Abstract:
A sheet transport apparatus including two or more covers is described. The two or more covers are disposed relative to a sheet transport path. In one example, the two covers include two stacked covers that are movable relative to each other. In another example, the two covers include two side-by-side covers in which one pivots, permitting movement of the other side-by-side cover.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from Japanese Patent Application No. 2011-086226, filed on Apr. 8, 2011, the entire subject matter of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    Aspect of the present invention relate to a sheet transport apparatus. 
         [0004]    2. Description of the Related Art 
         [0005]    A known printer, facsimile, scanner, and multifunction device includes a sheet transport mechanism that transports a sheet along a predetermined transport path. Such an apparatus reads an image of a sheet or forms an image on a sheet while transporting the sheet along the transport path. 
         [0006]    This example of a facsimile apparatus describes a sheet transport apparatus including such a transport mechanism. The facsimile apparatus includes a transparent plate portion that is made of a transparent plastic, such as an acrylic resin. The transparent plate portion is removably attached to a surface of the apparatus, so that the appearance of the apparatus can be customized. 
         [0007]    A user can place a decoration such as patterned paper between the transparent plate portion and a surface of the facsimile apparatus. The pattern of the decoration, which is visible through the transparent plate portion, enhances the appearance of the facsimile apparatus. With the described facsimile apparatus, a user can change the pattern by removing the screws and changing the decoration placed between the transparent plate portion and the surface of the apparatus, thereby customizing the appearance of the apparatus. 
         [0008]    However, in the case of the described facsimile apparatus, the user has to remove the screws from the four corners of the transparent plate portion to remove the transparent plate portion from the surface of the apparatus. Therefore, the user has to perform a complex operation of removing and fastening the screws in order to remove and reattach the transparent plate portion. 
         [0009]    Against such a background, it is worth considering to simplify a structure for attaching and removing a cover member, such as the transparent plate portion. A simplified structure for a cover member would allow a user to attach the cover member to the surface of the apparatus with an easy operation. In this case, however, the cover member may come off the surface of the apparatus if the user unintentionally contacts the cover member when the cover member is not to be removed (for example, during a normal use of the apparatus). In such a case, the user would need to reattach the cover member to the surface of the apparatus. 
       SUMMARY 
       [0010]    Illustrative aspects of the invention may provide a sheet transport apparatus that allows a cover (that may hold a decorative sheet) to be removably attached to a surface of the apparatus by using a structure that is simple and that prevents unintentional removal of the cover. 
         [0011]    Aspects of the present invention provide a sheet transport apparatus including two or move covers disposed relative to a sheet transport path. In one example, the two covers include two stacked covers that are movable relative to each other. In another example, the two covers include two side-by-side covers in which one pivots, permitting movement of the other side-by-side cover. In a third example, the stacked covers and the side-by-side covers are used together in relation to the sheet transport path. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is an external perspective view of a multifunction device; 
           [0013]      FIG. 2  is an external view of the multifunction device when a cover tray is rotated; 
           [0014]      FIG. 3  is an external view of the multifunction device when a first stacked cover is open and the cover tray is rotated to a use position; 
           [0015]      FIG. 4  is a sectional view of a sheet cover; 
           [0016]      FIG. 5  is an external view of the first stacked cover; 
           [0017]      FIG. 6  is an external view of a first top cover; 
           [0018]      FIG. 7  is a sectional view of the vicinity of the first top cover when the first stacked cover is closed; 
           [0019]      FIG. 8  is a sectional view of the vicinity of the first top cover when the first stacked cover is open; 
           [0020]      FIG. 9  is an external view of a second top cover; 
           [0021]      FIG. 10  is a sectional view of the vicinity of the second top cover when the cover tray is at the closed position; and 
           [0022]      FIG. 11  is a sectional view of the vicinity of the second top cover when the cover tray is at the open position. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Hereinafter, an embodiment of the present invention will be described. 
         [0024]    An illustrative embodiment will be described in detail with reference to the accompanying drawings. A sheet transport apparatus according to illustrative aspects of invention applies to a sheet transport unit  60  in multifunction device  1  as shown in the figures. 
         [0025]    In the following description, in order to clearly describe the positional relationship of parts of the multifunction device  1 , the directions of up, down, left, right, front, and rear indicated in the figures will be used. 
         [0026]    First, the overall structure of the multifunction device  1  according to the present embodiment will be described with reference to the drawings. 
         [0027]    As illustrated in  FIG. 1 , the multifunction device  1  includes a main housing  10  and a sheet cover  25 . The main housing  10  contains various components for carrying out the functions of the multifunction device  1  (such as a scanner function, a facsimile function, and a printer function). 
