Patent Publication Number: US-2009225377-A1

Title: Image reading apparatus and light source arrangement method

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC §119 from Japanese Patent Application No. 2008-052914 filed Mar. 4, 2008. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to an image reading apparatus that reads an image on a document, and a light source arrangement method. 
     2. Related Art 
     A document reading apparatus having a light source that irradiates a document linearly is known. 
     SUMMARY 
     According to an aspect of the invention, there is provided an image reading apparatus including: a light source that is provided with a light-emitting face emitting light to a document, that has a width, and that is formed in a lengthy shape; and a light receiving part that receives light emitted from the light source and reflected from a read part where the document is to be read. The light source is arranged with inclination to the document, and a normal line from a center part of the light-emitting face in a width direction is directed to a part other than the read part. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiment(s) of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is a diagram illustrating a configuration example of an image reading apparatus to which the present exemplary embodiment is applied; 
         FIGS. 2A and 2B  are diagrams for explaining the first light source and the second light source; 
         FIGS. 3A to 3C  are graphs in which the separate distance and the inclination angle are plotted when the light amount at the read part becomes the maximum as the separate distance and the inclination angle are changed; and 
         FIGS. 4A to 4C  are graphs in which the separate distance and the inclination angle are plotted when the light amount at the read part becomes the maximum as the separate distance and the inclination angle are changed on the condition that the width of the first light source and the like is set at 3 mm. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, a description will be given of exemplary embodiments of the present invention in detail with reference to attached drawings. 
       FIG. 1  is a diagram illustrating a configuration example of an image reading apparatus  1  to which the present exemplary embodiment is applied. With the image reading apparatus  1  shown in the figure, an image on a fixed document may be read and an image on a document being transported may also be read. The image reading apparatus  1  is provided with a document feeding device  10  that sequentially transports a document from a stacked bundle of documents and a reading device  50  that reads the image by scanning. 
     The document feeding device  10  that functions as one of the transporting units is provided with a document stacking part  11  that stacks a bundle of plural documents and an exit paper stacking part  12  that is provided below the document stacking part  11  and stacks the documents which have been read. In addition, the document feeding device  10  is provided with a nudger roll  13  that takes out and transports the documents in the document stacking part  11 . Further, on the downstream side of the nudger roll  13  in the document transporting direction, a sorting mechanism  14  that sorts paper sheets one by one by a feed roll and a retard roll is provided. In a first transport path  31  on which the documents are transported, pre registration rolls  15 , registration rolls  16 , a platen roll  17 , and out rolls  18  are provided in order from the upstream side in the document transporting direction. Moreover, inside the document feeding device  10 , a Contact Image Sensor (CIS) unit  80  is provided. 
     The pre registration rolls  15  transport a document sorted one by one toward rolls on the downstream side while forming a loop of documents. The registration rolls  16  stop rotation once and then, resume the rotation at right timing and supply documents while performing registration adjustment to the document reading unit, which will be described later. The platen roll  17  assists transportation of the documents being read by the reading device  50 . The out rolls  18  transport the documents read by the reading device  50  further to the downstream. In addition, on the downstream side of the out rolls  18  in the document transporting direction, a second transport path  32  that guides the documents to the exit paper stacking part  12  is provided. In the second transport path  32 , exit rolls  19  are provided. 
     When the documents are transported by the document feeding device  10 , a first face (one face) of the document is pressed onto a second platen glass  52 B, and an image on the first face is read by a CCD image sensor  59  that is an example of a light receiving part. On the other hand, the CIS unit  80  reads an image on a second face (the other face) from the other opposite side across the first transport path  31 . 
