Abstract:
Sheet feeding device including: a tray unit having a feeding tray for supporting a loaded-on document&#39;s trailing end, and a tilting tray for supporting its leading end; a feeding unit that feeds loaded-on documents from off the feeding and tilting trays; and an elevating mechanism that raises/lowers the tilting tray between the positions where documents are set onto and fed from it. The tilting tray is elevated by a lever that comes out of an opening in a feeding-unit cover, in which state the tray unit, which is pivotable with respect to the sheet feeding unit, is kept from pivoting. Otherwise, when the tray unit is pivoted upward from or returned to the load-on document position, tilting-tray movement, in conjunction with the pivoting action, with respect to the feeding tray is restrained, preventing negative impact on the tilting tray, and thus improving device manageability.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present invention involves sheet-feeding devices that deliver sheets stacked on a sheet feeding tray to a predetermined position, and in particular relates to sheet feeding devices furnished with a tilting tray free to rise/lower in order to bring sheets into pressure-contact with delivery means. 
         [0003]    2. Description of the Related Art 
         [0004]    In sheet feeding devices provided in image-capturing apparatuses, copiers, or the like, to convey sheets to a predetermined image-capturing position, it is known to dispose the sheet discharging tray below the sheet feeding tray, and to form in the shape of a U the conveying path along which sheets on the sheet feeding tray are conveyed to the sheet discharging tray via the image-capturing position. In this type of sheet feeding device, the sheet feeding tray is pivotable upward so as to take a sheet out from the sheet feeding tray or to remove a sheet jammed in a sheet discharging section. 
         [0005]    Meanwhile, a sheet feeding device capable of handling a large number of sheets at a time has been desired. A known feeding device of this type adopts a sheet feeding tray unit composed of a sheet feeding tray that supports the trailing end of a sheet, and a tilting tray free to rise/lower to support a leading end of the sheet (for example, Japanese Unexamined Pat. App. Pub. No. 2003-118851). 
         [0006]    The sheet feeding tray unit, composed of the sheet feeding tray and the tilting tray, uses an elevating mechanism including an elevating lever and a driving motor for the elevating lever in order to raise and lower the tilting tray. The elevating mechanism is provided behind the tilting tray. The tilting tray is pivotably supported by the sheet feeding tray at one end and is free at the other end. The elevating lever pushes up the rear side of the tilting tray to raise the tilting tray. The driving motor is reversely rotated to allow the elevating lever to pivot away from the rear surface of the tilting tray, whereby the tilting tray lowers under its own weight. 
         [0007]    The system just described controls the tilting tray by receiving a sheet-feeding-command signal from the image-capturing apparatus and actuating the elevating lever to raise the tilting tray from a setting position where sheets are set into place on the tilting tray, to a delivery position where the uppermost one of the sheets abuts against a delivery roller. 
         [0008]    However, in the conventional sheet feeding device, the elevating mechanism is fitted integrally to the sheet feeding tray unit. Thus, when the sheet feeding tray unit is to be pivoted, the weight of the elevating mechanism acting on the sheet feeding unit may distort the tray, the pivoting operation might not be able to take place smoothly, or shock on the sheet feeding tray unit when pivoting may occur. The adverse influence of the elevating mechanism&#39;s weight has made handling the tray unit challenging. 
         [0009]    A sheet feeding device that has been proposed to address this problem has an elevating mechanism made up pf an elevating lever, a driving motor, and associated components, and provided in the main body of the device, the elevating lever having a leading end extending to below the tilting tray (for example, Japanese Unexamined Pat. App. Pub. No. 2001-139162). This configuration resolves the above-described problem because the sheet feeding tray unit is separate from the elevating mechanism. 
         [0010]    However, when the sheet feeding tray is swung upward while the tilting tray is rising by being pushed up along the rear surface of the elevating lever, the tilting tray is supported on the sheet feeding tray only at one end and is free at the other end. Furthermore, the elevating lever is exposed from a device cover. Consequently, when the sheet feeding unit is returned to the sheet setting position, there is a chance that the tilting tray may go in underneath the elevating lever. A further danger is that the leading end of the tilting tray may knock against the elevating lever. 
