分别从几处扒的，希望大佬可以引用来改长点简单点
【what is a proximity sensor】
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact.
This sensing is done for two purposes:
1.increase energy efficiency by enabling the smartphone to turn off the LCD backlight
2.disable the touch screen to avoid accidental touches by the cheek
The proximity sensor usually sits up near the top speaker and combines an infrared LED and light detector to measure light levels, which tells the phone to lock the keys when its up to your ear and to activate wheh pulled away
Transmitter emits the IR Light signals and when this pair is close to some object, these Light signals gets reflected , which are received by IR detector LED. And depending upon the intensity of reflected light one can estimate how close/far the object is
【working princple】
【版本1】
Proximity detection based on infrared technology requires two components to form the optical front
end:
1. An infrared LED for the transmitter
2. A photo diode for the receiver
The IR LED in a proximity sensor transmits coded IR signals outwards through an aperture in the
mobile device. A target (e.g., the object we are trying to sense) in the vicinity of the mobile device
causes reflection of these IR signals. A portion of the reflected signal passes back through the
aperture and is captured by the photo diode. The reflected signals allow IR proximity sensors to
determine if there is an object within the cone of light generated by the aperture. Based on the intensity of the reception by the IR receiver, the output of the sensor is defined.
【版本2】
IR Sensors work by using a specific light sensor to detect a select light wavelength in the Infra-Red (IR) spectrum. By using an LED which produces light at the same wavelength as what the sensor is looking for, you can look at the intensity of the received light. When an object is close to the sensor, the light from the LED bounces off the object and into the light sensor. This results in a large jump in the intensity, which we already know can be detected using a threshold.
Detecting Brightness
Since the sensor works by looking for reflected light, it is possible to have a sensor that can return the value of the reflected light. This type of sensor can then be used to measure how "bright" the object is.
【PROS AND CONS】
Advantages:
High precision
Highly sensitive to surface reflection
Surface irregularities are detected
Reflected light colours are recognizable
Infrared detectors can receive the infrared light which is irradiated from both living and non-living objects
Infrared sensors can detect the infrared light from far distances over a large area
Disadvantages:
Irresistible to dirt, dust, ambient light colour and intensity
IR sensors have a number of disadvantages, including high power consumption, high cost, blind zones, and accumulation of dirt, as well as unreliable performance over temperature, hair, and skin color variations.
【what is a proximity sensor】
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact.
This sensing is done for two purposes:
1.increase energy efficiency by enabling the smartphone to turn off the LCD backlight
2.disable the touch screen to avoid accidental touches by the cheek
The proximity sensor usually sits up near the top speaker and combines an infrared LED and light detector to measure light levels, which tells the phone to lock the keys when its up to your ear and to activate wheh pulled away
Transmitter emits the IR Light signals and when this pair is close to some object, these Light signals gets reflected , which are received by IR detector LED. And depending upon the intensity of reflected light one can estimate how close/far the object is
【working princple】
【版本1】
Proximity detection based on infrared technology requires two components to form the optical front
end:
1. An infrared LED for the transmitter
2. A photo diode for the receiver
The IR LED in a proximity sensor transmits coded IR signals outwards through an aperture in the
mobile device. A target (e.g., the object we are trying to sense) in the vicinity of the mobile device
causes reflection of these IR signals. A portion of the reflected signal passes back through the
aperture and is captured by the photo diode. The reflected signals allow IR proximity sensors to
determine if there is an object within the cone of light generated by the aperture. Based on the intensity of the reception by the IR receiver, the output of the sensor is defined.
【版本2】
IR Sensors work by using a specific light sensor to detect a select light wavelength in the Infra-Red (IR) spectrum. By using an LED which produces light at the same wavelength as what the sensor is looking for, you can look at the intensity of the received light. When an object is close to the sensor, the light from the LED bounces off the object and into the light sensor. This results in a large jump in the intensity, which we already know can be detected using a threshold.
Detecting Brightness
Since the sensor works by looking for reflected light, it is possible to have a sensor that can return the value of the reflected light. This type of sensor can then be used to measure how "bright" the object is.
【PROS AND CONS】
Advantages:
High precision
Highly sensitive to surface reflection
Surface irregularities are detected
Reflected light colours are recognizable
Infrared detectors can receive the infrared light which is irradiated from both living and non-living objects
Infrared sensors can detect the infrared light from far distances over a large area
Disadvantages:
Irresistible to dirt, dust, ambient light colour and intensity
IR sensors have a number of disadvantages, including high power consumption, high cost, blind zones, and accumulation of dirt, as well as unreliable performance over temperature, hair, and skin color variations.
