Abstract:
A sheet supplying device supplies a sheet to a sheet supplied apparatus which has a predetermined maximum size of the sheet capable of being supplied thereto. The sheet supplying device includes a movable cassette for placing the sheet thereon and movable to at least two transport positions so as to transport the sheet therefrom to the sheet supplied apparatus in at least two transparent directions, and a driving device, to which a driving order is given, for moving the movable cassette to at least two transport positions in response to the driving order. The sheet supplying device further includes a control device, to which the size of the sheet placed on the movable cassette is input, for stopping the driving motion of the driving device prior to the driving order if the input size of the sheet exceeds the maximum size when the movable cassette is moved.

Description:
RELATED APPLICATIONS 
     This application is related to commonly assigned copending applications: Ser. No. 07/515,740 filed Apr. 30, 1990, Ser. No. 07/523,800 filed May 15, 1990, Ser. No. 07/521,692 filed May 10, 1990 (now U.S. Pat. No. 4,998,137) and Ser. No. 07/521,693 filed May 10, 1990. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a sheet supplying device for use in a copier, a printer and the like. 
     2. Description of the Related Art 
     An apparatus supplied with a sheet material, for example, a copier which is supplied with copying sheets, such as paper, is provided with a sheet supplying device. The sheet supplying device is provided with a plurality of sheet supplying cassettes with each cassette corresponding to a plurality of sizes of the sheet. A lateral transport for transporting a sheet in the direction of its width is more preferable in view of the transport speed than a longitudinal transport for transporting a sheet in its longitudinal direction. There exists a copier which enables the lateral transport of even large-sized sheets such as B4- and A3-sized sheets. 
     On the contrary, in order to transport such a large-sized sheet in the lateral direction, it is required that the photoconductive drum, the transport roller, the transport path, etc. in the copier are also large, resulting in the increase of size and cost of the copier. Therefore, a method is preferably used for transporting a large-sized sheet, such as B4-, A3-sized sheets, in the longitudinal direction, while transporting a small-sized sheets, such as sheets of not larger than A4-size, in the lateral direction. 
     However, in the case, for example, where the copier has a variable magnification function for reducing or enlarging an image, the copier needs B5R- and A4R-sheet cassettes for a longitudinal transport in a reduction copying operation, and further needs B5 and A4-sheet cassettes for a lateral transport in a normal copying operation in consideration of the transport speed. If such various types of cassettes are used in the copier, it is required that the sheet supplying device shall be large to accommodate all of those cassettes, or that one of those cassettes shall be selected and exchanged at the sheet supplying device according to the purpose of each copying operation. As a result, this makes the copier large and thus increases the cost, or complicates the copying operation and thus increases the operation time. 
     Thus, in order to solve the above problem, a conventional sheet supplying device has been proposed, wherein a common cassette is used for supplying a same sized sheet in two different transport orientations, for example, a common cassette for B5 and B5R and a common cassette for A4 and A4R are used, and the switching between the lateral transport and the longitudinal transport is done by turning the cassette, as disclosed in the Japanese Patent Application Laying Open (KOKAI) No. 56-59245, No. 59-123859, etc. 
     However, in the above conventional supplying device, the following problem arises: that is, since in a conventional copier, the maximum size of a sheet capable of being supplied is limited by mechanical conditions, such as the length of a photoconductive drum in the copier&#39;s main body, the length of a developing magnet roller, the width of the sheet transport path and so on, the sheet sometimes cannot be fed to the main body of the copier, depending upon the size of the sheet, for example, when the transport orientation of the sheet is changed from the orientation for longitudinal transport to the orientation for lateral transport by turning a turning cassette in the above conventional apparatus. In this case, the turning of the turning cassette results in a useless motion with wasting time and energy, and maybe causing a mechanical trouble. Therefore, it has been desired to develop a device to alleviate the above disadvantage. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a sheet supplying device having a driving mechanism in order to supply a sheet in various transport orientations, in which a useless motion can be prevented. 
