LED color temperature compensation method and device in high and low temperature environment based on FPGA, and storage medium

Abstract

The invention provides an FPGA (Field Programmable Gate Array)-based LED (Light Emitting Diode) color temperature compensation method in a high-low temperature environment, which comprises the following steps of: setting a proper current parameter for a color temperature index according to a protocol under a normal temperature condition, receiving a current correction parameter of a high-temperature pole and a current correction parameter of a low-temperature pole through a serial port communication module at high and low temperatures respectively, the received current correction parameters are stored through the EEPROM control module; after power-on, the temperature acquisition module reads the voltage digital quantity of a temperature sensor through an A / D port and converts the voltage digital quantity into temperature data, the EEPROM control module reads a current correction value and an initial current value from an EEPROM chip and outputs the current correction value and the initial current value to the color coordinate compensation module for calculation, the calculated value is output to the brightness control module, a PWM control signal is generated, and the brightness control module controls the brightness control module to work. And the compensated current values of the LED at different temperatures are obtained. The algorithm provided by the invention consumes less resources, is convenient to use, can effectively solve the problem of consistency of batch LED lamps, is realized by using pure logic, is convenient to transplant, and does not use an IP core of an FPGA (Field Programmable Gate Array).

Description

Technical Field

[0001] The present invention belongs to the technical field of airborne display, and in particular relates to an FPGA-based LED color temperature compensation method, device and storage medium in a high and low temperature environment. Background Art

[0002] With the development of display technology, a large number of new display media have emerged, such as OLED, miniLED and other displays. Although some indicators of new displays are more advantageous than LCD displays, they also have certain defects, such as short life and screen burn-in. Therefore, they still cannot completely replace LCD displays. Liquid crystal displays still occupy a large market share, especially in airborne applications, LCD is still the mainstream display medium.

[0003] In the field of airborne applications, the requirements for display quality and reliability technical indicators are constantly increasing, such as contrast, color temperature and other technical indicators. The color temperature indicator has a significant impact on the display effect, so the color temperature needs to be stable under three-temperature conditions. Due to the different luminous efficiency of LED lamps under three-temperature conditions, the color temperature indicator will drift, affecting the display effect. If the consistency is maintained by screening lamps, it will bring several times the cost. On this basis, a LED color temperature compensation method based on FPGA in high and low temperature environments is proposed. Summary of the invention

[0004] The present invention mainly provides an LED color temperature compensation method under high and low temperature environments based on FPGA. Under high and low temperature conditions, the compensation parameters pre-set in the EEPROM are read, and the current of the LED colored light is compensated according to the collected ambient temperature. The compensation algorithm is simple, practical, easy to implement, and consumes less resources.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: A method for compensating LED color temperature in high and low temperature environments based on FPGA includes the following steps: Under normal temperature conditions, the color temperature index is set to an appropriate current parameter according to the protocol, and the current correction parameters of the high temperature extreme and the low temperature extreme are received through the serial communication module at high and low temperatures respectively, and the received current correction parameters are stored in the EEPROM chip through the EEPROM control module; After power-on, the temperature acquisition module reads the digital voltage of the temperature sensor through the A / D port and converts it into temperature data. The EEPROM control module reads the current correction value and the initial current value from the EEPROM chip and outputs them to the color coordinate compensation module for calculation. The calculated value is output to the brightness control module to generate a PWM control signal to obtain the compensated current value of the LED at different temperatures.

[0006] Preferably, the color coordinate compensation module is used to implement an LED lamp current compensation algorithm, and the algorithm formula is as follows: (y- y0) / (x- x0) = (y1- y0) / (x1- x0); Among them, suppose the high temperature pole coordinate value is (x1, y1), the normal temperature coordinate value is (x0, y0), the current temperature value is x, and the compensation parameter value corresponding to x is y.

[0007] Preferably, the temperature acquisition module is used for A / D conversion, converting the analog voltage signal into a digital signal, the A / D conversion is implemented by using the IP core of XADC inside the FPGA, and converting the voltage signal into temperature data.

[0008] Preferably, the temperature acquisition module acquires the voltage of the backlight temperature sensor through the A / D port of the FPGA to identify the corresponding backlight environment temperature.

[0009] Preferably, the serial port communication module is used to receive data packets sent by the serial port, perform serial-to-parallel conversion, and parse data packet instructions and data.

[0010] Preferably, the EEPROM control module is used to store and read the current value of the normal temperature LED lamp and the correction parameter values ​​of the high and low temperature extremes in the EEPROM chip.

