Abstract:
A document-guiding device that clips onto the image sensor of a document scanner ensures that documents to be scanned are introduced into the scanner at an optimal angle and are applied to the transparent surface of the image sensor at an optimal pressure, thereby avoiding scratching and soiling the sensor glass surface. Moreover, the deep input guide clip includes a sharp edge that acts as a scrapper to remove or flatten protruding impurities to further reduce soiling the sensor transparent surface. The deep input guide clip has the added benefit of stopping parasitic ambient light and protecting the image sensor against hard falling objects thus avoiding breakage of the transparent surface. The deep input guide clip forms a compact enclosure that may also hold a set of document proximity sensors and associated control electronics for precisely detecting the leading edge of the document when it is introduced in the scanner, its width and its trailing edge.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention pertains to the field of document scanner computer peripherals. In particular, the present invention is drawn to precision deep input guide clips that guide the document over the image sensor at an optimal angle and at an optimal pressure, and to document scanners using the same. 
     2. Description of the Related Art 
     Document scanners are computer peripherals that allow users to scan documents into their computers for later storage, retrieval and/or manipulation. Although document scanners are extremely useful peripherals, they have not yet attained the ubiquity of other common peripherals, such as CD-ROM or DVD drives, printers, modems or multimedia sound cards, for example. This state of affairs persists despite the fact that prices for document scanners for personal computers are low and continue to decline rapidly. It does not appear, therefore, that price constitutes a significant barrier to entry for consumers seeking to upgrade the functionality of their personal computers and for manufacturers seeking to integrate scanners into their own products. Instead, it is believed that document scanners have not, to date, realized their anticipated success due to a combination of shortcomings including lack of integration, poor reliability, difficulty of use and slow speed. 
     Several types of scanners exist, each type being specifically designed for a particular purpose: monochrome, color, sheet-fed, flatbed, handheld, photo-print, photo-slide, SCSI host interface, printer port host interface, IEEE1284 parallel port host interface, serial port host interface, USB host interface, IEEE1394 FireWire host interface, etc. Development costs and time to market are therefore significant. Only scanner manufacturers that are fully committed to document scanner products can afford to be involved in document scanner developments. Manufacturers that wish to incorporate document scanner functions into other types of equipment (multifunction terminals, consumer appliances, gaming devices for example) in order to differentiate their products from those of the competition have experienced difficulties in meeting their goal. 
     FIG. 1 shows a typical arrangement for a sheet-fed document scanner. In FIG. 1, a document  1  is displaced by a rotating roller paper feeding mechanism  3  driven by a motor  4  over a fixed image sensor  2  that senses reflected light from the document  1 . Alternatively, the paper feeding mechanism may be a belt, a plurality of rollers or a combination of one or more rollers and belts. Illumination is provided from the image sensor  2 . The image sensor  2 , together with its associated electronics (not shown), records a line of information at a time. When the document  1  is driven by the motor  4  and the roller  3 , the image sensor  2  records the entire document area swept. The scanner control electronics and the communication link with the host computer are not shown, for clarity. 
     FIG. 2 shows a typical arrangement for a duplex document scanner. In FIG. 2, a document  1  is displaced by two rotating rollers  3  and  6  driven by a motor  4  over two fixed image sensors  2  and  5  that sense reflected light from each side of the document. Alternatively, the paper feeding mechanism may be a plurality of belts (one shown at reference numeral  7  in FIG.  2 ), or a plurality of rollers and belts. Illumination is provided from each image sensor  2 ,  5 . The image sensors  2 ,  5 , together with their associated electronics (not shown), record a line of information for each side of the document  1 . When the document  1  is driven by the motor  4  and the rollers  3 ,  6 , the image sensors  2 ,  5 , together with their associated electronics, record the entire area swept of the document  1  on both sides thereof. The scanner control electronics and the communication link with the host computer are not shown in FIG.  2 . 
