Vehicle-mounted electronic outside rear-view mirror and display module thereof

Abstract

The embodiment of the utility model provides a vehicle-mounted electronic outside rear-view mirror and a display module thereof. The display module comprises a liquid crystal display screen and a display screen, the backlight driving unit is connected with the liquid crystal display screen and used for driving the liquid crystal display screen to work; the dimming unit is connected with the backlight driving unit and used for outputting a PWM dimming signal to adjust the driving current output by the backlight driving unit, and the dimming unit comprises a voltage sampling circuit provided with a voltage sampling point; one end of the temperature sensor is connected with the voltage sampling point and the other end is grounded; the main control chip is provided with a voltage sampling pin and a driving pin, and is internally provided with a data table for reflecting the corresponding relationship between the voltage value input by the voltage sampling pin and the duty ratio of the PWM dimming signal output by the driving pin; and the main control chip adjusts the duty ratio of the PWM dimming signal output by the PWM driving pin according to the actual voltage value input by the voltage sampling pin. The embodiment of the utility model can work normally when the environment temperature is relatively low.

Description

Technical Field

[0001] The embodiment of the utility model relates to the technical field of in-vehicle display circuits, and particularly to an in-vehicle electronic outside rearview mirror and a display module thereof. Background Art

[0002] The existing in-vehicle electronic outside rearview mirror mainly includes cameras respectively arranged on the outer sides of both sides of a motor vehicle and a display module installed in the cockpit of the motor vehicle and connected to the two cameras to display the shooting pictures of the two cameras. The display module further includes: a liquid crystal display screen; a backlight driving unit connected to the liquid crystal display screen for driving the liquid crystal display screen to work; and a dimming unit connected to the backlight driving unit for outputting a PWM dimming signal to adjust the driving current output by the backlight driving unit. However, when the ambient temperature is relatively low, the activity of the liquid crystal material in the liquid crystal display screen will also decrease, resulting in the phenomenon of delay and ghosting in the displayed picture, seriously affecting the driver's view of the road conditions on the side and rear of the vehicle. Summary of the Utility Model

[0003] The technical problem to be solved by the embodiment of the utility model is to provide a display module of an in-vehicle electronic outside rearview mirror, which can work normally in a low-temperature environment.

[0004] The technical problem to be further solved by the embodiment of the utility model is to provide an in-vehicle electronic outside rearview mirror, which can work normally in a low-temperature environment.

[0005] To solve the above technical problems, the embodiment of the utility model provides the following technical solutions: A display module of an in-vehicle electronic outside rearview mirror, including:

[0006] A liquid crystal display screen;

[0007] A backlight driving unit connected to the liquid crystal display screen for driving the liquid crystal display screen to work; and

[0008] A dimming unit connected to the backlight driving unit for outputting a PWM dimming signal to adjust the driving current output by the backlight driving unit, including:

[0009] A voltage sampling circuit provided with a voltage sampling point;

[0010] A thermistor with one end connected to the voltage sampling point and the other end connected to the ground terminal; and

[0011] The main control chip is respectively provided with a voltage sampling pin connected to the voltage sampling point and a driving pin connected to the backlight driving unit, and internally has a data table reflecting the corresponding relationship between the voltage value input by the voltage sampling pin and the duty cycle of the PWM dimming signal output by the driving pin. The main control chip adjusts the duty cycle of the PWM dimming signal output by the PWM driving pin according to the actual voltage value input by the voltage sampling pin.

[0012] Further, the voltage sampling circuit includes a power supply, a sampling resistor R, and a sampling capacitor C connected in series in sequence. One end of the sampling capacitor C far from the sampling resistor R is connected to the ground terminal, and the voltage sampling point is arranged on the line between the sampling resistor R and the sampling capacitor C.

[0013] Further, the thermistor is an NTC thermistor.

[0014] Further, the thermistor is attached to the back of the liquid crystal display screen.

[0015] On the other hand, to solve the above further technical problems, the embodiment of the present invention provides the following technical solution: An in-vehicle electronic exterior rearview mirror includes cameras respectively arranged on both sides outside the motor vehicle and a display module installed in the cab of the motor vehicle and connected to the two cameras to display the shooting pictures of the two cameras. The display module is the display module as described in any one of the above.