         [0028]    The main housing  10  has an operation panel  11  and a liquid crystal display  13  on the upper front side thereof. The operation panel  11  has operation keys. The liquid crystal display  13  displays various information. The operation panel  11  is used to input instructions to the multifunction device  1 . A sheet feed cassette  12  is removably attached into the front side of the main housing  10 . The sheet feed cassette  12  contains a stack of sheets, which are recording media. 
         [0029]    As illustrated in  FIGS. 1 to 4 , the main housing  10  has a scanner unit  20  on the upper side thereof. The scanner unit  20  includes a contact glass  21 , an image sensor  22 , a slide shaft, and a motor. The contact glass  21  functions as a document placing table (see  FIG. 4 ). The contact glass  21 , which is a so-called “platen glass”, has a rectangular shape that is slightly larger than an A4 sheet, the long side of which extends in the left-right direction of the main housing  10 . 
         [0030]    The image sensor  22 , which is a so-called contact image sensor (CIS), reads an image of a document sheet on the contact glass  21 . The image sensor  22  has a readable range having a length in the main scanning direction (i.e., the front-rear direction of the main housing  10 ) that corresponds to the length of a short side of an A4 sheet. The image sensor  22  is supported so as to be slidable within a certain range (corresponding to the length of an A4 sheet) along a slide shaft that extends in the left-right direction of the main housing  10 . The multifunction device  1  reads an image of a document sheet placed on the contact glass  21  while sliding the image sensor  22  along the slide shaft by using a motor controlled by a control unit. 
         [0031]    The control unit includes a CPU, a ROM, and a RAM, and serves as a main controller of the multifunction device  1 . The control unit is connected to the operation panel  11 . Thus, the control unit is capable of performing an operation required by a user on the basis of an input by the user through the operation panel  11 . Moreover, the control unit is capable of displaying various information on the liquid crystal display  13  on the basis of a calculation result or an input by a user through the operation panel  11 . 
         [0032]    A facsimile unit faxes an image of a document sheet read by the scanner unit  20  to a recipient designated by a user through a network. The facsimile unit is also capable of receiving data (facsimile data) through the network. The control unit controls an image forming unit to print the received facsimile data on a sheet contained in the sheet feed cassette  12 . 
         [0033]    An image forming unit prints input image data on a sheet contained in the sheet feed cassette  12  under the control by the control unit. A copy function of the multifunction device  1  is carried out by controlling the image forming unit on the basis of image data read by the scanner unit  20 . A printer function of the multifunction device  1  is carried out by controlling the image forming unit on the basis of print data that is input through a network. 
         [0034]    The sheet cover  25  is openable and closable around the back end of the upper surface of the main housing  10 . When the sheet cover  25  is closed, the sheet cover  25  covers the upper surface of the main housing  10  (i.e., the contact glass  21 ) (see  FIG. 4 ). Therefore, when the sheet cover  25  is closed, the sheet cover  25  is capable of fixing a document sheet that is set on the contact glass  21  in place. 
         [0035]    As illustrated in  FIGS. 1 to 4  and other figures, the sheet cover  25  includes a cover housing  26  including a second side-by-side cover  30 , a sheet guide surface  35 , a unit body  40 , and a first stacked cover  45 . The sheet transport unit  60  (a so-called auto document feeder (ADF)) is disposed on the left side of the sheet cover  25 . 
         [0036]    As illustrated in  FIG. 1 , the second side-by-side cover  30  is disposed in the middle of the upper surface of the sheet cover  25 . The second side-by-side cover  30  is pivotable about an axis of a tray shaft  31  disposed at an end (the right end) of the second side-by-side cover  30  (see  FIGS. 2 to 4 ). It is appreciated that tray shaft  31  may be replaced with projections from or extending into second side-by-side cover  30  such that it is pivotable with respect to scanner  20 . As illustrated in  FIG. 1 , when the second side-by-side cover  30  is in a closed state (hereinafter, the position of the second side-by-side cover  30  in this state will be referred to as a closed position), the second side-by-side cover  30  forms the upper surface of the sheet cover  25  and is an almost the same plane with a second stacked cover  70  and a first side-by-side cover  80 , which will be described below. 
         [0037]    A surface of the second side-by-side cover  30  that forms the outer surface of the sheet cover  25  when the second side-by-side cover  30  is at the closed position will be referred to as a “first surface” of the second side-by-side cover  30 , and a surface opposite to the first surface (inner surface of the second side-by-side cover  30  when the second side-by-side cover  30  is at the closed position) will be referred to as a “second surface” of the second side-by-side cover  30 . 
