Compensation method for display brightness based on temperature feedback

Abstract

The application discloses a compensation method for display brightness based on temperature feedback, comprising the following methods: obtaining basic temperature compensation data Di corresponding to temperature change of a reference OLED; calculating calibration temperature compensation data Dx of each OLED relative to the reference OLED due to parameter difference; and adjusting the display brightness of each OLED by using the basic temperature compensation data Di and the calibration temperature compensation data Dx corresponding to the temperature of the OLED. The application has the advantages that the basic temperature compensation data and the calibration temperature compensation data are set according to the influence of temperature on the reference OLED and the difference between the performances of each OLED, the two temperature compensation data are used to adjust the VCOM voltage corresponding to the brightness adjustment, and the brightness display difference between different OLEDs is reduced.

Description

Technical Field

[0001] This invention relates to the field of silicon-based OLED displays, and particularly to a method for compensating display brightness based on temperature feedback. Background Technology

[0002] In recent years, microdisplays have gradually emerged, and silicon-based OLED is one type of microdisplay. Silicon-based OLED boasts advantages such as high brightness, wide color gamut, high contrast, low power consumption, low driving voltage, fast response speed, and relatively mature technology, making it a mainstream microdisplay technology. Silicon-based OLED has a wide range of applications, including aiming and observation systems, helmet systems, simulation training systems, and near-eye displays such as VR / AR.

[0003] OLED diode light emission relies on the migration and recombination of organic charge carriers. The migration of organic charge carriers exhibits significant temperature characteristics; therefore, the brightness of an OLED display also has corresponding temperature characteristics. In constant-voltage driving mode, the OLED brightness increases with increasing ambient temperature. Therefore, to ensure consistent OLED brightness over a relatively wide temperature range, brightness compensation is necessary. This is typically achieved by adjusting the voltage across the OLED diode by changing the magnitude or pulse width of the VCOM voltage, thereby regulating the OLED's brightness.

[0004] In existing technologies, the brightness compensation LUT table based on temperature feedback stores the absolute values ​​of the VCOM registers corresponding to various temperatures at the same brightness. However, OLED displays exhibit varying display effects, and the VCOM values ​​required to achieve the same display brightness at the same temperature differ. Therefore, testing a set of temperature-compensated data using the existing temperature feedback-based brightness compensation method may not be applicable to all displays. Consequently, multiple sets of temperature-compensated data may need to be tested to match different OLED displays, and the compensation effect may still be unsatisfactory. Thus, it is necessary to develop a brightness compensation method based on temperature feedback that can eliminate or reduce the differences in display brightness between different displays, improve the temperature-compensated display effect, and enhance the temperature compensation efficiency. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for compensating display brightness based on temperature feedback. By taking into account the differences of each display screen and obtaining corresponding compensation values ​​for control, the difference in display brightness between different LED displays is reduced.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a display brightness compensation method based on temperature feedback, comprising the following methods:

[0007] Obtain the baseline temperature compensation data △D of a reference OLED in response to temperature changes.i ;

[0008] Calculate the calibration temperature compensation data ΔD for each OLED relative to the reference OLED based on its own parameter differences. x ;

[0009] For each OLED display, the baseline temperature compensation data ΔD corresponding to its temperature is used. i and calibration temperature compensation data △D x The brightness of the display is adjusted by means of joint compensation.

[0010] Basic temperature compensation data △D i The methods for obtaining the information include:

[0011] For a reference OLED display, a target brightness is set at room temperature, and the VCOM voltage value corresponding to the target brightness and the register value D corresponding to that voltage value are obtained. 室温 ;

[0012] For a benchmark OLED display, the register value D corresponding to the VCOM voltage required to achieve the target brightness is tested at different temperatures. i , where i is the temperature;

[0013] The VCOM compensation values ​​of the benchmark OLED display at different temperatures relative to room temperature were calculated to obtain the basic temperature compensation data ΔD. i .

[0014] The VCOM compensation values ​​of the benchmark OLED display at different temperatures relative to room temperature were calculated using linear interpolation, quadratic function expressions, cubic function expressions, or fitting higher-order function expressions. The difference ΔD between the register value corresponding to VCOM at each temperature and the register value corresponding to VCOM at room temperature was calculated. i Or the scaling factor value α i .

[0015] The calibration temperature compensation data is calculated as follows:

[0016] Obtain the register value D corresponding to the VCOM voltage required for each OLED to achieve the target brightness at room temperature. x By calculating the register value D corresponding to VCOM at room temperature based on the baseline temperature compensation data. 室温 The difference △D x Or the scaling factor β x The calibration temperature compensation data was obtained.