     The image sensors used in sheet-fed and duplex scanners, for example, may be charge-coupled devices (CCD), monochrome or color sensors having a width of approximately 40 to 60 mm fitted with a suitable optical apparatus to reduce the image of the document and an illumination source or monochrome or color contact image sensors (CIS). These image sensors are usually available in B6, A4, A3 sizes or approximately 100 mm to 300 mm. The image sensors produce an analog signal that is commonly called a video signal. Illumination for sheet-fed and other types of scanners (e.g., flatbed scanners, slides scanners) and duplex scanners may be produced using light emitting diodes (LED), cold cathode fluorescent light (CCFL) tubes, electro-luminescent screens or filament lamps, for example. Color dropout (the elimination of a color) may be produced by using color filters that block a selected wavelength or by selecting light sources that generate the selected wavelength. 
     In both of the scanners shown in FIGS. 1 and 2, however, the document  1  is dragged across the surface of the glass covering the image sensors  2 ,  5 . The document  1 , however, may be soiled, and have abrasive particles clinging thereto. The document  1  moreover, even though apparently unsoiled, may itself contain abrasive impurities therein. In addition, the ink used on the document  1  may not be fully dry and may leave an oily residue on the image sensor transparent (typically glass) surface. These abrasive particles, impurities and residues may, with repeated usage, scratch and obscure the surface of the glass covering the image sensors  2 ,  5 , thereby degrading the quality of the resulting scanned image. This scratching may be further exacerbated by the roller  3 ,  6  pressing the document  1  against the glass of the image sensors  2 ,  5  with too great a pressure. The quality of the scanned images may also suffer from the effects of parasitic ambient light impinging upon the image sensors  2 ,  5 . Such ambient light may reach the sensors  2 ,  5  as the sensors  2 ,  5  are not protected therefrom, particularly when the leading edge of the document  1  is dragged across the sensors  2 ,  5 . 
     What are needed, therefore, are improved scanners that do not suffer from the forementioned disadvantages. Specifically, what are needed are document scanners with improved resistance to such soiling, scratching or obscuring of the image sensor glass. What are also needed are document scanners and associated document feeding mechanism that eliminate or reduce the amount of parasitic ambient light that is allowed to reach the scanner sensors. 
     SUMMARY OF THE INVENTION 
     An object of the present invention, therefore, is to provide document scanners that are resistant to such soiling, scratching or obscuring of the sensor glass or other corresponding transparent surface. It is another object of the present invention to provide a document scanner having an improved document feeding mechanism that introduces the document into the scanner at an optimal angle and at an optimal pressure to eliminate or reduce the glass scratching problems often associated with conventional document scanners, even when subjected to heavy usage patterns. Such a document scanner should also protect the image sensors from parasitic ambient light, thereby resulting in an improved scanned image quality. 
     In accordance with the above-described objects and those that will be mentioned and will become apparent below, a document scanner, according to an embodiment of the present invention, comprises: 
     an image sensor, the image sensor including a transparent surface over an optical focus line; 
     a feed roller motor; 
     a rotatable feed roller coupled to the feed roller motor, the feed roller being adapted to contact said transparent surface along a contact line that is offset from said optical focus line; and 
     a generally U-shaped deep input guide clip, the deep input guide clip including a plurality of retaining bends to clip onto the image sensor and including a document facing surface defining an opening aligned with the transparent surface, the retaining bends precisely locating the optical focus line relative to the contact line. 
     According to further embodiments, the deep input guide clip may be shaped from a single sheet of material, such as plastic or sheet metal. The generally U-shaped deep input guide clip may include a pair of facing arms extending from a closed portion of the U-shape, the pair of facing arms being resiliently biased toward one another. The deep input guide clip may include a plurality of spaced cutouts adapted to trap dust as a document is introduced into the scanner. A plurality of document proximity sensors may also be included to detect the leading edge, width and trailing edge of the document introduced into the scanner, the proximity sensors being secured within the deep input guide clip. The proximity sensors may be secured within the deep input guide clip by selected ones of the retaining bends and by proximity sensor folds integral to the deep input guide clip, an active portion of each of the plurality of document proximity sensors being aligned with a corresponding one of the plurality of spaced cutouts. An edge of the document facing surface may be disposed so as to scrape the document as it is introduced into the scanner. The optical focus line may be disposed between the edge of the document facing surface and the contact line, the pressure on the document during a scanning operation being greater at the contact line than at the optical focus line. A primary input guide may be provided, including a generally planar first surface angled relative to the document facing surface, and a generally arcuate second surface facing the feed roller in close proximity therewith and having a curvature generally matching that of the feed roller. In this manner, the primary input guide constrains a path of the document between the first surface and the document facing surface and prevents the feed roller from catching the document until the document is deeply engaged within the scanner. The image sensor may include a contact image sensor and the plurality of document proximity sensors may include infrared sensors. 
