|Publication number||USRE39689 E1|
|Application number||US 09/982,327|
|Publication date||Jun 12, 2007|
|Filing date||Feb 21, 2002|
|Priority date||Aug 22, 1996|
|Also published as||CN1092800C, CN1183569A, DE69717362D1, DE69717362T2, EP0825757A2, EP0825757A3, EP0825757B1, US5736738, US5998786|
|Publication number||09982327, 982327, US RE39689 E1, US RE39689E1, US-E1-RE39689, USRE39689 E1, USRE39689E1|
|Inventors||Abdolreza Movaghar, Josephine del Rosario, Mark Diel, David J. Schmeling|
|Original Assignee||Hewlett-Packard Development Company, L.P.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (5), Classifications (11), Legal Events (5)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This is a continuation of application Ser. No. 08/701,619, filed Aug. 22, 1996 now U.S. Pat. No. 5,736,738.
This invention relates to the field of optical systems, and more particularly to optical systems employing optical sensors which require alignment for proper operation of the system.
Optical systems such as optical scanner devices for scanning a recorded image to produce a representative image use optical sensor arrays such as charged coupled device (CCD) arrays. The CCD array is situated relative to the recorded image such that the recorded image and CCD array move relative to each other, wherein the recorded image moves in relation to the optical sensor array. The sensor array converts the image into electrical signals representative of image pixels comprising the image. Typical of these optical scanner devices are multiple function machines which include the functions of a printer, facsimile machine, photocopy machine and/or optical scanner device within one machine.
In order to achieve optimal scanning quality, the optical sensor and the optical system need to be aligned, positioned and fixed in space relative to each other. For a single line CCD, five degrees of freedom (DOF) out of six DOF are essential to this alignment. The majority of scanners on the market today have active control of only four DOF; movement along the x and z axis and rotation about the y axis are controlled on the CCD device, and movement along the y axis is controlled on the lens. Consequently these scanners have very small tolerances in the rotational z direction. The typical securing method is to tighten down two screws which hold the CCD relative to the optical path. This tightening process imparts torques and forces to the CCD which move it from the optimum aligned position. Also, moving the lens in the y direction degrades the optimum alignment because (i) the optical axis is typically not parallel to the axis of movement, and (ii) mechanical imperfections in the lens and/or housing cause undesired movement in the other axes during movement in the y direction.
It would therefore be an improvement in the art to provide an optical sensor system with improved alignment capabilities, wherein the optical sensor can be aligned without causing forces moving the sensor from the optimum aligned position.
In accordance with an aspect of the invention, apparatus is described for securing an optical apparatus at a fixed relative location within a range of motion. The apparatus includes a first housing member holding the optical apparatus, and a first bracket member fabricated of a UV transparent material. The apparatus further includes a compliant apparatus for holding the first housing member and the first bracket member loosely together, while permitting relative motion between the first housing and the first bracket member through a range of motion. A curable bonding element applied between areas of the first housing member and the first bracket member bonds the first housing member and the first bracket member together in a fixed position within the range of movement. The bonding element is applied while in a liquid state to permit the relative motion, and includes an adhesive which is cured to a solid state by exposure to ultraviolet light. The first housing member and the first bracket member are fixed in the relative position by the curing of the adhesive to a solid state.
A preferred application for the invention is in an optical scanner device, wherein the optical sensor array is moveable through a range of motion relative to a scanner housing, and then fixed in a desired location within the range of motion by use of the curable element.
These and other features and advantages of the present invention will become more apparent from the following detailed description of an exemplary embodiment thereof, as illustrated in the accompanying drawings, in which:
The scanning station 30 includes a scanner assembly 50 which includes a light source for illuminating the surface of the document 10 to be optically scanned, the light reflected from the document surface through a light path indicated by line 52 which is folded by mirrors 52, 54 and 56 and directed through a lens 58 for focusing onto a linear optical sensor array 60, attached to a printed circuit assembly board 62. In this exemplary embodiment, the sensor array 60 comprises a linear charge coupled device (CCD) array. As is known in the optical scanner art, the document 10 is sequentially advanced through the scanner station in incremental steps, with the array 60 capturing thin lines or areas of the document surface in electrical signal form, e.g. as a line of pixels having pixel values. The device includes a processor (not shown) for assembling the successive lines of pixels into an image of the scanned document surface.
To optimize the scanning performance of the optical scanner station 30, the sensor array 60 is typically optically aligned with respect to the image projected through the lens 58, and then secured in place. This invention concerns a technique by which the sensor array is fixed in position within a range of movement.
