Patent Publication Number: US-8973914-B2

Title: Sheet-supply device with a sheet-separation unit having an opening

Description:
The present application is a continuation of co-pending U.S. application Ser. No. 11/209,756, filed Aug. 24, 2005, which claims priority to Japanese Patent Application No. 2004-244308 filed on Aug. 24, 2004, the entire contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a sheet-supply cassette, and an image recording apparatus, such as a printer, a copier, or a facsimile machine, that includes a sheet-supply cassette. 
     2. Discussion of Related Art 
     There has been known a sheet-supply cassette that is employed by an image recording apparatus such as a printer, a copier, or a facsimile machine and supplies, one by one, a plurality of cut recording sheets each as a recording medium. The sheet-supply cassette includes a main member in which a plurality of cut recording sheets are horizontally stacked on each other so that the top one of the stacked cut sheets is fed by a sheet-feed roller pressed against it; and an inclined, sheet-separate plate which is provided in a downstream end portion of the main member as seen in a sheet-feed direction in which each cut sheet is fed. A leading end of each cut sheet being fed is engaged with a front surface of the sheet-separate plate so that the each cut sheet is separated from the other cut sheets and is fed forward. 
     In the above-described conventional sheet-supply cassette, the sheet-separate plate is provided in the downstream end portion of the main member, such that the entirety of the sheet-separate plate is inclined. Therefore, the entire length of the leading end of each cut sheet being fed simultaneously engages the front surface of the sheet-separate plate, thereby receiving too great a frictional resistance. In particular, in the case where a thick cut sheet is fed, the thick cut sheet may not be smoothly curved by the front surface of the sheet-separate plate and accordingly the feeding of the thick cut sheet may fail. 
     In the above-described background, Japanese Patent Application Publication No. 2002-173240 had proposed a sheet-supply cassette including a main member; a plurality of inclined sheet-separate plates that are provided on an inner surface of a side wall of the main member that is located on a downstream end of the main member as seen in a sheet-feed direction, such that the inclined sheet-separate plates are distant from each other in a widthwise direction of each cut recording sheet; and a plurality of pairs of inclined sheet-guide plates which have respective inclined sheet-guide surfaces. Each pair of inclined sheet-guide plates are provided on either side of a corresponding one of the inclined sheet-separate plates in the widthwise direction, and the inclined sheet-guide plates cooperate with each other to guide a plurality of portions of the leading end of each cut sheet that do not contact the inclined sheet-separate plates. Thus, the sheet-supply cassette allows each cut recording sheet to be fed while the leading end portion thereof is smoothly curved in an upward direction without being damaged. 
     However, in the sheet-supply cassette disclosed by the above-indicated document, the inclined sheet-separate plates and the inclined sheet-guide plates are spaced from each other in the widthwise direction of each cut recording sheet. Therefore, the leading end of each cut sheet may be abruptly bent, or may be damaged, at the boundary between each of those plates and a vacant space adjacent to the each plate. 
     SUMMARY OF THE INVENTION 
     In the above-described technical background, the present invention has been developed. It is therefore an object of the present invention to provide a sheet-feed cassette and an image recording apparatus each of which is free of at least one of the above-indicated problems. It is another object of the present invention to provide a sheet-feed cassette and an image recording apparatus each of which does not damage a leading end of each recording sheet being fed and can be easily produced and assembled, 
     According to a first aspect of the present invention, there is provided a sheet-supply cassette, comprising a main member which is open upward and which is adapted to store a plurality of recording sheets which are stacked on each other and each one of which is separated from the other recording sheets, and is fed in a sheet-feed direction, by a sheet feeder; an inclined sheet-separate plate which is provided in a downstream-side portion of the main member as seen in the sheet-feed direction, and which cooperates with the sheet feeder to separate the each recording sheet from the other recording sheets; and a plurality of back-surface support portions which are formed integrally with the downstream-side portion of the main member, such that the back-surface support portions are distant from each other in a perpendicular direction substantially perpendicular to the sheet-feed direction. The inclined sheet-separate plate is detachably attached to the back-surface support portions such that a back surface of the inclined sheet-separate plate is supported by the back-surface support portions. 
     In the sheet-supply cassette in accordance with the first aspect of the present invention, the sheet-separate plate, i.e., the single plate is formed separately from the main member, and subsequently the sheet-separate plate is detachably attached to the back-surface support portions such that the plate is inclined relative to the main member. Therefore, the inclined sheet-separate plate can be easily formed to have an accurate shape. In particular, in the case where the sheet-separate plate has a continuously curved front surface, such as an arcuate surface, the three-dimensional curved surface can be more easily and accurately formed as compared with a case where the three-dimensional curved surface is formed by, e.g., injection molding of a synthetic resin, integrally with the main member. 
