An incremental encoder is an encoder device that converts the angular motion or position of a shaft into an analog or digital code to identify the position or movement. Incremental encoders are one of the most commonly used rotary encoders. Incremental encoders can be used in positioning and motor speed feedback applications including servo/light, industrial or heavy duty applications. Incremental encoders provide excellent speed and distance feedback, and since there are few sensors involved, the system is simple and inexpensive. Incremental encoders are limited to providing change information, so encoders need a reference device to calculate motion.
1. How do incremental encoders work? How Incremental Encoders Work!
Incremental encoders provide a specified number of pulses during one encoder revolution. The output can be a single line of pulses ("A" channel) or two lines of pulses ("A" and "B" channels), which are offset to determine rotation. This phase between the two signals is called quadrature. In incremental optical encoders, a typical assembly consists of a spindle assembly, a PCB and a cover. The PCB contains an array of sensors that create only the two main signals for position and velocity.
With incremental optical encoders, the optical sensor detects the light as it passes through the marked disc. The disc moves as the spindle assembly rotates, and the information is converted into pulses by the PCB. For incremental magnetic encoders, the optical sensor is replaced by a magnetic sensor, and the rotating disk contains a series of magnetic poles.
Optionally, additional signals can be provided:
The index or "Z" channel can be provided as a pulse per revolution signal for homing and pulse count verification on the A and/or B channels. This index can be gated in various states of A or B. It can also be non-gated and have different widths. Some encoders can also provide commutation (U, V, W) channels. These signals line up with the commutation windings on the servo motor. They also ensure that the drivers or amplifiers of these motors apply current to each winding in the correct order and at the correct level.
2. What products can the incremental rotary encoder replace with each other?
While incremental encoders are commonly used in many feedback applications, resolvers and absolute encoders offer alternatives depending on application requirements and environment.
* Incremental encoder and parser
Resolvers are electromechanical precursors to encoders, based on technology dating back to World War II. The current creates a magnetic field along the center winding. There are two mutually perpendicular windings. One winding is fixed in place and the other winding moves as the object moves. Changes in the strength and position of the two interacting magnetic fields allow the resolver to determine the motion of the object.
The simplicity of the resolver design allows it to operate reliably even under extreme conditions, from hot and cold temperature ranges to radiation exposure and even mechanical disturbances caused by vibration and shock. However, the parser's forgiving of source and application assembly comes at the expense of their ability to work in complex application designs, since it cannot produce sufficiently accurate data. Unlike incremental encoders, resolvers only output analog data, which may require specialized electronics to interface.
* Incremental encoder and absolute encoder
Absolute encoders work where speed and position accuracy, fault tolerance and interoperability are more important than system simplicity. An absolute encoder is able to "know where it is" based on its position in the event of a system power outage, and restarts if the encoder moves during the outage.
The absolute encoder itself knows positioning information - it does not need to rely on external electronics to provide a baseline index of the encoder's position. Especially compared to resolvers and incremental encoders, the clear advantage of absolute encoders is how their positioning accuracy affects the overall application performance, so it is often the encoder of choice for high-precision applications such as CNC, medical, and robotics.
3. The use and application of incremental encoder
Incremental encoders are designed to be versatile and customizable to suit a variety of applications. The three broad categories of applications based on environments are:
* Heavy Duty: Harsh environments with high potential for contamination and moisture, higher temperature, shock and vibration requirements, as seen in pulp, paper, steel and lumber mills.
* Industrial Applications: General factory operating environments that require standard IP ratings, moderate shock, vibration and temperature specifications as seen in food and beverage, textile, general factory automation factories.
* Lightweight/Servo: Controlled environments with high precision and temperature requirements, such as robotics, electronics, and semiconductors.