         [0011]    Moreover, when the sheet feeding unit is swung, the other, free end of the tilting tray pivots freely, colliding against the sheet feeding tray or other components and making noise. A further problem therein is that the components may be damaged. 
       BRIEF SUMMARY OF THE INVENTION 
       [0012]    The present invention has been made in view of the above-described problems. An object of the present invention is to provide a sheet feeding device having a sheet feeding tray unit including a tilting tray supported by a sheet feeding tray at one end, the device preventing the tilting tray from being affected when the sheet feeding tray unit is caused to pivot upward from the sheet set position or returned to the set position. 
         [0013]    The present invention provides a sheet feeding device including a sheet feeding tray unit having a sheet feeding tray on which a sheet-feeding-direction trailing end of a set sheet is supported and a tilting tray which is able to rise and lower freely and which supports a sheet-feeding-direction leading end of the set sheet, a sheet feeding unit having sheet feeding means for feeding the set sheet on the sheet feeding tray and the set sheet on the tilting tray, and elevating means for elevating the tilting tray between a set position where the sheet is set on the tilting tray and a sheet feeding position where the sheet is fed from the tilting tray, the sheet feeding unit being configured to be able to turn freely with respect to the sheet feeding unit. 
         [0014]    According to a first aspect of the present invention, the sheet feeding device has means for governing turning of sheet feeding tray unit while the elevating lever elevating the tilting tray is in a raised position. 
         [0015]    According to a second aspect of the present invention, the elevating lever is provided in an opening formed in a cover member of the sheet feeding unit. To raise or lower the tilting tray, the elevating lever projects out of the opening to push up and raise the tilting tray. 
         [0016]    According to a third aspect of the present invention, the sheet feeding device includes restraining means for restraining movement of the tilting tray with respect to the sheet feeding tray in conjunction with a pivoting action of turning the sheet feeding tray unit with respect to the sheet feeding unit. 
         [0017]    This configuration can prevent noise or damage to components which may occur when the sheet feeding tray unit is caused to pivot upward from a sheet set position or returned to the set position, and other possible problems such as movement of the tilting tray to below the elevating lever. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0018]      FIG. 1  is a sectional view showing a general configuration of a sheet feeding device according to the present invention; 
           [0019]      FIG. 2  is a perspective view of a sheet feeding tray unit of the document feeding device according to the present invention; 
           [0020]      FIG. 3  is a sectional view taken along line III-III in  FIG. 2 ; 
           [0021]      FIG. 4  is a sectional view showing that a sheet feeding tray has been caused to pivot upward; 
           [0022]      FIG. 5  is a sectional view showing that governing means prevents the sheet feeding unit from pivoting upward; 
           [0023]      FIG. 6  is a sectional view showing that the governing means is released to allow the sheet feeding tray unit to pivot upward; 
           [0024]      FIG. 7  is a sectional view showing the engagement relationship between an engaging projection and a restraining member; 
           [0025]      FIG. 8  is a perspective view showing the configuration of the governing member; and 
           [0026]      FIG. 9  is a sectional view showing that the sheet feeding tray unit has been caused to pivot upward. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    Embodiments of a sheet feeding device according to the present invention will be described below in detail with reference to the attached drawings.  FIG. 1  is a sectional view showing a sheet feeding device according to the present invention mounted in an image-capturing apparatus. In  FIG. 1 , reference character A denotes a document feeding device as a sheet feeding device mounted at the top of an image-capturing apparatus H. The document feeding device A conveys a document so that the document passes over first contact glass  1  provided on a top surface of the image-capturing apparatus H. 
