Image forming apparatus

Abstract: Near a discharge means (48) for discharging paper (P) with an image formed thereon, there is provided a punching means (7) for punching holes. The drive of the discharge means (48) is scontroled to punch holes in the trailing portion of the paper (P), without causing crease and tear or change in the quality of the paper (P). Said punching means (7) includes punching cutters (72) and a punching die (74). The punching cutters (72) and the punching die (74) are provided in a unit (U) which can be drawn out of a casing (1) covering the punching means (7). With the unit (U) drawn out of the casing (1), jam recovery can be easily executed. The unit (U) is moved in the width direction of the paper (P), thereby to adjust a position of punch holes. A collecting box (76) for collecting paper scraps (P1) is disposed in the unit (U). If the collecting box (76) is turned or the opening (76a) thereof is lifted up when the unit (U) is turned, the paper scraps (P1) therein will not fall off. Delaying timing for plural punching cutters (72) to punch holes can reduce load on the drive system.

Description: Image Forming Apparatus The present invention relates to an image forming apparatus applying the electrophotographic process, such as an electrostatic copying apparatus or a laser beam printer, more specifically, to an image forming apparatus provided with a punching function for punching holes to file paper whereon image has been formed. As an apparatus for forming electrophotostatic latent image on the surface of a copy paper by means of the electrophotographic process, there have been proposed variety of types which is added with a punching function geared with the operations of the apparatus automatically to punch holes for filing in the paper. In electrophotographic process, a copy paper is processed by producing an electrostatic latent image formed on the surface of a photosensitive material and by transferring the image thereon, and the image processing is followed by fusing the transferred image by heating and such. An image forming apparatus according to the preamble of claim 1 is known from JP-A-58 140 775. The English abstract of this document discloses a punch mechanism by which the forward end of a sheet is detected by a photosensor, which in turn actuates a stopper. A clutch disconnects a conveying roller at the same time as a signal is received from the photosensor. There are no timing means provided to output a signal to stop the discharge means after an adjustable time period from receiving a signal from a sensor. Moreover, the reference gives no suggestion of such timing means. Technically, the arrangement with punch mechanism disclosed there would also not require a timing means. The front edge of the sheet is detected and the position of the puncher and stopping means are all fixed, so that a variation in timing would have no purpose. The United States Patent US-A 4 293 366 discloses a machine comprising punching and binding mechanisms. A punch platen on which papers to be punched are supported is positioned relative to a punch throat. The platen serves as a die plate with holes formed therein. A punch plate is provided with a number of pins corresponding to the number of holes in the die plate. Actuators trigger the electrical circuitry to actuate the punching mechanism, the actuators activating switches located on a slide extending to the throat. The slide may be moved forwardly and rearwardly to control the spacing from the spine edge of the paper. Movement of the slide controls the spacing of the apertures punched in the paper. The punch mechanism is motor-driven by a punch motor which has extended shafts having eccentric cranks at both ends. As the motor turns, the eccentric cranks cause a vertical lever to reciprocate the punch plate and the pins which are lined with the holes in the die plate. The paper in the throat is then punched at the preset spacing from the spine edge of the paper. In general, image forming apparatus having a punching function may be roughly divided into two types; one type is to punch holes in copy paper in advance to the image processing and another type is to punch holes after the image processing and fusing. In the former type, paper crumbs made by punching may give bad influence to form the image. Accordingly, the latter type apparatus wherein holes are punched after the image processing and fusing has become increasingly popular. The image forming apparatus generally employs a punching means provided with punching cutters movable along a paper delivery passage and with a punching die for introducing the punching cutters which is disposed in the delivery passage, opposing the punching cutter. When the punching means punches holes in the paper, the paper must to be temporarily halted in the paper delivery means. According to the conventional methods of temporarily halting the paper, the leading edge of the paper is adapted to hit a stopper or a discharge roller for carrying the paper out of the apparatus is temporarily stopped. However, the apparatus of the above-mentioned composition may cause crease or fold in the paper, if the paper is halted with the trailing portion thereof caught in an always rotating discharge roller which is disposed in a discharge passage. In addition, if the paper is halted with the trailing portion thereof caught in a fusing unit for heating and fusing a transferred image on the paper, the portion caught in the fusing unit may be excessively heated, resulting in changing in the quality of the paper. To prevent the crease and fold in the paper, and changing the quality of the paper with heating, there has been proposed image forming apparatus, wherein a punching function H for punching holes is disposed near a paper discharge port Y1 in the paper delivery means Y, and a halting portion for halting paper P curved as shown by the dot-and-dash line in Fig. 37 is provided between the punching function H and the always rotating delivery roller Y2 (described in JP-A-140755/1983). The punching device H includes; a punching means X comprising punching cutters X1 and a punching die X2 having through-holes X2a for introducing the punching cutters; a stopper H1 for the leading edge of the paper P to hit; and a discharge roller H2 which stops rotating when the punching means X punches holes. In this Fig., the mark H3 represents a sensor, which detects the leading edge of the paper P, protrudes the stopper H1 as illustrated in this Fig. with a black arrow and stops the rotation of the discharge roller H2. X3 represents cams which rotates on a rotary shaft X3a to move the punching cutters X1 up and down. According to the above mentioned image forming apparatus, if the paper P is so large that the paper P is halted by the stopper H1 and the discharge roller H2 with the trailing portion thereof caught in in the delivery roller Y2, the delivery roller Y2 keeps rotating to push forward the trailing portion of the paper P to curve it as illustrated with dot-and-dash line in Fig.37. Since the paper P is halted in the halting portion Z in this manner, crease or fold on the paper P can be prevented. For preventing crease or fold on the paper halted in the halting portion Z, the paper should be gently curved as shown in the Fig.37. This requires a large space for the halting portion Z in the vertical and the delivery passage directions, accordingly it is impossible to miniaturize the image forming apparatus. When paper crumbs are caught in the punching locks, the punching cutter X1 cannot withdraw causing paper jam therein. When a paper jam in other parts stops the image forming apparatus with the punching cutter X1 pushed down by the cam X3, a jam recovery process should be easily executed in a conventional image forming apparatus having a punching function. To meet this need, there has been proposed an image forming apparatus provided with a punching means X, wherein, as shown in Fig. 38, a punching die X2 also serving as a guide plate of the bottom side of a paper delivery means Y can be turned downward to open the paper delivery means Y (described in JP-U, A-193698/1988). The above-mentioned structure, however, requires a space large enough to turn the punching die X2 open for executing jam recovery under the punching means X, and therefore it is difficult to miniaturize the apparatus. Furthermore, the jam recovery operation is difficult, because a user must remove jam looking up into the paper delivery means Y, which is far below the eye-level of the user. In addition, when paper crumbs are caught between the punching cutters X1 and the through-hole X2a in the punching