Electrostatic copying apparatus capable of copying on both surfaces

Abstract: An electrostatic copying apparatus capable of both-­ surface copying comprises a main copying system and a document sending device for conveying a document to be copied through an exposure area, said main copying system including copying paper conveying means defining a copying paper conveying passage, image forming means for forming an image on copying paper conveyed through the paper conveying passage, copying paper returning means defining a copying paper returning passage for returning copying paper having the image formed on one surface and paper re-feed means for receiving the copying paper re­ turned through the paper returning passage and feeding it again to the paper conveying passage. According to a first aspect, improvement is made in the paper re-feed means, and according to a second aspect, document feed means in the document sending device is improved. There is also provided a sheet material feeding device which can be conveniently applied to the paper re-feed means or the document feed means. The sheet material feeding device comprises a first feed means for feeding sheet materials in the stacked state from the uppermost one and a second feed means for feeding the sheet materials from the lowermost one.

Description: FIELD OF THE INVENTION This invention relates to a device for feeding sheet materials according to the preamble of claim 1. DESCRIPTION OF THE PRIOR ART In recent years, an electrostatic copying apparatus capable of copying documents on both surfaces of copying papers has been proposed and come into practical application in order to save copying papers and decrease the number of documents to be preserved. Such a type of electrostatic apparatus generally comprises copying paper conveying means defining a paper conveying passage, image-forming means for forming an image on copying paper conveyed through the paper conveying passage, copying paper returning means defining a paper returning passage for returning copying paper having an image formed on its one surface, and copying paper re-feed means for receiving the copying paper returned through the paper returning passage and re-feeding it to the paper conveying passage. On the other hand, an electrostatic copying apparatus equipped further with a device for sending documents to be copied through an exposure zone has also been widely used in order to simplify the copying operation. The document sending device is comprised of a document receiving stand, document feed means for feeding documents on the document receiving stand, and document conveying means for conveying the documents through the exposure zone. The conventional electrostatic copying apparatus capable of forming a copied image on both surfaces of copying paper which is provided with the document sending device has some problems which are desired to be solved. Primary problems exist with regard to the mode of conveying the document in the document sending device and to the mode of conveying the copying paper in a main copying system in the copying apparatus. In particular, when both surfaces of a document are to be copied on both surfaces of copying paper, it is necessary to arrange the copied documents or the copies in proper sequence after the end of the both-surface copying, and this sequencing operation is troublesome. Furthermore, when both surfaces or a document are to be copied on both surfaces of copying paper, the operation of placing documents to be copied on the document receiving stand is relatively troublesome. Moreover, in the event of paper jamming particularly when both surfaces of a document are to be copied on both surfaces of copying paper, comparatively many copying papers will be wasted, and the documents or the copies must be sequenced after the copying operation. The said troubles also apply to the photocopying device of the JP-A-6061767, in which documents are manually returned to the original placing plate for double-sided copying. SUMMARY OF THE INVENTION It is a main object of this invention to provide an accurately working sheet material device which can be conveniently applied to an electrostatic copying apparatus capable of copying both surfaces in which even in the case of copying on both surfaces, the documents and the copies are properly sequenced at the end of copying and no operation of sequencing is necessary, whereby also wasting of copying papers in the event of paper jamming can be reduced. This object will be achieved by the features of claim 1, wherein other objects of the present invention along with its features will become apparent from the following description. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a sectional view showing in a simplified form a first embodiment of the electrostatic copying apparatus capable of copying on both surfaces of copying paper constructed in accordance with this invention; Figure 2 is a sectional view showing part of paper re-feed means in the electrostatic copying apparatus of Figure 1 on an enlarged scale; Figures 3-A and 3-B are sectional views showing the paper re-feed means in a first feed condition and a second feed condition, respectively; and Figure 4 is a perspective view showing in a simplified form overlapping feed preventing means and a driving system therefore in the paper re-feed means of Figure 2. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT The invention will be described in detail with reference to the accompanying drawings. Figure 1 shows in a simplified form an embodiment of an electrostatic copying apparatus to which a sheet material feeding device in accordance with this invention can be applied. In Figure 1, the illustrated electrostatic copying apparatus includes a main copying system 2 and a document sending device shown generally at 3 and disposed on the upper surface of the main copying system 2. Outline of the Main Copying System of the Copying Apparatus in this Embodiment With reference to Figure 1, the main copying system 2 has a parallelepipedal housing 4. A transparent plate 6 on which to place a document to be copied is disposed on the upper surface of the housing 4. A rotating drum 8 constituting image-bearing means is disposed rotatably in the nearly central part of the housing 4. A photosensitive material is disposed on at least a part of the peripheral surface (on the entire peripheral surface in the illustrated embodiment) of the rotating drum 8. Around the rotating drum 8 to be rotated in the direction shown by an arrow 10 are disposed a charging zone 12, an exposure zone 14, a developing zone 16, a transfer zone 18, a peeling zone 20 and a cleaning one 22 in this sequence as viewed in the rotating direction of the rotating drum 8. A charging corona discharge device 24 is provided in the charging zone 12. A developing device 26 is provided in the developing zone 16. A transfer corona discharge device 28 is provided in the transfer zone 18, and a peeling corona discharge device 30, in the peeling zone 20. A cleaning device 32 is provided in the cleaning zone 22. The illustrated developing device 26 is equipped with a development receptacle 34 for holding a developer composed of toner particles and carrier particles. A magnetic brush mechanism 36 is disposed at that site within the development receptacle 34 which is opposite to the rotating drum 8. An agitating mechanism 38 for agitating the developer is also disposed within the development receptacle 34. An opening is formed in the upper surface of the development receptacle 34 and a toner particle holding vessel 40 is mounted on the opening portion. The toner particle holding vessel 40 is opened at its upper surface and a closure 42 is mounted on the opening portion of the upper surface for free opening and closing. A discharge opening is formed in the bottom wall of the toner particle holding vessel 40, and a toner particle feed roller 44 is rotatably mounted on the discharge opening. Hence, fresh toner particles are supplied to the toner particle holding vessel 40 by opening the closure 42. The toner particles held in the vessel 40 are fed to the development receptacle 34 through the discharge opening by the rotation of the toner particle feed roller 44. The developer in the development receptacle 34 is held by the magnetic brush mechanism 36 and is brought into contact with the peripheral surface of the rotating drum 8 in the developing zone 16. The illustrated cleaning device has a cleaning blade 46 acting on the surface of the photosensitive material on the rotating drum 8. Copying paper conveying means shown generally at 48 is also disposed within the housing 4. Copying paper feed means is provided at one end portion (the right end portion in Figure 1) of the paper conveying means 48. In the illustrated embodiment, the paper feed means is comprised of a first copying paper feed device 50a and a second copying paper feed device 50b of the cassette type. The first paper feed device 50a is constructed of a cassette receiving section with a feed roller 52 and a copying paper cassette 54 to be detachably loaded into the cassette receiving section through an opening formed in the right wall of the housing 4. By the action of the feed roller 52, copying paper sheets are fed one by one from a stacked paper layer (not shown) held in the cassette 54. The copying paper fed from the cassette 54 is sent to a pair of conveyor rollers 60 and 62 after advancing between guide plates 56 and 58. The second paper feed device 50b disposed above the first paper feed device 50a is comprised of a combination of a cassette receiving section with a feed roller 64 and a copying paper cassette 66 to be detachably loaded into the cassette receiving section through the opening formed in the right wall of the housing 4. By the action of the feed roller 64, paper sheets are fed one by one from a stacked layer of paper sheet (not shown) held in the cassette 66. The copying paper fed from the cassette 66 is sent to the pair of conveyor rollers 60 and 62 through the space between the guide plate 58 and guide plate 70. In the illustrated embodiments, copying paper sheets having a JIS A3 size, for example, are held in the paper cassette 54, and copying paper sheets of a JIS A4 size, for example, in the paper cassette 66. The illustrated copying paper conveying means 48 includes the pair of conveyor rollers 60 and 62, a pair of conveyor rollers 90 and 92, a conveyor belt mechanism 94, an upper roller 98 and a lower roller 100 in a fixing device 96, a pair of switching conveyor rollers 102 and 104, and a pair of discharge rollers 106 and 108. These elements define a paper conveying passage extending in the left-right direction in Figure 1. Hence, the copying paper fed to the conveyor rollers 60 and 62 from the paper feed means (the first paper feed device 