Abstract:
An object of the present invention is to provide an image forming apparatus in which various kinds of sheets can be used and which can be made compact and reduce the number of parts.  
     The present invention provides an image forming apparatus for forming an image on a sheet, which has a sheet feeding cassette, first sheet feeding means, and image forming means, wherein the sheet feeding cassette is provided with second sheet feeding means for feeding out a sheet contained in a second sheet storing portion different from the first sheet storing portion of the sheet feeding cassette.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an image forming apparatus such as a copying machine, a printer and the like, and more particularly, it relates to an apparatus for supplying a sheet to image forming means.  
           [0003]    2. Related Background Art  
           [0004]    In some conventional image processing apparatuses such as copying machines, printers and the like, sheets on which images are to be formed are contained in a sheet feeding cassette which can be drawn from a main body of the apparatus, and the sheets are picked up one by one by means of a sheet feeding mechanism provided in the main body of the apparatus, and the picked-up sheet is supplied to image forming means.  
           [0005]    By the way, in case of an image forming apparatus in which various kinds of sheets are required to be used, there may be provided a multi sheet feeding apparatus in which, independently from the sheet feeding cassette, various kinds of sheets can be set by manual insertion and which includes a sheet storing portion for stacking and containing sheets to be set, and sheet feeding means such as a pick-up roller for feeding out the sheet stacked and contained in the sheet storing portion to image forming means.  
           [0006]    However, in a conventional image forming apparatus having such a multi sheet feeding apparatus, the multi sheet feeding apparatus may prevent compactness of the image forming apparatus itself since it (including the sheet feeding means) assumes a large space within the image forming apparatus. Further, the number of parts is increased.  
           [0007]    Incidentally, in order to make the multi sheet feeding apparatus more compact, for example, so-called manual sheet feed may be effected by providing a guide member on a part of the sheet feeding cassette in place of the sheet feeding means and by feeding the sheet set on the guide member one by one. However, with this arrangement, the sheets cannot be fed continuously, and, thus, this arrangement is unsuitable for use with an image forming apparatus installed under a net-worked environment.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention is made in consideration of the above circumstances, and an object of the present invention is to provide an image forming apparatus in which various kinds of sheets can be used and which can be made compact and reduce the number of parts.  
           [0009]    The present invention provides an image forming apparatus for forming an image on a sheet, comprising a sheet feeding cassette containing sheets and mounted to a main body of the apparatus for a drawing movement, first sheet feeding means for feeding out the sheet from a first sheet storing portion provided in the sheet feeding cassette, and image forming means for forming an image on the sheet fed out by the first sheet feeding means, wherein the sheet feeding cassette is provided with second sheet feeding means for feeding out a sheet contained in a second sheet storing portion different from the first sheet storing portion of the sheet feeding cassette. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a schematic constructural view of a printer as an example of an image forming apparatus according to an embodiment of the present invention;  
         [0011]    [0011]FIG. 2 is a view showing a condition that a sheet feeding cassette of the printer of FIG. 1 is drawn;  
         [0012]    [0012]FIG. 3 is a front view of multi sheet supplying means provided on the sheet feeding cassette of FIG. 1;  
         [0013]    [0013]FIG. 4 is a plan view of a gear train from a driving source to various rollers;  
         [0014]    [0014]FIG. 5 is a perspective view showing a condition that a driving force is transmitted from the driving source;  
         [0015]    [0015]FIG. 6 is a perspective view showing a condition that the driving force from the driving source is transmitted to a multi sheet supplying diving arm;  
         [0016]    [0016]FIG. 7 is an enlarged perspective view of a rotational force interrupting portion;  
         [0017]    [0017]FIG. 8 is a view for explaining operation of a driving rotary lever and the multi sheet supplying driving arm;  
         [0018]    [0018]FIG. 9 is a graph showing a sequence when the sheets are supplied from the multi supplying means;  
         [0019]    [0019]FIG. 10 is a table showing a sequence when the sheets are supplied from the multi supplying means;  
         [0020]    [0020]FIG. 11 is a perspective view showing a condition that a sensor substrate is installed;  
         [0021]    [0021]FIG. 12 is a perspective view of the sensor substrate having detecting sensors;  
         [0022]    [0022]FIG. 13 is a perspective view showing a condition that a sensor substrate and the like are installed;  
         [0023]    [0023]FIG. 14 is a view for explaining a construction of the sheet feeding cassette;  
         [0024]    [0024]FIG. 15 is a view for explaining another construction of the sheet feeding cassette; and  
         [0025]    [0025]FIG. 16 is a view for explaining other construction of the sheet feeding cassette. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]    The present invention will now be fully explained in connection with embodiments thereof with reference to the accompanying drawings.  
