Temperature sensor calibration and external temperature compensation method of OLED micro display

Abstract

The invention relates to the technical field of OLED micro-displays, and discloses a temperature sensor calibration and external temperature compensation method for an OLED micro-display, and the method comprises a temperature compensation parameter storage module which is used for storing the temperature calibration data of the OLED micro-display through a one-time programmable memory OTP. According to the temperature sensor calibration and external temperature compensation method for the OLED micro-display, the actual working temperature Tactual is calculated by using the current temperature register value REG1 measured by the temperature sensor and factory calibration data T0 and REG0, the brightness change is compensated by adjusting the common voltage Vcom in real time, and the temperature of the OLED micro-display is compensated by combining a temperature compensation formula. The brightness of the display is accurately controlled by adjusting the electric field intensity, the Vcom is improved in a low-temperature environment to compensate brightness reduction, and the Vcom is reduced in a high-temperature environment to prevent excessive light emission or thermal damage, so that the problem of inconsistent display effects in long-term use is solved, and the user experience is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of OLED microdisplays, and in particular to a temperature sensor calibration and external temperature compensation method for an OLED microdisplay. Background Art

[0002] OLED microdisplay is a small display based on organic light-emitting diode technology. Unlike traditional LCD displays, OLED displays do not require a backlight source. Due to their self-luminous properties, OLED displays are more vivid, have higher contrast, and have a faster response time. OLED microdisplays are usually small in size and high in resolution, and are widely used in various small display devices, such as smart glasses, virtual reality helmets, augmented reality devices, micro projectors, wearable devices, etc.

[0003] There is a close relationship between the performance of OLED (Organic Light Emitting Diode) displays and temperature changes, especially in terms of display brightness, color accuracy and long-term display stability. Temperature changes can directly affect the performance of OLED displays, resulting in significant deviations. This phenomenon is mainly due to the working principle of OLED displays and the characteristics of the organic materials used. In OLED displays, each pixel emits light from organic materials, and the luminous efficiency of these materials is significantly affected by temperature changes. When the temperature rises, the photoelectric conversion efficiency of OLED materials decreases, resulting in reduced brightness. Conversely, when the temperature decreases, the luminous efficiency of OLED materials may increase, resulting in excessive brightness. Therefore, temperature fluctuations will directly affect the brightness stability of the display, making the display effect inconsistent. In order to ensure that OLED displays can provide stable display effects under different temperature environments, temperature changes must be effectively compensated. However, in actual applications, OLED displays are usually in dynamic environments with large temperature changes, especially some wearable devices, automotive displays, etc., where the ambient temperature may fluctuate frequently. Therefore, traditional temperature compensation methods are usually based on static calibration data for compensation, which does not dynamically respond to temperature changes and fails to adjust the display effect in real time. The static compensation scheme is effective in the short term, but in the long term, as the temperature environment continues to change, the static compensation scheme will become ineffective, resulting in inconsistent display effects. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the shortcomings of the prior art, the present invention provides a method for temperature sensor calibration and external temperature compensation of an OLED microdisplay, which solves the problem that the performance of the OLED display is affected by temperature changes, and the traditional static temperature compensation method cannot dynamically respond to ambient temperature fluctuations, resulting in inconsistent display effects during long-term use.

[0006] (II) Technical solution

[0007] To achieve the above object, the present invention provides the following technical solution: a temperature sensor calibration method for an OLED microdisplay, comprising: a temperature compensation parameter storage module, wherein the temperature compensation parameter storage module is used to store temperature calibration data of the OLED microdisplay through a one-time programmable memory OTP; the temperature calibration data storage steps of the temperature compensation parameter storage module are as follows:

[0008] Step 1: When the display is shipped from the factory, the temperature sensor is usually connected to the microcontroller unit MCU through the I2C protocol. The microcontroller unit MCU sends a read command to request to obtain the current temperature data from the temperature sensor. The temperature data sends the temperature information to the microcontroller unit MCU in the form of a digital signal, and writes these data into the one-time programmable memory OTP for storage;

[0009] Step 2: The stored data includes the temperature value and the register value of the sensor. The temperature value is in °C, and the register value of the sensor has no unit, but is proportional to the temperature value. The formula is as follows: temperature value = register value * 0.561-57;

[0010] Step 3: After the calibration data is stored, each time the display is started, the microcontroller unit MCU reads the temperature calibration data and register value REG0 in the one-time programmable memory OTP through the IIC bus;

[0011] Step 4: Read the current temperature register value REG1 and use the following formula to get the calibrated temperature value:

[0012] T1=(REG1+OFFSET)×0.561-57

[0013]

[0014] 0.561 and 57 in the above formula are the parameters in the previous temperature calculation formula. Set T0' to the expected temperature value calculated by REG0 and the relevant calibration formula. Set T1' to the expected temperature value calculated by REG1 and the calibration formula under this value. Set T0 to the standard operating temperature, and compare T0' with T0 to calculate the offset OFFSET. By adding OFFSET to T1', the actual operating temperature T1 of the display can be obtained.

[0015] Preferably, the temperature calibration data storage structure of the temperature compensation parameter storage module includes:

[0016] Gamma storage location: MicroOLED uses 9 / 10-bit gamma data storage to save gamma data, and stores gamma calibration data separately according to grayscale values ​​and different colors (red, green, and blue);

[0017] Data storage format: The red, green, and blue gamma data corresponding to the grayscale value are stored in different byte positions. The specific storage format is as follows: Figure 3 .

[0018] Preferably, the one-time programmable memory OTP is a non-volatile memory, and its data cannot be changed once written.

