Patent Publication Number: US-RE48604-E

Title: Scanner module and image scanning apparatus employing the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/741,581 filed Jan. 15, 2013, which is pending, which is a continuation of U.S. patent application Ser. No. 12/183,714, filed Jul. 31, 2008, which issued Jan. 22, 2013 as U.S. Pat. No. 8,358,447, and claims the benefit of Korean Patent Application No. 2007-0076640, filed on Jul. 31, 2007, and Korean Patent Application No. 10-2008-0065047 filed on Jul. 4, 2008, which is a continuation of U.S. patent application Ser. No. 12/118,856 filed on May 12, 2008, which issued Jul. 10, 2012 as U.S. Pat. No. 8,218,205 and which claims the disclosure of the benefit of Korean Patent Application No. 2007-0076640, each of which is incorporated herein by reference in its entirety.This application is a reissue application of U.S. patent application Ser. No. 14/227,648, filed on Mar. 27, 2014, issued as U.S. Pat. No. 9,179,029 on Nov. 3, 2015, which is a continuation of application Ser. No. 13/741,581, filed on Jan. 15, 2013, which issued as U.S. Pat. No. 9,204,006 on Dec. 1, 2015, which is a continuation of application Ser. No. 12/183,714, filed on Jul. 31, 2008, which issued as U.S. Pat. No. 8,358,447 on Jan. 22, 2013, which is a continuation of application Ser. No. 12/118,856, filed on May 12, 2008, which issued as U.S. Pat. No. 8,218,205 on Jul. 10, 2012, and which claims the benefit of Korean Application No. 10-2007-0076640, filed on Jul. 31, 2007 and Korean Application No. 10-2008-0065047, filed on Jul. 4, 2008, in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field 
     The present invention relates to a scanner module and an image scanning apparatus employing the scanner module, and, more particularly, to a mounting structure of a light guide in a scanner module. 
     2. Description of the Related Art 
     Generally, a scanner module may be employed in an image reading apparatus to read image from a desired portion of a document. To this end, a scanner module may include an illuminator to irradiate light to the portion of the document to be read and a focusing lens to focus the light reflected from the portion of the document on an image sensor. 
     With recent development of inexpensive high-luminous-intensity white light-emitting diodes, a scanner module employing white light emitting diodes as the light source has been developed. 
     An illuminator however also needs to have an appropriate light distribution to provide a uniform image output for each pixel. For this reason, a light guide has been used to guide light, irradiated from light emitting diodes, to the desired illuminating position. 
     An example of an illuminator that employs light emitting diodes and a light guide, is disclosed in U.S. Pat. No. 6,357,903 B1 to Furusawa et al. (“Furusawa”), which was issued on Mar. 19, 2002). 
     In legacy illuminators, e.g., one described by Furusawa, a light source is provided at one end of an elongated transparent light guide that is mounted in a case by being slid lengthwise into the case. During the lengthwise insertion onto the case, damages to the light guide suffer, e.g., scratches, or the like, which may have adverse effect on the scanning performance. In addition, there is no structure to guide the light guide into the proper mounting position, exacerbating the possibility of damages, and resulting in imprecise assembly. 
     When light emitting diodes are used as the light source of an illuminator, the luminous intensity may be limited to a predetermined level. While a higher current or voltage is supplied to the light emitting diodes may result in the light emitting diodes producing light with enhanced luminous intensity, the increased power also raises the temperature of the light emitting diodes, and, consequently, may deteriorate the luminous intensity of light actually emitted by the light emitting diodes. 
     Moreover, it is desirable that an illuminator be easy to assemble so as to allow mass production. A conventional light guide is formed as an elongated transparent member, which is prone to bending or bowing. It is thus also desirable to provide a guide holder that is capable of supporting the light guide while maintaining the light guide straight. 
     Furthermore, in the above-described conventional illuminator, both ends of the light guide are fixedly supported, causing the light guide to bend or bow along its length when the light guide lengthens due to thermal expansion by heat generated from the light source. These deformation or damages, e.g., bending or scratches, or the like, of the light guide causes variation in characteristics of light emitted therethrough, and adversely affects the scanning performance and/or quality. 
     SUMMARY 
     Additional aspects and/or advantages of one or more embodiments will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of one or more embodiments of disclosure. One or more embodiments are inclusive of such additional aspects. 
     Therefore, one or more embodiments relate to an illuminator for use in an image scanning apparatus to illuminate light on an object to be scanned. 
     In accordance with one or more embodiments, an illuminator for use in an image scanning apparatus to illuminate light on an object to be scanned may include a light source configured to produce the light, a light guide having an elongated shape with its length extending along a first direction, the light guide being configured to receive the light from the light source, and to change a direction of the received light, a light source holder to mount the light source to the light guide, and at least one elastic member elastically supporting at least one of longitudinal ends of the light guide. 
     A light guide according to one or more embodiments may include an incidence face formed on at least one longitudinal end of the light guide, the light guide receiving the light from the light source through the incident face, and the elastic member elastically supports the light source, so as to cause the light source to be in close proximity to the incidence face of the light guide. 
     The elastic member may support the light source and may be disposed so as to elastically bias the light source toward the incidence face of the light guide. 
     The elastic member may be made of a thermally conductive material. 
     The elastic member may include a metallic leaf spring. 
     The elastic member may be made of a resin material, and a radiating member made of a thermally conductive material may be provided between the elastic member and the light source holder. 