die X2, it is difficult to open the punching die X2, the jam recovery is more troublesome. Every image forming apparatus should punch holes at the same position in the paper. But in fact, every apparatus punch holes at any position shifted in the width direction of the paper. The shift stems from, for instance, very low assembly tolerances in manufacturing the image forming apparatus. As shown in Fig. 39, an image forming apparatus with a punching function normally has a collecting box K to collect paper scraps left after punching holes. The box which is disposed beneath the punching die X2 in the punching means X. To remove the paper scraps left after the punching, however, the user must take the trouble to open the main body of the apparatus and to remove the scraps. To facilitate the removal of the paper scraps, it is suggested to dispose the collecting box K at upper side of a unit, which turns or moves parallel in one piece thereby the box drawn out of the main body of the apparatus. However, in the structure wherein the unit moves parallel to be drown out, it is not easy to take out the collecting box, because the collecting box K is further under the punching means which is far below the eye-level of the user. On the other hand, in the structure wherein the box is turned around a shaft disposed under the unit, the collecting box K can be easily taken out because the box is exposed on the upper side of the unit. However, the paper scraps in the box may fall out because the box turns along with turning the unit. It is normally required to punch two or more holes at regular interval in the width direction of the paper which is carried in the paper delivery means. As shown in Fig. 40 and 41, cams X3 connected to a driving source (not shown) of the image forming apparatus rotates on a rotary shaft X3a, vertically moving a plurality of punching cutters X1(two cutters in Fig.41). Thus, the cutters punch two or more holes at a time (described in JP-A-260965/1985). As described above, the punching means X punches two or more holes at a time by using the punching cutters X1 and therefore a great load is is required from the driving source when punching holes. This may affect driving of the other parts of the image forming apparatus; if an image forming process is executed on another sheet of paper when the holes are punched, a deviated image may be formed. When the holes are punched in hard paper such as cardboard in particular, malfunction may occur such as disengagement of a pulley from a timing belt used to transmit the driving force from the driving source to the rotary shaft X3a of cams X3, breakage of the gear used for the transmission, or bending of the rotary shaft X3a. Hence, it is required to make the transmission components or the rotary shaft X3a with materials of higher rigidity, or to reinforce the rotary shaft X3a by increasing the thickness thereof. This results in higher production costs or the larger and heavier punching means. An object of the invention is to provide an image forming apparatus which can precisely adjust a punch-hole position in paper. The present invention provides an image forming apparatus as defined in claim 1. Embodiments of the invention are given in the claims 2 to 29. An embodiment of the invention provides an image forming apparatus wherein the punching means includes a plurality of punching cutters disposed at a predetermined interval in the width direction of the paper carried with the paper delivery means , a punching die for receiving these punching cutters , and pushing means to project the punching cutters toward the punching die; the pushing means is supported in a casing covering the punching means; and the punching cutters and the punching die are provided in a unit which is able to be drawn out of the casing. According to a further embodiment of the invention, at least the punching cutters and the punching die can be drawn out of a casing which covers the punching means , and are disposed on a unit movable in the width direction of the paper; and the apparatus includes adjustment means for moving the unit in the width direction of the paper thereby to adjust a position for the punching means to punch holes in the paper. According to a further embodiment of the invention, a collecting box which, being disposed under the punching die, receives paper scraps made by punching holes through an opening formed at the upper portion thereof, and stores the paper scraps therein; at least the collecting box is disposed on a unit which is turnable and can be drawn out of a casing covering the punching means; and the unit is provided with means for always turning the opening of the collecting box upward when the unit is turned. As an advantage of the invention, the discharge roller is controlled to temporarily stop so that paper is halted with its trailing portion positioned in the punching means. When holes are punched, the paper temporarily halts with its trailing portion caught in the discharge roller and with its leading edge protruded out of the image forming apparatus. Accordingly, the paper does not come in contact with the always rotating delivery roller and the heat transferring device disposed in the upstream side of the punching means. The image forming apparatus according to the invention does not cause crease on paper or change in quality when holes are punched. Furthermore, since the punching means can be disposed in the vicinity of other parts of the paper delivery means, a large space is not required and the apparatus can be miniaturized. In still another embodiment of the invention, a unit including the punching cutters and a punching die is able to be drawn out of a casing, is movable in the width direction of a copy paper and is provided with an adjustment means for moving the unit in the width direction of the paper. By moving the unit with this adjustment means, the position for a punching means to punch holes can be precisely adjusted in the width direction of the paper. In further embodiment of the invention, a unit comprising punching cutters, the punching die and the box for collecting paper scraps can be drawn out of a casing by turning the unit. The collecting box can be easily drawn out of the casing, because the collecting box is adapted to be exposed at the upper side of the unit. In addition, since the collecting box is tunably supported in such a manner as to always turn upward when the unit is turned, or an elastic member attached to the unit holds the opening of the collecting box always turned upward when the unit is turned, paper scraps contained in the box does not fall off. In still further embodiment of the invention, timing to punch a hole is delayed for each punching cutter and hence load on the driving system of an image forming apparatus is reduced, in comparison to a type wherein plural holes are punched at a time. The load thus reduced will not affect driving of the image forming apparatus. In addition, because it is not necessary to reinforce the transmission function of driving force, manufacturing costs can be reduced and besides the image forming apparatus can be made smaller and less heavy. Fig. 1 is a schematic view illustrating the internal structure of an electrostatic copying apparatus as an embodiment of an image forming apparatus according to the present invention. Fig. 2 is a perspective view showing a state when a unit is turned and drawn out of the casing of the copying apparatus in the embodiment. Fig. 3 is a perspective view showing a state when the unit is pressed in a casing. Fig. 4 is a perspective view showing a modification of a window. Fig. 5 is a sectional view illustrating the internal structure of the unit. Fig. 6 is a perspective view showing a modification of a drive control means for controlling the drive of the discharge means. Figs. 7 to 9 are sectional views illustrating the operation of the punching means in the embodiment. Fig. 10 is a side view of the punching means. Fig. 11 is a plan view showing a punching die and paper holders in the punching means. Figs. 12 and 13 are sectional views illustrating modifications of the punching means. Figs. 14 to 16 are sectional views illustrating modifications of the unit. Figs. 17 and 18 are sectional views showing other modifications of the unit. Figs. 19 and 20 are sectional views illustrating other modifications of the unit. Fig. 21 is a perspective view showing a state when a unit is turned and drawn out of the casing in an embodiment provided with the unit movable in the width direction of paper. Fig. 22 is a sectional view of the unit in the embodiment. Fig. 23 is an enlarged sectional view