[0019] Preferably, the specific operation flow of the one-time programmable memory OTP is as follows:

[0020] Writing temperature calibration data at the factory: During the device manufacturing stage, the calibration data of the temperature sensor is written into the one-time programmable memory OTP;

[0021] Reading data at each startup: Each time the OLED display is started, the microcontroller unit MCU reads the temperature calibration data in the one-time programmable memory OTP through the IIC bus. After reading the data, the microcontroller unit MCU calculates the compensation value based on the current temperature value and the stored calibration data;

[0022] Temperature compensation calculation and application: The microcontroller unit MCU adjusts the operating parameters of the display in real time according to the compensation formula to ensure stable brightness.

[0023] Preferably, the one-time programmable memory OTP is a non-volatile memory, which ensures that data is not lost in the event of a power outage, so that the microcontroller unit MCU can read accurate calibration data each time it is started.

[0024] An external temperature compensation method for an OLED microdisplay, the external temperature compensation method comprising: determining a temperature compensation formula and applying temperature compensation;

[0025] The steps to determine the temperature compensation formula include:

[0026] Step 1: Place the microdisplay on the test platform and connect the probe and communication line;

[0027] Step 2: Set the temperature to -40 degrees Celsius. After it stabilizes, send a command through the computer to adjust VCOM so that the brightness level remains at the preset value, and record the VCOM and temperature values ​​at this time;

[0028] Step 3: Repeat step 2 and gradually adjust the temperature in the test box to -35℃, -30℃, 60℃, and 65℃. After each temperature adjustment, wait for the system to reach a stable state. At each temperature point, repeat step 2 to adjust Vcom to keep the brightness of the display stable at the target value, and record the current Vcom value and temperature value.

[0029] Step 4: Use the fitting tool to perform quadratic function fitting on VCOM and the corresponding temperature value. Use the quadratic function fitting algorithm to find the optimal fitting curve. After the fitting is completed, a formula is obtained. For our existing products, the formula after fitting is as follows:

[0030] Vcom=0.00012T 2 -0.019T+0.44

[0031] T is the test temperature, and Vcom is the Vcom value required to keep the brightness stable at this temperature. So far, the temperature compensation formula has been determined;

[0032] The steps to apply temperature compensation include:

[0033] Step 1: Calculate the current actual temperature value through the formula. To ensure stability, window translation filtering can be performed. The formula is as follows:

[0034] T1=(REG1+OFFSET)×0.561-57

[0035] in

[0036] Among them, REG1 is the temperature register value, T0 and REG0 are the temperature value and register value in the one-time programmable memory OTP;

[0037] Step 2: Calculate the Vcom value that should be output according to the temperature, that is, calculate according to the formula determined in "Determination of temperature compensation formula";

[0038] Step 3: The calculated Vcom value is passed to the display driver circuit through the IIC bus, and the Vcom value of the display is updated in real time. The driver chip receives the command and adjusts the common voltage Vcom of the display to the new set value. The driver circuit adjusts the working state of the display according to the Vcom value.

[0039] Preferably, the Vcom value directly affects the brightness of the display. By adjusting the Vcom value, the electric field strength of the display can be adjusted, thereby controlling the luminous brightness.

[0040] Preferably, the operation of using the fitting tool to perform quadratic function fitting on VCOM and the corresponding temperature value is as follows:

[0041] Enter temperature (T) as the independent variable and VCOM as the dependent variable into the fitting tool, select the quadratic function model, that is: VCOM = aT2 + bT + c, run the fitting algorithm in the tool, and calculate the coefficients a, b, and c of the best fitting curve. Take the MATLAB mathematical calculation tool as an example:

[0042] Assuming the data is stored in variables T and VCOM, then:

[0043] coefficients=polyfit(T,VCOM,2);

[0044] a=coefficients(1);

[0045] b = coefficients(2);

[0046] c = coefficients(3);

[0047] Substitute the fitted coefficients into the quadratic function model to obtain the compensation formula:

[0048] Vcom=0.00012T 2 -0.019T+0.44

[0049] Substitute the known data points into the fitting formula, calculate the fitting value, compare it with the experimental value, and check the fitting accuracy.

[0050] Preferably, there is a linear relationship between the output register value of the temperature sensor and the actual temperature, and the current register value REG1 can be converted into the actual temperature value through the calibration data REG0 and T0.

[0051] Preferably, in the temperature compensation application process, the microcontroller unit MCU works closely with the temperature sensor to ensure that the brightness of the display remains stable under different temperature conditions through a series of precise calculation and adjustment steps. The following are the specific steps in the temperature compensation process of the OLED microdisplay:

[0052] Step 1: During the working process of the display, the temperature sensor continuously monitors the ambient temperature and converts the collected temperature signal into a digital form, usually a register value REG. The register value has no unit, but is in a certain proportional relationship with the temperature. It can be converted into an actual temperature value through a predetermined conversion formula. The microcontroller unit MCU receives the register value sent by the temperature sensor through the IIC bus. After receiving the data, the microcontroller unit MCU will convert the register value into the actual ambient temperature value according to a preset temperature conversion formula, such as temperature value = register value * 0.561-57. In this way, the microcontroller unit MCU can accurately obtain the current ambient temperature and perform subsequent compensation calculations based on this;

[0053] Step 2: The microcontroller unit MCU will compare the currently acquired temperature value T1 with the standard operating temperature T0 of the display. If there is a difference between the two, the microcontroller unit MCU will calculate a temperature deviation value △T = T1-T0. This temperature deviation value represents the change of the current ambient temperature relative to the standard operating temperature. After calculating the temperature deviation, the microcontroller unit MCU will use the deviation value to decide how to adjust the operating parameters of the display;

