Technical Guides

What is Encoder?

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If you are in mechanics, it will not be strange with the concept of Encoder? The encoder is a device used in many automation industries. It is also an important part of the structure diagram of a CNC machine. You will find Encoders used in cutting applications, plotters and more. You may have never noticed, but the Encoder is always there. However, not everyone knows what an encoder is? Application of the Encoder, how does it work? Encoder has 1 type or many types? Join me to find out what you need to know about Encoder!

1. What is the encoder?

+ An encoder, also known as an encoder, is a mechanical motion sensor that generates a digital signal in response to motion. An electromechanical device that converts motion into a digital signal or pulse.

+ Encoder encoder is a very important part in the structure of CNC machines. It helps measure and display numbers about the speed of the device.

+ There are two types of encoders: linear and rotary. Linear encoders respond to motion along a path, while rotary encoders respond to rotation.

2. Encoder classification

The encoder is used to manage the angular position of a rotating disc, be it the rotating disc of a wheel, motor shaft or any other device that needs to determine the angle position.
An encoder is usually classified according to its output media, including two main types: absolute encoder and relative encoder.

2.1 Absolute Encoder

Absolute Encoder: It is called absolute means that the signal we receive from the Encoder indicates the exact position of the Encoder without the user having to process anything else.

+ Use the disk in Binary or Gray code.

+ Structure includes: light emitter (LED), encoder disk (containing signal band), a light-sensitive receiver.

+ Encoder disc in Encoder is made of transparent material, people have divided the disk surface into equal angles with concentric circles.

+ Advantage: keep the absolute value when the Encoder loses power.

+ Disadvantages: high price because of complicated manufacturing, difficult to read signals.

2.2 Incremental Encoder

Incremental Encoder: Emits ascending or periodic signals

+ Material can be transparent to help light shine through.

+ As an Encoder only 1,2 or up to 3 hole rings, and often have an additional positioning hole.

+ Advantages: low cost, simple fabrication, easy handling of return signals.

+ Disadvantages: prone to error of pulse when returning. Accumulation will be accumulated during long-term operation.

3. Structure of the Encoder

The encoder includes:

+ 1 rotary disc with a hole attached to the motor shaft.

+ 1 Led light used as a light source.

+ 1 photovoltaic eye is aligned.

+ Circuit board amplifies signals.

4. Principle of operation of the Encoder

+ When the encoder is moving the adapter will process the motion and convert it into electrical signals. These signals will be transmitted to PLC control devices and processed to indicate the values to be measured by a separate program.

+ For signals with light shining or not having light passing through. It is still possible to record whether the Led is shining through this hole or not. Moreover, the number of pulses counted and increased is calculated by the number of times the light is cut off.

+ For example, on a disc there is a single hole, when each eye receives a Led signal, it means that the disk has turned 1 round.

+ Therefore, this is the basic principle of the Encoder, and for many other types of Encoders, when the disc has more holes, the signal will be different.

– How to determine the direction of motor rotation by encoder:

Usually Encoder has 2 pulse signals A and B that help us determine the direction of rotation of the motor. The Z-slot signal is a signal that is output only when the motor revolves.
To determine the direction of rotation of the motor. You see the picture below. When the LED lights on. Two phases A and B are tasked to receive signals. A and B will generate square pulses toggled in sequence. The difference in pulse frequency between A and B we can distinguish the rotation direction of the motor. See the picture on the right of phase A with a cycle before phase B.

5. Where is the Encoder application?

Encoder encoder becomes an important source for many applications. Whether it is speed, direction or distance, Encoder’s ability allows users to use this information for precise control.

Application of speed indication

Application of measurement

Application about counting quantities

Encoder application in the mechanical industry

Talking about the structure of the CNC machine, the Encoder is equipped as a device to help measure and determine the most accurate position of the machine spindle as well as the position where the cutter. Therefore when using CNC machines to process will achieve the most accurate. Moreover, through which the Encoder records will notify the PLC control system. From there, the user can adjust the cutting tool position to limit errors.

– Application in industries:

+ Car: In the automotive industry, the encoder is used as a mechanical motion sensor, which can be applied to control speed.

+ Industry: Encoder is used in labeling, packaging and is an integral part of Servo Motor.

+ Medical: The Encoder is used in medical scanners, for controlling microscopic or nano motion of automated devices and distribution pumps.

+ Army: Encoder used in positioning antenna application.

+ Scientific tools: Scientific device that implements Encoder encoder for locating observation telescope.

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