         [0038]    When the second side-by-side cover  30  is rotated by a predetermined amount, the second side-by-side cover  30  is positioned at a predetermined use position (see  FIGS. 3 and 4 ). When the second side-by-side cover  30  is at the use position, the second surface of the second side-by-side cover  30  faces up and is inclined downward toward the sheet transport unit  60  (see  FIGS. 2 and 3 ). Therefore, when the second side-by-side cover  30  is at the use position, a stack of document sheets can be placed on the second surface of the second side-by-side cover  30 . That is, when the second side-by-side cover  30  is at the use position, the second side-by-side cover  30  functions as a feed tray. 
         [0039]    When the second side-by-side cover  30  is at the closed position, the sheet guide surface  35  and a pair of sheet guide members  36  are positioned below the second side-by-side cover  30  (see  FIGS. 1 to 4 ). Therefore, when the second side-by-side cover  30  is rotated by a predetermined amount to the predetermined use position (see  FIGS. 3 and 4 ), the sheet guide members  36  and the sheet guide surface  35  are exposed to the outside. 
         [0040]    The sheet guide surface  35  is a flat surface formed along an end portion of a sheet transport path R (see  FIG. 4 ) that is formed in an area of the unit body  40  corresponding to a lower portion of the sheet transport unit  60 . The sheet guide surface  35  is continuous with an edge of the second side-by-side cover  30  when the second side-by-side cover  30  is at the use position. Thus, the sheet guide surface  35  guides a document sheet placed on the second surface of the second side-by-side cover  30  to the sheet transport path R in the sheet transport unit  60 . 
         [0041]    The sheet guide members  36  are slidable over the sheet guide surface  35  in the front-rear direction. The sheet guide members  36  are configured to be slidable in directions opposite to each other by using a link mechanism (not shown). Therefore, by operating only one of the sheet guide members, the sheet guide members  36  can be slid in directions in which the sheet guide members  36  are made closer to or separated from each other, whereby the distance between the sheet guide members  36  can be changed. Thus, in the multifunction device  1 , a document sheet can be aligned with the sheet guide members  36  by operating the sheet guide members  36 , whereby the document sheet is prevented from being inclined with respect to the transport direction. 
         [0042]    The sheet guide members  36  each include a partition plate  36 A. The partition plate  36 A is disposed above the sheet guide surface  35  with a certain gap therebetween. 
         [0043]    As illustrated in  FIGS. 3 and 4 , a recess  37  is formed below the tray shaft  31  of the second side-by-side cover  30 . The recess  37  forms a space through which an end portion of the second side-by-side cover  30  adjacent to the tray shaft  31  passes when the second side-by-side cover  30  rotates. Therefore, the recess  37  allows the second side-by-side cover  30  to smoothly rotate around the tray shaft  31 . Moreover, the recess  37  allows the upper surface of the sheet guide surface  35  to be near the shaft of the second side-by-side cover  30  in the height direction, whereby the height of the sheet cover  25  can be reduced. 
         [0044]    As described above, a main part of the sheet transport unit  60  (a transport mechanism for transporting a document sheet) is disposed on the left side of the sheet cover  25 . The sheet transport unit  60  successively feeds document sheets placed on the second surface of the second side-by-side cover  30  and the sheet guide surface  35 , separates the document sheets into individual document sheets, and transports the document sheet along a predetermined sheet transport path R (see  FIG. 4 ) formed in the main part of the sheet transport unit  60 . The multifunction device  1  is capable of reading an image of the document sheet using the scanner unit  20  and the like while the document sheet is transported by the sheet transport unit  60 . 
         [0045]    The sheet transport path R, which is substantially U-shaped, extends in the left-right direction of the sheet transport unit  60  from the second surface of the second side-by-side cover  30  and the sheet guide surface  35  to the upper surfaces of the partition plates  36 A of the sheet guide members  36  (see  FIG. 4 ). In the present embodiment, a direction extending from the upper surface of the sheet guide surface  35  along the sheet transport path R toward the partition plates  36 A will be referred to as the transport direction of a document sheet. The width direction of a document sheet that is transported along the sheet transport path R (i.e., the front-rear direction of the sheet transport unit  60 ) will be referred to as the width direction of the document sheet. 
         [0046]    As illustrated in  FIGS. 3 and 4 , the unit body  40  and the first stacked cover  45  are formed on the left side of the sheet cover  25 . As described above, the unit body  40  is a part of the cover housing  26  including the main mechanism of the sheet transport unit  60  (such as a pair of transport rollers  61  and a transport driving roller  62 , which will be described below). That is, the unit body  40  is the main part of the sheet transport unit  60 . A part of the sheet transport path R is formed in the unit body  40  so as to connect the vicinity of the sheet guide surface  35  to the upper surface of the unit body  40  (see  FIG. 4 ). 
