Abstract:
The present invention provides an optics module for a scanning device such as a portable scanner. The optics module includes an illumination source and guide that transmits light through an optical window of the scanning device casing before reflecting off of the object to be scanned. The reflected light from the object travels back through the optical window and a lens before reaching a photosensor for evaluation by an associated microprocessor. The optical window of the scanning device provides a recessed portion in the scanning device casing. The recessed portion of the window is formed using the functional components of the optics module to eliminate a piece of glass typically used within the optical window that can be easily scratched or broken and provides a loss during the illumination process. By using the functional components of the optics module to form the recessed optical window, manufacturing costs to secure and replace a typical glass window contained therein can be eliminated, size of the optics module is reduced, and any contaminates that gather around the optics module can be easily removed by the user.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to optical scanner devices and, more particularly to a cost effective and functionally efficient optics module and scan window for an optical scanner device. 
     2. Description of the Related Art 
     Optical scanners are well-known in the art to produce machine-readable data that can represent an image contained on an object, e.g. a page of printed text. In general, the data is obtained from an optics module reflecting a beam of light off of a “scan line” region of the object being scanned. When an optics module is used in a portable scanner, the reflected beam of light is obtained as the user physically moves the optical scanner across the object with their hand. Consequently, the optics module for hand-held or portable scanning devices must generally be very compact and often employ a navigational assembly to track and associate what portion of the object has been scanned. 
     Referring to FIG. 1, the basic components of a portable scanner are shown. The scanner  5  includes an optics module  10  having a scanning assembly  12  and a navigational assembly  14  coupled to an image processing system  30 . With each assembly, an illumination device  16 , such as one or more LED&#39;s, creates a beam of light  18 A,  18 B that passes through the scanner casing  20  at a scan window  22 A,  22 B having a transparent material  32 . Next, the beam of light  18 A,  18 B reflects off of the surface of the object  24  being scanned before reflecting back through the scan window  22 A,  22 B. The reflected beam of light  18 A′,  18 B′ is focused by a lens  26  and received by an illumination sensor or photosensor  28 . 
     The photosensor  28  works with other electronic components  30  to evaluate and translate the reflected beam of light  18 A′,  18 B′ into an electronic copy of the image contained by the object  24 . The electronic components  30  could include a microprocessor, memory and related translational software that is contained by the scanner or by a personal computer being accessable by a data cable. 
     With the conventional optics modules described above, the illumination source  16  radiates light over a full hemisphere, so only a small portion of the light is directed toward the scan region, and the light flux per unit angle is relatively low. Consequently, if the illumination source  16  is tilted or moved slightly away from the object  24 , the illumination level through the scan window  22 A and  22 B at the scan line falls rapidly, resulting in an undesirably dark image or a very non-uniform image to be captured by the photosensor  28 . 
     The transparent material  32  is made from plastic or glass and functions as a seal in the casing so that the optical and electronic components contained therein can be protected from dust, moisture and other potential contaminants that could possibly damage the operation of the scanner. The transparent material provides optical losses due to surface reflections and internal transmissions. In particular, each time a beam of light  18 A or  18 A′ passes through the transparent material, the beam of light is diminished by about 8%. An anti-reflective coating may be applied to the transparent material to reduce the optical losses, however this will only reduce the optical loss to about 1.5%. 
     FIG. 2 illustrates a cross-sectional view of how the transparent material  32  may be secured to the scanner casing  20 . In particular, FIG. 2 shows how the casing  20  can be manufactured to provide a scan window  22 A,  22 B that includes a ledge for supporting the transparent material  32  with an adhesive  36 . With this structure, the transparent material  32  is positioned a depth “d”, between 0.02-0.05 mm, away from an outer surface  38  of the casing  20  to create a recessed border defined by square comer regions  40 . 
     The recessed border is not deep enough to prevent a staple or a hard particle contained on an object from scratching the transparent material while the object is being scanned. In addition, the square comer regions  40  collect dust and other contaminants in areas that are hard to clean. Consequently, the scratches and collected contaminants further increase optical losses in the operational scanner. In turn, such optical losses may force the user to have the manufacturer replace the transparent material, which is not only time consuming, but costly. Lastly, the square comer regions  40  may cause the comers of the object being scanned to become jammed along the recessed borders of the scan window during the scanning process. 
     Thus, it would be desirable to provide an apparatus that overcomes the above problems associated with an optics module and scan window for a scanning devices. 
