Rotary Encoders measure the number of rotations, the rotational angle, and the rotational position. Linear Encoders are also available to measure linear movement.

What Are Rotary Encoders?

Rotary Encoders are sensors that detect position and speed by converting rotational mechanical displacements into electrical signals and processing those signals. Sensors that detect mechanical displacement for straight lines are referred to as Linear Encoders.

Features of Rotary Encoders

(1) The output is controlled according to the rotational displacement of the shaft.
Linking to the shaft using a coupling enables direct detection of rotational displacement.

(2) Returning to the origin is not required at startup for Absolute Encoders.
With an Absolute Encoder, the rotational angle is output in parallel as an Absolute value.

(3) The rotation direction can also be detected.
The rotation direction is determined by the output timing of phases A and B with an Incremental Encoder, and by the code increase or decrease with an Absolute Encoder.

(4) Choose the optimal Sensor from a wide lineup of resolutions and output types.
Select the Sensor to match the requirements for precision, cost, and connected circuits.

Operating Principles

Selection Guidelines

1. Incremental Encoder or Absolute Encoder?
 

Select a type that is suitable in terms of the cost vs. capacity, returning (or not) to the origin at startup, the maximum speed, and noise tolerance.

2. How much resolution is needed?
 

Select the optimal model in view of required precision and cost of machine equipment. We recommend selecting a resolution of from 1/2 to 1/4 of the precision of the machine with which the Encoder will be used.

3. Dimensions

Also take into consideration the type of shaft that is required (hollow shaft or regular shaft) in relation to mounting space.
 

4. Permitted Shaft Loading
 

When selecting, take into consideration how the mounting method affects the load on the shaft and mechanical life.

5. Maximum Permissible Speed
 

Base your selection on the maximum mechanical speed during use.

6. Maximum Response Frequency
 

Base your selection on the maximum shaft speed when the device in which the Encoder is used is in operation.

Maximum response frequency = (Revolutions (RPM) /60) × Resolution.
There are deviations in the actual signal periods, so the specifications of the selected model should provide a certain amount of leeway with respect to the above calculated value.
 

7. Degree of Protection
 

Select the model based on how much dust, water, and oil there is in the application environment.

Dust only: IP50
Water or oil also present: IP52(f), IP64(f) (water-resistant, oil-resistant)
Oil present: Oil-proof construction
 

8. Startup Torque of Shaft
 

How much torque does the drive have?
 

9. Output Circuit Type
 

Select the circuit type based on the device to be connected, the frequency of the signal, transmission distance, and noise environment.
For long distance transmission, a line-driver output is recommended.
 

Interpreting Engineering Data

Bearing Life

Example model: E6B2-C

• This graph shows the relationship between mechanical life and the load applied to the shaft.

• The size of the load during rotation affects the life of the bearings.

Cable Extension Characteristics

Example model: E6B2-CWZ6C

Measurement Example:
Power supply voltage: 5 VDC
Load resistance: 1 kΩ (Output residual voltage is measured at a 35 mA load current.)
Cable: Special Cable

• This graph shows the effect of the output waveform if the cable is extended.

• Extending the cable length not only changes the startup time, but also increases the output residual voltage.