showing the main portion of the unit. Fig. 24 is an enlarged sectional view showing a modification of an adjustment means for moving the unit. Figs. 25 to 30 are perspective views showing modifications of a punching means provided with a function to delay timing to punch holes with punching cutters. Figs. 31 and 32 are sectional view illustrating the main portion of an embodiment wherein a box for collecting paper scraps is tunably supported in the unit. Fig. 33 is a perspective view of the collecting box used in the embodiment. Figs. 34 and 35 are sectional views showing the main portion of an embodiment provided with a function to lift up the collecting box with an elastic member. Fig. 36 is a perspective view showing a state when the unit is turned and drawn out of the casing in the embodiment. Fig. 37 to 41 are sectional views showing conventional punching mechanisms. Protection is sought only for the embodiments covered by the claims. Fig. 1 shows the whole body of an electrostatic copying apparatus as an embodiment of an image forming apparatus according to the present invention. The electrostatic copying apparatus comprises a casing 1, wherein an optical system 2, an image forming means 3, a first paper delivery means 4, a second paper delivery means 5, an intermediate tray 6 and a punching means 7 are included. On the upper part of the casing 1, there are provided a transparent plate 11 on which a document to be copied (not shown) is set, and a document holder 12. The optical system 2 includes a light source 21, mirrors 22, 23, 24, lens 25 and mirror 26. The optical system 2 exposes a document set on the transparent plate 11 with the light source 21, and conduct the reflected light from the document with mirrors 22, 23, 24, lens 25 and mirror 26 to the image forming means in 3, as shown with dot-and-dash line in the Fig. The image forming portion 3 comprises a photosensitive drum 31 rotating in one direction, and a corona discharger 32, a developing device 33, a transferring corona discharger 34, a separating corona discharger 35 and cleaner 36 which are disposed around the photosensitive dram 31. The image forming process in the image forming portion 3 is executed in the following order. The surface of the photosensitive drum 31 is uniformly charged by the corona discharger 32, and on the charged surface of the photosensitive drum 31, the optical system 2 forms a document image to form an electrostatic latent image. Then, toner is electrostatically made to adhere to the electrostatic latent image by the developing device 33 thereby to form a toner image, and the toner image thus formed is transferred on the surface of paper P by the transferring corona discharger 34. Then the paper P on which the toner image is transferred is separated from the surface of the photosensitive drum 31 by the separating corona discharger 35, and the cleaner 36 clears the toner remaining on the surface of the photosensitive drum 31 after separating the paper P from the drum 31. The first paper delivery means 4 comprises feed rollers 41a, 41b, 41c, feed passages 42a, 42b, 42c, a registration rollers 43, a delivery rollers 44, a delivery belt 45, a heat fusion device 46, a delivery rollers 47 and a pair of discharge rollers 48 as a discharge means. The feed rollers 41a, 41b, 41c feed the paper P by a sheet from a paper feed cassettes 13a, 13b or a stacking bypass 14, which is detachably attached to a side portion of the casing 1. The registration rollers 43 and the delivery rollers 44 are fed the papre P from the paper feed cassetes 13a, 13b, or the stacking bypass 14 to the image forming means, timed to the rotation of the photosensitive drum 31. The heat fusion device 46 applies heat and pressure on the surface of the paper P on which an image has been formed in the image forming portion 3, thereby to fuse the toner image on the surface of the paper P. As the punching means 7 punches holes in the trailing portion of the paper P, the discharge rollers 48 are controlled to temporarily halt the paper P with its trailing portion set in the punching means 7. Therefore, when the holes are punched, the paper P temporarily halts with its trailing portion caught in the discharge rollers 48 and with its leading edge protruded from the casing 1. Accordingly, the paper P does not come in contact with the delivery rollers 47 always rotating, and the heat transferring device 46, which are disposed in the upstream side of the punching means 7. As shown with a broken line in Fig. 5, a drive control means for controlling the rotating of discharge rollers 48 as described above, includes a discharge drive system G provided separately from the drive system of the copying apparatus, and a control system C for controlling the discharge drive system G according to a signal from a sensor S. The discharge drive system G includes a stepping motor G1 whose rotation is controlled according to a signal from the unit C, a gear G5 fitted to the lower roller 48b of the pair of discharge rollers 48 and a plurality of gears G2 to G4 for transmitting the rotation of the stepping motor G1 to the gear G5. The stepping motor G1 can rotate not only in the direction to carry paper out of the machine but can also rotate in the direction opposite to the above. As described in later, the motor is also used to rotate the delivery rollers 51a of the second paper delivery means in the forward and reverse directions. In the drive control means, when a sensor S disposed between the heat fusion device 46 and the delivery rollers 47 of the first paper delivery means 4 detects the trailing portion of the paper P discharged from the heat fusion device 46 after an image has been fused it. According to the detecting signal, the control system C stops the rotation of the stepping motor G1 to temporarily halt the drive of the discharge rollers 48, while the trailing portion of the paper P staying in the punching means 7. When the punching means 7 punches holes near the trailing edge of the paper P, the control system C starts the stepping motor G1 to drive the discharge rollers 48 again. Thus the paper P wherein holes have been punched is discharged onto a copy receiving tray 15 disposed outside of the copying apparatus. As shown in Fig. 6, the drive control means may include an electromagnetic clutch K disposed between any one J1 of the drive shafts of the drive system of the copying apparatus and one 48b of the pair of discharge rollers 48, and a control system C for switching the clutch K according to the signal from the sensor S. The timing to temporarily stop the discharge rollers 48 when the sensor S has detected the trailing portion of the paper P can be set according to the following means: a timer which starts measuring time when the sensor S detects the trailing portion of the paper P, and which outputs a signal when it determines the expiration of a predetermined period of time. A pulse counter which converts the rotation of the discharge rollers 48 and such, into pulses by means of a rotary encoder and the like, and which outputs a signal when it has counted the pulses to a predetermined count. A timer or pulse counter having an adjustment function for adjusting a predetermined time or a predetermined amount of pulses before outputting a signal also can be used as the means. The timer or pulse counter having the adjustment function may serve as an adjustment means for adjusting timing for the drive control means to temporarily stop the discharge rollers 48, so that the position of punched holes may be varied in the longitudinal direction of the paper. If the timer adjusts a predetermined period of time by the range from 0 to a given sec, or if the pulse counter adjusts a predetermined pulse count by the range from 0 to a given value, for example, the timing to stop the discharge rollers 48 after the sensor S has detected the trailing portion of the paper P can be adjusted. The timing adjustment may be executed through an operation means such as selection switches provided on the operation board on the main body of the copying apparatus 1. The paper P delivered from the heat fusion device 46 down the arm S1 of the sensor S as a detecting means, as illustrated with dot-and-dash line in Fig. 5, and when the paper P passes through the arm S1, this arm S1 stands up again as illustrated with a solid line in the Fig., to let the sensor S detect the trailing portion of the paper P. Then the sensor S is connected to a jam detection portion (not shown) for detecting paper jam. The jam detection portion checks whether the arm S1 stands up or not when a predetermined time has passed after the paper P delivered from the heat