High and low temperature environment self-adaptive adjusting system for chromaticity and color temperature indexes of backlight module

Abstract

The utility model discloses a high and low temperature environment adaptive adjusting system for chromaticity and color temperature indexes of a backlight module. The high and low temperature environment adaptive adjusting system comprises a temperature acquisition circuit, a constant current source control circuit, a color compensation selection circuit, a control unit and the backlight module. The temperature acquisition circuit is connected with the control unit, the control unit is connected with the control end of the constant current source control circuit, and the output end of the constant current source control circuit is connected with an LED wafer circuit on a backlight lamp panel of the backlight module; the control unit is further connected with the control end of the color compensation selection circuit, and the color compensation selection circuit is connected with the FB feedback end of the constant current source control circuit. During working, the temperature condition of the backlight module is acquired in real time through the temperature acquisition circuit, and the control unit controls the on-off state of the MOS tube of each color compensation selection circuit according to the acquired temperature condition and a set day / night mode so as to adjust the magnitude of the output current of the corresponding constant current source circuit. And finally, the lighting state of each color of wafer circuit in the LED wafer circuit is adjusted.

Description

A high and low temperature environment adaptive adjustment system for the chromaticity and color temperature of a backlight module Technical Field

[0001] This utility model belongs to the field of display system technology, specifically relating to a high and low temperature environment adaptive adjustment system for the chromaticity and color temperature index of a backlight module. Background Technology

[0002] Colorimetry and color temperature are crucial optical performance indicators for display systems. In the full operating environment of a display system, variations in internal and external conditions can lead to operating requirements at extremely low and high temperatures. Under these conditions, the brightness-temperature curve of the LEDs in the backlight module causes significant changes in colorimetry and color temperature, impacting user experience and potentially leading to misinterpretations of information. Therefore, developing an adaptive adjustment system for the colorimetry and color temperature of the backlight module under high and low temperature environments is essential. Based on these considerations, an adaptive adjustment system for the colorimetry and color temperature of the backlight module under high and low temperature environments was designed. Summary of the Invention

[0003] The purpose of this invention is to design a high and low temperature environment adaptive adjustment system for the chromaticity and color temperature indicators of a backlight module, in order to solve the problem of chromaticity, color temperature and other indicators shifting when the display system changes with high and low temperature environments, thereby improving the user experience.

[0004] This utility model is achieved through the following technical solution:

[0005] A high and low temperature environment adaptive adjustment system for the chromaticity and color temperature index of a backlight module, the system comprising: a temperature acquisition circuit, a constant current source control circuit, a color compensation selection circuit, a control unit, and a backlight module;

[0006] The temperature acquisition circuit comprises three parts: a printed circuit board area temperature acquisition circuit, a backlight board area temperature acquisition circuit, and an LCD screen area temperature acquisition circuit. The printed circuit board area temperature acquisition circuit is located in the middle area of ​​the backlight control circuit printed circuit board of the backlight module, the backlight board area temperature acquisition circuit is located on the back of the backlight board of the backlight module, and the LCD screen area temperature acquisition circuit is close to the edge of the LCD screen. All three temperature acquisition circuits are connected to the control unit.

[0007] The control unit is connected to the control terminal of the constant current source control circuit, and the output terminal of the constant current source control circuit is connected to the LED chip circuit on the backlight board of the backlight module; the control unit is also connected to the control terminal of the color compensation selection circuit, and the color compensation selection circuit is connected to the FB feedback terminal of the constant current source control circuit.

[0008] In the above technical solution, the backlight module is the main light-emitting component of the display system, providing light sources for the display system in different modes. The backlight module mainly includes a structural frame, a backlight board, a backlight control circuit printed circuit board, a light guide plate, and optical film paper.

[0009] In the above technical solution, the temperature acquisition circuit is powered by an LDO power supply and a power filter circuit is set up. The power filter circuit can effectively filter out the influence of the medium and high frequency noise generated by the circuit on the temperature acquisition circuit.

[0010] In the above technical solution, the constant current source control circuit is divided into four control circuits: a constant current source circuit for the white chip, a constant current source circuit for the blue chip, a constant current source circuit for the orange chip, and a constant current source circuit for the green chip. Each constant current source circuit uses the domestically produced SGM3749 constant current source chip. The control terminals of these four constant current source control circuits are respectively connected to the four output PWM signal IO interfaces of the control unit, which are used to send the PWM signals controlling the four color chips to the constant current source circuits of the four color chips respectively.

