Potential measuring device

Patent metadata

Field	Value
Publication number	US-9121875-B2
Application number	US-201313867303-A
Country	US
Kind code	B2
Filing date	Apr 22, 2013
Priority date	Apr 23, 2012
Publication date	Sep 1, 2015
Grant date	Sep 1, 2015

Abstract

There is provided a potential measuring device of non-contact type which can improve measurement sensitivity. A potential measuring device which measures a charged object in a non-contact manner with a sensor includes: a first shutter and a second shutter each having a shutter part provided with an opening and a leaf spring part; a magnet attached to the leaf spring part of each of the first shutter and the second shutter; a yoke on which a coil is disposed, the coil applying an alternating magnetic field to the magnet of each of the first shutter and the second shutter to cause the shutter part to reciprocate via the leaf spring part; and a natural frequency adjusting means for adjusting a natural frequency of at least one of a first shutter system including the first shutter and the magnet and a second shutter system including the second shutter and the magnet.

First claim

What is claimed is:

1. A potential measuring device which measures a surface potential of a charged object in a non-contact manner with a sensor disposed to oppose the charged object, the device comprising:
a first shutter and a second shutter each having a shutter part, which is disposed between the charged object and the sensor and has an opening, and a leaf spring part extending from the shutter parts;
a magnet attached to the leaf spring part of each of the first shutter and the second shutter;
a yoke on which a coil is disposed, the coil applying an alternating magnetic field to the magnet of each of the first shutter and the second shutter to cause the shutter part to reciprocate via the leaf spring part; and
a natural frequency adjusting means for adjusting a natural frequency of at least one of a first shutter system comprising the first shutter and the magnet attached to the first shutter and a second shutter system comprising the second shutter and the magnet attached to the second shutter.

2. The potential measuring device according to claim 1 , wherein
the natural frequency adjusting means comprises an adjusting back yoke disposed on an opposite side of a side of the leaf spring part that opposes the yoke and adjusting a magnetic force between the adjusting back yoke and the magnet, and a support means for supporting the adjusting back yoke.

3. The potential measuring device according to claim 2 , wherein
the natural frequency adjusting means changes a distance between the magnet and the adjusting back yoke.

4. The potential measuring device according to claim 2 , wherein
the natural frequency adjusting means changes an opposing area between the magnet and the adjusting back yoke.

5. The potential measuring device according to claim 2 , wherein
a thread part is formed in an outer periphery of the adjusting back yoke and a screw hole is formed in the support means, a magnetic force between the adjusting back yoke and the magnet is adjusted by adjusting a degree of screwing the thread part of the adjusting back yoke into the screw hole, and by this adjustment of magnetic force the natural frequency of at least one of the first shutter system and the second shutter system is adjusted.

6. The potential measuring device according to claim 2 , wherein:
the support means is provided with a pivot member which is pivotable about a fulcrum, the adjusting back yoke is provided on a portion of the pivot member, which is far from the fulcrum; and
the adjusting back yoke is provided to be capable of being positioned between a position where the adjusting back yoke opposes the magnet and a position where the adjusting back yoke does not oppose the magnet by pivoting the pivot member.

7. The potential measuring device according to claim 1 , wherein:
the shutter part of the first shutter and the shutter part of the second shutter are disposed to oppose each other in a direction linking the charged object and the sensor; and
in the opposing disposition, by moving the respective shutter parts of the first shutter and the second shutter by operation of the coil, the shutter parts are capable of being positioned between an open state in which an opening area which is an overlap between the respective openings along an orthogonal direction becomes large and a closed state in which the opening area becomes smaller than in the opening state.

8. A potential measuring device which measures a surface potential of a charged object in a non-contact manner with a sensor disposed to oppose the charged object, the device comprising:
a first shutter and a second shutter each having a shutter part, which is disposed between the charged object and the sensor and has an opening, and a leaf spring part extending from both ends of each of the two shutter parts;
a magnet attached to the leaf spring part of each of the first shutter and the second shutter;
a yoke on which a coil is disposed, the coil applying an alternating magnetic field to the magnet of each of the first shutter and the second shutter to cause the shutter part to reciprocate via the leaf spring part;
an adjusting back yoke disposed on an opposite side of a side of the leaf spring part that opposes the yoke and adjusting a magnetic force between the adjusting back yoke and the magnet; and
a magnetic force adjusting means for adjusting a magnetic force between the adjusting back yoke and the magnet.

Assignees

• Koganei Ltd

Inventors

• Fukada Yoshinari
• Meguro Fumihito

Classifications

• G01R29/12 Primary

  Measuring electrostatic fields {or voltage-potential} · CPC title

• G01R19/00

  Arrangements for measuring currents or voltages or for indicating presence or sign thereof (G01R5/00 takes precedence; for measuring bioelectric currents or voltages A61B5/24) · CPC title