     Here, the CIS unit  80  is provided with a glass  81  arranged oppositely to the first transport path  31 , and a first light source  82   a  and a second light source  82   b  that irradiate the second face of the document with a light going through the glass  81 . In addition, a Selfoc lens (registered trademark)  83  focusing a reflected light from the document and a line sensor  84  (another example of the light receiving part) that reads the light focused by the Selfoc lens  83  are provided. As the line sensor  84 , a CCD or CMOS (Complementary Metal Oxide Semiconductor) sensor, a contact image sensor and the like may be used. Note that, for the first light source  82   a  and the second light source  82   b,  an EL element, whose details will be described later, may be used. In the CIS unit  80 , since an image is captured, not using a minification optical system but using a contact type optical system with the Selfoc lens  83  and the line sensor  84 , the structure may be simplified, the size of a housing may be reduced and power consumption may be lowered. 
     Further, in the image reading apparatus  1 , a third transport path  33  is provided between an outlet side of the out rolls  18  and an inlet side of the pre registration rolls  15  so that an image formed on both faces of the document may be read in one process. The above-mentioned exit rolls  19  have a function to reverse and transport the document to the third transport path  33 . 
     Still further, in the image reading apparatus  1 , a fourth transport path  34  is provided for reversing the document again and discharging the document to the exit paper stacking part  12  at discharge if the both faces of the document are read. The fourth transport path  34  is provided on an upper side of the second transport path  32 . The above-mentioned exit rolls  19  further has a function to reverse and transport the document to the fourth transport path  34 . 
     On the other hand, the reading device  50  supports the above-mentioned document feeding device  10  openably and closably, and supports the document feeding device  10  with a device frame  51 , and further reads an image on a document transported by the document feeding device  10 . The reading device  50  is provided with the device frame  51  forming a housing, a first platen glass  52 A on which a document having an image to be read is placed in a stationary state, and the second platen glass  52 B having an opening portion for light in order to read the document transported by the document feeding device  10 . Here, the second platen glass  52 B may be taken as a support part that has light permeability and supports the document. 
     In addition, the reading device  50  is provided with a full-rate carriage  53  that reads an image by staying below the second platen glass  52 B or by scanning across the entire first platen glass  52 A, and a half-rate carriage  54  that supplies a light obtained from the full-rate carriage  53  to an image forming part. Here, the full-rate carriage  53  is provided with a first light source  55 A and a second light source  55 B that irradiate the document with a light through the first platen glass  52 A and the like. 
     Further, in the full-rate carriage  53 , a first mirror  57 A that reflects a reflected light obtained from the document is provided. Here, the first light source  55 A is arranged on an upstream side of a light path from a read part, where the document is to be read, to the CCD image sensor  59  in a scan direction (upstream side in a slow scan direction), while the second light source  55 B is arranged on a downstream side of the light path in the scan direction (downstream side in the slow scan direction). Moreover, in the half-rate carriage  54 , a second mirror  57 B and a third mirror  57 C that provides light obtained from the first mirror  57 A to the image forming part are provided. 
     In addition, the reading device  50  is provided with a driving source such as a motor and the like and is provided with a moving mechanism (not shown in the figure) that moves the half-rate carriage  54  and the full-rate carriage  53  in the slow scan direction. Further, the reading device  50  is provided with an image-forming lens  58  and the CCD image sensor  59 . Among them, the image-forming lens  58  optically reduces an optical image obtained from the third mirror  57 C. Furthermore, the CCD image sensor  59  photoelectrically converts an optical image formed by the image-forming lens  58 . That is, in the reading device  50 , an image is formed at the CCD image sensor  59  using a so-called minification optical system. Moreover, in the reading device  50 , a guide  56 A that guides a document transported in the document feeding device  10  is formed between the first platen glass  52 A and the second platen glass  52 B, and below the guide  56 A, a white reference plate  56 B extending along a fast scan direction is attached. 
     Further, the reading device  50  is provided with a control/image processing unit  70 . The control/image processing unit  70  performs a processing to image data of the document inputted from the line sensor  84  provided in the CIS unit  80  and the CCD image sensor  59 . Furthermore, the control/image processing unit  70  controls operations of each part in a reading operation of the image reading apparatus  1  (the document feeding device  10 , the reading device  50 , and the CIS unit  80 ). Note that, the first light source  55 A, the second light source  55 B, the CCD image sensor  59  and the like in the present exemplary embodiment may be taken as a reading unit that reads an image on the first face (front face) of the document. 
