Image forming apparatus and roll paper cutting device therefor

Abstract: An image forming apparatus has a main body (10) to which is attached a device (12) for cutting paper from a roll and discharging the cut paper through an outlet. The cutting device is selectively shiftable to a feed position where the outlet (110) is in register with a sheet inlet (28) on the main body or to a standby position away from the feed position. The invention also provides a roll paper cutting device for transporting and cutting roll paper having detecting means (270) disposed in the path of transport of documents for detecting a document rear end so as to cut the paper with timing based on the time when the rear end is detected. There is also provided a roll paper cutting device adapted to drive transport rollers with predetermined timing based on the time when the paper travel is detected while all the transport rollers rotate idly in a standby state for paper feeding. Finally, a roll paper cutting device is provided for feeding roll paper to the main body of an image forming apparatus by forwarding the leading end of the paper to feed means (22) disposed in said main body in the paper path to the image forming station, and thereafter transporting the paper onwards by the transport means within the main body.

Description: The present invention relates to copying machines or like image forming apparatus for forming copy images, for example, on paper precut to a specified size and a roll paper cutting device for use with the apparatus. As the means for feeding copy paper to the image forming position, image forming apparatus, such as copying machines, generally have incorporated therein a cassette for containing paper precut to a specified size and delivering the cut paper therefrom one sheet after another. Alternatively, sheets of such cut paper are manually inserted one by one into a copy paper inlet formed in the body of the apparatus. It is also known (JP 57-165858) to provide a section in the apparatus with a series of alternative cassettes for different sizes of cut paper. However, the apparatus for use with such cut paper has the drawback of necessitating a large space for holding the paper therein, especially when the paper to be used has a large size. Accordingly, it is known to provide paper in the form of a roll, set in a specific roll paper cutting device, the paper being cut to the desired size by the device and then fed to the image forming apparatus through a paper inlet. This method is cumbersome and inefficient because the roll paper must be cut by the device before an image forming operation. The drawback can be overcome by incorporating a roll paper cutting mechanism into the image forming apparatus, such that when a roll paper mode is selected as the paper feed mode for the apparatus, cut paper is fed from the cutting mechanism. One arrangement of this kind is known from EP 391632A, which however is not a prior publication. In this case, however, an image forming apparatus having a special and complex construction must be constructed at an increased cost. Furthermore, the user possessing an apparatus not incorporating the cutting mechanism must purchase the new apparatus. It is also known (JP 61-13864) to provide a demountable roll paper cutting device which can be placed on the image forming apparatus when larger sizes of paper are wanted, but the device has to be removed from the apparatus when smaller size precut paper is to be used in order to allow the paper to be fed from the cassette that is permanently located on the apparatus to hold the precut paper. Further in the case where the image forming apparatus is adapted to be equipped with the roll paper cutting device as an optional device, with signal communication effected to associate the device with the apparatus, the modification of the apparatus and wiring require much labour to impair the optionality. When the roll paper cutting device is to be used as such an optional device, the roll paper feed means within the device and the paper feed means within the apparatus must be adapted to transport paper at the same speed, whereas this encounters extreme difficulty. If there is a difference between the two feed means in transport speed, the roll paper is likely to become deflected or tensioned to produce an adverse effect on the formation of images especially when elongated documents are copied. Further when the two speeds are to be made identical, the drive source for the roll paper feed means, for example, must be finely adjusted, but the means for effecting the fine adjustment is expensive, consequently diminishing the advantage of the image forming apparatus. According to one aspect of the present invention, there is provided an image forming apparatus for forming an image on a sheet inserted via a sheet inlet on a main body of the apparatus, and a paper sheet cutting device for a paper roll adapted to cut a sheet from the roll and discharge the cut sheet via an outlet of the device, the cutting device comprising drive means for locating the cutting device selectively relative to the apparatus main body in a feed position where the outlet is in register with the sheet inlet or in a standby position where the outlet is out of register with the sheet inlet, and guide means are provided on the main body for guiding the cutting device vertically between said feed and standby positions. When the roll paper cutting device of the above apparatus is shifted to the feed position, a sheet of paper cut off from the roll paper by the device can be fed from the outlet into the apparatus body through the sheet inlet thereof. Alternatively, with the roll paper cutting device shifted from the feed position to the standby position, cut paper can be fed to the apparatus main body manually from the sheet inlet thereof. This results in the advantage that images can be formed not only on cut paper but also on roll paper utilizing an existing image forming apparatus and using an inexpensive construction. In another aspect of the invention, there is provided a sheet paper cutting device separably attachable to an apparatus for forming an image on a sheet inserted via a sheet inlet on a main body of the apparatus, the cutting device comprising means to cut a sheet from a paper roll and discharge the cut sheet via an outlet of the device to an inlet on a main body of the image forming apparatus, the paper sheet cutting device further comprising means arranged to cooperate with means on the apparatus for location of the cutting device thereon, and drive means for displacing the cutting device relative to the main body to adjust the cutting device selectively