[0017] When controlling the brightness of each screen, the current ambient temperature of the screen is read by the temperature sensor in the screen IC, and the VCOM voltage compensation value under the combined effect of the basic temperature compensation data and the calibration temperature compensation data at the current temperature is obtained to control the display screen.

[0018] The VCOM voltage compensation value under the combined effect of basic temperature compensation data and calibration temperature compensation data is

[0019] △D if =△D x +△D i Or △D if =D 室温 *β x *α i .

[0020] The advantages of this invention are as follows: considering the influence of temperature on the reference OLED and the performance differences between each screen, basic temperature compensation data and calibration temperature compensation data are set respectively. The VCOM voltage corresponding to brightness adjustment is adjusted by using the two temperature compensation data together, so that the brightness display difference between different OLEDs is reduced. In addition, this method can enable multiple OLED displays with the same target brightness to share a set of temperature compensation data, which indirectly improves the efficiency of brightness compensation based on temperature compensation feedback. Attached Figure Description

[0021] The following is a brief explanation of the contents of each of the accompanying drawings and the markings in the drawings:

[0022] Figure 1 This is a flowchart illustrating the principle of brightness compensation in this invention.

[0023] Figure 2 This is a flowchart illustrating the generation process of the VCOM compensation data LUT table in this invention.

[0024] Figure 3 This invention illustrates the relationship between the VCOM register value and temperature under the same brightness conditions. Detailed Implementation

[0025] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and the description of the preferred embodiments.

[0026] like Figure 1 The diagram shown is a flowchart of the brightness compensation implementation of this application, and its specific scheme includes the following steps;

[0027] 1) Obtain the current ambient temperature through the temperature sensor inside the display IC chip;

[0028] Select the appropriate VCOM compensation sub-table from the pre-calibrated LUT table according to actual needs; different VCOM compensation sub-tables include: compensation sub-tables obtained by linear interpolation, compensation sub-tables obtained by second-order function expression, compensation sub-tables obtained by third-order function expression, compensation sub-tables obtained by higher-order function expression, etc.

[0029] Multiple compensation sub-tables are provided in the early stages of design to match the actual display effect of OLED as closely as possible.

[0030] 2) Obtain the VCOM compensation value ΔD at the current temperature based on the selected VCOM compensation sub-table. if =△D x +△D i Or △D if =D 室温 *β x *α i ;

[0031] 3) Send the corresponding VCOM voltage compensation value to the voltage driver;

[0032] 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.

[0033] The LUT lookup table includes the following parts:

[0034] The baseline temperature-compensated data consists of the difference (or scaling factor) between the VCOM voltage values ​​at different temperatures achieving the same brightness and the VCOM voltage values ​​at room temperature (e.g., 25℃), and the calibration temperature-compensated data consists of the difference (or scaling factor) between the VCOM voltage values ​​of different screens at room temperature (e.g., 25℃) and the baseline temperature-compensated VCOM voltage values ​​at room temperature (e.g., 25℃), as detailed in Table 1 below:

[0035]

[0036]

[0037] In this application, the LUT table refers to the pre-calibrated baseline temperature compensation data and calibration temperature compensation data for different displays and at different temperatures. Its principle is as follows: Figure 2 As shown,

[0038] The data in the LUT tables above were obtained through testing and data processing, as follows:

[0039] 1) Set the desired target brightness at room temperature, select a reference OLED, and obtain the register value D corresponding to the VCOM voltage value of the reference OLED at the target brightness and room temperature. 室温 ;

[0040] In this application, a reference OLED is selected or set. The reference OLED is defined as the register value corresponding to the VCOM voltage value at room temperature that corresponds to the set target brightness. 室温 Other OLEDs: The register value corresponding to the VCOM voltage value that corresponds to the set target brightness at room temperature is Dx.

[0041] 2) By testing the register value D corresponding to the VCOM voltage required to achieve the target brightness at different temperatures in a high and low temperature test chamber. i The Di corresponding to different i is the register value Di for temperature i.

