Patent Publication Number: US-2010110159-A1

Title: Image reading device and image forming apparatus

Description:
INCORPORATION BY REFERENCE 
     This application is based upon and claims the benefit of priority from the corresponding Japanese Patent Application No. 2008-281140 filed Oct. 31, 2008, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates to image reading devices and image forming apparatuses, and more particularly to the handling of electrical transmission cables in such devices. 
     2. Description of the Related Art 
     The present invention relates to image reading devices which reads an image of a document and to image forming apparatuses. 
     Conventionally, an image reading device, such as a scanner, typically uses a configuration wherein an image of a document that is placed on a document reading surface is read while an image reading unit is moved in a space below the document reading surface. 
     In such an image reading device, a fixed unit is positioned in a casing. The fixed unit is electrically connected to the image reading unit. The casing supports the document reading surface. The fixed unit is connected to the image reading unit by a cable. 
     The cable connects the fixed unit to the image reading unit with a part of the cable being bent so that the image reading unit can reciprocate in the space below the document reading surface. 
     When the cable connects the fixed unit to the image reading unit, with a part of the cable being bent, a force is generated by cable as it tries to straighten itself. Hence, a force is generated in a direction away from the image reading unit and is applied to the connection between the cable and the image reading unit. 
     Thus, upon long-term use, the cable can be separated from the image reading unit. 
     In light of this, it is known to provide an image reading device in which a film member is provided at a position close to the connection between the cable and the image reading unit. The film member prevents the cable from being bent. 
     Using the film member, the force that is applied to the connection between the cable and the image reading unit in the direction away from the image reading unit can be resisted. The cable can thereby be prevented from separating from the image reading unit. 
     However, the repulsive force that is generated by the cable trying to straighten itself acts as a force that pushes the image reading unit upwardly. When the image reading unit is pushed upwardly, the image reading unit may be inclined or vertically moved, and the image reading unit therefore may not move smoothly. The force necessary for moving the image reading unit may therefore have to be increased, or a fixing member for fixing the image reading unit may also be additionally necessary. 
     The bent part of the cable typically is located at a back end of the direction of reciprocation of the image reading unit with respect to the image reading unit. When the image reading unit is located in a home-position wherein the image reading unit is positioned at the most backward end, the cable is located at a position closest to the image reading unit. 
     The image reading unit receives a greater upwardly pushing force as the image reading unit is closer to the bent part of the cable. Hence, in the typical image reading device, when the image reading unit is located in the home-position, a problem, such as a need to increase the driving force for moving the image reading unit, likely may occur. 
     SUMMARY 
     The present invention provides an image reading device which reduces the upward pushing force that is applied to an image reading unit because of the repulsive force generated by a cable trying to straighten itself. 
     The present invention provides an image reading device that is capable of reducing the repelling force generated by the cable trying to straighten itself out. 
     According to an embodiment of the present invention, the image forming apparatus includes a control section designed to control the entire image forming apparatus, a display operation section designed to perform an operation based on the operation of a user, an image storage unit designed to record image data read by an image reading unit and output the read image data, an image processing unit designed to convert the image data input from the image storage unit into print-format image data and output the print-format image data based on the control instruction input from the control section, a print section designed to perform printing on a fed recording sheet based on the control instruction inputted from the control section, and an image reading device fixed to a casing. The image reading device includes the image reading unit having a home-position, a casing supporting the image reading surface such that the image reading surface defines an upper surface of the casing, reciprocating parallel to an image reading surface, and reading an image of a document that is placed on the image reading surface while being moved in a forward direction. A cable is fixed to the casing, arranged above a flat surface of the casing, and connected with the image reading unit and a fixed unit with a part of the cable being bent, the fixed unit is electrically connected with the image reading unit. A recessed part is provided that extends downwardly from the image reading unit and receives the bent part of the cable. 