     Here, for example, if an image on the document placed on the first platen glass  52 A is to be read, the full-rate carriage  53  and the half-rate carriage  54  move in the scan direction (arrow A direction) with a ratio of 2:1. At this time, the light is irradiated from the first light source  55 A and the second light source  55 B in the full-rate carriage  53  to the read part where the document is to be read. Then, the reflected light from the document is reflected at the first mirror  57 A. After that, the reflected light is reflected by the second mirror  57 B and the third mirror  57 C in this order and guided to the image-forming lens  58 . Thereafter, the light guided to the image-forming lens  58  forms an image on a light receiving face of the CCD image sensor  59 . The CCD image sensor  59  is a one-dimensional sensor and processes one line at a time. When reading of the one line in the line direction (fast scan direction of the scan) is finished, the full-rate carriage  53  is moved to a direction orthogonal to the fast scan direction (slow scan direction) so as to read the subsequent line of the document. By executing the above operation across the entire document size, document reading of one page is completed. 
     On the other hand, if an image on the document transported by the document feeding device  10  is to be read, the document transported by the document feeding device  10  passes over the second platen glass  52 B. At this time, the full-rate carriage  53  and the half-rate carriage  54  are in a stopped state at a solid-line position shown in  FIG. 1 . The reflected light of the first line of the document having passed the platen roll  17  of the document feeding device  10  is guided to the image-forming lens  58  via the first mirror  57 A, the second mirror  57 B, and the third mirror  57 C. 
     Then, the reflected light forms an image at the image-forming lens  58 , and the image is read by the CCD image sensor  59 . After the one line in the fast scan direction is processed at a time by the CCD image sensor  59 , which is a one-dimensional sensor, one subsequent line in the fast scan direction of the document transported by the document feeding device  10  is read. After that, by passage of a rear end of the document over a reading position of the second platen glass  52 B, reading of one page across the slow scan direction is completed. Here, in the present exemplary embodiment, when the first face of the document is read by the CCD image sensor  59 , the second face may also be read by the CIS unit  80  at the same time. 
       FIGS. 2A and 2B  are diagrams for explaining the first light source  55 A and the second light source  55 B. In these figures, the full-rate carriage  53  is not shown. 
     The first light source  55 A and the second light source  55 B in the present exemplary embodiment are formed in a flat-plate shape and in a lengthy shape, and in addition, in a plane type. Further, each of the first light source  55 A and the second light source  55 B has a certain width L and is arranged along the fast scan direction. Furthermore, each of the first light source  55 A and the second light source  55 B is constituted by a so-called electro-luminescence lamp (EL lamp (EL element)) composed of a substrate  60 A and a light emitting part  60 B formed on the substrate  60 A. Note that, the first light source  55 A and the second light source  55 B may be constituted using an existing art, and may be constituted by including a first electrode  601  arranged on the substrate  60 A side and formed transparently and having light permeability, a second electrode  603  arranged at a position opposite to the first electrode  601 , and a light-emitting layer  602  arranged between the first electrode  601  and the second electrode  603 , for example. In the first light source  55 A and the second light source  55 B, light is emitted from the substrate  60 A side. Thus, a surface of the substrate  60 A may be taken as a light emitting face. 
     Here, the first light source  55 A is arranged with inclination to the second platen glass  52 B (document to be transported). In addition, the first light source  55 A is arranged in an inclined state so that one end portion on the upstream side in the scan direction is closer to the second platen glass  52 B than the other end portion on the downstream side in the scan direction. Explaining in more detail, the first light source  55 A is arranged in an inclined state so that one side in a width direction is closer to the second platen glass  52 B than the other side. Further, the second light source  55 B is also arranged with inclination to the second platen glass  52 B. In addition, the second light source  55 B is arranged in an inclined state so that one end portion on the downstream side in the scan direction is closer to the second platen glass  52 B than the other end portion on the upstream side in the scan direction. Explaining in more detail, the second light source  55 B is arranged in an inclined state so that one side in the width direction is closer to the second platen glass  52 B than the other side. 