     The present invention may also be viewed as a one-piece deep input guide clip to secure an image sensor of a document scanner, the guide clip including a closed portion from which a pair of facing arms extend, the facing arms being resiliently biased toward one another and including a plurality of retaining bends to clip onto and precisely locate at least an image sensor between the pair of facing arms, the guide clip further including a document facing surface, the document facing surface defining a plurality of cutouts adapted to trap dust and to provide openings for document proximity sensors. 
     According to still further embodiments, the document facing surface further defines a transparent surface opening to accommodate a transparent surface of the image sensor. The deep input guide clip may be formed of either plastic or sheet metal. The closed portion may define at least one proximity sensor fold extending between the facing arms to secure, in combination with at least one of the plurality of retaining bends, a document proximity sensor assembly. Each of the plurality of retaining bends may be formed, for example, by cutting out three sides of a rectangular window in one arm of the pair of facing arms and pushing a remaining portion of the window toward the other arm of the pair of facing arms. A first retaining bend of the plurality of retaining bends may be located at the free extremity of one of the facing arms and may form a continuous rail along a width thereof, the rail being configured to clip onto the image sensor. One or more second retaining bends of the plurality of retaining bends may be shaped as. a slender extension bent at a free extremity thereof to clip onto the image sensor. 
     A document scanner, according to another embodiment of the present invention, comprises: 
     image sensing means, the image sensing means including a transparent surface over an optical focus line; 
     feed roller motor means; 
     a rotatable roller means coupled to the feed roller motor means, the feed roller means being adapted to contact said transparent surface along a contact line that is offset from said optical focus line; and 
     deep input guide clip means, the deep input guide clip means including means for precisely locating the optical focus line relative to the contact line such that a pressure on a document during a scanning operation is greater at the contact line than at the optical focus line. 
     According to further embodiments, the pressure on the document at the optical focus line may be substantially null. The deep input guide clip means may include a plurality of integral retaining bend means to clip onto the image sensor means, and may include a document facing surface defining an opening aligned with the transparent surface, the integral retaining bend means precisely locating the optical focus line relative to the contact line. The deep input guide clip means may be shaped from a single sheet of material, such as plastic or sheet metal. The deep input guide clip means may be generally U-shaped and may include a pair of facing arm means extending from a closed portion of the U-shape, the pair of facing arm means being resiliently biased toward one another. The deep input guide clip means may include a plurality of dust trap means to trap dust as a document is introduced into the scanner. A plurality of document proximity sensor means may also be provided to detect a leading edge, width and trailing edge of a document introduced into the scanner, the proximity sensor means being secured within the deep input guide clip means. The proximity sensor means may be secured within the deep input guide clip means by selected ones of a plurality of retaining bend means integral to the guide clip means and by at least one proximity sensor fold means integral to the deep input guide clip means, an active portion of each of the plurality of document proximity sensor means being aligned with a corresponding one of the plurality of dust trap means. Scrapping means may also be provided to scrape the document as it is introduced into the scanner. A primary input guide means may include a generally planar first surface angled relative to a surface of the deep input guide clip means adapted to face the document; and a generally arcuate second surface facing the feed roller means in close proximity therewith and having a curvature generally matching that of the feed roller means. In this manner, the primary input guide means constrains a path of the document between the first surface and the document facing surface and prevents the feed roller means from catching the document until the document is deeply engaged within the scanner. The image sensor means may include a contact image sensor and the plurality of document proximity sensor means may include infrared sensors. 
