The primary difference between linear and rotary encoders lies in the type of motion including their working principles, types, applications, and advantages.

Linear Encoders

Working Principle:
Linear encoders measure the position or displacement along a straight path. They can use various technologies, including:

• Optical: Uses light and a scale with alternating opaque and transparent sections.
• Magnetic: Employs magnets and sensors to detect position changes.
• Capacitive: Measures changes in capacitance between a sensor and a scale.

Types:

• Incremental Linear Encoders: Generate pulses as the object moves, with position determined by counting these pulses. They provide relative position but lose absolute reference if power is interrupted.
• Absolute Linear Encoders: Provide a unique position value for every point along the path, maintaining accurate position information even after power loss.

Applications:

• CNC machines for precise cutting and milling.
• Robotics for accurate movement control.
• Material handling systems to track item positions.
• Measurement devices in laboratories.

Advantages:

• High accuracy and resolution for position measurement.
• Real-time feedback for dynamic applications.
• Robustness in harsh environments, especially with magnetic or optical types.

Rotary Encoders

Working Principle:
Rotary encoders measure the angle of rotation of a shaft. They convert the rotational position into an electrical signal, which can be interpreted by control systems. The technology used can include:

• Optical: Uses a light source and sensor to detect rotational position based on a coded disc.
• Magnetic: Utilizes magnetic fields and sensors to determine the angle of rotation.
• Capacitive: Measures changes in capacitance based on the rotation of a conductive disc.

Types:

• Incremental Rotary Encoders: Generate a series of pulses as the shaft rotates. The position is determined by counting pulses, providing relative movement information.
• Absolute Rotary Encoders: Provide a unique code for each position, allowing the system to know the exact angle of rotation at any time.

Applications:

• Motor control in robotics and automation.
• Position feedback in servo systems.
• Steering angle measurement in vehicles.
• A variety of industrial machinery and equipment.

Advantages:

• High resolution and accuracy for rotational measurements.
• Immediate feedback for controlling speed and direction.
• Versatility in applications, from simple to complex systems.

Summary of Differences

In summary, linear encoders are designed for applications requiring linear measurement, while rotary encoders are suited for measuring rotational movement. Each type has its specific technologies, advantages, and applications, making them essential components in various industrial and automation systems.