[0011] In the above technical solution, the power input terminal of the SGM3749 domestic constant current source chip in each constant current source circuit is connected to the VCC 12V power supply terminal; the COMP pin of the SGM3749 domestic constant current source chip in each constant current source circuit is connected to a 47nF capacitor to compensate the converter and stabilize the chip operation; the SW and VIN terminals of the SGM3749 domestic constant current source chip in each constant current source circuit are connected to a 20uH inductor to detect the output voltage and realize the open-circuit LED protection function; the FB feedback terminal of the SGM3749 domestic constant current source chip in each constant current source circuit is connected to a detection resistor with an accuracy of 1% to ground. The current information is fed back by the voltage across the detection resistor to realize the control of the current and ultimately achieve the purpose of constant current control.

[0012] In the above technical solution, the color compensation selection circuit has three channels: a color compensation selection circuit for the blue chip, a color compensation selection circuit for the orange chip, and a color compensation selection circuit for the green chip. Each color compensation selection circuit uses an N-channel MOSFET to control its selection or shutdown. The drain of the MOSFET is connected to the FB feedback resistor, and the gate is connected to the control pin of the control unit. The FB feedback resistor of the blue chip color compensation selection circuit is connected to the FB feedback terminal of the blue chip constant current source circuit, the FB feedback resistor of the orange chip color compensation selection circuit is connected to the FB feedback terminal of the orange chip constant current source circuit, and the FB feedback resistor of the green chip color compensation selection circuit is connected to the FB feedback terminal of the green chip constant current source circuit.

[0013] In the above technical solution, the LED chip circuit includes four circuits: a white chip circuit, a blue chip circuit, an orange chip circuit, and a green chip circuit. The white chip circuit is connected to the output terminal of the constant current source circuit of the white chip, the blue chip circuit is connected to the output terminal of the constant current source circuit of the blue chip, the orange chip circuit is connected to the output terminal of the constant current source circuit of the orange chip, and the green chip circuit is connected to the output terminal of the constant current source circuit of the green chip.

[0014] In the above technical solution, each LED chip circuit adopts a combination of multiple chips in series and parallel. The appropriate chip distribution is calculated based on factors such as the actual size of the project and the status of the module.

[0015] The advantages and beneficial effects of this utility model are as follows:

[0016] The temperature acquisition circuit in this invention adopts a dual-path complementary approach, comprising three parts: a printed circuit board area temperature acquisition circuit, a backlight board area temperature acquisition circuit, and an LCD screen area temperature acquisition circuit. Under high temperature, normal temperature, and low temperature conditions, the temperatures acquired from two of the three parts are weighted and processed. This complementary acquisition method avoids temperature misjudgment and improves acquisition accuracy. During operation, the temperature acquisition circuit collects the temperature of the backlight module in real time. The control unit, based on the collected temperature and the set day / night mode (which can be set by the host computer to the control unit), controls the switching state of the MOS transistors in each color compensation selection circuit to adjust the output current of the corresponding constant current source circuits, ultimately adjusting the illumination state of each color chip circuit in the LED chip circuit.

[0017] This invention integrates domestically produced constant current source control circuit and color compensation selection circuit, featuring a wide temperature adaptability range, smooth adjustment curve, and high sensitivity. The high and low temperature environment adaptive adjustment system for the backlight module's chromaticity and color temperature indicators solves the problem of severe optical index deviation caused by changes in high and low temperatures, and resolves the conversion problem between the differences in temperature-brightness change curves of different colored LEDs and the nonlinear adjustment of optical indicators, effectively improving the stability of the display screen's optical effect and user experience. Attached Figure Description

[0018] Figure 1 is a schematic diagram of the overall block diagram of this utility model.

[0019] Figure 2 is a circuit diagram of the temperature acquisition circuit.

[0020] Figure 3 is a circuit diagram of the constant current source control circuit.

[0021] Figure 4 is the circuit diagram of the color compensation selection circuit.

[0022] Figure 5 is a circuit diagram of an LED chip circuit. Detailed Implementation

[0023] The technical solution of this utility model will be further illustrated below with specific examples.

[0024] Referring to Figure 1, this embodiment provides a high and low temperature environment adaptive adjustment system for the chromaticity and color temperature index of a backlight module. The system includes: a temperature acquisition circuit, a constant current source control circuit, a color compensation selection circuit, a control unit, and a backlight module.