[0054] Step 3: During the operation of the display, the microcontroller unit MCU will record historical temperature data. This data may include the temperature change record of the display since it was enabled, ensuring that the microcontroller unit MCU can obtain the change trend of the ambient temperature. The historical data is stored in the memory of the microcontroller unit MCU, usually a circular cache, for future predictions. Based on the recorded historical temperature data, the microcontroller unit MCU can analyze the temperature change trend. For example, the temperature may show an upward trend in the past period of time, or the change is relatively stable in certain periods of time. The microcontroller unit MCU uses this data to estimate the temperature change pattern, so as to better predict the future temperature trend. By analyzing the historical temperature change trend, the microcontroller unit MCU can predict the temperature change in the future period of time, which enables the microcontroller unit to pre-adjust the Vcom value in advance to avoid the instability of the display brightness caused by temperature fluctuations;

[0055] Step 4: The microcontroller unit MCU uses linear regression to predict the temperature change in the future. If the system detects that the temperature is gradually rising or falling, the microcontroller unit MCU will make Vcom adjustments in advance. This prediction can effectively avoid delayed response caused by temperature changes, making the brightness adjustment of the display smoother and more timely. According to the prediction of the temperature change trend, the microcontroller unit MCU will adjust the Vcom value in advance. If the temperature is predicted to rise in the future, the microcontroller unit MCU will increase the Vcom value accordingly; if the temperature is expected to drop, the Vcom value will be reduced. The purpose of adjusting the Vcom value in advance is to ensure that the display brightness is stable before the actual temperature change occurs.

[0056] Step 5: The microcontroller unit MCU will calculate a compensation value based on the temperature deviation △T and the historical temperature change trend. This compensation value determines the adjustment range of the Vcom value. Generally, the larger the temperature deviation, the larger the adjustment range of the Vcom value. The microcontroller unit MCU adjusts the Vcom value of the display in real time according to the calculated compensation value. If the temperature is high, the microcontroller unit MCU will reduce the Vcom value to avoid excessive display brightness; if the temperature is low, the Vcom value will be increased to maintain a stable brightness. After each adjustment, the microcontroller unit MCU will send the new Vcom value to the display driver circuit through the IIC bus to ensure the stability of the display brightness;

[0057] Step 6: After each Vcom value adjustment, the microcontroller unit MCU will monitor the brightness changes of the display. If the brightness is stable, the compensation adjustment process is successful; if the brightness still fluctuates, the microcontroller unit MCU will continue to adjust the Vcom value until the display brightness is stable. With the accumulation of experience during use, the microcontroller unit MCU can continuously optimize the compensation algorithm based on feedback data. By analyzing the performance under different environmental conditions, the microcontroller unit MCU can further improve the accuracy and efficiency of temperature compensation.

[0058] (III) Beneficial effects

[0059] Compared with the prior art, the present invention provides a method for calibrating a temperature sensor and external temperature compensation for an OLED microdisplay, which has the following beneficial effects:

[0060] 1. The temperature sensor calibration and external temperature compensation method of the OLED micro display uses the current temperature register value REG1 measured by the temperature sensor and the factory calibration data T0 and REG0 to calculate the actual operating temperature Tactual, and compensates for the change in brightness by adjusting the common voltage Vcom in real time. Combined with the temperature compensation formula, the luminous brightness of the display is accurately controlled by adjusting the electric field strength. In a low temperature environment, Vcom is increased to compensate for the decrease in brightness, and in a high temperature environment, Vcom is reduced to prevent excessive luminescence or thermal damage, which solves the problem of inconsistent display effects in long-term use and improves user experience.

[0061] 2. The temperature sensor calibration and external temperature compensation method of the OLED microdisplay establishes the correspondence between the register value and the actual temperature through temperature calibration based on linear interpolation, and uses the temperature compensation formula generated by the quadratic function fitting algorithm to provide the display with a wide range of temperature adaptability. Even in a wide temperature range of -40°C to 65°C, the display can adjust its brightness and color output according to the real-time ambient temperature. This automatic adjustment function allows the display to be used in a variety of complex environments, such as extremely cold areas, tropical high temperature environments or industrial equipment, which significantly enhances the environmental adaptability of the display and expands its application scenarios.

[0062] 3. The temperature sensor calibration and external temperature compensation method of the OLED microdisplay monitors the operating temperature of the display in real time and dynamically adjusts the Vcom value to prevent performance degradation or component damage caused by overheating or low temperature. In addition, the use of OTP memory ensures the long-term stability of the calibration data, and the MCU can accurately read and apply this data each time it is started. This dual protection mechanism significantly reduces the failure rate of the device, extends the service life of the display, and improves overall reliability.

[0063] 4. The temperature sensor calibration and external temperature compensation method of the OLED microdisplay uses a temperature sensor to monitor the working temperature in real time, and adjusts the Vcom value according to the compensation formula to dynamically adjust the brightness output of each color channel. Through this technology, the display can maintain color accuracy and consistency at different temperatures, avoid color drift or display distortion caused by temperature changes, and provide users with a better visual experience.

[0064] 5. The temperature sensor calibration and external temperature compensation method of the OLED microdisplay can accurately adjust the Vcom value of the display under different temperature conditions by real-time monitoring of temperature and accurate calculation of temperature deviation, thereby ensuring the stability of display brightness. This precise temperature compensation can effectively eliminate the display brightness fluctuation caused by temperature changes and improve the stability and consistency of the display effect.

[0065] 6. The temperature sensor calibration and external temperature compensation method of the OLED microdisplay. By analyzing the historical temperature data, the microcontroller unit (MCU) can predict the future temperature change trend (such as the temperature gradually rising or falling) and adjust the Vcom value in advance. This prediction mechanism can effectively avoid the delayed response caused by temperature fluctuations, so that the display can adjust the brightness before the temperature changes, ensuring that the brightness adjustment of the display is smoother and more timely, and reducing the impact of temperature changes on display quality.