     Additional features and advantages are described herein, and will be apparent from the following Detailed Description and the figures. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       In the accompanying drawings: 
         FIG. 1  is a block diagram showing a configuration of a copier including an image reading device according to an embodiment of the present invention; 
         FIG. 2  is a cross-sectional view showing the configuration of the copier including the image reading device according to an embodiment of the present invention; 
         FIG. 3  is a perspective view showing the image reading device according to an embodiment of the present invention; 
         FIG. 4  is a cross-sectional view showing the image reading device according to an embodiment of the present invention; 
         FIG. 5  is a modification of the image reading device according to an embodiment of the present invention, in particular, is a cross-sectional view showing the image reading device having a configuration in which a recessed part is defined by a plurality of walls; and 
         FIG. 6  is a modification of the image reading device according to an embodiment of the present invention, in particular, is a cross-sectional view showing the image reading device having a configuration in which a recessed part is formed of a film member. 
     
    
    
     DETAILED DESCRIPTION 
     An image reading device according to an embodiment of the present invention will now be described below with reference to the drawings. In the following drawings, the drawings have been scaled with respect to the elements to illustrate the recognizable sizes of the elements. The following description provides a situation where the image reading device according to an embodiment of the present invention is installed in a copier, which is an example of an image forming apparatus. Also, the cable that is used in the embodiment is a flexible flat cable, however, the cable may be any other cable than a flexible flat cable. 
       FIG. 1  is a functional block diagram showing a brief design of a copier S including an image reading device  2  of an embodiment.  FIG. 2  is a cross-sectional view showing the design of the copier S. 
     Referring to  FIG. 1 , the copier S includes a display operation section  1 , an image reading device  2 , an image storage unit  3 , an image processing unit  4 , a print section  5 , and a control section  6 . 
     The display operation section  1  is positioned on a front surface of the apparatus (not shown in  FIG. 2 ), as an interface which associates the copier S and a user. The display operation section  1  includes a touch panel  1   a  and an operation key  1   b . The touch panel  1   a  is a display panel having a transparent sheet pressure sensor of, for example, a resistance film type, on a display surface. The touch panel  1   a  displays information to the user and outputs an operation signal based on the operation of the user. The operation key  1   b  is an operation key (hardware key), such as a power button or a copy start button, other than an operation button displayed on the touch panel  1   a . The operation key  1   b  outputs an operation signal based on the operation of the user. 
     The image reading device  2  reads an image of a document which is automatically fed using an auto document feeder (ADF), or of a document which is placed on a document reading surface, with a line sensor, based on a control instruction input from the control section  6 , and converts the read image into a document image data. The image reading device  2  outputs the document image data. Referring to  FIG. 2 , the image reading device  2  is located at an upper part of the copier S. The image reading device  2  will be described in more detail later. 
     The image storage unit  3  is, for example, a semiconductor memory or a hard disk device. The image storage unit  3  records the document image data input from the image reading device  2 , and reads and outputs the document image data recorded therein, based on a control instruction input from the control section  6 . 
     The image processing unit  4  converts the document image data from the image storage unit  3  into print-format image data and outputs the converted image data, based on a control instruction input from the control section  6 . 
     The image processing unit  4  can convert the document image data into print-format image data by applying, as necessary, various image processing to the document image data. For example, when the image reading device  2  reads a document formed of a color image, document image data input from the image storage unit  3  to the image processing unit  4  is RGB image data corresponding to the three primary colors of light. The image processing unit  4  converts the RGB image data into, for example, YMCK image data (image data with basic colors of Y, M, C, and K representing yellow, magenta, cyan, and black), corresponding to the print format of the print section  5 . Then, the image processing unit  4  outputs the converted image data. 
     The print section  5  performs printing (image formation) on a recording sheet (printing medium) fed from a sheet cassette  7  or a sheet feed tray  8  (see  FIG. 2 ) based on a control instruction input from the control section  6 . Referring to  FIG. 2 , the print section  5  is located in a substantially center part of the copier S. 
     Referring to  FIG. 2 , the print section  5  includes a photosensitive drum  10 , an electrifier  20 , a laser scanning unit  30 , a development unit  40 , a cleaning unit  50 , an intermediate transfer unit  60 , a fixer  70 , and a toner container  80 . 