     According to a second aspect of the present invention, there is provided an image recording apparatus comprising the sheet-supply cassette according to the first aspect of the present invention; an accommodating portion which accommodates the sheet-supply cassette such that the sheet-supply cassette can be inserted in, and drawn from, the accommodating portion in opposite directions, respectively, that are parallel to the sheet-feed direction; and a snap-action device which causes a snap action at each of (a) a first time when the sheet-supply cassette is inserted in the accommodating portion and (b) a second time when the sheet-supply cassette is drawn from the accommodating portion. 
     Since the image recording apparatus in accordance with the second aspect of the present invention employs the sheet-supply cassette in accordance with the first aspect of the present invention, the image recording apparatus can enjoy the same advantages as the above-described advantages of the sheet-supply cassette. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and optional objects, features, and advantages of the present invention will be better understood by reading the following detailed description of the preferred embodiments of the invention when considered in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view of an image recording apparatus as an embodiment of the present invention; 
         FIG. 2  is a cross-section view of two sheet-supply cassettes of the image recording apparatus; 
         FIG. 3  is a perspective view of an upper one of the two sheet-supply cassettes; 
         FIG. 4  is a perspective view showing a state in which a lower one of the two sheet-supply cassettes is inserted in a second lower case of the image recording apparatus; 
         FIG. 5  is another perspective view, taken from a different angle, that shows the state in which the lower sheet-supply cassette is inserted in the second lower case; 
         FIG. 6  is a perspective view of the lower sheet-supply cassette in a state in which an overall length of the cassette is reduced; 
         FIG. 7  is a perspective view of the lower sheet-supply cassette in a state in which the overall length of the cassette is extended; 
         FIG. 8  is a perspective view of a main portion of the lower sheet-supply cassette in a state in which an auxiliary portion of the cassette is removed; 
         FIG. 9  is a perspective view showing a front surface of an inclined sheet-separate plate for use with the lower sheet-supply cassette; 
         FIG. 10  is a perspective view showing a back surface of the inclined sheet-separate plate; 
         FIG. 11  is an enlarged, cross-section view taken along  11 - 11  in  FIG. 6 ; 
         FIG. 12A  is an enlarged cross-section view taken along  12 A- 12 A in  FIG. 7 ; 
         FIG. 12B  is an enlarged cross-section view taken along  12 B- 12 B in  FIG. 7 ; 
         FIG. 13  is a cross-section view taken along  13 - 13  in  FIG. 4 ; and 
         FIG. 14  is a perspective view showing a state in which the lower sheet-supply cassette is removed from the second lower case. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, there will be described preferred embodiments of the present invention by reference to the drawings.  FIG. 1  shows an image recording apparatus  1  to which the present invention is applied. The image recording apparatus  1  is a so-called “multi-function device (MFD)” that has a printer function, a copier function, a scanner function, and a facsimile-machine function. As shown in the figure, the image recording apparatus  1  includes a housing  2  that is formed of a synthetic resin and includes a first lower case  20  and a second lower case (i.e., a lowermost case)  21  that is connected to the bottom of the first lower case  20 ; an upper sheet-supply cassette  3 A ( FIGS. 2 and 3 ) that is insertable into an opening  20   a  provided in a front-side portion of the first lower case  20 ; and a lower sheet-supply cassette  3 B that is insertable into an opening  21   a  provided in a front-side portion of the second lower case  21 .  FIG. 1  shows a state in which the lower sheet-supply cassette  3 B is inserted in the housing  2  but the upper sheet-supply cassette  3 A is not inserted in the same  2 . In the following description of each of the components, such as the housing  2 , the first lower case  20 , the second lower case  21 , or the upper or lower sheet-supply cassette  3 A,  3 B, a portion, an end, or a side of the each component that is located nearer to the openings  20   a,    21   a  will be referred to as a front portion, a front end, or a front side of the each component, and a portion, an end, or a side of the each component that is located opposite to the openings  20   a,    21   a  will be referred to as a rear portion, a rear end, or a rear side of the each component. 