         [0047]    The first stacked cover  45  is supported so as to be rotatable around an axis. The axis may be provided by shaft  49 .  FIG. 4  shows shaft  49  positioned at the left end of the unit body  40 , so that the first stacked cover  45  is openable and closable relative to the upper surface of the unit body  40  (see  FIGS. 1 to 8 ). It is appreciated that shaft  49  may be replaced with projections from or extending into first stacked cover  45  such that it is pivotable with respect to scanner  20 . The inner surface (lower surface) of the first stacked cover  45  and the upper surface of the unit body  40  cooperatively form a part of the sheet transport path R. Therefore, a part of the sheet transport path R between the upper surface of the unit body  40  and the first stacked cover  45  is connected to a part of the sheet transport path R in the unit body  40 , and the sheet transport path R extends toward the partition plates  36 A of the sheet guide members  36 . 
         [0048]    The second stacked cover  70  and a decorative sheet D are removably attached to the upper surface of the first stacked cover  45  (a first top cover attachment surface  46  described below). This will be described below in detail. 
         [0049]    As illustrated in  FIG. 4 , a second top cover attachment surface  50  is formed on the right side of the sheet cover  25 . The second top cover attachment surface  50  is a surface that forms the upper surface of the cover housing  26  on the right side of the sheet cover  25  and to which the first side-by-side cover  80  and the decorative sheet D (described below) are removably attached. The structure of the second top cover attachment surface  50  will be described below in detail. 
         [0050]    Referring to  FIG. 4 , the structure of the sheet transport unit  60  of the multifunction device  1  will be described in detail. The sheet transport unit  60  includes the pair of transport rollers  61 , the transport driving roller  62 , a sheet pressing member  63 , and a transport driven roller  64 . As described above, the sheet transport unit  60  transports a document sheet along a predetermined sheet transport path R (see  FIG. 4 ). 
         [0051]    As illustrated in  FIGS. 4 ,  7 , and  8 , the pair of transport rollers  61  are disposed so as to face each other with the sheet transport path R therebetween. The pair of transport rollers  61  are controlled by the control unit and rotate while nipping a document sheet, which is located on the sheet transport path R, therebetween. The transport driving roller  62  is pivotably disposed along the upper surface of the unit body  40 , and transports a document sheet, which is transported in the sheet transport path R, which extends along the upper surface of the unit body  40 , toward the upper surface of the partition plates  36 A of the sheet guide members  36 . 
         [0052]    The sheet pressing member  63  is disposed upstream of the pair of transport rollers  61  in the transport direction, and presses a document sheet on the sheet transport path R against the contact glass  21 . In the multifunction device  1 , the image sensor  22  is positioned below the sheet pressing member  63  when the sheet transport unit  60  reads an image of a document sheet. Thus, the multifunction device  1  is capable of reading an image of a document sheet through the contact glass  21  by using the image sensor  22  while the document sheet is passing below the sheet pressing member  63 . At this time, because the sheet pressing member  63  presses the document sheet against the contact glass  21 , the image can be read with a high precision. 
         [0053]    The transport driven roller  64  is pivotably supported on the inner surface of the first stacked cover  45 . The transport driven roller  64  faces the transport driving roller  62  with the sheet transport path R therebetween when the first stacked cover  45  is closed relative to the upper surface of the unit body  40 . Therefore, the transport driven roller  64  and the transport driving roller  62  are capable of cooperatively transporting a document sheet, which is transported along the sheet transport path R, toward the upper surfaces of the partition plates  36 A of the sheet guide members  36 . 
         [0054]    Next, the structure of the first stacked cover  45  of the multifunction device  1  according to the present embodiment will be described in detail with reference to the drawings. As described above, the first stacked cover  45  is attached to the left side of the sheet cover  25  so as to be openable and closable relative to the unit body  40 . As illustrated in  FIG. 5 , the first stacked cover  45  includes the first top cover attachment surface  46  and the shaft  49 . The shaft  49  linearly extends at the left end of the first stacked cover  45  in the front-rear direction, and pivotably supports the first stacked cover  45  so that the first stacked cover  45  can be opened and closed relative to the unit body  40 . 
         [0055]    The first top cover attachment surface  46  is a flat portion that forms the upper surface of a left side portion of the cover housing  26 . First slide holes  47  and first engagement holes  48  are formed in the first top cover attachment surface  46 . The second stacked cover  70  (described below) with a decorative sheet D is removably attached to the first top cover attachment surface  46 . 