     The photosensitive drum  10  is a cylindrical member. An electrostatic latent image is formed on the surface of the photosensitive drum  10 . The photosensitive drum  10  is positioned to extend in a depth direction of  FIG. 2 . The copier S is a tandem type image forming apparatus capable of full-color printing. The copier S includes a photosensitive drum  10  for yellow, a photosensitive drum  10  for magenta, a photosensitive drum  10  for cyan, and a photosensitive drum  10  for black, corresponding to the basic colors (Y, M, C, K) of toners. The photosensitive drums  10  are positioned parallel to each other at an interval as shown in  FIG. 2 . 
     The electrifier  20  is placed opposite each of the photosensitive drums  10 . The electrifier  20  respectively faces each of the photosensitive drums  10  of the basic colors (Y, M, C, K). The electrifier  20  electrifies the circumferential surface of the photosensitive drum  10 . 
     The laser scanning unit  30  is located below the photosensitive drum  10 . The laser scanning unit  30  transmits a laser light to irradiate the photosensitive drum  10  with the laser light, and forms an electrostatic latent image on a surface of the photosensitive drum  10 . 
     The development unit  40  includes a development roller  41  which develops an image based on the electrostatic latent image formed on the circumferential surface of the photosensitive drum  10  by supplying the circumferential surface of the photosensitive drum  10  with a toner. A development unit  40  is provided for each of the photosensitive drums  10 . 
     The cleaning unit  50  includes a rubbing roller  51  which removes toner remaining on the photosensitive drum  10  after the image is transferred from the photosensitive drum  10  to the intermediate transfer unit  60 . The cleaning unit  50  is located opposite each of the photosensitive drums  10 . 
     The intermediate transfer unit  60  is positioned above the photosensitive drums  10 . The intermediate transfer unit  60  includes an intermediate transfer belt  61  on which images developed by the photosensitive drums  10  are transferred, a driving roller  62  for rotating the intermediate transfer belt  61 , a tension roller  63  for applying a tensile force to the intermediate transfer belt  61 , a driven roller  64  which is rotated by the intermediate transfer belt  61 , a primary transfer roller  65  for transferring the toner on the photosensitive drum  10  to the intermediate transfer belt  61 , and a secondary transfer roller  66  for transferring toner on the intermediate transfer belt  61  to a recording sheet. 
     The images developed by the photosensitive drums  10  are temporarily superposed on one another on the intermediate transfer belt  61  of the intermediate transfer unit  60 , and then collectively transferred onto a recording sheet. That is, the intermediate transfer unit  60  transfers the toner on the photosensitive drums  10  onto the recording sheet. 
     The fixer  70  fixes the toner transferred by the intermediate transfer unit  60  onto the recording sheet by applying heat or pressure to the toner. The fixer  70  is located in the feeding path of the recording sheet. 
     The toner container  80  contains the toner that is supplied to the development unit  40 . The toner container  80  is located above the intermediate transfer unit  60 . A toner container  80  is provided for each of the development units  40 . 
     A sheet feed roller  90  is provided at a lower part of the apparatus. The sheet feed roller  90  supplies the print section  5  with a recording sheet that is fed from the sheet cassette  7  or the sheet feed tray  8 . 
     Referring back to  FIG. 1 , the control section  6  controls the entire copier S, and is electrically connected with the display operation section  1 , the image reading device  2 , the image storage unit  3 , the image processing unit  4 , and the print section  5 . 
     In the copier S having the above-described design, the image data of the document set at the image reading device  2  is read, and the read image data is recorded in the image storage unit  3 , based on operation inputted using the display operation section  1  by the user, under the control of the control section  6 . The image processing unit  4  converts the image data recorded in the image storage unit  3  into the print-format image data, and inputs the converted image data to the print section  5 . 
     The print section  5  performs image formation on a printing sheet corresponding to the print-format image data input from the image processing unit  4 . Then, the printing sheet, with the image printed thereon, is ejected from the copier S, as printed matter. 
     Next, an embodiment of the image reading device  2  will be described in more detail. 
       FIG. 3  is an enlarged cross-sectional view showing the image reading device  2 .  FIG. 4  is a perspective view showing the image reading device  2 . Referring to the drawings, the image reading device  2  includes a document reading surface  21 , an image reading unit  22 , a fixed unit  23 , a flexible flat cable  24  (cable), and a moving unit  25 . 
     A document is placed on the document reading surface  21 . The document reading surface  21  is supported by a casing  26  of the image reading device  2  such that the document reading surface  21  defines an upper surface of the image reading device  2 . 