50a or the second paper feed device 50b) is conveyed to the pair of conveyor rollers 90 and 92 past the guide plate 110 by the action of the pair of conveyor rollers 60 and 62. Between the guide plates 112 and 114, it is conveyed to the transfer zone 18 and the peeling zone 20 by the action of the pair of conveyor rollers 90 and 92. Then, the copying paper is conveyed by the action of the conveyor belt mechanism 94 and fed to the upper roller 98 having a heater 116 disposed therein and the lower roller 100 kept in press contact with the upper roller 98. It will be seen from Figure 1 that the illustrated electrostatic copying apparatus permits both-surface copying and one-surface overlapping copying. In relation to this, therefore, the apparatus includes copying paper returning means 118 defining a copying paper returning passage, and downstream of the paper returning means 118 is disposed a copying paper re-feed means 119 (to be described in detail hereinafter) to which a sheet material feed device in accordance with this invention is applied. The illustrated paper returning means 118 is provided with a pair of conveyor rollers 120 and 122 and a pair of conveyor rollers 124 and 126, and further includes a first conveying direction switching means disposed between the upper roller 98 and the lower roller 100 and the pair of switching conveyor rollers 102 and 104, a second conveying direction switching means disposed between the pair of switching conveying rollers 102 and 104 and the pair of discharge rollers 106 and 108, and a holding section for switching the conveying direction disposed below the second conveying direction switching means. The first conveying direction switching means is equipped with a switching guide member 134 which is adapted to be selectively held at a first position shown by a solid line in Figure 1, a second position shown by a two-dot chain line 134A and a third position shown by a two-dot chain line 134B. The switching guide member 134 is held at the first position when it conducts the copying paper toward the pair of switching conveyor rollers 102 and 104 from the upper roller 98 and the lower roller 100; at the second position when it conducts the copying paper toward the conveyor rollers 120 and 122 from the upper roller 98 and the lower roller 100; and at the third position, when it conducts the copying paper toward the pair of conveyor rollers 120 and 122 from the conveying direction switching holding section by the action of the pair of switching conveyor rollers 102 and 104. The second conveying direction switching means is provided with a switching guide member 136 adapted to be selectively held at a first position shown by a two-dot chain line 136A in Figure 1 and a second position shown by a solid line. The switching guide member 136 is held at the first position when it conducts the copying paper toward the pair of discharge rollers 106 and 108 from the pair of switching conveying rollers 102 and 104, and at the second position, when it conducts the copying paper to the conveying direction switching holding section from the upper roller 98 and the lower roller 100 by the action of the pair of switching conveyor rollers 102 and 104, or it conducts the copying paper toward the pair of conveyor rollers 120 and 122 from the switching holding section by the action of the pair of switching conveying rollers 102 and 104. The aforesaid positioning of the switching guide members 134 and 136 is achieved by an actuator such as a rotary solenoid. The conveying direction switching holding section is comprised of a pair of spaced guide holding plates 138 and 140, and in relation to the foregoing description, the switching conveyor rollers 102 and 104 can be rotated in a normal and a reverse direction. An oscillating guide member 147 free to oscillate between a first position shown by a solid line and a second position shown by a two-dot chain line 147 is disposed between the pair of conveyor rollers 120 and 122 and the pair of conveyor rollers 124 and 126. The oscillating guide member 147 is held at the first position when the size of copying paper is relatively small, and at the second position when the paper size is relatively large. The paper re-feed means 119 is provided with a copying paper receiving stand 150. The paper receiving stand 150 extends from left to right in Figure 1 below the paper conveying passage, and at its front end position is provided an overlapping feed preventing means 133 comprised of a pair of a first upper roller 130 and a second lover roller 132. A copying paper re-feed passage for conducting the copying paper fed from the paper re-feed means 119 in the manner to be described hereinafter toward the paper conveying passage is disposed downstream of the paper re-feed means 119. In the illustrated embodiment, the paper re-feed passage is defined by a pair of guide plates 151 and 152. On the other hand, in the upper portion of the housing 4, an optical device shown generally at 153 is provided for scanning and exposing a document on the transparent plate 6 and projecting the image of the document onto a photosensitive material on the rotating drum 8 in the exposure zone 14. The optical device 153 has a document illuminating lamp 154 for illuminating the document placed on the transparent plate 6, and a first reflecting mirror 155, a second reflecting mirror 156, a third reflecting mirror 157, a lens assembly 158 