         [0027]    First of all, a color printer (image forming apparatus)  9  having sheet supplying means  8  will be explained with reference to FIG. 1. Incidentally the present invention can be applied to not only the color printer but also an image forming apparatus such as a copying machine, a facsimile apparatus and combination thereof.  
         [0028]    In FIG. 1, the color printer  9  comprises a main body  10  of the apparatus including the sheet supplying means  8  and image forming means  12  for effecting image process on a sheet fed out from the sheet supplying means  8 . The sheet supplying means  8  includes sheet feeding cassette supplying means  20  capable of feeding-in a sheet from a sheet feeding cassette containing sheets, and multi supplying means  21  capable of feeding-in a sheet manually set by an operator, so that the sheet is supplied to the image forming means  12  selectively from the sheet feeding cassette supplying means  20  or the multi supplying means  21 .  
         [0029]    The image forming means  12  includes four photosensitive drums  1   a,    1   b,    1   c,    1   d  corresponding to four colors as magenta, cyan, yellow and black, charging means  2   a,    2   b,    2   c,    2   d  for uniformly charging surfaces of the respective photosensitive drums, exposing means  3   a,    3   b,    3   c,    3   d  for forming electrostatic latent images on the respective photosensitive drums by illuminating laser beams in response to respective image informations, developing means  4   a,    4   b,    4   c,    4   d  for visualizing the electrostatic latent images as toner images by adhering toners to the electrostatic latent images, transfer rollers  5   a,    5   b,    5   c,    5   d  as transfer means for transferring the toner images on the photosensitive drums onto the sheet, and cleaning means  6   a,    6   b,    6   c,    6   d  for removing toners remaining on the respective photosensitive drums after the transferring. The charging means and the developing means are disposed in order in a rotational direction around the corresponding photosensitive drum.  
         [0030]    The photosensitive drums  1   a,    1   b,    1   c,    1   d,  charging means  2   a,    2   b,    2   c,    2   d,  developing means  4   a,    4   b,    4   c,    4   d  and cleaning means  6   a,    6   b,    6   c,    6   d  are integrally incorporated into cartridge units to form process cartridges  7   a,    7   b,    7   c,    7   d,  respectively.  
         [0031]    The sheet supplied from the sheet supplying means  8  is conveyed from an upstream side (downward direction in FIG. 1) toward a downstream side (upward direction in FIG. 1) in a sheet conveying direction. Meanwhile, a magenta color toner image, a cyan color toner image, an yellow color toner image and a black color toner images are successively transferred onto the sheet in a superimposed fashion, thereby forming a color image. Thereafter, the image is fixed to the sheet by a fixing unit  14 , and, thereafter, the sheet is discharged onto a discharge tray  13 .  
         [0032]    Further, when images are formed on both surfaces of a sheet, the sheet having one surface on which the image was formed is turned over (surface-reversed) by a pair of discharge rollers  15  to direct the sheet into a reverse path  16 , and an image is formed on a second surface of the sheet by the image forming means  12 . Thereafter, the sheet is discharged onto the discharge tray  13 .  
         [0033]    Next, the sheet supplying means  8  will be described with reference to FIGS. 2 and 3. Incidentally, FIG. 3 is a view of the multi supplying means  21 , looked at from a side of the stacked sheets to be supplied.  