         [0028]    The image-capturing apparatus H comprises a first image-data capturing unit  3  that captures document image data (“image data” herein broadly meant to include text as well as pictographic data) by irradiating a document with light emitted by a light source such as a lamp via the first contact glass  1  so that reflected light from the document is further reflected by a plurality of mirrors, and photoelectrically converting the light by a photoelectric converting means such as a CCD via a lens. A first data-capturing section  5  of the image-capturing apparatus H is thus constructed on a top surface of the contact glass  1 . The image-capturing apparatus H comprises second contact glass  2  behind the first contact glass  1 . The second contact glass  2  has an area sufficient to place a document thereon. The document image data can be captured by opening the document feeding device A upward, placing a thick document such as a book or a magazine on the second contact glass  2 , and moving the first image-data capturing unit  3  in a sub-scanning direction. 
         [0029]    The document feeding device A comprises a sheet feeding tray unit Ton which a large number of documents can be placed at a time, a sheet discharging tray  11  in which documents from which document image data has been captured by the image-capturing apparatus H are housed, a pressing cover  12  that presses the second contact glass  2 , and a U-shaped conveying path  13  along which each of the documents is conveyed from the sheet feeding tray unit T to the sheet discharging tray  11 . The pressing cover  12  is composed of, for example, a porous member such as sponge and a film member such as a white Mylar™ resin. 
         [0030]    The document feeding device A according to the present embodiment has a second image-data capturing unit  4  installed at a bent portion of the U-shaped conveying path  13  to capture an image data from a back surface of a document. Like the first image-data capturing unit  3 , the second image-data capturing unit  4  captures document image data by irradiating a document with light emitted by a light source such as a lamp via contact glass  7 , forming a part of the conveying path  13 , so that reflected light from the document is further reflected by a plurality of mirrors, and photoelectrically converting the light by a photoelectric converting means such as a CCD via a lens. A top surface of the contact glass  7  is configured as a second data capturing section  6  of the image-capturing apparatus H. Thus, in the document feeding device A, the second image-data capturing unit  4  captures document image data from one surface of the document passing through the second data capturing section  6 , located in the middle of the conveying path  13 . The first image-data capturing unit  3  captures document image data from the other surface of the document passing through the first data capturing section  5 . This enables a sharp reduction in the time required to capture image data from double-side documents. 
         [0031]    The U-shaped conveying path  13  comprises a delivery roller  21  that delivers a document from the sheet feeding tray unit T, separating means made up of a sheet feeding roller  22  and a separating pad  23  to separately feed each of the documents delivered from the delivery roller  21 , and a registration roller pair  24  having a nip point against which the leading end of the document fed from the sheet feeding roller  22  abuts and is aligned for de-skewing, the registration roller pair  24  being subsequently driven to feed the document downstream. The conveying path  13  comprises a feeding roller pair  25  that feeds the document from the registration roller pair  24  out to the second data capturing section  6  and the first data capturing section  5 , a first data-capturing roller pair  26  that feeds the document from the feeding roller pair  25  to the second data capturing section  6 , and a second data-capturing roller pair  27  that feeds the document from one surface of which image data has been captured, to the first data capturing section  5 . The conveying path  13  further comprises a third data-capturing roller pair  28  that carries out the document having passed through the second data capturing section  6  and the first data capturing section  5 , a first sheet discharging roller  29  which receives the document from both surfaces of which image data has been captured, from the third data-capturing roller pair  28  and which conveys the document toward the sheet discharging tray  11 , and a second sheet discharging roller pair  30  that discharges the document to the sheet discharging tray  11 . In the present embodiment, the conveying path  13  is configured as a sheet feeding unit F incorporating a plurality of components. 
