Temperature sensor calibration and external temperature compensation method for OLED microdisplay

Abstract

The application 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, which comprises a temperature compensation parameter storage module, wherein the temperature compensation parameter storage module is used for saving temperature calibration data of the OLED micro-display through one-time programmable memory (OTP). The temperature sensor calibration and external temperature compensation method for the OLED micro-display is used for calculating an actual working temperature Tactual by using a current temperature register value REG1 measured by a temperature sensor, factory calibration data T0 and REG0, compensating the change of brightness by adjusting a common voltage Vcom in real time, accurately controlling the luminous brightness of the display by adjusting the electric field intensity in combination with a temperature compensation formula, increasing the Vcom in a low-temperature environment to compensate the brightness drop, reducing the Vcom in a high-temperature environment to prevent excessive light emission or thermal damage, and solving the problem of inconsistent display effect in long-term use, thereby improving the user experience.

Description

Technical Field

[0001] This invention relates to the field of OLED microdisplay technology, specifically to a method for calibrating a temperature sensor and compensating for an external temperature in an OLED microdisplay. Background Technology

[0002] OLED microdisplays are small displays based on organic light-emitting diode (OLED) technology. Unlike traditional LCD displays, OLED displays do not require a backlight. Their self-emissive nature results in more vibrant colors, higher contrast, and faster response times. OLED microdisplays offer small size and high resolution, making them widely used in various small display devices, such as smart glasses, virtual reality headsets, augmented reality devices, micro-projectors, and wearable devices.

[0003] The performance of OLED (Organic Light Emitting Diode) displays is closely related to temperature changes, especially in terms of brightness, color accuracy, and long-term display stability. Temperature variations directly affect the performance of OLED displays, causing significant deviations. This phenomenon stems primarily from the working principle of OLED displays and the characteristics of the organic materials they use. 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 the OLED materials decreases, leading to reduced brightness. Conversely, when the temperature decreases, the luminous efficiency of the OLED materials may increase, resulting in excessive brightness. Therefore, temperature fluctuations directly affect the brightness stability of the display, making it impossible to maintain consistent display performance. To ensure that OLED displays provide stable display performance under different temperature environments, effective temperature compensation is necessary. However, in practical applications, OLED displays operate in dynamic environments with significant temperature variations, especially in wearable devices and automotive displays, where ambient temperatures may fluctuate frequently. Therefore, traditional temperature compensation methods are based on static calibration data, which fails to dynamically respond to temperature changes or adjust the display performance in real time. Static compensation schemes are effective in the short term, but they will fail in the long term due to continuous changes in temperature and environment, resulting in inconsistent display effects. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a method for calibrating a temperature sensor and externally compensating for OLED microdisplays. This method solves the problem that the performance of OLED displays is affected by temperature changes, and that traditional static temperature compensation methods cannot dynamically respond to ambient temperature fluctuations, leading to inconsistent display effects over long-term use.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for calibrating a temperature sensor for an OLED microdisplay includes:

[0009] A temperature compensation parameter storage module is used to save the temperature calibration data of the OLED microdisplay via a one-time programmable memory (OTP).

[0010] The temperature calibration data storage steps for the temperature compensation parameter storage module are as follows:

[0011] Step 1: When the display leaves the factory, the temperature sensor is connected to the microcontroller unit (MCU) via the I2C protocol. The MCU sends a read command to request the current temperature data from the temperature sensor. The temperature data is sent to the MCU in the form of a digital signal and is written into the one-time programmable memory (OTP) for storage.

[0012] Step 2: The stored data includes temperature values ​​and sensor register values. The temperature values ​​are in °C, while the sensor register values ​​are unitless but have a certain proportional relationship with the temperature values. The formula is as follows: Temperature value = Register value * 0.561 - 57.

[0013] Step 3: After the calibration data is stored, each time the display is turned on, the microcontroller unit (MCU) reads the temperature calibration data and register value REG0 from the one-time programmable memory (OTP) via the I2C bus.

[0014] Step 4: Read the current temperature register value REG1 and use the following formula to obtain the calibrated temperature value:

[0015] T1 = REG1 + OFFSET × 0.561 − 57

[0016] OFFSET = T0 + 570.561 − REG0

[0017] In the above formula, 0.561 and 57 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. Add the OFFSET to T1' to obtain the actual operating temperature T1 of the display.