     According to the present invention, the above object can be achieved by a sheet supplying device for supplying a sheet to a sheet supplied apparatus which has a predetermined maximum size of the sheet capable of being supplied thereto. The sheet supplying device includes a movable sheet placing means having a plane for placing the sheet thereon and movable to at least two transport positions so as to transport the sheet therefrom to the sheet supplied apparatus in at least two transport orientations, and a driving means, to which a driving order is given, for moving the movable sheet placing means to said at least two transport positions in response to the driving order. The sheet supplying device further includes a control means, to which the size of the sheet placed on the movable sheet placing means is input, for preventing the driving motion of the driving means prior to the driving order if the input size of the sheet exceeds the maximum size when the movable sheet placing means is moved. 
     According to the above sheet supplying device, when the driving order is given to the driving means by the operator in order to change the transport position of the movable sheet placing means, the control means prevents the motion of the driving means prior to this driving order if the size of the sheet placed on the movable sheet placing means exceeds the predetermined maximum size capable of being supplied to the sheet supplied apparatus. Accordingly, even if an improper driving order is given to the driving means by a mistake of the operator and so on, a useless movement of the movable sheet placing means can be prevented, thus, the wastes of the operation time and the driving energy is effectively avoided. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a general view showing the overall configuration of a copier provided with a sheet feeding device according to an embodiment of the present invention; 
     FIG. 2 is a perspective view showing that a second turning cassette unit of the copier as shown in FIG. 1 is drawn out; 
     FIG. 3 is a perspective fragmentary sectional view of a first and a second turning cassette units as shown in FIG. 1; 
     FIG. 4 is an enlarged perspective view of a nut member portion as shown in FIG. 3; 
     FIG. 5 is a perspective view of a cassette mounting section provided with switches and a pressing projection portion of each fixed cassette of the copier shown in FIG. 1. 
     FIG. 6 is a front view of an operation panel of the copier as shown in FIG. 1; 
     FIG. 7 is a front view of a cassette operation section of the operation panel as shown in FIG. 6; 
     FIG. 8 is a block diagram of a control device of the sheet feeding device as shown in FIG. 1; 
     FIG. 9 is an explanation view of turning process of the turning cassette as shown in FIG. 1; and 
     FIG. 10 is a flow chart showing a control operation of the sheet feeding device as shown in FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the accompanying drawings, an embodiment of the present invention will be now explained. 
     As shown in FIG. 1, a copier comprises a desk section 38 under a main body 1, which is a sheet material supplied apparatus, a sorter 19 on the paper eject side of the main body 1, and an automatic document feeding device (referred to as ADF hereinafter) 3 on the main body 1. 
     The main body 1 includes a first fixed cassette 29, and a second fixed cassette 28. 
     The desk section 38, as shown in FIG. 2, includes a both sides composition unit 21, a first turning cassette unit 26, a second turning cassette unit 27, and a third fixed cassette 25 in a positional order starting from the top of the desk section 38. 
     Each of the first and second turning cassette units 26, 27 has a movable turning cassette 32 as an example of a movable sheet placing means in each outer housing 31. 
     The first, second and third fixed cassettes 29, 28, 25 are examples of a fixed sheet placing means. The movable cassettes 32 and the fixed cassettes 25, 28, 29 are thus provided to a sheet feeding device 39 as an example of a sheet supplying device. 
     The ADF 3 is located on a document table glass 2 of the main body 1. The ADF 3 transports a document, not shown, laid on a document table 3a to a predetermined position on the document table glass 2 in response to its size and orientation longitudinal or lateral transport, and ejects the document after the document is copied. Furthermore, the ADF 3 transports the document to the predetermined position on the document table glass 2 again after turning the document upside down in case that both sides copying of the document is to be performed. After the other side is copied, the document is then ejected. 