[0016] After adopting the above technical solution, the embodiment of the present invention has at least the following beneficial effects: By connecting a thermistor between the voltage sampling point of the voltage sampling circuit of the dimming unit and the ground terminal in the embodiment of the present invention, when the ambient temperature changes, the resistance value of the thermistor will also change accordingly, thereby changing the voltage value of the voltage sampling point. Then, after the main control chip collects the actual voltage value of the voltage sampling point through the voltage sampling pin, by comparing the actual voltage value with the internally stored data table, since the data table reflects the corresponding relationship between the voltage value input by the voltage sampling pin and the duty cycle of the PWM dimming signal output by the driving pin, through reasonable design of the data table, when the ambient temperature is relatively low, the positive duty cycle of the PWM dimming signal output by the driving pin is larger, that is, the driving current output by the backlight driving unit can be increased, and the brightness of the liquid crystal display screen is also higher, increasing its own temperature and ensuring the display effect of the liquid crystal display screen at low temperature. Description of the Drawings

[0017] Figure 1 It is a circuit principle block diagram of an optional embodiment of the in-vehicle electronic exterior rearview mirror of the present invention. Detailed Embodiment

[0018] The present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following illustrative embodiments and descriptions are only used to explain the present utility model and are not intended to limit the present utility model. Moreover, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0019] As Figure 1 shown, an optional embodiment of the present utility model provides a display module 1 for an in-vehicle electronic outside rearview mirror, including:

[0020] A liquid crystal display screen 10;

[0021] A backlight driving unit 12, connected to the liquid crystal display screen 10 for driving the liquid crystal display screen 10 to work; and

[0022] A dimming unit 14, connected to the backlight driving unit 12 for outputting a PWM dimming signal to adjust the driving current output by the backlight driving unit 12, including:

[0023] A voltage sampling circuit 141 provided with a voltage sampling point A;

[0024] A thermistor 143 with one end connected to the voltage sampling point A and the other end connected to the ground terminal; and

[0025] A main control chip 145, the main control chip 145 is respectively provided with a voltage sampling pin 1450 connected to the voltage sampling point A and a driving pin 1452 (IO port) connected to the backlight driving unit 12, and a data table reflecting the corresponding relationship between the voltage value input by the voltage sampling pin 1450 and the duty ratio of the PWM dimming signal output by the driving pin 1452 is built in. The main control chip 145 adjusts the duty ratio of the PWM dimming signal output by the PWM driving pin 1452 according to the actual voltage value input by the voltage sampling pin 1450.

[0026] In the embodiment of the present utility model, a thermistor 143 is connected between the voltage sampling point A of the voltage sampling circuit 141 of the dimming unit 14 and the ground terminal. When the ambient temperature is low, the resistance value of the thermistor 143 will also change accordingly, thereby changing the voltage value of the voltage sampling point A of the voltage sampling circuit 141. Furthermore, after the main control chip 145 collects the actual voltage value of the voltage sampling point A through the voltage sampling pin 1450, by comparing the actual voltage value with the built-in data table, since the data table reflects the corresponding relationship between the voltage value input by the voltage sampling pin 1450 and the duty cycle of the PWM dimming signal output by the driving pin 1452, through reasonable design of the data table, when the ambient temperature is low, the positive duty cycle of the PWM dimming signal output by the driving pin 1452 is larger, so that the driving current output by the backlight driving unit 12 increases, and the brightness of the liquid crystal display screen 10 is also higher, thereby increasing its own temperature and ensuring the display effect of the liquid crystal display screen 10 at low temperature.

[0027] In an alternative embodiment of the present utility model, as Figure 1 shown, the voltage sampling circuit 141 includes a power supply VDD, a sampling resistor R, and a sampling capacitor C connected in series in sequence. One end of the sampling capacitor C far from the sampling resistor R is connected to the ground terminal, and the voltage sampling point A is provided on the line between the sampling resistor R and the sampling capacitor C. In this embodiment, the voltage sampling circuit 141 is composed of a power supply VDD, a sampling resistor R, and a sampling capacitor C connected in series in sequence. The circuit structure is simple, and the voltage value of the voltage sampling point A is changed by the thermistor 143 to realize the change of the voltage with the ambient temperature.

