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Linear Light sensor
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Photoconductive resistance (hereinafter referred to as CdS) is a special kind of resistance, the abbreviation light resistance, alias optical tube. Its resistance and the strength of the light has a direct relation. The light intensity increases, the resistance decreases, Light intensity decreases, the resistance increases.
When a light ray, resistance within originally in a stable state of electronic is motivated to become free electrons. So the light is stronger, produce of free electrons are also more, the resistance will be small.
Dark resistance: when resistance in completely without radial illuminate condition (room temperature), says when resistance for dark resistance (when resistance stability constant, for example), and dark dump ohms resistor corresponding current as dark current.
Light resistance: when resistance in enough light irradiation condition (room temperature), says when resistance to light resistance (when resistance stability constant, for example one ohm), with bright resistance corresponding current as bright current.
While photo-current = light electricity - dark current
Of course we hope photoconductive resistance of high sensitivity, i.e. photo-current is bigger.
Linear Light Sensor
Photosensitive sensor is an photoconductive resistance characteristic of PN junction, has unilateral conductivity, so that the work should add reverse voltage. No light, there is a slight saturated reverse leakage current, namely the dark current sensor, when photosensitive deadline. When exposed to light, saturated reverse leakage current increase greatly, forming photo-current, which over incident light intensity changes. When a light ray PN junction, can make the PN junction produces in the electronic a hole for, make minority carriers increase of density. These carriers in reverse voltage drift, make reverse current increase. So can use light strength to change the current in the circuit.
In addition, photosensitive sensor has instead of photoconductive resistance characteristics, can follow a light changes linear output. And low dark current, low intensity of illumination, have a certain temperature stability. Meet the RoHS requirement.our products (lead-free/no cadmium).
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