device comprises:

a current sensor, configured to detect a source-end input current of the display panel;

a voltage drop determining module connected to the current sensor, comprising a voltage drop model constructed based on an impedance distribution of the plurality of rows of pixels, and configured to determine an input value of the voltage drop model based on the source-end input current, and determine at least one voltage drop corresponding to the at least one pixel row to be compensated according to the input value of the voltage drop model; and

a grayscale compensation module connected to the voltage drop determining module, configured to determine, according to the at least one voltage drop, at least one compensation grayscale which is in one-to-one correspondence with the at least one pixel row to be compensated respectively, and perform grayscale compensation on the at least one pixel row to be compensated based on the at least one compensation grayscale.