fusion device 46 pushed down the arm S1. If the arm S1 does not stand up, considering it to be a jam, the detection portion stops the electrostatic copying apparatus and gives an indication of jam recovery. The drive control means may comprise; an drive source for driving the discharge rollers 48, which is provided independently of the drive system of the copying apparatus, and a control system for controlling the independent drive source according to a signal from the control system. As shown in Fig. 1, the second paper delivery means 5 is diverged from a switching claw 49 disposed between the delivery rollers 47 and the discharge rollers 48, and is connected to a registration rollers 43 through an intermediate tray 6. The second paper delivery means 5 comprises; the first half portion 5a which diverges from the switching claw 49 and leads the paper P in the intermediate tray 6; a reversing portion 5b which diverges from the switching claw 52 disposed in the midway of the first half portion 5a and which leads the reverced paper P into the intermediate tray 6; the latter half portion 5c covering from a feed repeat rollers 53 to the registration rollers 43. The first half portion 5a includes guide passages 50a, 50b, 50c, delivery rollers 51a, 51b, and a switching claw 52. The reversing portion 5b includes guide passages 50d, 50e, and a delivery rollers 51c. The latter half portion 5c includes a feed repeat rollers 53, delivery rollers 54a, 54b, 54c, and feed passages 55a, 55b, 55c. The delivery rollers 51a of the second paper delivery means is, as described above, driven by the stepping motor G1 of the discharge drive system G. That is, the rotation of the stepping motor G1 is transmitted to the delivery rollers 51a through a timing belt G6, and gears G7, G8, as shown with a broken line in Fig. 5. To execute an image forming process once on the paper P by using an electrostatic copying apparatus of this embodiment, the paper P whereon an image has been formed in the image forming portion 3 is carried by the first delivery portion 4 to be discharged on the copy receiving tray 15. To execute an image forming process on the same paper P for two or more times by using the electrostatic copying apparatus, the switching claw 49 is switched as illustrated with dot-and-dash line in Fig 5, and the paper P whereon the image forming portion 3 has formed image is delivered to the second paper delivery means 5. After staying in the intermediate tray 6 for a time, the paper P is delivered to the image forming portion 3 to form image thereon again. To execute the image forming process on the same side of the paper P for the second time, the paper P with the image formed thereon is carried through the first half portion 5a of the second paper delivery means 5 to the intermediate tray 6, and then the paper P moves through the latter half portion 5c to enter the image forming portion 3 again. At this time, the delivery rollers 51a rotates in the same direction with the other delivery rollers 51b. The image forming process to execute the image forming apparatus on the backside of the same paper P for the second time, the paper whereon the image is formed is delivered into the first half portion 5a of the second paper delivery means 5, where the delivery rollers 51a, 51b of the first half portion 5a are rotated in the opposite direction to carry the paper P from the switching claw 52 to the reversing portion 5b. The paper P turned over is delivered through the reversing portion 5b to the intermediate tray 6, and the paper P is carried through the latter half portion 5c to the image forming portion 3. The punching means 7 is disposed between the switching claw 49 and the discharge rollers 48 in the first paper delivery means 4. As shown in Figs. 5 to 10, the punching means 7 comprises a supporter 71, a pair of punching cutters 72 vertically movable and supported by the supporter 71, coil springs 73 for retaining these punching cutters 72 upward, a punching die 74 for receiving the punching cutters 72, and cams 75 as means for pressing punching cutters 72 downward, thereby to punch holes in the paper P. Of the components, the supporter 71, punching cutters 72, coil springs 73, and punching die 74 are disposed in the upper part of the unit U illustrated with two-dots-and-dash line in Fig. 5, with the switching claw 49, the discharge rollers 48, and the collecting box 76 disposed under the punching die 74 in the first paper delivery means 4. The unit U can be drawn out in the piece from the casing 1 by turning around the shaft U1 and pulling it. As shown in Fig. 2, a pair of cams 75 of the punching means 7 are attached to one rotary shaft 75a disposed in the casing 1, thus being provided in the casing 1. As shown in Figs. 2 to 8, the supporter 71 is composed of channel bar comprising a pair of horizontal side plates 71a, 71b and a vertical side plate 71d. Of the supporter 71, the bottom surface of the lower horizontal side plate 71a also serves as the upper side plate of the guide passage 7a for guiding the paper P. Through holes for inserting the punching cutters 72 are formed in the horizontal side plates 71a, 71b. Bushes 71c with punching cutters 72 inserted are mounted on the surface of the lower horizontal side plate 71a, and the coil springs 73 are fit around these bushes 71c. On the back side of the lower side plate 71a, there are attached paper holders F, which guide the paper P toward the punching die 74 and prevent corners of the paper P from being caught in the through holes in the horizontal side plate 71a. The paper holders F are composed of elastic thin sheet, such as synthetic resin film consisting of polyethylene terephthalate or metal sheet consisting of copper phosphate. As shown in Fig. 11, the paper holders F are disposed near the through holes 74a in the punching die 74. As shown in the Fig., it is preferable that the edges of the paper holders F at least reach the line T shown in the Fig. 11 with dot-and-dash-line, running through the centers of the through holes 74a, and more preferably that the edges of the paper holders F extend over the line T to the downstream side (toward left in this Fig.). If the edges of the paper holders F fail to reach the line T, it is worried that the paper holders F cannot adequately retain the paper P, when the paper P is caught on the punching cutters 72 and go upward along with the cutter. The punching cutter 72 has a cutting edge 72b on its lower end, the upper part of the punching cutter 72 is column form portion contacting with the cam 75, and a flange 72a is formed in the midway portion thereof. The punching cutter 72 is inserted through the through hole in the upper and lower horizontal side plates 71a, 71b of the supporter 71, with vertically movable and having its flange 72a disposed between these horizontal side plates 71a, 71b. Between this flange 72a and the lower horizontal side plate 71a, there is interposed a coil spring 73, which urges the punching cutter 72 upward. The punching die 74 comprises a plate which is formed the through holes 74a, 74b for the punching cutters 72 to enter are formed at positions corresponding to the punching cutters 72 (Figs. 5 to 9 show only one of the punching cutters arranged vertically to the surface of the paper). The punching die 74 also serves as the lower side plate of the guide passage 7a for guiding the paper P. As described above, a pair of cams 75 are attached to one rotary shaft 75a disposed in the casing 1, thus the com 75 is provided in the casing 1. The drive system of the copying apparatus rotates the rotary shaft 75a to run the cams 75, as shown in Figs. 7 to 9, and thus the cams pressure the punching cutters 72 downward so as to punch holes in the paper P. In the punching means 7, when the punching cutter 72 is gone down with rotating of the coms 75 to apply pressure of the cam 75 efficiently downward on the punching cutter 72 as the cam 75 rotates, the axis of the rotary shaft 75a is horizontally shifted by 'α' length to the core line of the punching cutter 72, as shown in Fig. 7. As shown with dot-and-dash line in Figs. 5 to 9 and with solid line in Fig. 10, the pair of cams 75 are attached to the rotary shaft 75a with their phases shifted to each other, so that timing for the punching cutters 72 to punch holes may be staggered and thus load on the rotary shaft 75a or the driving system can be reduced. As shown in Figs. 3 and 10, the third cam 75b is disposed between a pair of cams 75, so as to cope with three punch holes standardized in the United States. To punch the paper P using third hole by using the third cam 75b, the three punching cutter may be provided