[0018] Preferably, the temperature calibration data storage structure of the temperature compensation parameter storage module includes: Gamma storage location: MicroOLED uses a 9 / 10-bit Gamma data storage method to store Gamma data, and stores Gamma calibration data according to grayscale values ​​and different colors of red, green, and blue respectively; Data storage format: The Gamma data corresponding to the grayscale values ​​of red, green, and blue are stored in different byte positions respectively.

[0019] Preferably, the one-time programmable memory (OTP) is a non-volatile memory.

[0020] Preferably, the specific operation process of the one-time programmable memory (OTP) is as follows: 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); Data is read upon each startup: Each time the OLED display is started, the microcontroller unit (MCU) reads the temperature calibration data from the OTP via the I2C bus. After reading the data, the MCU calculates the compensation value based on the current temperature value and the stored calibration data; Temperature compensation calculation and application: The MCU adjusts the display's operating parameters in real time according to the compensation formula to ensure stable brightness.

[0021] An external temperature compensation method for an OLED microdisplay, the external temperature compensation method comprising: determining a temperature compensation formula and applying temperature compensation;

[0022] The steps for determining the temperature compensation formula include:

[0023] Step 1: Place the microdisplay in the test platform and connect the probe and communication cable;

[0024] Step 2: Set the temperature to -40 degrees Celsius. After stabilizing, send a command via computer to adjust Vcom to maintain the brightness level at the preset value, and record the Vcom and temperature values ​​at this time.

[0025] Step 3: Repeat Step 2, gradually adjusting the temperature inside the test chamber 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.

[0026] Step 4: Use a 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 fitting, a formula is obtained, which is as follows:

[0027] Vcom = 0.00012T² − 0.019T + 0.44

[0028] T is the test temperature, and Vcom is the common voltage value required to maintain stable brightness at this temperature. Thus, the temperature compensation formula has been determined.

[0029] The steps for applying temperature compensation include:

[0030] Step 1: Calculate the current actual temperature value using the formula. To ensure stability, a window shift filter is applied. The formula is as follows:

[0031] T1 = REG1 + OFFSET × 0.561 − 57

[0032] Where OFFSET = T0 + 570.561 − REG0

[0033] REG1 is the temperature register value, and T0 and REG0 are the temperature value and register value in the one-time programmable memory (OTP).

[0034] Step 2: Calculate the Vcom value that should be output based on the current actual temperature value T1, that is, calculate it according to the formula determined in "Temperature Compensation Formula Determination";

[0035] Step 3: The calculated Vcom value is transmitted to the display driver circuit via the I2C 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.

[0036] Repeating the above steps periodically will enable the temperature compensation function.

[0037] Preferably, the Vcom value directly affects the brightness of the display. By adjusting the Vcom value, the electric field strength of the display is adjusted, thereby controlling the luminous brightness.

[0038] Preferably, the operation of using a fitting tool to perform quadratic function fitting on Vcom and the corresponding temperature value is as follows:

[0039] Using temperature T as the independent variable and Vcom as the dependent variable, the fitting tool is selected, and a quadratic function model is chosen: Vcom = aT² + bT + c. The process of calculating the best-fit curve in MATLAB is as follows:

[0040] Assuming the data is stored in variables T and Vcom, then:

[0041] coefficients=polyfit(T,Vcom,2);

[0042] a = coefficients(1);

[0043] b = coefficients(2);

[0044] c = coefficients(3);

[0045] Substituting the fitted coefficients into the quadratic function model, we obtain the compensation formula:

[0046] Vcom = 0.00012T² − 0.019T + 0.44

[0047] Substitute the known data points into the fitting formula, calculate the fitted value, compare it with the experimental value, and check the fitting accuracy.

[0048] Preferably, the register value REG1 has a linear relationship with the actual temperature, and the calibration data REG0 and T0 convert the current register value REG1 into the actual temperature value.

[0049] Preferred specific steps in the temperature compensation process of OLED microdisplays:

[0050] Step 1: During the operation of the display, the temperature sensor continuously monitors the ambient temperature and converts the collected temperature signal into a digital form, which is a register value REG. This register value has no unit, but it is proportional to the temperature. It is converted into the actual temperature value through a predetermined conversion formula. The microcontroller unit (MCU) receives the register value sent by the temperature sensor through the I2C bus. After receiving the data, the MCU will convert the register value into the actual ambient temperature value according to the preset temperature conversion formula: Temperature value = Register value * 0.561 - 57.

