A control circuit for automatically changing the brightness of a liquid crystal screen based on ambient light

Abstract

The utility model relates to display control circuit technical field, more particularly to a kind of control circuit based on ambient light automatic change liquid crystal screen brightness, including visible light signal acquisition circuit, infrared light signal acquisition circuit, main control module, liquid crystal screen brightness drive circuit.The utility model solves the technical problem that the display screen screen brightness is suddenly changed or continuously not suitable caused by the fact that sensor cannot accurately distinguish visible light and infrared light and is excessively sensitive or insensitive to infrared light in the prior art.

Description

Technical Field

[0001] This utility model relates to the field of display control circuit technology, and more specifically, to a control circuit that automatically changes the brightness of an LCD screen based on ambient light. Background Technology

[0002] Automatic brightness adjustment of displays plays a crucial role in human-computer interaction systems. In these systems, automatic brightness adjustment technology can dynamically adapt to changes in ambient light to optimize the visual experience and reduce energy consumption. This technology is widely used in automotive displays, mobile terminals, industrial instruments, and other applications.

[0003] Currently, the main automatic brightness adjustment technology for displays is based on ambient light sensors. Specifically, photodiodes or integrated ALS chips are used to collect ambient light intensity and transmit the data to a processor. The processor then outputs a PWM signal to adjust the display's backlight based on the input ambient light intensity data.

[0004] However, the aforementioned automatic brightness adjustment method for displays has certain drawbacks. In some scenarios, such as when a vehicle is rapidly entering / exiting a tunnel or a densely shaded road, the light sensor may be located below the dashboard or obstructed by the steering wheel, making it unable to accurately detect the instantaneous changes in strong light or shadow outside the windshield. Oversensitivity of the sensor to infrared light may result in excessively high screen brightness at sunset or insufficient brightness on cloudy days, causing sudden or persistently uncomfortable screen brightness changes. If an in-vehicle display has this problem, it will affect the driver's ability to read critical navigation information, posing a safety hazard. In summary, this invention proposes a control circuit that automatically adjusts the brightness of the LCD screen based on ambient light, aiming to solve the technical problem in existing automatic brightness adjustment technologies where sensors cannot accurately distinguish between visible and infrared light and are overly sensitive or insensitive to infrared light, causing sudden or persistently uncomfortable screen brightness changes. Utility Model Content

[0005] The purpose of this application is to provide a control circuit that automatically changes the brightness of an LCD screen based on ambient light, which solves the technical problem in the prior art where the sensor cannot accurately distinguish between visible light and infrared light and is overly sensitive or insensitive to infrared light, causing sudden changes or continuous discomfort in the brightness of the display screen.

[0006] To solve the above-mentioned technical problems, the solution adopted in this application is as follows:

[0007] A control circuit that automatically adjusts the brightness of an LCD screen based on ambient light includes a visible light signal acquisition circuit, an infrared light signal acquisition circuit, and a main control module;

[0008] The infrared light signal input terminal of the main control module is connected to the infrared light signal output terminal of the infrared light signal acquisition circuit to receive the infrared light signal transmitted by the infrared light signal acquisition circuit; the visible light signal receiving terminal of the main control module is connected to the visible light signal output terminal of the visible light signal acquisition circuit to receive the visible light signal from the visible light signal acquisition circuit.

[0009] The main control module adjusts the output PWM signal based on the received visible light and infrared light signals.

[0010] Preferably, the visible light signal acquisition circuit includes a visible light brightness sensor, a first operational amplifier U3.1, and a second operational amplifier U4.1;

[0011] One end of the visible light brightness sensor is grounded, and the other end is connected to the non-inverting input of the first operational amplifier U3.1, so that the current signal output by the visible light brightness sensor is input to the first operational amplifier U3.1; the signal output of the first operational amplifier U3.1 is connected to the non-inverting input of the second operational amplifier U4.1, so that the output signal of the first operational amplifier U3.1 is input to the positive input of the second operational amplifier U4.1.

[0012] Preferably, the infrared light signal acquisition circuit includes an infrared light intensity sensor U5, a third operational amplifier U6.1, and a fourth operational amplifier U7.1;

[0013] One end of the infrared light intensity sensor U5 is connected to the power supply, and the other end is connected to the non-inverting input of the third operational amplifier U6.1, so that the current signal output by the infrared light intensity sensor U5 is input to the third operational amplifier U6.1; the signal output terminal of the third operational amplifier U6.1 is connected to the non-inverting input terminal of the fourth operational amplifier U7.1, so that the output signal of the third operational amplifier U6.1 is input to the positive input terminal of the fourth operational amplifier U7.1.

[0014] Preferably, the control circuit for automatically changing the brightness of the LCD screen based on ambient light further includes an LCD screen brightness driving circuit; the LCD screen brightness driving circuit includes a driving chip U1 and an LCD screen.