on the apparatus between a feed position where the outlet is in register with the sheet inlet or a standby position where the outlet is out of register with the sheet inlet. The above and other objects, features and advantages of the present invention will become more apparent upon a reading of the following detailed description and the drawings. Fig. 1 is a diagram showing the overall construction of a first embodiment of the invention, ie. an image forming apparatus; Fig. 2 is a diagram of the interior construction of a copying assembly in the image forming apparatus; Fig. 3 is an overall diagram showing a drive system for a roll paper cutting device in the image forming apparatus; Fig. 4 is a view in section taken along the line IV-IV in Fig. 3; Fig. 5 is a view in section taken along the line V-V in Fig. 3; Fig. 6 is a fragmentary view of the drive system as it is seen in the direction of arrow A in Fig. 3; Fig. 7 is a block diagram showing the input-output relationship of a control system included in the roll paper cutting device; Fig. 8 is a view showing the interior construction of the roll paper cutting device; Figs. 9 and 10 are flow charts showing the control operation to be performed by the control system of the cutting device; Fig. 11 is a side elevation partly broken away and showing a mount structure for a copy paper guide member in the image forming apparatus; Fig. 12 is a side elevation partly broken away and showing a mount structure for a copy paper guide member included in another image forming apparatus as a second embodiment; Fig. 13 is a perspective view partly broken away and showing the mount structure; and Fig. 14 is a block diagram showing the main components of another image forming apparatus as a third embodiment. Fig. 1 shows the overall construction of a copying machine (image forming apparatus) embodying the present invention. The copying machine comprises a main body 10 and a roll paper cutting device 12. The main body 10 comprises a copying assembly 14, and a copy paper stocking frame 16 having the copying assembly 14 supported thereon. The term "roll paper" is herein used not in a narrow sense of the term but includes, for example, roll film for use in preparing second original drawings. Fig. 2 shows the interior construction of the copying assembly 14, which has in its lower portion a large paper cassette (sheet container) 18 withdrawably. The cassette 18 contains copy paper, which is transported to a photosensitive drum 26 at a higher level via pairs of feed rollers 20,22 and a pair of register rollers 24. At the front side (right-hand side in Fig. 2) of the copying assembly 14, a copy paper inlet 28 is positioned above the cassette 18. Copy paper is also inserted into the inlet 28 and fed to the copying assembly 14 via the pair of feed rollers 22. Successively arranged around the photosensitive drum 26 in the direction of rotation thereof are a main charger 30, a developing unit 32, the pair of register rollers 24, a transfer-separation unit 34, a cleaner 36, etc. A fixing unit 38 and a pair of discharge rollers 40 are disposed downstream from the drum 26 with respect to the direction of transport of the copy paper, i.e., toward the front side. At the upper side of the copying assembly 14, a document feed path 42, an exposure unit 44 and a document reversing member 45 are arranged one after another. The exposure unit 44 includes a plurality of rollers 46 for transporting documents, an exposure lamp 48, a lens array 50, etc., whereby an image of the document to be transported is projected onto the drum 26. Further provided inside the copying assembly 14 are a paper absence switch (sheet detecting means) 52 for detecting whether copy paper is present in the cassette 18, and a cassette insertion switch 54 for detecting whether the cassette 18 has been completely loaded in place. Jam sensor switches 56 to 59 are arranged at two positions upstream from the pair of transport rollers with respect to the paper transport direction, at a position downstream from the drum 26 and at the position of the pair of discharge rollers 40, respectively. These switches 56 to 59 detects the copy paper passing the respective positions. If each of the switches 56 to 59 fails to detect the copy paper upon lapse of a predetermined period of time after the feed of the copy paper, this is interpreted as indicating occurrence of a jam. The document feed path 42, transfer-separation unit 34, fixing unit 38, discharge roller pair 40, etc. are accommodated in,a common unit housing 60 as a single unitary assembly, which can be withdrawn toward the front in the event of a jam. The copy paper stocking frame 16 is internally provided with a copy paper stocking tray (stocking portion) 61 slanting upward toward the front side as seen in FIG. 1. The inlet side portion of the tray, i.e., the front side portion thereof, is provided with a copy paper guide plate (guide member) 62 and a support plate 65 as shown also in FIG. 11. With reference to FIG. 11, the support plate 65 is secured to the inlet portion of the stocking tray 61, extends along the tray 61 and is provided at its front end with a restraining portion 651 projecting upward. With a hinge 67, the guide plate 62 is connected at its base end to the support plate 65 at an inside portion thereof close to the restraining portion 651 (at the left side portion in FIG. 11). Consequently, the paper guide plate 62 is forwardly unfoldable away from the front wall of the stocking frame 16, and is pivotally movable between a guide position (solid-line position in FIG. 11) in which the guide plate 62 is held projected forward by the bearing contact of the lower surface of the plate 62 with the restraining portion 651 and a retracted position (phantom-line position in FIG. 11) in which the plate 62 extends along the front wall. The copy paper delivered from the pair of discharge rollers 40 of the copying assembly 14 of FIG. 1 is guided onto the stocking tray 61 by the guide plate 62 when the plate is in the guide position. A copy paper holder 63 of polyester film or the like is provided above the stocking tray 61. The roll paper cutting device 12 is attached to the front side wall of the stocking frame 16 and is movable upward and downward. The mount structure and drive system for the device 12 will be described with reference to FIGS. 3 to 6. A pair of guide rails 64 open inward are secured to the opposite sides of the front wall of the copy paper stocking frame 16. The guide rails 64 extend from the lower end of the stocking frame 16 to the slower end of the unit housing 60 of the copying assembly 14. Within the range of length of the rails, the