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Types of Encoders: The Complete Guide

About Types of Encoders, Precision control is crucial in applications that require motors. When you have precision control problems in your circuits, the first thing that comes to mind is a stepper motor.

However, not all situations require such extreme measures. So, If you need precise control for smaller projects like a rotary motor shaft, you’re reading the right article.

An easy solution to these problems is an encoder motor.

Encoders are cheaper and simpler solutions for precision control problems. But, it might be hard to understand how it works.

Luckily, we wrote this article to show you how an encoder works, types, and the various applications.

Are you ready? Let’s dive in!

What is an Encoder Motor

If you’re in a situation where a stepper motor is inefficient and costly – the encoder motor is what you need.

Unlike the stepper motor, the encoder motor features a rotary encoder at its backside that sends feedback signals to the system. 

How? Well, it uses the rotary encoder to track the position and speed of the motor shaft.

Here’s the best part.

There is a wide variety of encoder motors on the market. Some of these motors are absolute or incremental, while others are magnetic or optical. 

In other words, the type of encoder largely depends on the size, shape, and application type.

Encoder Diagram

Source: Wikimedia Commons

How Does an Encoder Work

There are two outputs in any rotary encoder with labels A and B. Sometimes, these two outputs perform similar functions, which is creating signals. These signals can be magnetic, optical, and resistive. The most common is the optical encoder which gives signals based on the interruption of light.

Here’s an instance to make things easier to understand. Depending on the manufacturer, we can think of rotary encoders like stitches inside the encoder made with GND or Vcc (Voltage common collector). When a rotational movement in the encoder, the common terminal touches either the A terminal or the B terminal.

If the encoder rotates clockwise, contact A will go high first, followed by contact B. In other words, there will always be a 90-degree phase shift regardless of the direction of rotation (counterclockwise or clockwise).

Dual Binary Encoders

Source: Wikimedia Commons

Plus, you can easily detect this phase shift by using a microcontroller. It helps you determine the rotary direction. Once you do this, you can increase or decrease a counter that shows you the RPM or the degree of rotation if you have a geared encoder motor.

Types of Motor Encoders

As mentioned earlier, there are various encoder types with different features, shapes, and sizes. However, here are the main types of encoder motors you can find on the market.

AC Motors Encoders

DC motors are not the only motors with encoders. AC motors with encoders are also available on the market. An AC induction is a common choice for control systems and generic applications. Why? Because such applications have a long life and low cost. You can find these types of motors in lathe machines that require speed control.

Another application of AC motor encoders is in robotics. The encoder provides information on the position and path of the robot’s movement, at all times, during the application.

Stepper Motor Encoders

We know what you’re thinking. Why would a stepper motor work with an encoder? After all, precise control is what the stepper motor does best. 

But, this is not the case. 

While the stepper motor is good at precise control, the encoder still has a large impact on the performance of the stepper motor. Thus, a stepper motor encoder is a stepper motor integrated with an encoder.

We call stepper motor systems with encoder integrations closed-loop stepper motors. These motors offer more stability, smoothness and achieve higher torques than their open-loop counterparts.

A stepper motor encoder provides closed-loop feedback control. Also, it avoids the step loss caused by the stepper motor. Additionally, we can divide the stepper motor encoder into optical encoders and rotary encoders.

DC Motor Encoders

These are the most common types of encoder motors you can find on the market. Usually, it is a generic DC motor with a magnetic encoder strapped to its backside. At the front, there might be a gear assembly that decreases the RPM and increases the torque.

Also, the encoder gives closed-loop feedback to the system that allows you to adjust the rotations per minute and drive for precise speed control.

In other words, you can control the speed of the feedback in DC motors. It is possible because the DC motor encoder offers a mechanism that allows you to measure the speed of the rotor. 

Servo Motor Encoders

The application of the servo motor has become a popular alternative to hydraulic, pneumatic, and a few other electromechanical forms of motion. 

Additionally, you can use servo motors with encoders for various applications, including factory automation, robotics, and other precision control operations.