     Mounted on the document table 3a, are transport direction switches 5a, 5b for detecting the size of the document in the transport direction and a guide 4 for limiting both edges of the document in the direction of the width of the document. The guide 4 is provided with a width direction switch, not shown, for detecting the size of the document in the direction of its width. 
     Located below the document table glass 2 is an optical system 6, composed of a plurality of reflective mirrors 6a and lenses 6b. The fundamental function of the optical system 6 is to direct a reflective light from the document to a photoconductive drum 7. Besides that, the optical system 6 has a variable magnification function, that is, it has a composition which enables enlargement and reduction copying as well as equivalent magnification copying to be performed. 
     Around the photoconductive drum 7, are arranged a cleaner 8, a discharger 9, a charger 10, a developing device 11 containing a toner for color development, and a developing device 12 containing a black toner. These means and the above optical system 6 execute a series of processes, that is, charging, exposing, developing, removing of residual toner and discharging, for the photoconductive drum 7. 
     Below the photoconductive drum 7, there is arranged a transfer charger 13, by which a toner image on the photoconductive drum 7 is transferred onto the sheet supplied to the photoconductive drum 7, and a separation charger 14, by which the above sheet is separated from the photoconductive drum 7. Then, the sheet is transported by means of a transport belt 17 to a fixing device 18. The fixing device 18 fixes the toner image on the sheet by heat or pressure. 
     Though the sheet transported in the fixing device 18 is normally ejected onto eject trays 19a, through a sorter 19, if both sides copying or composition copying is to be performed, the sheet is led through a sheet return path 20 to the composition unit 21. In the both sides copying operation, the sheet is turned upside down onto an intermediate tray 21c after passing through a first transport path 21a in the composition unit 21, and then the sheet is fed to a sheet feed transport path 22 by a feeding roller 21d. In the composition copying operation, after the sheet is transported to a second transport path 21b in the composition unit 21 and its rear edge is detected in the second transport path 21b, the sheet is fed forward by a switchback with the previous rear edge now being the front edge. The sheet is turned upside down onto the intermediate tray 21c after passing through the first transport path 21a, and then, fed to the sheet feed transport path 22 by the feeding roller 21d. 
     The sheet feed transport path 22 extends to the vicinity of the photoconductive drum 7 and is provided with a paper stop roller 15 at the rear end portion thereof for timing the rotation of the photoconductive drum 7 and the feeding of the sheet. To the sheet feed transport path 22 are connected a plurality of sheet feeding means, from which the sheet is properly supplied. Concretely, this plurality of sheet feeding means include a manual sheet feeding section 30, a first fixed cassette 29 capable of containing at most 500 sheets, a second fixed cassette 28 capable of containing at most 250 sheets, the composition unit 21, the first turning cassette unit 26, the second turning cassette unit 27, and the third fixed cassette 25 containing at most 250 sheets. The length of the sheet transport path from each of the respective sheet feeding means to the paper stop roller 15 increases the closer the respective sheet feeding means is located to the bottom of the desk section 38. The first fixed cassette 29 and the second fixed cassette 28 arranged in the main body 1 and the composition unit 21, the first turning cassette unit 26, the second turning cassette unit 27 and the third fixed cassette 25 arranged in the desk section 38, constitute a group of cassettes in the sheet feeding device 39. Each of the above fixed cassettes 29, 28, 25 and the turning cassettes unit 26, 27 is detachably mounted and provided with a transporting device 29a, 28a, 25a, 26a, 27a respectively for taking and transporting the sheet from each cassette to the transport path 22. 