roll paper cutting device 12 is movable upward and downward (see the solid-line and phantom-line positions of the device 12 in FIG. 1). On the other hand, the cutting device 12 rotatably carries shafts 68, 69 extending through opposite inner side plates 66 (FIGS. 4 to 6) thereof. Rollers 71, 72 loosely fitted in the guide rails 64 are fixed to opposite ends of these shafts 68, 69. Inwardly of the rollers 71, 72 immediately adjacent thereto, sprockets 74, 75 are secured to the respective shafts 68, 69. At the respective sides of the cutting device, identical chains 76 are looped around the sprockets 74, 75 as seen in FIGS. 3 and 6. The upper and lower ends of these chains 76 are secured to the upper and lower ends of the respective guide rails 64. As seen in FIG. 5, a gear 78 is fixed to one end (closer to the plane of FIG. 3) of the shaft 72 and is in mesh with an idle gear 80 which is rotatably supported by the inner side plate 66. A drive motor 82 fixed by an unillustrated bracket to the outer side of the inner side plate 66 has a drive shaft 83 which fixedly carries a gear 84 meshing with the idle gear 80. Thus, the cutting device 12 is supported at a specified level by the guide rails 64 with which the rollers 71, 72 are in contact, and the chains 76 which are reeved around the sprockets 74, 75. Further the rotation of the drive motor 82 carried by the device 12 itself is transmitted via the gears 84, idle gear 80 and gear 78 to the shaft 69, which in turn rotates the sprockets fixed to the shaft 69 and in engagement with the respective chains 76, whereby the entire device 12 is driven upward or downward along the guide rails 64. The shaft 69 fixedly carries a pulse plate 86 as seen in FIG. 5. The device 12 further has means 88 for detecting the amount of rotation (amount of shift) comprising a photosensor including a light-emitting member and a photodetector which are positioned on opposite sides of a slit 87 formed in the pulse plate 86. The cutting device 12 further has incorporated therein a control system (control means) 90 comprising a microcomputer as seen in FIG. 7. The rotation amount detector 88 feeds a detection signal to the control system 90. The roll paper cutting device 12 further has at its upper portion a copy paper discharge tray 99 (see FIG. 1) which is open obliquely upward. With the device 12 in its upper limit position (solid-line position in FIG. 1), the copy paper delivered from the pair of discharge rollers 40 is accumulated on the discharge tray 99. The interior structure of the cutting device 12 will be described next with reference to FIG. 8. The roll paper cutting device 12 is internally provided with a roll shaft 93 for roll paper 92 upwardly and downwardly movably along a slot 94 formed in each side wall of the device. The device also has at its lower portion a pair of rotatable transport rollers 95, 96. The roll shaft 93 is biased downward by an unillustrated spring, whereby the roll paper 92 is pressed downward at all times in its entirety, with the periphery thereof held in contact with the transport rollers 95, 96 regardless of the diameter of the roll. The transport roller 95 is coupled by unillustrated gears to the driven side of a first clutch 98 which is shown also in FIG. 7. A cover 100 is openably attached to the front side (right side in FIG. 8) of the device. When opened (to the phantom-line position of FIG. 8), the cover 100 permits the user to manually set the roll paper 92 in position. Arranged above the roll paper 92 along a direction upward therefrom are a holding roller 102 (shown only in FIG. 1), a pair of feed rollers 103, 104, a pair of cutters 105, 106 and a pair of discharge rollers 108, 109. An outlet 110 for the roll paper 92 is provided above the discharge rollers. One of the feed rollers 103, 104, i.e., the feed roller 103 is coupled by gears 111, 112 to the driven side of a second clutch 114 which is shown also in FIG. 7. The other feed roller 104 is rotatably attached to a pivotal bracket 118 by a plate spring 116 and is usually held in pressing contact with the feed roller 103 by being biased with the plate spring 116. With the cover 100 in its opened state, the roller 104 can be moved out of contact with the roller 103 by pivotally moving the bracket 118 in the direction of arrow B in FIG. 8. The cutter 105 is in the form of a circle partly cut away along a straight line and is connected to a cutter solenoid 120 shown in FIG. 7. The cutter 105 is rotated by the energization of the solenoid 120. The other cutter 106 is positioned as opposed to the cutter 105 with a paid-off portion of he roll paper 92 interposed therebetween. During the rotation of the cutter 105, an edge at the intersection of a plane thereof with a cylindrical surface providing the outer periphery of the cutter 105 comes into frictional contct with an edge of the other cutter 106, whereby the roll paper 92 is cut. The pair of discharge rollers 108, 109 are in pressing contact with each other. The discharge roller 108 at one side is coupled to the feed roller 103 by a train of unillustrated gears and is driven with the feed roller 103. The cutting device 12 has a main motor 122 incorporated therein and serving as a drive source for the foregoing rollers. The main motor 122 is connected to a motor control board 123 (FIG. 7). A drive roller 124 is fixed to the drive shaft of the main motor 122. A single belt 126 is reeved around the drive roller 124 and the drive-side portions of the first clutch 98 and the second clutch 114. Accordingly, when the first clutch 98 is engaged, the transport roller 95 in an idly rotatable state is brought into a driven state, and the torque of the drive roller 124 is delivered to the feed roller 103. When the second clutch 114 is engaged, the feed roller 103 in an idly rotatable state is brought into a driven state, and the torque of the drive roller 124 is transmitted to the feed roller 103. According to the present embodiment, the gear ratios concerned are so determined that the feed roller 103 is driven at twice the speed of rotation of the transport roller 95. Indicated at 128 and 129 in FIG. 8 are tension rollers for the belt 126. On an external suitable portion of the roll paper cutting device 12, a control panel 130 as shown in FIG. 7 is provided. The control panel 130 has ten number entry keys 132, a stop/clear key 134 and a start key 136 as illustrated, and is further provided with a key for selecting a paper feed mode (cassette feed mode or manual insertion mode), a size specifying key for entering the size of sheets to be cut off from the roll paper, a shift start key for starting the shift of the cutting device 12, etc. Using