Surface potential sensor and copying machine

Patent metadata

Field	Value
Publication number	US-10073127-B2
Application number	US-201214354451-A
Country	US
Kind code	B2
Filing date	Mar 14, 2012
Priority date	Nov 15, 2011
Publication date	Sep 11, 2018
Grant date	Sep 11, 2018

Abstract

This surface potential sensor is provided with an electret electrode ( 28 ), which is configured of a metal film ( 26 ) and an electret film ( 27 ), said electret electrode being provided on an upper surface of a diaphragm ( 25 ) of a semiconductor substrate. Four piezoresistors ( 29 a, 29 b, 29 c, 29 d ) are formed on the diaphragm ( 25 ), and a distortion quantity detecting unit ( 32 ) is configured by forming a bridge circuit using the piezoresistors. Since an electrostatic force that operates between an object and the electret electrode ( 28 ) changes corresponding to potential of the object, and the electret electrode ( 28 ) warps corresponding to the change, the potential of the object can be detected by measuring a distortion quantity of the electret electrode ( 28 ) by means of the distortion quantity detecting unit ( 32 ). Consequently, not only the potential of the object but also a polarity thereof can be detected with reduced size and high sensitivity.

First claim

The invention claimed is:

1. A surface potential sensor, comprising:
a thin-film electret electrode with flexibility, wherein the rear surface of the thin-film electret electrode is supported by an elastic material; and
an electrostatic force detector configured to detect a change in electrostatic force that operates on the thin-film electret electrode, wherein
the electrostatic force detector comprises:
a deformable member which deforms in response to deformation of the thin-film electret electrode; and
a distortion quantity detecting device configured to detect a distortion quantity of the deformable member,
wherein the deformable member and the distortion quantity detecting device are embedded in the elastic material without being exposed.

2. The surface potential sensor according to claim 1 , wherein an electret film is formed on the surface of a metal film in the thin-film electret electrode.

3. The surface potential sensor according to claim 1 , wherein
an outer peripheral portion of the thin-film electret electrode is supported by a support, and
an inner region thereof is floating in a space.

4. A copying machine, comprising:
the surface potential sensor according to claim 1 .

5. The copying machine according to claim 4 , wherein the surface potential sensor is arranged as opposed to the outer peripheral surface of a photosensitive drum.

6. The copying machine according to claim 5 , wherein the surface potential sensor is configured to be capable of travelling along a width direction of the photosensitive drum.

Assignees

• Matsushita Soichi
• Omron Tateisi Electronics Co

Inventors

• Matsushita Soichi

Classifications

• G01R29/0814

  Field measurements related to measuring influence on or from apparatus, components or humans (EMC, EMI and similar testing in general G01R31/001), e.g. in ESD, EMI, EMC, EMP testing, measuring radiation leakage; detecting presence of micro- or radiowave emitters; dosimetry; testing shielding; measurements related to lightning · CPC title

• G01R15/165

  measuring electrostatic potential, e.g. with electrostatic voltmeters or electrometers, when the design of the sensor is essential (electrometers with passively moving electrodes G01R5/28; measuring electrostatic fields G01R29/12; measuring charge G01R29/24; measuring in circuits with high internal resistance G01R19/0023) · CPC title

• G01R29/0842

  Measurements related to lightning, e.g. measuring electric disturbances, warning systems · CPC title

• G01R31/2642

  Testing semiconductor operation lifetime or reliability, e.g. by accelerated life tests · CPC title

• G01R19/0023

  Measuring currents or voltages from sources with high internal resistance by means of measuring circuits with high input impedance, e.g. OP-amplifiers (electrostatic instruments G01R5/28; measuring electrostatic potential G01R15/165; measuring electrostatic fields G01R29/12; amplifiers per se H03F) · CPC title