[0011] Preferably, the color coordinate compensation module is used to compensate according to the compensation parameters of the low temperature pole and the high temperature pole output by the EEPROM control module and the current parameters of the LED lamp at room temperature, and output the current parameters of the LED lamp at different temperatures.

[0012] Preferably, the brightness adjustment module outputs a PWM control signal according to the dimming control data of the serial port and the compensated current parameters of the LED lamp.

[0013] The present invention also provides an FPGA-based LED color temperature compensation device under high and low temperature environments, comprising a memory and a processor, the memory being used to store program data, and the processor being used to execute program data to implement the above-mentioned FPGA-based LED color temperature compensation method under high and low temperature environments.

[0014] The present invention also provides a computer-readable storage medium on which a computer program is stored. The computer program is loaded by a processor to execute the steps of the above-mentioned FPGA-based LED color temperature compensation method in high and low temperature environments.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The algorithm provided by the present invention consumes few resources, is easy to use, can effectively solve the consistency of batches of LED lamps, and the algorithm is implemented using pure logic, which is convenient for transplantation and does not use the IP core of the FPGA.

[0016] The present invention will be explained in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the principle of the present invention; Figure 2 It is the internal logic block diagram of the FPGA controller of the present invention; Figure 3 It is the IP core module of XADC of the present invention; Figure 4 It is a voltage and temperature curve diagram in the temperature acquisition module of the present invention; Figure 5 is a curve diagram of temperature compensation in the color coordinate compensation module of the present invention; Figure 6 It is the FPGA consumption resource table of the present invention. DETAILED DESCRIPTION

[0018] To facilitate understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings, but the present invention can be implemented in different forms and is not limited to the embodiments described in the text. On the contrary, these embodiments are provided to make the content disclosed in the present invention more thorough and comprehensive.

[0019] This embodiment provides a method for LED color temperature compensation in a high and low temperature environment based on FPGA, comprising the following steps: Under normal temperature conditions, the color temperature index is set with appropriate current parameters according to the protocol. The current correction parameters of the high temperature extreme and the low temperature extreme are received through the serial communication module at high and low temperatures respectively. The received correction parameters are stored in the EEPROM chip through the EEPROM control module. After power-on, the temperature acquisition module reads the digital voltage of the temperature sensor through the A / D port and converts it into temperature data. The EEPROM control module reads the correction value and initial current value from the EEPROM chip and outputs them to the color coordinate compensation module for calculation. The calculated value is output to the brightness control module to generate a PWM control signal, and the current value of the LED after compensation at different temperatures can be obtained. The internal logic block diagram of the FPGA controller is shown in the figure. Figure 1 shown.

[0020] Specifically, Figure 1 As shown, it is a schematic diagram of LED lamp driving and a schematic diagram of the principle of the present invention.

[0021] The PC described in the figure is generally a computer with a serial port debugging assistant, capable of sending serial port data, and a configurable baud rate.

[0022] The digital potentiometer described in the figure is used to adjust the output voltage value of the power supply.

[0023] The FPGA controller described in the figure is used to realize A / D conversion of temperature data, reception and return of serial port instructions, generation of brightness adjustment signals, reading and writing of EEPROM data, and compensation of LED lamp current parameters.

[0024] The EEPROM described in the figure is used to store the setting values ​​of parameters such as brightness parameters when power is off.

[0025] The backlight driving circuit described in the figure is used to control the LED lamp current.

[0026] The LED lamp described in the figure is a light emitting diode array, which provides a backlight source for a liquid crystal display.

[0027] In a preferred embodiment, the temperature acquisition module is used to convert the analog voltage signal into a digital signal by A / D conversion. The A / D conversion is implemented by the XADC IP core inside the FPGA. Figure 3 As shown, the resolution is 12-bit, and the voltage signal is converted into temperature data. The voltage and temperature curve VT curve is as follows Figure 4 shown.

[0028] In this embodiment, the serial communication module is mainly used to receive instructions and data such as brightness adjustment and color coordinate compensation parameters sent by the serial port.

[0029] In this embodiment, the EEPROM control module is used to store and read the current value of the normal temperature LED lamp and the correction parameter values ​​of the high and low temperature extremes in the EEPROM chip.

[0030] In this embodiment, the color coordinate compensation module is the core module of the present invention, which mainly realizes the LED lamp current compensation algorithm. Assume that the high temperature extreme point coordinate value is (x1, y1), the normal temperature coordinate value is (x0, y0), the current temperature value is x, and the compensation parameter value corresponding to x is y. Since the current change of the LED lamp is linear, a simple linear algorithm model can be used, as shown in the following formula: (y- y0) / (x- x0) = (y1- y0) / (x1- x0); The greatest difficulty of this algorithm lies in the division and signed calculation involved in the formula. If the division / or divider IP core is used for implementation, it will not only consume more resources, but also cause the timing to fail to converge, and may result in incorrect calculation results. Therefore, when implementing the above algorithm model, it is necessary to improve the above model to subtraction and multiplication calculations. Exchange and shift the calculation formula as follows: y = (y1- y0)* (x- x0) / (x1- x0) + y0; The implementation is as follows: First calculate the y1-y0 value.

