The Difference between Incremental Encoder and Absolute Encoder
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The rotary encoder is an angle sensor that outputs the rotation displacement information of the rotator as a digital signal.
There are two types of encoders: Incremental type and Absolute Type.
Incremental Encoder
Incremental type, there are three phases outputs of A-phase, B-phase, and Z-phase, and the A-phase and the B-phase create the output pulses that accompany rotation like “H(High)→L(Low)→H→L→”. It is possible to discriminate the direction of rotation of the phase difference between the A and B phases and the number of pulse counting enables for the calculation of the rotation amount.
That is to say, this is a method of counting the relative movement amount from a certain position, and to defined the position “0” which is the starting point of the count, the Z-phase is used which outputs once per each rotation.
The incremental type has the following advantages/ disadvantages.
(Advantages)
- Low cost compared to the absolute type.
- The simple signal processing composed of the rotation direction discrimination and the counters.
- Easy to handle as it is compatible with another different maker’s incremental encoder.
(Disadvantages)
- When starting up the equipment, one must always perform the zero return action of the encoder.
- If the succeeding equipment miscounts due to noise or the like, the count value can not be corrected AND the positional data will remain incorrect.
Absolute Encoder
Absolute type outputs the absolute position of the rotation angle. Therefore, the reset action task was not required at the machine startup and the angular position can quickly be detected automatically. Also, even if the shaft of the absolute encoder has rotated during the time that the equipment was turned off, the angular position is detected correctly when the power is turned on again.
The absolute type has the following advantages / disadvantages.
(Advantages)
- Because of the detection of the absolute position of the rotation angle, the machine can be started immediately without any reset actions as needed with the incremental type.
- Even if there are measurement errors that occur as caused by things such as outer noise, angle reading error does not accumulate because of the detection of the absolute position and therefore the reliable angle position can be detected.
(Disadvantages)
- Because of its complicated structure in comparison to the incremental encoder, the price of the absolute encoder is higher than that of an incremental encoder.
MIDORI Encoder
At Midori, we do the development and commercialization of the magnetic encoder by using a magnetic sensor technology that has been cultivated over the years from the development of Blue Pot (MR position sensor) and Orange Pot (Hall effect position sensor).
And then consequently, the magnetic absolute encoder CE36M series had launched in 2018 (and incremental type will be came out the middle of next year.)
Midori’s magnetic absolute encoder has the following features:
- Feasible to be used even in bad environments such as vibration, dust, dew condensation and oil mist which would be hard for the optical type to be used.
- Enough resolution to be used: 13 to 17 bits.
- Stable detection and high reliability due to high noise resistance and surge resistance.
- Abundant output format.
① ASI (Asynchronous Serial Transmission): This is a format for easy interfacing with the PC.
② SSI (Synchronous Serial Transmission): This is a standard format that is simple and conforming to the receiving unit of some PLCs.
③ SPI (Serial Peripheral Interface): This is a format that is widely used in microcomputer peripherals and is suitable for taking positional data with a microcomputer or the like.
Midori Encoders
Absolute Magnetic Rotary Encoder CE36M |
If you want to design your own magnetic encoder…
Multi-Pole Magnet Scale |
If you have any inquires, opinions, or requests that you would like to make, please contact us.
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