     As shown in FIG. 3, each of the first and second turning cassette units 26, 27 includes the outer housing 31 and a turning cassette 32 containing sheets of a predetermined size. The turning cassette 32 is provided with a turning plate, not shown, for lifting the sheets in the turning cassette 32 in response to the reduction of the sheets. On the bottom plate of the outer housing 31, is mounted a cassette supporting plate 33 whose center portion is apart from the bottom plate of the outer housing 31. A guide aperture 33a, which is elongated in the direction for feeding the sheet, is formed on the center portion of the cassette supporting plate 33. From the center portion of the lower side of the turning cassette 32, a guide axis 34 projects downward so as to engage the guide aperture 33a. The guide axis 34 is adapted to slide in the guide aperture 33a. 
     Furthermore, the outer housing 31 is provided with a threaded shaft 35 in parallel relationship with a feeding plane vertical to the direction for feeding the sheet from the turning cassette 32 and the bottom plate of the outer housing 32. The threaded shaft 35 is supported by a bearing, not shown, and rotatable in two directions by connecting one of its edges to a cassette turning motor 36. A nut member 37 is engaged with the threaded shaft 35 so that the nut member 37 can reciprocate in the axial direction associated with the rotation of the threaded shaft 35 in two directions. As shown in FIG. 4, a top portion of the nut member 37 is rotatably connected to one of a corner portion of the turning cassette 32. At a bottom portion of the nut member 37, a shading plate 37a is formed. 
     On the bottom plate of the outer housing 31 below the vicinity of each end of the threaded shaft 35, there is mounted a lateral transport position sensor HP1, which detects the state where the turning cassette 32 is turned and moved to a predetermined lateral transport position, and a longitudinal transport position sensor HP2, which detects the state where the turning cassette 32 is turned moved to a longitudinal transport position, respectively. Each of the two sensors is composed of a light emitting element and a light receiving element. When the turning cassette 32 is moved to the predetermined lateral and longitudinal transport positions, the shading plate 37a interrupts the light being emitted from the light emitting element to the light receiving element, and thereby the position sensors HP1, HP2 detect the movement of the turning cassette 32 to the predetermined position. The position sensors HP1, HP2 may be not only photointerrupters but also magnetic sensors, contact type switches and so on. 
     As shown in FIG. 5, each of the fixed cassettes 29, 28, 25 mounted on the copier&#39;s main body 1 and the desk section 38 is provided with a pressing projected portion 61. The pressing projected portion 61 is positioned in a predetermined position so as to correspond to the size and transport orientation of the sheets stacked in each of the fixed cassettes 29, 28, 25. On the other hand, a plurality of sheet size switches 63, which are pressed and turned ON by the pressing projected portion 61, are mounted at the cassette mounting section 62 of each of the copier&#39;s main body 1, mounting the fixed cassettes 29, 28, and the desk section 38 mounting the fixed cassette 25. The sheet size switches 63 are connected to the microcomputer 51 described below. Such a composition of the embodiment enables the microcomputer 51 to know the size and transport orientation of the sheets stacked in each of the cassettes 29, 28, 25 when each of the cassettes 29, 28, 25 is mounted to the copier&#39;s main body 1 or the desk section 38. On the other hand, only the size of the sheets stacked in the turning cassette 32 is input to the microcomputer 51 by the same detection means as described above or other detection means. Orientation information is detected by sensors HP1 and HP2 as described later in connection with FIGS. 8 and 9. 
     The main body 1 of the copier is provided with an operation panel 40 on its upper surface, as shown in FIG. 6. 
     The operation panel 40 comprises a copy button 41 for directing the start of a copying operation, ten keys 42 for setting the number of copies and so on, a copy number display 43, a cassette operation section 44, a magnification display 45, magnification setting keys 46, etc. 