on the supporter 71. To punch four or more holes in the paper P, a rotary shaft having the same number of cams with the holes may be attached to the casing 1 and a supporter having the same number of punching cutters with the cams may be attached to the unit U. The collecting box 76 is for collecting paper scraps P1 made after the punching cutters 72 punch holes (shown in Fig. 9), and is disposed beneath the through holes in the punching die 74. As shown in Figs. 4 and 5, a window U2 is provided in the front side of the unit U. A transparent plate made of synthetic resin and such is fit in the window U2, thereby to check the amount of paper scraps contained in the collecting box 76. By the way, instead of using the window U2 is not necessary to get a transparent plate, also the window U2 may be composed of a plurality of slits, of a size which will not allow fingers to enter within the machine for safety reasons (around 5mm width 30mm length), as shown in Fig. 6. The window U2 may be disposed in the front side of the casing 1. In this case, there may be provided notches about the same size of the window in each components intervening between the front side of the casing 1 and the collecting box 76. When paper crumbs or the like which are produced by punching are caught in the punching means the punching cutter 72 is locked and paper jam is caused. After that, the lock claws R disposed on the sides of the casing 1 are disengaged from the engaged portions (not shown) as shown in Fig. 2. Then, as shown in the Fig. 2, the unit U is turned and drawn out of the casing 1, and the connection between the cams 75 provided in the casing 1 and the punching cutters 72 disposed in the unit U is released. This sets the punching cutters 72 free and exposes them outside of the casing 1. With the punching cutters 72 pulled up, jam recovery can be easily executed. When the punching means 7 is punching holes, jam occurred in other parts and an electrophotostatic copying apparatus is stoped and the punching cutters 72 are held down by the cams 75 the unit U is turned and drawn out of the casing 1, thereby to release the joint of the cams 75 provided in the casing 1 and the punching cutters 72 disposed in the unit U. This sets the punching cutters 72 free, and jam recovery can be easily executed. For removing paper scraps P1 in the collecting box 76, the collecting box 76 can be taken out with turning and drawing out the unit U from the casing 1. As shown in Figs. 12 and 13, the punching means 7 may be provided with lever L for lifting up the punching cutter 72. The lever L in Fig. 12 has a through hole L1 for the punching cutter 72 to enter at the center thereof, and is mounted on the upper horizontal side plate 71b of the supporter 71 in such a manner as to be turnable on a shaft L2. At the upper end of the punching cutter 72, there is formed a flange 72c to come in contact with the circumference of the through hole L1 of the lever L. Turning the lever L will bring a flange portion 72c into contact with the circumference of the through hole L1, and thus the punching cutter 72 is lifted up. The lever L in Fig. 13 is the same with the lever L in Fig. 12, except for that a shaft L3 is provided on the unit U. As shown in Figs. 14 and 15, there may be also provided a main unit U and a sub unit V, as units drawn out of the casing 1. These units can be separately drawn out of the casing 1. The main unit U is provided with a supporter 71, punching cutters 72, coil springs 73, a punching die 74, a switching claw 49 and the upper rollers 48a of the pair of discharge rollers 48. The unit U can be turned on a shaft U3, and be drawn out in one piece from the casing 1. The sub unit V is provided with a collecting box 76 and the lower roller 48b of the discharge rollers 48. The sub unit V can be turned out in one piece from the casing 1. In treating jam which does not involve the punching means 7, for example, in case jam occurred in parts other than the punching means 7 stops the copying apparatus with the punching cutters 72 not pressed down by the cam 75 while the paper P is caught between the rollers 48a, 48b, the sub unit V is turned and drawn out of the casing 1, as shown in Fig. 15. This releases the contact of the rollers 48a, 48b, and thus the paper P caught between the rollers 48a, 48b can be removed. In removing the paper scraps P1 in the collecting box 76, the sub unit V is turned and drawn out of the casing 1, and thus the collecting box 76 can be drawn out of the sub unit V, as shown with dot-and-dash line in the Fig. In the case of paper jam involving the punching means 7, such as lock-in of the punching cutter 72 due to paper crumbs caught in the unit 7, or stoppage of the copying apparatus with the punching cutters 72 pressed down by the cams 75 due to paper jam occurred in other parts, the sub unit V as well as the main unit U are turned and drawn out of the casing 1. This disconnects the cams 75 and the punching cutters 72, setting the punching cutters 72 free and exposing the cutters outside of the casing 1. With the punching cutters 72 pulled up, jam recovery can be easily executed. In Figs. 17 and 18, there are provided a main unit U and a sub unit V, which can be separately drawn out of the casing 1 in the same manner with the above. The main unit is provided with a supporter 71, punching cutters 72, coil springs 73, a punching die 74, and a switching claw 49. The unit U can be turned around a shaft U3, and be drawn out in one piece from the casing 1. The sub unit V is provided with a pair of discharge rollers 48 and a collecting box 76. The sub unit V can be turned on a shaft V1, and be drawn out in one piece from the casing 1. In treating jam which does not involve the punching means 7, for example, in case jam occurred in parts other than the punching means 7 stops the apparatus with the punching cutters 72 not pressed down by the cams 75 while the paper P is caught between the pair of discharge rollers 48, the sub unit V is turned on a shaft V1 and can be drawn out in one piece from the casing 1. Then the paper P caught between the discharge rollers 48 can be removed. In removing the paper scraps P1 in the collecting box 76, the sub unit V is turned and drawn out of the casing 1, and then the collecting box 76 can be detached from the sub unit V. In the case of paper jam involving the punching means 7, such as lock-in of the punching cutters 72 due to paper crumbs caught in the unit 7, or stoppage of the machine with the punching cutters 72 pressed down by the cams 75 due to paper jam occurred in other parts, the sub unit V as well as the main unit U are turned and drawn out of the casing 1. This disconnects the cams 75 and the punching cutters 72, setting the punching cutters 72 free and exposing the cutters 72 outside of the casing 1. With the puching cutters 72 pulled up, jam recovery can be easily executed. The unit U in Figs. 19 and 20 is provided with a supporter 71, punching cutters 72, coil springs 73, a punching die 74, a collecting box 76 and a discharge rollers 48. The unit U can be turned on a shaft U4 and be drawn out in one piece from the casing 1. As shown with dot-and-dash line in Fig. 20, the collecting box 76 can be detached from the unit U for removing paper scraps P1 therein. The above-mentioned unit U has an advantage that since the switching claw 49 is provided in the casing 1, the unit U is smaller than that in Fig. 1 by the space to be spared for the switching claw 49. In addition, because of being smaller, the unit U is easier to turn. As shown in Figs. 21 to 23, the unit U provided in the electrostatic copying apparatus is movable in the width direction of the paper P. Furthermore, the unit U is provided with an adjustment means A for moving the unit U in the width direction of the paper P so as to adjust the position to punch holes in the paper P. A shaft U1 for turnably supporting the unit U in the casing 1 can slide and be inserted in through holes 16a, 17a which are provided in the side plates 16, 17 of a portion to house the unit U. One side end portion U1a of the shaft U1 is cut off on the circumference in a sectional view. This portion is inserted in a through hole 17a having the same sectional form, thereby to prevent the shaft U1 from rotating while allowing it to move in its core line direction. The unit U is turnably supported by the shaft U1 which is turnably inserted into through holes U6a. The through holes are formed in the side plates U6 constituting the side portions of the unit U. The flanges U1b provided on the shaft U1 comes in contact with the side plates U6, so as not to allow the unit U to slide on the shaft