         [0034]    There is provided a sheet feeding cassette  22  containing the sheets and mounted to a lower portion of the main body  10  of the apparatus for drawing movement. The sheet feeding cassette  22  is provided with a cassette tray  23  as first sheet containing portion for stacking and containing sheets S, separating means (not shown such as a separation claw or a separation pad for separating the sheets one by one, and one roller  24   a  of a pair of conveying rollers, and the cassette tray  23 , separating means and roller  24   a  constitute the sheet feeding cassette supplying means  20 . Further, at an end of a drawing side of the sheet feeding cassette  22 , there is provided the multi supplying means  21  having a multi tray  25  as a second sheet containing portion independently from the cassette tray  23 .  
         [0035]    Further, the main body  10  of the apparatus includes a pick-up roller  26  as first sheet feeding means for feeding out the sheet(s) stacked and contained on the cassette tray  23 , and the other roller  24   b  of the pair of conveying rollers, and the pick-up roller  26  is driven by a driving portion which will be described later. The sheets S contained in the cassette tray  23  are picked up by the pick-up roller  26  and then are separated one by one by means of the separating means. The separated sheet is conveyed by the pair of conveying rollers  24   a,    24   b  to be fed to the image forming means  12 .  
         [0036]    On the other hand, the multi supplying means  21  integral with the cassette tray  23  includes a multi tray  25  on which a sheet stack or bundle is manually set by the operator, a pick-up roller  27  as second sheet feeding means for feeding out the sheets stacked on the multi tray  25 , a separation pad  28  for separating the sheets S fed out by the pick-up roller  27  one by one, and a pair of conveying rollers  29  for conveying the separated sheet. Incidentally, the multi tray  25  is provided with side guides (not shown) for regulating lateral edges of the sheets S.  
         [0037]    As shown in FIG. 3, the multi supplying means  21  includes a lifting/lowering plate  31  for supporting leading end portions of the sheets stacked on the multi tray  25  and for urging the sheets against the pick-up roller  27 . A cam  32  for controlling lifting/lowering of the lifting/lowering plate  31  is attached to a rotary shaft  30  of the pick-up roller  27 . With this arrangement, when the pick-up roller  27  is rotated by rotation of the rotary shaft  30 , the lifting/lowering plate  31  is lifted by the action of the cam  32  attached to the rotary shaft  30  and by the action of a synchronous plate  33  for transmitting the motion of the cam  32  to the lifting/lowering plate  31 , with the result that the leading end portions of the sheet stack S is urged against the pick-up roller  27 .  
         [0038]    The sheets S are separated one by one by cooperation between the pick-up roller  27  and the separation pad  28 , and the separated sheet is conveyed by the pair of conveying rollers  29  to be supplied to the image forming means  12 .  
         [0039]    Incidentally, as mentioned above, the sheet feeding cassette  22  is detachably mountable to the main body  10  of the apparatus. When the sheets S are contained in the cassette tray  23 , the sheet feeding cassette  22  is drawn from the main body  10  of the apparatus in a direction shown by the arrow in FIG. 2, and, after the sheets S are contained, the sheet feeding cassette  22  is pushed or retracted into the main body  10  of the apparatus.  
         [0040]    By the way, the pick-up roller  27  and the conveying roller pair  29  of the multi supplying means  21  are driven by driving means provided in the main body  10  of the apparatus. By providing the driving means for driving the multi supplying means  21  within the main body  10  of the apparatus in this way, in other words, by not providing the driving means on the multi supplying means  21 , the multi supplying means  21  can be made more compact, thereby making the printer itself more compact.  
         [0041]    Next, a construction of drive transmitting means for causing a driving source provided in the main body  10  of the apparatus to drive the sheet supplying means  8  will be explained with reference to FIGS.  4  to  8 . Incidentally, in the illustrated embodiment, the drive transmitting means is designed to also drive the pickup roller  26  of the cassette supplying means  20  and the conveying roller  24   a  provided on the sheet feeding cassette  22 .  
         [0042]    As shown in FIGS. 4 and 5, a sheet supplying diving gear train  82  of the sheet supplying means  8  serves to selectively transmit a driving force from a stepping motor  811  of the driving source to the pick-up roller  26  for supplying the sheet from the cassette tray  23 , a registration roller  834 , a driving rotary lever  851  for operating a multi sheet supplying driving arm  852 , and the pick-up roller  27  for supplying the sheet from the multi tray  25 .  