     The image reading unit  22  reads the image on the document placed on the document reading unit  22 . The image reading unit  22  includes the above-mentioned line sensor, a light source, and a carriage on which components of the line sensor and the light source are mounted. 
     In the space below the document reading surface  21 , the moving unit  25  causes the image reading unit  22  to reciprocate, parallel to the document reading surface  21 . The image reading unit  22  reads the image on the document while the image reading unit  22  moves in a forward direction of reciprocation, and outputs the read image as document image data. 
     The fixed unit  23  is fixed to the casing  26  of the moving members composed of the image reading unit  22  and the casing  26 . In an embodiment, the fixed unit  23  is directly fixed to the casing  26 . 
     The fixed unit  23  includes, for example, a processing unit for performing predetermined processing for the document image data input from the image reading unit  22 , and a power source unit for feeding power to the image reading unit  22 . The fixed unit  23  is located at a position at a forward direction side with respect to the image reading unit  22 . 
     The flexible flat cable  24  is located above a flat surface  26   a , which is a bottom part of the casing  26 , and connects the image reading unit  22  with the fixed unit  23 . A part of the flexible flat cable  24  is bent. 
     Using the flexible flat cable  24 , the image reading unit  22  is electrically connected to the fixed unit  23 . 
     The moving unit  25  causes the image reading unit  22  to reciprocate. The moving unit  25  includes a guide shaft  25   a  provided above the flat surface  26   a  that extends in a direction of reciprocation of the image reading unit  22 , a slider  25   b  slidably supported by the guide shaft  25   a  and fixed to the image reading unit  22 , a motor  25   c  that functions as a drive source, and a pulley  25   d  for transmitting torque of the motor  25   c  to the slider  25   b.    
     The image reading device  2 , in an embodiment, has a recessed part  27  at a backward side of the image reading unit  22  when it is in the home-position. The recessed part  27  stores the bent part  24   a  of the flexible flat cable  24 . 
     The recessed part  27  extends downwardly to a lower position than the portion of the flat surface  26   a  of the casing  26  where the flexible flat cable  24  is located. When the image reading unit  22  is in the home-position, the recessed part  27  stores the bent part  24   a  of the flexible flat cable  24 . 
     In the recessed part  27 , a pair of opposing side walls  27   a  (guide walls) are separated from each other by a slightly larger distance than the width of the flexible flat cable  24  so that the side walls  27   a  function as a guide for guiding the flexible flat cable  24  into the recessed part  27 . 
     Further, the recessed part  27  includes a bottom part  27   b , an inclined part  27   c  that inclines from a forward direction side to the bottom part  27   b , and a curved part  27   d  that curves from the bottom part  27   b  toward a connection position A between the flexible flat cable  24  and the image reading unit  22  in the home-position. 
     The depth of the recessed part  27  is such that the curvature of the curved part  27   d  corresponds to the curvature of the bent part  24   a  of the flexible flat cable  24  when the image reading unit  22  is located in the home-position. 
     In an embodiment of the image reading device  2 , wherein a document is placed on the document reading surface  21 , the image reading unit  22  reads an image of the document while the moving unit  22  causes the image reading unit  22  to reciprocate in a forward direction. When the image reading is completed, the image reading unit  22  is moved by the moving unit  25  in a backward direction, and returns to the home-position. 
     Herein, in an embodiment of the image reading device  2 , the recessed part  27  is formed at a backward end of the home-position. When the moving unit  25  is located in the home-position, the bent part  24   a  of the flexible flat cable  24  is received in the recessed part  27 . 
     The recessed part  27  extends downwardly with respect to the portion of the flat surface  26   a  of the casing  26  wherein the flexible flat cable  24  is located. Hence, compare to the situation where there is no recessed part  27 , the curvature of the bent part  24   a  of the flexible flat cable  24  is small. Thus, the repulsive force generated by the flexible flat cable  24  can be reduced. 
     The flexible flat cable  24  is guided into the recessed part  27  by the side walls  27   a  of the recessed part  27  when the image reading unit  22  is moved in a backward direction. 