         [0056]    The first slide holes  47  are substantially rectangular holes formed in the right-hand corners of the first top cover attachment surface  46 . When the second stacked cover  70  is attached to the first top cover attachment surface  46 , first protruding pieces  73  (described below) formed on the second stacked cover  70  are slidably inserted into the first slide holes  47  (see  FIGS. 7 and 8 ). The first slide holes  47  each have an inclined surface that extends from the left edge thereof and that is inclined toward to the back surface (a surface facing the unit body  40 ). When attaching and removing the second stacked cover  70 , the first protruding pieces  73  are inserted into the first slide holes  47  while being slid along the inclined surfaces. 
         [0057]    First engagement holes  48  are formed in the left-hand corners of the first top cover attachment surface  46 . When attaching the second stacked cover  70 , the first engagement holes  48  engage with first slide engagement pieces  74 , which are formed on the second stacked cover  70  as described below, and removably hold the second stacked cover  70  on the first top cover attachment surface  46  (see  FIGS. 7 and 8 ). Each of the first engagement holes  48 , which is formed in the first top cover attachment surface  46 , includes an engageable piece formed on a lower surface thereof and a hole portion formed in the lower side thereof. The hole portions are formed so that the first slide engagement pieces  74  can be slid therein in the left-right direction. 
         [0058]    Next, the structure of the second stacked cover  70  of the multifunction device  1  according to the present embodiment will be described in detail with reference to the drawings. The second stacked cover  70  is made of a transparent resin, and is removably attached to the upper surface of the first stacked cover  45  (the first top cover attachment surface  46 ). The second stacked cover  70  includes a flat panel portion  71 , a side panel portion  72 , the first protruding pieces  73 , and the first slide engagement pieces  74 . A decorative sheet D having a predetermined pattern can be held between the second stacked cover  70  and the first top cover attachment surface  46 . 
         [0059]    The flat panel portion  71  has a shape that is substantially the same as that of the first top cover attachment surface  46 . The decorative sheet D is held along the flat panel portion  71  by the first protruding pieces  73  and the first slide engagement pieces  74 . The side panel portion  72  extends in a left downward direction from the left edge of the flat panel portion  71 . 
         [0060]    The first protruding pieces  73  protrude downward from the right-hand corners of the flat panel portion  71 . When attaching the second stacked cover  70 , the first protruding pieces  73  are slid into the first slide holes  47  along long sides of the first slide holes  47 . The first protruding pieces  73  and the first slide holes  47 , which are formed in the first top cover attachment surface  46 , cooperatively serve to removably hold the second stacked cover  70  at a predetermined position of the first top cover attachment surface  46 . When the second stacked cover  70  is attached to the first top cover attachment surface  46 , the first protruding pieces  73  protrude to predetermined positions that are below the first top cover attachment surface  46  of the first stacked cover  45  (see  FIGS. 7 and 8 ). 
         [0061]    The first slide engagement pieces  74  are formed at ends of the side panel portion  72  in the front-back direction. The first slide engagement pieces  74  extend rightward from the side panel portion  72  along the flat panel portion  71 . When attaching the second stacked cover  70 , the first slide engagement pieces  74  enter the first engagement holes  48  formed in the first stacked cover  45  as the second stacked cover  70  slides. The first slide engagement pieces  74  have projections at end portions of the upper surfaces thereof. When the second stacked cover  70  is moved to a predetermined position, the projections are fitted into the engagement recesses in the engageable pieces of the first engagement holes  48 . Therefore, the second stacked cover  70  is removably attached to the first top cover attachment surface  46  using the first slide engagement pieces  74  and the first engagement holes  48 . 
         [0062]    The first protruding pieces  73  and the first slide engagement pieces  74  respectively have slits that extend along the flat panel portion  71 . When edges of the decorative sheet D are inserted into the slits, the slits serve to hold the decorative sheet D along the flat panel portion  71  (see  FIGS. 7 ,  8 , etc.). Therefore, the pattern of the decorative sheet D can be seen through the second stacked cover  70 , which is made of a transparent resin. The decorative sheet D can be replaced with a decorative sheet having a different pattern by removing the second stacked cover  70  from the first top cover attachment surface  46  of the first stacked cover  45 . 
         [0063]    Next, an operation of attaching the second stacked cover  70  to the first top cover attachment surface  46  of the first stacked cover  45  and an operation of removing the second stacked cover  70  from the first top cover attachment surface  46  will be described in detail with reference to the drawings. First, a case where the first stacked cover  45  is closed when the second stacked cover  70  is attached to the first top cover attachment surface  46  will be described. 
         [0064]    As described above, the first slide holes  47 , the first protruding pieces  73 , the first engagement holes  48 , and the first slide engagement pieces  74  cooperatively serve to removably attach the second stacked cover  70  to the first top cover attachment surface  46 . As illustrated in  FIGS. 7 and 8 , when removing the second stacked cover  70  from the first top cover attachment surface  46 , a user slides the second stacked cover  70  toward the shaft  49  (toward the left of the multifunction device  1 ). 