[0051] 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 MCU will calculate a temperature deviation value ΔT = 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 MCU will use the deviation value to determine how to adjust the operating parameters of the display.

[0052] Step 3: During the operation of the display, the microcontroller unit (MCU) records historical temperature data, including temperature change records since the display was turned on. This ensures that the MCU can obtain the trend of ambient temperature changes. The historical data is stored in the memory of the MCU as a circular cache for future prediction. Based on the recorded historical temperature data, the MCU analyzes the temperature change trend.

[0053] Step 4: The microcontroller unit (MCU) uses linear regression to predict temperature changes over a future period. If the system detects that the temperature is gradually rising or falling, the MCU will adjust Vcom in advance. This prediction effectively avoids delayed response caused by temperature changes, making the brightness adjustment of the display smoother and more timely. Based on the predicted temperature change trend, the MCU will adjust the Vcom value in advance.

[0054] Step 5: Based on the temperature deviation ΔT and historical temperature change trends, the microcontroller unit (MCU) calculates a compensation value. This compensation value determines the adjustment range of the Vcom value. The larger the temperature deviation, the larger the adjustment range of the Vcom value will be. The MCU adjusts the Vcom value on the display in real time according to the calculated compensation value.

[0055] Step 6: After each Vcom value adjustment, the microcontroller unit (MCU) will monitor the brightness change of the display.

[0056] (III) Beneficial Effects

[0057] Compared with the prior art, the present invention provides a method for calibrating the temperature sensor and externally compensating for the temperature of an OLED microdisplay, which has the following advantages:

[0058] 1. The temperature sensor calibration and external temperature compensation method for this OLED microdisplay 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. It compensates for brightness changes by adjusting the common voltage Vcom in real time. Combined with the temperature compensation formula, it precisely controls the display's brightness by adjusting the electric field strength. In low-temperature environments, Vcom is increased to compensate for the decrease in brightness, and in high-temperature environments, Vcom is decreased to prevent excessive light emission or thermal damage. This solves the problem of inconsistent display effects during long-term use and improves the user experience.

[0059] 2. The temperature sensor calibration and external temperature compensation method for this OLED microdisplay establishes a correspondence between register values ​​and actual temperatures through linear interpolation-based temperature calibration. A temperature compensation formula generated using a quadratic function fitting algorithm provides the display with broad temperature adaptability. Even within a wide temperature range of -40℃ to 65℃, 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 various complex environments, such as extremely cold regions, tropical high-temperature environments, or industrial equipment, significantly enhancing its environmental adaptability and expanding its application scenarios.

[0060] 3. The temperature sensor calibration and external temperature compensation method for this OLED microdisplay monitors the display's operating temperature in real time and dynamically adjusts the Vcom value to prevent performance degradation or component damage caused by overheating or underheating. Furthermore, the use of OTP memory ensures the long-term stability of calibration data, allowing the MCU to accurately read and apply this data each time it starts up. This dual protection mechanism significantly reduces the device's failure rate, extends the display's lifespan, and improves overall reliability.

[0061] 4. The temperature sensor calibration and external temperature compensation method for this OLED microdisplay utilizes a temperature sensor to monitor the operating temperature in real time and adjusts the Vcom value according to a 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, avoiding color drift or display distortion caused by temperature changes, and providing users with a superior visual experience.

[0062] 5. The temperature sensor calibration and external temperature compensation method for this OLED microdisplay, by monitoring the temperature in real time and accurately calculating the temperature deviation, allows the microcontroller unit (MCU) to precisely adjust the display's Vcom value under different temperature conditions, thereby ensuring stable display brightness. This precise temperature compensation effectively eliminates display brightness fluctuations caused by temperature changes, improving the stability and consistency of the display effect.

[0063] 6. The temperature sensor calibration and external temperature compensation method for this OLED microdisplay analyzes historical temperature data, allowing the microcontroller unit (MCU) to predict future temperature trends (e.g., gradual increase or decrease) and adjust the Vcom value in advance. This predictive mechanism effectively avoids delayed response caused by temperature fluctuations, enabling the display to adjust its brightness before temperature changes occur, ensuring smoother and more timely brightness adjustments, and reducing the impact of temperature changes on display quality.