     The illuminator may be integrally formed with a body of a scanning module, and the radiating member may extend outward from between the elastic member and the light source holder, and may be fixed to the body of the scanner module. 
     An illuminator according to one or more embodiments may include a thermal coupling provided between a light source holder and a radiating member. 
     The light source holder may have a hole through which the light source is exposed. 
     An illuminator according to one or more embodiments may further include a guide holder having formed thereon a mounting recess into which the light guide may be received, the guide holder may further include a light source mounting portion in which the light source holder is mounted, and the elastic member may be provided between a wall surface of the light source mounting portion and the light source. 
     The elastic member may include an elastic portion convexly raised to exhibit an elastic force, and supporting portions formed at both sides of the elastic portion to allow the elastic member to be supported at both ends of the light source mounting portion. 
     An illuminator according to one or more embodiments may further include a guide holder having formed thereon a mounting recess into which the light guide may be received, the mounting recess possibly including an entrance portion, through which the light guide enters the mounting recess, and at least one supporting protrusion formed at the entrance portion of the mounting recess to protrude into the mounting recess to, when the light guide is received in the mounting recess, be in an interfering contact with the light guide to restrict movement of the light guide in at least a second direction perpendicular to the first direction. 
     The light guide may be received into the mounting recess in a second direction substantially perpendicular to the first direction. 
     The elastic member may comprise a pair of elastic members, each of which pair supporting a corresponding respective one of the longitudinal ends of the light guide. 
     In accordance with one or more embodiments, a scanning module for use in an image scanning apparatus for scanning an object may include an illuminator configured to illuminate a light on the object to be scanned; and a sensor configured to detect the light reflected from the object. The illuminator may include a light source configured to produce the light, a light guide having an elongated shape with its length extending along a first direction, the light guide being configured to receive the light from the light source, and to change a direction of the received light, a light source holder to mount the light source to the light guide; and at least one elastic member elastically supporting at least one of longitudinal ends of the light guide. 
     The light source may face the incidence face of the light guide and the elastic member may support the substrate opposite a side of the substrate on which the light source is disposed so as to elastically bias the light source toward the incidence face of the light guide. 
     The elastic member may be made of a thermally conductive material. 
     The elastic member may be made of a resin material, and a radiating member made of a thermally conductive material is provided between the elastic member and the light source holder. 
     The scanning module may further include a thermal coupling provided between the light source holder and the radiating member. 
     The scanning module may further include a guide holder having formed thereon a mounting recess into which the light guide may be received. The guide holder may further include a light source mounting portion in which the light source holder may be mounted, and the elastic member may be provided between a wall surface of the light source mounting portion and the light source holder. 
     The elastic member may include a pair of elastic members, each of which pair may support a corresponding respective one of the longitudinal ends of the light guide. 
     In accordance with one or more embodiments, an image scanning apparatus may include a scanner module, a controller configured to control an operation of the scanner module. The scanner module may include an illuminator configured to illuminate a light on an object to be scanned, and a sensor configured to detect the light reflected from the object. The illuminator may include a light source configured to produce the light, a light guide having an elongated shape with its length extending along a first direction, the light guide being configured to receive the light from the light source, and to change a direction of the received light, a light source holder to mount the light source to the light guide, and at least one elastic member elastically supporting at least one of longitudinal ends of the light guide. 
     The light source may be facing the incidence face of the light guide and the elastic member supporting the light source may be disposed so as to elastically bias the light source toward the incidence face of the light guide. 
     The elastic member may be made of a thermally conductive material. 
     The elastic member may be made of a resin material, and a radiating member made of a thermally conductive material may be provided between the elastic member and the light source holder. 
     In accordance with one or more embodiments, an image scanning apparatus may further include a thermal coupling provided between the light source holder and the radiating member. 
     In accordance with one or more embodiments, an image scanning apparatus may further include a guide holder having formed thereon a mounting recess into which the light guide is received. The guide holder may further include a light source mounting portion in which the light source holder may be mounted, and the elastic member may be provided between a wall surface of the light source mounting portion and the light source holder. 
     The elastic member may include a pair of elastic members, each of which pair may support a corresponding respective one of the longitudinal ends of the light guide. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. 
