Principle and application of ambient light sensor chip

The light distance sensor is also known as the ambient light sensor chip, which is used to measure the ambient light, the measurement of this level of light is carried out by photodiodes, through amplification, analog-to-digital conversion and other processing, the light energy is quantified. Through BB, WLED driver control and adjustment, the system can adjust the brightness of the display screen. If the area is lighter, the backlight will be reduced to save power, and it will give the user a comfortable experience. On the contrary, if it is in a brighter area, it will increase the brightness of the display backlight. The ambient light sensor will be designed to imitate the characteristics of the human eye's light sensing, and usually choose the green light spectrum band closest to the human eye's sensing as a reference, and its center band is 550nm.

When an object approaches the top of the sensor and enters the infrared light emitting area, some infrared rays will be reflected back to the sensor. The photodiode in the proximity sensor receives this reflected light. This allows the system to react to people or things approaching. A typical application is in the process of making a phone call, when the face is close to the screen, the screen will automatically turn off, and when the face leaves, it will automatically light up, which can save power and prevent misoperations caused by face touch.

Ambient light source:

1. Ambient light: Ambient light is a low-intensity light that is formed by multiple reflections of light through the surface of the surrounding environment. The ambient light can be used to describe the brightness of an area. Usually in a scene, the color of the ambient light is a constant. .

2. Point light source: The intensity of light emitted from a certain point in a limited space will attenuate with distance. The attenuation coefficient is generally the reciprocal of the second-degree polynomial of the distance.

3. Spotlight: It is characterized by the main illumination direction, the intensity attenuates with the distance, and the light attenuates outward along the center.

4. Sunlight: It is a directional light source, which is characterized by emitting light from infinity, the light is parallel, and the light intensity will not attenuate with the distance.

It is recommended that the optical distance sensing proximity sensor chip in the range-finding sensor chip series that Gongcai Electronics distributes from Taiwan-WH APS 4530A, WH4530A is a light-to-digital converter, which combines advanced ambient light sensors, advanced proximity sensor and high-efficiency infrared LED lights. The ambient light sensor (ALS) has a built-in filter to suppress infrared and provides a spectrum close to the response of the human eye. ALS can work from darkness to direct sunlight, and the selectable detection range is about 40dB. Dual-channel output (human eye and clear), so that ALS has a good light ratio under different lighting conditions. The proximity sensor (PS) has a built-in 940nm filter for anti-interference of ambient light, so the PS can detect reflected infrared light with high precision and excellent anti-interference. WH4530A has a programmable interrupt function, and has a threshold-based hysteresis for ALS and PS.