[0042] A set of unprocessed VCOM values ​​(D1, D2, D3, ..., D) is obtained. m );

[0043] 3) Select an appropriate data processing method to obtain the VCOM compensation value at each temperature relative to room temperature (e.g., 25℃). This can be achieved using linear interpolation, quadratic function expressions, cubic function expressions, or fitting higher-order function expressions. The VCOM compensation value can be the difference ΔD between the register value corresponding to VCOM at each room temperature and the register value corresponding to VCOM at room temperature. i It can also be the scaling factor value α. i This yields the basic temperature compensation data;

[0044] 4) Linear interpolation method: y = ax + b, requires two sets of (x, y) to solve for a and b;

[0045] 5) Quadratic function expression method: y=ax2+bx+c, three sets of (x,y) are needed to solve for a,b,c;

[0046] 6) Cubic function expression method: y=ax3+bx2+cx+d, four sets of (x,y) are needed to solve for a,b,c,d;

[0047] 7) Quadratic function expression: y = ax 4 The expression +bx³ + cx² + dx + e requires five sets of (x, y) to solve for a, b, c, d, e.

[0048] 8) Example: When testing basic temperature compensation data, to save time and reduce workload, the test temperature range is -40℃ to 70℃, with one data point tested every 10℃. In actual temperature compensation, temperature compensation is required every 1 / 2 / 3 / 4 / 5℃. Therefore, it is necessary to use a formula to calculate the VCOM compensation value difference ΔD at other temperatures. i or α iA curve is simulated using partial temperature data, and then all the data is derived from this curve.

[0049] Each screen needs to undergo OTP (Over-The-Air) testing. During OTP, the register value D corresponding to the VCOM voltage required for each screen to reach the target brightness at room temperature (e.g., 25°C) is obtained. x The difference ΔD between the register value D corresponding to VCOM at room temperature (e.g., 25°C) and the baseline temperature-compensated data of the reference OLED is calculated. x Or the scaling factor β x The calibration temperature compensation data is obtained; α i : Register value D corresponding to the VCOM value obtained at different temperatures of the reference OLED i Register value D corresponding to the VCOM value at room temperature 室温 The ratio, i.e., α i =D i / D 室温 ;

[0050] β x : Register value D corresponding to the VCOM value obtained by other OLEDs at room temperature x Register value D corresponding to the VCOM value of the reference OLED at room temperature 室温 The ratio, i.e., β x =D x / D 室温 ;

[0051] △D x , △D i These are all register values, and the register values ​​store the VCOM voltage compensation values;

[0052] 9) The final VCOM compensation value is composed of two parts: the basic temperature compensation data and the calibration temperature compensation data.

[0053] △D if =△D x +△D i Or △D if =D 室温 *β x *α i ;

[0054] By conducting tests on multiple sets of data, basic temperature compensation data and calibration temperature compensation data corresponding to different OLEDs at different temperatures can be obtained, thus forming a LUT table.

[0055] The LUT table obtained through the above experimental calibration will be pre-stored or saved in the memory and registers of the IC chip, so that the corresponding VCOM voltage value can be obtained in time when the display is working, thereby realizing the adjustment of the brightness of the display.

[0056] In this application, the reference 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 室温 D i i is the temperature value, D i With D 室温 The reference temperature compensation data △D was obtained by comparison. i or α i ;

[0057] Other OLEDs only require testing the register value D corresponding to the VCOM value at room temperature. x and compared with the D of the benchmark OLED 室温 By comparison, we obtain △D x or β x .

[0058] like Figure 3 The figure shows the relationship between VCOM register values ​​and temperature at the same brightness, achieved using linear interpolation and quadratic function expressions. It illustrates the relationship between register values ​​and temperature at different temperatures. With the same test data, different compensation algorithms yield different compensated brightness values. Therefore, a suitable compensation algorithm needs to be matched to the actual display effect of the OLED. This approach uses limited test data to fit and form a curve. Following the curve, as many VCOM values ​​as possible for each temperature can be obtained without requiring a large amount of test data. This application can achieve relatively accurate acquisition of VCOM data at temperature points using limited data fitting.

[0059] In another preferred embodiment, this application also provides a method for calculating basic temperature compensation data. The basic temperature compensation data processing is to calculate the difference ΔDi between the register value corresponding to VCOM at each temperature and the register value corresponding to VCOM at the adjacent temperature, or it can be a scaling factor value αi, to obtain the basic temperature compensation data. The adjacent temperature is defined as follows: the adjacent temperature below room temperature (e.g., 25°C) is the next temperature point higher than it, and the adjacent temperature above room temperature (e.g., 25°C) is the previous temperature point lower than it.