[0015] The PWM signal output terminal of the driver chip U1 is connected to the PWM signal input terminal of the LCD screen, and the PWM signal input terminal of the driver chip U1 is connected to the PWM signal output terminal of the main control module. The driver chip U1 controls the brightness of the LCD screen by outputting PWM signals to the LCD screen.

[0016] Preferably, the PWM signal output terminal of the main control module is connected to the PWM signal input terminal of the driver chip U1 in the LCD screen brightness driving circuit, so that the driver chip U1 inputs a PWM signal and the driver chip U1 outputs a PWM signal to the LCD screen according to the received PWM signal, thereby adjusting the display brightness of the LCD screen in real time.

[0017] Preferably, the driver chip U1 is an MP3202.

[0018] Preferably, the visible light brightness sensor is model LX1970.

[0019] Preferably, the infrared light intensity sensor is model TSL26711; the main control module is model STM32F103C8T6.

[0020] The technical solution of this application has at least the following advantages and beneficial effects:

[0021] In existing LCD screen brightness adjustment technologies, the mainstream approach to distinguishing infrared and visible light is a single ambient light sensor combined with a filter. Different spectra are separated by the filter and then detected by the same sensor. This method relies on the filter's ability to filter different spectra, but the spectral cutoff characteristics of the filter cannot achieve complete filtering. For example, a filter used to separate visible light cannot completely block infrared light, resulting in infrared components mixed into the visible light detection signal. Furthermore, the same sensor needs to process the visible or infrared light signals separated by the filter in a time-division manner, resulting in low signal processing accuracy and susceptibility to noise and environmental interference. In some other solutions, infrared and visible light are separated later through algorithms. This method relies on algorithms to decompose the mixed spectrum and requires complex calibration models to eliminate cross-interference.

[0022] This invention features a visible light signal acquisition circuit and an infrared light signal acquisition circuit. By utilizing two independent dedicated sensors—an infrared brightness sensor and a visible light brightness sensor—physical-level spectral separation is achieved. This eliminates the need for spectral filtering with filters or post-processing algorithms, enabling more accurate detection of visible and infrared signals and preventing cross-interference between infrared and visible light at the sensor's source. In some scenarios, such as under the setting sun when infrared light is too strong, infrared interference can cause excessively high screen brightness. This design eliminates brightness misadjustment caused by infrared interference. Attached Figure Description

[0023] Figure 1 This is a circuit diagram of the visible light signal acquisition circuit in this utility model;

[0024] Figure 2 This is a circuit diagram of the infrared light signal acquisition circuit in this utility model.

[0025] Figure 3 This is a circuit diagram for driving the brightness of an LCD screen. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0027] It should be noted that similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. The terms "center," "upper," "lower," "inner," and "outer," indicating orientation or positional relationships based on the orientation or positional relationships shown in the figures, or the orientation or positional relationships commonly used when the product is in use, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed or operated in a specific orientation, and therefore should not be construed as a limitation on this application. It should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two elements. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0028] Example 1

[0029] This utility model provides a control circuit that automatically changes the brightness of an LCD screen based on ambient light, including a visible light signal acquisition circuit, an infrared light signal acquisition circuit, a main control module, and an LCD screen brightness driving circuit.

[0030] Further, see Figure 1 , Figure 1 This is a circuit diagram of the visible light signal acquisition circuit in this utility model. The visible light signal acquisition circuit includes a visible light brightness sensor, a first operational amplifier U3.1, a second operational amplifier U4.1, capacitors C3, C4, and C5, and resistors R3, R4, R5, and R6.

