POSITION DETECTION DEVICE, ROTARY SCALE, AND LIQUID DISCHARGE APPARATUS INCLUDING POSITION DETECTION DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a position detection device including a rotary scale capable of preventing false detection in a light receiving part, and to provide the rotary scale and a liquid discharge apparatus including the position detection device.

SOLUTION: The position detection device for detecting a position of a detection object 31 includes: a photosensor 60 including a light-emitting part 62 and a light receiving part 64 and including space part 613 between the light-emitting part 62 and the light receiving part 64; a rotary scale 51 overhung in the space part 613; a position detection pattern 53 which is formed on the rotary scale 51 and in which first translucent parts 53a and first light shielding parts 53b are alternately formed; and a dirt detection pattern 54 which is formed on the rotary scale 51 and in which second translucent parts 54a and second light shielding parts 54b are alternately formed and light quantity passing the pattern 54 is smaller than light quantity passing the position detection pattern 53; and a sensor position switching mechanism 70 for switching a detection state of the position detection pattern 53 and a detection state of the dirt detection pattern 54.

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