Ambient light detection circuit for HUD (Head Up Display)

Abstract

The present invention discloses an ambient light detection circuit for an HUD (Head Up Display) and belongs to the automotive electronics field. The circuit mainly comprises a photosensitive triode T2; the collector of the photosensitive triode T2 is connected into VCC; the emitter of the photosensitive triode T2 is connected in series with a resistor R2 and thereafter is grounded; one path of thevoltage of the upper end of the R2, that is, the voltage of the non-grounding end of the R2, is directly connected to the A / D_1 end of an MCU, and the other path of the voltage is connected into an operational amplifier; and after the signals are amplified a certain number of times, the amplified signals are connected into the A / D_2 of the MCU. According to the ambient light detection circuit forthe HUD (Head Up Display) of the invention, one photoelectric conversion triode is adopted to achieve ambient light detection in a large dynamic range; and one sensor is adopted to acquire two pathsof signals to achieve ambient light detection in a large dynamic range; and therefore, the ambient light detection circuit has the advantages of low cost, high precision and wide dynamic range. Compared with the prior art, the ambient light detection circuit is lower in cost compared with the cost of a single rain quantity and brightness sensor, is more sensitive than a photosensitive diode and has a large acquisition range.

Description

[0001] Field [0002] The car head-up display (HUD, full name Head Up Display) is used to project important driving-related information on the windshield, reducing the distraction of sight while driving and improving safety. The invention discloses an ambient light detection circuit used for HUD, which belongs to the field of automotive electronics. Background technique [0003] Due to the large range of ambient light brightness changes during driving, HUD applications require a very high dynamic range to support daytime work with a brightness of more than 10,000 lx, and need to display images at 5 lx in a very dark night. [0004] If the ambient light cannot be detected well, the HUD image will either be unclear during the day or very dazzling at night. When entering a tunnel-like scene, the external ambient light changes greatly, and the HUD will suddenly become very dazzling, making the driver feel very uncomfortable. [0005] Therefore, the HUD display needs to be automa...

AI Technical Summary

Problems solved by technology

[0007] The present invention aims at the high cost of using the rain light sensor to detect ambient light in the prior art and is affected by the necessary configuration of the whole vehicle. The photosensitive diode is easy to be saturated, and it will be saturated when there is light in the morning. It is used for detection Indoor ambient light is fine, but it is not suitable to detect outdoor ambient light. A new ambient light detection circuit for HUD is proposed.

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