       Various aspects and advantages of the embodiments of the invention will become apparent and be more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, of which: 
         FIG. 1  is a sectional view illustrating optical arrangement of a scanner module in accordance with an embodiment of the present invention; 
         FIG. 2  is a perspective view of the scanner module in accordance with an embodiment of the present invention; 
         FIG. 3  is an exploded perspective view illustrating an illuminator in accordance with a first embodiment of the present invention; 
         FIG. 4  is a perspective and partial sectional view of portions of the illuminator of  FIG. 3 ; 
         FIG. 5  is a sectional view of the illuminator of  FIG. 3 ; 
         FIG. 6  is a perspective view illustrating an embodiment of a light source holder of the illuminator of  FIG. 3 ; 
         FIG. 7  is a sectional view of the portion “A” of  FIG. 6 ; 
         FIG. 8  is a partial sectional view illustrating coupling of a guide holder and light source holder shown in  FIGS. 2-7   
         FIG. 9  is a block diagram illustrating an image scanning apparatus employing a scanner module in accordance with an embodiment of the present invention; 
         FIG. 10  is a perspective and a partial sectional view of an illuminator in accordance with a second embodiment of the present invention; 
         FIG. 11  is an exploded and a partial sectional view of relevant portions of an illuminator in accordance with a third embodiment of the present invention; 
         FIG. 12  is an exploded perspective view illustrating a scanner module including an illuminator in accordance with a fourth embodiment of the present invention; 
         FIG. 13  is a plan view illustrating coupling of a light source and light source holder provided in the scanner module shown in  FIG. 12 ; 
         FIG. 14  is a view illustrating numerical analysis results of deformation of a light guide in response to thermal expansion of the light guide when no elastic member is provided; 
         FIG. 15  is a view illustrating numerical analysis results of deformation of a light guide in response to thermal expansion of the light guide when elastic members are provided; 
         FIG. 16  is a graph comparing temperatures of a light source in both cases where the light source is elastically supported by metal elastic members and where no elastic member is provided; 
         FIG. 17  is a sectional view illustrating an embodiment of the mounting of the light guide mounted in an illuminator; 
         FIG. 18  is a view illustrating numerical analysis results of deformation of a light guide in response to thermal expansion of the light guide when no supporting protrusion is provided; 
         FIG. 19  is a view illustrating numerical analysis results of deformation of a light guide in response to thermal expansion of the light guide when supporting protrusions are provided; and 
         FIG. 20  is an exploded perspective view illustrating a scanner module including an illuminator in accordance with a fifth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. While the embodiments are described with detailed construction and elements to assist in a comprehensive understanding of the various applications and advantages of the embodiments, it should be apparent however that the embodiments can be carried out without those specifically detailed particulars. Also, well-known functions or constructions will not be described in detail so as to avoid obscuring the description with unnecessary detail. 
       FIG. 1  is a sectional view illustrating optical arrangement of a scanner module  10  according to an embodiment of the present invention. Referring to  FIG. 1 , the scanner module  10  may be devised to scan an image across a sub scanning direction X. The scanner module  10  includes an illuminator  110 , which irradiates a light to a document platform D, a focusing lens  120 , which focuses the light reflected from a scan object P, such as a document, or the like, disposed on the document platform D, and a sensor unit  130 , which receives the light focused by the focusing lens  120  and senses an image based on the received light. The scanner module  10  further includes a scanner module body  100  having an inner space in which the focusing lens  120  and the sensor unit  130  may be housed. A seating recess  100 a (See  FIG. 2 ) may provided on the top portion of the scanner module body  100  for accommodating the illuminator  110 . 
     The illuminator  110  serves to irradiate light to the scan object P. As shown in  FIGS. 2 and 3 , the illuminator  110  may include light source of sources  111  that produce the light, and light source holders  112  to which the light sources  111  are mounted. The illuminator  110  may further include light guides  113 , the lengths of which extend along a main scanning direction Y (orthogonal to the sub scanning direction X), and which are arranged to face and oppose the document platform D. The illuminator  110  may further include a guide holder  114  having light guide mounting portions  114 a for mounting of the light guides  113  and light source mounting portions  114 b for mounting of the light source holders  112 . 
     Referring again to  FIG. 1 , the focusing lens  120  is located between the document platform D and the sensor unit  130 , and serves to focus the light reflected from the scan object P onto the sensor unit  130 . 
     The sensor unit  130  receives the light focused thereon by the focusing lens  120 , and serves to detect an image of the scan object P based on the received light. Depending on the particular scanning application, the sensor unit  130  may have a single-row configuration, or a multiple row configuration, for scanning of Red/Green/Blue color images or Red/Green/Blue/Black-and-White images. Specifically, the sensor unit  130  may include image sensors, e.g., charge coupled device (CCD) or complimentary metal oxide (CMOS) pixel elements, for respective colors, which are arranged in plural rows spaced apart from one another. 
     A plurality of reflecting mirrors  140  may further be provided between the scan object P and the focusing lens  120 . The reflecting mirrors  140  serve to define a light path within the inner space of the scanner module body  100 . To this end, the reflecting mirrors  140  reflect the light reflected from the scan object P, and change the light path to direct the light toward the focusing lens  120 . Providing the plurality of reflecting mirrors  140  may advantageously achieve the required light focusing distance between the scan object P and the sensor unit  130 , and may also result in a compact size of the scanner module body  100 . In the present embodiment, the scanner module  10  is provided with four reflecting mirrors  140 , but the present invention is not so limited, and any number of reflecting mirrors can be selected for a particular design. 
       FIGS. 2 to 5  are a perspective view, an exploded perspective view, a partial perspective view, and a sectional view, respectively, illustrating the illuminator employed according to the first embodiment of the present invention.  FIG. 6  is a perspective view illustrating the light source holder according to an embodiment.  FIG. 8  is a partial sectional view illustrating assembly of the guide holder and the light source holder shown in  FIGS. 2-6 . 
     Referring to the drawings, the illuminator  110  is employed in the scanner module  10 , to irradiate light to the scan object P, which is disposed on the document platform D, in the main scanning direction Y that is substantially orthogonal to the sub scanning direction X of the scanner module  10 . 
     The illuminator  110  includes light sources  111  producing light, the light source holders  112  to which the light sources  111  are mounted, the light guides  113  longitudinally arranged along the main scanning direction Y to face the document platform D, and the guide holder  114 , in which the light guides  113  are mounted. 
     Each of the light sources  111  may include a substrate  111 a mounted to the light source holder  112 , and light emitting diodes  111 b formed on the substrate  111 a to irradiate light upon receiving power through the substrate  111 a. In an embodiment, the light emitting diodes  111 b may be white light emitting diodes. 
     The light guides  113  change a direction of the light irradiated from the light sources  111 , so as to direct the light to an image reading region on the document platform D. In one embodiment, to enhance the luminous intensity of light to be directed to the image reading region, the plurality of light guides  113  may be provided. 