         [0065]    The direction in which the second stacked cover  70  is slid to remove the second stacked cover  70  (a direction toward the left of the multifunction device  1 ) will be referred to as a “first top cover removal direction” and the opposite direction will be referred to as a “first top cover attachment direction”. 
         [0066]    The unit body  40  according to the present embodiment includes slide restricting portions  41  at two positions at the right end of the unit body  40 . The distance between the shaft  49  and each of the slide restricting portions  41  is slightly smaller than the distance between the shaft  49  and the right end of the first stacked cover  45 . Therefore, if the first stacked cover  45  is closed when the second stacked cover  70  is attached to the first top cover attachment surface  46 , the first protruding pieces  73  of the second stacked cover  70  are located in the vicinity of the slide restricting portions  41  of the unit body  40  of the first stacked cover  45  in a state in which the first protruding pieces  73  extend through the first slide holes  47 . That is, as illustrated in  FIG. 7 , the slide restricting portions  41  are disposed on the shaft  49  side (on the left side) of the first protruding pieces  73 . 
         [0067]    The slide restricting portions  41  extend to a height that is slightly smaller than that of the first top cover attachment surface  46 . That is, if the first stacked cover  45  is closed when the second stacked cover  70  is attached to the first top cover attachment surface  46 , the upper ends of the slide restricting portions  41  are located above the lower ends of the first protruding pieces  73  of the second stacked cover  70  that extend through the first slide holes  47 . Therefore, if the second stacked cover  70  is slid in the first top cover removal direction when the second stacked cover  70  is attached to the first top cover attachment surface  46  and the first stacked cover  45  is closed, the first protruding pieces  73  of the second stacked cover  70  contact the right side surfaces of the slide restricting portions  41 . That is, the sliding amount of the second stacked cover  70  is restricted by the slide restricting portions  41 , so that the second stacked cover  70  is prevented from being moved by an amount that may release the engagement between the first slide engagement pieces  74  and the first engagement holes  48 . Thus, when the first stacked cover  45  is closed, a user cannot remove the second stacked cover  70  from the first top cover attachment surface  46  (see  FIG. 7 ). 
         [0068]    Next, a case where the first stacked cover  45  is opened when the second stacked cover  70  is attached to the first top cover attachment surface  46  will be described. As illustrated in  FIG. 8 , when the first stacked cover  45  is opened, the first protruding pieces  73  move upward as the first stacked cover  45  rotates and become separated from the slide restricting portions  41  of the unit body  40 . Therefore, when the first stacked cover  45  is opened, the slide restraining portions  41  are not located on a path along which the first protruding pieces  73  move when the second stacked cover  70  is slid in the first top cover removal direction, so that the sliding amount of the second stacked cover  70  is not restricted by the slide restricting portions  41 . That is, when the first stacked cover  45  is open, a user can release the engagement between the first slide engagement pieces  74  and the first engagement holes  48  by sliding the second stacked cover  70  in the first top cover removal direction, thereby removing the second stacked cover  70  from the first top cover attachment surface  46 . 
         [0069]    Thus, in the multifunction device  1  according to the present embodiment, when the first stacked cover  45  is closed and the sheet transport unit  60  is ready to be used, the second stacked cover  70  cannot be removed from the first top cover attachment surface  46  due to the first protruding pieces  73  and the slide restricting portions  41 . That is, with the multifunction device  1 , the second stacked cover  70  is prevented from being removed when a user unintentionally contacts the second stacked cover  70 . 
         [0070]    In the multifunction device  1  according to the present embodiment, when the first stacked cover  45  is open, the engagement between the first slide engagement pieces  74  and the first engagement holes  48  can be released by sliding the second stacked cover  70  in the first top cover removal direction. That is, with the multifunction device  1 , the second stacked cover  70  can be removed from the first stacked cover  45  by performing simple operations of opening the first stacked cover  45  and sliding the second stacked cover  70  in the first top cover removal direction. 
         [0071]    Next, the structure of the first side-by-side cover  80  according to the present embodiment will be described in detail with reference to the drawings. As illustrated in  FIGS. 1 to 4 , the first side-by-side cover  80 , which is made of a transparent resin, forms the right side of the upper surface of the sheet cover  25 . The first side-by-side cover  80  is removably attached to the second top cover attachment surface  50 . The decorative sheet D having a predetermined pattern can be held between the first side-by-side cover  80  and the second top cover attachment surface  50 . 