[0064] 7. The temperature sensor calibration and external temperature compensation method for this OLED microdisplay enables more precise brightness control through real-time, intelligent temperature compensation. This means the display can avoid unnecessary high-power operation. For example, in low-temperature environments, the MCU can moderately increase the Vcom value to maintain brightness, while in high-temperature environments, it can decrease the Vcom value to prevent excessive power consumption. This efficient energy management extends the display's lifespan, reduces energy consumption, and improves overall system efficiency. Attached Figure Description

[0065] Figure 1 This is a schematic diagram of a temperature sensor calibration method for an OLED microdisplay proposed in this invention;

[0066] Figure 2 This is a schematic diagram of an external temperature compensation method for an OLED microdisplay proposed in this invention;

[0067] Figure 3 This is a schematic diagram of the data storage format for a temperature sensor calibration and external temperature compensation method for an OLED microdisplay proposed in this invention. Detailed Implementation

[0068] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0069] Please see Figure 1 - Figure 3 A method for calibrating a temperature sensor for an OLED microdisplay, comprising:

[0070] Temperature compensation parameter storage module: The temperature compensation parameter storage module is used to save the temperature calibration data of the OLED microdisplay through a one-time programmable memory (OTP). The stored calibration data mainly includes the correspondence between temperature values ​​and corresponding sensor readings.

[0071] The temperature calibration data storage steps for the temperature compensation parameter storage module are as follows:

[0072] Step 1: When the display leaves the factory, the temperature sensor is connected to the microcontroller unit (MCU) via the I2C protocol. The MCU sends a read command to request the current temperature data from the temperature sensor. The temperature data is sent to the MCU in the form of a digital signal and is written into the one-time programmable memory (OTP) for storage.

[0073] Step 2: The stored data includes temperature values ​​and sensor register values. The temperature values ​​are in °C, while the sensor register values ​​are unitless but have a certain proportional relationship with the temperature values. The formula is as follows: Temperature value = Register value * 0.561 - 57.

[0074] Step 3: After the calibration data is stored, each time the display is turned on, the microcontroller unit (MCU) reads the temperature calibration data and register value REG0 from the one-time programmable memory (OTP) via the I2C bus.

[0075] Step 4: Read the current temperature register value REG1 and use the following formula to obtain the calibrated temperature value:

[0076]

[0077]

[0078] In the above formula, 0.561 and 57 are the parameters in the previous temperature calculation formula. T0' is set to the expected temperature value calculated by REG0 and the relevant calibration formula. T1' is set to the expected temperature value calculated by REG1 and the calibration formula under this value. T0 is set to the standard operating temperature, T0 is 25℃. T0' is compared with T0 to calculate the offset. By adding the offset to T1', the actual operating temperature T1 of the monitor can be obtained. The offset is calculated to find the difference between the actual temperature and the expected temperature of the monitor. Due to the possibility of errors in the temperature sensor measurement or the influence of other factors, there may be a deviation between the temperature value at calibration, that is, the temperature T0 recorded at the factory, and the temperature value T0' calculated based on the formula. The current actual temperature value T1 is then calculated using the offset and T1'. The actual temperature T1 can be calculated using the known offset and T1'. Assuming T1' is the expected temperature value calculated from the current sensor value 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. 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.

[0079] The temperature calibration data storage structure of the temperature compensation parameter storage module includes:

[0080] Gamma storage location: MicroOLED uses a 9 / 10-bit Gamma data storage method to store Gamma data, storing Gamma calibration data separately according to grayscale value and different colors (red, green, blue);

[0081] Data storage format: The Gamma data corresponding to the grayscale values ​​(red, green, and blue) are stored in different byte locations. The specific storage format is as follows: Figure 3By storing temperature sensor calibration data in this structure, 3 bytes of space can be saved for storing temperature data. In the Gamma data structure of an OLED display, the smallest storage unit is 1 byte. Temperature calibration data (i.e., temperature values ​​and sensor register values) would normally require separate space. By embedding this temperature data into the Gamma data structure and utilizing some free bytes under grayscale values ​​(such as placeholders represented by "XX" values), the 3 extra bytes that would otherwise be needed can be saved. This is because not every position in the Gamma data structure is completely filled; temperature data can be cleverly embedded within it. Specifically, if the Gamma data has redundant bits or bytes under certain grayscale values... (For example, the lower 8 bits are empty). These empty bits can be used by temperature calibration data, thus avoiding the need to allocate additional storage space for temperature data separately. For example, some bytes in the gamma data with a grayscale value of 0 are free (e.g., "8 bits available"). In this case, the temperature calibration data can be stored directly in these free bytes, so that there is no need to allocate an additional 3 bytes for storing temperature data, saving storage space. Embedding the temperature sensor calibration data into the storage structure of the gamma data and using the existing storage space to store the temperature data, instead of allocating space separately for it, can save 3 bytes of storage space. This storage optimization method helps to achieve efficient storage of temperature data and display calibration data with limited storage resources.