[0066] 7. The temperature sensor calibration and external temperature compensation method of the OLED microdisplay. Through real-time and intelligent temperature compensation, the brightness control of the OLED display becomes more precise, which means that the display can avoid unnecessary high power consumption. For example, in a low temperature environment, the MCU can moderately increase the Vcom value to maintain brightness, and in a high temperature environment, it can prevent excessive power consumption by reducing the Vcom value. This efficient energy management can extend the service life of the display, reduce energy consumption, and improve the overall efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 A schematic diagram of a temperature sensor calibration method for an OLED microdisplay proposed by the present invention;

[0068] Figure 2 A schematic diagram of an external temperature compensation method for an OLED microdisplay proposed by the present invention;

[0069] Figure 3 This is a schematic diagram of the data storage format of a temperature sensor calibration and external temperature compensation method for an OLED microdisplay proposed by the present invention. DETAILED DESCRIPTION

[0070] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0071] See also Figure 1 - Figure 3 , a temperature sensor calibration method for an OLED microdisplay, comprising:

[0072] A temperature compensation parameter storage module, which is used to store temperature calibration data of the OLED microdisplay through a one-time programmable memory OTP. The stored calibration data mainly includes the corresponding relationship between the temperature value and the corresponding sensor reading;

[0073] The steps for storing the temperature calibration data of the temperature compensation parameter storage module are as follows:

[0074] Step 1: When the display is shipped from the factory, the temperature sensor is usually connected to the microcontroller unit MCU through the I2C protocol. The microcontroller unit MCU sends a read command to request to obtain the current temperature data from the temperature sensor. The temperature data sends the temperature information to the microcontroller unit MCU in the form of a digital signal, and writes these data into the one-time programmable memory OTP for storage;

[0075] Step 2: The stored data includes the temperature value and the register value of the sensor. The temperature value is in °C, and the register value of the sensor has no unit, but is proportional to the temperature value. The formula is as follows: temperature value = register value * 0.561-57;

[0076] Step 3: After the calibration data is stored, each time the display is started, the microcontroller unit MCU reads the temperature calibration data and register value REG0 in the one-time programmable memory OTP through the IIC bus;

[0077] Step 4: Read the current temperature register value REG1 and use the following formula to get the calibrated temperature value:

[0078] T1=(REG1+OFFSET)×0.561-57

[0079]

[0080] 0.561 and 57 in the above formula are parameters in the previous temperature calculation formula. Set T0' to the expected temperature value calculated by REG0 and the relevant calibration formula. Set T1' to the expected temperature value calculated by REG1 and the calibration formula under this value. Set T0 to the standard operating temperature, T0 is 25℃, and compare T0' with T0 to calculate the offset OFFSET. By adding OFFSET to T1', the actual operating temperature T1 of the display can be obtained. The offset OFFSET is calculated to find the difference between the actual temperature and the expected temperature of the display. Since the measurement of the temperature sensor may have errors or other factors, the temperature value during calibration, that is, the temperature T0 recorded at the factory, may deviate from the temperature value T0' calculated based on the formula. Then use OFFSET and T1' to calculate the actual value T1 of the current temperature. The actual temperature T1 can be calculated by the known OFFSET and T1'. Assuming that T1' is the expected temperature value calculated by the current sensor REG1 and the calibration data REG0, the actual temperature T1 can be calculated as follows: T1 = T1' + OFFSET, that is, T1' is the expected temperature calculated based on the current sensor value REG1 and the calibration value REG0, and OFFSET is the error adjustment value during factory calibration. By adding OFFSET to T1', the actual operating temperature T1 of the display can be obtained.

[0081] The temperature calibration data storage structure of the temperature compensation parameter storage module includes:

[0082] Gamma storage location: MicroOLED uses 9 / 10-bit gamma data storage to save gamma data, and stores gamma calibration data separately according to grayscale values ​​and different colors (red, green, and blue);

[0083] Data storage format: The red, green, and blue gamma data corresponding to the grayscale value are stored in different byte positions. The specific storage format is as follows: Figure 3 , since the temperature sensor calibration data is stored in this structure, 3 bytes of space can be saved for storing temperature data. In the Gamma data structure of the OLED display, the smallest storage unit is 1 byte, and the temperature calibration data (i.e., the temperature value and the sensor register value) originally needs to be allocated space separately. If these temperature data are embedded in the Gamma data structure, some free bytes under the grayscale value (such as the placeholder represented by the "XX" value) can be used to save the 3 bytes of extra space that would otherwise be required. This is because not every position of the bytes in the Gamma data structure is completely filled, and the temperature data can be embedded in it through clever design. Specifically, if the Gamma data has redundant bits or bytes under certain grayscale values (For example, the low 8 bits are stored as empty), these empty bits can be occupied by temperature calibration data, thereby avoiding the allocation of additional storage space for temperature data. For example, some bytes in the Gamma data of grayscale value 0 are free (such as "available 8 bits"). At this time, the temperature calibration data can be directly stored in these free bytes, so there is no need to allocate an additional 3 bytes for storing temperature data, saving storage space. The temperature sensor calibration data is embedded in the storage structure of the Gamma data, and the existing storage space is used to store the temperature data instead of allocating space for it separately, which can save 3 bytes of storage space. This storage optimization method helps to achieve efficient storage of temperature data and display calibration data under limited storage resources.

[0084] One-time programmable memory OTP is a non-volatile memory, and its data cannot be changed once written. It is suitable for storing temperature calibration data to ensure that the temperature compensation data of each display is unique and stable. The working principle of one-time programmable memory OTP is similar to that of ordinary memory, but its important feature is "one-time write". Once the data is written into the one-time programmable memory OTP, it will remain unchanged forever until the device is disassembled or damaged. Due to its unchangeable characteristics, the one-time programmable memory OTP is very suitable for storing data that needs to remain stable for a long time, such as the calibration data of the temperature sensor. In the present invention, the one-time programmable memory OTP is used to save the temperature calibration data of the display.