     In a top portion of the image recording apparatus  1 , there are provided an image reading device, not shown, including an automatic original-sheet feeder  11  that automatically feeds an original sheet bearing an original image, so as to read the original image in a copier or facsimile-machine mode, and an operation panel  14  that is located in front of the image reading device and includes various sorts of operation keys and a liquid-crystal display ( FIG. 1 ). The image reading device additionally includes an original-sheet support glass plate, not shown, that supports, on an upper surface thereof, an original sheet and can be covered by an original-sheet cover member  13  whose rear end is connected via hinges  12  to a rear end of the image reading device such that the cover member  13  is pivotable upward and downward about the hinges  12 . When a user opens the cover member  13  by pivoting the same  13  upward, and places an original sheet on the upper surface of the support glass plate, an image scanner (e.g., a contact image sensor (CIS)) that is provided below the support glass plate is reciprocated in a main scanning direction, i.e., a Y-axis direction in  FIG. 1 , so as to read an original image borne by the original sheet. The Y-axis direction is perpendicular to the drawing sheet of  FIG. 2 . Meanwhile, an original sheet that is placed on an original-sheet supply plate  11  a of the automatic original-sheet feeder  11  is fed downward so that an original image borne by the original sheet is read by the image scanner in an original-image reading area, not shown, that is provided in a left-hand end portion of the support glass plate in  FIG. 1 , and then the original sheet is discharged onto an original-sheet discharge plate  13   a,  i.e., an upper wall of the cover member  13 . 
     Under the operation panel  14  and the image reading device, there are provided a recording portion  7  and a sheet discharging portion  10 , as shown in  FIG. 2 . 
     As shown in  FIG. 2 , the recording portion  7  includes two elongate plate-like guide members  17 ,  18  that are respectively supported by two side walls of a main frame  16  formed of, e.g., a metallic plate and that extend in the Y-axis direction (i.e., the main scanning direction); a carriage  5  that supports a recording head  4  and bridges the two guide members  17 ,  18  such that the carriage  5  is slidable and reciprocateable on the same  17 ,  18 ; a timing belt, not shown, that is provided on an upper surface of the guide member  18 , located on a downstream side in a sheet-feed direction, such that the timing belt extends parallel to the guide member  18 , and that is driven to reciprocate the carriage  5 ; a carriage (CR) motor, not shown, that drives the timing belt; a plate-like platen  19  that is provided below a lower surface of the recording head  4  and supports a recording sheet, P, being fed; and a belt-like encoder strip, not shown, that extends in the Y-axis direction and detects a current position of the carriage  5  in the Y-axis direction. The sheet-feed direction is a direction in which the recording sheet P is fed. The encoder strip has a detection surface in which a plurality of slits are formed at a regular interval in the Y-axis direction, and is provided such that the detection surface is vertical. 
     Two register rollers  22  are provided on an upstream side of the platen  19 , and cooperate with each other to pinch and feed the recording sheet P to a space below the lower surface of the recording head  4 . On a downstream side of the platen  19 , there are provided a spur roller that contacts an upper surface (i.e., a recording surface) of the recording sheet P, and a discharge roller  23  that contacts a lower surface (i.e., a non-recording surface) of the sheet P. The discharging portion  10  discharges the recording sheet P such that the image-recorded surface of the sheet P, recorded by the recording portion  7 , faces upward. The discharging portion  10  is provided above the upper sheet-supply cassette  3 A, such that a sheet-discharge opening communicating with the discharging portion  10  is provided in the front wall of the housing  2 , more specifically described, is located above the opening  20   a.    
     Next, there will be described respective constructions of the two sheet-supply cassettes  3 A,  3 B. First, the upper sheet-supply cassette  3 A that is insertable in the first lower case  20  is described by reference to  FIGS. 2 and 3 . The upper sheet-supply cassette  3 A includes an accommodating portion (i.e., a main portion)  31  that can accommodate a plurality of cut recording sheets P each as a recording medium, such as A4-size sheets, legal-size sheets, letter-size sheets, or postcard-size sheets, such that the sheets P are stacked on each other and respective short sizes of the sheets P extend in a direction (i.e., the direction perpendicular to the drawing sheet of  FIG. 2 , the main scanning direction, or the Y-axis direction) perpendicular to the sheet-feed direction (i.e., a sub-scanning direction or an X-axis direction). The upper sheet-supply cassette  3 A additionally includes, in a front end portion thereof (located nearer to the opening  20   a ), an auxiliary support member  30  that supports respective rear end portions of long cut sheets P, such as legal-size sheets, and is movable relative to the accommodating portion  31  in the X-axis direction.  FIG. 2  shows a state in which the auxiliary support member  30  is held at an extended position thereof where a portion of the support member  30  projects out of the housing  2 . On the other hand, in the case where short cut sheets P, such as A4-size sheets, that can be fully accommodated by the accommodating portion  31 , i.e., do not project out of the first lower case  20  through the opening  20   a  are used, the support member  30  can be retracted into the accommodating portion  31 . 