     The cassette operation section 44 comprises, as shown in FIG. 7, a cassette switch key 47 for selecting a cassette, a cassette turning key 48 for directing the turning of the turning cassette 32 in the first turning cassette unit 26, and a cassette turning key 49 for directing the turning of the turning cassette 32 in the second turning cassette unit 27. Furthermore, the cassette operation section 44 comprises sheet size display lamps PSL1 to PSL6 and cassette display lamps CSL1 to CSL6 displaying the manual sheet feeding section 30, the first fixed cassette 29, the second fixed cassette 28, the first turning cassette unit 26, the second turning cassette unit 27, and the third fixed cassette 25 as respectively numerals 1 to 6 in the above order. These cassette display lamps CSL1 to CSL6 are turned ON when the cassette switch key 47 is operated and either one of the turning cassette units 26, 27, any of the fixed cassettes 25, 28, 29, or the manual sheet feeding section 30 is selected. For example, if the first turning cassette unit 26 is selected in response to the operation of the cassette switch key 47, the cassette display lamp CSL4 is turned ON and further, if the A4-sized sheets are stacked in the turning cassette 32 of the first turning cassette unit 26, the sheet size display lamp PSL3 is turned ON to display that the sheet is A4-sized. In this case, when the cassette turning key 48 is operated, the turning cassette 32 is turned from the lateral transport position to the longitudinal transport position and the sheet size display lamp PSL4 is turned ON to display that the sheet is A4R-sized. If no sheet is stacked in the turning cassette units 26, 27, the fixed cassettes 25, 28, 29, or the manual sheet feeding section 30, the sheet size display lamps PSL1 to PSL6 are not turned ON. 
     As shown in FIG. 8 the sheet feeding device 39 includes a microcomputer 51 as a control means. To the above microcomputer 51, are connected a motor driver circuit 52, the position sensors HP1, HP2, sheet size switches 63, a document size detection device 54, operation panel keys 55, operation panel display devices 56, a turning cassette unit feeding solenoid 57, a sheet insert detection switch 58, etc. Accordingly, the sheet feeding device 39 is equipped with the fixed cassettes 29, 28, 25, the composition unit 21, the turning cassette units 26, 27, the transport device 29a, 28a, 25a, 26a, 27a, the microcomputer 51, the motor driver circuit 52, and the cassette turning motor 36. 
     The motor driver circuit 52 and the cassette turning motor 36 constitutes a cassette turning driving means and, though not shown in FIG. 8, they are provided in the first and second turning cassette units 26, 27 respectively. The motor driver circuit 52 is composed of pull-up resistors R1, R2, NOT circuits 59, 60, transistors Tr1 to Tr4, resistors R3 to R8, and diodes D1 to D4 as surge absorbers, and drives the cassette turning motor 36 in two directions of rotation in response to the output of the microcomputer 51. The pull-up resistor R1, an input port of the NOT circuit 59 and a base of the transistor Tr4 are connected to an output terminal CW and an output port of the NOT circuit 59 is connected to a base of the transistor Tr1 through the resistor R3. To the base of the transistor Tr1, and end of the resistor R4 is connected, and to a base of the transistor Tr2, and end of the resistor R5 is connected. The other ends of these resistors R4 and R5, emitters of the transistors Tr1 and Tr2 and cathodes of the diodes D1 and D2 are connected to one another. The points where they are connected have a voltage of +24 V applied to them. Furthermore, a collector of the transistor Tr1 and an anode of the diode D1 are connected to one of the input terminals of the cassette turning motor 36. A collector of the transistor Tr2 and an anode of the diode D2 are connected to the other input terminal of the cassette turning motor 36. On the other hand, the pull-up resistor R2, an input port of the NOT circuit 60 and a base of the transistor Tr3 are connected to an output terminal CCW of the microcomputer 51. An output port of the NOT circuit 60 is connected to a base of the transistor Tr2 through the resistor R6. To the base of the transistor Tr3, an end of the resistor R7 is connected. To a base of the transistor Tr4, an end of the resistor R8 is connected. The other ends of these resistors R7 and R8, emitters of the transistors Tr3 and Tr4 and anodes of the diodes D3 and D4 are connected to one another. The points where they are connected have a voltage of +24 V applied to them. Furthermore, a collector of the transistor Tr3 and a cathode of the diode D3 are connected to one of the input terminals of the cassette turning motor 36. A collector of the transistor Tr4 and a cathode of the diode D4 are connected to the other input terminal of the cassette turning motor 36. 
