What is an encoder?
Encoder literally means encryption. It is generally called a device that converts a mechanical motion (linear and rotational) into an electrical signal so that different characteristics can be obtained from that signal used.

Encoders are a special type of sensor that receives position information and relays this information to other equipment. Encoders are used to detect position, velocity, and direction of rotation of the motor shaft and other moving mechanical equipment. They provide the information needed for precise speed control in applications such as rotary table positioning, pick and place, machine assembly, packaging, robotics, and more.
 

Application of encoder
Encoders are usually installed in automation and control systems in a part that can send feedback from the output to the controller and specify the following parameters:

Speed ​​measurement
Position measurement and control
To rotate the shaft

Types of encoders

Encoder in terms of construction

Linear encoders

Rotary or rotary encoders
Encoder in terms of performance and interior construction (production technology)

Optical

Magnetic

capacitive

Encoder in terms of signal output type

Absolute

Additive

Optical encoders

Optical encoders are the most accurate type of encoders. When selecting an optical encoder. It is important that the encoder has additional protection to prevent contamination from dust, vibration and other common industrial conditions.

Magnetic encoders

Magnetic encoders, although more resistant than optical encoders and are often used in environments exposed to pollution, steam, vibration and other types of environmental interference, but the resolution or accuracy of optical encoders is higher.

Capacitive encoders

Capacitive encoders are newer than the previous two models in the world of industry. Capacitive encoders are as strong as magnetic models, but optical encoders have a higher resolution than capacitive encoders. Of course, capacitive encoders, regardless of the type of technology used, have the ability to detect motion and convert it into standard signals common in the industry.

Linear encoders

Linear encoders are used to measure linear motion and are structurally produced in optical, magnetic and capacitive types. The optical model linear encoder has digital output and the magnetic and resistive linear encoder has analog output. These encoders are used in devices such as presses to measure the longitudinal movement of the piston jack and in rollers to measure the longitudinal distance between the roller balls.

Incremental rotary encoders

Incremental encoders mean that we have pulses and signals at the output while the encoder is moving, and the number of these pulses must be counted in the controller to measure speed and position, but if the controller is reset (power is cut off and Turn on again) forget the previous position of the encoder and again have to count the pulse of the encoder to get new information. One of the disadvantages of incremental encoders is that you can not understand the previous and real position of the encoder, which makes this model of encoders cheap.

Magnetic rotary encoders

Rotary encoders are similar to incremental encoders, but Hall effect sensors are used to generate pulses.

Incremental encoder

If the encoder has only one pulse row, it can not show the direction of rotation correctly and must have a second pulse. For this purpose, another transmitter and light receiver must be added to the set. There is a need for a third pulse, which is generated by a complete rotation cycle, which is called the command pulse, and it is also used to count the number of turns.

Absolute encoder

One of the drawbacks of incremental encoders is that the pulse count is stored in an external counter. If the power goes out or there is a discrepancy anyway, the counting will be lost. Because the zero point for restart is underestimated or not defined, this means that if we take power from an electric car with an encoder that has an electric rotator, the other encoder He will not know the correct position. Absolute encoders are used to solve this problem. In this case, the car always knows its position. In an absolute disk encoder that has such a group of parts in a concentric circular shape is used the starting point of concentric circles in the center of the rotating encoder disk is used. The previous and inner ring will have a turquoise. The first ring, which is the innermost ring, will have a clear shape and a dark part, and the third ring will have 4 parts from each of the parts. If the encoder has 10 rings, the last ring or the farthest from the center 512 Is a piece. If each loop of the absolute encoder has twice as many pieces as the previous loop, a binary system is established between the numbers. In this type of encoder, there is a light source for each loop on the disk and receive it.

Application of encoder in industry
Speed ​​measurement
Position measurement

Angle measurement

Measure the direction of shaft movement

Cnc machines

Industrial robots

Packing machines

Elevator

How to choose an encoder

What points should be considered to choose an encoder?

Degree of protection or the same ip54, ip60, ip65 and ip67

Ability to adjust the pulse rate from 90 to 180 degrees

Tolerance of livestock suffering for operation in different environments from -40 ° to 100 °

Accuracy at high rotational speed (rpm)

European and American standards such as (ul, vde, CE and CSA)

Vibration Proof or electric shocks in the environment