CN114999387A - Display brightness compensation method based on temperature feedback - Google Patents

Abstract

The invention discloses a temperature feedback-based display brightness compensation method, which comprises the following steps: acquiring basic temperature compensation data Delta Di corresponding to a reference OLED according to temperature change; calculating calibration temperature compensation data delta Dx generated by each OLED relative to a reference OLED according to self parameter difference; and (3) for each OLED display, the brightness of the display is subjected to supplementary adjustment in a mode of jointly compensating the basic temperature compensation data delta Di and the calibration temperature compensation data delta Dx corresponding to the temperature of the OLED display. The invention has the advantages that: the influence of temperature on the reference OLED and the difference between the performances of each screen are considered, basic temperature compensation data and calibration temperature compensation data are respectively arranged, and the VCOM voltage corresponding to the brightness adjustment is adjusted in a mode of coaction of the two temperature compensation data, so that the brightness display difference between different OLEDs is reduced.

Description

A Compensation Method of Display Brightness Based on Temperature Feedback

technical field

The invention relates to the field of silicon-based OLED displays, in particular to a method for compensating display brightness based on temperature feedback.

Background technique

In recent years, microdisplays have gradually emerged, and silicon-based OLEDs are one of the microdisplays. Silicon-based OLEDs have the advantages of high brightness, high color gamut, high contrast, low power consumption, low driving voltage, fast response speed, and relatively mature technology. , has become a mainstream microdisplay technology. Silicon-based OLED has a wide range of application scenarios, such as aiming, observation systems, helmet systems and simulation training systems, VR./AR and other near-eye displays.

The light emission of OLED diodes depends on the migration and recombination of organic carriers. The migration of organic carriers has obvious temperature characteristics, so the luminescence brightness of OLED displays also has corresponding temperature characteristics. In constant voltage driving mode, OLED emits light. Brightness increases with ambient temperature. Therefore, in order to maintain the consistency of the OLED brightness in a wide temperature range, it is necessary to compensate the display brightness of the OLED. Generally, the voltage across the OLED diode is adjusted by changing the voltage of VCOM or the pulse width of VCOM. Thus, the display brightness of the OLED is adjusted.

In the prior art, the brightness compensation LUT table based on temperature feedback stores the absolute value of the VCOM register corresponding to each temperature under the same brightness. There are differences in the display effect of the OLED display screen. The VCOM value required to achieve the same display brightness at the same temperature Different, using the original brightness compensation method based on temperature feedback to test a set of temperature compensation data may not be suitable for all displays, so it may be necessary to test multiple sets of temperature compensation data to match different OLED displays, and the compensation effect may be better. It is not ideal, so it is necessary to develop a brightness compensation method based on temperature feedback that can eliminate or reduce the display brightness difference between different display screens, improve the temperature compensation display effect, and at the same time can improve the temperature compensation efficiency.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a compensation method for display brightness based on temperature feedback. By considering the difference of each display screen, the corresponding compensation value is obtained for control, so as to reduce the difference of display brightness effect between each OLED display screen.

In order to achieve the above purpose, the technical solution adopted in the present invention is: a compensation method for the brightness of a display based on temperature feedback, including the following methods:

Obtain the basic temperature compensation data ΔD _i corresponding to the temperature change of a benchmark OLED;

Calculate the calibration temperature compensation data ΔD _x generated by each OLED relative to the reference OLED for its own parameter differences;

For each OLED display, the basic temperature compensation data ΔD _i corresponding to its temperature and the calibration temperature compensation data ΔD _x are used to supplement the brightness of the display.

The basic temperature compensation data △D _i acquisition methods include:

For a benchmark OLED display, set the target brightness at room temperature and obtain the VCOM voltage value corresponding to the target brightness and the register value D _{room temperature} corresponding to the voltage value;

For a benchmark OLED display, test the register value D _i corresponding to the VCOM voltage value required to achieve the target brightness at different temperatures, where i is the temperature;

Calculate the VCOM compensation value of the benchmark OLED display at different temperatures relative to room temperature to obtain the basic temperature compensation data ΔD _i .

The VCOM compensation value of the benchmark OLED display at different temperatures relative to room temperature is calculated by using linear interpolation method, quadratic function expression, cubic function expression, or the method of fitting a higher-order function expression, and the benchmark is calculated to obtain the benchmark The difference ΔD _i or the scale factor value α _i between the register value corresponding to VCOM of the OLED at each temperature and the register value corresponding to VCOM at room temperature.

The calculation method of calibration temperature compensation data is:

Obtain the register value D _x corresponding to the VCOM voltage value required by each OLED to reach the target brightness at room temperature, and calculate the difference ΔD _x or the scale factor between the register value D and _{room temperature} corresponding to the VCOM at room temperature of the basic temperature compensation data β _x , get the calibration temperature compensation data.

