Incremental encoder

When mobile incremental encoder, the encoder will produce an axis rotation speed is proportional to (rotary encoder) or movement distance (linear encoder) binary pulse flow. Using optical encoders, placed in the LED light source and optical sensor between the specific style of the encoder or linear codes can take alternate conduction or block the beam, the resulting analog signal; Then additional circuit (usually) on-board ASIC will analog signal is converted to a square wave. Run magnetic encoders can be used in a variety of mechanisms, but will rotate a magnetic field, the resulting voltage pulse or can be converted into pulse resistance change.

Single channel only incremental encoder output pulse flow, therefore can only provide limited information. According to the resolution of the encoder, the number of pulses rotary encoder each lap or linear encoder sports movement distance (mm/inch), an external electronic device can undertake pulse counting, and calculate the speed or relative to a reference coordinate offset (starting point) and determine the encoder position. Single channel design for application such as one-way conveyor system provides excellent solutions.

Single channel encoder is simple, durable and economic price, but it has an important defect, is unable to determine the direction of motion. Determine direction need encoder have more output (usually adopts the phase difference of 90 ° dual channel design, to realize the channel "A" and "B" independent output). Due to the dual channel encoder signal output with two rising and falling edge, so sometimes referred to as the quadrature encoder. Decide which channel to reach high level movement direction, which makes the processor can easily monitor the direction of movement (see figure 1). Operator that is triggered by one or two channel pulse front and back along the encoder resolution - can improve the largest 4 times.

Quadrature encoder for challenging complex application provides a durable solution. In the application of high vibration, single channel encoder will likely be a relative to the set point of shaft jitter produced by pulse flow misinterpreted as a real displacement, quadrature encoder is able to identify the change of direction and ignore the pulse flow or as noise and filtered out.

Incremental encoder can also include an additional channels, or index channels (or Z channel). The channel can make the rotary encoder, or in a specific location of each lap to create a linear encoder pulse (see figure 2). Z channel can determine the specific location at startup. In high speed applications, the use of Z channel can easily indicate separate a circle, and the calculation speed.

Incremental encoder generally applies only to simple application, regardless of the control device is counters, PLC and frequency converter, connect directly to the encoder and the controller.