         [0043]    The sheet supplying driving gear train  82  is constituted by a sheet feeding cassette pick-up roller rotational force transmitting portion (first rotational force transmitting means)  824  for transmitting the driving force to the pick-up roller  26  of the cassette supplying means  20 , and a multi pick-up roller rotational force transmitting portion (second rotational force transmitting means)  847 .  
         [0044]    The multi pick-up roller rotational force transmitting portion (second rotational force transmitting means)  847  is constituted by a gear train including a starting gear  812 , idle gears  813 ,  814 , a driving shaft  815 , a one-way bearing  817 , a driving gear  816 , idle gears  831 ,  841 ,  842 ,  843  and a multi sheet non-toothed gear (second non-toothed gear)  844 .  
         [0045]    Further, the sheet feeding cassette pick-up roller rotational force transmitting portion (first rotational force transmitting means)  824  is constituted by a gear train including the starting gear  812 , the idle gears  813 ,  814 , the driving shaft  815 , the one-way bearing (one-way clutch)  817 , the driving gear  816 , an idle gear  821  and a sheet feeding cassette sheet supplying non-toothed gear (first non-toothed gear)  822 .  
         [0046]    Next, a mechanism for controlling driving transmission of the pick-up roller  27  of the multi supplying means  21  will be explained with reference to FIG. 7.  
         [0047]    A multi sheet supplying driving arm (engaging/disengaging arm)  852  is rockably supported on a shaft of the idle gear  841  and is provided at its end with an engaging portion  852   a  engaged by an engaged portion  844   a  provided on the multi sheet supplying non-toothed gear  844  thereby to regulate rotation of the multi sheet supplying non-toothed gear  844 . Normally, the multi sheet supplying driving arm  852  is rotatingly biased by a multi sheet supplying driving arm spring  853  toward a direction along which the engaging portion  852   a  is engaged by the engaged portion  844   a.  In a condition that the multi sheet supplying non-toothed gear  844  is regulated, since a non-toothed portion of the multi sheet supplying non-toothed gear  844  is opposed to the idle gear  843 , the driving force is not transmitted. A multi sheet supplying non-toothed gear spring (rotation biasing means)  845  serves to rotate the multi sheet supplying non-toothe gear  844  to be engaged by the idle gear  843  when the regulation of the multi sheet supplying non-toothed gear  844  is released. Incidentally, the multi sheet supplying driving arm (engaging/disengaging arm)  852 , multi sheet supplying non-toothe gear  844 , multi sheet supplying non-toothed gear spring (rotation biasing means)  845 , multi sheet supplying driving arm spring  853 , engaged portion  844   a  and engaging portion  852   a  constitute a rotational force interrupting (blocking) portion (rotational force interrupting means).  
         [0048]    The driving gear  816  and the driving rotary lever (operating lever)  851  are provided on the driving shaft  815  for opposite rotational movements by means of one-way bearings (one-way clutches)  817 ,  818 . Incidentally, the one-way bearing (one-way clutch)  818  and the driving rotary lever (operating lever)  851  constitute an operation switching portion (operation switching means)  855 .  
         [0049]    Next, the operation of the drive transmission will be described.  
         [0050]    Normally, as shown in FIG. 5, when the stepping motor  811  is rotated in a direction shown by the arrow in FIG. 5, a rotational force of the motor  811  is transmitted to the driving gear  816  through the starting gear  812 , idle gear  813 ,  814 , driving shaft  815  and one-way bearing (one-way clutch)  817 , thereby rotating the driving gear  816  in a direction shown by the arrow in FIG. 5. However, the driving rotary lever  851  is not rotated and remains stationary due to the presence of the one-way bearing (one-way clutch)  818 .  
         [0051]    By the driving gear  816 , the sheet feeding cassette sheet supplying non-toothed gear  822  to which the shaft of the pick-up roller  26  is secured is rotated via the idle gear  821 , thereby rotating the pick-up roller  26 . At the same time, by the driving gear  816 , a registration roller gear  833  is rotated via the idle gear  831 ,  832 , thereby rotating the registration roller  834 .  