     In the state in which the auxiliary support member  30  is retracted into the accommodating portion  31  of the upper sheet-supply cassette  3 A, a length of the upper cassette  3 A in the X-axis direction is substantially equal to that of the image reading device or the operation panel  14  in the Y-axis direction. In this state, therefore, the image recording apparatus  1  has a substantially square shape in its plane view, and also has a generally rectangular parallelepiped shape. Thus, when the apparatus  1  is shipped as a final product from a factory, the apparatus  1  can be easily packed, and a size of a package used to pack the same  1  can be reduced. 
     In addition, the upper sheet-supply cassette  3 A has, in a rear end portion thereof (i.e., a right-hand end portion in  FIG. 2 , or a left-hand end portion in  FIG. 3 ), an inclined sheet-separate plate  8  that separates each one cut sheet P from the other cut sheets P. An arm  6   a  is pivotally connected, at an upper end portion thereof to the housing  2  such that the arm  6   a  is pivotable upward and downward, and a sheet-supply roller  6   b  is supported by a lower end portion of the arm  6   a.  The arm  6   a  and the roller  6   b  cooperate with each other to provide a sheet-supply drive portion (i.e., a sheet feeder)  6  that cooperates with the inclined sheet-separate plate  8  to separate and feed, one by one, the cut sheets P stacked on each other in the upper sheet-supply cassette  3 A. The separated sheet P is fed via a first U-turn path (i.e., a first sheet-convey path)  9  that is initially oriented obliquely upward, and then backward to the recording portion  7  provided at a position higher than the upper sheet-supply cassette  3 A. The inclined sheet-separate plate  8  has a convexly curved shape in its plan view in which a middle portion of the plate  8  in a widthwise direction of the sheet P, i.e., the Y-axis direction, swells toward the accommodating portion  31  and opposite end portions of the plate  8  in the Y-axis direction do not swell. On the middle portion of the sheet-separate plate  8 , there is provided a serrate elastic sheet-separate pad  8   a  that engages a leading end of each cut sheet P to promote separation of the each cut sheet P from the other cut sheets P. 
     As shown in  FIGS. 2 ,  4  through  8 , and  14 , the lower sheet-supply cassette  3 B includes a main portion  32  that opens upward and can accommodate a plurality of cut recording sheets P such that the sheets P are stacked on each other; and an auxiliary portion  33  that opens upward, supports respective rear end portions of the sheets P in the sheet-feed direction, i.e., the X-axis direction, and is connected to the main portion  32  such that the auxiliary portion  33  is movable frontward and rearward relative to the main portion  32 . Each of the main portion  32  and the auxiliary portion  33  is formed by injection molding of a synthetic resin. In the present embodiment, the auxiliary portion  33  is located nearer to the opening  21   a  provided in the front wall of the second lower case  21 . The second lower case  21  that opens upward is connected to the bottom of the first lower case  20 , such that the second lower case  21  is joined with, e.g., screws, not shown, to the first lower case  20 . A recess  35  is formed in the respective rear end walls of the first and second lower cases  20 ,  21 , and a second U-turn path (i.e., a second sheet-convey path)  34  that is integral with the first U-turn path  9  is detachably attached to the recess  35 . 
     As shown in  FIG. 8 , the main portion  32  of the lower cassette  3 B includes a bottom plate  36 , two side plates  32   a,    32   b,  and a rear plate  32   c.  The bottom plate  36  has, in a front end portion thereof, a plurality of front stepped portions  36   a,  and one of the front stepped portions  36   a  has, at a position deviated by an appropriate distance in one direction from the middle portion of each cut sheet P in the widthwise direction thereof (i.e., the Y-axis direction) perpendicular to the sheet-feed direction, a plurality of engaging grooves  37   a,    37   b  as a plurality of first engaging portions that respectively define a plurality of engagement positions (described in detail later) of the auxiliary portion  33  that correspond to different lengths of a plurality of sorts of cut sheets P in the sheet-feed direction. The grooves  37   a,    37   b  are distant from each other by an appropriate distance in the X-axis direction. 
     An inclined sheet-separate plate  39 , shown in  FIGS. 9 and 10 , that is constituted by a single plate is supported, at a back surface thereof, by a plurality of first back-surface support portions  40  each having a trapezoidal shape in its side view, and a plurality of second back-surface support portions  41 . The above-described legal-size sheets or letter-size sheets have a width of 215.9 mm, and the inclined sheet-separate plate  39  has a length greater than the width of those sheets P. The first and second back-surface support portions  40 ,  41  are provided in front of the rear wall  32   c  of the main portion  32 , such that the support portions  40 ,  41  are distant from each other by respective appropriate distances in the Y-axis direction. As shown in  FIG. 7 , the second back-surface support portions  41  are located nearer to opposite ends of the rear wall  32   c  in the widthwise direction of each cut sheet P than the first back-surface support portions  40 . Each of the second support portions  41  has an engaging groove  42  that extends from an upper end thereof in a downward direction. The two first back-surface support portions  40  are located nearer to a middle portion of the rear wall  32   c  in the widthwise direction of each cut sheet P, and are each constituted by a rib having a substantially triangular shape in its side view. The first back-surface support portions  40  have respective inclined surfaces  40   a  that engage and support a plurality of reinforcing ribs  47  ( FIG. 10 ) of the inclined sheet-separate plate  39 . 
