Abstract:
A sheet conveying apparatus that conveys a sheet serving as a recording medium and effectively reduces energy consumption includes a movable sheet supporting device configured to support sheets, a sheet size detecting device configured to detect a size of the sheets by detecting a location of the sheet supporting device, a gap detecting device configured to detect a gap between the sheets and the sheet supporting device, and a reporting device configured to notify an operator of a gap detected by the gap detecting device.

Description:
PRIORITY STATEMENT 
       [0001]    The present patent application claims priority under 35 U.S.C. §119 from Japanese Patent Application No. 2006-219378, filed in the Japan Patent Office on Aug. 11, 2006, the content and disclosure of which are hereby incorporated by reference herein in their entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present disclosure generally relates to a sheet conveying apparatus and an image forming apparatus using the same, for example, printers, facsimiles, copiers, and multifunctional machines including functions of printer, facsimile, and copier. 
         [0004]    2. Discussion of the Related Art 
         [0005]    A conventional image forming apparatus may include an image bearer, an image fixing device, a transfer-sheet storage device, a transfer-sheet size detecting device, a conveyance device, a transfer-sheet detecting device, a timing device, an operational device, and a control device. The control device uses a first threshold and a second threshold smaller than the first threshold for every transfer-sheet size. The first threshold is used for detecting a sheet jam on the transfer-sheet conveyance path. 
         [0006]    When the transfer-sheet conveyance time of a sheet, which is determined by the transfer-sheet detecting device and the timing device, is longer than the first threshold, a sheet jam is diagnosed and the image forming operation is stopped immediately. When the transfer-sheet conveyance time is shorter than the first threshold but not shorter than the second threshold and this situation is detected two consecutive times or more, the transfer-sheet size is considered irregular. In this case, conveyance of the following transfer sheet is prohibited, and an image forming operation is stopped after forming an image on the already fed transfer-sheet and discharging the sheet from the image forming apparatus. When the transfer-sheet conveyance time is shorter than the first threshold but not shorter than the second threshold and this situation is not detected consecutively, an image forming operation is allowed to continue. 
         [0007]    In the image forming apparatus, the sheet length is measured using a sheet sensor disposed along the sheet conveyance path. The sheet length is compared with two or more thresholds, the number of which is determined based on the sheet size preset in the image forming apparatus, to detect a sheet jam and a sheet of irregular size. When the sheet length is different from the preset sheet size, the sheet is ejected without stopping the conveyance (i.e., without regarding the situation as a sheet jam). Therefore, at least one sheet must be conveyed to diagnose a sheet jam. When the sheet size is erroneously preset, one sheet and ejecting energy are consumed in vain. 
       SUMMARY OF THE INVENTION 
       [0008]    An embodiment of the present invention is directed to a sheet conveying apparatus and an image forming apparatus using the same, which convey a sheet serving as a recording medium and effectively reduce energy consumption. In the embodiment, a sheet conveying apparatus includes a movable sheet supporting device configured to support sheets, a sheet size detecting device configured to detect a size of the sheets by detecting a location of the sheet supporting device, a gap detecting device configured to detect a gap between the sheets and the sheet supporting device, and a reporting device configured to notify an operator of the existence of the gap detected by the gap detecting device. 
         [0009]    Additional features and advantages of the present invention will be more fully apparent from the following detailed description of embodiments, the accompanying drawings and the appended claims. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
           [0011]      FIG. 1  is a perspective diagram showing a state in which a sheet feed tray is pulled out from an image forming apparatus according to an embodiment of the present invention; 
           [0012]      FIG. 2  is an exploded perspective view of a size detection board which constitutes a size detection device in the image forming apparatus of  FIG. 1 ; 
           [0013]      FIG. 3  is a perspective diagram showing a disposition of the size detection board in the image forming apparatus of  FIG. 1 ; 
           [0014]      FIG. 4  is a plan view of a sheet feed tray in the image forming apparatus of  FIG. 1 ; 
           [0015]      FIG. 5  is a cross-sectional view of the sheet feed tray of  FIG. 4 ; 
           [0016]      FIG. 6  is an expanded sectional view along a line X-X of  FIG. 4 ; 
           [0017]      FIG. 7  is a plan view of an example of a sheet feed tray in the image forming apparatus of  FIG. 1 ; 
           [0018]      FIG. 8  is a plan view of an example of a sheet feed tray in the image forming apparatus of  FIG. 1 ; 
           [0019]      FIG. 9  is an expanded sectional view along a line Y-Y of  FIG. 8 ; 
           [0020]      FIG. 10  is a plan view of another example of a sheet feed tray in the image forming apparatus of  FIG. 1 ; and 
           [0021]      FIG. 11  is an expanded sectional view along a line Z-Z of  FIG. 10 . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0022]    Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, embodiments of the present disclosure, which are applied to a tandem-type color image forming apparatus, are explained below. 