         [0072]    Second slide holes (not shown) are formed at two left-hand corners of the second top cover attachment surface  50 . The second slide holes have shapes similar to those of the first slide holes, and second protruding pieces  83  of the first side-by-side cover  80  are inserted into the second slide holes. Second engagement holes (not shown) are formed at two right-hand corners of the second top cover attachment surface  50 . The second engagement holes have shapes similar to those of the first engagement holes  48 . The second engagement holes and second slide engagement pieces  84  of the first side-by-side cover  80  cooperatively serve to removably attach the first side-by-side cover  80  to the second top cover attachment surface  50 . 
         [0073]    As illustrated in  FIG. 9 , the first side-by-side cover  80  includes a flat panel portion  81 , a side panel portion  82 , the second protruding pieces  83 , the second slide engagement pieces  84 , and a lock piece  85 . The flat panel portion  81  has substantially the same shape as the second top cover attachment surface  50 . The decorative sheet D is held by the second protruding pieces  83  and the second slide engagement pieces  84  so as to extend along the flat panel portion  81 . The side panel portion  82  extends in the right downward direction from the right edge of the flat panel portion  81 . 
         [0074]    The second protruding pieces  83  extend downward from the left-hand corners of the flat panel portion  81 , and have shapes substantially the same as the first protruding pieces  73 . When attaching the first side-by-side cover  80 , the second protruding pieces  83  are slid into the second slide holes. 
         [0075]    The second slide engagement pieces  84  are formed at ends of the side panel portion  82  in the front-rear direction and extend leftward from the side panel portion  82  along the flat panel portion  71 . When attaching the first side-by-side cover  80 , the second slide engagement pieces  84  enter the second engagement holes formed in the second top cover attachment surface  50  as the first side-by-side cover  80  slides. Therefore, the first side-by-side cover  80  is removably attached to the second top cover attachment surface  50  using the second slide engagement pieces  84  and the second engagement holes. 
         [0076]    A direction in which the first side-by-side cover  80  is slid when removing the first side-by-side cover  80  (toward the right of the multifunction device  1 ) will be referred to as a second top cover removal direction, and the opposite direction will be referred to as a second top cover attachment direction. 
         [0077]    Each of the second protruding pieces  83  and the second slide engagement pieces  84  has a slit extending along the flat panel portion  81 . When edges of the decorative sheet D are inserted into the slits, the second protruding pieces  83  and the second slide engagement pieces  84  serve to hold the decorative sheet D along the flat panel portion  81  (see  FIGS. 10 and 11 ). Therefore, the pattern of the decorative sheet D can be seen through the first side-by-side cover  80 , which is made of a transparent resin. The decorative sheet D can be replaced with a decorative sheet having a different pattern by removing the first side-by-side cover  80  from the second top cover attachment surface  50 . 
         [0078]    The lock piece  85  protrudes from a surface opposite the second top cover attachment surface  50  in a middle portion of the left edge of the first side-by-side cover  80  in the front-rear direction. The lock piece  85  and a slide restricting member  51 , which is formed on the second top cover attachment surface  50 , cooperatively restrain the first side-by-side cover  80  from being slid in the second top cover removal direction. 
         [0079]    The slide restricting member  51  includes a recessed portion and a lug portion (see  FIGS. 10 and 11 ). The recessed portion is formed in a middle part of the left edge of the second top cover attachment surface  50  and is recessed downward. The lug portion protrudes upward along the right edge of the recess. When the first side-by-side cover  80  is attached the second top cover attachment surface  50 , the slide restricting member  51  is positioned downstream of the lock piece  85  of the first side-by-side cover  80  in the second top cover removal direction. At this time, an end of the slide restricting member  51  (the left end in  FIGS. 10 and 11 ) contacts a side surface on the downstream side of the lock piece  85  in the second top cover removal direction. Therefore, in the multifunction device  1 , the first side-by-side cover  80  cannot be removed from the second top cover attachment surface  50  by simply sliding the first side-by-side cover  80  in the second top cover removal direction, because the sliding amount of the first side-by-side cover  80  is restricted. 
         [0080]    Next, operations of attaching the first side-by-side cover  80  to the second top cover attachment surface  50  and removing the first side-by-side cover  80  from the second top cover attachment surface  50  will be described in detail with reference to the drawings. As illustrated in  FIG. 10 , to remove the first side-by-side cover  80 , it is necessary to separate the lock piece  85  of the first side-by-side cover  80  from the slide restricting member  51  of the second top cover attachment surface  50  and enable the first side-by-side cover  80  to be moved in the second top cover removal direction. Therefore, a user has to lift the left edge of the first side-by-side cover  80  (which is adjacent to the second side-by-side cover  30 ). 