[0085] The specific operation process of the one-time programmable memory OTP is as follows:

[0086] Temperature calibration data is written at the factory: During the device manufacturing stage, the calibration data of the temperature sensor is written into the one-time programmable memory OTP. Typically, this data includes the mapping relationship between the specific temperature of each display and the sensor reading;

[0087] Reading data at each startup: Each time the OLED display is started, the microcontroller unit MCU reads the temperature calibration data in the one-time programmable memory OTP through the IIC bus. After reading the data, the microcontroller unit MCU calculates the compensation value based on the current temperature value and the stored calibration data;

[0088] Temperature compensation calculation and application: The microcontroller unit MCU adjusts the operating parameters of the display in real time according to the compensation formula to ensure stable brightness. This process is achieved through communication with the display driver via the IIC bus.

[0089] The one-time programmable memory OTP is a non-volatile memory that ensures that data is not lost in the event of a power outage, so that the microcontroller unit MCU can read accurate calibration data each time it is started.

[0090] An external temperature compensation method for an OLED microdisplay, the external temperature compensation method comprising: determining a temperature compensation formula and applying temperature compensation;

[0091] The steps to determine the temperature compensation formula include:

[0092] Step 1: Place the microdisplay on the test platform and connect the probe and communication line;

[0093] Step 2: Set the temperature to -40 degrees Celsius. After it stabilizes, send a command through the computer to adjust VCOM so that the brightness level remains at the preset value, and record the VCOM and temperature values ​​at this time;

[0094] Step 3: Repeat step 2, and gradually adjust the temperature in the test box to -35℃, -30℃, 60℃, and 65℃. After each temperature adjustment, wait for the system to reach a stable state. At each temperature point, repeat the operation of step 2, adjust Vcom to keep the brightness of the display stable at the target value, and record the current Vcom value and temperature value. By recording Vcom and the corresponding temperature values ​​at different temperatures, a Vcom and temperature data table covering the operating temperature range can be formed, providing sufficient data support for the subsequent fitting formula;

[0095] Step 4: Use the fitting tool to perform quadratic function fitting on VCOM and the corresponding temperature value. Use the quadratic function fitting algorithm to find the optimal fitting curve. After the fitting is completed, a formula is obtained. For our existing products, the formula after fitting is as follows:

[0096] Vcom=0.00012T 2 -0.019T+0.44

[0097] T is the test temperature, and Vcom is the Vcom value required to keep the brightness stable at this temperature. So far, the temperature compensation formula has been determined;

[0098] The steps to apply temperature compensation include:

[0099] Step 1: Calculate the current actual temperature value through the formula. To ensure stability, window translation filtering can be performed. The formula is as follows:

[0100] T1=(REG1+OFFSET)×0.561-57

[0101] in

[0102] Among them, REG1 is the temperature register value, T0 and REG0 are the temperature value and register value in the one-time programmable memory OTP;

[0103] Step 2: Calculate the Vcom value that should be output according to the temperature, that is, calculate according to the formula determined in "Determination of temperature compensation formula";

[0104] Step 3: The calculated Vcom value is transmitted to the display driver circuit through the IIC bus, and the Vcom value of the display is updated in real time. The driver chip receives the command and adjusts the common voltage Vcom of the display to the new set value. The driver circuit adjusts the working state of the display according to the Vcom value. By updating the Vcom value in real time, the display can automatically adjust the brightness according to the current working temperature to ensure a stable display effect.

[0105] Repeat the above steps at regular intervals to achieve the temperature compensation function. Since the ambient temperature may change at any time, temperature compensation is not a one-time operation, but a continuous process. This process ensures that the display can respond to temperature changes in real time and dynamically adjust the brightness to ensure that the OLED display can always provide a stable display effect in different temperature environments. The Vcom value directly affects the brightness of the display. By adjusting the Vcom value, the electric field strength of the display can be adjusted to control the luminous brightness. In a low temperature environment, the luminous efficiency of the OLED material decreases, and it is necessary to increase Vcom to compensate for the decrease in brightness. Therefore, recording the Vcom value at this time helps to establish the corresponding relationship between brightness and temperature.

[0106] The operation of using the fitting tool to fit the quadratic function of VCOM and the corresponding temperature value is as follows:

[0107] Enter temperature (T) as the independent variable and VCOM as the dependent variable into the fitting tool, and select the quadratic function model, that is: VCOM = aT 2 +bT+c, run the fitting algorithm in the tool to calculate the coefficients a, b, and c of the best fitting curve. Take MATLAB mathematical calculation tool as an example:

[0108] Assuming the data is stored in variables T and VCOM, then:

[0109] coefficients=polyfit(T,VCOM,2);

[0110] a=coefficients(1);

[0111] b = coefficients(2);

[0112] c = coefficients(3);

[0113] Substitute the fitted coefficients into the quadratic function model to obtain the compensation formula:

[0114] Vcom=0.00012T 2 -0.019T+0.44

[0115] Substitute the known data points into the fitting formula, calculate the fitting value, compare it with the experimental value, and check the fitting accuracy.

[0116] There is a linear relationship between the output register value of the temperature sensor and the actual temperature. The current register value REG1 can be converted to the actual temperature value by calibrating the data REG0 and T0. The calculation in the formula is based on the principle of linear interpolation, and the current actual temperature is calculated using the factory calibration value and the currently read register value.