[0082] One-time programmable memory (OTP) is a type of non-volatile memory whose data, once written, cannot be changed. It is suitable for storing temperature calibration data, ensuring the uniqueness and stability of temperature compensation data for each display. The working principle of OTP is similar to that of ordinary memory, but its key characteristic is "one-time write." Once data is written to the OTP, it will remain unchanged forever until the device is disassembled or damaged. Due to its unmodifiable nature, OTP is ideal for storing data that needs to remain stable over a long period, such as temperature sensor calibration data. In this invention, OTP is used to store the display's temperature calibration data.

[0083] The specific operation procedure of the One-Time Programmable Memory (OTP) is as follows:

[0084] 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). This data includes the mapping relationship between the specific temperature of each display and the sensor reading.

[0085] Read data upon startup: Each time the OLED display is powered on, the microcontroller unit (MCU) reads the temperature calibration data from the one-time programmable memory (OTP) via the I2C bus. After reading the data, the MCU calculates the compensation value based on the current temperature value and the stored calibration data.

[0086] Temperature compensation calculation and application: The microcontroller unit (MCU) adjusts the display's operating parameters in real time according to the compensation formula to ensure stable brightness. This process is achieved through communication between the MCU and the display driver via the I2C bus.

[0087] One-time programmable memory (OTP) is a non-volatile memory that ensures data is not lost when power is off. Therefore, the microcontroller unit (MCU) can read accurate calibration data every time it is started.

[0088] An external temperature compensation method for an OLED microdisplay includes: determining the temperature compensation formula and applying the temperature compensation.

[0089] The steps for determining the temperature compensation formula include:

[0090] Step 1: Place the microdisplay in the test platform and connect the probe and communication cable;

[0091] Step 2: Set the temperature to -40 degrees Celsius. After stabilizing, send a command via computer to adjust Vcom to maintain the brightness level at the preset value, and record the Vcom and temperature values ​​at this time.

[0092] Step 3: Repeat Step 2, gradually adjusting the temperature inside the test chamber 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 value at different temperatures, a Vcom and temperature data table covering the working temperature range can be formed, providing sufficient data support for subsequent fitting formulas.

[0093] Step 4: Use a fitting tool to perform quadratic function fitting on Vcom and the corresponding temperature value. Using a quadratic function fitting algorithm, find the optimal fitting curve. After fitting, a formula is obtained. For our company's existing products, the formula after fitting is as follows:

[0094]

[0095] T is the test temperature, and Vcom is the Vcom value required to maintain stable brightness at this temperature. The temperature compensation formula is now determined.

[0096] The steps for applying temperature compensation include:

[0097] Step 1: Calculate the current actual temperature value using the formula. To ensure stability, a window shift filter can be applied. The formula is as follows:

[0098]

[0099] in

[0100] REG1 is the temperature register value, and T0 and REG0 are the temperature value and register value in the one-time programmable memory (OTP).

[0101] Step 2: Calculate the Vcom value that should be output based on the temperature, that is, calculate it according to the formula determined in "Temperature Compensation Formula Determination";

[0102] Step 3: The calculated Vcom value is transmitted to the display driver circuit via the I2C 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 stable display effect.

[0103] Repeating the above steps periodically enables temperature compensation. Since ambient temperature can change frequently, temperature compensation is not a one-time operation but a continuous process. This process ensures the display responds to temperature changes in real time and dynamically adjusts brightness, ensuring the OLED display provides stable display performance under different temperature conditions. The Vcom value directly affects the display's brightness. By adjusting the Vcom value, the display's electric field strength can be adjusted, thereby controlling the luminous brightness. In low-temperature environments, the luminous efficiency of OLED materials decreases, requiring an increase in Vcom to compensate for the brightness reduction. Therefore, recording the Vcom value at this time helps establish the correlation between brightness and temperature.