     SUMMARY OF THE INVENTION 
     In one embodiment, the present invention provides an optical scanner having a casing. The casing includes a scan window, a substrate attached within the casing and being laterally spaced from the scan window, and an optics module coupled between the scan window and the substrate to form a recess within the casing. 
     In another embodiment, the present invention provides a method for manufacturing a recessed scan window for use in an optical scanning apparatus having a casing. The method includes: forming a contact window within a scan surface of the apparatus casing; securing a substrate within the apparatus casing; coupling a first end of an illumination device to the substrate and a second end adjacent to a first portion of the contact window; and coupling a first end of a photosensor component to the substrate and a second end adjacent to a second portion of the contact window, wherein the second end of the illumination device and the photosensor component forms the recessed scan window. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other aspects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which: 
     FIG. 1 illustrates a schematic side view of a conventional portable scanner; 
     FIG. 2 illustrates a cut-away view of the scan window of FIG. 1; 
     FIG. 3 illustrates an isometric view of a portable scanner according to a first embodiment of the present invention; 
     FIG. 4 illustrates a cross-sectional view of FIG. 3 taken along reference line  4 ; 
     FIGS. 5A and 6A illustrate a plan view of the scanning surface in accordance with the first and a second embodiment of the present invention; 
     FIGS. 5B and 6B illustrate a detailed cut-away view of the optics module in accordance with the first and second embodiment of FIGS. 5A and 6A, respectively, taken along reference lines  5 B and  6 B; and 
     FIG. 7 illustrates a high-level block diagram of the image processing system in accordance with the present invention for the above embodiments. 
     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. 
     In general, the present invention provides an efficient, effective and reliable means for a photoelectric imaging system to obtain machine-readable data, which represents an image on an object, e.g. a page of printed text. More specifically, the present invention provides an optics module for a portable scanner having an illumination and photosensor component coupled between a substrate and a scan window. The illumination component creates a beam of light that can pass through the scan window and reflect off of a portion of an object (“scan line”) being positioned under the scan window. The reflected beam of light passes back through the scan window before being received by the photosensor component and evaluated/manipulated by complimentary imaging electronics and software. 
     The optical loss in the embodiments of the present invention are significantly less than the optical loss in conventional optic modules because the inventive optics module allows for the beam of light to pass and reflect through the scan window without having to pass through a transparent material. This is possible because the inventive structure uses the components of the optics module to define a recess within the scan window that can prevent the electronic components of the portable scanner from operational contaminants or scratching. By eliminating the use of the transparent material, the inventive optics module is less expensive to manufacture and dimensionally smaller in size. The inventive structure for the optics module can be similarly used for a navigational assembly of the optics module. 
     Turning now to the drawings, FIG. 3 illustrates a portable scanner  110  in accordance with the present invention. As shown, the hand-held scanner  110  may be used to scan an image  118  of object  114 , such as a piece of paper having a surface  116  with written text thereon. The image  118  is scanned by moving the scanner  110  over the document surface  116  in a scan direction generally indicated by arrow  120 . The handheld scanner  110  may include an elongated housing or casing  122  for containing the various internal components and systems required for the operation of the scanner, as will be described in greater detail below. 
     The front side  123  of casing  122  may include a display  128 , such as a liquid crystal display (“LCD”), for displaying data and/or function options of the scanner. In addition, the front side  123  may provide a plurality of function buttons  130 , scrolling buttons  132 , an enter button  134 , a scan button  135  and an on/off switch  136 . The buttons  130  may be used to control the various functions of the hand scanner  110  including: to initiate and terminate scanning of the image  118 , to transfer a scanned image to a computer being coupled by a data cable, to zoom in on or out of the displayed image, and to delete a scanned image from memory. 
     Referring now to FIG. 4, a cut-away view of the portable scanner  110  is shown as taken along reference lines  4  of FIG.  3 . As illustrated, the interior  146  of casing  122  is adapted to receive the optics module  150 , the LCD  128 , a power source  156 , and an image processing system (“IPS”)  158 . In general, the optics module  150  includes a scanning assembly  159  and an area  170  for containing a navigational assembly  174 , if desired (see FIG. 6B or  7 B). The optics module does not require a navigational assembly to operate, nor does the navigational assembly take-up as much room in the casing  122  as the scanning assembly  159 . 
     As will be described in more detail below, the scanning assembly  159  illuminates a scanning region or scan line  152  with an array of light emitting diodes (“LEDs”)  160  and a light guide  162 . The scanning region  152  is within a scan window  164  of scanning surface  138 . The light used to illuminate the scan region  152  is reflected off of the document surface  116  and received by a lens  166 . The lens  166  carries the reflected light to photosensor  168 . 