     The light guides  113  are made of a transparent material such as glass, plastic, or the like, and have an elongated shape, the length of which extending along the main scanning direction Y. Each of the light guides  113  includes at least one incidence face  113 a, guide faces  113 b and an emission face  113 c. 
     The incidence face  113 a receives the light from the corresponding light emitting diode  111 b. The incidence face  113 a is formed on at least one of both longitudinal ends of the respective light guides  113 . Here, the light source  111  is mounted to the light source holder  112  such that the light source  111  faces the incidence face  113 a of the light guide  113 . 
     The emission face  113 c opposes the document platform D, through which the light diffused and reflected by the guide faces  113 b is emitted. In one embodiment, the emission face  113 c may form a collimating lens. 
     The guide faces  113 b are formed at both longitudinal sides of the light guide  113 . If light is introduced through the incidence face  113 a via total internal reflection, the guide faces  113 b guide the direction of the light, allowing the light to be emitted throughout the emission face  113 c. 
     The reflecting face  113 d reflects the light, introduced thereto through the incidence face  113 a, toward the emission face  113 c. The reflecting face  113 d is formed at the light guide  113  at an opposite side of the emission face  113 c. For reflection of light, the reflecting face  113 d has a light reflecting pattern defined by convex and concave portions. 
     In the present embodiment, a pair of the light guides  113  is arranged to be adjacent to each other along the sub scanning direction X. The pair of light guides  113  may be tilted towards each other to direct the light to the image reading region without interfering with the light reflected from the scan object P. That is, as shown in  FIG. 1 , center axes C1 and C2 of light having passed through the two respective light guides  113  are tilted with respect to the center optical axis Z. 
     In the embodiment shown, a pair of the light sources  111  is provided for each of the light guides  113 , a pair of the light emitting diodes  111 b being installed on the substrate  111 a of each light source  111 . With this configuration, the two light emitting diodes  111 b of each of the pair of light sources  111  can irradiate the light on each incidence face  113 a formed at both ends of each of the pair of light guides  113 . 
     In addition, a light source holders  112  is provided on each longitudinal ends of the guide holder  114  such that a light source  111  is provided on each of the ends of each light guide  113 . When light is irradiated from the light source  111  provided at one end of a light guide  113 , and is introduced to the light guides  113  through the incidence faces  113 a facing the light source  111 , in order to prevent the light from leaking from the light guides  113  through the incidence faces  113 a at the other end, the pair of light source holders  112  are arranged to cover both incidence faces  113 a of the respective light guides  113 , the light source holders  112  being adapted to reflect the light. That is, the pair of light source holders  112  covers the pair of incidence faces  113 a of each light guide  113 , thereby preventing the light, introduced into the light guide  113  through the incidence faces  113 a of on one end, from leaking from the light guide  113  through the incidence face  113 a on the other end of the light guide  113 . 
     In an embodiment, preferably, the light source holders  112  are made of a white material to reflect and diffuse light, the material having a light reflectivity of 70% or greater. With adoption of the light source holders  112  to prevent the light, irradiated from the light sources  111  into the light guides  113 , from leaking from the light guides  113  through the incidence faces  113 a, the illuminator  110  can achieve greater luminous intensity of light using the same light sources  111 . 
     While the above embodiment is described to include a pair of light sources  111  at each end of the light guides  113  via the pair of light source holders  112 , but this configuration is given only as an example. Alternatively, a single light source  111  may be mounted to only one end of each of the light guides  113  via a single light source holder  112 . 
     According to an embodiment, the guide holder  114  may serve to guide mounting positions of the light guides  113  and the light sources  111 . To this end, the guide holder  114  is formed with at least one light source mounting portion  114 b to which the light source holder  112  may be mounted to provide a light source  111  on at least one end of each of the light guides  113 , and the light guide mounting portions  114 a in which the light guides  113  are to be mounted. 
     Each light guide mounting portion  114 a may be recessed into the guide holder  114  extending longitudinally along the main scanning direction Y, and has a shape corresponding to that of the light guide  113 . For example, in the embodiment shown, the light guide mounting portion  114 a may have a trapezoidal cross-sectional shape having an inwardly tapered cross section. In the embodiment, the pair of the light guide mounting portions  114 a are arranged adjacent each other along the sub scanning direction X, and extend parallel to each other along the main scanning direction Y such that the pair of light guides  113  can be mounted parallel to each other. 
     Preferably, the light guide  113  is inserted into the light guide mounting portion  114 a by being moved in a direction orthogonal to the longitudinal direction of the light guide  113 . If the light guide  113  is inserted into the longitudinal direction of the light guide mounting portion  114 a, scratches may occur on an outer surface of the light guide  113 . Inserting the light guide  113  in a direction orthogonal to the longitudinal direction thereof may reduce the possibility of scratching the light guides  113 . For example, in the embodiment shown, the light guide mounting portion  114 a has, e.g., a trapezoidal cross section with its height significantly smaller than its length. Therefore, when a light guide  113  is inserted into the light guide mounting portion  114 a along the height of the light guide mounting portion  114 a, i.e. orthogonal to the longitudinal direction of the light guide  113 , the contact distance between the light guide  113  and the light guide mounting portion  114 a may be substantially shorter that when the light guide  113  is received into the recess in lengthwise direction, and consequently, damage to the light guide  113  can be minimized. 