     The foregoing and other features of the invention are described in detail below and set forth in the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a further understanding of the objects and advantages of the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying figures, in which: 
     FIG. 1 is a perspective view of the major mechanical elements of a sheet-fed scanner. The electronics circuits that control the scanner and the communication link with the host computer are not represented. 
     FIG. 2 is a perspective view of the major mechanical elements of a duplex scanner. The electronics circuits that control the scanner and the communication link with the host computer are not represented. 
     FIG. 3A is a perspective view of the major components of a sheet-fed scanner including a deep input guide clip, according to an embodiment of the present invention. 
     FIG. 3B is a side view of the sheet-fed scanner of FIG.  3 A. 
     FIG. 4 is an exploded view of a sheet-fed document scanner including a deep input guide clip according to an embodiment of the present invention. 
     FIG. 5 is a perspective view of a deep input guide clipped onto an image sensor (e.g., CIS), according to an embodiment of the present invention. 
     FIG. 6 is a sectional view showing a deep input guide clip according to an embodiment of the present invention, when there is no document being driven between the feed roller and the transparent surface of the image sensor. 
     FIG. 7 is a sectional view showing a deep input guide clip according to an embodiment of the present invention, showing a document being driven between the feed roller and the contact image sensor glass. 
     FIG. 8 is a detailed perspective view of a deep input guide clip for document scanners, according to an embodiment of the present invention. 
     FIG. 9 shows the deep input guide clip of FIG. 8, further rotated to clearly show the plurality of dust trap cutouts. 
     FIG. 10 shows the document proximity sensor assembly with a plurality of infrared proximity sensors and their relative position with the image sensor and the transparent surface of the image sensor. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 3A and 3B are a perspective and a side view, respectively, of a sheet-fed scanner including a deep input guide clip according to an embodiment of the present invention. The scanner frame, motor, gears, controller, power module and other associated electronic circuits are not shown, for clarity of illustration. For example, the scanner according to the present invention may advantageously be controlled by and incorporate the controller disclosed in the commonly assigned U.S. patent application Ser. No. 08/931,131 now U.S. Pat. No. 6,344,906, entitled “Universal Document Scanner Controller” filed on Sep. 16, 1997, the disclosure of which is hereby incorporated herein by reference in its entirety. Also, the scanner according to the present invention may advantageously be powered by and incorporate the power module disclosed in the commonly assigned U.S. Pat. No. 5,847,948, entitled “Scanner Power Module”, the disclosure of which is hereby incorporated herein by reference in its entirety. 
     According to an embodiment thereof, the scanner according to the present invention includes a deep input guide clip  10 , an image sensor  11 , a feed roller  12 , a document proximity sensor assembly  14  and may include a primary input guide  44 , exemplars of the latter being shown in FIGS. 6 and 7. As shown in FIGS. 3A and 3B, the deep input guide clip  10  clips onto the image sensor  11 . According to an embodiment of the present invention, the image sensor  11  may be maintained in its proper position and orientation solely by the deep input guide clip  10 , to which the image sensor  11  is removably clipped. In turn, the deep input guide clip  10  may be fastened to the scanner frame (not shown) to secure the assembly thereto. The rotatable feed roller  12  is coupled to a feed roller motor, an example of which is shown in FIG. 1 at reference numeral  4 . In operation of the scanner according to the present invention, a document  13  (generally a paper document, although the present invention is not limited thereto) is pressed against a transparent surface  17  of the image sensor  11  by the feed roller  12 . The transparent surface  17  of the image sensor  11  may be formed of glass or any other suitable (hard and scratch resistant) transparent material. The transparent surface  17  is disposed over and protects the active scanning elements (not shown) within the image sensor  1 . The image sensor  11  may include, for example, a CIS. The document  13  is fed over the transparent surface  17  of the image sensor  11  in the direction of the arrow  15  when the feed roller  12  is rotated in the direction indicated by the arrow  16 . The feed roller  12  may also be rotated in the direction opposite that indicated by the arrow  16 , whereupon the document  13  will be ejected from the scanner in the direction opposite that indicated by arrow  15 . A document proximity sensor assembly  14  (which may include, for example, infrared sensors) may be held in place inside the deep input guide clip  10 . The proximity sensor assembly  14  may detect the leading edge, the width and the trailing edge of the document  13 . The feed roller  12  is adapted and positioned to contact the transparent surface  17  of the image sensor at least when no document  13  is inserted into the scanner. When a document  13  is inserted into the scanner, the document  13  is advanced past the transparent surface  17  of the image sensor  11  and is gripped by the feed roller  12 . The rotating feed roller  12  then advances the document  13 , the leading edge, width and trailing edge of the document  13  being detected by the document proximity sensor assembly  14 . When the document  13  is advanced past the image sensor  11 , at least a portion of the feed roller is no longer in contact with the transparent surface  17 , being in contact with the document  13  instead over at least a portion of its length. 