     Here, each of the first light source  55 A and the second light source  55 B arranged with inclination is arranged in a state having an angle α with respect to a reference line A in parallel with the second platen glass  52 B. Note that, the angle α corresponds to an alternate angle of an inclination angle of the first light source  55 A and the second light source  55 B with respect to the second platen glass  52 B (document). Thus, the angle α may be taken as an inclination angle of the first light source  55 A and the second light source  55 B with respect to the second platen glass  52 B (document). It should be noted that, in this specification, the angle α is hereinafter referred to as an inclination angle α. 
     Further, the first light source  55 A and the second light source  55 B are arranged with a distance X between them in the scan direction (slow scan direction). That is, the first light source  55 A and the second light source  55 B are arranged in a state of being separated from each other and having the distance X (hereinafter, the distance X between the first light source  55 A and the second light source  55 B is optionally referred to as a “separate distance X”). A light path to the CCD image sensor  59  is formed between the first light source  55 A and the second light source  55 B. Thus, the separate distance X is set at a length that may restrict interference between the light path and the first light source  55 A and the like caused by vibration during scanning, manufacturing tolerance and the like. Note that, the present exemplary embodiment may be taken as a configuration in which the first light source  55 A is arranged on one side relative to the light path and the second light source  55 B is arranged on the other side relative to the light path. Furthermore, in the present exemplary embodiment, the first light source  55 A and the second light source  55 B are arranged in an axisymmetric relation with the light path as a symmetric axis. 
     Moreover, the first light source  55 A and the second light source  55 B are respectively arranged at positions having a distance Y from the second platen glass  52 B. That is, the first light source  55 A and the second light source  55 B are each arranged to have the distance Y from the second platen glass  52 B and to be separated from the second platen glass  52 B (hereinafter the distance Y from the first light source  55 A and the second light source  55 B to the second platen glass  52 B is optionally referred to as a “separate distance Y”). 
     The second platen glass  52 B is affected by heat when the first light source  55 A and the second light source  55 B are lighted consecutively and the like, which might cause a crack. In addition, the first light source  55 A and the second light source  55 B might contact with the second platen glass  52 B or the first platen glass  52 A during scanning. Thus, it is preferable that the first light source  55 A and the like and the second platen glass  52 B and the like are arranged separately from each other as mentioned above. Further, the separate distance Y is preferably set at a length that may avoid the crack caused by heat generated from the second platen glass  52 B or the contact between the second platen glass  52 B and the like and the first light source  55 A and the like. 
     In order to increase a light amount at the read part A, as in the second light source  55 B shown by a broken line in the  FIG. 2B , such a configuration may be adopted in which the second light source  55 B is arranged so that a normal line, which is a normal line to the light emitting face of the second light source  55 B and extends from the center part in the width direction (hereinafter referred to as a “center normal line”) is directed to the read part A. 
     However, according to a finding by a computer simulation by the inventor, it is confirmed that, rather than the above configuration, a configuration in which the second light source  55 B is arranged so that the center normal line is directed to the parts other than the read part A increases the light amount at the read part A. In particular, it is confirmed that the light amount at the read part A is increased with a configuration in which the second light source  55 B is arranged at an inclination angle α 1  smaller than an inclination angle α 2  when the second light source  55 B is arranged so that the center normal line is directed to the read part A. In addition, it is confirmed that the light amount at the read part A is increased with a configuration in which the second light source  55 B is arranged along the second platen glass  52 B (document) rather than the second light source  55 B arranged so that the center normal line is directed to the read part A. 
     A result of the simulation will be described below in detail. 
     Here,  FIGS. 3A to 3C  are graphs in which the separate distance Y and the inclination angle α are plotted when the light amount at the read part A becomes the maximum as the separate distance Y and the inclination angle α are changed. In each of these figures, the separate distance Y and the inclination angle α, when the light amount becomes the maximum, are shown by a solid line. On the other hand, a relation between the separate distance Y and the inclination angle α when the first light source  55 A and the second light source  55 B are arranged so that the center normal line is directed to the read part A is shown by a broken line. 