     The guide holder  114  may be made of a flexible material, which is elastically deformable in response to a pressing force. For example, before the light guide  113  is inserted into the light guide mounting portion  114 a, the light guide mounting portion  114 a, as represented by the dotted line in  FIG. 5 , may have a narrower initial inner space than the space required for mounting of the light guide  113 . 
     When the light guide  113  is received into the light guide mounting portion  114 a, as shown in  FIG. 5 , the light guide mounting portion  114 a expands by the insertion of the light guide  113 , preventing unwanted movement of the light guide  113  after installation. 
     According to an embodiment, the illuminator  110  may further include spacers  114 c provided on the inner surface of the light guide mounting portion  114 a to support the light guide  113 . 
     Once the light guide  1133  is inserted into the light guide mounting portion  114 a that includes the spacers  114 c, the light guide  113  can be supported by the spacers  114 c while allowing gaps between the light guide  113  and the inner surface of the light guide mounting portion  114 a. Providing the spacers  114 c may further alleviate the problem of incompletely supporting the light guide  113  due to spatial deformation of the light guide mounting portion  114 a resulting during manufacture of the guide holder  114 . This consequently reduce bending of the light guide  113 , and helps to maintain straightness of the light guide  113 . 
     A plurality of spacers  114 c may be spaced apart from one another along the longitudinal direction of the light guide  113 . For example, in the present embodiment, the spacers  114 c may be provided at the center and at opposite ends of the light guide mounting portion  114 a along its length. As shown in  FIG. 5 , the spacers  114 c may be arranged on the side wall surfaces and bottom surface of the light guide mounting portion  114 a, so as to support the light guide  113  in three directions. 
     When a pair of the spacers  114 c are arranged on the side wall surfaces of the light guide mounting portion  114 a, the distance between the spacers  114 c on opposite wall surfaces may be made smaller than the width of the light guide  113  to be located between the spacers  114 c. With this configuration, as the light guide  113  is inserted into the light guide mounting portion  114 a, the guide holder  114  is elastically deformed to provide a required installation space for the light guide  113 , and the light guide  113  can come into pressing contact with the respective spacers  114 c. In one embodiment, the spacers  114 c may be formed integrally with the guide holder  114 , which may improve assembly efficiency, and may reduce manufacturing costs. 
     The light source holder  112  may include a fixing portion  112 a to keep the light guide  113  in place. The fixing portion  112 a protrudes to have an inner contour corresponding to the contour of the emission face  113 c of the light guide  113 , and can be made to come into direct or indirect contact with the emission face  113 c of the light guide  113  so as to prevent vertical movement of the light guide  113 . 
     For example, as shown in  FIG. 6 , the light source holder  112  may further include a fixing rib  112 b formed on the inner edge surface of the fixing portion  112 a. Once the light guide  113  is mounted in the light guide mounting portion  114 a, the fixing rib  112 b may come into partial contact with the light guide  113 , and can keep the light guide  113  in position. 
     During the coupling of the light source holder  112  to the guide holder  114 , the fixing rib  112 b and the light guide  113  move relatively each other while being in contact, possibly causing the light guide  113  to be scratched. Thus, in one embodiment, the fixing rib  112 b may be tapered as shown in  FIG. 7 . The tapered fixing rib  112 b may reduce possible damages to the light guide  113  during the installation of the light source holder  112  in the guide holder  114 . 
     To address the possible thermal expansion of the light guide  113 , according to an embodiment shown in  FIG. 7 , the fixing rib  112 b may be provided with a neck portion  112 c, which forms a recessed portion between the fixing portion  112 a and the fixing rib  112 b. 
     If a greater pressure is applied to an outer surface of the fixing rib  112 b as the light guide  113  is thermally deformed, the neck portion  112 c allows elastic movement of the fixing rib  112 b. As a result, the light guide  113  can be stably supported at a fixed position without damaging the fixing rib  112 b. The structure of the neck portion  112 c is described only by way of an example for addressing thermal deformation of the light guide  113 , and does not limited the present embodiments to the particular structure. Various other shapes or structures can also be employed to account for the thermal expansion of the light guide  113 . For example, when the light source holder  112 , the fixing portion  112 a and/or the fixing rib  112 b itself is made of an elastically deformable flexible material, the light source holder  112  can also stably support the light guide  113 . 
     In addition, the illuminator  110  may further include positioning guides  112 d and  114 d to set the mounting position of the light source holder  112  relative to the guide holder  114 . The positioning guides,  112 d and  114 d are shaped to match each other, and are arranged to be opposing positions on the guide holder  114  and the light source holder  112 , respectively. When coupling the light source holder  112  to the guide holder  114 , the coupling position can be set on the basis of the positioning guides  112 d and  114 d, making rapid and accurate coupling between the guide holder  114  and the light source holder  112  possible. 
     Preferably, the light source holder  112  may be capable of being snap-fitted to the mounting portion  114 b of the guide holder  114 . Snap-fitting may not require any screws or bonding adhesives and, therefore, advantageously enables easy coupling. 
     The light source holder  112 , as shown in  FIG. 3 , can be coupled to the mounting portion  114 b in a direction substantially parallel the longitudinal direction of the light guide  113 . To that end, to mount the light source holder  112  in the mounting portion  114 b, hook members  112 e and holding protrusions  114 e may be provided. 
     The hook members  112 e, as shown in  FIGS. 6 and 8 , may extend from a surface of the light source holder  112  facing the guide holder  114 , and the holding protrusions  114 e may be provided at positions of the guide holder  114  corresponding to the mounted positions of the respective hook members  112 e. When the hook members  112 e engage the holding protrusions  114 e, the light source holder  112  may be coupled to the guide holder  114 . 