[0104] The following steps demonstrate how to use a fitting tool to perform a quadratic function fit between Vcom and the corresponding temperature value:

[0105] Using temperature T as the independent variable and Vcom as the dependent variable, the fitting tool was selected, and a quadratic function model was chosen: Vcom = aT 2 +bT+c, in the tool, runs the fitting algorithm and calculates the coefficients a, b, and c of the best-fit curve. Taking MATLAB's mathematical calculation tools as an example:

[0106] Assuming the data is stored in variables T and Vcom, then:

[0107] coefficients=polyfit(T,Vcom,2);

[0108] a = coefficients(1);

[0109] b = coefficients(2);

[0110] c = coefficients(3);

[0111] Substituting the fitted coefficients into the quadratic function model, we obtain the compensation formula:

[0112]

[0113] Substitute the known data points into the fitting formula, calculate the fitted value, compare it with the experimental value, and check the fitting accuracy.

[0114] The output register value of the temperature sensor has a linear relationship with the actual temperature. By using calibration data REG0 and T0, the current register value REG1 can be converted into the actual temperature value. The calculation in the formula is based on the principle of linear interpolation, using the factory calibration value and the currently read register value to calculate the current actual temperature.

[0115] In temperature compensation applications, the microcontroller unit (MCU) works closely with the temperature sensor, employing a series of precise calculations and adjustments to ensure that the display's brightness remains stable under varying temperature conditions. The following are the specific steps involved in the temperature compensation process for OLED microdisplays:

[0116] Step 1: During the operation of the display, the temperature sensor continuously monitors the ambient temperature and converts the collected temperature signal into a digital form, a register value REG. This register value has no unit but is proportional to the temperature. It can be converted into an actual temperature value using a predetermined conversion formula. The microcontroller unit (MCU) receives the register value sent by the temperature sensor via the I2C bus. After receiving the data, the MCU converts the register value into the actual ambient temperature value according to the preset temperature conversion formula, such as temperature value = register value * 0.561 - 57. In this way, the MCU can accurately obtain the current ambient temperature and perform subsequent compensation calculations based on it. The temperature sensor built into the display is responsible for monitoring the temperature of the display's operating environment in real time. This sensor transmits the temperature data to the microcontroller unit (MCU) via the I2C bus. During this process, the temperature sensor converts the actual temperature into a register value, such as REG0 or REG1, and then sends it to the MCU via the I2C protocol.

[0117] Step 2: The microcontroller unit (MCU) compares the currently acquired temperature value T1 with the standard operating temperature T0 of the display. If there is a difference between the two, the MCU calculates a temperature deviation value ΔT = T1 - T0. This temperature deviation value represents the change in the current ambient temperature relative to the standard operating temperature. After calculating the temperature deviation, the MCU uses the deviation value to determine how to adjust the operating parameters of the display, especially the Vcom value. The larger the temperature deviation, the greater the fluctuation in the brightness of the display may be. Therefore, the MCU needs to adjust Vcom according to the deviation value to achieve brightness stability. Once the MCU obtains the current temperature data, it compares it with the preset target temperature T0 and calculates the temperature deviation ΔT between the current temperature and the target temperature. This temperature deviation is the basis for compensation calculation and determines the adjustment range of the Vcom value.

[0118] Step 3: During the operation of the display, the microcontroller unit (MCU) records historical temperature data. This data can include temperature change records since the display was turned on, ensuring that the MCU can obtain the trend of ambient temperature changes. The historical data is stored in the MCU's memory as a circular cache for future prediction. Based on the recorded historical temperature data, the MCU can analyze temperature change trends. For example, the temperature may have shown an upward trend over a period of time, or it may have changed relatively steadily over certain periods. The MCU uses this data to estimate the temperature change pattern, thereby better predicting future temperature trends. By analyzing historical temperature change trends, the MCU can predict temperature changes over a period of time in the future. This allows the MCU to pre-adjust the Vcom value in advance, avoiding instability in display brightness caused by temperature fluctuations. Temperature changes are not just a simple difference between the current temperature and the target temperature; ambient temperature will show certain trends. In order to perform temperature compensation more accurately, the MCU analyzes the historical temperature change trends and incorporates them into the current compensation algorithm.