[0025] The backlight module is the main light-emitting component of a display system, providing light sources for different display modes. The backlight module mainly includes a structural frame, backlight board, backlight control circuit printed circuit board, light guide plate, optical film paper, etc., and performs functions such as backlight output, light mixing, light homogenization, and light filtering.

[0026] Referring to Figure 2, the temperature acquisition circuit adopts a dual-path complementary configuration, comprising three parts: a printed circuit board (PCB) area temperature acquisition circuit, a backlight board area temperature acquisition circuit, and an LCD screen area temperature acquisition circuit. The PCB area temperature acquisition circuit is located in the middle area of ​​the backlight control circuit PCB. Its first temperature-sensitive resistor is connected to the ADC acquisition I / O port of the control unit, enabling it to acquire temperature information from the PCB, providing high accuracy under both normal and high temperature conditions. The backlight board area temperature acquisition circuit is located on the back of the backlight board, which is at the core of the backlight module. Its second temperature-sensitive resistor is connected to the ADC acquisition I / O port of the control unit, enabling it to acquire temperature information from the backlight board (backlight module), providing high accuracy under both normal and high temperature conditions. The LCD screen area temperature acquisition circuit is located close to the edge of the LCD screen. Its third temperature-sensitive resistor is connected to the ADC acquisition I / O port of the control unit, enabling it to acquire temperature information from the LCD screen, providing high accuracy under both normal and low temperature conditions. Under three conditions—high temperature, normal temperature, and low temperature—two of the collected temperatures from each of the three parts are selected for weighted processing. This complementary acquisition method avoids temperature misjudgment and improves the accuracy of the data collection.

[0027] In low-temperature environments, the temperature collected by the LCD screen area temperature acquisition circuit, which has higher low-temperature accuracy, is used, and then weighted and calculated with the temperature collected by the printed circuit board area temperature acquisition circuit before being used in the compensation dimming algorithm calculation. In high-temperature environments, the temperature collected by the backlight board area temperature acquisition circuit, which has higher high-temperature accuracy, is used, and then weighted and calculated with the temperature collected by the printed circuit board area temperature acquisition circuit before being used in the compensation dimming algorithm calculation.

[0028] Furthermore, the temperature acquisition circuit is powered by an LDO power supply and is equipped with a power filter circuit. The power filter circuit can effectively filter out the influence of mid-to-high frequency noise generated by the circuit on the temperature acquisition circuit.

[0029] Referring to Figure 3, the constant current source control circuit is divided into four control circuits: one for the white LED, one for the blue LED, one for the orange LED, and one for the green LED. Each constant current source circuit uses the domestically produced SGM3749 constant current source chip, which has advantages such as small size, high efficiency, low quiescent current, and good dynamic response. During design, the input voltage of the constant current source circuit needs to be set according to the characteristics and arrangement of the LED chips. For example, according to Figure 5, the white LEDs in the backlight board are arranged in 9 series and 5 parallel configurations, while the colored LEDs (blue, orange, and green) are arranged in 7 series and 2 parallel configurations. Based on the chip characteristics, the minimum output voltage of the constant current source must be higher than 12.6V to drive the backlight board normally. Considering the boost characteristics of the constant current source, the input voltage is set to 12V. The control terminals of these four constant current source control circuits are respectively connected to the IO interfaces of the four output PWM signals of the control unit (preferably, the control unit uses a domestic GD32F103 microcontroller). The frequency, period, duty cycle and other states of each PWM signal can be configured according to the user's needs, and the PWM signals controlling the four-color chips are sent to the constant current source circuits of the four-color chips respectively.

[0030] For example, taking the constant current source circuit of a white semiconductor as an example, its specific circuit structure is as follows:

[0031] The control terminal (CTRL terminal) of the SGM3749YTN6G constant current source chip is connected to the I / O interface F_PWM_WLED of the control unit to receive the PWM dimming signal sent by the control unit. The power input terminal (VIN terminal) of the SGM3749YTN6G constant current source chip is connected to the VCC12V power supply terminal to provide the power required for chip operation. A 47nF capacitor is connected to the COMP pin of the SGM3749YTN6G constant current source chip to compensate the converter and stabilize the chip operation. A 20uH inductor is connected between the SW and VIN terminals of the SGM3749YTN6G constant current source chip to detect the output voltage and realize the open-circuit LED protection function. The FB feedback terminal of the SGM3749YTN6G constant current source chip is connected to a 1R sensing resistor with an accuracy of 1% to ground. The current information is fed back by detecting the voltage on the resistor to realize the current control and ultimately achieve the purpose of constant current control.