When controlling the brightness of each screen, the current ambient temperature of the screen is read through the temperature sensor in the screen IC, and the VCOM voltage compensation under the combined action of the basic temperature compensation data and the calibration temperature compensation data at the current temperature is obtained. value to control the display.

The VCOM voltage compensation value under the combined action of the basic temperature compensation data and the calibration temperature compensation data is

ΔD _if =ΔD _x +ΔD _i or ΔD _if =D _{room temperature} *β _x *α _i .

The advantages of the present invention are: considering the influence of temperature on the reference OLED and the difference between the performance of each screen itself, the basic temperature compensation data and the calibration temperature compensation data are respectively set, and the brightness is adjusted by the combined action of the two temperature compensation data. The corresponding VCOM voltage is adjusted to make the brightness display difference between different OLEDs smaller, and in this way, multiple OLED displays with the same target brightness can share a set of temperature compensation data, which indirectly improves the temperature compensation feedback based. Efficiency of brightness compensation.

Description of drawings

Below is a brief description of the content expressed in each of the drawings in the description of the present invention and the labels in the drawings:

Fig. 1 is the flow chart of the implementation principle of brightness compensation of the present invention;

Fig. 2 is the VCOM compensation data LUT table generation flow chart of the present invention;

FIG. 3 shows the relationship between the VCOM corresponding register value and the temperature under the same brightness of the present invention.

Detailed ways

The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and through the description of the preferred embodiments.

As shown in FIG. 1, it is a flowchart of the implementation of brightness compensation of the present application, and its specific scheme includes the following steps;

1) Obtain the current ambient temperature through the temperature sensor inside the display IC chip;

Select the appropriate VCOM compensation sub-table from the pre-calibrated LUT table according to actual needs; different VCOM compensation sub-tables include: the compensation sub-table obtained by linear interpolation, the compensation sub-table obtained by the second-order function expression method, and the The compensation sub-table obtained by the third-order function expression, the compensation sub-table obtained by using the higher-order function expression, etc...

Provide a variety of compensation sub-tables in the early stage of design, in order to match the actual display effect of OLED as much as possible.

2) Obtain the VCOM compensation value ΔD _if =ΔD _x +ΔD _i or ΔD _if =D _{room temperature} *β _x *α _i at the current temperature based on the selected VCOM compensation sub-table;

3) Send the corresponding VCOM voltage compensation value to the voltage driver;

4) The voltage driver drives the OLED according to the obtained compensation value, changes the voltage across the OLED, and adjusts the display brightness of the OLED display.

The LUT lookup table includes the following sections:

Basic temperature compensation data composed of the difference (or scale factor) between the VCOM voltage value at different temperatures and the VCOM voltage value at room temperature (such as 25°C) to achieve the same brightness, and the VCOM of different screens at room temperature (such as 25°C) The calibration temperature compensation data composed of the difference (or scale factor) of the voltage value and the VCOM voltage value at room temperature (such as 25°C) of the basic temperature compensation data, as shown in Table 1:

In this application, the LUT table is the pre-calibrated basic temperature compensation data and calibration temperature compensation data for different displays and different temperatures. The principle is shown in Figure 2.

The data in the above LUT tables are obtained after testing and data processing. The specific methods are as follows:

1) Set the required target brightness at room temperature, select a benchmark OLED and obtain the register value D _{room temperature} corresponding to the VCOM voltage value corresponding to the benchmark OLED at the target brightness and room temperature;

In this application, a reference OLED is selected or set. Reference OLED: the register value corresponding to the VCOM voltage value corresponding to the set target brightness at room temperature is D _{room temperature} ; other OLEDs: the VCOM voltage value corresponding to the set target brightness at room temperature corresponds to The register value of is Dx..

2) By testing the register value Di corresponding to the VCOM voltage value required to achieve the target brightness at different temperatures in a high and low temperature test chamber, the Di corresponding to different _i is the corresponding register value Di when the temperature is i.

Get a set of unprocessed VCOM values (D ₁ , D ₂ , D ₃ , ..., D _m );

3) Select an appropriate data processing method to obtain the VCOM compensation value at each temperature relative to room temperature (such as 25°C), such as linear interpolation, quadratic function expression, cubic function expression, or fitting more The method of higher-order function expression, the VCOM compensation value can be the difference ΔD _i between the register value corresponding to VCOM at each room temperature and the register value corresponding to VCOM at room temperature, or it can be the scale factor value α _i , to obtain the basis temperature compensation data;

4) Linear interpolation method: y=ax+b, need two groups of (x, y) to solve to get a, b;

5) Quadratic function expression method: y=ax2+bx+c, three groups of (x, y) are needed to obtain a, b, c;

6) Cubic function expression method: y=ax3+bx2+cx+d, four groups of (x, y) are needed to obtain a, b, c, d;

7) Quadratic function expression method: y=ax ⁴ +bx3+cx2+dx+e, five groups of (x,y) are needed to solve to get a,b,c,d,e;

8) Example: When testing basic temperature compensation data, in order to save time and reduce workload, the test temperature range is -40°C to 70°C, and a data is tested every 10°C. In the actual temperature compensation process, every 1/1 2/3/4/5°C is used for temperature compensation, so it is necessary to calculate the VCOM compensation value difference ΔD _i or α _i at other temperatures by using the formula. A curve is formed by simulating part of the point temperature data, and then all the data is formed by the curve.