     As shown in FIGS. 3A and 3B, the deep input guide clip  10  has a generally U-shape, formed by a closed portion  25  from which extend a pair of facing arms  26  to at least partially encircle the image sensor  11 . To help secure the image sensor  11  between the two facing arms  26  of the deep input guide clip  10 , the pair of facing arms  26 , according to an embodiment of the present invention, may be resiliently biased toward one another, as best shown in FIG. 3B, wherein it can be seen that the arm  26  closest to the feed roller  12  is not parallel to the adjacent surface of the image sensor  11 . The deep input guide clip  10  may be shaped from a single sheet of material, such as for example, sheet metal or plastic. Alternatively other suitably stiff and resilient materials may be employed. Shaping the deep input guide clip  10  from a single, substantially homogeneous sheet of material reduces the manufacturing steps required to produce the part and thus decreases manufacturing costs, thereby reducing the overall cost of the assembled scanner unit. 
     FIG. 4 shows the constituent elements of the scanner represented in FIGS. 3A and 3B in an exploded view for easier identification. As shown therein, the deep input guide clip  10  includes a document facing surface  27  that defines an opening  28  (also shown in FIGS. 8 and 9) that is aligned (see FIG. 3A) with the transparent surface  17  of the image sensor  11 . FIG. 5 shows how the deep input guide clip  10  is clipped around and to the image sensor  11 . The deep input guide clip  10  is precisely maintained in position around the image sensor  11  by a plurality of retaining bends, exemplars thereof being shown at reference numerals  33 ,  34 ,  35  and  36 . The deep input guide clip  10  includes other similar retaining bends that are not visible in the figures. According to an embodiment of the present invention, the retaining bends  36  are integrally formed in a one-piece deep input guide clip  10 . Indeed, the retaining bends  36  according to the present invention may be formed, for example, by cutting out three sides of a rectangular window from the facing arms  26  and pushing in the partially cut out portion toward the facing arm  26 . Likewise, the retaining bends  33 ,  35  may be integrally formed in the one-piece deep input guide clip  10  and may be formed by bending the free extremities of the arms  26  toward each other to form bracket-shaped bends adapted to clip onto and support the image sensor  11 . The document proximity sensor assembly  14  may be clipped and secured into the deep input guide clip  10  by a combination of a plurality of proximity sensor folds  18  and one or more of the retaining bends  36 . The proximity sensor folds  18  may be formed in a manner similar to the retaining bends  36 ; i.e., by cutting out three sides of a rectangular window from the closed portion  25  of the generally U-shaped deep input guide clip  10  and pushing in the partially cut out portion inward (between the facing arms  26 ). The retaining bends  33 ,  34 ,  35 ,  36  and the proximity sensor folds  18  may be shaped differently than illustrated in the figures and formed by methods other than described herein without, however, departing from the scope of the present invention. 
