Types of Motor Encoders
The different encoders are based on how they generate the code or signal that drives the digital feedback mechanism.
The various types of motor encoders are:
Mechanical Encoder
Optical Encoder
Magnetic Encoder
Linear Potentiometer
They are also classified as to whether they are used on DC or AC motors.
DC motor encoder:
Linear Potentiometer (On/Off) Linear Potentiometer (Pulse Width Modulation) Optical Encoder Magnetic Encoder (Hall Effect and Magneto Resistive) Mechanical Encoders Zero Position Transducer(ZPT)
Optical Encoder: This is often called incremental encoders and is the most widely used form of encoding. They are sometimes referred to as resolvers, as the output is a series of pulses that represent the input shaft angle in steps. The optical encoder is an assembly that includes a lens, light-emitting diode (LED), and photodetector.
Mechanical Encoder
An inexpensive and popular form of encoding for DC motors uses mechanical contacts attached to the motor shaft. These are rotated past a stationary contact to generate a pulse train that is fed back to the controller. These are also called resolvers, as the output is a series of pulses that represent the input shaft angle in steps. They may be used with s wound-rotor DC motor or with an AC motor.
Magnetic Encoder
This type of encoder uses a ferromagnetic material with a known specific inductance. The material is attached to the motor shaft, and its inductance is changed as the rotor position changes. This inductance change generates a voltage proportional to the rotor angle, which can be used to generate a pulse train that is used as feedback.
Linear Potentiometer: This type of encoder consists of a potentiometer (variable resistor) wrapped around the rotating shaft driven by the motor with scale markings on the case. As the shaft rotates, the potentiometer’s resistance changes, and the control circuitry can count these changes to determine shaft angle. Also called on-off encoders, linear potentiometers are commonly used for DC motors where accuracy is not critical.
Zero Position Transducer (ZPT): This type of encoder is used primarily for servo applications where zero position must be maintained under a variety of load conditions. ZPTs include either an optical sensor or an inductive type encoder.
Rotary and linear encoder types are differentiated by the number of wires and joints involved in the mechanism.
Linear encoders have fewer connections than rotary encoders and therefore have a smaller number of wires, mostly a single pair. In order to distinguish them from rotary encoders, they are sometimes referred to as “linear with sloped axis” or “slant axis”.
The space between the bearings is one thing to consider. Encoders can be smaller and take up less space if they do not need any mechanical support.
Also, there will be cost differentials since parts will be less expensive on this type of encoding.
The encoders come in many shapes and sizes with a wide range of resolution, accuracies, and measurements. They are used on many machines to provide information that helps the machine run properly. Choosing the right one will help your machine perform as you want it to and keep your customers happy and returning.
What are the two main types of encoders?
There are two main types of position encoders: the rotary type, which is the most common, and the linear type. Rotary encoders are designed for use with a motor and rotating shaft, while linear encoders are designed to slide along a fixed track. The two types have several advantages and disadvantages that make them best suited for specific applications. In general, rotary encoders can handle greater operating speeds and higher capacities than linear encoders while maintaining accuracy and reliability.