     In the present embodiment, the two first back-surface support portions  40  are located at respective positions that are symmetrical with each other with respect to a centerline of the main portion  32  that is parallel to the sheet-feed direction, i.e., is perpendicular to a widthwise direction of the main portion  32  and that are nearer, in the widthwise direction, to the centerline than the respective positions where the four second back-surface support portions  41  are located and which are also symmetrical with each other with respect to the centerline. 
     The inclined sheet-separate plate  39  is formed by injection molding of a synthetic resin. The inclined plate  39  has, in the back surface thereof, a plurality of engaging claws  43  each of which is formed integrally with the remaining portion of the inclined plate  39  and has a generally T-shaped cross section. The four engaging claws  43  can engage the respective engaging grooves  42  of the four second back-surface support portions  41 , when the inclined sheet-separate plate  39  is moved, in a downward direction, toward the main portion  32  by a hand of a person. In addition, as shown in  FIGS. 9 and 10 , the inclined sheet-separate plate  39  has, in a middle portion thereof in a lengthwise direction thereof (i.e., the Y-axis direction or the widthwise direction of each cut sheet P), a window hole  45  through which an elongate, serrate, elastic sheet-separate pad  44  ( FIG. 4 ) as a sheet-separate portion that is provided on the back surface of the inclined plate  39  is exposed to the front surface of the same  39 . Moreover, as shown in  FIG. 10 , the inclined sheet-separate plate  89  has, in the back surface thereof, an attachment case (i.e., a holder case)  46  that is formed integrally with the remaining portion of the inclined plate  39  and accommodates a support member supporting the elastic pad  44 . Each of the reinforcing ribs  47  is partly formed on an outer surface of a corresponding one of the side walls of the attachment case  46 , and is partly formed on the back surface of the inclined plate  39 . As described above, the reinforcing ribs  47  can engage the respective inclined surfaces  40   a  of the first back-surface support portions  40 . Thus, the inclined sheet-separate plate  39  is detachably attached to the first and second back-surface support portions  40 , without using a tool. 
     An enveloping surface that envelopes the respective front surfaces of the first and second back-surface support portions  40 ,  41  that are opposed to the back surface of the inclined sheet-separate plate  39  is convexly curved such that a middle portion of the enveloping surface in the widthwise direction of each cut sheet P projects from opposite end portions thereof toward the cut sheets P stored in the main portion  32 , so that when each cut sheet P is fed forward, widthwise opposite end portions of the cut sheet P contact the opposite end portions of the enveloping surface, at a timing somewhat later than a timing when the widthwise middle portion of the cut sheet P contacts the widthwise middle portion of the enveloping surface. 
     Therefore, if the inclined sheet-separate plate  39  is moved downward toward the second back-surface support portions  41  such that the engaging claws  43  (i.e., engaging projections as first engaging portions) provided on the back surface of the plate  39  engage the respective engageable grooves  42  (i.e., engaging recesses as second engaging portions) of the second support portions  41 , and such that the reinforcing ribs  47  provided on either side of the attachment case  46  engage the inclined surfaces  40   a  of the first back-surface support portions  40 , then the front surface of the plate  39  that is opposed to each cut sheet P is also convexly curved like an arc, in its plan view, such that a middle portion of the front surface in the widthwise direction of each cut sheet P projects from opposite end portions thereof toward the cut sheets P stored in the main portion  32 , so that when each cut sheet P is fed forward, widthwise opposite end portions of the cut sheet P contact the opposite end portions of the enveloping surface, at a timing somewhat later than a timing when the widthwise middle portion of the cut sheet P contacts the widthwise middle portion of the enveloping surface. 
     In a modified form of the present embodiment, the inclined sheet-separate plate  39  may be formed of an elastically deformable, semi-hard synthetic resin to have a flat shape. In this case, the engaging claws  43  provided on the back surface of the plate  39  are engaged with the respective engageable grooves  42  of the second back-surface support portions  41 , by elastically deforming the lengthwise opposite end portions of the plate  39  in respective directions away from the widthwise opposite end portions of each cut sheet P. In this state, the respective inclined surfaces  40   a  of the first back-surface support portions  40  located in the middle portion of the rear side wall  32   c  in the widthwise direction of each cut sheet P engage the reinforcing ribs  47  of the plate  39 , such that the inclined surfaces  40   a  press back the reinforcing ribs  47 . In this case, too, the front surface of the inclined sheet-separate plate  39  is convexly curved like an arc, in its plan view. 
