Alps Alpine's Encoders

Whereas a potentiometer converts a change in mechanical position into an analog electrical signal, an encoder converts into a digital signal. Encoders, like potentiometers, are used as both position sensors and control devices in a wide range of electrical equipment. Here we explain encoders as they are employed as control devices.

For more on encoders (magnetic encoders) used as position sensors, go here.

Types of Encoder

Encoders come in various forms. Alps Alpine supplies contact-type and magnetic rotary encoders.

Types of Encoder

Code Reading Methods

This section explains the different code reading methods by looking at the differences between the main encoder categories – incremental output and absolute output.

Incremental Output

Absolute Output

Incremental Output
Absolute Output

Whereas incremental encoders are rotated in a continuous motion, absolute encoders are used like a rotary switch to change the position of a control dial.

Encoder Series with Absolute Output

Encoder Series with Absolute Output

Basic Electrical Characteristics of Encoders

Here we explain the basic electrical characteristics of contact-type rotary encoders.


One pulse is one cycle from On to On.


The number of pulses per revolution

Phase difference:

The time lag between rises (or falls) of signal A and signal B pulses



Short, quick oscillations between On and Off at the On–Off switching position, caused by a step or burrs between conducting and insulating materials.

(sliding noise)

Momentary Off output occurring during the On state.

Sliding noise:

Slight On output occurring during the Off state.


Switching characteristics:

Threshold voltages are set to reduce the effects of the aforementioned chattering, bounce and sliding noise.

Chattering, liding noise

Types of Encoder Supplied by Alps Alpine

Besides the above incremental and absolute output signals, Alps Alpine encoders, like rotary potentiometers, have variations in shaft type and dimensions.

Types of Encoder

Structure of Alps Alpine Encoders

The following are typical encoder structures. An excellent feel can be achieved through torque and detents by optimizing flat springs and other parts.

Structure of Encoders

Alps Alpine's Magnetic Encoder

The downside of a contact-type encoder is a shorter operating life than other types.
For that reason, Alps Alpine also supplies a magnetic encoder, the EM11B Series, which achieves both a guaranteed operating life of 1 million cycles and an excellent feel.

Magnetic Encoder

For more information, visit the Product Basics section of our website.