In manufacturing sites and industrial equipment, precise motor control and speed management are essential elements that determine product quality. Crucial to achieving this is a position sensor called encoders.
Encoders measure rotational angles or linear displacement with high precision and output this data as electrical signals, enabling precise control of motors and actuators.
This article explains the basic mechanism, types, and selection criteria of encoders from an engineer's perspective, providing information useful for your equipment development and product improvement. Development engineers seeking to achieve high-precision position control should read on.
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ENCODERS FUNDAMENTALS AND ROLE: THE IMPORTANCE OF POSITION DETECTION IN MOTOR CONTROL
Encoders are sensors that detect a machine's rotational angle or displacement distance, converting it into digital or pulse signals for output. When combined with a motor, they accurately determine rotation direction, rotational speed, and current position, enabling feedback control.
Widely adopted in applications requiring precise positioning, such as industrial robots, machine tools, and medical equipment, encoders form a foundational technology supporting product performance and reliability.
Topics covered in this section
- What are encoders: Sensors that "Visualize" Rotation and Movement
- The Role of Encoders in Motor Control
- Primary Applications and Industrial Use Cases
This section explains everything from the basic concept of encoders to their specific role in motor control and examples of their use in industrial fields.
| WHAT ARE ENCODERS: SENSORS THAT "VISUALIZE" ROTATION AND MOVEMENT |
An encoder is a measuring device that converts physical rotational or linear motion into electrical signals. Mounted on a motor shaft, it detects in real time how much rotation has occurred and in which direction movement is taking place. The detected information is sent to the control unit as pulse signals or digital signals, enabling precise positioning to target locations and operation at constant speeds.
The operating principle of encoders involves reading patterns of light or magnetism that change with rotation or movement, converting these changes into electrical signals. For example, in an optical encoder, a sensor reads slit patterns engraved on a disk, outputting changes in light intensity as pulse signals. The control device calculates the amount of movement by counting the number of pulses and determines the direction of movement based on the sequence of pulse generation.
It functions as the "eye" of the machine, conveying the motion state to the control system, much like humans use vision to judge distance and speed. Without encoders, it is impossible to accurately determine the motor's current position or how much it has moved, making precise control difficult.
| THE ROLE OF ENCODERS IN MOTOR CONTROL |
Since a motor alone cannot self-recognize its rotation amount or position, feedback signals from the encoders are essential. The control unit reads the pulse signal output by the encoder, detects deviations from the target value, and adjusts the motor drive accordingly.
This closed-loop control enables high-precision positioning, speed control, and torque control, leading to improved product quality and enhanced production efficiency. Particularly in medical equipment and precision equipment, where micron-level positioning accuracy is required, encoders' performance directly impacts product reliability.
| PRIMARY APPLICATIONS AND INDUSTRIAL USE CASES |
Encoders are adopted across a wide range of industrial sectors and are utilized in applications such as the following.
[Primary Applications by Sector]
- Arm control for Industrial robot
- Tool positioning in CNC machine tools
- Stage movement in semiconductor manufacturing equipment
- Lens drive for medical endoscopes
- Electronic lock control for security equipment
- Autofocus mechanisms for optical equipment
Compact encoders combined with Coreless motors are particularly valued in medical equipment and precision instruments where miniaturization and high precision are essential. In these fields, achieving both device miniaturization and control accuracy is a key challenge, making encoder selection a critical factor determining product performance.
ENCODERS MECHANISMS AND MAIN TYPES - DETECTION METHODS AND CHARACTERISTICS BY TYPE
Encoders are primarily classified by detection method into optical and magnetic types, and by measurement target into rotary encoder and linear encoder. They are further distinguished by signal output method into incremental and absolute types, each possessing distinct characteristics and application domains.
Contents covered in this section
- Classification by Detection Method: Optical and Magnetic
- Rotary encoder and linear encoder
- Differences Between Incremental and Absolute Types
This section explains the operating principles and features of each type, providing fundamental knowledge for selection based on application requirements.
| CLASSIFICATION BY DETECTION METHOD: OPTICAL AND MAGNETIC |
Optical encoder detects rotation using a slit disc and a light sensor, characterized by high resolution and high precision. They combine LEDs or photodiodes to convert the light pattern passing through the disc's slits into a pulse signal.
Magnetic encoders utilize magnets and Hall elements, offering excellent environmental resistance, making them suitable for environments with high levels of dust or vibration. Optical encoders tend to be chosen for medical and precision equipment requiring miniaturization and precise control, while magnetic encoders are preferred in harsh industrial environments.
| ROTARY ENCODER AND LINEAR ENCODER |
Rotary encoders measure the rotational angle of a motor shaft, while linear encoders measure the position of a linearly moving object. Rotary encoders feature a disc-shaped detection element directly mounted on the motor shaft, outputting the rotation amount as a pulse signal. They are widely used in industrial motors, servo motors, and stepper motors.