         [0081]    As illustrated in  FIG. 1  and other figures, the second side-by-side cover  30  is disposed adjacent to the left side of the first side-by-side cover  80 . Therefore, when the second side-by-side cover  30  is at the closed position (see  FIGS. 1 and 10 ), a user cannot lift the left edge of the first side-by-side cover  80  from below. That is, when the second side-by-side cover  30  is at the closed position, the lock piece  85  and the slide restraining lug  51  cooperatively restrict in the first side-by-side cover  80  from being moved in the second top cover removal direction (see  FIG. 10 ). Therefore, with the multifunction device  1 , even if a user unintentionally contacts the first side-by-side cover  80 , the first side-by-side cover  80  is prevented from being removed from the second top cover attachment surface  50 . 
         [0082]    As described above, the second side-by-side cover  30  is rotatable around the tray shaft  31 . When the second side-by-side cover  30  is rotated by a predetermined amount to a predetermined position (for example, see  FIGS. 2 and 11 ), the recess  37  is connected to the outside of the sheet cover  25 . That is, when the second side-by-side cover  30  is at the predetermined position, a user can hook his/her finger on the left edge of the lower surface of the first side-by-side cover  80  from the outside of the sheet cover  25  and lift the first side-by-side cover  80 . 
         [0083]    When the left edge of the first side-by-side cover  80  is lifted, the lock piece  85  of the first side-by-side cover  80  is located above the slide restricting member  51  of the second top cover attachment surface  50 . The lock piece  85  is disposed in the middle portion of the left edge of the first side-by-side cover  80 , at which the first side-by-side cover  80  is maximally deflected when the first side-by-side cover  80  is lifted by a user. Therefore, the user can move the lock piece  85  to a position above the slide restricting member  51  without applying a large force. In this state, the slide restricting member  51  is not present on the downstream side of the lock piece  85  in the second top cover removal direction, so that the user can remove the first side-by-side cover  80  from the second top cover attachment surface  50  by sliding the first side-by-side cover  80  in the second top cover removal direction. 
         [0084]    Thus, in the multifunction device  1  according to the present embodiment, the lock piece  85  and the slide restricting member  51  cooperatively serve to restrict the first side-by-side cover  80  from being slid in the second top cover removal direction. Therefore, with the multifunction device  1 , even if a user unintentionally contacts the first side-by-side cover  80 , the first side-by-side cover  80  is prevented from being removed from the second top cover attachment surface  50 . 
         [0085]    In the multifunction device  1  according to the present embodiment, it is necessary to lift the left edge of the first side-by-side cover  80  to enable the first side-by-side cover  80  to be slid in the second top cover removal direction. When the first side-by-side cover  80  is lifted, the first side-by-side cover  80  is allowed to be slid in the second top cover removal direction. Therefore, a user can release the engagement between the second slide engagement pieces  84  and the second engagement holes and remove the first side-by-side cover  80  from the second top cover attachment surface  50  by sliding the first side-by-side cover  80  in the second top cover removal direction. 
         [0086]    To lift the left edge of the first side-by-side cover  80 , it is necessary to apply an upward force to the left edge of the first side-by-side cover  80  from below. Therefore, it is necessary to rotate the second side-by-side cover  30  by a predetermined amount to connect the recess  37 , which is adjacent to the left edge of the first side-by-side cover  80 , to the outside of the sheet cover  25  so that a user can contact the lower surface of the left edge of the lower surface of the first side-by-side cover  80  with his/her finger. That is, with the multifunction device  1 , the user can remove the first side-by-side cover  80  from the second top cover attachment surface  50  by performing simple operations of rotating the second side-by-side cover  30  by a predetermined amount and of lifting the left edge of the first side-by-side cover  80  and sliding the first side-by-side cover  80  in the second top cover removal direction. 
         [0087]    Heretofore, an embodiment of the present invention has been described. However, the present invention is not limited to the embodiment described above, and can be modified within the sprit and scope of the present invention. For example, in the embodiment described above, the multifunction device  1  having the functions of a scanner, a copier, a printer, and a facsimile is used as an example. However, the present invention is not limited thereto. As long as an apparatus has the function of an auto document feeder (ADF), other functions are optional. 
         [0088]    In the embodiment described above, the appearance of the multifunction device  1  is customized by using a transparent resin as the material of the second stacked cover  70  and the first side-by-side cover  80  and thereby making the pattern of the decorative sheet D visible through the second stacked cover  70  and the first side-by-side cover  80 . However, the present invention is not limited thereto. That is, the material of the second stacked cover  70  and the first side-by-side cover  80  need not be a transparent resin, and the second stacked cover  70  and the first side-by-side cover  80  may have patterns thereon. 
         [0089]    In the embodiment described above, the multifunction device  1  has an attachment mechanism for the second stacked cover  70  and an attachment mechanism for the first side-by-side cover  80 . However, the multifunction device  1  may have only one of the attachment mechanisms.