The photoelectric sensor (photoelectric switch) is also an abbreviation of photoelectric proximity switch. It uses the object to block or reflect the light beam, and the circuit is connected by the synchronous loop to detect the presence or absence of the object. Objects are not limited to metal. All objects that can reflect light (or block light) can be detected. The photoelectric switch converts the input current into a light signal on the transmitter and emits it. The receiver then detects the target object based on the intensity of the received light or the presence or absence of the light. Photoelectric switch smoke alarms commonly used in security systems are often used in industry to count the number of movements of a robotic arm.

Photoelectric switches are divided into two types: reflective and direct type:

The alignment of the direct axis of the photoelectric switch between the receiver and the transmitter must be strictly required. When an object passes through it, the infrared beam is also blocked. At this time, the receiver cannot receive the pulse signal. The detection distance of the direct-type switch is very long, and some can reach more than ten meters. As long as the luminous object blocks the light, it can be detected.

The reflective type of the photoelectric switch is a more convenient one-sided installation type, but if you want to achieve better results, you need to adjust the angle of the mirror. The triangular prism is also what we call a mirror. The angle of the mirror is not sensitive to changes, and sometimes a polarizer is used as needed. The reason for choosing a polarizer is that it can transform the received light source into polarized light, thereby improving the ability to resist interference. In application, the photoelectric switch has a very definite area, and the objects around the area will not cause the photoelectric switch to generate a pulse signal to generate the switch indication. The LED used by the photoelectric switch is basically driven by narrow pulses and intermediate frequency currents, so it emits light pulses of small HZ. At the same time, the original receiving light is processed with an amplifier or a special chip. , The interference of sunlight, the power consumption of the LED has been reduced again.

When the diffuse reflection type photoelectric switch is working, the light emitted is very strict on the surface of the measured object, the surface is smooth enough, and the angle is also required when testing, and it is required to be perpendicular to the object.