Servo motor encoders offer high torque technology, small size, and high efficiency at a reasonable price. Also, it is the go-to for production facilities around the world.

Types of Encoder Technology

Here are different kinds of rotary encoders you can choose from – depending on your application.

Linear Encoders

Linear encoders are common in industrial automation and control applications. This device uses a linear scale to determine its position. 

Linear Encoders 

Linear Encoders 

Source: Flickr

On this scale, there is a sensor that reads the scale and determines the position. Furthermore, a digital vernier caliper is a perfect example of a linear encoder. 

You can find linear encoders in instruments with high precision, like industrial automation tools. 

Also, you may consider linear encoders as absolute or incremental.

Optical Encoders

The optical encoder is the most widely used encoder on this list. Its components are a light source, a light detector circuit, and encoder disks.

It is a motion-sensing device that uses light from a code disk to monitor the movement of a shaft. In other words, this encoder gives feedback based on light interruption.

Optical encoders

Optical encoders

Source: Wikimedia commons

Here’s how it works:

First, powering up the device turns on the light source. The light source then emits a beam of light that passes through a transparent encoder disk with patterns and opaque lines. 

Next, the photodetector picks up the light beam and responds to it. So, this process produces a sinusoidal waveform that transforms into a pulse train or square wave. We call the photodetector the light detector circuit.

The pulse signal is light = on and no light = off. These signals then transfer to the counter through the electronics board. Finally, the counter sends the signal and produces the proper functions (rotate, stop, etc.).

Incremental Encoders

This type of encoder converts the position of a shaft or the angular motion into a digital or analog code. It uses this code to pick out motion or position. Also, it is one of the most commonly used rotary encoders.

You can also use an incremental encoder in motor speed and positioning feedback applications. Such applications include heavy-duty, servo/ light, and industrial applications.

Additionally, incremental encoders provide great speed and distance feedback. Also, it doesn’t need multiple sensors, so the systems are simple and less expensive. 

The only limit of the incremental encoder is providing change information. For this, the encoder needs to calculate motion with a reference device.

Incremental encoders

Incremental encoders

Absolute Encoder

The absolute encoder is the most interesting encoder on this list. It measures true or absolute angular position. It is the opposite of the incremental encoder that only calculates the change in angular position.

Here’s where things get interesting.

The power-up determines if the encoder is absolute or incremental. Thus, if the encoder goes through a ‘wake and shakes’ process to get its position, then it’s incremental. If it doesn’t require motion to output its position, then it’s absolute.

Absolute encoders can deliver a digital signal or analog signal as their output. These signals include a serial synchronous interface (SSI) and 0-10v or 4-20mA. 

Angular Encoders

Angular Encoders

Source: Flickr

Applications of Encoders

Here are some of the various applications of encoders:

Aerospace

Encoders provide high-precision motion feedback in aerospace applications when operating in terrible environmental conditions.

Aerospace 

Aerospace 

Ball Screw Positioning

Encoders provide motion feedback when attached to the end of the drive motor or drive shift.

Ball screw positioning

Automated Vehicles & Robots

Encoders provide precise motion feedback for applications in automated robotics.

Automated robots

Cut – To – Length

Here, the encoder generates a fixed amount of pulses. These pulses transfer to the controller and determine the travel length.

Rounding up

Picking the perfect encoder for your product design is crucial. This is why it is necessary to understand the differences between the four types of encoder technology and encoder motors. 

Encoder Configuration

Encoder Configuration

Source: Wikimedia Commons

With the technologies changing, ensure you select the encoder that fits your position feedback requirements. 

Well, that concludes everything you need to know about encoders, types, and different applications. If you need more information about the encoder, feel free to reach us, and we’ll be happy to help.

Hommer Zhao
Hi, I am Hommer, the founder of WellPCB. So far, we have more than 4,000 customers worldwide. If you have any questions, you can feel free to contact me. I really appreciate any help you can provide.

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