Types and Applications of Servo Motor Encoders-2
Classification：
Knowledge
Release Time：
2026-04-21
II. Classification by Measurement Method
1. Incremental Encoder
Working Principle: Generates a specific number of pulses for each unit of rotation. It has no inherent memory of absolute position; it only reports changes in position. The standard output is a pair of quadrature pulse signals (Phase A and Phase B), which are 90 degrees out of phase.
- Position: Determined by counting the total number of pulses from a reference point.
- Direction: Determined by the phase sequence (A leading B or B leading A).
- Speed: Calculated by measuring the pulse frequency.
- Index Pulse (Z-phase): A single pulse per revolution used to establish a reference or 'home' position.
- Simple Structure & Low Cost: Straightforward design and signal processing.
- High-Speed Capability: Excellent performance at very high rotational speeds.
- Flexible Counting: The controller can use pulse multiplication (e.g., 4x quadrature counting) to effectively increase resolution.
- Loses Position on Power Loss: Requires a 'homing' or 'reference' move upon power-up to establish a zero position.
- Cumulative Error: Potential for counting errors due to electrical noise or missed pulses over long travels.
2. Absolute Encoder
Working Principle: Each unique shaft position corresponds to a unique, specific digital code (binary, Gray code, etc.). It directly outputs the absolute angular position at any moment, without relying on pulse counting or a reference point. The coded disc has multiple concentric tracks, with each track representing a bit in the digital word.
- Power-off Memory: Retains position information when powered down; no homing required.
- High Reliability: No cumulative error; position is determined directly, not by counting.
- Instant Position: Provides immediate valid position upon power-on.
- High Safety: Ideal for safety-critical applications where knowing position at all times is essential.
- Higher Complexity & Cost: More complex electronics and disc design, leading to higher cost.
- Resolution Limits: While very high, ultra-high resolutions can be prohibitively expensive.
3. Hybrid Encoder
Comprehensive Comparison of Encoder Types
| Feature | Photoelectric Encoder | Magnetic Encoder | Inductive Encoder (Resolver) | Incremental Encoder | Absolute Encoder |
|---|---|---|---|---|---|
Precision | Highest | Medium | Low-Medium | High (Relative) | High (Absolute) |
Resolution | Very High | Medium-High | Low | High (via counting) | Very High |
Environmental Resistance | Poor (Needs Clean Environment) | Excellent | Outstanding | Medium | Medium-Poor |
Shock/Vibration Resistance | Low | High | Very High | Medium | Medium |
Power-off Position Memory | No | No | Yes (1 revolution) | No | Yes |
Cost | High | Medium | Medium-High | Low | High |
Typical Application | Precision Instruments | General Automation | Heavy Industry | Conveyors | Robots, CNC |
Conclusion: Selecting the Right Encoder
- Prioritize Photoelectric Encoders when ultra-high precision and resolution are paramount in a clean, stable environment.
- Choose Magnetic Encoders for cost-effective, robust performance in dirty, vibrating, or space-constrained applications.
- Opt for Resolvers when uncompromising durability in the harshest conditions is the top priority.
- Use Incremental Encoders for cost-sensitive, high-speed applications where homing is feasible.
- Specify Absolute Encoders for safety-critical, complex, or multi-axis systems where position integrity and power-off memory are essential.
Key words：
The previous one：
Quick Navigation
Focus on the research and development of encoders and sensor-related products.
Give us an email to surprise you
Contact Us