     FIG. 6 is a sectional view showing the deep input guide clip  10  clipped on the image sensor  11  when there is no document  13  being driven between the feed roller  12  and the transparent surface  17  of the image sensor  11 . A document  13  is shown in FIG. 6, albeit not inserted between the transparent surface  17  and the feed roller  12 . In this configuration, the feed roller  12  may be directly in contact with the transparent surface  17  of the image sensor  11  at the point of contact indicated at  19 . It is to be understood that the point of contact  19 , over the length of the feed roller  12 , forms a corresponding line of contact. According to an embodiment of the present invention, the primary input guide  44  includes a generally planar first surface  29  angled relative to the document facing surface  27  of the deep input guide clip  10 . The primary input guide  44  may also include a generally arcuate second surface  30  facing the feed roller  12  in close proximity therewith and having a curvature generally matching that of the outermost surface (the surface adapted to contact the transparent surface  17 ) of the feed roller  12 . According to the present invention, the primary input guide  44  covers much of the outermost surface the feed roller  12  such that the leading edge  31  of the document  13  cannot contact the (e.g., rubber) outermost surface of the feed roller  12 . In this manner, the leading edge  31  of the document  13  may be guided such as to penetrate as deeply as possible between the document facing surface  27  of the deep input guide clip  10  and the feed roller  12  before the feed roller  12  is rotated in response to a signal from the document proximity sensor assembly  14 . That is, the primary input guide clip  10  constrains the path of the document  13  between the first surface  29  and the document facing surface  27  of the input guide clip  10  and prevents the feed roller  12  from catching the document  13  until it is deeply engaged within the scanner. 
     When a document  13  is inserted in the direction  15 , its leading edge  31  is gently pushed over the deep input guide edge  20 . As soon as the constituent sensors (shown in FIG. 10) of the document proximity sensor assembly  14  detect the entry of a document  13 , the electronics circuits driving the image sensor  11  begin monitoring the video signal that is generated from the line of pixels that is sensed at an optical focus line located at the point indicated by the arrow  21 . The optical focus line  21  is the line at which the active elements of the image sensor  11  sense the light (through the transparent surface  17 ) reflected from the document  13 . According to the present invention, the optical focus line  21  is slightly offset from the line of contact  19  of the feed roller  12  with the transparent surface  17  and/or the document  13 . When there is no document  13  passing over the optical focus line, the feed roller  12  (e.g., the black rubber outermost surface thereof) is detected. When the document leading edge  31  passes over the optical focus line  21 , the document  13 . (most often of a lighter color than the outermost surface of the feed roller, such as white) is detected by the image sensor  11  and the feed roller  12  may be immediately rotated as soon as a uniform document edge  31  corresponding to the document width derived by the constituent proximity sensors  24  (see FIG. 10) of the document proximity sensor assembly  14  is detected at the optical focus line  21 . Associated anti-skew auto-start systems (not shown) may ensure that the document  13  is perfectly aligned before the scanner document feed is enabled. When the document  13  is properly aligned, the feed roller  12  may be automatically activated to initiate a scanning operation, thus ensuring that the resulting scanned image is always free of skew. Advantageously, the scanner according to the present invention may incorporate the anti-skew auto-start system disclosed in the commonly assigned U.S. patent application Ser. No. 08/904,337, entitled “Anti-Skew Auto-Start System For Document Scanners” filed on Jul. 31, 1997, the disclosure of which is incorporated herein by reference in its entirety. 
     FIG. 7 is a sectional view showing the deep input guide clip  10  clipped on the image sensor  11  when a document  13  is driven between the feed roller  12  and the transparent surface  17  of the image sensor  11 . The contact line  19  is the tangent to the transparent surface  17  of the image sensor  11  and the outermost surface of the feed roller  12 . According to the present invention, maximum pressure is exercised by the feed roller  12  onto the document  13 /transparent surface  17  along the contact line indicated at  19 . It follows that abrasive impurities on or within the document  13  will have a tendency to scratch the transparent surface  17  (e.g. glass) of the image sensor  11  along the contact line  19 , the line at which maximum pressure is exerted. Therefore, maximum soiling of the transparent surface  17  of the image sensor may occur at and/or around this contact line  19  of maximum feed roller pressure. 