     Thus, the middle portion of the front surface of the inclined sheet-separate plate  39  in the widthwise direction of each cut sheet P projects such that the middle portion of the front surface contacts a leading end of the cut sheet P being fed, prior to the opposite end portions of the front surface, and the opposite end portions subsequently contact the leading end. Thus, the elastic sheet-separate pad  44  as the frictional member that is located in the lengthwise middle portion of the plate  39  can surely separate the cut sheets P, one by one. In addition, since the inclined sheet-separate plate  39  does not simultaneously contact all portions of the leading end of each cut sheet P, a frictional resistance produced between the each cut sheet P and the plate  39  lowers, and accordingly the each cut sheet P can be smoothly separated from the other cut sheets P, that is, jamming of the cut sheets P can be effectively prevented. 
     In each of the above-described embodiments, the inclined sheet-separate plate  39  is formed independent of the main portion  32  of the lower sheet-supply cassette  3 B, and then the plate  39  is assembled with the first and second back-surface support portions  40 ,  41 . Therefore, the three-dimensional convexly curved shape (i.e., the arcuate shape) of the front surface of the plate  39  can be considerably easily formed. 
     In addition, since the first and second back-surface support portions  40 ,  41  are provided at the respective positions that are symmetrical with each other with respect to the centerline of the main portion  32  that is perpendicular to the widthwise direction of each cut paper P, the arcuately curved front surface of the inclined sheet-separate plate  39  can be easily formed symmetrically with respect to the centerline. Consequently the frictional resistance is produced between the front surface of the plate  39  and the leading end of each cut sheet P being fed, symmetrically with respect to the centerline, and accordingly the cut sheet P can be fed without being deflected and the jamming of the cut sheets P can be effectively prevented. 
     Moreover, since the inclined sheet-separate plate  39  is formed independent of the main portion  32  of the lower sheet-supply cassette  3 B, the sheet-separate pad  44  can be easily attached to the pad-holding case  46  provided on the back surface of the plate  39 . 
     As shown in  FIGS. 2 ,  6 ,  7 , and  11 , the auxiliary portion  33  includes a front wall  50  that can close the opening  21   a  of the front wall of the second lower case  21 ; two side support plates  51   a  that extend horizontally from a lower portion of the front wall  50  and cooperate with each other to support the respective rear end portions of the cut sheets P; a middle support plate  51   b  that is located between the two side support plates  51   a,  extend horizontally from the lower portion of the front wall  50 , and cooperate with the two side support plates  51   a  to support the respective rear end portions of the cut sheets P; a plate-like operable portion  52  that stands upright so as to be opposed to an inner surface of the front wall  50 ; and a support plate  53  that extends from a lower end of the operable portion  52 , in the sheet-feed direction. As shown in  FIG. 11 , the support plate  53  has, in a free end portion thereof, an engaging claw  54  as a second engaging portion that extends downward; and the front wall  50  has, on an outer side thereof a handle portion  55  opening downward. Respective base portions of the operable portion  52  and the support plate  53  are integrally formed with an elastically deformable connection portion  52   a  that integrally protrudes from the lower portion of the front wall  50  and is elastically deformable upward and downward. Thus, in the auxiliary portion  33 , the front wall  50  is integrally formed with the operable portion  52  and the support plate  53  including the engaging claw  54  that can selectively engage an appropriate one of the engaging grooves (i.e., the first engaging portions)  37   a,    37   b  that are formed in the main portion  32  such that the grooves  37   a,    37   b  are distant from each other by an appropriate distance in the sheet-feed direction. 
     The two side support plates  51   a,  the middle support plate  51   b,  and the support plate  53  of the auxiliary portion  33  are accommodated by the front low stepped portions  36   a  of the bottom plate  36  of the main portion  32 , such that respective upper surfaces of the plates  51   b ,  51   b,    53  are flush with an upper surface of the bottom plate  36 . Therefore, the lowermost one of the cut sheets P stacked in the lower sheet-supply cassette  3 B is supported by a flat surface defined by the respective upper surfaces of the plates  51   b,    51   b,    53 ,  36 . 