         [0032]    Now, description will be given of a document conveying operation of the document feeding device A configured as described above. First, an empty sensor S 1  senses that a document has been placed on the sheet feeding tray unit T In response to a sheet feeding command signal from the image-capturing apparatus H, the delivery roller  21  and the sheet feeding roller  22  are driven. In this way, a plurality of documents having been placed on the sheet feeding tray unit T are sequentially delivered, and each of the documents is separated from the others by the separating pad  23  and fed. The registration sensor S 2  senses the leading end of the fed document, which is conveyed a predetermined distance from the point corresponding to the sensing. The leading end of the document abuts against the nip portion of the registration roller pair  24  for alignment and de-skewing. Subsequently, the registration roller pair  24 , the feeding roller pair  25 , and the data-capturing roller pairs  26 ,  27 , and  28  are driven. Thus, the document is conveyed along the U-shaped conveying path  13  so as to be turned upside down. The document passes through the second data capturing section  6  and the first data capturing section  5  in this order. When the document passes through the second data capturing section  6 , image data is captured from one surface of the document. When the document passes through the first data capturing section  5 , image data is captured from the other surface of the document. 
         [0033]    Before the leading end of the document reaches the first sheet discharging roller pair  29 , the first sheet discharging roller pair  29  and the second sheet discharging roller pair  30  have been driven to discharge, onto the sheet discharging tray  11 , the document from the opposite surfaces of which image data has been captured by the second data capturing section  6  and the first data capturing section  5 . 
         [0034]    It should be noted that in the above-described document feeding device A, a shingle-feed detecting sensor GS is provided in the course of the conveying path  13  between the registration roller pair  24  and the feeding roller pair  25 . The shingle-feed detecting sensor GS, having an oscillating unit for emitting ultrasonic waves and a receiving unit for receiving the ultrasonic waves, arranged opposing each other across the path, detects that “shingle-feeding” of documents on the basis of the vibration level of the received ultrasonic waves. Furthermore, an imprinter  8  is provided in a sheet discharging section on a sheet discharging tray  11  side of the conveying path  13 . The imprinter  8  can print about five letters on the surface of the document discharged by the first sheet discharging roller  29  and the second sheet discharging roller  30 . The imprinter prints letters indicating that a document conveying error or a data-capturing error in the first or second image-data capturing unit  3  or  4  has occurred, on the document on which the error has occurred. 
         [0035]    Now, description will be given of the configuration and effects of the sheet feeding tray unit T according to the present invention.  FIG. 2  is a perspective view illustrating the configuration of the sheet feeding tray unit T.  FIG. 3  is a sectional view of the sheet feeding tray unit T. 
         [0036]    As shown in  FIGS. 2 and 3 , the sheet feeding tray unit T according to the present invention is made up of a sheet feeding tray  41  that supports the trailing end of the document, a tilting tray  42  that supports the leading end of the document. The sheet feeding tray  41  has a planar document loading section  41   a , a cover section  41   a  that covers a bottom surface of the tilting tray  42 , and an arm section  41   c  that causes the sheet feeding tray unit T to pivot upward; the cover section  41   b  and the arm section  41   c  are formed integrally with the document loading section  41   a . The tilting tray  42  is made up of a planar member located above the cover section  41   b  of the sheet feeding tray  41 . The tilting tray  42  is continuous with the document loading section  41   a  of the sheet feeding tray  41  to form a loading surface for the leading end of the document. Furthermore, support pins  42   a  provided at respective ends of a trailing end of the tilting tray  42  are rotatably attached to the sheet feeding tray  41 . Thus, the tilting tray  42  rises and lowers between a loading position where the tilting tray  42  cooperates with the document loading section  41   a  of the sheet feeding tray  41  in forming a continuous flat surface on which the document is loaded as shown in  FIG. 3 , and a delivery position where a front side of the tilting tray is raised using the support pins  42   a  as support points so as to contact the top surface of the document with a peripheral surface of the delivery roller  21 . 
         [0037]    The cover section  41   b  of the sheet feeding tray  41  covers the bottom surface of the tilting tray  42  to prevent the possible exposure of an interlocking mechanism of a pair of side governing members  43  described below and an elevating lever  44  that raises the tilting tray  42 . Furthermore, as shown in  FIG. 2 , the arm section  41   c  has a pivoting pin  41   d  at a leading end thereof and pivotably attached to a side wall  50  of the sheet feeding unit F constituting the U-shaped conveying path  13 . Thus, in the sheet feeding tray unit T, the sheet feeding tray  41  and the tilting tray  42  can pivot together around the pivoting pin  41   d , serving as a support point, in a vertical direction with respect to the sheet feeding unit F. The sheet feeding tray unit T is caused to pivot upward, for example, when documents discharged onto the sheet discharging tray  11  are taken out or when a jammed document is removed. 
