Electricity: measuring and testing – Magnetic – Displacement
Reexamination Certificate
1999-10-29
2001-08-21
Strecker, Gerard R. (Department: 2862)
Electricity: measuring and testing
Magnetic
Displacement
C324S226000, C324S229000, C324S231000, C271S265040
Reexamination Certificate
active
06278270
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to devices that can detect small changes in distance between opposed surfaces and methods of detecting small distance changes between opposed surfaces using the devices.
2. Description of Related Art
Imaging devices include, for example, electrophotographic and electro graphic printers, ink jet printers and thermal printers. In these devices, an imaging substrate is fed into a feed path and conveyed through the apparatus to an imaging station for imaging. Multiple imaging substrates, such as paper sheets, are typically stored in stacks in the imaging apparatus. The substrates are separated from each other so that individual substrates are fed into the feed path for imaging.
SUMMARY OF THE INVENTION
A problem that commonly occurs in imaging devices is multifeeds, i.e., multiple substrates that overlie each other being fed into the feed path simultaneously. Multifeeds are caused by adjacent sheets becoming attached. For example, stacks of paper sheets are formed by cutting. When the sheets are cut by a cutting element, edges of adjacent sheets can become attached to each other. If the sheets are not properly separated from each by a separating device of the imaging devices, then two or more sheets can be fed into the feed path as a multifeed. Multifeeds are also caused by electrostatic attraction between adjacent sheets caused by pressure or friction.
Multifeeds can cause various problems in imaging devices. Imaging devices can image sheets on either one side or on two opposed sides. Imaging devices can include single and tandem print engines for forming one and two-sided images, respectively. When multifeeds occur, sheets can pass through the apparatus without being imaged. In tandem print engine apparatus, when multifeeds occur, it is not possible to print on both opposed sides of a sheet and, thus, two-sided prints can not be formed. In addition, multifeeds can cause jams in the feed paths, requiring imaging to be stopped until the jam can be cleared.
Multifeeds can also occur in apparatus in which indicia, such as labels, are placed on substrates.
This invention provides devices that can sense small changes in the distance between opposed surfaces.
This invention separately provides apparatus that include the devices. The devices can be retrofitted in the apparatus or can be original components of the apparatus.
This invention separately provides apparatus that comprise paths for feeding substrates and devices according to this invention for sensing multifeeds of the substrates along the paths.
This invention separately provides apparatus comprising devices according to this invention to sense wear and/or contamination of component surfaces that contact substrates.
This invention separately provides apparatus that comprise devices according to this invention to sense that improperly sized substrates, such as those having an improper thickness and/or length, have been loaded into the apparatus. The substrates can have various different compositions and can be opaque or light transparent.
This invention also provides methods for sensing small changes in the distance between opposed surfaces.
This invention separately provides methods for sensing multifeeds in apparatus.
This invention separately provides methods for sensing wear or contamination of components in apparatus.
This invention separately provides methods for determining if improper substrates have been loaded into an apparatus.
In various exemplary embodiments, the devices that sense small changes in the distance between opposed surfaces according to this invention comprise a first surface, a second surface that is movable relative to the first surface, a ferromagnetic material (permanent magnet) operatively associated with the first surface or the second surface, and a giant magneto resistance (GMR) effect sensor operatively associated with the first surface or the second surface. Under an applied current, the sensor changes it's internal magnetic field coupling and resistivity according to changes in magnitude of the external field that impinges on the sensor from the ferromagnetic material. The magnitude of the external field F between the first and second surfaces is determined by the magnetic properties of the ferromagnetic material; it is also a function of the distance d between the ferromagnetic material's center and a position of interest or location of the sensor. The device senses changes in the distance between the first and second surfaces caused by these surfaces moving relatively toward or away from each other. The changes in the sensor's internal magnetic field and resistivity can be correlated to the change in distance between the first and second surfaces.
The devices according to this invention can be utilized in various applications in which small distance changes between opposed surfaces indicate a change in some condition or that a problem has occurred. The devices are particularly advantageous for use in an imaging apparatus. The devices can be placed in the feed paths of the imaging apparatus to detect substrate feeding problems, including multifeeds and the feeding of improperly sized substrates. The devices can also be used in imaging apparatus for other purposes, such as to detect wear and/or contamination of surfaces.
In various exemplary embodiments, methods of this invention comprise applying a current to a giant magneto resistance effect sensor in the presence of an external magnetic field to cause the sensor to change it's internal magnetic field coupling and resistivity according to changes in magnitude of the external field that impinges on the sensor from the ferromagnetic material when a first surface moves relatively toward or away from a second surface, such as, for example, when an object passes between the first and second surfaces. The changes in the sensor's internal magnetic field and resistivity are correlated to changes in the distance between the first and second surfaces, which in turn can be correlated to a dimension of the object.
These and other features and advantages of this invention are described in or are apparent from the following detailed description of various exemplary embodiments of the systems and methods according to this invention.
REFERENCES:
patent: 4692700 (1987-09-01), Nix
patent: 4767987 (1988-08-01), Montgomery
patent: 5293118 (1994-03-01), Grossmann et al.
patent: 5373235 (1994-12-01), Clark, Jr. et al.
patent: 5647583 (1997-07-01), Emigh et al.
patent: 5662324 (1997-09-01), Cannaverde et al.
patent: 5744950 (1998-04-01), Seefeldt
patent: 5929631 (1999-07-01), Striker et al.
patent: 6060969 (2000-05-01), Hufgard et al.
patent: A-2-187602 (1990-07-01), None
patent: A-5-301657 (1993-11-01), None
Gutberlet Douglas A.
Hall Carl H.
Myers James B.
Robles-Flores Eliud
Ryon Randall C.
Oliff & Berridg,e PLC
Strecker Gerard R.
Xerox Corporation
LandOfFree
Apparatus and method for detecting small distance changes... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method for detecting small distance changes..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method for detecting small distance changes... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2546081