         [0023]    I the following description, it is to be understood that if an element or layer is referred to as being “on,” “against,” “connected to” or “coupled to” another element or layer, then it may be either directly on, against, connected or coupled to that other element or layer or intervening elements or layers may be present. By contrast, if an element is referred to as being “directly on”, “directly connected to” or “directly coupled to” another element or layer, then there are no intervening elements or layers present. Like numbers refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0024]    Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, a term such as “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
         [0025]    Although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers and/or sections, it should be understood that these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention. 
         [0026]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “includes” and/or “including”, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
         [0027]    In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner. 
         [0028]    Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, particularly to  FIG. 9 , an example of a feeding tray of an image forming apparatus according to embodiments is described. 
         [0029]      FIGS. 1 through 3  illustrate an example of an image forming apparatus including an automatic size detection sheet feed tray, according to one embodiment of the present disclosure.  FIG. 1  is a perspective diagram in the status that one of the sheet feed trays is pulled out from an image forming apparatus according to an embodiment of the present invention.  FIG. 2  is an exploded perspective view of a size detection board which constitutes a size detection device in the image forming apparatus of  FIG. 1 .  FIG. 3  is a perspective diagram showing the disposition of the size detection board in the image forming apparatus of  FIG. 1 . 
         [0030]    In a sheet feeding unit  1  of the image forming apparatus, a sheet feed tray  10  is attached. Side fences  11  and  12 , and an end fence  13  are attached to the sheet feed tray  10 . A user pulls out the sheet feed tray  10  which stores recording sheets P in a direction A in  FIG. 1 . The side fences  11  and  12 , and the end fence  13 , are movable so as to hold the sheets P in various sizes in directions C and D in  FIG. 3 . When the positions of the side fences  11 ,  12  and the end fence  13  are fixed due to the size of the sheet P, the positions of size detection boards  2 ,  3  arranged on the back side of the sheet feed tray  10 , which are rotated by a link mechanism, not shown, are fixed. Further, the combination of concavo-convex portions  2   a  and  3   a  of the size detection boards  2 ,  3 , which varies depending on sheet size, is fixed. A push switch  20  detects the concavo-convex portions  2   a  and  3   a . Therefore, the size of the sheets P in the sheet feed tray  10  is detected. That is, the size detection boards  2 ,  3  and the push switch  20  constitute a sheet size detection device. The side fences  11  and  12  are constituted so that they may move symmetrically to a centerline of the sheet P via a rack-and-pinion mechanism  4 . The side fences  11  and  12  are movable parallel to the direction A in  FIG. 1 . The side fences  11  and  12  are movable perpendicular to the direction A in  FIG. 1 . 
         [0031]      FIGS. 4 through 11  illustrate examples of a sheet feed tray according to embodiments of the present disclosure.  FIG. 4  is a plan view of a sheet feed tray in the image forming apparatus of  FIG. 1 .  FIG. 5  is a cross-sectional diagram of the sheet feed tray of  FIG. 4 .  FIG. 6  is an expanded sectional view along a line X-X of  FIG. 4 .  FIG. 7  is a plan view of an example of a sheet feed tray in the image forming apparatus of  FIG. 1 .  FIG. 8  is a plan view of an example of a sheet feed tray in the image forming apparatus of  FIG. 1 .  FIG. 9  is an expanded sectional view along a line Y-Y of  FIG. 8 .  FIG. 10  is a plan view of another example of a sheet feed tray in the image forming apparatus of  FIG. 1 .  FIG. 11  is an expanded sectional view along a line Z-Z of  FIG. 10 . In  FIGS. 4 and 5 , the above-mentioned sheet size detection device is provided on the sheet feed tray  10 . The size detection boards  2 ,  3  and the push switch  20  are not illustrated in  FIGS. 4 and 5 . A sole plate  5  is provided in the sheet feed tray  10 . The side fences  11  and  12  and the end fence  13  position the sheets P on the sole plate  5 . When the sheet feed tray  10  is pushed into the sheet feeding unit  1  in a direction B in  FIG. 7 , the sole plate is elevated with an elevating mechanism, not shown, in which a supporting point  6  is used for elevating. Therefore, the sheets P are elevated up to a given position, and fed one by one with a separating mechanism, not shown. The sheet feed tray  10  can be pushed into the sheet feeding unit  1 , and can be pulled out from the sheet feeding unit  1 . When the sheet feed tray  10  is pulled out from the sheet feeding unit  1 , the sheets P can be supplied, and the side fences  11  and  12  and the end fence  13  can be moved to attach to and detach from the end of the sheets P. 