         [0038]    The tilting tray  42  has the pair of side governing members  43  that govern side ends of the document in a width direction. The side governing members  43  are slidable in the width direction of the document so as to govern the opposite width-wise side ends of the document. The side governing members  43  have the interlocking mechanism that allows one of the side governing members to move slidably in conjunction with the other side governing member. Although not shown, the interlocking mechanism is common and has a rack and a pinion. 
         [0039]    The tilting tray  42  is drivingly raised and lowered by elevating means provided in the sheet feeding unit F. In the present embodiment, the elevating means is composed of: an elevating lever  44  that abuts against a rear surface of the leading end of the tilting tray  42 ; a driving shaft  45  that swings the elevating lever  44  up and down; a plurality of gears (not shown) as transmission means which are coupled to the driving shaft  45 ; and an elevating motor (not shown) that rotates the driving shaft  45  via the plurality of gears. As shown in  FIG. 2 , the elevating lever  44  is a plate member having an engagement hole  44   a  formed in a central portion thereof, and a leading end of the elevating lever  44  extends to immediately below the leading end of the tilting tray  42  and abuts against a rear surface  42   b  (cf.  FIGS. 5A and 5B ) of the tilting tray  42 ; the engagement hole  44   a  will be described below. 
         [0040]    The elevating operation of the tilting tray  42  will be described below. The empty sensor S 1  detects a document loaded on the sheet feeding tray unit T. In response to a sheet feeding command signal from the image-capturing apparatus H, the elevating motor starts forward rotational driving. The forward rotational driving by the motor rotates the driving shaft  45  to cause the elevating lever  44  located at a lower limit position to pivot upward. The pivoting operation causes the leading end of the elevating lever  44  to abut against the rear surface  42   b  of the tilting tray  42  to push up the tilting tray  42 . On the basis of this operation, the leading end of the tilting tray  42  is raised using the support points  42   a  at the trailing end as pivoting support points. The elevating motor stops the driving when the tilting tray  42  rises up to the delivery position where the uppermost surface of the documents loaded on the tilting tray  42  abuts against the delivery roller  21 . In this condition, the delivery roller  21  is driven to deliver the document. 
         [0041]    Following that, on each occasion documents have been delivered a predetermined number times, the elevating motor runs, whereby the elevating lever  44  raises the tilting tray  42 , which is controlled so that the uppermost surface of the documents is always set at the appropriate delivery position. When the empty sensor S 1  detects that no document is present on the sheet feeding tray unit T, the elevating motor starts backward rotational driving. The elevating lever  44  thus pivots downward via the driving shaft  45  to move to the lower limit position. Following on the downward pivoting of the elevating lever  44 , the tilting tray  42  under its own weight lowers to the lower loading position. Now, reference numeral S 4  denotes a delivery-position detecting sensor that detects that the uppermost surface of the documents has reached the delivery position, while reference numeral S 5  denotes a lower-limit position sensor that detects that the elevating lever  44  has moved to the lower limit position. Herein, engaging a projection (not shown) provided on the rear surface of the tilting tray  42  with the engagement hole  44   a , which is provided in the elevating lever  44 , makes it possible to restrain the sheet feeding tray unit T from pivoting upward when elevating lever  44  is rising. 