[0060] This application reduces the display effect differences among multiple OLED displays and improves the brightness compensation effect of OLED displays by storing the relative differences (or scaling factors) of the VCOM registers at various temperatures relative to room temperature under the same brightness. Furthermore, by adding calibration temperature compensation data composed of the difference (or scaling factor) between the VCOM register values ​​of each OLED display and the base temperature compensation data at room temperature (e.g., 25°C), the display effect differences between different OLED displays are further reduced, enhancing the brightness compensation effect. The LUT table contains multiple selectable VCOM compensation sub-tables, allowing the selection of an appropriate VCOM compensation sub-table for brightness compensation based on actual needs, aiming to achieve the optimal brightness compensation effect.

[0061] The technical effects of this application include:

[0062] (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 constructs basic temperature compensation data by storing the relative difference (or proportional coefficient) of each temperature under the same brightness relative to the VCOM register under room temperature. This can reduce the difference in display effect of multiple OLED displays and improve the brightness compensation effect of OLED displays.

[0063] (2) By increasing the calibration temperature compensation data, which is composed of the difference (or scaling factor) between the VCOM voltage value of each OLED display and the VCOM voltage value at room temperature (e.g., 25°C) of the basic temperature compensation data, the difference in display effect between different OLED displays is further reduced and the brightness compensation effect is enhanced.

[0064] (3) The LUT table contains a variety of optional VCOM compensation sub-tables. You can select the appropriate VCOM compensation sub-table for brightness compensation according to actual needs in order to achieve the best brightness compensation effect.

[0065] (4) The display effects of OLED displays vary. The VCOM value required to achieve the same display brightness at the same temperature is different. Therefore, the original temperature-based brightness compensation method may not be applicable to all displays. However, this method can enable multiple OLED displays with the same target brightness to share a set of temperature compensation data, which indirectly improves the efficiency of temperature-based brightness compensation.

[0066] Obviously, the specific implementation of this invention is not limited to the above-described methods. Any non-substantial improvements made using the inventive concept and technical solution of this invention are within the protection scope of this invention.

Claims

1. A method of compensating for display brightness based on temperature feedback, characterized by: The method comprises the following steps: Obtaining a reference OLED corresponding to the basic temperature compensation data ΔD for temperature changes i ; calculating calibration temperature compensation data ΔD for each OLED with respect to the reference OLED for its own parameter difference x ; The OLED display is compensated by the basic temperature compensation data ΔD corresponding to the temperature of the OLED display i and the calibration temperature compensation data ΔD x in a common compensation mode. Basic temperature compensation data ΔD i The acquisition method comprises: 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 corresponding to the voltage value 室温 ; For a reference OLED display, the register value D corresponding to the VCOM voltage value required to reach the target brightness at different temperatures is tested i where i is the temperature. The reference OLED display is calculated to obtain the VCOM compensation value at different temperatures relative to room temperature, thereby obtaining the basic temperature compensation data ΔD i ; The VCOM compensation value of the reference OLED display at different temperatures relative to the room temperature is calculated by using linear interpolation method, quadratic function expression, cubic function expression, or fitting higher order function expression method, and the difference value ΔD of the register value corresponding to the VCOM of the reference OLED at each temperature relative to the register value corresponding to the VCOM at the room temperature is calculated i or the proportional factor value α i ; The calibration temperature compensation data calculation method is as follows: Obtaining the register value D corresponding to the VCOM voltage value required by each OLED to reach the target brightness at room temperature x , obtaining the register value D corresponding to the VCOM at room temperature of the basic temperature compensation data by calculating the difference ΔD x or the proportion factor β x of the register value D corresponding to the VCOM at room temperature of the basic temperature compensation data 室温 , obtaining the calibration temperature compensation data; When controlling the brightness of each screen, the current ambient temperature of the screen is read by the temperature sensor in the screen IC, and the VCOM voltage compensation value under the joint action of the basic temperature compensation data and the calibration temperature compensation data at the current temperature is obtained to control the display screen; The VCOM voltage compensation value under the joint action of the basic temperature compensation data and the calibration temperature compensation data is △D if = △D x + △D i or △D if = D 室温 * β x * α i ; The reference OLED display is a pre-selected calibrated OLED display; Obtaining a plurality of basic temperature compensation data △D corresponding to temperatures through experiments i Then, a fitting curve between the temperature and the basic temperature compensation data △D is obtained through a linear interpolation method, a quadratic function expression, a cubic function expression, or a method of fitting a higher order function expression i ; and the basic temperature compensation data △D of the remaining temperatures not obtained through experiments is obtained based on the fitting curve i ; The voltage compensation values corresponding to different temperatures are stored in the display IC in the form of a VCOM compensation sub-table.

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