Hi, it’s Morio.
Already October. Time flies.

This time, I will explain the components and electrical elements that make up an encoder.

1. Disk or Code Wheel
Function:
The disk or code wheel forms the core of the encoder, providing reference marks for optically reading physical movements (rotation or linear motion)

Operation:
In rotary encoders, the disk is attached to the motor shaft and transmits its rotation to the encoder. In linear encoders, the code wheel moves and tracks this movement. Each time the marks (usually slits or holes) on the disk or code wheel pass in front of the light sensor, light is blocked or passed through, and this is converted into an electrical signal.

Material:
Disks are typically made of glass, plastic, or metal. Glass disks offer high transparency and allow for precise measurements but are fragile. Plastic offers good impact resistance and low cost but less durability. Metal provides the greatest durability and is suitable for industrial environments.

Shape:
Disks usually have finely spaced slits or holes. These slits or holes act as a basic mechanism for the sensor to read the position by allowing or blocking light. The shape is typically circular, with slits radiating from the center.

2. Light Source (LED or Laser)
Function:
The light source is used within the encoder to illuminate the marks on the disk or code wheel, allowing the light sensor to detect their presence and position.

Operation:
Light emitted from the source is blocked or passed by the marks on the disk or code wheel, and the light sensor detects this to generate signals for measuring the position and speed of the marks.

Material:
LEDs are made from semiconductor materials (usually gallium arsenide), and lasers are made from semiconductors or doped glass.

Shape:
LEDs are small and compact chips, while lasers are often housed in cylindrical or box-shaped casings.

Electrical Characteristics:
LEDs operate at low voltage (typically 1.8V to 3.3V) and consume current in the range of a few milliamperes to tens of milliamperes. They are long-lasting and energy-efficient. Lasers, offering high coherence and directionality, can produce focused beams for more precise measurements and generally require higher voltages and more current than LEDs.

3. Light Sensor
Function:
The light sensor detects changes in the light as it is blocked or allowed to pass by the marks on the disk or code wheel.

Operation:
The light sensor captures the timing of light being blocked or passing and converts this into an electrical signal. This signal is processed by subsequent electronic circuits and analyzed as data related to the machine’s position, speed, and direction.

Material:
Light sensors are made from semiconductor materials such as phototransistors and photodiodes.

Shape:
They are generally housed in small flat or cylindrical packages, with a small window positioned to receive the light.

Electrical Characteristics:
Light sensors are photoelectric converters that operate by applying a reverse bias voltage, producing a photocurrent. This current is then amplified and processed by downstream electronic circuits.

4. Electronics (Signal Processor)
Function:
The signal processor converts the analog signals received from the light sensor into digital signals and further processes these signals to a usable format.

Operation:
This component amplifies, filters, and converts digital signals, improving signal quality and minimizing reading errors, thus providing more accurate and reliable data to the control system.

Material:
Components such as microprocessors and amplifiers are made from silicon chips and other semiconductor materials.

Shape:
These components are typically mounted on a PCB (printed circuit board) and are square or other regular shapes.

Electrical Characteristics:
Signal processors often include analog-to-digital converters (ADCs) which require high precision in terms of sampling rates and bit resolution. Filtering circuits may also be included to remove noise and shape the signals, typically involving operational amplifiers or transistors.

5. Bearings or Guides
＜Bearing＞
Function:
Primarily used to support rotating parts and minimize friction, ensuring smooth operation and long-term durability.

Operation:
Positioned around the rotating shafts in rotary encoders, bearings effectively reduce friction during rotation, ensuring stable rotation which is fundamental for accurate data reading by the encoder. Bearings also prevent shaft misalignment and enhance rotational smoothness, minimizing reading errors.

Materials:
Bearings are made from high-carbon steel, chrome steel, or ceramics. Guides can be made from metals (steel or aluminum), plastics, or composite materials.

Shape:
Bearings include inner and outer rings with spherical or cylindrical rolling elements. Guides are typically long bars or rails, either straight or curved, to maintain the path of moving parts.

<Guide>
Function:
Used in linear encoders to support the movement of parts in a straight line, maintaining mechanical stability.

Operation (Guides):
Guides accurately guide moving parts such as the code wheel or sensor components. In linear motion, guides reduce friction while ensuring parts maintain a precise linear path, protecting against external shocks or vibrations which could affect reading accuracy.

Material:
Guides can be made from metals (such as steel or aluminum), plastics, or composite materials.

Shape:
They are typically long bars or rails, either straight or curved, forming the structural pathway for the moving parts.

These encoder components and their materials, shapes, and electrical characteristics significantly influence the performance and applicability of encoders, especially in industrial applications where environmental resilience is crucial for precise positioning and speed control.

6. Power Supply
Function:
The power supply provides the necessary electrical power to all electronic components within the encoder.

Operation:
A stable power supply directly impacts the performance and reliability of the encoder, hence it is designed to minimize noise and maintain a consistent output. This ensures that the encoder operates accurately.

Electrical Characteristics:
The power requirements of an encoder vary depending on the type of light source or sensors used, but typically a stable DC power supply is needed. The quality of the power supply is crucial as power noise can affect the encoder’s accuracy. Regulators and filtering circuits may be required to suppress ripples and spikes.

7. Connection Interfaces
Function:
Connection interfaces provide the means to transmit data from the encoder to the main control system.

Operation:
The interface provides digital or analog outputs depending on the signal format, transferring data in a compatible manner. This allows information from the encoder to be effectively utilized across the system.

Electrical Characteristics:
Encoder outputs are available in various forms such as digital (TTL or HTL), analog, and fieldbus (for example, CAN bus or Profibus). In digital interfaces, the output typically forms logic levels through pull-up or pull-down resistors. In the case of analog, changes in voltage or current directly correspond to the readings.