U1. The unit U is turnably supported by the shaft U1, while the unit U is movable in the width direction of the paper P along with the shaft U1 which slides in the core line direction. An adjustment means A for moving the shaft U1 in its core line direction to shift the unit U in the width direction of the paper P includes; a male screw A1 formed at one end portion of the shaft U1; a support metal fitting A2 provided with a through hole A2a and fastened to the side plate 16; and nuts A3, A4 fit on the male screw A1 in such a manner as to hold the support metal fitting A2 between them. In the adjustment means A, unfastening one nut A3, A4 while fastening the other nut A3, A4 moves the shaft U1 to the direction of the unfastened nut A3, A4. As the shaft U1 moves, the unit U shifts, thereby to adjust the position to punch holes in the paper P. Fig. 24 shows another example of the adjustment means A. The adjustment means A includes inclined threads A5 formed on one end portion of the shaft U1, and a worm gear A6 to mesh with the inclined threads A5. The worm gear A6 is turnably supported by the shaft A7 and is fixed in the vertical position. In the adjustment means A, a handle A8 shown with two-dots-and-dash line in the Fig. is attached to the shaft A7. Turning the worm gear A6 with the handle A8 will shift the shaft U1 in its core line direction. Along with the turnig shaft U1, the unit U moves, and thus the opsition to punch holes in the paper P can be adjusted. In addition to the function wherein phase of the cams 75 is varied to stagger timing for the punching cutters 72 to punch holes, there may be suggested another function as shown, for instance, in Figs. 25 to 30. In Fig. 25, one of the punching cutters 72 is made longer than the other and is protruded 'δ' length higher than the other. When a pushing means (not shown) such as a pair of cams 75 of the same phase is brought into contact with the punching cutters 72 as shown with arrows in the Fig. 1 the longer punching cutter 72 comes in contact with the pushing means at first and is pressed downward to punch the first hole in the paper P. Then, the shorter punching cutter 72 comes in contact with the pushing means and is pressed downward so as to punch the other hole in the paper P. When three or more holes are to be punched, a plurality of punching cutters 72 of different lengths may be used. In Fig. 26, a spacer T for providing a time lag in the operation of the punching cutters 72 is provided above the top end of the punching cutters 72. The spacer T has two contact surfaces T1, T2 on the bottom side, which touch the punching cutters 72. These contact surfaces has different hight, one of which is 'γ' higher than the other. The spacer T is supported by a shaft T3 on the side plates U6 of the unit U. When the spacer T is pushed and turned by a puching means (not shown) such as a cam, the punching cutter 72 coming in contact with the contact surface T1 with greater depth is pressed downward to punch the first hole. Then the punching cutter 72 comes in contact with the contact surface T2 having less hight and is pressed downward, thereby to punch the other hole. Since the spacer T needs only one cam 75 as a pushing means, the structure of the pushing means becomes simple. The spacer T has further advantage that because the contact surfaces are large, the position of the punching cutters 72 can be changed as desired, thereby to properly set the interval between the punching cutters 72. In the case of punching three or more holes, contact surfaces of different hight may be provided on the bottom of the spacer T by the number corresponding to the punching cutters 72. Fig. 27 shows an example like in Fig. 26, wherein the spacer T for providing time lag in the operation of the punching cutters 72 is provided above the top end of the punching cutters 72. The spacer T, like the above, is supported by the shaft T3 on the side plates U6 of the unit U. This spacer differs from the above in that the contact surface T touching the punching cutters 72 is of one straight slanting surface, whose hight gradually increases from the side plate U3 of the unit U to the side plate U4. When the pushing means such as a cam 75 (not shown) presses the spacer T to turn it, as shown with an arrow in the Fig., the punching cutter 72 coming in contact with the contact surface at a greater hight is pressed downward to punch the first hole. Then the other punching cutter 72 comes in contact with the contact surface at less hight is pressed down and punches the second hole. The spacer 7 comprises a straight slanting contact surface T4 which comes in contact with the punching cutters 72. Setting a desired number of punching cutters 72 at desired positions can stagger timing for any of the punching cutter 72 to punch holes. Accordingly, the spacer T can advantageously allow it to set the number or the interval of holes as desired. Fig. 28 shows an example, wherein instead of using the spacer T, one side end of a plate I is turnably supported by a shaft I1 disposed on one side plate U6 of the unit U, thereby to stagger timing to punch holes. When the pushing means (not shown) pushes the plate I on the side end opposite to the shaft I1 as shown with an arrow in the Fig., the punching cutter 72 nearer to the shaft I1 is at first pressed down by the plate I and punches the first hole. Then the punching cutter 72 farther from the shaft I1 is pressed down and punches the other hole. Like Fig. 28, the plate I has an advantage that the number or the interval of holes can be set as desired, because turning the plate on the shaft I1 will make the punching cutters 72 punch holes sequentially from the one nearer to the shaft I1. Fig. 29 shows an example which employs a cam 75 having a periphery gently twisted from one side plate U6 to the other side plate U6 of the unit U. When the cam 75 whose periphery is twisted is turned on a turning shaft 75a, the punching cutter 72 coming in contact at first with the periphery is pressed down to punch the first hole. Then the cam 75 turns further and presses down the other punching cutter 72, thereby to punch the other hole. When using the cam 75, the twisted periphery thereof sequentially comes in contact with the punching cutters disposed as desired, thereby to press down the punching cutters 72 one after another. Like Figs. 27 and 28, the cam 75 has an advantage that the number and the interval of holes can be set as desired. Fig. 30 shows an example wherein two solenoids S vertically moves each of the punching cutters 72 separately. A differential control system delays an operation timing for each of the solenoids S, thereby to electrically delay timing to punch holes. Since the compositon provides solenoids S for each punching cutter, the number and the interva of holes can be set as desired. In addition, the differential control system can advantageously vary the delay in the operation timing of each solenoid S as desired. As shown in Figs. 31 and 32, the collecting box 65 for collecting paper scraps P1 (see Fig. 9) made after the punching cutters 72 punch holes, may be turnably supported so that an opening 76a for receiving paper scraps P1 always turns upward. As shown in Figs. 31 to 33, the collecting box 76a comprises a main body 76b with its opening 76b turned upward, support shafts 76c, 76c protruding from the both sides of the main body 76b, and a weight 76d fixed at the bottom of the main body 76b. To allow checking the amount of paper scraps stored within the collecting box 76, the main body 76b is wholly made of transparent synthetic resin material. As shown with two-dots-and-dash line in Figs. 31 and 32, the support shafts 76c, 76c are turnably hooked to metal fittings U7 provided on the side walls of the unit U, thereby to turnably support the collecting box 76. The weight 76d helps position the gravity center of the collecting box 76 near the bottom of the main body 76b, and turns the collecting box 76 keeping balance to turning of the unit U, so as to turn the opening 76a of the collecting box 76 upward. For detaching the collecting box 76 from the unit U, as shown with an arrow in Fig. 32, an opening U7a to let the support shaft 76c pass through is provided in the metal fitting U7, which turnably supports the support shaft 76c. When the unit U is turned for the purpose of jam recovery or removal of paper scraps P1, the main body 76b of the collecting box 76 turns on the support shaft 76c keeping balance to the movement of the unit U, thereby to maintain the opening 76a always turned upward. Thus paper scraps P1 is prevented from falling off from the collecting box 76. As the function