     While in the above embodiment, the light guide holder  112  is described to have formed therewith the hook members  112 e, and the guide holder  114  as including the holding protrusions  114 e, but the present invention is not so limited. For example, the respective locations of the hook members and holding protrusions may be reversed. 
     In addition, the hook members  112 e are not limited to the above-described configuration. For example, according to a second embodiment of illuminator shown in  FIG. 10 , each hook member  212 e of the light source holder  212  may be formed, at the distal tip end thereof, with a relatively large width portion while the light source mounting portion  214 b of a guide holder  214  may be provided with a recess having a shape corresponding to that of the hook member  212 e. Accordingly, the light source holder  212  can be coupled to the guide holder  214  as the hook member  212 e is snap-fitted in the mounting portion  214 b as shown in  FIG. 10 . 
     Referring to  FIG. 11  illustrating an illuminator according to a third embodiment, a light source holder  312  may be fitted into a mounting portion  314 b of a guide holder  314  in a direction orthogonal to the longitudinal direction of a light guide  313 . For example, an illuminator of this embodiment may further include hook members  312 e and holding protrusions  314 e, to stably fit the light source holder  312  into the mounting portion  314 b. 
     The hook members  312 e, as shown in  FIG. 11 , may protrude downward from side edges of the light source holder  312 , and the holding protrusions  314 e may be provided at positions of the guide holder  314  corresponding to the mounted position of the respective hook members  312 e. Accordingly, as the hook members  312 e engage the holding protrusions  314 e, the light source holder  312  can be coupled to the guide holder  314 . 
     When the light source holder  312  is coupled to the guide holder  314  in the above-described direction, as there is substantially no risk of the contact position between the fixing rib of the light source holder  312  and the light guide  313  being changed during assembly, the generation of scratches can thus be substantially avoided. 
     The above-described configuration of the illuminator, along with one or more features of previously described embodiments, advantageous allows precise positioning an/or quick coupling of the light guide  313  and the light source  311 . In addition, the light guide  313  can be firmly supported to maintain straightness thereof. 
     Although the illuminator  110  in accordance with the first embodiment of the present invention includes the guide holder  114  to be mounted into the scanner module body  100  after the light guides  113 , light sources  111  and light holders  112  are mounted to the guide holder  114 , the present invention is not so limited. For example, referring to  FIG. 12  illustrating an illuminator according to a fourth embodiment, instead of using the guide holder  114 , an illuminator  410  of a scanner module  40  includes light guides  413 , light sources  411  and light source holders  412 , and a scanner module body  400 , on which the light guide mounting portions  400 a for mounting of the light guides  413  and the light source mounting portions  400 b for mounting of both the light sources  411  and the light source holders  412  are provided. With this configuration, the light guides  413 , light sources  411  and light source holders  412  can be directly mounted into the scanner module body  400 . 
     The light guide mounting portions  400 a extend along the main scanning direction Y, i.e. in the longitudinal direction of the light guides  413 . The light source mounting portions  400 b are formed, at both ends of the light guide mounting portions  400 a, to have a larger width than the width of the light guide mounting portions  400 a. In the present embodiment, a pair of the light guides  413  are mounted in the scanner module body  400  such that they are parallel to each other in the sub scanning direction X, and for mounting of the pair of light guides  413 , a pair of the light guide mounting portions  400 a are provided parallel to each other in the sub scanning direction X. 
     In this embodiment, a light guide  413  is mounted in the light guide mounting portion  400 a in such a manner that at least one of the longitudinal ends thereof is elastically supported by an elastic member  414 . This serves to minimize deformation of the light guide  413  caused when the light guide  413  increases in length due to thermal expansion by heat generated from the light sources  411 . If the light guide  413  increases in length due to thermal expansion, the light guide  413  may become convexly deformed, or bowed, at the center of an emission face  413 c, causing variation in characteristics of light emitted through the light guide  413  and deterioration in image scanning performance. 
     By elastically supporting at least one of end of the light guide  413  using the elastic member  414 , even if the light guide  413  increases in length due to thermal expansion, the elastic member  414  can partially compensate for the increase in the length of the light guide  413  via elastic deformation thereof as shown in  FIG. 13 . This substantially reduces the emission face  413 c of the light guide  413  from being bent or bowed. 
       FIG. 14  is a view illustrating results of numerical analysis of deformation of the light guide  413  when both the ends of the light guide  413  are fixedly supported, and  FIG. 15  is a view illustrating results of numerical analysis of deformation of the light guide  413  when both ends of the light guide  413  are elastically supported by the elastic members  414 . 
     As can be seen from  FIGS. 14 and 15 , the light guide  413  has a deformation amount of about 0.021 mm when both the ends of the light guide  413  are fixedly supported, whereas the light guide  413  has a deformation amount of 0.012 mm when both the ends of the light guide  413  are elastically supported by the elastic members  414 . Accordingly, in this example, it can be appreciated that supporting both the ends of the light guide  413  via the elastic members  414  may reduce the deformation amount of the light guide  413  to about half. 
     When the length of the light guide  413  varies according to heat generated from the light sources  411 , an incidence face  413 a of the light guide  413  may become spaced further apart from a corresponding light emitting diode  411 b of the light source  411 . In this case, light loss may occur as the light irradiated from the light emitting diode  411 b passes through air between the light emitting diode  411 b and the incidence face  413 a. Therefore, to minimize the light loss, it is preferred that the incidence face  413 a provided at either end of the light guide  413  come into close contact with the corresponding light emitting diode  411 b of the light source  411 . 