     Further, when the bent part  24   a  of the flexible flat cable  24  is received in the recessed part  27 , the flexible flat cable  24  extends along the inclined part  27   c  and hence is gradually bent toward the bottom part  27   b  of the recessed part  27 . Then, the bent part  24   a  of the flexible flat cable  24  is held by the curved part  27   d.    
     With the image reading device  2  of the above-described embodiment, the recessed part  27  formed at the backward end of the image reading unit  22 , when it is in the home-position, is bent downward at that position of the flat surface  26   a  at which the flexible flat cable  24  is located. 
     When the image reading unit  22  is located in the home-position and the bent part  24   a  of the flexible flat cable  24  is received in the recessed part  27 , the curvature of the bent part  24   a  is smaller than that of a bent part  24   a  if there were not any recessed part  27 . 
     Accordingly, the repulsive force that is generated the flexible flat cable  24  trying to straighten itself becomes smaller than that of a typical image reading device. 
     Using the image reading device  2  of this embodiment, the upward pushing force that is applied to the image reading unit  22 , due to the repulsive force trying to straighten the flexible flat cable  24 , can be reduced. 
     Also, in the image reading device  2  of this embodiment, the recessed part  27  includes opposite side walls  27   a  which are separated from each other by a distance corresponding to the width of the flexible flat cable  24 , and which guides the flexible flat cable  24 . 
     With the design, when the image reading unit  22  is moved in a backward direction to its home-position, the flexible flat cable  24  can be reliably guided into the recessed part  27 . 
     In addition, in the image reading device  2  of this embodiment, the recessed part  27  includes an inclined part  27   c  and a curved part  27   d . The depth of the recessed part  27  is determined such that the curvature of the curved part  27   d  corresponds to the curvature of the bent part  24   a  of the flexible flat cable  24  when the image reading unit  22  is located in the home-position. 
     Accordingly, when the bent part  24   a  of the flexible flat cable  24  is housed in the recessed part  27 , the flexible flat cable  24  extends along the inclined part  27   c  and gradually bends to the bottom part  27   b  of the recessed part  27 . Further, the bent part  24   a  is held by the curved part  27   d.    
     Thus, the force applied to the flexible flat cable  24  can be minimized, and the bent part  24   a  can be stored in the recessed part  27 . 
     A preferred embodiment of the present invention has been described above in detail with reference to the drawings, however, the invention is not limited to that of the embodiment, and may be modified. 
     For example, the curved part  27   d  of the recessed part  27  in the above-described embodiment may not be provided. Referring to  FIG. 5 , a recessed part  27  may be formed by a plurality of flat walls. 
     With this design, the recessed part  27  has a larger volume than the volume of the recessed part  27  having the curved part  27   d . Hence, when the operation of the moving unit  25  varies and the movement position of the flexible flat cable  24  is shifted slightly, the flexible flat cable  24  can be easily stored. 
     Alternatively, for example, a recessed part  27  may be formed by a flexible film member. One end of the film member may be fixed whereas another end of the film member may be slidable relative to the casing, so that the depth of the recessed part  27  is varied. 
     With this design, the depth of the recessed part  27  can be determined depending on the type of image reading device. A large space can be provided below the recessed part  27 . Accordingly, a recording sheet can be easily taken out. 
     For example, in the above-described embodiment, the copier has been described as an example of an image forming apparatus to which the image reading device of the present invention is installed. 
     However, the present invention does not have to be installed in a copier, and may be installed in an image forming apparatus, such as a multifunction apparatus, a printer, a facsimile, and the like. 
     According to another embodiment, in the above-described design, the recessed part may have guide walls separated from each other by a distance corresponding to a width of the cable and guiding the cable. 
     According to still another embodiment, in the above-described design, the recessed part may include a bottom part, an inclined part that inclines from a forward side to a bottom part, and a curved part that curves from the bottom toward a connection position between the cable and the image reading unit in a home-position. 
     According to yet another embodiment, in the above-described design, the depth of the recessed part may be determined such that the curvature of the curved part corresponds to the curvature of the bent part of the cable when the image reading unit is located at the home-position. 
     According to another embodiment, an image forming apparatus which performs image formation includes the image reading device of the above-described design, the image reading device reading an image of a document. 
     It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.