Classification of photoelectric encoders and their characteristics

The photoelectric encoder is a digital sensor that integrates optical, mechanical and electrical technologies. It can measure the rotation angle or linear displacement of the object being measured with high precision and is currently the most widely used sensor.

Signal output schematic diagram

Classification of photoelectric encoders

Photoelectric encoders are divided into rotary encoders and ruler encoders according to the measuring method, and into absolute encoders, incremental encoders and hybrid encoders according to the encoding method.

Rotary encoder: measures the rotation angle of the object being measured and converts the measured rotation angle into a pulse electrical signal output.

Ruler encoder: measures the linear travel length of the object being measured and converts the measured travel length into a pulse electrical signal output.

Absolute rotary encoder

The Gray code scale on the dividing plate (the dividing plate is connected to the transmission shaft) is scanned with an optical signal to determine the absolute position value of the object being measured, and then the detected Gray code data is converted into an electrical signal to output the measured displacement in the form of pulses.

Features:

1. Different angles are encoded with different Gray codes within a detection cycle, so the position data output by the encoder is unique;

2. Due to the use of mechanical connection, the position of the encoder will not change when the power is off, and the current position data can be obtained immediately after power is on;

3. The detected data is Gray code, so there is no detection error of analog signal.

Incremental rotary encoders

The optical signal is used to scan the indexing disk (the indexing disk is connected to the rotating shaft), and the rotation angle is calculated by detecting and counting the number of on and off signals.

Features:

1. The encoder will output a pulse signal every time it rotates a preset angle. The rotation angle is calculated by counting the number of pulse signals. Therefore, the position data output by the encoder is relative;

2. Since a fixed pulse signal is used, the starting position of the rotation angle can be set arbitrarily;

3. Due to the use of relative encoding, the rotation angle data will be lost after power failure and needs to be reset.

Hybrid Rotary Encoders

The optical signal is used to scan the indexing disk (the indexing disk is connected to the rotating shaft), and the rotation angle is calculated by detecting and counting the number of on and off times of the optical signal; at the same time, the absolute rotation angle code and the relative rotation angle code are output.

Features: It has the uniqueness of the rotation angle encoding of an absolute encoder and the application flexibility of an incremental encoder.

Photoelectric encoders are mainly used in precision machinery manufacturing, automation engineering and packaging, precision electronics manufacturing, and other manufacturing engineering industries.