and a fourth reflecting mirror 159 for projecting the reflected light from the document onto the photosensitive material. During scanning exposure, the document illuminating lamp 154 and the first reflecting mirror 155 are moved at a velocity V from a start-of-scan position shown by a solid line to a given position (for example, a maximum end-of-scan position shown by a two-dot chain line) substantially horizontally, and the second reflecting mirror 156 and the third reflecting mirror 157, at a velocity (½V) half of the moving velocity V from a start-of-scan position shown by a solid line to a given position (for example, a maximum end-of-scan position shown by a two-dot chain line). At this time, the reflected light from the document illuminated by the document illuminating lamp 154 is reflected successively by the first, second and third reflecting mirrors 155, 156 and 157 and reaches the lens assembly 158. It is then reflected by the fourth reflecting mirror 159, and reaches the photosensitive material in the exposure zone 14. When the scanning exposure is over, the document illuminating lamp 154, the first reflecting mirror 155, the second reflecting mirror 156 and the third reflecting mirror 157 are returned to the start-of-scan position shown by a solid line. The operation of the main body of the copying apparatus described above and shown in the drawings will be generally described below. The rotating drum 8 is rotated in the direction of arrow 10. During the rotation of the rotating drum 8, the charging corona discharge device 24 substantially uniformly charges the photosensitive material to a specific polarity in the charging zone 12. Then, in the exposure zone 14, the optical device 153 projects the image of the document to form a latent electrostatic image corresponding to the document on the photosensitive material. Thereafter in the developing zone 16, the developing device 26 applies a toner to the electrostatic latent image on the photosensitive material to develop the latent electrostatic image to a toner image. In the transfer zone 18, the copying paper fed from the paper feed means as described above (the conveying of the paper will be further described hereinafter) is brought into contact with the photosensitive material, and by the action of the transferring corona discharge device 28, the toner image on the photosensitive material is transferred to the copying paper. Then, in the peeling zone 20, the copying paper is peeled from the photosensitive material by the action of the peeling corona discharge device 30. After peeling, the rotating drum 8 continues to rotate, and in the cleaning zone 22, the toner particles remaining on the photosensitive material after transfer are removed by the action of the cleaning blade 46 of the cleaning device 32. In the meantime, the copying paper having the toner image transferred thereto is conveyed to the fixing device 96 where the toner image is fixed under heat. Now, the conveying of copying paper will be described. In the case of forming an image only on one surface of copying paper, the switching guide members 134 and 136 are held at the first position. The copying paper introduced into the paper conveying passage from the paper feed means (the first paper feed device 50a or the second paper feed device 50b) is conveyed through the paper conveying passage, and during this time, the toner image is tranferred to one surface (the upper surface) of the copying paper. The toner image is fixed to one surface of the paper by the action of the upper roller 98 and the lower roller 100 of the fixing device 96. Then, the paper having an image formed on one surface thereof is fed to the pair of switching conveyor rollers 102 and 104 after passing over the upper surface of the switching guide member 134 held at the first position. It is then conveyed to the pair of discharge rollers 106 and 108 after passing over the switching guide member 136 by the action of the pair of switching conveyor rollers 102 and 104 which are rotating in a normal direction (the direction in which the paper is conveyed downstream), and discharged onto the receiving tray 142 through an opening formed in the left wall of the housing 4 by the action of the pair of discharge rollers 106 and 108. As a result, a copy having the image formed on its one surface is obtained. In the case of forming an image overlappingly on one surface of the copying paper, the switching guide member 134 is held at the second position and the switching guide member 136, at the first position. The copying paper introduced into the paper conveying passage from the paper feed means is conveyed through the paper conveying passage. During this conveyance, an image is formed on one surface of the paper in the manner described hereinabove. The copying paper having the image formed on one surface is then guided by the right side edge of the switching guide member 134 held at the second position, introduced into the paper returning passage, and through the paper returning passage, received properly by the paper receiving stand 150 of the paper re-feed means 119. When the copying paper conveyed at this time is of a relatively small size, the paper fed to the pair of conveyor rollers 120 and 122 is conveyed to the pair of conveyor rollers 124 and 126 via a space between the guide plate 148 and the oscillating guide member 147 at the first position by the action of the pair