Encoder and signal processing circuit

Abstract

A reference voltage generator circuit generates a reference voltage corresponding to a power supply voltage. A current / voltage converter circuit converts a photocurrent output by a photoreceiver intovoltage, and outputs a voltage obtained by adding the converted voltage and the reference voltage. A sample and hold circuit holds a voltage of a capacitor in response to a sample and hold signal, thecapacitor having the voltage input at one end and the reference voltage input at another end. An amplifier circuit outputs an output signal where a voltage held by the sample and hold circuit is amplified with the reference voltage as a reference.

Description

[0001] Cross references to related applications [0002] This application claims priority of Japanese Application No. 2016-226888 filed on November 22, 2016, and the disclosure of this application is expressly incorporated herein by reference in its entirety. Technical field [0003] The invention relates to an encoder and a signal processing circuit. Background technique [0004] The encoder is installed in a displacement measuring device such as a dial gauge or indicator to measure the amount of displacement. A known example of such an encoder is an optical encoder that uses optical interference to measure the amount of displacement. In addition, encoders are roughly classified into incremental encoders that measure relative displacement and absolute encoders that detect absolute positions. For example, the specification of Japanese Patent No. 5,771,070 proposes a configuration for an absolute type optical encoder. [0005] In the exemplary optical encoder, illuminating light fro...

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Problems solved by technology

Therefore, there may be effects from variations in supply voltage

As described above, even in the configuration corresponding to the four-phase signal, although the output voltage for each phase can be made constant, the reference voltage REF (to which the output voltage is compared during the arithmetic operation) varies, and thus due to the arithmetic Decrease in position detection accuracy due to difference in operation timing is inevitable

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