         [0052]    Since a non-toothed portion  822   a  is formed on the sheet feeding cassette sheet supplying non-toothed gear  822 , when the sheet feeding cassette sheet supplying non-toothed gear  822  is rotated by about one revolution, the pick-up roller  26  is stopped. Incidentally, the sheet feeding cassette sheet supplying non-toothed gear  822  is normally held by a solenoid (not shown) so that the non-toothed portion  822   a  is opposed to the idle gear  821 . When it is desired to rotate the pick-up roller  26 , the holding is released, thereby engaging the sheet feeding cassette sheet supplying non-toothed gear  822  by the idle gear  821 .  
         [0053]    On the other hand, as shown in FIG. 6, when the stepping motor  811  is rotated in a direction shown by the arrow in FIG. 6, the driving shaft  815  is rotated reversely. In this case, since the rotation is not transmitted to the driving gear  816  by the action of the one-way clutch  817 , the driving gear  816  is stopped. Thus, when the stepping motor  811  is rotated in the direction shown by the arrow in FIG. 6, the pick-up roller  26  is not rotated. However, the driving rotary lever  851  receives the rotational force of the driving shaft  815  through the one-way bearing  818  and is rotated in a direction shown by the arrow in FIG. 6.  
         [0054]    When the driving rotary lever  851  is rotated in the direction shown by the arrow in FIG. 6, the multi sheet supplying driving arm  852  is rotated in a direction shown by the arrow in FIG. 6 in opposition to the multi sheet supplying driving arm spring  853 , with the result that the regulation of rotation of the multi sheet supplying non-toothed gear  844  caused by the multi sheet supplying driving arm  852  is released. As a result, the multi sheet supplying non-toothed gear  844  is rotated by the multi sheet supplying non-toothed gear spring  845 , with the result that a non-toothed portion (not shown) is not opposed to and is engaged by the idle gear  843 . Consequently, a driving rotation transmitting path is connected between the multi sheet supplying non-toothed gear  844  and the stepping motor  811 .  
         [0055]    Again, when the stepping motor  811  is rotated in the direction shown by the arrow in FIG. 5, the rotational force of the stepping motor  811  is transmitted to the multi sheet supplying non-toothed gear  844  through the starting gear  812 , idle gears  813 ,  814 , driving shaft  815 , one-way bearing  817 , driving gear  816  and idle gears  831 ,  841 ,  842 ,  843 , with the result that the pick-up roller  27  is rotated in a direction shown by the arrow in FIG. 5 together with the multi sheet supplying non-toothed gear  844 , thereby supplying the sheet S on the multi tray  25 .  
         [0056]    Incidentally, the gear train  854  comprised of the idle gears  841 ,  842 ,  843  and the multi sheet supplying non-toothed gear  844  is provided on the sheet feeding cassette  22 , so that, when the sheet feeding cassette  22  is mounted to the main body  10  of the apparatus, the idle gear  841  is engaged by the idle gear  831  of the main body  10  of the apparatus, thereby permitting the transmission of the driving force.  
         [0057]    Further, when the stepping motor  811  is rotated in the direction shown by the arrow in FIG. 5, the registration roller  834  is also rotated. However, since the non-toothed portion  822   a  of the sheet feeding cassette sheet supplying non-toothed gear (first non-toothed gear)  822  is opposed to the idle gear  821  and is engaged by a lever (not shown) and is held by a solenoid (engaging/disengaging means), the pick-up roller  26  of the sheet feeding cassette supplying means  20  is not rotated. That is to say, the sheet feeding cassette sheet supplying non-toothed gear  822  and the solenoid (not shown) constitute simultaneous rotation preventing means for preventing of simultaneous rotations of the pick-up roller  26  of the sheet feeding cassette supplying means  20  and of the pick-up roller  27  of the multi supplying means  21  which will be described later.  