The optical apparatus in accordance with this invention provides active control over five DOF during the securing process. All five DOF (x, y, z, and rotational z and y) are controlled on the CCD array 60 without any movement of the lens 58. The lens can be secured prior to alignment and fixing in position of the CCD array, and is preferably not moved during the CCD array alignment and subsequent securing process. Securing of the CCD array is done through a gimbal design in a CCD housing and middle bracket which creates the five DOF required. There are no screws involved in the securing process to impart torques or forces to the parts. An ultraviolet (UV) activated adhesive is used to secure the CCD housing to the middle bracket and the middle bracket to the optical scanner housing. The middle bracket is clear, and a high percentage of the UV light can pass through it to cure the adhesive applied between the two parts. A vertical hole runs through tabs of both the CCD housing and the middle bracket. The adhesive is applied into this region where it is constrained by the parts. The adhesive is a liquid during the alignment process which allows relative motion between the parts. When the parts have been moved to the proper position within the range of motion, the adhesive region is exposed to UV light which cures the adhesive into a solid vertical column, creating a form of chemical rivet. This chemical rivet provides a very strong mechanical interlock of the components in addition to the adhesive bonding of the components.
The CCD printed assembly board 62 is secured to a CCD housing 80 by threaded fasteners 64A and 64B which are received in bores 82A and 82B. In this exemplary embodiment, the CCD housing is fabricated of an opaque rigid plastic material, e.g. a polycarbonate modified with 20% glass fibers, and is formed to define a generally rectilinear interior enclosed area 84 which receives the CCD array 60 and forms an opaque structure around the structure 60. The housing 80 has a window opening 86 formed in wall 86A through which image light passes from the lens 58 to the CCD array 60. Thus, the position of the CCD array 60 is rigidly fixed in relation to the CCD housing 80. The housing 80 further includes protruding tabs which extend generally along a center axis of the elongated housing 80, and have formed therein openings 90A and 90B which receive UV-cured adhesive, as will be described in further detail. The tabs further have protruding ears 92A and 92B.
The scanner assembly 50 further includes a middle bracket 100 which is fabricated of a material which is substantially transparent to UV light. An exemplary material suitable for the purpose is a clear plastic material such as polycarbonate. One exemplary commercially available polycarbonate is LEXAN (TM), 3412-739, marketed by General Electric Company. The bracket 100 includes several features, including attachment clip elements 102A and 102B for loosely affixing the bracket 100 to the scanner housing 70. The scanner housing 70 includes a flat wall 72 which defines a generally planar surface 74 against which a corresponding generally planar surface 104 abuts. The wall has an opening 76 (
The middle bracket 100 further includes a window 112 defined through the wall 114 which aligns with the window 86 formed in the CCD housing to permit image light to pass therethrough from the lens to the window 86.
The middle bracket 100 further includes a compliance apparatus for holding the middle bracket and the CCD housing member 80 loosely together while permitting relative motion between these two elements within a range of motion. The compliance apparatus includes four flexible, curved fingers 106A-106D which are integrally formed with the bracket. The fingers 106A-106B have respective ends integrally attached to a post section 108 defined in the wall 104 and which extends generally transversely to the elongate axis 114 of the middle bracket. Similarly the fingers 106C and 106D have respective ends integrally attached to a post section 110 defined in the wall 104 and extending generally transversely to the elongate axis 114. The tip of each finger curves inwardly away from the wall 104. The finger tips each contact the outward surface of the wall 86A of the CCD housing when the housing and bracket 100 are brought together. Since the fingers are formed in the curved position illustrated in
The compliance apparatus of the middle bracket further includes pairs of spaced, aligned tabs 116A-116B and 116C-116D which extend transversely from the wall 104. The spacing between the tabs of each pair is sufficient allow the tabs 88A and 88B of the CCD housing 80 to slide therebetween when the housing 80 and bracket are assembled together, e.g. as shown in FIG. 2. To lock the bracket 100 and housing 80 in a loosely assembled configuration, the bracket 100 further includes lugs 118A and 118B extending outboard of the tabs 116A-116D, with barb ends 120A, 120B sliding over the respective ears 92A and 92B of the housing 80. While the lugs 118A and 118B lock the elements 80 and 100 together in the loosely assembled configuration, relative movement between the elements 80 and 100 through a range of movement is not constrained by the locking action of the lugs. The range of movement includes rotational movement about the Z axis (
The pairs of tabs 116A-116B and 116C-116D have formed therethrough aligned hole pairs 130A-30B and 130C-130D, which receive liquid adhesive, as will be described in further detail. It is to be noted that the diameter of the holes 130A-130D is smaller than the diameter of the holes 90A-90B formed in the CCD housing 80. The holes 130A and 130C are through holes, extending through the respective tabs 116A and 116C. The holes 130B and 130D extend only partially into the respective tabs 116B and 116D, as shown in
When the bracket 100 is affixed to the scanner housing 70 by the clips 102A, 102B, the features 104A, 104B are adjacent adhesive-receiving features 78A, 78B formed in the wall 74 of the scanner housing 70. The features 78A, 78B are, in this exemplary embodiment, T-shaped depressions formed in the wall 74. With the middle bracket 100 clipped against the wall 74, the corresponding features 78A, 140A and 78B, 140B form cavities with an open channel defined by the notches 144A, 144B leading from the top edge 104A into the cavities. Adhesive in a liquid state can be dispensed into these cavities through the channels. The interior surfaces of the cavities can be roughened to provide improved surface adhesion.
