What is photoelectric sensor？

Photoelectric sensor, also known as optical sensor,is thedevice that converts light signals into electrical signals. Photoelectric sensors are mainly divided into 3 categories: through-beam/opposed photo sensors, retro-reflective photo sensors/Mirror-reflective Sensorsanddiffused optical sensors. Moreover, the light source must be monochromatic, compact and durablein optical communication, and there are 2different types of light sourcesfor photoelectric sensors: infrared LED and laser. The main types of laser sensors are mirror reflection.

How photoelectric sensors work?

The optical sensorconsists of a transmitter, a receiver, and a detection circuit. Photoelectric sensors are controlled by translating changes in light intensity into changes in electrical signal. The purpose of an optical sensor is to measure the physical quantity of light depending on the type of sensor, and then convert it into a form that can be read by an integrated measuring device. Optical sensors are used for contact-less detection, counting, or positioning of parts, and theycan be internal or external. External sensors collect and transmit the required amount of light, while internal sensors are most often used to measure small changes in bending and other directions.

Main Categories of Photoelectric Sensor

Transmission mode

1. Through-beam Photocell Sensors/Opposed type Photoelectric Sensors

The system consists of two separate components, the emitter and the receiver, placed opposite each other. When using a pair of photoelectric switches the emitter and the receiver are mounted on either side of the path of passage of the detector, the detector blocks the light path when the detector passes and the receiver acts to output a switch-controlled signal. It does not matter where the interruption occurs.

Advantages and Features:

1. Highest accuracy among all types of optical sensors
2. Largest operating distance among all types of optical sensors
3. High operational dependability

4. Aspheric optics eliminate the interference of sunlight and stray light

2. Retro-reflective Sensors/Mirror-reflective Sensors

Transmitter and receiver are both in one house and the emitted beam is guided back to the receiver via a reflector. The interruption of the beam initiates a switching operation. It does not matter where the interruption occurs.

Advantages and Features:

1. Less cost comparing with opposed type
2. Operating distances larger than diffused type
3. High operational dependability
4. Less mounting effort

3. Diffused Reflection Photo Sensors

The transmitter and receiver are both in the same house. When a detected object passes by, the object reflects a sufficient amount of light emitted by the photoelectric sensor transmitter to the receiver. The photoelectric sensor thus generates a switching signal.

Advantages and Features:

(1) Mounted at only one point of the application (easy to install)

(2) Lower cost than opposed type and mirror-reflective sensors

Light Sources

1. Infrared LED type

Red LED indicates working status, easy for installation. Aspheric optical lens can eliminate stray light, and special optical structure has strong light resistance.

2. Laser type

Laser light has four unique characteristics that differentiate it from ordinary light: these are coherence, directionality, monochromatic and high intensity. It enables contactless measurement over long distances. Laser sensors are commonly used for measuring physical quantities such as length, distance, vibration, speed and orientation. Compared to conventional infrared photoelectric sensors, it has a longer detection distance and is more sensitive.

Application

The photoelectric sensors our company produced can be widely used in the door industryincluding revolving door, roller shutter door, commercial door, Industrial Suspended Sliding Gate, folding slide automatic gate; andintelligent parking