     The edge  20  of the deep input guide clip  10  keeps the document  13  from making close contact with the transparent surface  17  in the area of the transparent surface  17  between the contact line  19  and the edge  20  of the document facing surface  27 . In this area, the pressure of the document  13  against the transparent surface  17  is less than at the contact line  19  and may be almost null. Indeed, the pressure on the document  13  during a scanning operation is, according to the present invention, greater at the contact line  19  than at the optical focus line  21  of the image sensor  11 . Therefore, scratching of the transparent surface  17  thereof due to document impurities and soiling by non-dry oily ink may be reduced or avoided altogether. To further prevent soiling of the transparent surface  17  at and/or around the focus line  21  of the image sensor  11 , the edge  20  of the document facing surface  27  of the deep input guide clip  10  may be sharp, to thereby act as a scrapper to remove or flatten ink buildups and/or other protruding impurities. Therefore, the transparent surface  17  over the active sensing elements of the image sensor  11  at and/or around the optical focus line  21  will tend to remain clean and unscratched, and the scanner will not require frequent cleaning to maintain the quality of the resulting scanned images. The deep input guide clip  10  according to the present invention has the added benefit of stopping parasitic ambient light and protecting the image sensor against hard falling objects, thus avoiding breakage of the transparent surface  17 . 
     FIG. 8 shows a detailed perspective view of the deep input guide clip  10 . The deep input guide clip  10  may be advantageously produced from a single piece of precision sheet metal. The retaining bends  33 ,  34 ,  35  and  36  are clearly visible. The location of the retaining bends  33 ,  34 ,  35  and  36  (and other similar retaining bends not visible in the perspective drawings) are precisely determined so as to precisely locate the optical focus line  21  (See FIGS. 6 and 7) relative to the contact line  19  of the feed roller  12  against the document  13  and/or the transparent surface  17  of the deep input guide clip  10 . According to an embodiment of the present invention, the retaining bend  35  may be formed as a continuous rail along one of the facing arms  26 , thereby lending rigidity to the deep input guide clip  10 . Retaining bends  33 ,  34 ,  35  and/or  36  having shapes other than illustrated may also be employed. As shown in FIG. 8, the retaining bends  33 ,  34  formed from the document facing surface  27  of the deep input guide clip  10  may be shaped as slender extensions bent at their extremities to clip onto the image sensor  11  (not shown in FIG. 8) and to provide the opening  28  through which the transparent surface  17  of the image sensor  11  may appear. 
     FIG. 9 is a view of the deep input guide clip oriented such as to clearly show an embodiment of the present invention wherein the document facing surface  27  defines a plurality of spaced cutouts  22  adapted to trap dust as the document  13  (not shown in FIG. 9) is introduced into the scanner. Some or all of these cutouts  22  may also form retaining bends, such as shown at  36  in FIG. 8, to precisely located the image sensor  11  and/or the document proximity sensor assembly  14  therein. The cutouts  22  may, as shown in FIG. 9, be regularly spaced along the document facing surface  27  of the deep input guide clip  10 . 
     FIG. 10 shows the document proximity sensors assembly  14  with six constituent proximity sensors  24  (other numbers of sensors may also be employed), and their relative position with the contact image sensor  11  and the transparent surface  17 . The proximity sensors  24  may include, for example, infrared sensors. The sensors  24  and their associated circuit board  23  may be precisely held in place in the deep input guide clip  10  by the retaining bends  36  and/or the proximity sensor folds  18  (FIG.  5 ). The proximity sensors  24  may be secured, according to the present invention, within the deep input guide clip  10  by selected ones of the retaining bends  36  and/or proximity sensor folds  18  integral to the deep input guide clip  10 . The active portion of each of the plurality of document proximity sensors  24  may be aligned with a corresponding one of the plurality of spaced cutouts  22 . 
     While the foregoing detailed description has described preferred embodiments of the present invention, it is to be understood that the above description is illustrative only and not limiting of the disclosed invention. For example, the shape and position of the retaining bends  33 ,  34 ,  36  of the deep input guide clip  10  may differ from that described and illustrated herein. Still other modifications may occur to those of skill in this art. Thus, the present invention to be limited only by the claims as set forth below.