公开(公告)号：US20180156640A1

公开(公告)日：2018-06-07

申请号：US15820525

申请日：2017-11-22

Applicant: MITUTOYO CORPORATION

Inventor： Hirokazu KOBAYASHI ,  Osamu KAWATOKO

IPC: G01D5/347 ,  H02J7/00 ,  H05B33/08

CPC classification number: G01D5/34715 ,  H02J7/0063 ,  H05B33/0842 ,  H05B37/0281

Abstract: An encoder includes a light source. A booster circuit boosts a power supply voltage output by a battery, and outputs the boosted voltage. The voltage is applied to one end of a light-emitting diode. A driver circuit is inserted between another end of the light-emitting diode and a ground, the driver circuit controlling current flowing through the light-emitting diode. A voltage detector circuit detects a voltage between the light-emitting diode and the driver circuit. A control circuit causes the booster circuit to boost the power supply voltage when the voltage is lower than the power supply voltage; stops the boosting performed by the booster circuit when the voltage is equal to the power supply voltage; and controls the driver circuit such that, after the voltage reaches a predetermined value, current flows to the light-emitting diode.

公开(公告)号：US20180143040A1

公开(公告)日：2018-05-24

申请号：US15804170

申请日：2017-11-06

Applicant: MITUTOYO CORPORATION

Inventor： Osamu KAWATOKO ,  Tomohiro TAHARA ,  Hirokazu KOBAYASHI

IPC: G01D5/347 ,  G11C27/02

CPC classification number: G01D5/34707 ,  G01D5/24428 ,  G01D5/34715 ,  G01D5/34746 ,  G01D5/38 ,  G11C27/026

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 into voltage, 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, the capacitor 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.