some of the number entry keys 132 on the control panel 130, the desired roll paper transport speed can be set and input to the control system 90 as will be described later. As shown also in FIG. 8, the device has inside thereof a first switch 138 so positioned as to contact the cover 100 when the cover 100 is closed, and second and third switches 139 and 140 arranged upstream from the cutters 105, 106 and downstream from the discharge rollers 108, 109, respectively. The switches 139, 140 are turned on and off by the roll paper 92 when the paper passes the position of the switch. Pulse plates 97, 142 are secured to the respective shafts fixedly carrying the transport roller 95 and the feed roller 103. Rotation detectors 143, 144 (FIG. 7), each comprising a light-emitting element and a photodetector, are positioned in corresponding relation with slits in the respective pulse plates 97, 142. These rotation detectors 143, 144 and the switches 138 to 140 feed detection signals to the control system 90. The control system 90 comprises a CPU 146, ROM 148 and RAM 150 and carries out the following control operations mainly. (a) Based on a signal representing the transport speed input according to hexadecimal notation by some number entry keys 132 on the control panel 130, the CPU 146 writes data as to the transport speed in the RAM 150 and feeds to the motor control board 123 a motor clock signal corresponding to the data to control the speed of rotation of the main motor 122. More specifically, the speed of the motor is controllable by varying the frequencey or duty ratio of the motor clock signal. The gear ratio or the like of the drive system within the cutting device 12 is made equal to the gear ratio or the like of the drive system in the main body of the copying machine, 10. When data as to a speed equal to the speed of transport of copy paper in the machine body 10 is entered by the number entry keys 132, the speed of transport by the transport roller 95 is made equal to the transport speed in the main body 10. (b) The drive motor 82 is started upon the depression of the shift start key on the control panel 130 and stops the drive motor 82 upon the rotation amount detector 88 detecting a predetermined number of pulses after the start of the motor 82. The predetermined pulse number corresponds to the distance from the upper limit position (feed position indicated in solid line in FIG. 1) of the cutting device 12 to the lower limit position (standby position indicated in phantom line in FIG. 1) thereof. The upper limit position is such that in this position, the outlet 110 of the device 12 is in register with the copy paper inlet 28 of the copying assembly 14. (c) In response to the detection signals from the first switch 138, the third switch 140 and the rotation detector 144, the control system feeds motor on and off signals and motor clock signal to the motor control board 123, and turns on and off the clutches 98, 114 and the cutter solenoid 120 with specified timing. The timing will be described in detail later with reference to the flow charts of FIGS. 9 and 10. (d) When the second switch 139 is turned on, a display 152 provided in the vicinity of the control panel 130 is turned on, notifying the user that the roll paper 92 is set in position. Next with reference to the flow charts of FIGS. 9 and 10, a description will be given of the control operation to be actually performed by the control system 90 and the resulting paper feed operation by the device. FIG. 9 shows the operation for feeding the roll paper 92, and FIG. 10 shows a preparatory operation before the start of the feed operation (i.e., step S1 of FIG. 9). First, the copying machine main body 10 is set in the manual insertion mode, in which copy paper is fed from the copy paper inlet 28. The roll paper cutting device 12 is allowed to stand as it is if the device is in its upper limit position where the outlet 110 of the device 12 is in register with the inlet 28. If the device 12 is in its lower limit position, the shift start key on the operation panel 130 is depressed, whereby the device 12 is driven upward in its entirety by the drive motor 82, allowing the rotation amount detector 88 to produce a pulse signal. Upon the predetermined number of pulses have been counted up, the motor 82 is deenergized, whereby the device 12 is automatically brought to a halt at the upper limit position, i.e., at the feed position. On the other hand, when the device 12 is in its standby position away from the position where the copy paper guide plate 62 is attached, the guide plate 62, which is unfolded outward under gravity, is in the guide position where the lower surface of the guide plate 62 is in bearing contact with the restraining portion 651 of the support plate 65 as seen in FIG. 11. Accordingly, the copy paper discharged from the copying assembly 14 falls onto the guide plate 62 and is guided by the plate 62 to a specified position on the stocking tray 61. When the cutting device 12 moves upward from the standby position to the feed position, the guide plate 62 is pushed up from below by the device 12 and automtically folded from the guide position (phantom-line position in FIG. 1) to the retracted position indicated in solid line in FIG. 1. With the cutting device 12 thus brought to the upper limit position, some of the number entry keys 132 on the operation panel 130 of the device 12 are manipulated to input data as to the roll paper cutting size and roll paper transport speed to the control system 90. The data as to the transport speed is the same as the data representing the copy paper transport speed of the copying machine main body 10. In this state, the preparatory operation for paper feeding shown in FIG. 10 is conducted. First, the cover 100 of the cutting device 12 is opened, and the pivotal bracket 118 is moved in the direction of arrow B in FIG. 8 to move the feed roller 104 out of pressing contact with the feed roller 103, and the leading end of the roll paper 92 wound around the roll shaft 93 is manually inserted through a space between the feed rollers 103, 104 (step SS1). The leanding end is brought to the position of the second switch 139, turning on the switch 139 (YES for step SS2), whereupon the display lamp 152 of the device 12 goes on (step SS3). The operator then discontinues the roll paper setting procedure, and returns the pivotal bracket 118 to bring the roller 104 into contact with the roller 103. The cover 100 is thereafter closed (step SS4), whereby the first switch 138 is turned on (YES in step SS5), feeding a detection signal to the control system 90, whereupon the system 92 feeds a control signal to the