     In the above motor driver circuit 52, the turning cassette 32 of the first turning cassette unit 26 or the second turning cassette unit 27 is turned to the lateral transport position, for example, an A4 position or a B5 position, when the output terminal CCW of the microcomputer 51 is at a high level (the output terminal CW remains LOW), and to the longitudinal transport position, for example, an A4R position or a B5R position, when the output terminal CW is at a high level. 
     The document size detection device 54 is composed of a width direction switch, not shown, mounted on the guide 4 for the document table 3a and the transport direction switches 5a, 5b and located so as to supply input terminals OS1 to OS4 of the microcomputer 51 with 4-bit data. 
     The operation panel keys 55 are the copy button 41, the ten keys 42, the magnification setting key 46, the cassette switch key 47, the cassette turning keys 48, 49 and so on. 
     The operation panel display device 56 is composed of the copy number display 43, the magnification display 45, the sheet size display lamps PSL1 to PSL6, cassette display lamps CSL1 to CSL6, etc. provided on the operation panel 40. 
     The turning cassette sheet feeding solenoid 57 is mounted so as to drive each of a taking roller 26b in the transport device 26a of the first turning cassette unit 26 and a taking roller 27b in the transport device 27a of the second turning cassette unit 27 to feed the sheet through the transport path 22. 
     The insert detection switch 58 is located immediately in front of the paper stop roller 15 shown in FIG. 1 so as to detect the arrival of the sheet at the paper stop roller 15. 
     When any key of the operation panel keys 55 is operated, the microcomputer 51 performs the control in response to the operation. For example, when the cassette turning key 48 corresponding to the first turning cassette unit 26 is operated so as to direct the turn of the turning cassette 32 in the first turning cassette unit 26 from the lateral transport position to the longitudinal transport position, the output terminal CW is turned to a high level and the output terminal CCW is turned to a low level, while, if the key operation directs the turn from the longitudinal transport position to the lateral transport position, the output terminal CCW is turned to a high level and the output terminal CW is turned to a low level. When the turning cassette 32 is moved to the lateral transport position and the cassette position sensor HP1 is turned ON, that is, the light in the photointerrupter is interrupted, the output terminal CCW is turned to a low level at once and the cassette turning motor 36 is stopped. In the same way, when the turning cassette 32 is moved to the longitudinal transport position and the cassette position sensor HP2 is turned ON, the output terminal CW is turned to a low level and the cassette turning motor 36 is stopped. 
     The microcomputer 51 also has an automatic sheet selection function for determining the size of the document based on the 4-bit data input from the document size detection device 54, and automatically selecting the cassette which contains the sheets corresponding to the document size. In addition, as described later with reference to FIG. 10, the microcomputer 51 controls the movable cassette of the first or second turning cassette unit 26, 27 by changing an output level of the output terminals CW and CCW. 
     In the above construction, the turning motion of the turning cassette 32 will be first explained by way of an example of the first turning cassette unit 26 with reference to FIG. 9. 
     Assuming that the A4-sized sheets are stacked in the turning cassette 32 of the first turning cassette unit 26 and the turning cassette 32 is at the lateral transport position (A4 position), the position sensor HP1 is turned ON and A4 is displayed on the portion corresponding to the first turning cassette unit 26 on the operation panel display device 56. In this case, the nut member 37 arranged on the threaded shaft 35 is assumed to be positioned at Pl, as shown in FIG. 9. 