     It should be noted that,  FIG. 3A  shows a result when the separate distance X is 1.5 mm,  FIG. 3B  shows a result when the separate distance X is 3.0 mm, and  FIG. 3C  shows a result when the separate distance X is 4.5 mm. In addition, the width L of the first light source  55 A and the second light source  55 B is 2 mm for each. 
     First,  FIG. 3A  will be explained. If the separate distance Y is 3 mm, for example, the inclination angle α of the first light source  55 A and the like is 22° when the first light source  55 A and the second light source  55 B (hereinafter optionally referred to as “a first light source  55 A and the like”) are arranged so that the center normal line is directed to the read part A. On the other hand, the inclination angle α of the first light source  55 A and the like is 13° when the light amount at the read part A becomes the maximum. In addition, if the separate distance Y is 7 mm, for example, the inclination angle α of the first light source  55 A and the like is 14° when the first light source  55 A and the like are arranged so that the center normal line is directed to the read part A. On the other hand, the inclination angle α of the first light source  55 A and the like is 3.4° when the light amount at the read part A becomes the maximum. 
     From the above results, it is found that, in order to maximize the light amount at the read part A, the first light source  55 A and the like should be arranged at the inclination angle α smaller than the inclination angle α of the first light source  55 A and the like arranged so that the center normal line is directed to the read part A. 
     Next,  FIG. 3B  will be explained. If the separate distance Y is 3 mm, for example, the inclination angle α of the first light source  55 A and the like is 31.7° when the first light source  55 A and the like are arranged so that the center normal line is directed to the read part A. On the other hand, the inclination angle α of the first light source  55 A and the like is 23.1° when the light amount at the read part A becomes the maximum. In addition, if the separate distance Y is 7 mm, for example, the inclination angle α of the first light source  55 A and the like is 21.3° when the first light source  55 A and the like are arranged so that the center normal line is directed to the read part A. On the other hand, the inclination angle α of the first light source  55 A and the like is 9.1° when the light amount at the read part A becomes the maximum. From the above results, it is also found that, in order to maximize the light amount at the read part A, the first light source  55 A and the like should be arranged at the inclination angle α smaller than the inclination angle α of the first light source  55 A and the like arranged so that the center normal line is directed to the read part A. 
     Further,  FIG. 3C  will be explained. If the separate distance Y is 3 mm, for example, the inclination angle α of the first light source  55 A and the like is 40° when the first light source  55 A and the like are arranged so that the center normal line is directed to the read part A. On the other hand, the inclination angle α of the first light source  55 A and the like is 34° when the light amount at the read part A becomes the maximum. In addition, if the separate distance Y is 7 mm, for example, the inclination angle α of the first light source  55 A and the like is 27.6° when the first light source  55 A and the like are arranged so that the center normal line is directed to the read part A. On the other hand, the inclination angle α of the first light source  55 A and the like is 18° when the light amount at the read part A becomes the maximum. From the above results, it is also found that, in order to maximize the light amount at the read part A, the first light source  55 A and the like should be arranged at the inclination angle α smaller than the inclination angle α of the first light source  55 A and the like arranged so that the center normal line is directed to the read part A. 
     Next,  FIGS. 4A to 4C  will be explained. Here,  FIGS. 4A to 4C  are graphs in which the separate distance Y and the inclination angle α are plotted when the light amount at the read part A becomes the maximum as the separate distance Y and the inclination angle α are changed on the condition that the width L of the first light source  55 A and the like is set at 3 mm. In each of these figures, the separate distance Y and the inclination angle α, when the light amount becomes the maximum, are shown by a solid line. On the other hand, a relation between the separate distance Y and the inclination angle α when the first light source  55 A and the like are arranged so that the center normal line is directed to the read part A is shown by a broken line. It should be noted that, similarly to  FIGS. 3A to 3C ,  FIG. 4A  shows a result when the separate distance X is 1.5 mm,  FIG. 4B  shows a result when the separate distance X is 3.0 mm, and  FIG. 4C  shows a result when the separate distance X is 4.5 mm. 