motor control board 123 to rotate the main motor 122 in the forward direction and drive the drive roller 124 clockwise in FIG. 8 (step SS6). The second clutch 114 is further engaged (step SS7). Consequently, the feed roller 103 and the discharge roller 108 are driven counterclockwise in FIG. 8, pulling out the roll paper 92 in the feed direction. At this time, the main motor 122 is driven at a transport speed lower than the speed input by the number entry keys 132. The roll paper 92 thereafter passes between the discharge rollers 108, 109 and reaches the third switch 140 to turn on the switch 140 (YES in step SS8), whereupon the resulting detection signal is fed to the control system 90, which in turn disengages the second clutch 114 (step SS9). This discontinues the transport of the roll paper 92. Subsequently, the control system 90 reversely rotates the main motor 122 to drive the drive roller 124 in a direction opposite to the above (step SS10), and further engages the first clutch 98 (step SS11), whereby the transport roller 95 is rotated clockwise in FIG. 8 to draw back the roll paper 92 downward. At this time, the pulse plate 97 rotating with the transport roller 95 and the rotation detector 143 feed to the control sytem 90 data as to the rotation of the transport roller 95 as a pulse signal. Upon the number of pulses of this signal reaching a predetermined pulse number M0 (YES in step SS12), the control system 90 disengages the first clutch 98 (step SS13) and deenergizes the main motor 122 (step SS14). The pulse number M0 is so determined as to correspond to the distance of the position of cutting by the cutters 105, 106 from the detection position of the third switch 140, so that the operation of steps SS10 to SS14 stops the leading end of the roll paper 92 accurately at the position where the paper is to be cut by the cutters 105, 106. Some of the number entry keys 132 are thereafter manipulated on the control panel 130 to enter a pulse number M corresponding to the desired size to which the roll paper is to be cut (step (SS15), whereby the preparation for feeding is completed. The subsequent paper feed operation to be performed by the device 12 will be described with reference to the flow chart of FIG. 9. After the completion of preparation (step S1) described above, the start key 136 on the control panel 130 shown in FIG. 7 is depressed (step S2), causing the control system 90 to feed a motor on-off signal and motor clock signal to the motor control board 123 to forwardly drive the main motor 122 at a high speed (step S3). The term "high speed" as used herein corresponds to the roll paper transport speed entered by the number entry keys 132, and the motor clock signal corresponding to this speed is fed to the control board 123. If the first clutch 98 is engaged, the above signals cause the transport roller 95 to rotate at a speed equal to the copy paper transport speed of the copying assembly, or if the second clutch 114 is engaged, the feed roller 103 is rotated at twice the speed of the transport roller 95. In the above state, the control system 90 first engages the second clutch 114 (step S4), whereby the feed roller 103 is driven counterclockwise in FIG. 8, delivering the roll paper 92 from the outlet 110 into the inlet 28 of the copying assembly 14. At this time, the rotation of the feed roller 103 is detected by the pulse plate 142 and the rotation detector 144. Upon the pulse number of the detection signal reaching a predetermined pulse number M1 (YES in step S5), the second clutch 114 is disengaged (step S6) to discontinue the transport of the roll paper 92. The pulse number M1 corresponds to the distance of the pair of feed rollers 22 from the cutting position of the cutters 105, 106, so that the operation of steps S4 to S6 brings the leading end of the paper 92 to the position of the pair of feed rollers 22 of the copying assembly 24. Next, the control system 90 engages the first clutch 98 (step S7), thereby driving the transport roller 95. The rotation is detected by the rotation detector 143. Upon the pulse number of the detection signal reaching a predetermined pulse number M2 (YES in step S8), the first clutch 98 is disengaged (step S9) to stop the rotation of the roller 95. The operation of steps S7 to S9 rotates the transport roller 95 only, warping the paper at its portion upstream from the feed rollers 103, 104. The rollers are now in an idly rotatable state, ready for the start of feed of paper for the machine main body 10. The feed rollers 22 in the machine body 10 thereafter operate, starting to feed the roll paper 92, whereby the portion of the roll paper 92 within the device 12 is pulled upward and rotates the feed roller 103 by contact therewith. When this rotation is detected by the rotation detector 144 (YES in step S10), the control system 90 engages the first clutch 98 (step S11) to rotate the transport roller 95. Upon the pulse number of the detection signal 144 from the detector 144 reaching a predetermined pulse number M3 (YES in step S12), the first clutch 98 is disengaged (step S13). The pulse number M3 is the pulse number corresponding to the size of sheet to be cut off from the roll paper 92 and set on the operation panel 130, minus a number of pules, m, that is, M - m. Accordingly, the operation of steps S11 to S13 transports the roll paper 92 within the device 12 a distance corresponding to the pulse number M3, i.e., M - m, at a speed equal to the feed speed in the machine body 10. Subsequently, the control system 90 engages the second clutch 114 (step S14), rotating the feed roller 103, and disengages the second clutch 114 (step S16) upon the pulse number of the detection signal from the rotation detector 144 reaching a predetermined pulse number M4 (YES in step S15). The pulse number M4 is the value m. Accordingly, the operation of steps S14 to S16 transports the roll paper 92 within the cutting device 12 a distance corresponding to the pulse number M4 (= m) at twice the feed speed in the machine main body 10. Consequently, the roll paper 92 is transported forward excessively by a distance corresponding to one-half of the pulse number m, forming a warped portion upstream from the cutters 105, 106 so as to be cut with proper timing. Next, the control system 90 energizes the cutter solenoid 120 only for a predetermined period of time (step S17) to rotate the cutter 105 one turn and cut the roll paper 92. The rear end of the cut sheet of the roll paper 92 thereafter moves past the third switch 140 and turns off the switch 140 (YES in step S18), whereupon the system deenergizes the main motor 122 (step S19) to complete the feed operation. While the