     Then, when the cassette turning key 48, corresponding to the first turning cassette unit 26, is operated from among the operation panel keys 55, the output terminal CW of the microcomputer 51 is turned high and the output terminal CCW is turned low. Thereby, the transistors Tr1, Tr4 are turned ON, the electric current runs by way of the +24 V power source, the transistor Tr1, the cassette turning motor 36, the transistor Tr4 and to ground in this order, and the cassette turning motor 36 rotates in a normal direction (the direction of C as shown in FIG. 3). As a result, the threaded shaft 35 also rotates in the C direction. The rotation moves the nut member 37 from P1 to P6. The guide axis 34 of the turning cassette 32 slides in the guide aperture 33a of the cassette supporting plate 33 with its rotation and reciprocates in the order of Q1 to Q6. When the nut member 37 arrives at the position sensor HP2 and the position sensor HP2 is turned ON, the cassette turning motor 36 is stopped. Then, the turning cassette 32 is positioned in a predetermined longitudinal transport position (A4R position). 
     When the cassette turning key 48 is operated again in this state, the output terminal CCW of the microcomputer 51 is turned high, the output terminal CW is turned low, and the transistors Tr2, Tr3 are turned ON. The electric current runs by way of the +24 V power source, the transistor Tr2, the cassette turning motor 36, the transistor Tr3 and to ground in this order and the cassette turning motor 36 reversely rotates. Therefore, the turning cassette 32 moves from the above longitudinal transport position to the lateral transport position through the process opposite to the above-mentioned case. Then, when the position sensor HP1 is turned ON, the cassette turning motor 36 stops and the turning cassette 32 is positioned at a predetermined lateral transport position. 
     Next, referring to the flow chart shown in FIG. 10, the control operation of the microcomputer 51 for the turning cassette 32 will be explained. In the embodiment, the maximum size capable to be transported to the copier&#39;s main body 1 is the B5-size in the lateral transport, that is, the B4-size in the longitudinal transport. Therefore, only when the turning cassette 32 is at the B5 position or B5R position with B5-sized sheets therein and at the A5 position or A5R position with A5-sized sheets therein, the turning cassette 32 should be allowed to turn by the control of the microcomputer 51. When the turning cassette 32 contains A4- or A3-sized sheets, it should not be allowed to turn. 
     Assuming that the cassette turning key 48 corresponding to the turning cassette 32 of the first turning cassette unit 26 is operated and the order for turning this turning cassette 32 is given, the microcomputer 51 detects the size and transport direction of the sheet stacked in the turning cassette 32 of the first cassette unit 26 (S1). The detection of the transport direction of the sheet, that is, the detection of the longitudinal or lateral transport position of the turning cassette 32 is performed based on the input from the position sensors HP1 and HP2. If the size of the sheets stacked in the turning cassette 32 are either B5, B5R, A5 or A5R (S2), the turning permission flip-flop is set (S3). If the size of the sheets stacked in the turning cassette 32 are not either B5, B5R, A5 or A5R in S2, the turning permission flip-flop is reset (S4). After that, it is judged whether or not the turning permission flip-flop is set (S5). If it is, the turning cassette 32 is turned to the predetermined position (S6). If the turning permission flip-flop is reset in S5, the turning cassette 32 is not turned and the operation is stopped. 
     As described above, according to the embodiment, even if the turning order for the turning cassette 32 is given, the turning cassette 32 is not turned when the size of the sheets stacked in the turning cassette 32 exceeds the maximum size capable of being transported after the transport direction of the sheets is changed by turning the turning cassette 32. Therefore, useless turns of the turning cassette 32 are avoided. 
     In the above described embodiment, the turning cassettes 32 are utilized for placing the sheets, but instead, a movable plate or a movable bin, which has a plane for placing a sheet and moves to different transport positions, may be utilized. Further, instead of the turning motor 36, a solenoid, an air piston or any other driving device may be utilized. 
     In the above described embodiment, the sheet may be a sheet of paper, a sheet of film, or any other sheet of copying material. 
     Many widely different embodiments of the present invention may be constructed without departing from the spirit and scope of the present invention. It should be understood that the present invention is not limited to the specific embodiments described in this specification, except as defined in the appended claims.