[0117] During the temperature compensation application process, the microcontroller unit MCU works closely with the temperature sensor to ensure that the brightness of the display remains stable under different temperature conditions through a series of precise calculations and adjustment steps. The following are the specific steps in the temperature compensation process of the OLED microdisplay:

[0118] Step 1: During the working process of the display, the temperature sensor continuously monitors the ambient temperature and converts the collected temperature signal into a digital form, usually a register value REG. The register value has no unit, but is in a certain proportional relationship with the temperature. It can be converted into an actual temperature value through a predetermined conversion formula. The microcontroller unit MCU receives the register value sent by the temperature sensor through the IIC bus. After receiving the data, the microcontroller unit MCU will convert the register value into the actual ambient temperature value according to a preset temperature conversion formula, such as temperature value = register value * 0.561-57. In this way, the microcontroller unit MCU can accurately obtain the current ambient temperature and perform subsequent compensation calculations based on this. The built-in temperature sensor of the display is responsible for real-time monitoring of the temperature of the working environment of the display. The sensor transmits the temperature data to the microcontroller unit (microcontroller unit MCU) through the IIC bus. In this process, the temperature sensor converts the actual temperature into register values, such as REG0 and REG1, and then sends them to the microcontroller unit MCU through the IIC protocol;

[0119] Step 2: The microcontroller unit MCU will compare the currently acquired temperature value T1 with the standard operating temperature T0 of the display. If there is a difference between the two, the microcontroller unit MCU will calculate a temperature deviation value △T=T1-T0. This temperature deviation value represents the change of the current ambient temperature relative to the standard operating temperature. After calculating the temperature deviation, the microcontroller unit MCU will use the deviation value to decide how to adjust the operating parameters of the display, especially the Vcom value. The larger the temperature deviation, the greater the fluctuation of the brightness of the display. Therefore, the microcontroller unit MCU needs to adjust Vcom according to the deviation value to achieve brightness stability. Once the microcontroller unit MCU obtains the current temperature data, it will compare it with the preset target temperature T0 and calculate the temperature deviation △T between the current temperature and the target temperature. This temperature deviation is the basis of the compensation calculation and determines the adjustment range of the Vcom value.

[0120] Step 3: During the operation of the display, the microcontroller unit MCU will record historical temperature data. This data may include the temperature change record of the display since it was enabled, ensuring that the microcontroller unit MCU can obtain the trend of ambient temperature changes. The historical data is stored in the memory of the microcontroller unit MCU, usually a circular cache, for future predictions. Based on the recorded historical temperature data, the microcontroller unit MCU can analyze the trend of temperature changes. For example, the temperature may have shown an upward trend in the past period of time, or the change is relatively stable in certain periods of time. The microcontroller unit MCU uses this data to estimate the pattern of temperature changes, so as to better predict future temperature trends. By analyzing the historical temperature change trend, the microcontroller unit MCU can predict the temperature change in the future period of time, which allows the microcontroller unit to pre-adjust the Vcom value in advance to avoid unstable display brightness caused by temperature fluctuations. The temperature change is not just a simple difference between the current temperature and the target temperature. The ambient temperature usually shows a certain trend of change. In order to perform temperature compensation more accurately, the microcontroller unit MCU will analyze the historical temperature change trend and take it into account in the current compensation algorithm;

[0121] Step 4: The microcontroller unit MCU uses linear regression to predict the temperature change in the future. If the system detects that the temperature is gradually rising or falling, the microcontroller unit MCU will make Vcom adjustments in advance. This prediction can effectively avoid delayed response caused by temperature changes, making the brightness adjustment of the display smoother and more timely. According to the prediction of temperature change trends, the microcontroller unit MCU will adjust the Vcom value in advance. If the temperature is predicted to rise in the future, the microcontroller unit MCU will increase the Vcom value accordingly; if the temperature is expected to drop, the Vcom value will be reduced. The purpose of adjusting the Vcom value in advance is to ensure that the display brightness is stable before the actual temperature change occurs. By analyzing the historical temperature change trend, the microcontroller unit MCU can predict the temperature change in the future, which allows the microcontroller unit to pre-adjust the Vcom value in advance to avoid unstable display brightness caused by temperature fluctuations;

[0122] Step 5: The microcontroller unit MCU will calculate a compensation value through the temperature deviation △T and the historical temperature change trend. This compensation value determines the adjustment range of the Vcom value. Generally, the larger the temperature deviation, the larger the adjustment range of the Vcom value. The microcontroller unit MCU adjusts the Vcom value of the display in real time according to the calculated compensation value. If the temperature is high, the microcontroller unit MCU will reduce the Vcom value to avoid excessive display brightness; if the temperature is low, the Vcom value will be increased to maintain stable brightness. After each adjustment, the microcontroller unit MCU will send the new Vcom value to the display driver circuit through the IIC bus to ensure the stability of the display brightness. The Vcom value is a key parameter for controlling the brightness of the display. The microcontroller unit achieves brightness stability by accurately adjusting the Vcom value. The process of adjusting the Vcom value depends on the current temperature deviation and the trend prediction of historical temperature changes.

[0123] Step 6: After each Vcom value adjustment, the microcontroller unit MCU will monitor the brightness change of the display. If the brightness is stable, the compensation adjustment process is successful; if the brightness still fluctuates, the microcontroller unit MCU will continue to adjust the Vcom value until the display brightness is stable. With the accumulation of experience during use, the microcontroller unit MCU can continuously optimize the compensation algorithm based on feedback data. By analyzing the performance under different environmental conditions, the microcontroller unit MCU can further improve the accuracy and efficiency of temperature compensation. The compensation process is not just a one-way adjustment process. The microcontroller unit MCU will continue to monitor the display effect after compensation and make necessary adjustments based on the actual effect. Through the feedback mechanism, the microcontroller unit MCU can gradually optimize the compensation algorithm to ensure the long-term stability and accuracy of the compensation system. The temperature compensation process of the OLED microdisplay ensures the stability of the brightness of the display under different temperature conditions through a series of steps such as collecting and transmitting temperature data, calculating temperature deviation, analyzing historical change trends, predicting future temperature changes, adjusting the Vcom value in real time, and optimizing the compensation strategy. By comprehensively considering the current temperature, historical change trends and future predictions, the compensation algorithm can achieve accurate and timely brightness adjustment, thereby improving the consistency of the display effect and user experience.