         [0032]    The side fences  11  and  12  are box-type hollow objects. The side fence  11  has a side surface  11   a  which contacts an end of the sheets P. The side fence  12  has a side surface  12   a  which contacts an end of the sheets P. Therefore, the side fences  11  and  12  support the sheets P. In  FIG. 4 , a right end of the side fence  11  has a width W which is wider than a left end of the side fence  11 . In  FIG. 6 , a gap detection sensor  111  and a gap detection filler  110  as a gap detection device are arranged in the hollow of the side fence  11 . In  FIG. 9 , the gap detection filler  110  protrudes to the end of the sheets P through an opening  113  in the side fence  11  when there is a gap between the side surface  11   a  and the end of the sheets P. The gap between the side surface  11   a  and the end of the sheets P tends to arise because the sheets P tend to move toward the rear side by inertia when the sheet feed tray  10  is pushed into the sheet feeding unit  1 . Therefore, the gap detection sensor  111  and the gap detection filler  110  are provided in the hollow of the side fence  11 . 
         [0033]    The end fence  13  is a box-type hollow object. The end fence  13  has a side surface  13   a  which contacts an end of the sheets P. It should be noted that the end fence  13  and the side fence  12  are not necessarily hollow objects. 
         [0034]    When there is little gap between the end of the sheets P and the side surface of the side fences  11  and  12  as shown in  FIG. 4 , the gap detection filler  110  is in the hollow of the side fence  11  as shown in  FIG. 6 . Therefore, a lower part of the gap detection filler  110  blocks light in the gap detection sensor  111 , and the gap detection sensor  111  can judge the gap. Further, a sheet size may be detected by the size detection boards  2 ,  3  and the push switch  20  without error. 
         [0035]    When a user sets the side fences  11  and  12  having gaps G 1  and G 2  as shown in  FIG. 7 , or when the side fences  11  and  12  are moved to have the gaps due to a fault of a stopper, not shown, the size detection boards  2 ,  3  rotate to irregular positions. Therefore, a detecting result of a sheet size by the push switch  20  which detects the concavo-convex portions  2   a  and  3   a  is different from the sheet size of the sheets P. When the sheets P are fed without noticing the difference, a sheet jam, a skew, or a fault of image positioning may occur. 
         [0036]    When there are gaps G 1  and G 2  as shown in  FIG. 7 , or a gap G 3  between the side surface  11   a  and the end of the sheets P as shown in  FIG. 8 , the gap detection filler  110  protrudes to the end of the sheets P through the opening  113  in the side fence  11  as shown in  FIG. 9 . Therefore, the gap detection sensor  111  may not detect the gap correctly, and the sheet size may not be detected correctly by the size detection boards  2 ,  3  and the push switch  20 . 
         [0037]    When the detection sensor  111  cannot detect the gap correctly, it is assumed that there is the gap G 3  between the side surface  11   a  and the end of the sheets P as shown in  FIG. 8 , and this information is sent to a controller, not shown, of a main body of the image forming apparatus. Further, the controller sends a message to a user using a display, not shown, and the existence of the gap G 3  is reported to a user. The user resets the sheets P so as not to have the gap G 3 . A warning on the display and/or an audio warning may be used to inform the user. 
         [0038]    The user who receives notification of the existence of the gap G 3  adjusts the position of the side fence  11  (and by necessity the side fence  12 ), thus reducing the gap G 3 . Thereby, as mentioned above, the sheet size may be detected correctly by the size detection boards  2 ,  3  and the push switch  20 . 
         [0039]    As mentioned above, the gap detection information shows whether the disposition of the sheet P within the sheet feed tray  10  is correct. Therefore, energy cost is reduced because it is not necessary to convey at least one sheet in vain to detect an error of the sheet size. Further, the gap detection filler  110  constantly contacts the end of the sheet P and the gap is securely detected irrespective of the number of the sheets P. 