roll paper 92 is fed by the above operation using the cutting device 12, paper may be fed manually to the machine main body 10 through the copy paper inlet 28 without using the cutting device 12. In this case, the shift start key on the operation panel of the device 12 is manipulated to lower the device 12 to its lower limit position, whereby the inlet 28 is exposed at the front side of the machine body 10 and made ready for use. Paper can then be manually inserted into the inlet 28. According to the present embodiment described, the roll paper cutting device 12 is attached to the copying machine main body 10 so as to be vertically movable between the upper limit position in which the outlet 110 of the device 12 is in register with the copy paper inlet 28 and the lower limit position in which the outlet 110 is away from the inlet 28. The roll paper 92 can be fed by the device 12 as positioned in the upper limit position to the machine main body 10 which is an existing copying machine. With the device 12 shifted from the upper limit position to the lower limit position, paper can be fed in the conventional manner utilizing the manual insertion feed mechanism usually incorporated in the main body 10 of the image forming apparatus. Further according to the present embodiment, the copy paper guide plate 62 is shiftable between the guide position and the retracted position with the vertical movement of the cutting device 12, such that even if the guide plate 62 is located at the feed position for the cutting device 12, the device 12 can be driven vertically free of trouble. The roll paper cutting device 12 of the present embodiment has the following advantages. (a) The cutting device 12 has the rotation amount detector 88 for detecting the amount of shift of itself and the control system 90 and therefore has the advantage of being automatically movable singly to an appropriate position without being controlled by the copying machine main body 10. Further because the device 12 can be driven and is operable for feeding paper without conducting signal communication with the machine main body 10, the device 12 has improved optionality for use with the machine main body 10. However, the device 12 can be made satisfactorily movable up and down by drive means provided in the machine main body 10. (b) The cutting device 12 can be set to a desired roll paper transport speed by feeding data as to the speed to the control system 90 by means of the control panel 130, so that when the speed is determined in accordance with the copy paper transport speed in the machine main body 10 to which the device is attached, the roll paper within the device 12 can be transported to the interior of the main body 10 at a stabilized speed. Thus, the device 12 is usable for the machine main body 10 at widely varying copy paper transport speeds for supplying the roll paper to the machine body 10 free of trouble. With the foregoing embodiment, the transport roller 95 is driven at the same speed as the set speed, and the feed roller 103 is driven at twice the set speed, whereas the relationship between the speed set by the transport speed input means and the speed of transport of the roll paper by the transport rollers may be determined suitably according to the structure used. (c) With the roll paper cutting device 12, the roll paper 12 set in place is first transported to a position downstream from the cutters 105, 106 and then reversely transported by a distance corresponding to the predetermined pulse number M0 upon the leading end of the paper reaching the delivery position of the third switch 140. Accordingly, the leading end of the roll paper 92 can be brought to the cutting position more accurately than conventional devices wherein the paper leading end is brought to the specified position manually. The reverse transport serves to eliminate the warped portion of the paper between the roll portion of the paper 12 and the feed rollers 103, 104. This leads to the advantage of reducing the load on the drive system when starting the feeding operation. The paper leading end can be positioned in place by the following modifications. (1) Although the cutting device 12 is attached to the machine main body 10 vertically movably according to the foregoing embodiment, the cutting device 12 may be used independently of the machine body 10 for cutting the roll paper 92 for the machine body 10 to use the cut sheets. Even in this case, the same advantage of automatic leading end positioning as above is available. The cut sheets of roll paper 92 are of course not limited to use for copying machines. (2) The leading end of the roll paper 92 is positioned at the cutting position of the cutters 105, 106 according to the foregoing embodiment, whereas this position is not limitative but may be determined suitably. However, if the leading end is placed at the cutting position, the roll paper can be cut into sheets of the same size under the same mode of control from the first sheet. This simplifies the mode of control to be effected by the control system 90. (3) The third switch serving as roll paper sensor means is disposed downstream from the discharge rollers 108, 109 with the above embodiment, whereas the roll paper sensor means needs only to be positioned downstream from the cutting position of the cutters. For example, the sensor means may be interposed between the cutters 105, 106 and the discharge rollers 108, 109. (4) Although the roll paper 92 is positioned in place based on the amount of rotation of the feed roller 103 with the above embodiment, the same advantage as above is also available when the transport of the paper is discontinued upon the lapse of a predetermined period of time after the actuation of the third switch 140. The mount structure for the copy paper guide member of the invention is not limited to the one described above but may be the one shown in FIGS. 12 and 13 as a second embodiment. With reference to these drawings, a pair of opposite guide members 160 is fixed to the upper side of the copy paper stocking tray 61 at its inlet portion. A copy paper guide plate (copy paper guide member) 62 is provided between the two guide members 160 so as to be slidable between a guide position where the guide plate 62 projects from the stocking frame 16 and a retracted position in which the plate 62 is stowed inside the frame 16. A rack 162 extending in the sliding direction is secured to the lower surface of the guide plate 62 and exposed downward through a groove 164 formed in the lower side of the stocking tray 61. A gear 166 in mesh with the rack 162 is rotatably provided within the stocking frame 16, which is also rotatably