         [0042]    The document feeding device A has governing means for governing the upward pivoting of the sheet feeding tray unit T while the tilting tray  42  lies above the document-loading position. As shown in  FIG. 5 , the governing means includes an engaging piece  42   c  formed on the rear surface  42   b  of the leading end of the tilting tray  42  so as to project downward, and the engagement hole  44   a , which is rectangular, formed in the central portion of the elevating lever  44 . When the sheet feeding tray unit T is caused to pivot, the engaging piece  42   c  engages the engagement hole  44   a  to restrain the upward pivoting of the sheet feeding tray unit T. The leading end of the engaging piece  42   c  is bent like a key so as to easily engage an end of the engagement hole  44   a . It is important that the engaging piece  42   c  and the engagement hole  44   a  be in a positional relationship such that while the tilting tray  42  lies above the loading position, the engaging piece  42   c  and the engagement hole  44   a  are engaged with each other by causing the sheet feeding tray unit T to pivot. For example, the engaging piece  42   c  and the engagement hole  44   a  may be in a positional relationship such that, as shown in  FIG. 5A , when the leading end of the elevating lever  44  abuts against the rear surface  42   b  of the tilting tray  42 , the engaging piece  42   c  enters the engagement hole  44   a  to raise the tilting tray  42 , or such that the engaging piece  42   c  does not enter the engagement hole  44   a  while the tilting tray  42  lies above the loading position but, as shown in  FIG. 5B , engages into the engagement hole  44   a  when the sheet feeding tray unit T is caused to pivot in the direction of an illustrated arrow. As shown in  FIG. 5B , when the sheet feeding tray unit T is caused to pivot, the engaging piece  42   c  projecting from the rear surface  42   b  of the tilting tray  42  engages the end of the engagement hole  44   a  in the elevating lever  44  in the pivoting direction to inhibit the sheet feeding tray unit T from pivoting further. 
         [0043]    On the other hand, as shown in  FIG. 6 , when the elevating lever  44  moves to the lower limit position, the tilting tray  42  is set in the loading position where the tray  42  cooperates with the document loading section  41   a  of the sheet feeding tray  41  in forming a flat surface. Then, even when the sheet feeding tray unit T is caused to pivot in the direction of the arrow, the sheet feeding tray unit T pivots to an almost vertical position without being inhibited from pivoting because the engagement hole  44   a  in the elevating lever  44  lies off the pivoting trajectory t of the engaging piece  42   c , projecting from the rear surface  42   b  of the tilting tray  42 . Even when the leading end of the elevating lever  44  abuts against the rear surface  42   b  of the tilting tray  42 , the pivoting of the sheet feeding tray unit T is not inhibited provided that the engagement hole  44   a  lies off the pivoting trajectory t of the engaging piece  42   c.    
         [0044]    The governing means has a simple configuration but exerts the following effect. The governing means reliably inhibits the pivoting of the sheet feeding tray unit T while the tilting tray  42  is in the predetermined delivery position. On the other hand, the governing means allows the sheet feeding tray unit T to pivot only when the tilting tray  42  is in the loading position. This prevents the tilting tray from slipping under the elevating lever or colliding against the elevating lever when the tilting tray having pivoted upward is returned to the initial position. 
         [0045]    The document feeding device A according to the present invention comprises a cover member  51  in which the elevating lever  44  located in the lower limit position is housed. An outer cover for the sheet feeding unit F, located below the tilting tray  42 , is utilized as the cover member  51 . The cover member  51  has a planar portion  52  provided below the tilting tray  42  and having a rectangular opening  53  which is formed in the planar portion  52  and in which the elevating lever  44  is housed. The elevating lever  44  is housed in the opening  53  so as to be able to move into and out of the opening  53 . The elevating lever  44  is housed in the opening  53  when in the lower limit position and projects from the opening  53  toward the rear surface  42   b  of the tilting tray  42  during operation. Thus, during a normal standby condition, the tilting tray  44  is housed in the cover member  51  and prevented from sticking out to the vicinity of the sheet discharging tray even when the sheet feeding tray unit T is caused to pivot upward. Consequently, the elevating lever  44  does not interfere with the operation when a document is taken out of the sheet discharging tray or when a jammed document is removed from the sheet discharging section. 