[0028] When specifically designing the circuit, the supply voltage of the power supply VDD is 3.3V, the resistance value of the sampling resistor R is 4.7 kΩ, the zero-power resistance value of the NTC thermistor is 10 kΩ, and the actual voltage value ADC1 input by the voltage sampling pin 1450 = VDD / (R + NTC) * NTC; in addition, the corresponding relationship between the brightness of the liquid crystal display screen 10 and the actual voltage value ADC1 is as follows in the table:

[0029]

[0030] According to specific experimental measurements, the circuit of the embodiment of the present utility model can achieve brightness control of the liquid crystal display screen 10 at an ambient temperature of -40°C to 0°C.

[0031] In an alternative embodiment of the present utility model, the thermistor 123 is an NTC thermistor. In this embodiment, for the NTC thermistor, its resistance value decreases as the temperature increases. Therefore, when the ambient temperature is relatively low, its resistance value is relatively high, and the voltage across its two ends is relatively large. As a result, the actual voltage value of the voltage sampling point A collected by the main control chip 145 through the voltage sampling pin 1450 will be relatively smaller (usually lower than 4.5V). Thus, a main control chip 145 with a relatively small rated working voltage (such as a single-chip microcomputer) can be selected, and its cost is relatively lower. Moreover, when the temperature is relatively low, the sensitivity of the NTC thermistor to temperature change is relatively higher.

[0032] In an alternative embodiment of the present utility model, the thermistor 143 is attached to the back of the liquid crystal display screen 10. In this embodiment, the thermistor 143 is attached to the back of the liquid crystal display screen 10, enabling more accurate temperature detection of the liquid crystal display screen 10.

[0033] On the other hand, as Figure 1 shown, an embodiment of the present utility model provides a vehicle-mounted electronic outside rearview mirror, which includes cameras 3 respectively arranged on both sides outside the motor vehicle, and a display module 1 installed in the cab of the motor vehicle and connected to the two cameras 3 to display the captured images of the two cameras 3. The display module is the display module as described in any one of the above. In this embodiment, the vehicle-mounted electronic outside rearview mirror adopts the aforementioned display module 1, which can automatically increase the brightness for heating when the ambient temperature is relatively low.

[0034] The embodiments of the present utility model have been described above in conjunction with the accompanying drawings. However, the present utility model is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present utility model, those of ordinary skill in the art can also make many forms without departing from the spirit and scope protected by the claims of the present utility model. All of these fall within the protection scope of the present utility model.

Claims

1. A display module of a vehicle-mounted electronic outside rearview mirror, comprising: A liquid crystal display screen; A backlight driving unit connected to the liquid crystal display screen for driving the liquid crystal display screen to work; And A dimming unit connected to the backlight driving unit for outputting a PWM dimming signal to adjust the driving current output by the backlight driving unit; It is characterized in that the dimming unit includes: A voltage sampling circuit provided with a voltage sampling point; A thermistor with one end connected to the voltage sampling point and the other end connected to the ground terminal; and A main control chip, the main control chip is respectively provided with a voltage sampling pin connected to the voltage sampling point and a driving pin connected to the backlight driving unit, and a data table reflecting the correspondence between the voltage value input by the voltage sampling pin and the duty ratio of the PWM dimming signal output by the driving pin is built in, and the main control chip adjusts the duty ratio of the PWM dimming signal output by the PWM driving pin according to the actual voltage value input by the voltage sampling pin.

2. The display module of the in-vehicle electronic outside rearview mirror according to claim 1, characterized in that, The voltage sampling circuit includes a power supply, a sampling resistor R and a sampling capacitor C connected in series in sequence. One end of the sampling capacitor C far from the sampling resistor R is connected to the ground terminal, and the voltage sampling point is arranged on the line between the sampling resistor R and the sampling capacitor C.

3. The display module of the vehicle-mounted electronic outside rearview mirror according to claim 1, characterized in that The thermistor is an NTC thermistor.

4. The display module of the vehicle-mounted electronic outside rearview mirror according to any one of claims 1-3, characterized in that The thermistor is attached to the back of the liquid crystal display screen.

5. An in-vehicle electronic outside rearview mirror, comprising cameras respectively disposed on both sides outside a motor vehicle, and a display module installed in the cockpit of the motor vehicle and connected to the two cameras to display the captured images of the two cameras, characterized in that, The display module is the display module according to any one of claims 1-4.

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