How do rotary encoder work？！

How do they work?

Magnetic encoder uses permanent magnets and magnetic sensors to detect movement and position. Typical building use magnets placed around the edge of the rotor disc connected to the shaft and positioning sensor detects changes in the magnetic field of the magnet poles alternately through.

The simplest configuration will have a magnet, its north and south poles opposing rotor, and a sensor. This device will produce a sine wave output frequency equal to the rotational speed of the shaft.

And a second sensor, provided in addition to the first 90 °, thus generating a cosine output, it is possible to detect not only the direction of rotation, can also be inserted into the absolute position of the sine and cosine of the shaft of the signal (Fig. 1). Incremental encoder, sinusoidal output of the sensor is converted to a square wave so coded orthogonal waveforms generated by one of the possible position angle only four. Greater resolution by increasing the number of sensors in the plurality of rotor poles through. For example, 1024 positions (or 10-bit resolution) can be achieved four sensors and 128 Poles.

1. A magnetic rotary encoder consists of two poles and two sensors. The second sensor can detect not only the direction of rotation can also insert the absolute position of the shaft.

1. A magnetic rotary encoder consists of two poles and two sensors. The second sensor can detect not only the direction of rotation can also insert the absolute position of the shaft.

Transparent and opaque areas of the optical encoder using a rotor disk of plastic or glass that can be detected by the rotating disc source and a photodetector. Like magnetic encoder, the simplest configuration is possible to use a sensor and a half of the disc transparent and half opaque. However, for higher resolution, the valve is usually divided into multiple segments (usually concentric) with two or more sensors.

Again rotor model, a suitable arrangement and position sensors provide quadrature output incremental encoder characteristics. Minimize the number of needles, the absolute encoder data is usually a serial output. While most commercial rotary encoder, the same principles of sensing and encoding can be applied to a linear encoder.

Previous：How to choose an encoder
Next：Rotary encoder defination