     The IPS  158  (a block diagram of which is illustrated in FIG. 8) receives data signals from the photosensor device  168  and processes the data signals as necessary to produce digital image data that the user can view on the display  128 . The IPS  158  may also control the other functions and operations of the scanner  110 , as described above. The above components are coupled to one another in a conventional manner. The casing  122  of scanner  110  may be manufactured by a conventional method, such as injection molding and include other components and/or systems that may be necessary or desirable for the hand scanner apparatus  110  to operate. 
     For further detail regarding the components and operational systems of a Handheld or portable optical scanner, the following references are incorporated herein for all that they disclose: U.S. Pat. No. 5,381,020 of Kochis, et al., for “Hand-Held Optical Scanner with Onboard Battery Recharging Assembly,” U.S. Pat. No. 5,306,908 of McConica for “Manually Operated Hand-Held Optical Scanner With Tactile Speed Control Assembly”, and U.S. Pat. No. 5,936,238 of David Bohn for “Portable Optical Scanning Device With A Recessed Optical Window.” 
     Referring to FIGS. 5A and 5B, the scanning surface  138  and optics module  150  are shown. In this embodiment, the scanning surface  138  provides a scan window  164  for the scanning assembly  159  and a navigational window  176  for the navigational assembly  174 . The scan window  164  provides a recess  165  being defined by the scanning window  164 , the light guide  162 , the lens  166  and the reflective material  178  on either side of the light guide and lens. Similarly, the navigational window  176  provides a recess  177  being defined by navigational window  176 , the light source  182 , the lens  184  and the reflective material  178  on either side of the light source and lens. The navigational assembly  174  is laterally separated from the scanning assembly  159  by the reflective material  178  being coupled between the casing  122  and substrate  196 . 
     During the operation of the scanning assembly  159  of FIGS. 5A and 5B, the illumination source  160  produces a ray of light that follows a light path  1 . The light path  1  internally reflects from the sides of the solid light pipe and follows reflected light paths  1 ′ out of the solid light pipe and optics module  150  to a scan region  152  under the lens  166 . Image light  1 ′ being reflected from the object  114 , travels along a light path r where it is focused by the lens  166 , such as a “SELFOC” lens, before reaching the photosensor  168 . The optical detector  168  produces electrical signals representative of the image light for the IPS  158  (see FIG. 4) to process and manipulate for display or downloading. 
     At the same time, the navigational assembly  174  detects and tracks movement of the optic module  150  over the object  114 . More specifically, each light source  182 , such as an LED, creates a beam of light (“N 1 ”) that is reflected off of the document surface  116  in a direction parallel with the length (“N 1 ”) of scan window  164 . Next, the navigational sensor  186  receives the reflected light (“Nr”) through the navigational lens  184 . The navigational sensor  186  uses the reflected light (“Nr”) to provide position information, which is paired with the swaths of image data provided by the optical detector  168 . A stitching algorithm can then use the position information to create a complete image of the object  114  from the scanned image swaths. 
     Referring now to FIGS. 6A and 6B, an alternative structure is shown for the optics module  150  of FIGS. 4,  5 A and  5 B. In this embodiment, the optics module  300  rotates the navigational window  176  and recess  170  of FIGS. 5A and 5B by 90 degrees. This rotation allows the lens  166  of the scanning assembly  159  to receive the light beam of the navigational light source  182  after being reflected off of the document surface  116  being scanned. With this embodiment, the known properties of a “SELFOC” lens are used to separate and guide the reflected light beams of the scanning assembly and navigational assembly to their respective photosensors  168  and  186 . In other words, with this embodiment, the same components and structure is used for the scanning assembly as described above, however the navigational lens  184  is eliminated for the navigational assembly and the navigational scan path is rotated 90 degrees. 
     During the operation of the optics module  300  of FIGS. 6A and 6B, the illumination sources  160  and  182  produce a ray of light that follows a light path  1  and N 1 , respectively. Similar to the previous embodiment, light produced by illumination source  160  is captured by light guide  162 . The captured light internally reflects from the sides of the light guide to follow light paths  1  and  1 ′ out of the solid light pipe, through the scan window  364  and onto a scan region  352  under the lens  166 . In contrast, the light from the navigational light source follows the light path N 1  through the scan window  364  and onto a scan region  352  under the lens  166 . Consequently, light from each illumination source  160  and  182  follows a light path r and Nr, respectively, through the lens  166  to the optical detectors  168  and  186 . The known properties of the lens  166  allows for each source of light entering into the lens at a different angle to be captured by their respective photosensor  168  and  186  upon their exit from the lens. The optical detectors  168  and  186  transfer the reflected light to the IPS  158  so that electrical signals can be produced to represent the image light. 