     In an embodiment, to maintain the proper distance between the incidence surface  413 a and the light emitting diode  411 b, the light source  411  is mounted to either end of the light guide  413  via the light source holder  412 , and the elastic member  414  is provided between the light source  411  and a wall surface of the light source mounting portion  400 b to elastically support the light guide  413  indirectly by way of the light source  411 . When supporting the light guide  413  in this manner using the elastic member  414  with the light source  411  being interposed between the incidence surface  413 a and the elastic member  414 , the elastic member  414  can reduce the possible bowing of the light guide  413 , and may also allow the light emitting diode  411 b of the light source  411  to maintain a sufficiently close proximity to the corresponding incidence face  413 a of the light guide  413 , resulting in reduction of light loss. 
     In the present embodiment, although the light emitting diodes  411 b are mounted to the light source holder  412  in a state of being mounted on a substrate  411 a, the present invention is not limited thereto. For example, after the light emitting diodes  411 b are directly mounted to the light source holder  412  without a structure corresponding to the substrate  411 a, the light source holder  412  is elastically supported by the elastic member  414 , whereby the light emitting diodes  411 b can come into close contact with the incidence face  413 a of the light guide  413 . 
     Referring again to  FIG. 12 , the elastic member  414  according to an embodiment may be a leaf spring. The elastic member  414  in the form of a leaf spring consists of a center elastic portion  414 a, which is convexly raised to exhibit an elastic force so as to elastically support the light source holder  112 , and supporting portions  414 b which are defined at both sides of the elastic portion  414 a to allow the elastic member  414  to be supported in the light source mounting portion  400 b. The elastic member  414  may be made of a material exhibiting high thermal conductivity, such as metallic material, to thus serve, in addition to providing the elastic support, as a radiating member to radiate heat generated from the light source  411  away from the light source  411 . 
       FIG. 16  is a graph showing the measured temperatures of the light source  411  in both cases of when the metal elastic members  414  is used and when it was not. In the graph of  FIG. 16 , the dotted curve represents the temperature variation when the elastic member  414  was not used, and the solid curve represents the temperature variation when the metal elastic member  414  is used. As can be seen from the graph, in this example, the use of the metal elastic member  414  can lower the temperature of the light source  411  by approximately 17.degree. C. 
     According to an embodiment, to more effectively restrict the emission face  413 c of the light guide  413  from being deformed by heat generated from the light sources  411 , supporting protrusions  415  protrude from an entrance of the light guide mounting portion  400 a, so as to support a part of the emission face  413 c of the light guide  413 . 
     Specifically, the supporting protrusions  415  are integrally formed with the scanner module body  400 . The plurality of supporting protrusions  415  protrude in the sub scanning direction X and are spaced apart from one another in the main scanning direction Y. As shown in  FIG. 17 , when a part of the emission face  413 c of the light guide  413  is supported by the supporting protrusions  415 , the supporting protrusions  415  can restrict deformation of the light guide  413  even if the light guide  413  thermally expands due to heat generated from the light sources  411 . In the present embodiment, the pair of light guide mounting portions  400 a are arranged parallel to each other in the sub scanning direction X, and each supporting protrusion  415  protrudes in the sub scanning direction X from one side of the light guide mounting portion  400 a so as to support a part of the emission face  413 c of the light guide  413 . 
       FIG. 18  is a view illustrating numerical analysis results of deformation of the light guide  413  when not using the supporting protrusion  415 , and  FIG. 19  is a view illustrating numerical analysis results of deformation of the light guide  413  when using three supporting protrusions  415 . 
     As can be seen from  FIGS. 18 and 19 , in this example, the light guide  413  has a deformation amount of about 0.021 mm when the supporting protrusion  415  was not used, whereas the light guide  413  has a deformation amount of about 0.014 mm when the emission face  413 c of the light guide  413  is supported by the supporting protrusions  415 . Accordingly, it can be appreciated that use of the supporting protrusions  415  can substantially reduce the deformation amount of the light guide  413 . 
     As described above, when the light guide  413  is elastically supported by the elastic members  414  and/or when the emission face  413 c of the light guide  413  is supported by the supporting protrusions  415 , deformation of the light guide  413  can be reduced. Accordingly, to minimize deformation of the light guide  413 , as described with relation to the present embodiment, it is preferred that both the ends of the light guide  413  be elastically supported by the elastic members  414  and that the emission face  413 c of the light guide  413  be supported by the plurality of supporting protrusions  415 . 
     The supporting protrusions  415  provided at the entrance of the light guide mounting portion  400 a as described above, further, have the effect of preventing the light guide  413  from being separated from the light guide mounting portion  400 a even when subjected to vibration or shock during, e.g., transportation of the scanner module  40  or of a variety of appliances in which the scanner module  40  is included. 
     As a result of performing a drop test from a height of 30 cm, simulating a drop that may be experienced by the scanner module  40  during transport, under several conditions of different numbers of supporting protrusions  415 , the light guide  413  was separated from the light guide mounting portion  400 a when two supporting protrusions  415  were provided, but remained in the light guide mounting portion  400 a when three supporting protrusions  415  were provided. Accordingly, it is preferable that three or more supporting protrusions  415  be formed to protect against external vibration or shock, in order to prevent the light guide  413  from being separated from the light guide mounting portion  400 a of the scanner module body  400 . 