[0032] Referring to Figure 4, the color compensation selection circuit comprises three channels: a color compensation selection circuit for the blue chip, a color compensation selection circuit for the orange chip, and a color compensation selection circuit for the green chip. Each color compensation selection circuit uses an N-channel MOSFET to control its on / off state. The drain of the MOSFET is connected to the FB feedback resistor, and the gate is connected to the control pin of the control unit. The control unit controls the switching of the MOSFET in each color compensation selection circuit. The FB feedback resistor of the blue chip color compensation selection circuit is connected to the FB feedback terminal of the blue chip constant current source circuit, the FB feedback resistor of the orange chip color compensation selection circuit is connected to the FB feedback terminal of the orange chip constant current source circuit, and the FB feedback resistor of the green chip color compensation selection circuit is connected to the FB feedback terminal of the green chip constant current source circuit. By controlling the switching state of each MOSFET and pre-configuring the resistance value of the FB feedback resistor in each color compensation selection circuit, the output current of the corresponding constant current source circuit is adjusted, ultimately adjusting the brightness level of each color chip circuit in the LED chip circuit.

[0033] For example:

[0034] When the blue component in the backlight module is too low and the blue chip needs to participate in blue light compensation, the control unit controls the MOSFET in the color compensation selection circuit of the blue chip to turn on. At this time, the feedback resistor connected to the drain of the MOSFET is in parallel with the feedback resistor in the blue constant current source circuit, which reduces the resistance value of the FB feedback resistor on the FB pin in the blue constant current source circuit, increases the output current of the blue chip constant current source circuit (that is, increases the current driving the blue chip), increases the proportion of blue light, and achieves the purpose of blue light compensation for the backlight module.

[0035] Referring to Figure 5, the backlight board of the backlight module is equipped with LED chip circuits, which include four channels: white chip circuit, blue chip circuit, orange chip circuit, and green chip circuit. The white chip circuit is connected to the output terminal of the constant current source circuit of the white chip, the blue chip circuit is connected to the output terminal of the constant current source circuit of the blue chip, the orange chip circuit is connected to the output terminal of the constant current source circuit of the orange chip, and the green chip circuit is connected to the output terminal of the constant current source circuit of the green chip. Each channel adopts a combination of multiple chips in series and parallel. The appropriate chip distribution is calculated based on factors such as the actual size of the project and the status of the module.

[0036] For example:

[0037] The main parameters of white chips are: operating voltage of approximately 2.8V-3.6V, operating current not exceeding 30mA, and a 5-parallel-9-series configuration (i.e., 5 strings of white chips connected in parallel, with each string consisting of 9 white chips connected in series); the main parameters of blue chips are: operating voltage of approximately 2.6V-3.1V, operating current not exceeding 40mA, and a 2-parallel-7-series configuration (i.e., 2 strings of blue chips connected in parallel, with each string consisting of 7 blue chips connected in series). The main parameters of the orange chips are: operating voltage of approximately 2.7V-3.0V, operating current not exceeding 20mA, and a 2-parallel-7-series distribution (i.e., two strings of orange chips are connected in parallel, and each string of orange chips consists of seven orange chips connected in series); the main parameters of the green chips are: operating voltage of approximately 1.8V-2.1V, operating current not exceeding 30mA, and a 2-parallel-7-series distribution (i.e., two strings of green chips are connected in parallel, and each string of green chips consists of seven green chips connected in series).

[0038] During operation, the temperature of the backlight module is collected in real time through the temperature acquisition circuit. The control unit controls the switching state of the MOS transistors of each color compensation selection circuit according to the collected temperature and the set day / night mode (the day / night mode can be set by the host computer to the control unit), thereby adjusting the output current of each constant current source circuit and ultimately adjusting the lighting state of each color chip circuit in the LED chip circuit.

[0039] For example, when the backlight module operates at a low temperature, the control unit controls the MOSFETs of the color compensation selection circuits for the blue and orange chips to turn on, thereby adjusting and compensating the blue and orange chips. When operating at a high temperature, the control unit controls the MOSFETs of the color compensation selection circuits for the blue and green chips to turn on, thereby adjusting and compensating the blue and green chips. The adjustment of the compensation amount is directly achieved using the PWM control signal in the constant current source control circuit.

[0040] The present invention has been described above by way of example. It should be noted that, without departing from the core of the present invention, any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort fall within the protection scope of the present invention.

