Optical encoder with changeable comparator hysteresis and operating method thereof
AssigneePixart Imaging Inc.
InventorsChung-Min Thor, Kuan-Choong Shim
Life of this patent
Estimating the term…
Abstract
There is provided an optical encoder including a phase shifter circuit and a multiple hysteresis comparators. The phase shifter circuit receives four input signals, and outputs multiple phase shifted signals based on the four input signals. Each of the multiple hysteresis comparators uses a changeable operation hysteresis level to compare a couple of phase shifted signals among the multiple phase shifted signals, wherein the changeable operation hysteresis level is determined corresponding to a signal frequency of the four input signals.
Claims17
An optical encoder, comprising:
- a phase shifter circuit, configured to receive a first input signal, a second input signal, a third input signal and a fourth input signal, and output multiple phase shifted signals based on the first input signal, the second input signal, the third input signal and the fourth input signal;
- a comparison circuit, comprising multiple hysteresis comparators each being configured to compare a couple of phase shifted signals among the multiple phase shifted signals using an operation hysteresis level;
- and
- a frequency detector, configured to detect a signal frequency according to at least one of the first input signal, the second input signal, the third input signal and the fourth input signal, and select the operation hysteresis level of each of the multiple hysteresis comparators according to the detected signal frequency.
An operating method of an optical encoder, the optical encoder comprising multiple hysteresis comparators and a frequency detector, the operating method comprising:
- comparing, by each of the multiple hysteresis comparators, a couple of phase shifted signals among multiple phase shifted signals using a first operation hysteresis group;
- detecting, by the frequency detector, an input signal frequency;
- and
- changing, by the frequency detector, the first operation hysteresis group to a second operation hysteresis group when the detected input signal frequency exceeds a frequency threshold.
An optical encoder, comprising:
- a phase shifter circuit, configured to receive four input signals, and output multiple phase shifted signals based on the four input signals;
- and
- multiple hysteresis comparators, each being configured to use a changeable operation hysteresis level to compare a couple of phase shifted signals among the multiple phase shifted signals, wherein the changeable operation hysteresis level is determined corresponding to a signal frequency of the four input signals.
Dependencies are inferred from the claim text.