         [0046]    A projection  42   d  is provided at the leading end of the rear surface  42   b  of the tilting tray  42 . Then, when the elevating cover  44  is housed in the cover member  51 , the projection  42   d  abuts against the planar portion  52  of the cover member  51 . This holds the tilting tray  42  in the loading position. 
         [0047]    The document feeding device A has restraining means for preventing the tilting tray  42  from being shaky on the sheet feeding tray  41  when the sheet feeding tray unit T is caused to pivot upward. As shown in  FIG. 7 , the restraining means comprises an engaging projection  60  projectively formed on the rear surface of the leading end of the tilting tray  42  and serving as an engaging member, a restraining member  61  attached to the cover section  41   b  of the sheet feeding tray  41  and serving as an engaged member. When the sheet feeding tray unit T is caused to pivot, the restraining member  61  engages the engaging projection  60  to prevent a free end of the tilting tray  42  from swinging. A key-like hook  60   a  is formed at a leading end of the engaging projection  60 . In the present embodiment, the engaging projection  60  is formed integrally with the tilting tray  42  using resin. 
         [0048]    The restraining member  61  is such a block-like resin molded article as shown in  FIGS. 7 and 8  and is located in a recess  62  formed in a corner of the cover  41   b  at a front end thereof. In the present embodiment, the restraining member  61  comprises an engaging recess  63 , a housing section  65  which is located behind the engaging recess  63  and in which a compression spring  64  always biasing the restraining member  61  toward the engaging projection  60  is housed, and a slide section  66  that supports the restraining member  61  so that the restraining member  61  is slidable forward and backward relative to the cover section  41   a  of the sheet feeding tray  41 . The engaging recess  63  is composed of an engaging groove  67  into which the engaging projection  60  is fitted and an engaging top wall  68  which is located above the engaging groove  67  and which engages a hook  60   a  at the leading end of the engaging projection  60 . Furthermore, a slot  69  extending in a front-rear direction is formed in the slide section  66 . Two stepped screws  70  arranged in the slot  69  are attached to the cover section  41   b  of the sheet feeding tray  41  to slidably support the restraining member  61 . Moreover, the compression spring  64  is compressed while housed in the housing section  65  with a front end thereof abutting against a front wall  71  of the engaging recess  63  and a rear end thereof abutting against a rib-like projecting wall  72 . That is, as shown in  FIGS. 7A and 8A , when the sheet feeding tray unit T is in the position where a document is delivered from the sheet feeding tray unit T, a vertical wall surface  75  of an outer cover  74  in which the elevating lever  44  is housed presses a front surface  73  of the slide section  66  of the restraining member  61 . This allows the compression spring  64  to be contracted inside the housing section  65 . The restraining member  61  is thus pushed back into the recess  62 . At this time, the hook  60   a  of the engaging projection  60  is fitted into the engaging groove  67  away from the engaging top wall  68  of the engaging recess  62  in the restraining member  61 . On the other hand, as shown  FIGS. 7 and 8B , when the sheet feeding tray unit T pivots upward, the front surface  73  of the slide section  66  of the restraining member  61  is released from the pressure of the vertical wall surface  75  of the outer cover  74 . The elastic force of the compression spring  64  causes the restraining member  61  to slide forward. A front surface  73  of the slide section  66  thus projects out from a front end  76  of the recess  62 . At this time, the hook  60   a  of the engaging projection  60  engages the engaging top wall  68  of the engaging recess  62  in the restraining member  61 . In the present embodiment, the vertical wall surface  75  of the outer cover  74  serves as the pressing member pushing the restraining member  61  back into the recess  62 . However, the pressing member according to the present invention is not limited to this. 
         [0049]    Now, the effects of the restraining means configured as described above will be described below with reference to  FIGS. 7 and 9 .  FIG. 7A  shows that the sheet feeding tray unit T is in the position where a document is loaded on the sheet feeding tray unit T. In this condition, the front surface  73  of the slide section  65  abuts against the vertical wall surface  75  of the outer cover  74  of the sheet feeding unit F to press the restraining member  61  away from the engaging projection  60 , projectively formed on the rear surface of the tilting tray  42 . This pressing operation allows the restraining member  61  to be fitted into the recess  62  in the sheet feeding tray  41  to disengage the hook  60   a  at the leading end of the engaging projection  60  from the engaging top wall  68 , provided in the engaging recess  63  in the restraining member  61 . This enables the tilting tray  42  to be raised or lowered by the elevating lever  44 . 