     First,  FIG. 4A  will be explained. If the separate distance Y is 3 mm, for example, the inclination angle α of the first light source  55 A and the like is 24.9° when the first light source  55 A and the like are arranged so that the center normal line is directed to the read part A. On the other hand, the inclination angle α of the first light source  55 A and the like is 14.6° when the light amount at the read part A becomes the maximum. In addition, if the separate distance Y is 7 mm, for example, the inclination angle α of the first light source  55 A and the like is 16.1° when the first light source  55 A and the like are arranged so that the center normal line is directed to the read part A. On the other hand, the inclination angle α of the first light source  55 A and the like is 3.4° when the light amount at the read part A becomes the maximum. From the above results, it is also found that, in order to maximize the light amount at the read part A, the first light source  55 A and the like should be arranged at the inclination angle α smaller than the inclination angle α of the first light source  55 A and the like arranged so that the center normal line is directed to the read part A. 
     Next,  FIG. 4B  will be explained. If the separate distance Y is 3 mm, for example, the inclination angle α of the first light source  55 A and the like is 33.5° when the first light source  55 A and the like are arranged so that the center normal line is directed to the read part A. On the other hand, the inclination angle α of the first light source  55 A and the like is 28.9° when the light amount at the read part A becomes the maximum. In addition, if the separate distance Y is 7 mm, for example, the inclination angle α of the first light source  55 A and the like is 22.7° when the first light source  55 A and the like are arranged so that the center normal line is directed to the read part A. On the other hand, the inclination angle α of the first light source  55 A and the like is 10.1° when the light amount at the read part A becomes the maximum. From the above results, it is also found that, in order to maximize the light amount at the read part A, the first light source  55 A and the like should be arranged at the inclination angle α smaller than the inclination angle α of the first light source  55 A and the like arranged so that the center normal line is directed to the read part A. 
     Further,  FIG. 4C  will be explained. If the separate distance Y is 3 mm, for example, the inclination angle α of the first light source  55 A and the like is 40.4° when the first light source  55 A and the like are arranged so that the center normal line is directed to the read part A. On the other hand, the inclination angle α of the first light source  55 A and the like is 38.3° when the light amount at the read part A becomes the maximum. In addition, if the separate distance Y is 7 mm, for example, the inclination angle α of the first light source  55 A and the like is 28.8° when the first light source  55 A and the like are arranged so that the center normal line is directed to the read part A. On the other hand, the inclination angle α of the first light source  55 A and the like is 23.1° when the light amount at the read part A becomes the maximum. From the above results, it is also found that, in order to maximize the light amount at the read part A, the first light source  55 A and the like should be arranged at the inclination angle α smaller than the inclination angle α of the first light source  55 A and the like arranged so that the center normal line is directed to the read part A. 
     As mentioned above, when the first light source  55 A and the like are arranged at the inclination angle α smaller than the inclination angle α of the first light source  55 A and the like arranged so that the center normal line is directed to the read part A, the light amount at the read part A maybe increased. Note that, if the first light source  55 A and the like are arranged at the inclination angle α smaller than the inclination angle α, an intersection (intersection position) between the center normal line of the first light source  55 A and the center normal line of the second light source  55 B is located at a part other than the read part A. Specifically, the intersection is located on the side far from the first light source  55 A and the second light source  55 B than the read part A (refer to  FIG. 2A ). Therefore, it may be recognized that the light amount at the read part A is increased if the intersection is arranged in a part other than the read part A (if the intersection is arranged on the side far from the first light source  55 A and the second light source  55 B than the read part A). 
     As a result, generation of a so-called cavity may also be reduced, for example. Here, the cavity refers to a phenomenon in which, if an image with high density is formed adjacently to the part to be read, for example, the light amount at the read part is lowered and the light amount of the light received by the CCD image sensor  59  is lowered. 