         [0040]    Another example is explained with reference to  FIG. 10  and  FIG. 11 . The composition of this example is almost the same as that of the above-mentioned example, and the same reference numerals are given to identical parts and a description thereof is omitted. A different composition is explained below. In  FIG. 10  and  FIG. 11 , the gap detection sensor  111  electrically connects to an electric conduction rail  15  provided in the sheet feed tray  10  through a sliding member  16  provided in the side fence  11 . When the sheet feed tray  10  is set in the sheet feeding unit  1 , the electric conduction rail  15  is electrically connected through a connector  17 . That is, when the side fence  11  is moved, the sliding member  16  slides along the electric conduction rail  15 . Therefore, the electric connection is maintained irrespective of the location of the side fence  11 . The electric conduction rail  15  is provided under the sole plate  5  and parallel to a direction B in  FIG. 10 . One end of the electric conduction rail  15  connects the connector  17  on the outside surface of the sheet feed tray  10 . The other end of the electric conduction rail  15  contacts the lower part of the sliding member  16 . 
         [0041]    The gap detection filler  110  has a curved surface or a beveling form surface which faces the sheets. As shown in  FIG. 9  and  FIG. 11 , a protruding portion of the gap detection filler  110  from the side fence  11  is curved. Therefore, the sheets are not caught by the gap detection filler  110  when the sheet feed tray  10  is supplied with the sheets from various directions (e.g. up, side, slant), and the gap detection filler  110  smoothly moves into the side fence  11 . 
         [0042]    When there is little gap between the end of the sheets P and the side surface of the side fences  11  and  12  as shown in  FIG. 10 , the gap detection filler  110  is in the hollow of the side fence  11  as shown in  FIG. 11 . Therefore, a lower part of the gap detection filler  110  blocks light in the gap detection sensor  111  and the gap detection sensor  111  can judge the gap. Further, a sheet size may be detected by the size detection boards  2 ,  3  and the push switch  20  without error. In this example, when there are gaps G 1  and G 2  as shown in  FIG. 7 , or a gap G 3  between the side surface  11   a  and the end of the sheets P as shown in  FIG. 8 , the gap detection filler  110  protrudes to the end of the sheets P through the opening  113  of the side fence  11  as shown in  FIG. 9 . Therefore, the gap detection sensor  111  may not detect the gap correctly, and the sheet size may not be detected correctly by the size detection boards  2 ,  3  and the push switch  20 . Further, a controller sends a message to a user using a display, not shown, and the existence of the gap is reported to the user. The user may then reset the sheets P so as not to have the gap. 
         [0043]    Since the gap detection filler  110  hangs down by the self-weight, it can evacuate in the side fence  11  with the small load intensity by the sheets. However, the gap detection filler  110  can easily swing at the opening and closing of the sheet feed tray  10 . Therefore, the gap detection sensor  111  can make an error. For this problem, the gap detection sensor  111  is controlled so as not to detect during a given period after turning on electricity. This may reduce the detecting error. The given time may be about from 1 to 2 seconds. The side of the gap detection sensor  111 , which faces the sheets, may be constituted with heavy materials so as to reduce the easiness of the swing. 
         [0044]    This example has the gap detection sensor  111 , the electric conduction rail  15 , the sliding member  16 , and the connector  17  in the sheet feed tray  10 . Therefore, a location of the gap detection filler  110  may be detected irrespective of the sheet size in the sheet feed tray  10 . 
         [0045]    Although desirable examples of the gap detection sensor  111  and the gap detection filler  110  are shown, as long as the same effect can be expected other members, such as photosensors or microswitches, may be used. In addition, the gap detection device is provided in the side fence  11 . However, alternatively, it may be provide in the side fence  12 . Moreover, the sheet feeding unit is provided in the image forming apparatus. However, alternatively, it may be provide in a scanner apparatus. Finally, a film type sheet may be used as the sheet P. It should be noted that design details may be changed and corrected arbitrarily in the implementation of the present invention in its several embodiments. 
         [0046]    Furthermore, in the above-described embodiments, descriptions are provided using examples in which the subject matter of the present disclosure is applied to the tandem-type color image forming apparatus. However, it is to be understood that the subject matter of the present disclosure may be applied to other image forming apparatuses such as printers, facsimiles and so forth, and also to a multi-functional image forming apparatus. 
         [0047]    The embodiments being thus described, it should be apparent to one skilled in the art after reading this patent specification that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present disclosure, and all such modifications as would be apparent to one skilled in the art are intended to be included within the scope of the following claims.