     The auxiliary portion  83  additionally has two guide plates  57  that are located outside the two side support plates  51  a, respectively, are formed integrally with the same  51   a , respectively, are short in height, and extend in the sheet-feed direction. As shown in  FIGS. 12A and 12B , the two guide plates  57  are slideably insertable into two guide grooves  58 , respectively, which are formed in the two side walls  32   a,    32   b  of the main portion  32 , respectively, and each of which opens downward and frontward. Each of the two side walls  32   a,    32   b  has, on an inner surface thereof, a plurality of hold-down portions  59  that engage an upper surface of a corresponding one of the two guide plates  57 . Therefore, even if the auxiliary portion  33  is largely drawn or extended from the main portion  32 , as shown in  FIG. 7 , the front wall  50  can be effectively prevented from being tilted downward. In other words, the respective upper surfaces of the two side support plates  51   a,  the middle support plate  51   b,  and the support plate  53  are kept flush with the upper surface of the bottom plate  36  of the main portion  32 .  FIGS. 12A and 12B  show only the guide groove  58  and the hold-down portions  59  formed in the left-hand side wall  32   b  as seen in  FIG. 7 . 
     A sheet-rear-end guide member  56  as a positioning member that engages the respective rear ends of the cut sheets P and thereby positions the same P in the sheet-feed direction, is attached to an upper surface of the middle support plate  51   b  of the auxiliary portion  33 , such that the guide member  56  is slidable in the sheet-feed direction with the user&#39;s hand while the hand feels clicks. The bottom plate  36  of the main portion  32  additionally has two rear low stepped portions  36   b  that accommodate two sheet-side-end guide members  60 , respectively, that guide two widthwise opposite sides of each of the cut sheets P, respectively, and cooperate with each other to position the each cut sheet P symmetrically with respect to the centerline of the main portion  32 , in the widthwise direction of the each cut sheet P. To this end, the two guide members  60  are slidable in the widthwise direction of the main portion  32 . 
     The lower sheet-supply cassette  3 B constructed as described above is used in the following manner: For example, when the A4-size cut sheets P are stacked and stored in the lower cassette  3 B such that the lengthwise direction of the cut sheets P is parallel to the sheet-feed direction, first, the thumb of the user&#39;s hand is applied to the outer surface of the front wall  50 , and the index and middle fingers are applied to the plate-like operable portion  52 , and then an external force is so applied as to decrease the distance between the inner surface of the front wall  50  and the upper portion of the operable portion  52 . Consequently the connection portion  52   a  that integrally protrudes from the lower portion of the front wall  50  and is elastically deformable upward and downward is elastically deformed upward, so that the free end portion of the support plate  53  is moved upward, as indicated at two-dot chain line in  FIG. 11 . Thus, the engaging claw  54  is disengaged from one engaging groove  37   b  located on the upstream side of the other engaging groove  37   a  as seen in the sheet-feed direction. In this state, the auxiliary portion  33  is pushed into the front end portion of the main portion  32 . Then, the external force being applied to the operable portion  62  is released. Once the engaging claw  54  is engaged with the other engaging groove  37   a  located on the downstream side in the sheet-feed direction, the lower cassette  3 B is kept in the state in which the overall length thereof in the sheet-feed direction is decreased. 
     On the other hand, when the legal-size cut sheets P longer than the A4-size cut sheets P are stored in the lower cassette  3 B, the auxiliary portion  38  is operated in reverse. More specifically described, first, an external force is applied to the operable portion  52 , so as to disengage the engaging claw  54  provided in the free end portion of the support plate  53 , from the downstream engaging groove  37   a.  In this state, the auxiliary portion  33  is drawn from the front end portion of the main portion  32 , so that the engaging claw  54  engages the upstream engaging groove  37   b.  Thus, the lower cassette  3 B is kept in the state in which the overall length thereof is increased. 
     As shown in  FIG. 11 , the bottom plate  36  of the main portion  32  has two gentle-slope surfaces  61   a,    61   b  that are located between the two engaging grooves  37   a,    37   b  such that the two gentle-slope surfaces  61   a,    61   b  are opposed to each other in the sheet-feed direction. Therefore, in the state in which the engaging claw  54  is disengaged from one of the two engaging grooves  37   a,    37   b,  the auxiliary portion  33  can be drawn or pushed relative to the main portion  32 , without needing the application of external force to the operable portion  52 . Thus, the engaging claw  54  can be smoothly engaged with the other engaging groove  37   a,    37   b.    