Each screen needs to perform OTP. During OTP, obtain the register value _Dx corresponding to the VCOM voltage value required by each screen to reach the target brightness at room temperature (such as 25°C). By calculating the basis of the reference OLED The difference ΔD _x or the scale factor β _x of the register value D corresponding to the VCOM of the temperature compensation data at room temperature (such as 25°C), to obtain the calibration temperature compensation data; α _i : corresponding to the VCOM values obtained at different temperatures of the reference OLED The ratio of the register value D _i to the VCOM value at room temperature corresponding to the register value D _{room temperature} , that is, α _i =D _i /D _{room temperature} ;

β _x : the ratio of the register value D _x corresponding to the VCOM value obtained by other OLEDs at room temperature and the register value D _{room temperature} corresponding to the VCOM value of the reference OLED at room temperature, that is, β _x =D _x /D _{room temperature} ;

△D _x and △D _i are both register values, and the register value saves the VCOM voltage compensation value;

9)

The final VCOM compensation value is composed of the basic temperature compensation data and the calibration temperature compensation data:

△D _if =△D _x +△D _i or △D _if =D _{room temperature} * _βx * _αi ;

By testing multiple sets of data, the basic temperature compensation data and calibration temperature compensation data corresponding to different OLEDs at different temperatures can be obtained to form a LUT table.

The LUT table obtained through the above experimental calibration will be pre-stored or saved in the memory and register of the IC chip, which is convenient for checking the LUT table in time to obtain the corresponding VCOM voltage value when the display screen is actually working, thus realizing the brightness of the display. adjust.

In this application, the benchmark OLED needs to test the following data: The register value corresponding to the VCOM value required to achieve the same target brightness at different temperatures: D _{room temperature} , D _i , i is the temperature value, and D _i and D _{room temperature} are compared to obtain the reference temperature compensation data △D _i or α _i ;

For other OLEDs, it is only necessary to test the register value D _x corresponding to the VCOM value at room temperature, and compare it with the D _{room temperature} of the benchmark OLED to obtain ΔD _x or β _x .

As shown in Figure 3, the relationship between the VCOM register value and temperature under the same brightness achieved by the linear interpolation method and the quadratic function expression can be seen. The relationship between the register and temperature at different temperatures can be seen. The compensation sub-table obtained by the compensation algorithm has a difference in the compensated brightness value, so it is necessary to match an appropriate compensation algorithm for the actual display effect of the OLED. In this way, limited test data is used to fit and form a curve. According to the curve, as many VCOM values corresponding to each temperature can be obtained as much as possible without requiring a large amount of test data. The application can use limited data fitting. To achieve more accurate acquisition of VCOM data of temperature points.

In another preferred embodiment, the present application also provides a method for calculating basic temperature compensation data. The basic temperature compensation data is processed by calculating the corresponding register value of the VCOM at each temperature relative to the VCOM of the adjacent temperature. The difference ΔDi of the register values can also be the scale factor value αi to obtain the basic temperature compensation data, where the adjacent temperature is defined as follows: the adjacent temperature lower than room temperature (such as 25°C) is the next higher temperature than it. point, the adjacent temperature higher than room temperature (such as 25°C) is the previous temperature point lower than it;

In the present application, by storing the relative difference (or proportional coefficient) of the VCOM register of each temperature under the same brightness relative to the room temperature, the display effect difference of multiple OLED display screens can be reduced, and the brightness compensation effect of the OLED display screen can be improved; The calibration temperature compensation data is composed of the difference (or scale factor) of the VCOM register value of each OLED display screen relative to the basic temperature compensation data at room temperature (such as 25°C), which further reduces the display effect difference of different OLED display screens. , which enhances the brightness compensation effect; the LUT table contains a variety of optional VCOM compensation sub-tables, and the appropriate VCOM compensation sub-table can be selected for brightness compensation according to actual needs, in order to achieve the optimal brightness compensation effect;

The technical effects of this application include:

(1) The original brightness compensation LUT table based on temperature feedback stores the absolute value of the VCOM register corresponding to each temperature under the same brightness. The existing solution stores the relative difference value of each temperature under the same brightness relative to the VCOM register at room temperature. (or proportional coefficient) constitute the basic temperature compensation data, which can reduce the display effect difference of multiple OLED displays and improve the brightness compensation effect of OLED displays;