[0031] The multiplier realizes (y1-y0)*(x-x0) and stores the value in register kx_reg.

[0032] By subtraction, subtract (x1-x0) from (y1-y0)*(x-x0) register kx_reg, and record the number of subtractions as div_n.

[0033] Then calculate y = div_n + y0, which is the final calculation result.

[0034] The corresponding temperature compensation curve is as follows: Figure 5 shown.

[0035] In this embodiment, the brightness control module is used for 255-level brightness adjustment and outputs a PWM control signal.

[0036] Through specific implementation, the resource table consumed by the FPGA provided by the present invention (FPGA device model: xc7a50tfgg484-2) is as follows Figure 6 shown.

[0037] From the above, it can be seen that the algorithm provided by the present invention consumes few resources, is easy to use, can effectively solve the consistency of batches of LED lights, and the algorithm is implemented using pure logic, which is convenient for transplantation and does not use the IP core of the FPGA.

[0038] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for LED color temperature compensation in high and low temperature environments based on FPGA, characterized in that: The steps include: Under normal temperature conditions, the color temperature index is set to an appropriate current parameter according to the protocol, and the current correction parameters of the high temperature extreme and the low temperature extreme are received through the serial communication module at high and low temperatures respectively, and the received current correction parameters are stored in the EEPROM chip through the EEPROM control module; After power-on, the temperature acquisition module reads the digital voltage of the temperature sensor through the A / D port and converts it into temperature data. The EEPROM control module reads the current correction value and the initial current value from the EEPROM chip and outputs them to the color coordinate compensation module for calculation. The calculated value is output to the brightness control module to generate a PWM control signal to obtain the compensated current value of the LED at different temperatures.

2. According to the FPGA-based LED color temperature compensation method in high and low temperature environments as described in claim 1, it is characterized in that: The color coordinate compensation module is used to implement the LED lamp current compensation algorithm, and the algorithm formula is as follows: (y- y0) / (x- x0) = (y1- y0) / (x1- x0); Among them, suppose the high temperature pole coordinate value is (x1, y1), the normal temperature coordinate value is (x0, y0), the current temperature value is x, and the compensation parameter value corresponding to x is y.

3. The LED color temperature compensation method under high and low temperature environment based on FPGA according to claim 1, characterized in that: The temperature acquisition module is used for A / D conversion, converting analog voltage signals into digital signals. The A / D conversion is implemented using the XADC IP core inside the FPGA, and converts the voltage signal into temperature data.

4. The LED color temperature compensation method under high and low temperature environment based on FPGA according to claim 1, characterized in that: The temperature acquisition module acquires the voltage of the backlight temperature sensor through the A / D port of the FPGA to identify the corresponding backlight environment temperature.

5. The LED color temperature compensation method under high and low temperature environment based on FPGA according to claim 1, characterized in that: The serial port communication module is used to receive data packets sent by the serial port, perform serial-to-parallel conversion, and parse data packet instructions and data.

6. The LED color temperature compensation method under high and low temperature environment based on FPGA according to claim 1, characterized in that: The EEPROM control module is used to store and read the current value of the normal temperature LED lamp and the correction parameter values ​​of the high and low temperature extremes in the EEPROM chip.

7. The LED color temperature compensation method under high and low temperature environment based on FPGA according to claim 1 or 6, characterized in that: The color coordinate compensation module is used to compensate according to the compensation parameters of the low temperature pole and the high temperature pole output by the EEPROM control module and the current parameters of the LED lamp at room temperature, and output the current parameters of the LED lamp at different temperatures.

8. The LED color temperature compensation method under high and low temperature environment based on FPGA according to claim 1, characterized in that: The brightness adjustment module outputs a PWM control signal according to the dimming control data of the serial port and the compensated current parameters of the LED lamp.

9. An LED color temperature compensation device based on FPGA in high and low temperature environments, characterized in that: It includes a memory and a processor, the memory is used to store program data, and the processor is used to execute the program data to implement the FPGA-based LED color temperature compensation method in a high and low temperature environment as described in any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and the computer program is loaded by a processor to execute the steps of the LED color temperature compensation method under high and low temperature environments based on FPGA according to any one of claims 1 to 8.

Images