     If an image with high image density is formed adjacently to the read part, the irradiated light is absorbed by a part with high image density. The read part is irradiated with not only the light directly from the first light source  55 A and the second light source  55 B but also the light reflected at a part other than the read part. If an image with high image density is formed, light absorption occurs and the light amount of the reflected light is lowered, and thus, the light amount at the read part is lowered. In the present exemplary embodiment, since the light amount itself at the read part may be increased, even if an image with high image density is formed, the light amount at the read part may be ensured and generation of cavity may be reduced. 
     Further, if the separate distance Y in  FIG. 3A  is 3 mm, for example, a dimension H in a height direction of the first light source  55 A and the like in the present exemplary embodiment (refer to  FIG. 2A ) is approximately 0.45 mm (L×sin α=2×sin 13°). On the other hand, the dimension H is 0.75 mm (L×sin α=2×sin 22°) when the first light source  55 A and the like are arranged so that the center normal line is directed to the read part A. 
     Furthermore, if the separate distance Y in  FIG. 4A  is 3 mm, for example, the dimension H in a height direction of the first light source  55 A and the like in the present exemplary embodiment is approximately 0.76 mm (L×sin α=3×sin 14.6°). On the other hand, the dimension H is approximately 1.26 mm (L×sin α=3×sin 24.9°) when the first light source  55 A and the like are arranged so that the center normal line is directed to the read part A. 
     That is, in the arrangement configuration of the first light source  55 A in the present exemplary embodiment, the dimension H of the first light source  55 A and the like in the height direction may be made smaller than the arrangement configuration in which the first light source  55 A and the like are arranged so that the center normal line is directed to the read part A. As a result, in the configuration in the present exemplary embodiment, the light amount at the read part A may be increased and an arrangement space for the first light source  55 A and the like may be made smaller. That is, with the configuration in the present exemplary embodiment, both improvement of lighting efficiency and space saving are realizable. 
     In the above explanation, the case in which two light sources of the first light source  55 A and the second light source  55 B are used is explained. However, it is confirmed that the result similar to the above is also obtained only with either one of the light sources. That is, it is confirmed that even with either one of the light sources, the light amount at the read part A is increased as compared with the configuration in which the light source is arranged so that the center normal line is directed to the read part A. 
     In addition, in the present exemplary embodiment, the example in which the first light source  55 A and the second light source  55 B are provided in the full-rate carriage  53  is explained. However, the first light source  82   a  and the second light source  82   b  in the CIS unit  80  may also be arranged in the configuration of the present exemplary embodiment. 
     Further, the case with the separate distance Y of 3 mm or more is shown as a specific example in the above. However, it is confirmed that the result similar to the above is also obtained in the case where the separate distance Y is 0 mm or the separate distance Y exceeds 7 mm. Furthermore, the case where the width L of the first light source  55 A and the like is 2 mm or 3 mm is explained as a specific example in the above, however, it is confirmed that the result similar to the above is also obtained in the case where the width L of the first light source  55 A and the like exceeds 3 mm. 
     Moreover, in the present exemplary embodiment, the example in which the first light source  55 A and the second light source  55 B are arranged in the full-rate carriage  53  is explained. However, the first light source  55 A and the second light source  55 B exclusively used for light irradiation to transported documents may be provided on the back face of the second platen glass  52 B. Further, to the transported document, light irradiation may be applied by using the exclusive first light source  55 A and the second light source  55 B, while, to the document placed on the first platen glass  52 A, light irradiation may be applied by using the first light source  55 A and the second light source  55 B provided in the full-rate carriage  53 . In this case, the first light source  55 A and the second light source  55 B provided on the back face of the second platen glass  52 B may be arranged with the separate distance Y=0 as mentioned above. In addition, such arrangement may be made in which one side of each of the first light source  55 A and the like in the width direction is brought into contact with the second platen glass  52 B. In this case, the light amount at the read part A may further be increased. 
     The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The exemplary embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.