Two other adhesive-receiving cavities are employed in the scanner assembly 50 in accordance with the invention, in order to rigidly fix the relative positions of the middle bracket 100 and the CCD housing 80. These two cavities 152A and 152B, (cavity 152B is shown in FIG. 7), with application and curing of adhesive in the cavities, provide the means of rigidly fixing the relative positions of the elements 80 and 100 at one position within the range of movement permitted by the compliance apparatus. The adhesive can be dispensed in its liquid state into the cavities 152A, 152B with the assembly in an upright position as shown in FIG. 7.
The adhesive dispensed into the cavities 150A, 150B and 152A, 152B is, in this exemplary embodiment, an adhesive which is a liquid when in an uncured state, and is cured by application of ultraviolet (UV) light to a solid state. Thus, the parts 70, 80 and 100 will be assembled loosely together by use of the clips 102A, 102B, and the locking lugs 118A, 118B to a rest position. The adhesive in its liquid, uncured state is dispensed into the cavities 150A, 150B, 152A, 152B. The CCD board 80 can then be moved within the range of movement permitted by the compliance apparatus, and the bracket 100 can be moved within the range of movement permitted by the clips 102A, 102B, until a desired position of the CCD board and the middle bracket is reached. Preferably this position is one at which the array 60 is aligned with the image light from the lens 58, but this invention permits the elements 70, 80 and 100 to be locked in any position within the range of movement, without the use of threaded fasteners. With the elements 70, 80 and 100 held in the desired position, e.g. in a fixture, the assembly is illuminated with UV light. Because the middle bracket 100 is fabricated of a material which is transparent to UV light, the adhesive in the cavities will be exposed to the UV light and cured to a solid state. The parts are then fixed at the desired position.
Adhesives suitable for this purpose are commercially available. One such adhesive is available from the Loctit Corporation, as adhesive 3321, part no. 19739. The adhesive can be cured to a solid state with an exposure time in the range of tens of seconds.
It is understood that the above-described embodiments are merely illustrative of the possible specific embodiments which may represent principles of the present invention. Other arrangements may readily be devised in accordance with these principles by those skilled in the art without departing from the scope and spirit of the invention.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US5367399||Feb 13, 1992||Nov 22, 1994||Holotek Ltd.||Rotationally symmetric dual reflection optical beam scanner and system using same|
|US5391009||Oct 29, 1993||Feb 21, 1995||Hewlett-Packard Company||Single motor actuation for automatic stack feeder system in a hardcopy device|
|US5463212||May 7, 1993||Oct 31, 1995||Hitachi Maxell, Ltd.||Latent image forming member and method of manufacturing, latent image reading apparatus and latent image reading system|
|US5477047||Oct 21, 1993||Dec 19, 1995||Matsushita Electric Industrial Co., Ltd.||Direct-contact type image sensor device, an image sensor unit, and methods for producing the same|
|US5736738||Aug 22, 1996||Apr 7, 1998||Hewlett-Packard Company||Apparatus for securing CCD board at a fixed position within a range of motion|
|U.S. Classification||250/239, 250/504.00R, 250/234|
|International Classification||H04N1/03, H04N1/028, H04N1/19, E06B7/28, A47G29/02|
|Cooperative Classification||H04N1/03, H04N2201/02429|
|Sep 30, 2003||AS||Assignment|
Owner name: HEWLETT-PACKARD DEVELOPMENT COMPANY L.P., TEXAS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:HEWLETT-PACKARD COMPANY;REEL/FRAME:014061/0492
Effective date: 20030926
Owner name: HEWLETT-PACKARD DEVELOPMENT COMPANY L.P.,TEXAS
Effective date: 20030926
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:HEWLETT-PACKARD COMPANY;REEL/FRAME:014061/0492
Effective date: 20030926
|Jun 20, 2007||REMI||Maintenance fee reminder mailed|
|Jul 10, 2007||FPAY||Fee payment|
Year of fee payment: 8
|Jul 10, 2007||SULP||Surcharge for late payment|
Year of fee payment: 7
|Jun 7, 2011||FPAY||Fee payment|
Year of fee payment: 12