(2) By increasing the calibration temperature compensation data composed of the difference (or scale factor) of the VCOM voltage value of each OLED display screen relative to the VCOM voltage value of the basic temperature compensation data at room temperature (such as 25°C), the difference is further reduced. The display effect of the OLED display is different, which enhances the brightness compensation effect;

(3) The LUT table contains a variety of optional VCOM compensation sub-tables, and the appropriate VCOM compensation sub-table can be selected for brightness compensation according to actual needs, in order to achieve the optimal brightness compensation effect;

(4) There are differences in the display effect of OLED displays. The VCOM values required to achieve the same display brightness are different at the same temperature. Therefore, using the original brightness compensation method based on temperature feedback to test a set of temperature compensation data may not be possible. It is applicable to all display screens, and in this way, multiple OLED displays with the same target brightness can share a set of temperature compensation data, which indirectly improves the efficiency of brightness compensation based on temperature compensation feedback.

Obviously, the specific implementation of the present invention is not limited by the above-mentioned manner, as long as various insubstantial improvements made by adopting the method concept and technical solution of the present invention are all within the protection scope of the present invention.

Claims (9)

1. The temperature feedback-based display brightness compensation method is characterized by comprising the following steps of: the method comprises the following steps:

acquiring basic temperature compensation data Delta D corresponding to temperature change of a reference OLED _i ；

Calculating the calibration generated by each OLED relative to the reference OLED according to the parameter differenceTemperature compensation data Delta D _x ；

Respectively adopting basic temperature compensation data Delta D corresponding to the temperature of each OLED display _i And calibrating the temperature compensation data Delta D _x The common compensation mode is used for supplementing the adjustment of the brightness of the display.

2. The method of claim 1, wherein the method comprises: basic temperature compensation data Delta D _i The acquisition method comprises the following steps:

for a reference OLED display, setting target brightness at room temperature and obtaining VCOM voltage value corresponding to the target brightness and register value D corresponding to the voltage value _{At room temperature} ；

For a reference OLED display, testing the register value D corresponding to VCOM voltage value required for reaching the target brightness at different temperatures _i Wherein i is temperature;

calculating to obtain VCOM compensation value of the reference OLED display at different temperatures relative to room temperature so as to obtain basic temperature compensation data delta D _i 。

3. The method of claim 2, wherein the method comprises: calculating to obtain a difference value delta D of a register value corresponding to the VCOM of the reference OLED at each temperature relative to a register value corresponding to the VCOM at the room temperature by adopting a linear interpolation method, a quadratic function expression, a cubic function expression or a method of fitting a higher-order function expression relative to the VCOM compensation value at the room temperature of the reference OLED display at different temperatures _i Or scale factor value alpha _i 。

4. The method for compensating brightness of a display based on temperature feedback according to claim 1 or 2, wherein: the calculation mode of the calibration temperature compensation data is as follows:

obtaining a register value D corresponding to the VCOM voltage value required by each OLED when the OLED reaches the target brightness at room temperature _x By calculating a register corresponding to VCOM at room temperature for the basic temperature compensation dataValue D _{At room temperature} Difference of (D) _x Or a scale factor beta _x And obtaining calibration temperature compensation data.

5. The method for compensating brightness of a display based on temperature feedback according to claim 1 or 2, wherein:

when the brightness of each screen is controlled, the current ambient temperature of the screen is read through a temperature sensor in the screen IC, and VCOM voltage compensation values under the combined action of the obtained basic temperature compensation data and the calibration temperature compensation data at the current temperature are obtained to control the display screen.

6. The method of claim 5, wherein the temperature feedback-based display brightness compensation method comprises: the VCOM voltage compensation value under the combined action of the basic temperature compensation data and the calibration temperature compensation data is delta D _if ＝△D _x +△D _i Or Δ D _if ＝D _{At room temperature} *β _x *α _i 。

7. The method of claim 1, wherein the method comprises: the reference OLED display is a pre-selected calibrated OLED display.

8. A method of temperature feedback based compensation of display brightness according to claim 2, characterized by: obtaining corresponding basic temperature compensation data Delta D under a plurality of temperatures through tests _i Then, fitting by linear interpolation, quadratic function expression, cubic function expression or method fitting higher order function expression to obtain corresponding temperature and corresponding basic temperature compensation data Delta D _i The basic temperature compensation data Delta D under the temperature which is not obtained by the test is obtained based on the fitting curve _i 。

9. A method for temperature feedback based compensation of display brightness according to any of claims 1-8, characterized by: the corresponding voltage compensation values at different temperatures are stored in the display IC in the VCOM compensation sub-table.

Images