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Proceedings Paper

Utilization of a digital method to determine the rotation direction in incremental photoelectric encoder
Author(s): Yousheng Li
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Paper Abstract

The principles of incremental photoelectric encoders are: When a encoder disk rotates, (1)it will produce the pulse signal proportional to the angle; (2) it will also produce the sensing signal of identifying the rotation direction. The way that the existing incremental photoelectric encoders determine the rotation direction is: one encoder disk has 3 code channels: 'A', 'B' and 'Z'. On both 'A' and 'B' code channels, there are a number of evenly distributed grid holes, and they have the same cycle, but with one quarter cycle difference in phase between channel 'A' and 'B'. When disk rotates clockwise, signal phase from 'A' channel is a quarter cycle ahead of that from 'B'; Similarly, when disk rotates counterclockwise, 'B' signal phase will be a quarter cycle ahead of 'A'. Based on the above phenomena, a circuit can identify the rotation direction, which is known as 'Kam-Phase Method'. The mechanism of the new direction recognition method is: When the encoder disk rotates , it continuously generates three kinds of state binary information sequentially. These three states are defined as state 1, state 2, state 3. While rotating clockwise, the state changes in the order of state 1, state 2, state 3, state 1.....; While rotating counterclockwise, the state changes in the sequence of state 1, state 3, state 2, state 1..... The new theory differentiate the digitized state changing sequence between the clockwise and counter clockwise to determine the rotation direction.This method is called as 'Digital Method'. The advantages of applying the digital method for the rotation direction determination in incremental photoelectric encoder are: the code channel structure is simpler and there is no accumulative errors and so on.

Paper Details

Date Published: 12 October 2010
PDF: 8 pages
Proc. SPIE 7659, 5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Smart Structures and Materials in Manufacturing and Testing, 765917 (12 October 2010); doi: 10.1117/12.866312
Show Author Affiliations
Yousheng Li, Jiangxi Blue Sky Univ. (China)


Published in SPIE Proceedings Vol. 7659:
5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Smart Structures and Materials in Manufacturing and Testing
Xiangang Luo; Georg von Freymann, Editor(s)

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