[0119] Step 4: The microcontroller unit (MCU) uses linear regression to predict temperature changes over a future period. If the system detects that the temperature is gradually rising or falling, the MCU will adjust Vcom in advance. This prediction effectively avoids delayed response caused by temperature changes, making the display brightness adjustment smoother and more timely. Based on the predicted temperature change trend, the MCU will adjust the Vcom value in advance. If the predicted temperature will rise, the MCU will increase the Vcom value accordingly; if the temperature is expected to fall, the Vcom value will decrease. 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 historical temperature change trends, the MCU can predict temperature changes over a future period, allowing the MCU to pre-adjust the Vcom value and avoid instability in display brightness caused by temperature fluctuations.

[0120] Step 5: Based on the temperature deviation ΔT and historical temperature change trends, the microcontroller unit (MCU) calculates a compensation value. This compensation value determines the adjustment range of the Vcom value. The larger the temperature deviation, the larger the adjustment range of the Vcom value will be. The MCU adjusts the Vcom value of the display in real time according to the calculated compensation value. If the temperature is high, the MCU will reduce the Vcom value to avoid excessive display brightness; if the temperature is low, it will increase the Vcom value to maintain stable brightness. After each adjustment, the MCU sends the new Vcom value to the display driver circuit via the I2C bus to ensure the stability of the display brightness. The Vcom value is a key parameter for controlling the display brightness. The microcontroller unit achieves brightness stability by precisely adjusting the Vcom value. The process of adjusting the Vcom value depends on the current temperature deviation and the prediction of historical temperature change trends.

[0121] Step Six: After each Vcom value adjustment, the microcontroller unit (MCU) monitors the brightness changes of the display. If the brightness is stable, the compensation adjustment process is successful. If the brightness continues to fluctuate, the MCU will continue to adjust the Vcom value until the display brightness stabilizes. With accumulated experience during use, the MCU can continuously optimize the compensation algorithm based on feedback data. By analyzing the performance under different environmental conditions, the MCU can further improve the accuracy and efficiency of temperature compensation. The compensation process is not just a one-way adjustment process; the MCU continuously monitors the display effect after compensation and makes necessary adjustments based on the actual effect. Through the feedback mechanism, the 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 involves a series of steps, including collecting and transmitting temperature data, calculating temperature deviation, analyzing historical trends, predicting future temperature changes, adjusting the Vcom value in real time, and optimizing the compensation strategy. This ensures the stability of the display's brightness under different temperature conditions. By comprehensively considering the current temperature, historical trends, and future predictions, the compensation algorithm can achieve precise and timely brightness adjustment, thereby improving the consistency of the display effect and the user experience.

[0122] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A method for calibrating a temperature sensor for an OLED microdisplay, characterized in that: include: A temperature compensation parameter storage module is used to save the temperature calibration data of the OLED microdisplay via a one-time programmable memory (OTP). The temperature calibration data storage steps for the temperature compensation parameter storage module are as follows: Step 1: When the display leaves the factory, the temperature sensor is connected to the microcontroller unit (MCU) via the I2C protocol. The MCU sends a read command to request the current temperature data from the temperature sensor. The temperature data is sent to the MCU in the form of a digital signal and is written into the one-time programmable memory (OTP) for storage. Step 2: The stored data includes temperature values ​​and sensor register values. The temperature values ​​are in °C, while the sensor register values ​​are unitless but have a certain proportional relationship with the temperature values. 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 turned on, the microcontroller unit (MCU) reads the temperature calibration data and register value REG0 from the one-time programmable memory (OTP) via the I2C bus. Step 4: Read the current temperature register value REG1 and use the following formula to obtain the calibrated temperature value: In the above formula, 0.561 and 57 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. Add the OFFSET to T1' to obtain the actual operating temperature T1 of the display.

2. The temperature sensor calibration method for 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 a 9 / 10-bit Gamma data storage method to store Gamma data, storing 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 values ​​are stored in different byte locations.

3. The temperature sensor calibration method for an OLED microdisplay according to claim 1, characterized in that: The One-Time Programmable Memory (OTP) is a non-volatile memory.

4. The temperature sensor calibration method for an OLED microdisplay according to claim 1, characterized in that: The specific operation process of the one-time programmable memory (OTP) is as follows: Temperature calibration data is written at the factory: During the equipment manufacturing stage, the calibration data of the temperature sensor is written into the one-time programmable memory (OTP). Read data upon startup: Each time the OLED display is powered on, the microcontroller unit (MCU) reads the temperature calibration data from the one-time programmable memory (OTP) via the I2C bus. After reading the data, the 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 display's operating parameters in real time according to the compensation formula to ensure stable brightness.