provided with a gear 168 as partly exposed from the frame 16. The two gears 166 and 168 are coupled together by a belt 170. On the other hand, the cutting device 12 has a rack 172 extending vertically and attached to the upper portion of the side face thereof opposed to the stocking frame 16. The rack 172 is meshable with the gear 168. As shown in FIG. 12, the position of the guide plate 62 is so determined that when the gear 168 is in mesh with the upper end of the rack 172, the gear 166 meshes with the base end of the rack 162 (left end thereof in FIG. 12). When the cutting device 12 is in its standby position with the gear 168 meshing with the upper end of the rack 172 on the device 12 as indicated in solid line in FIG. 12, the guide plate 62 is projected out from the stocking frame 16 for guiding the discharged copy paper onto the stocking tray 61. When the cutting device 12 moves upward from the above state, the upward movement of the rack 172 on the device 12 is converted to sliding movement of the guide plate 12 by means of the gear 168, belt 170, gear 166 and rack 162, whereby the guide plate 62 is brought to the retracted position as stowed in the stocking frame 16 (see the phantom-line position in FIG. 12). Accordingly, the guide plate 62 will not interfere with the device 12 when the device moves upward, permitting smooth shift of the device 12 to the feed position. Alternatively, the guide plate 12 may be driven by a motor or the like provided therefor, as controlled by the shift of the cutting device 12. Next, a third embodiment will be described with reference to FIG. 14. With the foregoing embodiments, the cutting device 12 is driven singly by itself independently of the machine main body 10, whereas according to the third embodiment, the control system 260 incorporated in the copying machine main body 10 is utilized for controlling the device 12 for driving. The machine main body 10 has a control panel 262 which is adapted to select a roll paper feed mode in addition to the manual insertion mode and cassette feed mode. The main body control system 260 receives instruction signals from the control panel 260 and detection signals from the aforementioned paper absence switch 52, cassette insertion switch 54 and jam sensor switches 56 to 59 for effecting control in response to the signals. More specifically, the control system feeds a control signal to the drive motor 82 in one of the cases given below to drive the cutting device 12 downward from the upper limit position to the lower limit position and gives an alarm through a display 264. (1) When the manual insertion mode is selected on the control panel 262. (2) When the paper absence switch 52 detects absence of copy paper in the cassette 18. (3) Upon the detection of a jam by one of the jam sensor switches 56 to 59. The present embodiment has the following advantages. (1) When the manual insertion mode is selected on the control panel 262, the cutting device 12 automatically descends to expose the copy paper inlet 28 on the front side, so that the operator can start to feed paper manually without following any other procedure. (2) In the case where the paper absence switch 54 detects the absence of copy paper inside the cassette 18, the cutting device 12 automatically descends away from the location of withdrawing the cassette 18, so that the cassette 18 can be withdrawn for the replenishment of copy paper immediately without following any other procedure. (3) Upon one of the jam sensor switches 56 to 59 detecting a jam, the cutting device 12 automatically descends away from the unit housing 60, with the result that the housing 60 can be immediately withdrawn toward the front for remedying the jam without following any other procedure. The first to third embodiments can be modified as follows. (1) Although the roll paper cutting device 12 is attached to the copying machine main body 10 movably upward and downward according to the foregoing embodiments, the device 12 needs only to be shiftable between the feed position and a position away from the feed position according to the present invention. Insofar as this requirement is fulfilled, the device 12 may be attached to the machine main body 10, for example, horizontally movably, or attached to the body 10 at the feed position. (2) The drive motor 82 drives the cutting device 12 according to the above embodiments, whereas other drive means is usable according to the invention, or the device 12 may be moved manually. Furthermore, the drive means, the shift amount detecting means, and control means may be provided in the main body of the image forming apparatus. (3) The first embodiment may be so modified that the cutting device 12 has incorporated therein not only the drive means therefor but also the guide rails 64 or like guide means, for example. The device 12 is then attachable to the image forming apparatus with greater ease and becomes more useful as an optional device. (4) According to the third embodiment, the cutting device is so controlled as to be automtically shifted when the manual insertion mode is selected or upon an abnormality such as a jam or absence of paper is detected. However, when the cutting device is made manually shiftable relative to the image forming apparatus, means needs only to be provided for notifying the operator of the need to shift the cutting device in these cases. The notice, if given, then eliminates the likelihood that the operator will forget to shift the cutting device to the standby position prior to the manual insertion mode (second feed mode), thus resulting in a remarkably improved efficiency for paper feeding. Further the abnormalitities to be detected are not limited to those mentioned above. For example, toner absence detecting means may be provided for indicating a reduction in the amount of developer within the developing unit 32 so as to drive the device or give notice when the absence of toner is detected. (5) Although the manual insertion mode has been described with reference to the foregoing embodiment as an example of mode wherein copy paper is fed from the inlet 28 by means other than the cutting device 12 (i.e. second feed mode), the second feed mode is not limited to the manual mode. For example, the inlet 28 can be provided with a paper cassette. Although the present invention has been fully described by way of example with reference to the accompanying drawings, it is to be understood that various changes and modifications will be apparent to those skilled in the art. Therefore, unless otherwise such changes and modifications depart from the scope of the invention, they should be construded as being included therein.