         [0050]      FIG. 7B  shows that the sheet feeding tray unit T has started pivoting from the loading position. In this case, the front surface  73  of the slide section  66  leaves the vertical wall surface  75  of the outer cover  74  to releases the pressure acting on the vertical wall surface  7 . The elastic force of the compression spring  64  slides the restraining member  61  to cause the front surface  73  of the slide section  66  to project from the front end  76  of the recess  62 . The restraining member  61  thus approaches the engaging projection  60  to engage the leading end hook  60   a  of the engaging projection  60  with the engaging top wall  68 , provided for the engaging recess  63  in the restraining member  61 . 
         [0051]      FIG. 9  shows that the sheet feeding tray unit T has pivoted from the above-described position to the vertical position. While the sheet feeding tray unit T is pivoting toward the vertical position and after the sheet feeding tray unit T is almost set in the vertical condition, the engaging projection  60  remains engaged with the restraining member  61 . Thus, the lower end of the tilting tray  42 , corresponding to a free end, is inhibited from swinging. This prevents the tilting tray  42  from colliding against the sheet feeding tray  41  to make noise. 
         [0052]    Then, the sheet feeding tray unit T is returned from the vertical position in  FIG. 9  to the loading position shown in  FIG. 7A . The front surface  73  of the slide section  66  abuts against the vertical wall surface  75  of the outer cover  74  to slidably move the restraining member  61  away from the engaging projection  60 . The engaging projection  60  is thus disengaged from the restraining member  61  to allow the tilting tray  42  to be raised and lowered again. 
         [0053]    While the tilting tray  42  is elevating, the engaging projection  60  is positioned above the restraining member  61 . This misaligns the hook  60   a  of the engaging projection  60  and the engaging recess  63  in the restraining member  61  in the vertical direction. Thus, even if the sheet feeding tray unit T is caused to pivot to release the restraining member  61  from the pressure to allow the restraining member  61  to project toward the engaging projection  60 , the hook  60  of the engaging projection  60  may not be fitted into the engaging recess  63  in the restraining member  61 . Thus, in this condition, when the sheet feeding tray unit T is caused to pivot, the tilting tray  42  pivots with the lower end thereof unrestrained, together with the sheet feeding tray unit T. This makes the tilting tray  42  shaky. 
         [0054]    According to the present invention, to avoid the above-described situation, a plurality of step-like engaging recesses  63  arranged in a height direction, that is, in a direction in which the tilting tray rises and lowers, may be formed in the restraining member  61  so that if the sheet feeding tray unit T is caused to pivot while the tilting tray  42  is elevating, the engaging projection  60  engages one of the engaging recesses  63 . As previously described, in the present embodiment, while the tilting tray  42  is elevating, the sheet feeding tray unit T is restrained so as not to be able to pivot. 
         [0055]    With the above-described configuration, the restraining means, having the simple structure, allows the tilting tray  42  to rise and lower while the sheet feeding tray unit T is in the position in which the document is delivered from the tray unit T. On the other hand, the restraining means can inhibit the tilting tray  42  from swinging while the sheet feeding tray unit T is pivoting. 
         [0056]    In the above description of the embodiment, the sheet feeding device according to the present invention is applied to the document feeding device by way of example. However, of course, the present invention is not limited to the document feeding device. 
         [0057]    This application claims priority rights from Japanese Pat. App. Nos. 2006-344528 and 2006-344534, both filed on Dec. 21, 2006, the disclosures of which are incorporated by reference. 
         [0058]    While the invention has been explained with reference to specific embodiments thereof, the explanation is illustrative; the scope of the invention is defined only by the appended claims.