5. An external temperature compensation method for an OLED microdisplay, characterized in that: The external temperature compensation method includes: temperature compensation formula determination and temperature compensation application; The steps for determining the temperature compensation formula include: Step 1: Place the microdisplay in the test platform and connect the probe and communication cable; Step 2: Set the temperature to -40 degrees Celsius. After stabilizing, send a command via computer to adjust Vcom to maintain the brightness level at the preset value, and record the Vcom and temperature values ​​at this time. Step 3: Repeat Step 2, gradually adjusting the temperature inside the test chamber 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. Step 4: Use a 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 fitting, a formula is obtained, which is as follows: T is the test temperature, and Vcom is the common voltage value required to maintain stable brightness at this temperature. Thus, the temperature compensation formula has been determined. The steps for applying temperature compensation include: Step 1: Calculate the current actual temperature value using the formula. To ensure stability, a window shift filter is applied. The formula is as follows: in REG1 is the temperature register value, and 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 based on the current actual temperature value T1, that is, calculate it according to the formula determined in "Temperature Compensation Formula Determination"; Step 3: The calculated Vcom value is transmitted to the display driver circuit via the I2C 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. Repeating the above steps periodically will enable the temperature compensation function.

6. The external temperature compensation method for an OLED microdisplay according to claim 5, 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 is adjusted, thereby controlling the luminous brightness.

7. The external temperature compensation method for an OLED microdisplay according to claim 5, characterized in that: The operation of using a fitting tool to perform quadratic function fitting on Vcom and the corresponding temperature value is as follows: Using temperature T as the independent variable and Vcom as the dependent variable, the fitting tool is selected, and a quadratic function model is chosen: Vcom = aT² + bT + c. The process of calculating the best-fit curve in MATLAB is as follows: 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); Substituting the fitted coefficients into the quadratic function model, we obtain the compensation formula: Substitute the known data points into the fitting formula, calculate the fitted value, compare it with the experimental value, and check the fitting accuracy.

8. The external temperature compensation method for an OLED microdisplay according to claim 5, characterized in that: The register value REG1 has a linear relationship with the actual temperature. The calibration data REG0 and T0 convert the current register value REG1 into the actual temperature value.

9. The external temperature compensation method for an OLED microdisplay according to claim 8, characterized in that: The specific steps in the temperature compensation process of OLED microdisplays are as follows: Step 1: During the operation of the display, the temperature sensor continuously monitors the ambient temperature and converts the collected temperature signal into a digital form, which is a register value REG. This register value has no unit, but it is proportional to the temperature. It is converted into the actual temperature value through a predetermined conversion formula. The microcontroller unit (MCU) receives the register value sent by the temperature sensor through the I2C bus. After receiving the data, the MCU will convert the register value into the actual ambient temperature value according to the preset temperature conversion formula: Temperature value = Register value * 0.561 - 57. 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 MCU will calculate a temperature deviation value ΔT = 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 MCU will use the deviation value to determine how to adjust the operating parameters of the display. Step 3: During the operation of the display, the microcontroller unit (MCU) records historical temperature data, including temperature change records since the display was turned on. This ensures that the MCU can obtain the trend of ambient temperature changes. The historical data is stored in the memory of the MCU as a circular cache for future prediction. Based on the recorded historical temperature data, the MCU analyzes the temperature change trend. Step 4: The microcontroller unit (MCU) uses linear regression to predict temperature changes over a future period. If the system detects that the temperature is gradually rising or falling, the MCU will adjust Vcom in advance. This prediction effectively avoids delayed response caused by temperature changes, making the brightness adjustment of the display smoother and more timely. Based on the predicted temperature change trend, the MCU will adjust the Vcom value in advance. Step 5: Based on the temperature deviation ΔT and historical temperature change trends, the microcontroller unit (MCU) calculates a compensation value. This compensation value determines the adjustment range of the Vcom value. The larger the temperature deviation, the larger the adjustment range of the Vcom value will be. The MCU adjusts the Vcom value on the display in real time according to the calculated compensation value. Step 6: After each Vcom value adjustment, the microcontroller unit (MCU) will monitor the brightness change of the display.

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