Claims: An image forming apparatus for forming an image on a sheet inserted via a sheet inlet (28) on a main body (10) of the apparatus, having a paper sheet cutting device (12) for a paper roll (92) adapted to cut a sheet from the roll and discharge the cut sheet via an outlet (110) of the device, the cutting device being displaceably locatable relative to the apparatus main body (10) in a feed position where the outlet (110) is in register with the sheet inlet (28), characterised in that the cutting device (12) comprises drive means (82) for displacing the cutting device selectively relative to the main body (10), between said feed position and a standby position and guide means (64) are provided on the main body for guiding the cutting device vertically between said feed and standby positions. An image forming apparatus as defined in claim 1 which comprises means (88) for detecting the displacement of the cutting device between said locations, and control means (90) for controlling the operation of the drive means based on the displacement detected. An image forming apparatus as defined in claim 2, wherein the cutting device (12) comprises the means (88) for detecting the amount of displacement of the device, and the control means (90) for controlling the operation of the drive means (82) in dependence upon the amount of displacement detected. An image forming apparatus as defined in any one of the preceding claims, wherein the roll paper cutting device is attached to the apparatus main body so as to be displaceable between the feed position and the standby position. An image forming apparatus as defined in any one of the preceding claims, comprising mode input means for selecting as a paper feed mode a first feed mode wherein paper is fed from the cutting device or a second feed mode wherein paper is fed through the sheet inlet by means other than the cutting device. An image forming apparatus as defined in claim 5, wherein the second feed mode is a manual insertion mode wherein sheets are inserted from the sheet inlet. An image forming apparatus as defined in any one of the preceding claims which comprises means (52,56-59) for detecting an abnormality in the image forming apparatus, and means operable upon the detection of said abnormality to notify the operator or to actuate the displacement of the cutting device to the standby position. An image forming apparatus as defined in claim 7, wherein the apparatus main body (10) has a sheet container (18) and is adapted to form an image selectively on a sheet inserted from the sheet inlet (28) or a sheet fed from the sheet container, the cutting device (12) being shiftable between the feed position where the outlet of the device is in register with the sheet inlet of the apparatus main body and the standby position where said outlet is away from the location of withdrawal of the sheet container, and the abnormality detecting means are means (52) operable by the absence of sheets in the container. An image forming apparatus as defined in claim 7 or claim 8, wherein a portion (60) of the apparatus main body (10) is withdrawable to remedy jams with the withdrawn portion, and the cutting device (12) is shiftable between the feed position where the outlet of the device is in register with the sheet inlet of the apparatus main body and the standby position wherein the outlet is away from the location of withdrawal of the main body portion, the abnormality detecting means comprising means (56-59) for detecting a jam occurring in the apparatus main body. An image forming apparatus as defined in any one of the preceding claims, wherein the main body (10) is provided with a sheet guide member (62) shiftable between a guide position in which the guide member projects out from the main body to guide sheets to a sheet holding means (61) when the cutting device is in the standby position and a retracted position when the device is in the feed position. An image forming apparatus as defined in claim 10, wherein the sheet guide member (62) is pivotally movable about its lower end between the retracted position and the guide position, and a holding member (651) is provided for holding the sheet guide member in the feed position. An image forming apparatus as defined in claim 10 or claim 11, wherein the sheet guide member (62) is disposed at a position permitting the guide member to be held in the retracted position by the cutting device (12) when the device is in the feed position and permitting the guide member to return to the guide position when the cutting device is in the standby position. An image forming apparatus as defined in claim 10, wherein a drive conversion mechanism (162-172) is provided for converting the displacement of the roll cutting device to the displacement of the sheet guide member, positioning the sheet guide member in the retracted position when the cutting device is in the feed position and positioning the sheet guide member in the guide position when the cutting device is in the standby position. An image forming apparatus as defined in any one of the preceding claims, wherein the cutting device (12) is provided with a copy paper discharge tray (99) for receiving copy paper discharged from the apparatus main body when the cutting device is in the feed position. A sheet paper cutting device (12) separably attachable to an apparatus (10) for forming an image on a sheet inserted via a sheet inlet on a main body of the apparatus, the cutting device comprising means to cut a sheet from a paper roll and discharge the cut sheet via an outlet (110) of the device to the inlet (20) on the main body of the image forming apparatus, the paper sheet cutting device further comprising means arranged to cooperate with means on the apparatus for location of the cutting device thereon, characterised in that the cutting device comprises drive means (82) for displacing the cutting device to adjust the cutting device selectively on the apparatus relative to the main body between a feed position where the outlet (110) is in register with the sheet inlet (28) or a standby position where the outlet (110) is out of register with the sheet inlet (28). A sheet paper cutting device according to claim 15 comprising means (88) for detecting the displacement of the cutting device between said locations, and control means (90) for controlling the operation of the drive means based on the displacement detected. A sheet paper cutting device according to claim 15 or claim 16 provided with a copy paper discharge tray (99) for receiving copy paper discharged from the apparatus main body when the cutting device is in the feed position.

Inventors: FUKANO MASAHIKO CITY-PLAZA-MIK, GOTOH EIJI, KAJITA HIROSHI, KONDOH AKIHIRO, MATSUO TAKESHI, NISHIOKA NOBUHIRO, SUGIURA MAKOTO, TANAKA SATOSHI, FUKANO, MASAHIKO, CITY-PLAZA-MIKUNIHONMACHI 301, GOTOH, EIJI, KAJITA, HIROSHI, KONDOH, AKIHIRO, MATSUO, TAKESHI, NISHIOKA, NOBUHIRO, SUGIURA, MAKOTO, TANAKA, SATOSHI
Applicants: MITA INDUSTRIAL CO LTD, MITA INDUSTRIAL CO. LTD.
Application year: 1990
Main classification: G03G15
IPC codes: G03G15