to prevent paper scraps P1 from falling off from the collecting box 76, a plate spring B as an elastic member B shown in Figs. 34 and 35 may be used so as to lift up the opening 76a side of the collecting box 76. In the Fig., the collecting box 76 is housed in a retaining portion U11 surrounded with a front-side plate U8, bottom plate U9 and back-side plate U10 of the unit U. The plate spring B is disposed between the front-side plate U8 and the collecting box 76 in the retaining portion U11. The side of the back-side plate U10 which is on the collecting box bottom 76e side is disposed close to the bottom of the collecting box 76, so that the bottom side 76e of the collecting box 76 is not also lifted up when the plate spring lifts up the opening side 76a of the collecting box 76. Not to hinger the opening 76a side from being lifted up, this back-side plate U10 is slanted, going farther from the collecting box 76 on the opening side 76a. As shown in Fig 34, the casing 1 is provided with a pressure projection E as a pressurinzing member. This projection E pressures the collecting box 76 toward the front-side plate U8 against the elastic stress of the plate spring B, while the unit U is pressed within the casing 1. The opening 76a of the collecting box 76 is pressured toward the front-side plate U8 by the pressure projection E, and thus corresponds with the through hole 74a in the punching die 74 of the punching means 7, thereby to collect paper scraps P1. The pressure projection E comprises a metal plate having a sponge affixed to the surface touching the collecting box 76, so as to prevent damage on the surface of the collecting box 76. When the unit U is turned and drawn out of the casing 1, as shown in Figs. 35 and 36, the collecting box 76 is not pressured by the pressure projection E. Hence, the collecting box 76 is raised up by the elastic stress of the plate spring B and its opening 76a is turned upward. Therefore, the paper scraps P1 is prevented from falling off from the opening 76a. In the electrostatic copying apparatus in the Fig., an added data printing device D is provided between the delivery rollers 47 of the first paper delivery portion 4 and the punching means 7. The added data printing device D comprises; a platen roller D1 for supporting the paper P from below; a thermal head D2 which can ascent and descent in the direction of the platen roller D1; and reels D3, D4 for feeding thermal ribon to the thermal head D2. The added data printing device D is used to print added data such as page number or date at a predetermined position on the paper P whereon an image has been formed. It is understood that the structure of an image forming apparatus according to the present invention should not be limited to the above embodiments. For example, the embodiment in the Fig. uses the sensor S disposed in the paper delivery portion 4 as a detecting means. As the detecting means, there can be provided such a means as to judge the length of the paper P from previously inputted paper size data such as the kind of paper cassette 13a, 13b to feed the paper P and the like, and to execute an arithmetic processing to calculate and detect the position of the trailing portion of the paper P, namely, the distance from the trailing edge of the paper P to the punching means 7. The detecting means is incorporated into a drive control means for controling the operations of the electrostatic copying apparatus. The data of the distance from the trailing portion of the paper P to the punching means 7, which is detected by the detecting means, is inputted as data of a predetermined pulse count or data of a predetermined period of time for setting timing to temporarily halt the paper P. The data is used when the drive control means controls the discharge rollers 48. The drive control means may be to detect the leading edge of the paper P, to control the rotating of the discharge rollers 48 according to the relationship between the signal and the length of the paper P, and to stop temporarily the paper P with fasing trailing egde thereof on the punching means. In the above-mentioned embodiments, the unit U is turned around the turning shaft and is drawn out of the casing 1. The unit U may be moved parallel on rails and is drawn out of the casing 1. Each embodiment uses the discharge rollers 48 as a discharge means. However, the discharge means may be composed of belt. In each embodiment, the upper and the lower guide plates composing the guide passage 7a of the paper P are also used as the supporter 71 of the punching cutter 72 and as the punching die 74 respectively. These upper and lower guide plates may be used separately from these members. The function to turn the collecting box 76 keeping balance to turning of the unit may not necessarily comprise the support shafts 76c and the weight 76d. For example, there may be adopted a function wherein turning of the unit in the casing 1 is trnsmitted through a gear or belt to the support shaft of the collecting box 76, thereby to mechanically turn the collecting box 76. The arrangement of a discharge roller 48, punching means 7, collecting box 75 and the like may be properly altered in the unit U. The punching means 7 may be disposed in other casing which is externally attached to the casing 1 which houses the optical system 2, image forming portion 3, the first and second paper delivery portions 4, 5, intermediate tray and such. The embodiments in the Figs. show an electrostatic copying apparatus as an example of an image forming apparatus. The configuration according to the present invention may be applied to other image forming apparatus such as a laser beam printer.

Claims: An image forming apparatus comprising: paper delivery means (4) for carrying paper sheets (P) out of the apparatus after an image has been formed on the paper; detecting means (S) for detecting an edge of a paper (P) with respect to the paper delivery direction as the paper (P) is delivered by the paper delivery means (4); punching means (7) for punching holes in the paper (P), being disposed adjacent to discharge means (48) located in the paper delivery means; and drive control means (C) responsive to the detecting means (S) for controlling the discharge means (48) to halt the discharge means (48) with a predetermined portion of the paper (P) at the punching means (7) and to restart the discharge means (48) after the punching means (7) has punched the holes so that the paper (P) with holes punched therein is discharged, characterized in that the detecting means (S) is adapted to detect the leading or the trailing edge of the paper with respect to the paper delivery direction and the drive control means (C) is adapted to control the discharge means (48) and the punching means (7) to punch holes in the paper (P) adjacent the trailing edge thereof with respect to the paper delivery direction, the drive control means (C) including a timer responsive to a signal from the detecting means (S) for halting the discharge means (48) after a predetermined time period, the timer having an adjustment function for adjusting the predetermined time period through an operation means such as selection switches provided on the operation board of an image forming apparatus, thereby altering the position of the punched holes with respect to the trailing edge of the paper (P). An image forming apparatus according to claim 1, wherein said discharge means (48) comprises a pair of discharge rollers (48a, 48b). An image forming apparatus according to claim 1, wherein the drive control means (C) controls a drive system (G) of the discharge means (48), the drive system being provided separately from a drive system of said image forming apparatus. An image forming apparatus according to claim 1, wherein said drive control means (C) includes; an electromagnetic clutch (K) disposed between the drive system of said image forming apparatus and discharge means (48); and a control system (C) for switching the electromagnetic clutch according to the signal from said detecting means. An image forming apparatus according to claim 1, wherein the drive control means (C) includes a pulse counter which converts the rotation of a rotation member of the paper delivery means (4) including discharge means (48) into pulses thereby to count the rotation thereof and which outputs a signal upon counting a predetermined pulse count so as to set timing to stop discharge means (48) after receiving the signal from detecting means (S). An image forming apparatus according to claim 5, wherein the pulse counter has said adjustment function, which is to adjust the predetermined pulse count for adjusting