     Referring again to  FIG. 12 , a reflecting face  413 d provided at the light guide  413  has a convex and concave pattern. With this configuration, a part of the light, irradiated from the light emitting diodes  411 b and introduced into the light guide  413 , may leak from the reflecting face  413 d of the light guide  413  to the outside, causing light loss. Therefore, a reflecting plate  418  is disposed at the rear side of the reflecting face  413 d of the light guide  413 , to reflect the light, leaked from the reflecting face  413 d to the outside of the light guide  413 , toward the reflecting face  413 d, so as to allow the reflected light to be again introduced into the light guide  413  through the reflecting face  413 d. In the present embodiment, a pair of light guides  413  are provided and therefore, a pair of reflecting plates  418  are provided such that the reflecting plates  418  are provided at the rear side of the reflecting faces  413 d of the pair of light guides  413 , respectively. A supporting piece  418 a is formed at one side of each reflecting plate  418 , to be supported on one side of the light guide  413 . Through the supporting piece  418 a, the reflecting plate  418  can be stably mounted in the corresponding light guide mounting portion  400 a. 
     While an embodiment is described above to include an elastic member  414 , in the form of a metal leaf spring, to elastically supports the light guide  413  and the light source  411 , the present invention is not so limited. For example, an elastic member  514 , made of an elastic resin material such as rubber, may alternatively be used as shown in  FIG. 20 . 
     Referring to  FIG. 20 , the elastic resin member  514  may exhibit poor thermal conductivity, and may not be as effective in removing the heat generated by the light source  511 . In an embodiment, a radiating member  516 , made of material that has a sufficiently high thermal conductivity, may be provided between the elastic member  514  and the light source  511 . 
     One end of the radiating member  516  may be located between the elastic member  514  and the light source  511  while the other end of the radiating member  516  extends out of a light source mounting portion  500 b, and is mounted to a portion of the scanner module body  500 . The heat generated from the light source  511  is transferred along the radiating member  516 , and is radiated via heat exchange with air outside the light source mounting portion  500 b. As a result, heat generated from the light source  511  can be radiated. 
     In the above-described configuration, thermal conductivity between the light source  511  and the radiating member  516  is proportional to the contact area between the light source  511  and the radiating member  516 . When facing surfaces of the light source  511  and the radiating member  516  are not flat and thus, have a relatively small contact area between them, a thermal coupling  517  may be provided between the light source  511  and the radiating member  516  to enhance the transfer of heat generated from the light source  511  to the radiating member  516 . The thermal coupling  517  may be made of a material exhibiting high thermal conductivity, and may be configured to closely contact both facing surfaces of the light source  511  and the radiating member  516 . The thermal coupling  517  can indirectly maximize the contact area between the light source  511  and the radiating member  516 , and, consequently, can allow heat generated from the light source  511  to be effectively transmitted to and radiated by the radiating member  516 . 
     In the present embodiment, although the thermal coupling  517  is provided between the light source  511  and the radiating member  516 , when the light emitting diodes  511 b are directly mounted to the light source holder  512  without a structure corresponding to the substrate  511 a, the thermal coupling  517  may be provided between the light source holder  512  and the radiating member  516 . 
       FIG. 9  is a block diagram illustrating an image scanning apparatus employing a scanning module, various embodiments of which have been described above. Referring to the drawing, the image scanning apparatus may include the scanner module  10 , and an image processor  20  to process an image obtained from the scanner module  10 . Here, the image scanning apparatus in accordance with the present invention may include, e.g., a Multi-Functional Printer (MFP), a digital copier, a scanner, a facsimile, or the like. 
     The scanner module  10  is substantially identical to the embodiments variously described above, a detailed description of which need not be repeated. The image processor  20  may include at least one of a file producer  21  to produce an image file from an image obtained from the sensor unit  130  ( FIG. 1 ) and an image former  22  to form an image on a printing medium on the basis of the obtained image. 
     The file producer  21  may be, e.g., a controller that may also control operations of various components of the image scanning apparatus, including, e.g., the scanner module. To this end, according to an embodiment, the controller may be, e.g., a microprocessor, a microcontroller or the like, that includes a CPU to execute one or more computer instructions to implement the various control operations of the scanning apparatus, and may further include a memory device, e.g., a Random Access Memory (RAM), Read-Only-Memory (ROM), a flesh memory, or the like, to store the one or more computer instructions. The method in which the controller controls various components of an image scanning apparatus is similar to that of well-known image scanning apparatuses, detailed description thereof is thus unnecessary. 
     The image former  22  may include one or more of components of an image forming apparatus, for example, of an electro-photographic printing apparatus, that includes, e.g., a printing medium feeding unit that holds, picks up and feeds printing medium, an exposure unit for drawing a latent image using light on a photosensitive surface, a developing unit to develop the latent image with toner, a transfer unit to transfer the toner image onto the printing medium, a fixing unit to fuse the toner image sufficiently permanently on the printing medium and a discharging unit for discharging a printing medium on which an image has been fixed. As known to those skilled in the art, there are many available and known other various image forming mechanisms. 
     While the above embodiments are generally described in references to examples of a charge coupled device module (CCDM) type scanner module, in which a light source and a plurality of reflecting mirrors constitute a single module, the present invention is also applicable to other types of scanning module, including, e.g., a Mirror Moving Type (MMT), in which a light source and a single reflecting mirror constitute one module and two reflecting mirrors constitute another module. 
     Although embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.