[0124] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

Claims

1. A temperature sensor calibration method for an OLED microdisplay, characterized in that: include: A temperature compensation parameter storage module, wherein the temperature compensation parameter storage module is used to store temperature calibration data of the OLED microdisplay via a one-time programmable memory OTP; The steps for storing the temperature calibration data of the temperature compensation parameter storage module are as follows: Step 1: When the display is shipped from the factory, the temperature sensor is usually connected to the microcontroller unit MCU through the I2C protocol. The microcontroller unit MCU sends a read command to request to obtain the current temperature data from the temperature sensor. The temperature data sends the temperature information to the microcontroller unit MCU in the form of a digital signal, and writes these data into the one-time programmable memory OTP for storage; Step 2: The stored data includes the temperature value and the register value of the sensor. The temperature value is in °C, and the register value of the sensor has no unit, but is proportional to the temperature value. The formula is as follows: temperature value = register value * 0.561-57; Step 3: After the calibration data is stored, each time the display is started, the microcontroller unit MCU reads the temperature calibration data and register value REG0 in the one-time programmable memory OTP through the IIC bus; Step 4: Read the current temperature register value REG1 and use the following formula to get the calibrated temperature value: T1=(REG1+OFFSET)×0.561-57 0.561 and 57 in the above formula are the parameters in the previous temperature calculation formula. Set T0' to the expected temperature value calculated by REG0 and the relevant calibration formula. Set T1' to the expected temperature value calculated by REG1 and the calibration formula under this value. Set T0 to the standard operating temperature, and compare T0' with the standard operating temperature T0 to calculate the offset OFFSET. By adding OFFSET to T1', the actual operating temperature T1 of the display can be obtained.

2. The temperature sensor calibration method of an OLED microdisplay according to claim 1, characterized in that: The temperature calibration data storage structure of the temperature compensation parameter storage module includes: Gamma storage location: MicroOLED uses 9 / 10-bit gamma data storage to save gamma data, and stores gamma calibration data separately according to grayscale values ​​and different colors of red, green, and blue; Data storage format: The red, green, and blue gamma data corresponding to the grayscale value are stored in different byte positions, respectively. The specific storage format is shown in Figure 3.

3. The temperature sensor calibration method of an OLED microdisplay according to claim 1, characterized in that: The one-time programmable memory OTP is a non-volatile memory, and its data cannot be changed once written.

4. The temperature sensor calibration method of an OLED microdisplay according to claim 1, characterized in that: The specific operation process of the one-time programmable memory OTP is as follows: Writing temperature calibration data at the factory: During the device manufacturing stage, the calibration data of the temperature sensor is written into the one-time programmable memory OTP; Reading data at each startup: Each time the OLED display is started, the microcontroller unit MCU reads the temperature calibration data in the one-time programmable memory OTP through the IIC bus. After reading the data, the microcontroller unit MCU calculates the compensation value based on the current temperature value and the stored calibration data; Temperature compensation calculation and application: The microcontroller unit MCU adjusts the operating parameters of the display in real time according to the compensation formula to ensure stable brightness.

5. The temperature sensor calibration method of an OLED microdisplay according to claim 1, characterized in that: The one-time programmable memory OTP is a non-volatile memory, which ensures that data is not lost in the event of a power outage, so the microcontroller unit MCU can read accurate calibration data each time it is started.

6. An external temperature compensation method for an OLED microdisplay, characterized in that: The external temperature compensation method includes: determining a temperature compensation formula and applying temperature compensation; The steps to determine the temperature compensation formula include: Step 1: Place the microdisplay on the test platform and connect the probe and communication line; Step 2: Set the temperature to -40 degrees Celsius. After it stabilizes, send a command through the computer to adjust VCOM so that the brightness level remains at the preset value, and record the VCOM and temperature values ​​at this time; Step 3: Repeat step 2 and gradually adjust the temperature in the test box to -35℃, -30℃, 60℃, and 65℃. After each temperature adjustment, wait for the system to reach a stable state. At each temperature point, repeat step 2 to adjust Vcom to keep the brightness of the display stable at the target value, and record the current Vcom value and temperature value. Step 4: Use the fitting tool to perform quadratic function fitting on VCOM and the corresponding temperature value. Use the quadratic function fitting algorithm to find the optimal fitting curve. After the fitting is completed, a formula is obtained. For our existing products, the formula after fitting is as follows: Vcom=0.00012T 2 -0.019T+0.44 T is the test temperature, and Vcom is the Vcom value required to keep the brightness stable at this temperature. So far, the temperature compensation formula has been determined; The steps to apply temperature compensation include: Step 1: Calculate the current actual temperature value through the formula. To ensure stability, window translation filtering can be performed. The formula is as follows: T1=(REG1+OFFSET)×0.561-57 in Among them, REG1 is the temperature register value, T0 and REG0 are the temperature value and register value in the one-time programmable memory OTP; Step 2: Calculate the Vcom value that should be output according to the current actual temperature value T1, that is, calculate according to the formula determined in "Determination of temperature compensation formula"; Step 3: The calculated Vcom value is transmitted to the display driving circuit through the IIC bus, and the Vcom value of the display is updated in real time. The driving chip receives the command and adjusts the common voltage Vcom of the display to the new set value. The driving circuit adjusts the working state of the display according to the Vcom value. Repeat the above steps at regular intervals to achieve the temperature compensation function.