[0031] Specifically, one end of the visible light intensity sensor is grounded, and the other end is connected to the non-inverting input of the first operational amplifier U3.1, so that the current signal output by the visible light intensity sensor is input to the first operational amplifier U3.1; pin 4 of the first operational amplifier U3.1 is grounded to provide a zero-potential reference; pin 8 of the first operational amplifier U3.1 is connected to the power supply VCC, and one end of capacitor C5 is connected to the power supply VCC, while the other end is grounded, to stabilize the operating power supply of the first operational amplifier U3.1 and reduce the impact of power supply noise on the operational amplifier; the inverting input of the first operational amplifier U3.1... A feedback resistor R6 is connected between the first operational amplifier U3.1 and the signal output terminal. Resistor R6 forms the feedback path of the first operational amplifier U3.1, used to input a feedback signal to the inverting input terminal of the first operational amplifier U3.1, affecting the gain characteristics of the first operational amplifier U3.1. One end of capacitor C3 is connected to the signal output terminal of the first operational amplifier U3.1, and the other end is grounded, used to filter out interference signals in the output signal of the first operational amplifier U3.1. The grounded end of capacitor C3 is connected to one end of resistor R4, and the other end of resistor R4 is connected to the inverting input terminal of the second operational amplifier U4.1, thus connecting the first operational amplifier... The filtered output signal of U3.1 is input to the inverting input of the second operational amplifier U4.1. The signal output of the first operational amplifier U3.1 is connected to one end of resistor R3, and the other end of resistor R3 is connected to the non-inverting input of the second operational amplifier U4.1, directly inputting the output signal of the first operational amplifier U3.1 to the non-inverting input of the second operational amplifier U4.1. Pins 8 and 4 of the second operational amplifier U4.1 are left floating. A feedback resistor R5 is connected between the signal output and inverting input of the second operational amplifier U4.1, and resistor R5 constitutes the second operational amplifier U4.1. The feedback path is used to input a feedback signal to the inverting input terminal of the second operational amplifier U4.1, affecting the gain characteristics of the second operational amplifier U4.1; one end of capacitor C4 is connected to the signal output terminal of the second operational amplifier U4.1, and the other end is grounded, used to filter interference signals and noise in the output signal of the second operational amplifier U4.1; the signal output terminal of the second operational amplifier U4.1 is connected to the analog-to-digital conversion pin AD1 of the main control module. The signal output by the second operational amplifier U4.1 is an analog signal, which is input to the main control module to convert into a digital signal that can be further processed.

[0032] Specifically, the visible light brightness sensor is a photosensitizer that outputs different currents under different light intensities. When visible light illuminates the visible light brightness sensor, the current generated by the sensor is input to the non-inverting input of the first operational amplifier U3.1. Based on the virtual short and virtual open characteristics of the first operational amplifier U3.1, the potential of its inverting input follows that of its non-inverting input. Furthermore, the current flowing through resistor R6 is approximately equal to the output current of the visible light brightness sensor. Based on the characteristics and function of the first operational amplifier U3.1, the current signal from the visible light brightness sensor is converted into a voltage signal, and the signal is initially amplified. The output voltage signal of the first operational amplifier U3.1 is then divided by resistors R3 and R4 and input to the non-inverting and inverting inputs of the second operational amplifier U4.1, respectively. Based on the virtual short and virtual open characteristics of the second operational amplifier U4.1, the potential of the non-inverting input terminal of the second operational amplifier U4.1 is approximately equal to the potential of the inverting input terminal of the second operational amplifier U4.1; the signal output by the first operational amplifier U3.1 is amplified by the second operational amplifier U4.1 and then output. The capacitor C4 filters the output signal of the second operational amplifier U4.1 again, and finally outputs a stable voltage signal to the AD1 pin of the main control module.

[0033] Specifically, the visible light signal acquisition circuit acquires visible light signals from the environment. The visible light signal output terminal of the visible light signal acquisition circuit is connected to the visible light signal receiving terminal of the main control module, and the visible light signal is input to the main control module. The main control module adjusts the display brightness of the LCD screen according to the visible light signal.

[0034] It should be noted that the visible light brightness sensor in this utility model is model LX1970.

[0035] Further, see Figure 2 , Figure 2 This is a circuit diagram of the infrared light signal acquisition circuit in this utility model. The infrared light signal acquisition circuit includes an infrared light intensity sensor U5, a third operational amplifier U6.1, a fourth operational amplifier U7.1, capacitors C6, C7, and C8, and resistors R7, R8, R9, and R10.

[0036] Specifically, the infrared light signal acquisition circuit collects infrared light signals from the environment. The infrared light signal output terminal of the infrared light signal acquisition circuit is connected to the infrared light signal input terminal of the main control module, and the infrared light signal is input to the main control module. The main control module adjusts the display brightness of the LCD screen according to the infrared light signal.

[0037] It should be noted that the circuit structure for infrared light signal acquisition is the same as that for visible light signal acquisition, except that the visible light brightness sensor is replaced with an infrared light brightness sensor. Therefore, we will not repeat the description here.

[0038] It should be noted that the visible light brightness sensor in this utility model is model number TSL26711.

[0039] Further, see Figure 3 , Figure 3 This is a circuit diagram for driving the brightness of an LCD screen. The LCD screen brightness driving circuit includes a driver chip U1.

[0040] Specifically, the PWM signal output terminal of the driver chip U1 is connected to the PWM signal input terminal of the LCD screen, and the PWM signal input terminal of the driver chip U1 is connected to the PWM signal output terminal of the main control module. The driver chip U1 controls the brightness of the LCD screen by outputting PWM signals to the LCD screen.

[0041] It should be noted that in this utility model, the driver chip U1 is model MP3202.

