The photoelectric switch is controlled by converting the change of light intensity into the change of electric signal. ?

Generally speaking, photoelectric sensor consists of three parts, which are as follows:

A transmitter, a receiver and a detection circuit.

The transmitter aims at the target to emit light beams, which generally come from semiconductor light sources, light emitting diodes (LEDs) and laser diodes. Continuously emit light beams or change the pulse width.

The receiver consists of a photodiode or a phototransistor. In front of the receiver, optical elements such as lens and aperture are installed.

Behind it is a detection circuit, which can filter out effective signals and apply them.

◆ Classification and working methods?

1. Slotted photoelectric switch?

Groove photoelectric is to install a light emitter and a receiver face to face on both sides of a groove. The light emit can emit infrared light or visible light, and that light receiver can receive light without hindrance. But when the detected object passes through the slot, the light is blocked and the photoelectric switch acts. Output the switch control signal to cut off or turn on the load current, thus completing a control action. Due to the limitation of the overall structure, the detection distance of the slot switch is generally only a few centimeters. ?

2. Opposite photoelectric switch?

If the optical transmitter and the optical receiver are separated, the detection distance can be increased. The photoelectric switch composed of optical transmitter and optical receiver is called split photoelectric switch, which is referred to as opposite photoelectric switch for short. Its detection distance can reach several meters or even dozens of meters. When in use, the light emitter and the light receiver are respectively installed on both sides of the passing path of the detected object, and when the detected object passes, the light path is blocked, and the light receiver acts to output a switch control signal.

3. Reflective photoelectric switch with reflector?

Reflector-reflective (or mirror-reflective) photoelectric switch is a device that installs an optical transmitter and an optical receiver in the same device, installs a reflector in front of it, and uses the reflection principle to complete photoelectric control. Under normal circumstances, the light emitted by the light emitter is reflected by the reflector and received by the light receiver; Once the light path is blocked by the detected object, the optical receiver can't receive the light, and the photoelectric switch will act and output the switch control signal. ?

4. Diffuse reflection photoelectric switch?

Its probe is also equipped with a light emitter and a light receiver, but there is no reflector in front. In general, the light emitted by the light emitter cannot be received by the light receiver; When the detected object passes through, it blocks the light and partially reflects back the light, and the light receiver receives the light signal and outputs the switch control signal. ?

5. Optical fiber photoelectric switch?

Optical fiber photoelectric switch is to guide the light emitted by the optical transmitter to the detection point with optical fiber, and then guide the detected optical signal to the optical receiver with optical fiber.