     The above embodiment allows for further cost and space reductions over the first embodiment by eliminating the need for a navigational lens  184  and window  176  (see FIGS.  5 A and  5 B). Consequently, less space is needed on the substrate  196 , less reflective material  178  will be used, and the weight and power consumption of the scanner will be reduced. 
     The component layout and operation for a preferred and alternative embodiment of the present invention have been described above. The following will provide more detail for each component used by both embodiments. The reflective material used in the above embodiment is conventional, such as a black plastic, and couples to the distal end of the scanning and navigational assembly components by a conventional method to seal each recess from contaminants reaching any other surface of the components contained by the casing  122 . In addition, the reflective material provides a smooth radii surface structure within each recess to avoid the accumulation of dust or other contaminants from gathering at the inner comers  190 , to provide easy cleaning, and to prevent the edge of a document surface  116  (see FIG. 4) from catching on the outer comers  192  while being scanned (see FIGS.  4  and  5 B). If desired, the reflective or containing material  178  could be removed so that only the lens  166  and light guide would define the recess of the scan window. 
     In the specific embodiments of the instant invention, the width (“W”) of the scan windows  164  and  364  is approximately 1-4 mm for the length (“L”) of the scanning region  152 . This distance is wide enough to permit a scan line of data to be obtained, but sufficiently narrow to prevent the document from bowing up into the recess portion  165 . The depth “D” of the recessed portions  165  and  365  is between about 1.5 and 5 mm. This depth should eliminate the chance of a staple or a particle on the document surface  116  from scratching any component of the scanning assembly. 
     The width and length of the navigational windows  176  in FIGS. 5A and 5B is much smaller than the width and length of the scanning windows  164  and  364 . This is primarily due to the fact that the navigational windows  176  are laterally spaced from each other along the length “L” of the scanning window  164 . In turn, the navigational window  176  only has to accommodate a light beam “N 1 ” from a single LED  182  that reflects off of the object  114  in the direction of the length “L” before being received by a navigational lens that feeds the reflected light “Nr” to the navigational photosensor  186 . The depth of the navigational window  176  (i.e., the distance from the scanning surface  138  to the surface of the lens  184  closest to the scanning surface  138 ) may be between about 3 to 5 mm. 
     The image detectors or photosensors  168  and  186  and the illumination sources  160  and  182  mount to a single substrate  196 , such as a printed circuit board (“pcb”). The printed circuit board  196  is preferably mounted to the casing  122 , which provides a compact structure for the optics module  150 . The pcb  196  may also include a plurality of conductors, such as printed circuit paths (not shown), to electrically connect the various LEDs  160  to a suitable connector node or pad (not shown) on pcb  196 . The connector node or pad (not shown) in turn may be connected to a suitable LED driver circuit, such as a pulse width modulation circuit, by any of a wide variety of electrical conductors, such as flexible insulated wire, etc. Lastly, pcb  196  may include a pair of spot-light LEDs  182  for the navigational assembly  177 . 
     The illumination source  160  may include an array of light emitting diodes (“LEDs”) arranged along an elongate surface of the pcb  196 . The lens  166  for the scanning assembly is preferably a “SELFOC” lens, manufactured by NSG (“Nippon Sheet Glass”). The lens  184  for the navigational assembly of the embodiment of Figures  5 A and  5 B is preferably a conventional bi-convex single element imaging lens made by plastic injection molding from materials such as acrylic polycarbonate. Each lens directs and focuses reflected light from the object  114  onto the optical detector  168 . The photo sensor  168  is a conventional CMOS linear array. 
     The light guide  162 , positioned under the illumination source  160 , is mounted to the lens  164  and the casing  122 . In a preferred embodiment, the light guide  162  comprises a solid light pipe. The solid light pipe may be made from any substantially transparent material having an index of refraction greater than that of air. As a result of the index of refraction, light rays may pass into and out of the solid light pipe only when the rays are at near normal angles with respect to the sides of the light pipe. Any light rays striking the sides of the solid light pipe with angles of incidence greater than the critical angle of incidence for the light pipe material will be internally reflected. 
