As we all know, the photoelectric sensor (photoelectric switch) is the abbreviation of the photoelectric proximity switch, which uses the shielding or reflection of the light beam by the detected object, and the circuit is turned on by the synchronization loop to detect the presence or absence of the object. With its high-quality characteristics, it is used in all aspects of production and life. However, many people do not understand or know about the photoelectric sensor in the process of using it, which reduces the work efficiency and destroys the work rhythm.
A photoelectric sensor is a sensor that uses a photoelectric device as a detection element. It first converts the measured non-electricity into a change in the amount of light, and then converts the corresponding amount of light into an electric amount through the optoelectronic device.
The photoelectric sensor uses the photoelectric effect of the photoelectric device to work.
These three photoelectric effects are mainly used.
(1) External photoelectric effect: the phenomenon that electrons of an object escape from the surface under the action of light. For example, photoelectric devices such as photoelectric tubes.
(2) Internal photoelectric effect: A phenomenon that can change the resistivity of an object under the action of light. For example, photoelectric devices such as photoresistors.
(3) The photoelectric effect of the barrier layer: the phenomenon that an object can generate an electromotive force in a certain direction under the action of light. For example, photovoltaic devices such as photovoltaic cells.
Photoelectric sensors are widely used in detection and control. They are basically divided into two categories: analog sensors and pulse sensors.
(1) Analog sensor: The photocurrent of the photoelectric device changes with the change of luminous flux. Such as photoelectric colorimetric pyrometer.
(2) Pulse sensor: The output of the photoelectric device has only two stable states, namely the switch state of "on" and "off", that is, the photoelectric device has an electrical signal output when it is illuminated, and when there is no light, there is no electrical signal output. For example, optical code disc sensor.
There are also CCD image sensors manufactured using charge-coupled device (CCD) photoelectric transfer and charge transfer.