Claims

1. A high and low temperature environment adaptive adjustment system for the chromaticity and color temperature index of a backlight module, characterized in that: The system includes: a temperature acquisition circuit, a constant current source control circuit, a color compensation selection circuit, a control unit, and a backlight module. The temperature acquisition circuit comprises three parts: a printed circuit board area temperature acquisition circuit, a backlight board area temperature acquisition circuit, and an LCD screen area temperature acquisition circuit. The printed circuit board area temperature acquisition circuit is located in the middle area of ​​the printed circuit board containing the backlight control circuit of the backlight module; the backlight board area temperature acquisition circuit is located on the back of the backlight board of the backlight module; and the LCD screen area temperature acquisition circuit is located close to the edge of the LCD screen. All three temperature acquisition circuits are connected to the control unit. The control unit is connected to the control terminal of the constant current source control circuit, and the output terminal of the constant current source control circuit is connected to the LED chip circuit on the backlight board of the backlight module. The control unit is also connected to the control terminal of the color compensation selection circuit, and the color compensation selection circuit is connected to the FB feedback terminal of the constant current source control circuit.

2. The high and low temperature environment adaptive adjustment system for the chromaticity and color temperature index of the backlight module according to claim 1, characterized in that: The backlight module includes a structural frame, a backlight board, a backlight control circuit printed circuit board, a light guide plate, and an optical film.

3. The high and low temperature environment adaptive adjustment system for the chromaticity and color temperature index of the backlight module according to claim 1, characterized in that: The temperature acquisition circuit is powered by an LDO power supply and a power filtering circuit is included.

4. The high and low temperature environment adaptive adjustment system for the chromaticity and color temperature index of the backlight module according to claim 1, characterized in that: The constant current source control circuit is divided into four control circuits: a constant current source circuit for the white chip, a constant current source circuit for the blue chip, a constant current source circuit for the orange chip, and a constant current source circuit for the green chip. Each constant current source circuit uses the domestically produced SGM3749 constant current source chip. The control terminals of these four constant current source control circuits are respectively connected to the four output PWM signal IO interfaces of the control unit.

5. The high and low temperature environment adaptive adjustment system for the chromaticity and color temperature index of the backlight module according to claim 4, characterized in that: The power input terminal of the SGM3749 domestic constant current source chip in each constant current source circuit is connected to the VCC 12V power supply terminal; the COMP pin of the SGM3749 domestic constant current source chip in each constant current source circuit is connected to a 47nF capacitor; the SW and VIN terminals of the SGM3749 domestic constant current source chip in each constant current source circuit are connected to a 20uH inductor; and the FB feedback terminal of the SGM3749 domestic constant current source chip in each constant current source circuit is connected to ground with a detection resistor with an accuracy of 1%.

6. The high and low temperature environment adaptive adjustment system for the chromaticity and color temperature index of the backlight module according to claim 4, characterized in that: The color compensation selection circuit consists of three channels: a color compensation selection circuit for the blue chip, a color compensation selection circuit for the orange chip, and a color compensation selection circuit for the green chip. Each color compensation selection circuit uses an N-channel MOSFET to control its selection or shutdown. The drain of the MOSFET is connected to the FB feedback resistor, and the gate is connected to the control pin of the control unit. The FB feedback resistor of the blue chip color compensation selection circuit is connected to the FB feedback terminal of the blue chip constant current source circuit, the FB feedback resistor of the orange chip color compensation selection circuit is connected to the FB feedback terminal of the orange chip constant current source circuit, and the FB feedback resistor of the green chip color compensation selection circuit is connected to the FB feedback terminal of the green chip constant current source circuit.

7. The high and low temperature environment adaptive adjustment system for the chromaticity and color temperature index of the backlight module according to claim 4, characterized in that: The LED chip circuit includes four circuits: a white chip circuit, a blue chip circuit, an orange chip circuit, and a green chip circuit. The white chip circuit is connected to the output terminal of the constant current source circuit of the white chip, the blue chip circuit is connected to the output terminal of the constant current source circuit of the blue chip, the orange chip circuit is connected to the output terminal of the constant current source circuit of the orange chip, and the green chip circuit is connected to the output terminal of the constant current source circuit of the green chip.

8. The high and low temperature environment adaptive adjustment system for the chromaticity and color temperature index of the backlight module according to claim 7, characterized in that: Each LED chip circuit uses multiple chips connected in series and parallel.

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