[0042] Furthermore, the infrared light signal input terminal of the main control module is connected to the infrared light signal output terminal of the infrared light signal acquisition circuit to receive the infrared light signal transmitted by the infrared light signal acquisition circuit; the visible light signal receiving terminal of the main control module is connected to the visible light signal output terminal of the visible light signal acquisition circuit to receive the visible light signal from the visible light signal acquisition circuit.

[0043] Specifically, after receiving visible light and infrared light signals, the main control module adjusts the output PWM signal according to the ratio of the visible light and infrared light signals. The PWM signal output terminal of the main control module is connected to the PWM signal input terminal of the driver chip U1 in the LCD screen brightness driving circuit, inputting a PWM signal to the driver chip U1. The driver chip U1 then outputs a PWM signal to the LCD screen based on the received PWM signal, thereby controlling the display brightness of the LCD screen in real time.

[0044] It should be noted that the main control module is model STM32F103C8T6.

[0045] It should be noted that all the electronic devices mentioned in the above embodiments are available in domestic and international markets.

[0046] The various embodiments of this utility model have now been described in detail. To avoid obscuring the concept of this utility model, some details known in the art have not been described. Those skilled in the art will fully understand how to implement the technical solution of this utility model based on the above description. The scope of this utility model is defined by the appended claims.

Claims

1. A control circuit for automatically changing the brightness of an LCD screen based on ambient light, characterized in that: Includes optical signal acquisition circuit and main control module; The infrared light signal input terminal of the main control module is connected to the infrared light signal output terminal of the infrared light signal acquisition circuit to receive the infrared light signal transmitted by the infrared light signal acquisition circuit; the visible light signal receiving terminal of the main control module is connected to the visible light signal output terminal of the visible light signal acquisition circuit to receive the visible light signal from the visible light signal acquisition circuit. The main control module adjusts the output PWM signal based on the received visible light and infrared light signals.

2. The control circuit for automatically changing the brightness of a liquid crystal screen based on ambient light according to claim 1, wherein, The visible light signal acquisition circuit includes a visible light brightness sensor, a first operational amplifier U3.1, and a second operational amplifier U4.1; One end of the visible light brightness sensor is grounded, and the other end is connected to the non-inverting input of the first operational amplifier U3.1, so that the current signal output by the visible light brightness sensor is input to the first operational amplifier U3.1; the signal output of the first operational amplifier U3.1 is connected to the non-inverting input of the second operational amplifier U4.1, so that the output signal of the first operational amplifier U3.1 is input to the positive input of the second operational amplifier U4.

1.

3. The control circuit according to claim 1, wherein the control circuit is configured to change the brightness of the liquid crystal panel based on the ambient light. The infrared light signal acquisition circuit includes an infrared light intensity sensor U5, a third operational amplifier U6.1, and a fourth operational amplifier U7.1; One end of the infrared light intensity sensor U5 is connected to the power supply, and the other end is connected to the non-inverting input of the third operational amplifier U6.1, so that the current signal output by the infrared light intensity sensor U5 is input to the third operational amplifier U6.1; the signal output terminal of the third operational amplifier U6.1 is connected to the non-inverting input terminal of the fourth operational amplifier U7.1, so that the output signal of the third operational amplifier U6.1 is input to the positive input terminal of the fourth operational amplifier U7.

1.

4. The control circuit for automatically changing the brightness of a liquid crystal screen based on ambient light according to claim 1, characterized in that, It also includes a liquid crystal display brightness driving circuit; the liquid crystal display brightness driving circuit includes a driving chip U1 and a liquid crystal display. The PWM signal output terminal of the driver chip U1 is connected to the PWM signal input terminal of the LCD screen, and the PWM signal input terminal of the driver chip U1 is connected to the PWM signal output terminal of the main control module. The driver chip U1 controls the brightness of the LCD screen by outputting PWM signals to the LCD screen.

5. The control circuit for automatically changing the brightness of a liquid crystal screen based on ambient light according to claim 1, wherein, The PWM signal output terminal of the main control module is connected to the PWM signal input terminal of the driver chip U1 in the LCD screen brightness driving circuit. The driver chip U1 inputs a PWM signal to the driver chip U1, and the driver chip U1 outputs a PWM signal to the LCD screen according to the received PWM signal, thereby adjusting the display brightness of the LCD screen in real time.

6. The control circuit for automatically changing the brightness of a liquid crystal screen based on ambient light according to claim 5, wherein, The driver chip U1 is model MP3202.

7. The control circuit for automatically changing the brightness of a liquid crystal screen based on ambient light according to claim 2, wherein The visible light brightness sensor is model LX1970.

8. The control circuit for automatically changing the brightness of a liquid crystal screen based on ambient light according to claim 3, wherein, The infrared light intensity sensor is model TSL26711.

9. The control circuit for automatically changing the brightness of a liquid crystal screen based on ambient light according to claim 1, wherein, The main control module is an STM32F103C8T6.

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