     The top of the solid light pipe is perpendicular to the preferred direction of illumination of the scan region, such as along the illustrated reflected light path. Stray light baffles or reflectors may be placed alongside the illumination source to direct the light rays into the solid light pipe. In addition, the top of the solid light pipe may be slightly textured if desired to diffuse the light from the illumination source  160  as it enters the light pipe. For further details about light guides that may be implemented with the present invention, see U.S. patent application Ser. No. 09/477,205 of David Bohn for “Contact Image Sensor With Light Guide,” which is hereby incorporated by reference for all that it discloses. 
     Referring to FIG. 7, a description of the image processing system  158  will now follow. However, since the details of the IPS  158  are not necessary to understand or practice the present invention, the particular circuit components or the functions that they provide will only be generally described below. 
     Essentially, the image processing system  158  may comprise a microprocessor assembly  400  conventionally coupled to a memory system  402  for collecting and processing the image data provided by the scanning and navigational photosensors  168  and  186 . As mentioned earlier, the various function buttons  130 , scrolling buttons  132 , enter button  134 , scan button  135 , and on/off switch  136  are also connected to the microprocessor  400  having a power supply  156 , such as two ‘AA’ or ‘AAA’ batteries or power cord. The various buttons interact with a software program executed by the microprocessor  400  to control the various functions and operations of the scanner  110 . 
     The display system  128  is also connected to the microprocessor  400  and may be used to show the user data relating to the scanning operation. Of course, the photosensors  168  and  186  are also connected to the microprocessor  400  having an input/output (I/O) port  406  to allow data to be exchanged with external devices, such as a computer (not shown). I/O port  406  may comprise a standard serial or USB port or may comprise an infrared port. 
     With either embodiment, the inventive optics module for a scanning apparatus can produce a quality digital image of a scanned object. In particular, once the user turns on the power  136  and activates the scan button  135 , the IPS will activate the scanning processes as described above. If the length (“L”) of the scanning window  164  is not as wide as the object  114  to be scanned, the optics module  150  is swept over the object  114  in a curvilinear or meandering fashion during a scanning operation. This sweeping action produces connected image strips or swaths which must then be stitched together by a stitching algorithm to produce a complete image of the object  114 . 
     Examplary navigation systems and stitching algorithms that could be used with the present invention are disclosed in U.S. Pat. No. 5,644,139 of Allen et al. for “Navigation Technique for Detecting Movement of Navigation Sensors Relative to an Object”, U.S. Pat. No. 6,002,124 of Bohn et al. for “Portable Image Scanner with Optical Position Sensors,” and U.S. patent application Ser. No. 09/343,880 of David Bohn et al. for “Integral Positioning and Imaging Device” filed Jun. 30, 1999, all of which are specifically incorporated herein by reference for all that they disclose. 
     In summary, the optics module of the above embodiments may be used in any imaging device such as a scanner or fax machine to capture the image of an object. The above inventive structure eliminates the need for a transparent material to be positioned between the document surface and the components of the optics module. Consequently, the user will not experience optical losses due to particles or staples on the document surface that typically scratch a transparent material used to seal the casing and protect the components of the optics module. In addition, the combination of the depth, narrow width and smooth radii at the comers of the recessed scan window, permits the scan surface to flatten the document without the document bowing into the recessed window and helps to prevent dust particles from accumulating in the recessed scan window. If contaminants do collect, the user can easily clean the recessed scan window. 
     In a conventional optics module, the LEDs typically radiate light over a very wide range of directions, most of which are not aimed at the scan line. The light guide of the instant invention redirects this light toward the scan line. Correspondingly, the light guide reduces stray light inside the optics module and provides improved depth of illumination of the scan region on the object. 
     The inventive optics module having the light guide directs the light from the illumination source onto the scan region so that even if the optics module is tilted or moved slightly away from the object, the image does not darken as rapidly. Since the light is more focused and directed toward the scan region, the flux per unit angle is greater and the intensity does not drop off as quickly with an increase in distance from the illumination source. The light guide also reduces the non-uniform spot-light effect which increases with distance as a conventional optics module is moved away from the object. 
     The inventive optics modules are more compact and less expensive than previous optics modules. Without a light guide, the illumination source is typically mounted on a separate circuit board that is positioned close to the scan region at an angle. In addition, a transparent material is positioned within the scan window of the casing to protect the closely positioned illumination source. The light guide removes the need for an additional circuit board, with its attendant wires, electrical interconnect and mounting hardware, and the need for the transparent material that can be easily scratched and collect contaminants. The optics module with a light guide and without a transparent material is thus simpler to assemble, costs less, and is less prone to failure. The optics module with a light guide allows a smaller and lighter scanner, fax machine, or other imaging device.