What is the function and working principle of photoelectric switch? What are the common types?

Photoelectric switch is a kind of sensor, which converts the change of light intensity between the transmitter and receiver into the change of current to achieve the purpose of detection. Photoelectric switch smoke alarm commonly used in security system is often used in industry to count the movement times of mechanical arm. This article has collected and collated some materials, hoping to be of great reference value to all readers.

Working principle and application of photoelectric switch

working principle:

Use optical elements to change the beam in the middle of the transmission medium; Use light beams to reflect objects; Make the beam return instantly after a long distance. Photoelectric switch is composed of transmitter, receiver and detection circuit. The transmitter aims at the target and emits a beam, which generally comes from light emitting diodes (LEDs) and laser diodes. The beam is emitted continuously, or the pulse width is changed. The radiation intensity of the pulse modulated beam is selected several times during the launch, and it runs towards the target without indirectly. The receiver consists of photodiodes or photodiodes. In front of the receiver, optical elements such as lens and aperture are installed. Behind it is the detection circuit, which can filter out effective signals and apply the signals.

Application:

Photoelectric switches have been used in many fields, such as crop position detection, liquid level control, product counting, width discrimination, speed detection, fixed-length shearing, hole recognition, signal delay, automatic door sensing, color code detection, punch and shear, and safety protection. In addition, using the concealment of infrared ray, it can also be used for anti-theft warning in banks, warehouses, stores, offices and other necessary occasions.

What is the function and working principle of photoelectric switch? What are the common types?

Several common photoelectric switches

1. Diffuse reflection photoelectric switch

Diffuse reflection photoelectric switch is a sensor that integrates transmitter and receiver. When a detected object passes by, enough light emitted by the photoelectric switch transmitter is reflected to the receiver, and the photoelectric switch generates a switch signal. When the surface of the detected object is bright or its reflectivity is extremely high, the diffuse reflection photoelectric switch is the preferred detection mode.

2. Mirror reflective photoelectric switch

The mirror-reflective photoelectric switch also integrates the transmitter and receiver. The light emitted by the photoelectric switch transmitter passes through the reflector and reflects back to the receiver. When the detected object passes through and completely blocks the light, the photoelectric switch generates the detection switch signal.

3. Opposed photoelectric switch

The opposed photoelectric switch consists of a transmitter and a receiver which are structurally separated from each other and whose optical axes are placed opposite each other. The light emitted by the transmitter directly enters the receiver. When the detected object passes between the transmitter and receiver and blocks the light, the photoelectric switch generates a switch signal. When the detected object is opaque, the photoelectric switch is the most reliable detection mode.

4. Trough photoelectric switch

The slot photoelectric switch is usually a standard U-shaped structure. Its transmitter and receiver are located on both sides of the U-shaped slot and form an optical axis. When the detected object passes through the U-shaped slot and blocks the optical axis, the photoelectric switch generates the detected switching signal. The slot type photoelectric switch is relatively safe and reliable, suitable for detecting high-speed changes and resolving transparent and translucent objects.

5. Optical fiber photoelectric switch

Optical fiber photoelectric switch uses plastic or glass optical fiber sensor to guide the light, so as to realize the detection that the detected object is not in the near area.