7. The external temperature compensation method of an OLED microdisplay according to claim 6, characterized in that: The Vcom value directly affects the brightness of the display. By adjusting the Vcom value, the electric field strength of the display can be adjusted, thereby controlling the luminous brightness.

8. The external temperature compensation method of an OLED microdisplay according to claim 6, characterized in that: The operation of using the fitting tool to perform quadratic function fitting on VCOM and the corresponding temperature value is as follows: Enter temperature (T) as the independent variable and VCOM as the dependent variable into the fitting tool, and select the quadratic function model, that is: VCOM = aT 2 +bT+c, run the fitting algorithm in the tool to calculate the coefficients a, b, and c of the best fitting curve. Take the MATLAB mathematical calculation tool as an example: Assuming the data is stored in variables T and VCOM, then: coefficients=polyfit(T,VCOM,2); a=coefficients(1); b = coefficients(2); c = coefficients(3); Substitute the fitted coefficients into the quadratic function model to obtain the compensation formula: Vcom=0.00012T 2 -0.019T+0.44 Substitute the known data points into the fitting formula, calculate the fitting values, compare them with the experimental values, and check the fitting accuracy.

9. The external temperature compensation method of an OLED microdisplay according to claim 6, characterized in that: There is a linear relationship between the output register value of the temperature sensor and the actual temperature. The current register value REG1 can be converted into the actual temperature value through the calibration data REG0 and T0.

10. The external temperature compensation method of an OLED micro display according to claim 9, characterized in that: In the temperature compensation application process, the microcontroller unit MCU works closely with the temperature sensor to ensure that the brightness of the display remains stable under different temperature conditions through a series of precise calculations and adjustment steps. The following are the specific steps in the temperature compensation process of the OLED microdisplay: Step 1: During the working process of the display, the temperature sensor continuously monitors the ambient temperature and converts the collected temperature signal into a digital form, usually a register value REG. The register value has no unit, but is in a certain proportional relationship with the temperature. It can be converted into an actual temperature value through a predetermined conversion formula. The microcontroller unit MCU receives the register value sent by the temperature sensor through the IIC bus. After receiving the data, the microcontroller unit MCU will convert the register value into the actual ambient temperature value according to a preset temperature conversion formula, such as temperature value = register value * 0.561-57. In this way, the microcontroller unit MCU can accurately obtain the current ambient temperature and perform subsequent compensation calculations based on this; Step 2: The microcontroller unit MCU will compare the currently acquired temperature value T1 with the standard operating temperature T0 of the display. If there is a difference between the two, the microcontroller unit MCU will calculate a temperature deviation value △T = T1-T0. This temperature deviation value represents the change of the current ambient temperature relative to the standard operating temperature. After calculating the temperature deviation, the microcontroller unit MCU will use the deviation value to decide how to adjust the operating parameters of the display; Step 3: During the operation of the display, the microcontroller unit MCU will record historical temperature data. This data may include the temperature change record of the display since it was enabled, ensuring that the microcontroller unit MCU can obtain the change trend of the ambient temperature. The historical data is stored in the memory of the microcontroller unit MCU, usually a circular cache, for future predictions. Based on the recorded historical temperature data, the microcontroller unit MCU can analyze the temperature change trend. For example, the temperature may show an upward trend in the past period of time, or the change is relatively stable in certain periods of time. The microcontroller unit MCU uses this data to estimate the temperature change pattern, so as to better predict the future temperature trend. By analyzing the historical temperature change trend, the microcontroller unit MCU can predict the temperature change in the future period of time, which enables the microcontroller unit to pre-adjust the Vcom value in advance to avoid the instability of the display brightness caused by temperature fluctuations; Step 4: The microcontroller unit MCU uses linear regression to predict the temperature change in the future. If the system detects that the temperature is gradually rising or falling, the microcontroller unit MCU will make Vcom adjustments in advance. This prediction can effectively avoid delayed response caused by temperature changes, making the brightness adjustment of the display smoother and more timely. According to the prediction of the temperature change trend, the microcontroller unit MCU will adjust the Vcom value in advance. If the temperature is predicted to rise in the future, the microcontroller unit MCU will increase the Vcom value accordingly; if the temperature is expected to drop, the Vcom value will be reduced. The purpose of adjusting the Vcom value in advance is to ensure that the display brightness is stable before the actual temperature change occurs. Step 5: The microcontroller unit MCU will calculate a compensation value based on the temperature deviation △T and the historical temperature change trend. This compensation value determines the adjustment range of the Vcom value. Generally, the larger the temperature deviation, the larger the adjustment range of the Vcom value. The microcontroller unit MCU adjusts the Vcom value of the display in real time according to the calculated compensation value. If the temperature is high, the microcontroller unit MCU will reduce the Vcom value to avoid excessive display brightness; if the temperature is low, the Vcom value will be increased to maintain a stable brightness. After each adjustment, the microcontroller unit MCU will send the new Vcom value to the display driver circuit through the IIC bus to ensure the stability of the display brightness; Step 6: After each Vcom value adjustment, the microcontroller unit MCU will monitor the brightness changes of the display. If the brightness is stable, the compensation adjustment process is successful; if the brightness still fluctuates, the microcontroller unit MCU will continue to adjust the Vcom value until the display brightness is stable. With the accumulation of experience during use, the microcontroller unit MCU can continuously optimize the compensation algorithm based on feedback data. By analyzing the performance under different environmental conditions, the microcontroller unit MCU can further improve the accuracy and efficiency of temperature compensation.

Images