         [0058]    On the other hand, again, when the stepping motor  811  is rotated in the direction shown by the arrow in FIG. 5, as shown in FIG. 8, the driving shaft  815  is rotated in an anti-clockwise direction, and the driving rotary lever  851  is also rotatingly driven through the one-way bearing (by more or less friction in the one-way bearing  818 ). As a result, the multi sheet supplying driving arm  852  is biased by the multi sheet supplying driving arm spring  853  to be returned from a broken line position to a solid line position in FIG. 8. However, the driving rotary lever  851  abuts against a fixed stopper pin  17  and is stopped. The driving shaft  815  is rotated in an anti-clockwise direction by the action of the one-way bearing  818 . The multi sheet supplying driving arm  852  is rotated from the broken line position to the solid line position, thereby permitting the regulation of rotation of the multi sheet supplying non-toothed gear  844 . As a result, when the multi sheet supplying non-toothed gear  844  is rotated by about one revolution together with the pickup roller  27 , the engaging portion  852   a  of the multi sheet supplying driving arm  852  is engaged by the engaged portion  844   a  of the multi sheet supplying non-toothed gear  844 , thereby stopping the rotation of the pick-up roller  27 . In this case, the non-toothed portion (not shown) of the multi sheet supplying non-toothed gear  844  is opposed to the idle gear  843 , thereby interrupting the transmission of the rotational force of the stepping motor  811 . Further, in this case, the multi sheet supplying non-toothed gear spring  845  is in a pulled condition. Thus, the initial condition is restored for preparing a next sheet feeding operation.  
         [0059]    [0059]FIGS. 9 and 10 is graph and table for showing a multi sheet supplying operation sequence for effecting the multi sheet supplying by temporarily rotating the stepping motor  811  reversely. In FIGS. 9 and 10, when the stepping motor  811  is changed from normal rotation ( 1 ) in the direction shown by the arrow in FIG. 5 to the stopping ( 2 ) and then to reverse rotation ( 3 ) in the direction shown by the arrow in FIG. 6, the driving rotary lever  851  starts to be rotated toward a pushing position of the multi sheet supplying driving arm  852  shown by the phantom line in FIG. 8 ( 4 ). When the stepping motor  811  is changed from the reverse rotation ( 3 ) to the stopping ( 7 ), the driving rotary lever  851  reaches the pushing position of the multi sheet supplying driving arm  852  shown by the phantom line in FIG. 8 ( 7 ). Thereafter, when the stepping motor  811  effects the normal rotation ( 8 ) ( 9 ), the driving rotary lever  851  starts to be rotated toward the initial position shown by the solid line ( 9 ) ( 10 ). As a result, the pick-up roller  27  starts to be rotated ( 9 ). During the normal rotation ( 12 ) of the stepping motor  811 , the driving rotary lever  851  is stopped at the initial position shown by the solid line ( 11 ) ( 12 ). Thereafter, the rotation of the pick-up roller  27  is stopped ( 12 ).  
         [0060]    In this way, since the sheet supplying means according to the illustrated embodiment does not utilize the solenoid for operating the multi sheet supplying starting arm  852  when the sheet S is supplied from the multi tray  25  to the image forming means  12 , the solenoid, and a substrate, a cable and a connector required for the solenoid can be omitted, thereby simplifying the structure and reducing the cost.  
         [0061]    Next, a construction in which the sheet supplying means  8  is designed as a unit will be explained with reference to FIGS.  11  to  13 . The sheet supplying means  8  is constituted as a unit together with a mechanism (such as a sheet supplying driving gear train  82  for starting the supplying of the sheet from the multi tray  25  effected by the reverse rotation of the stepping motor  811 , and the driving rotary lever  851 ), and mechanical and electrical parts required for the sheet feeding operation.  
         [0062]    In FIG. 12, a common sheet supplying sensor substrate (substrate)  86  is provided with a sheet feeding cassette supplying sheet presence/absence detecting sensor (first sheet detecting means)  861  for detecting whether the sheet S exists in the sheet feeding cassette supplying means  20  or not, a multi supplying sheet presence/absence detecting sensor (second sheet detecting means)  862  for detecting whether the sheet S exists on the multi tray  25  or not, and a sheet leading end detecting sensor  863  for detecting a leading end of the sheet S in the vicinity of the registration roller  834 . Incidentally, photo-sensors of permeable type are used as these sensors.  