Linear encoders are adopted for machine tool table feed and stage control in semiconductor manufacturing equipment, enabling high-precision measurement of linear displacement. Selecting the appropriate type for the application contributes to improved control performance.
| DIFFERENCES BETWEEN INCREMENTAL AND ABSOLUTE TYPES |
Incremental type and absolute type differ significantly in their position information output methods.
| Item | Incremental type | Absolute type |
| Position Information | Relative Movement Amount | Absolute Position |
| When power is off | Loses position information | Retains position information |
| Return to origin | Required | Not required |
| Cost | Low cost | High cost |
| Primary Applications | Speed control, simple positioning | Precision positioning, multi-axis control |
The incremental type outputs relative displacement as pulse signals. It is simple and low-cost, but it loses position information when power is turned off.
Absolute types continuously output absolute position, eliminating the need for origin return after power-up and reducing system startup time. Selecting the appropriate type depends on application requirements and control system specifications.
KEY POINTS FOR ENCODER SELECTION AND SOLUTIONS FOR ACHIEVING HIGH-PRECISION CONTROL
Encoder selection requires evaluating multiple technical specifications, including resolution, response speed, mounting method, and environmental resistance. For motor encoders specifically, compatibility with motor characteristics significantly impacts control performance.
Topics covered in this section
- Resolution and Accuracy: How to Determine Performance Based on Application
- Motor Compatibility: Mounting Methods and Electrical Matching
- I. Takiron Corporation Solutions for Achieving High-Precision Control
This section outlines key selection criteria and introduces encoder solutions that deliver compact size, high precision, and long service life.
| RESOLUTION AND ACCURACY: HOW TO DETERMINE PERFORMANCE BASED ON APPLICATION |
Resolution (PPR) indicates how many pulses an encoder can output per revolution, measured in PPR (Pulses Per Revolution). While this varies significantly by application and manufacturer, higher values enable finer position detection and improve control accuracy.
Medical and optical equipment may require tens of thousands of PPR or more. However, higher resolution increases cost and size, necessitating selection that balances required control precision with overall system constraints. Excessive resolution increases control circuit load and susceptibility to noise, demanding a perspective focused on identifying the optimal specification for the application.
| MOTOR COMPATIBILITY: MOUNTING METHOD AND ELECTRICAL MATCHING |
When mounting encoders on a motor shaft, both physical compatibility and electrical matching must be verified.
| Check Items | Key Checkpoints |
| Shaft Diameter | Compatibility between motor shaft diameter and encoders mounting holes |
| Mounting Space | Dimension constraints at the rear of the motor |
| Coupling Method | Flexible, rigid, direct drive, etc. |
| Output Signal Format | Voltage Level (5V/12V/24V systems) |
| Signal Method | Differential Output/Single-Ended |
| Interface | Communication Protocol with Control Unit |
Compact motors benefit from space-saving encoder designs, and mechanical mounting accuracy also impacts control performance. To prevent misdetection due to shaft misalignment or vibration, proper coupling selection and secure mounting are essential.
| TACHIRON CI'S SOLUTIONS FOR ACHIEVING HIGH-PRECISION CONTROL |
C.I. Takiron Corporation offers control solutions combining compact, high-precision coreless motors with encoders. Coreless motors, featuring cogging-free and smooth rotational characteristics, deliver outstanding performance when paired with encoder position feedback in applications demanding advanced control, such as medical equipment, precision instruments, and industrial robots.
Our Micromotors offer high reliability through domestic design and quality control, along with strong customization capabilities tailored to specific applications. We maintain a product lineup optimized for entire systems, including models with gearheads, and provide technical consultation from the development stage. For product details or technical inquiries, please feel free to contact us via the inquiry form.
SUMMARY
Encoders are essential sensors for motor control in many applications requiring high-precision positioning. Various types exist based on detection methods and signal output types.
Selecting the appropriate encoder selection for the application enables improved product performance and ensures reliability. Especially in fields demanding compact size and high precision, solutions combining Coreless motors with encoders are highly effective.
C.I. Takiron Corporation supports your equipment development with high-quality Micromotors products and technical support.
Product Information & Inquiries
For detailed information on C.I. Takiron Corporation's Micromotors products, please visit the website below.
- Product Site: https://cik-ele.com/en/
- Coreless motors: https://cik-ele.com/en/products/list/coreless-motors-en/
- Brushless motors: https://cik-ele.com/en/products/list/brushless_motors-en/
- Geared motors: https://cik-ele.com/en/products/list/gearheads-en/
- Encoder: https://cik-ele.com/en/products/list/encoders-en/
If you are having trouble selecting a small motor for your product development, please feel free to consult us via the inquiry form. Our technical staff will discuss your application and requirements and propose the optimal solution.
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