timing to stop the discharge means (48) after receiving the signal from said detecting means (S) and altering said position of the punch holes. An image forming apparatus according to claim 1, wherein detecting means includes a sensor (S) provided with a detecting arm (S1), which falls down on touching the leading edge of paper carried by the paper delivery means (4) and which stands up when the trailing portion of the paper passes. An image forming apparatus according to claim 7, further provided with a jam detecting function which determines a paper jam if the detecting arm (S1) does not stand up when a predetermined period of time has passed after the detecting arm (S1) has fallen down. An image forming apparatus according to claim 1, wherein; the punching means (7) includes a plurality of punching cutters (72) disposed at a predetermined interval in the width direction of the paper (P) carried by the paper delivery means (4), a punching die (74) for receiving the punching cutters (72), and pushing means (7) to project the punching cutters (72) toward the punching die (74), wherein the pushing means (7) is supported in a casing (1) covering the punching means (7), and the punching cutters (72) and the punching die (74) are provided in a unit (U) which is able to be drawn out of the said casing (1). An image forming apparatus according to claim 9, wherein; the unit (U) is adapted to be detached from the casing by turning the unit (U); and under the punching die (74) in this unit (U), there are provided a collecting box (76) to receive through an opening (76a) thereof paper scraps (P1) made by punching holes and to store the paper scraps (P1) therein, and means for always turning the opening (76a) of said collecting box (76) upward when the unit (U) is turned. An image forming apparatus according to claim 1, wherein; the punching means (7) for punching plural holes in paper (P) carried by said paper delivery means (4) includes a plurality of punching cutters (72) disposed at a predetermined interval in the width direction of the paper (P) and a punching die (74) for receiving these punching cutters (72) and timing for the plural punching cutters (72) to punch holes is shifted for each punching cutter (72). An image forming apparatus according to claim 1, wherein; the punching means (7) includes a plurality of punching cutters (72) disposed at a predetermined interval in the width direction of paper (P) carried with the paper delivery means (4) and a punching die (74) for receiving the punching cutters (72), whereby at least the punching cutters (72) and the punching die (74) are able to be drawn out of a casing (1) which covers said punching means (7) and are disposed on a unit (U) movable in the width direction of the paper (P); and the apparatus includes adjustment means (A) for moving the unit (1) in the width direction of the paper (P) thereby to adjust a position for said punching means (7) to punch holes in the paper (P). An image forming apparatus according to claim 9, wherein the pushing means (7) is a cam (75) turning on a rotary shaft (75a). An image forming apparatus according to claim 13, wherein; the punching cutter (72) is a rod whose axis is directed in the pushing direction of the pushing means (7), and the axis of the rotary shaft (75a) of the cam (75) drifts from the axis of the punching cutters in the direction to carry a paper. An image forming apparatus according to claim 9, wherein; said punching means (7) includes a supporter (71) for supporting the punching cutters (72); the supporter (71) includes a lower horizontal plate (71a) also serving as one of the guide plates of a guide passage (7a) to guide paper (P), and an upper horizontal plate (71b) disposed above said lower horizontal plate (71a); and the punching cutter (72) is provided with a flange (72a) which comes in contact with the bottom side of said upper horizontal plate (71b), so as to stop rising of the punching cutter (72) with the edge thereof positioned slightly above the bottom side of the lower horizontal plate (71a). An image forming apparatus according to claim 15, wherein a punching die (74) also serves as the other guide plate of the guide passage (7a) for guiding paper. An image forming apparatus according to claim 9, wherein the unit (U) is provided with discharge means (48) for discharging paper (P). An image forming apparatus according to claim 17, wherein there is provided under the punching die (74) in the unit (U), a collecting box (76) which receives through an opening (76a) thereof paper scraps (P1) made by punching holes and stores the paper scraps (P1) therein. An image forming apparatus according to claim 18, wherein; the unit is provided with a main unit (U) and a sub unit (V) which can be drawn out separately from the casing (1); the main unit (U) is provided with the punching cutters (72), the punching die (74), and one of a pair of discharge rollers (48a) comprising said discharge means (48); the sub unit (V) is provided with the collecting box (76), and the other discharge roller (48b) of said discharge means (48). An image forming apparatus according to claim 18, wherein; the unit is provided with a main unit (U) and a sub unit (V) which can be drawn out separately from a casing (1); the main unit (U) is provided with punching cutters (72) and the punching die (74); and the sub unit (V) is provided with the collecting box (76) and said discharge means (48). An image forming apparatus according to claim 9, wherein; the unit (U) is able to be drawn out of the casing (1) and to move in the width direction of a copying paper (P); and the unit (U) is provided with adjustment means (A) for moving the unit in the width direction of the paper thereby to adjust a position for the punching means (7) to punch holes in the paper (P). An image forming apparatus according to claim 21, wherein; the unit may be turned on a shaft (U1) movable along with the unit in the width direction of the paper (P), and thus can be drawn out of a casing (1); and the adjustment means (A) can move the shaft (U1) in the width direction of the paper (P), thereby to move the unit (U) in the width direction of the paper (P). An image forming apparatus according to claim 9, wherein there is provided under the punching die (74) in the unit (U), a collecting box (76) which receives through an opening (76a) thereof paper scraps (P1) made by punching holes and stores the paper scraps (P1) therein. An image forming apparatus according to claim 23, wherein; the unit (U) can be drawn out with turning from the casing (1); and the unit (U) is provided with means for always turning the opening of the collecting box (76) upward when the unit (U) is turned. An image forming apparatus according to claim 24, wherein; the collecting box (76) is turnably supported in the unit (U); and means for always turning the opening of the collecting box (76) upward when the unit (U) is turned, also serves as the turning means for turning the collecting box (76). An image forming apparatus according to claim 24, wherein; the means for always turning the opening of the collecting box (76) upward when the unit (U) turns is an elastic member (B) which lifts up the opening side of the collecting box (76) when the unit (U) is turned; and the casing (1) is provided with a pressurizing member (E) which pressures the collecting box (76) against the elastic stress of the elastic member (B) when the unit is pressed in the casing (1), thereby to set the opening of the collecting box (76) beneath the punching die (74). An image forming apparatus according to claim 9, wherein the punching means (7) is provided with levers (L) to lift up punching cutters (72). An image forming apparatus according to claim 9, wherein the punching means (7) is adapted to delay timing to punch holes for each of plural punching cutters (72). An image forming apparatus according to claim 9, wherein said paper delivery means (4) is provided with paper holders (F) which are made of a thin elastic plate, and whose leading edges are elastically pressured on the punching die (74) so as to guide paper to the punching die (74).

Inventors: HAYASHI KIYOSHI, ITO YUKIHIRO, KONDO TAKASHI, MIYAKE TAKASHI, MIYOSHI YOSHITAKE, OKAUCHI YOSHIFUMI, OURA JUNICHI, SHIGEMURA YUTAKA, UMEZAWA HIDEO, YANO SATOSHI, YOSHIMOTO MITSUHARU, HAYASHI, KIYOSHI, ITO, YUKIHIRO, KONDO, TAKASHI, MIYAKE, TAKASHI, MIYOSHI, YOSHITAKE, OKAUCHI, YOSHIFUMI, OURA, JUNICHI, SHIGEMURA, YUTAKA, UMEZAWA, HIDEO, YANO, SATOSHI, YOSHIMOTO, MITSUHARU
Applicants: MITA INDUSTRIAL CO LTD, MITA INDUSTRIAL CO. LTD.
Application year: 1990
Main classification: G03G15
IPC codes: B26D7, B26F1, G03G15