         [0063]    The sheet supplying means  8  is reinforced by a sheet supplying casing  80 . In FIG. 13, the sheet supplying sensor substrate  86  is attached to a right end of the sheet supplying casing  80 . In FIG. 11, the detecting sensors  861 ,  862 ,  863  are protruded into the sheet supplying casing  80 . A sheet feeding cassette supplying sheet presence/absence detecting sensor lever  871  is rotatably disposed in the vicinity of the sheet feeding cassette supplying sheet presence/absence detecting sensor  861  to perform its detecting function, a multi supplying sheet presence/absence detecting sensor lever  872  is rotatably disposed in the vicinity of the multi supplying sheet presence/absence detecting sensor  862  to perform its detecting function, and a sheet leading end detecting sensor lever  873  is rotatably disposed in the vicinity of the sheet leading end detecting sensor  863  to perform its detecting function. By arranging the detecting sensors  861 ,  862 ,  863  on the single sheet supplying sensor substrate  86  collectively in this way, relay cables for connecting between the detecting sensors  861 ,  862 ,  863  and the sheet supplying sensor substrate  86  can be omitted, thereby enhancing the reliability and reducing the cost.  
         [0064]    Further, the pick-up roller  26 , the registration roller  834  and a U-turn roller  835  which serve to separate and convey the sheets S on the cassette tray  23  and the multi tray  25 , the sheet supplying driving gear train  82  for transmitting the driving force to these rollers, and the stepping motor  811  are attached to the sheet supplying means  8 . Thus, the sheet supplying means  80  according to the illustrated embodiment is characterized in that it integrally includes a sheet supplying starting mechanism for starting the supplying of the sheet from the multi tray  25  effected by the reverse rotation of the stepping motor  811 , and mechanical and electrical parts required for the supplying. With this arrangement, the detachable mounting to the main body  10  of the color printer can be facilitated, and assembling ability and maintenance of the color printer  9  can be enhanced.  
         [0065]    By the way, as mentioned above, by driving the pick-up roller  27  and the conveying roller pair  29  of the multi supplying means  21  by means of the driving portion provided in the main body  10  of the apparatus and by eliminating electrical connection between the main body  10  and the sheet feeding cassette  22  by effecting the electrical connection of the solenoid used for the rotation control within the main body of the apparatus, even when the multi supplying means is provided, the construction of the sheet feeding cassette  22  can be simplified, and the number of parts can be reduced.  
         [0066]    Further, when the driving means is not provided in the multi supplying means  21 , as mentioned above, the multi supplying means  21  and the sheet feeding cassette  22  having such multi supplying means can be made compact, thereby making the entire printer compact.  
         [0067]    On the other hand, in the illustrated embodiment, as shown in FIG. 14, a frame  22 A of the sheet feeding cassette  22  has a mono-cock structure molded from single molding material so that the sheet feeding cassette  22  and the multi supplying means  21  are formed integrally. By integrally forming the sheet feeding cassette  22  and the multi supplying means  21  in this way, the number of parts can be reduced, and the cost can be reduced.  
         [0068]    Incidentally, the construction of the sheet feeding cassette  22  is not limited to that shown in FIG. 14, but, for example, as shown in FIG. 15, a frame may be divided into a frame  22 B for the sheet feeding cassette  22 , and a frame  22 C on which the multi supplying means is mounted, and these frames  22 B,  22 C may integrally secured to each other by fastening means such as screws.  
         [0069]    By dividing the frame into the frames  22 B,  22 C in this way, i.e., by detachably attaching the multi supplying means  21  to the sheet feeding cassette  22 , the sheet feeding cassette  22  can also be used as a sheet feeding cassette only requiring optional sheet feeding cassette sheet containing portion (cassette tray  23 ), the number of parts can be reduced, and the space assumed by the unnecessary functions can be reduced.  
         [0070]    Further, as shown in FIG. 16, the sheet feeding cassette  22  may be designed so that the multi tray  25  of the multi supplying means  21  is rotatably (shiftably) provided in the main body  10  of the apparatus and, only when the multi supplying means is used, the multi tray  25  is rotated downwardly.  
         [0071]    With this arrangement, when the multi supplying means  21  is not used, the multi tray  25  can be contained within the main body of the apparatus, thereby saving the space. Further, when the multi-tray  25  is not provided on the sheet feeding cassette  22 , the latter can be lightened.