Browse Prior Art Database

ESV SENSE ACTIVATION MOVER (SHUTTER FUNCTION)

IP.com Disclosure Number: IPCOM000025282D
Original Publication Date: 1984-Jun-30
Included in the Prior Art Database: 2004-Apr-04
Document File: 4 page(s) / 183K

Publishing Venue

Xerox Disclosure Journal

Abstract

An electromagnetically activated device to move an electrode for an ESV (electrostatic voltmeter or electrometer for non-contact measurement of elestro-static voltages) and its associated circuitry from a zero (standby) to a sense (measure) position. The device provides that all moving parts (including the solenoid armature) are supported by pivots or bearings. Problems with con-tamination and wear of sliding parts are minimized. Also, the "pulled in" position is determined by magnetic force so there is no mechanical hard stop with its associated shock and vibration. In addition, the electrode can partially move down into (rather than simply move to behind) the window and thus spacing from electrode to sensed surface can be minimized. Finally, the moving electrode assembly can, at least partially, seal the window opening while in the zero and sense positions thus reducing entry of dirt into the ESV head.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 49% of the total text.

Page 1 of 4

KEROX DISCLOSURE JOURNAL

Proposed Classification
U.S. c1. 355/3

Int. Cl. G03g 15/00

FlG. l

Volume 9 Number 3 May/June 1984 191

[This page contains 1 picture or other non-text object]

Page 2 of 4

ESV SENSE ACTIVATION MOVER (SHUTTER FUNCTION) (Cont'd)

An electromagnetically activated device to move an electrode for an ESV (electrostatic voltmeter or electrometer for non-contact measurement of elestro- static voltages) and its associated circuitry from a zero (standby) to a sense (measure) position. The device provides that all moving parts (including the solenoid armature) are supported by pivots or bearings. Problems with con- tamination and wear of sliding parts are minimized. Also, the "pulled in" position is determined by magnetic force so there is no mechanical hard stop with its associated shock and vibration. In addition, the electrode can partially move down into (rather than simply move to behind) the window and thus spacing from electrode to sensed surface can be minimized. Finally, the moving electrode assembly can, at least partially, seal the window opening while in the zero and sense positions thus reducing entry of dirt into the ESV head.

One of the problems with a conventional solenoid actuated shutter for an ESV is that the solenoid armature pulls in to a relatively hard stop. This comes from the usual desire to move a solenoid load to a specific position. However, there is usually not a specific position for the shutter to be open, only that the shutter be clear of the space between the electrode and the photoreceptor (or surface with the unknown voltage). The shutter can also be closed relatively slowly.

These objectives may be achieved without having the solenoid bang into a hard stop for the shutter open system. This may be accomplished by using a solenoid where the armature pulls in to the position where it (the armature) is magnetically centered with respect to the solenoid. This is not a precisely defined position, but all that matters is that with minimum armature travel, the shutter will be open. The shock, mechanical shock in this case, often found with opening a shutter with a conventional solenoid will be virtually eliminated. A relatively weak spring can be used to close the shutter. A mild, and probably variable, shock will occur at shutter closed position. This mechanical shock is not a functional concern; but it must be minimized in order to obtain reasonable life and reliability.

The approach to sense activation (shutter function) for a low cost ESV is to move the sense electrode and its associated circuitry (up through a pre Amp) into and away from a window in the ESV case. One design approach to this would use a small PWB or hybrid circuit which would be slid into and out of the sense position using a linear solenoid and return spring, but this would cause sliding friction and the possibility of dirt contamination of sliding surfaces.

It is, therefore, worthwhile to look at some apparently more co...