     As described above, the operable portion  52  is provided at the position deviated by the appropriate distance in one direction from the widthwise middle portion of the lower sheet-supply cassette  3 B. This arrangement is convenient for the user to move the auxiliary portion  33  frontward and rearward by applying, with one hand, the external force to the operable portion  52  and grasping, with the other hand, the front wall  50 , i.e., the handle portion  55  thereof. In addition, the front wall  50  of the auxiliary portion  33  has, in a lower end portion thereof, a support leg portion  62  that is formed integrally with the remaining portion of the front wall  50  and supports the auxiliary portion  33  at substantially the same height as a height at which the main portion  32  is supported by the second lower case  21 . This arrangement assures that when the auxiliary portion  33  is moved frontward or rearward, the respective upper surfaces of the two side support plates  51   a,  the middle support plate  51   b,  and the support plate  53  can be kept flush with the upper surface of the bottom plate  36  of the main portion  32 . Thus, the cut sheets P stacked in the lower cassette  3 B are effectively prevented from being bent or wrinkled. 
     As shown in  FIGS. 2 ,  4 ,  5 , and  13 , the second lower case  21  that accommodates the lower sheet-supply cassette  3 B has a plurality of reinforcing beams  63   a,    63   b,    63   c  that extend in a a widthwise direction of the second case  21  that is perpendicular to the sheet-feed direction, and connect between respective upper portions of widthwise opposite end portions of the lower case  21 . The first beam  63   a  as the most downstream one of the three beams  63   a,    63   b,    63   c  as seen in the sheet-feed direction has, on a lower surface thereof, a plurality of guide ribs  64  which are formed integrally with the remaining portion of the first beam  63   a  and each of which extends in the sheet-feed direction and additionally functions as a reinforcing member. Owing to the guide ribs  64 , even in the case where a large number of cut sheets P up to, e.g., about 250 sheets P are stacked in the lower cassette  3 B, a sheet-feed roller  65   b  of a sheet feeding device  65  can be rotated to separate and feed the sheets P, one by one, without causing jamming of each sheet P with the beam  63   a.    
     As shown in  FIG. 14 , the second lower case  21  has an insertion passage  70  in and from which the lower sheet-supply cassette  3 B is inserted and drawn. The second lower case  21  has two first restrictor projections  71  (only one projection  71  is shown in the figure) which project into the insertion passage  70  and each of which has a generally triangular shape in its plan view. The restrictor projections  71  are provided at respective positions that are intermediate in the direction of insertion of the lower cassette  3 B and are opposed to the respective outer surfaces of the two side walls  32   a,    32   b  of the main portion  32 . In addition, as shown in  FIGS. 6 through 8 , the two side walls  32   a,    32   b  of the main portion  32  have, on the respective outer surfaces thereof, two second restrictor projections  72  (only one projection  72  is shown in the figures) each of which has a generally triangular shape in its plan view and which are provided at respective positions that are intermediate in a lengthwise direction of the main portion  32 , i.e., the direction of insertion of the lower cassette  3 B. When the lower cassette  3 B is inserted in the insertion passage  70 , the second restrictor projections  72  thereof temporarily engage, and climb over, the first restrictor projections  71  of the second case  21 , respectively. Thus, the first and second restrictor projections  71 ,  72  cooperate with each other to provide a snap-action device, or a pair of gap reducing devices. Owing to the snap-action device or the gap reducing devices, the user&#39;s hand can feel a click when inserting or drawing the lower cassette  3 B in or from the second case  21 . It is preferred that the user&#39;s hand may feel the click when an almost entire portion of the lower cassette  3 B has been inserted in the insertion passage  70  of the second case  21 . To this end, the first restrictor projections  71  are provided at respective positions near to the opening  21   a  of the second case  21 , and the second restrictor projections  72  are provided at respective positions near to the front wall  50  of the lower cassette  3 B. 
       FIG. 4  shows a switching device  67  that selectively transmits an output power of a drive source, not shown, to either one of a first power transmission gear, not shown, for the sheet feeding device  65  of the lower sheet-supply cassette  3 B, a second power transmission gear, not shown, for the sheet feeding device  6  of the upper sheet-supply cassette  3 A, and a third power transmission gear for a maintenance device, not shown. The switching device  67  includes three gears  68   a,    68   b,    68   c  with either one of which a drive gear  69  is selectively engaged according to an amount of movement of the carriage  5  in a rightward direction in  FIG. 4 . 
     While the present invention has been described in its preferred embodiments, it is to be understood that the present invention is by no means limited to the details of the described embodiments but may otherwise be embodied. 
     For example, in each of the above-described embodiments, the image recording apparatus  1  employs the plurality of sheet-supply cassettes  3 A,  3 B. However, the principle of the present invention is applicable to an image recording apparatus employing a single sheet-supply cassette only. 
     It is to be understood that the present invention may be embodied with various changes, modifications, and improvements that may occur to a person skilled in the art without departing from the spirit and scope of the invention defined in the appended claims.