of conveyor rollers 120 and 122, and further by the action of the conveyor rollers 124 and 126, is received in the paper re-feed means 119. On the other hand, if the copying paper is of a relatively large size, the paper fed to the pair of conveyor rollers 120 and 122 is guided to the under surface of the oscillating guide member 147 at the second position by the action of the pair of conveyor rollers 120 and 122 and directly received by the paper re-feed means 119. When a required number of copying paper sheets have been received in the paper re-feed means 119, the switching guide member 134 is held at the first position. Thereafter, the copying papers are delivered to the paper re-feed passage from the paper re-feed means 119 in the manner to be described hereinafter. The delivered copying paper sheets are fed to the paper conveying passage one by one via the paper re-feed passage. During re-conveying through the paper conveying passage, a toner image is transferred overlappingly on the aforesaid one surface of the copying paper in the transfer zone 18. By the action of the fixing device 96, the toner image is fixed to the paper to form the image overlappingly on one surface of the paper. The copying paper is then guided by the upper surfaces of the switching guide members 134 and 136 at the first position, and discharged onto the receiving tray 142 in the same way as in the case of one-surface copying. As a result, a copy having images overlappingly on one surface thereof is obtained. In the case of forming an image on both surfaces of copying paper, the switching guide member 134 is held at the first position and the switching guide member 136 is held at the second position. The copying paper introduced into the paper conveying passage from the paper feed means is conveyed through the paper conveying passage, and during this conveyance, an image is formed on one surface of the paper in the same way as described above. The copying paper having the image formed on its one surface is then fed to the pair of switching conveyor rollers 102 and 104 via the upper surface of the switching guide member 134 held at the first position, and by the action of the switching conveyor rollers 102 and 104 rotating in the normal direction, is guided by the lower undersurface of the switching guide member 136 held at the second position and introduced into between the guide holding plates 138 and 140. When the trailing end of the copying paper conveyed as described above goes past the switching guide member 134 (at which time the trailing end portion of the copying paper is nipped between the pair of switching conveyor rollers 102 and 104), the switching guide member 134 is held at the third position and the switching conveyor rollers 102 and 104 are rotated in an opposite direction (the direction in which the paper is conveyed upstream). The copying paper conducted between the guide holding plates 138 and 140 is guided to the left side edge of the switching guide member 134 from its rear end side by the action of the switching conveyor rollers 102 and 104 rotating in the opposite direction, and introduced into the paper returning passage. Through the paper returning passage, it is received properly in the paper receiving stand 150 of the paper re-feed means 119. As in the case of one surface overlapping copying, if the size of the paper is relatively small, the paper fed to the pair of conveyor rollers 120 and 122 advances between the oscillating guide member 147 and the guide plate 148 and by the action of the pair of conveyor rollers 124 and 126, is received by the paper re-feed means 119. On the other hand, when the paper size is relatively large, the copying paper fed to the conveyor rollers 120 and 122 is guided by the under surface of the oscillating guide member 147 and received directly by the paper re-feed means 119. When a required number of copying paper sheets have been received by the paper re-feed means 119 as described above, the switching guide members 134 and 136 are held at the first position. Thereafter, the copying paper sheets are delivered to the paper re-feed passage from the paper re-feed means 119 in the manner to be described. The delivered copying papers are fed one by one to the paper conveying passage via the paper re-feed passage, and during re-conveying through the paper conveying passage, a toner image is transferred to the other surface of the copying paper (that surface which is opposite to the image-bearing surface) in the transfer zone 18. The toner image is then fixed to the other surface of the copying paper by the action of the fixing device 96. Thus, images are formed on both surfaces of the copying paper. Then, as in the case of one-surface copying, the copying paper is guided by the upper surfaces of the switching guide members 134 and 136 held at the first position, and discharged onto the receiving tray 142. As a result, a copy having images formed on both surfaces is obtained. Copying paper re-feed means in the above described embodiment Now, with reference to Figures 1 and 2, the copying paper re-feed means 119 will be described. The illustrated copying paper re-feed means 119 includes the paper receiving stand 150, the overlapping feed preventing means 133, a first feed means 160 disposed above the paper receiving stand 150, and a second feed means 162 disposed below the paper receiving stand 150. The paper receiving stand 150 is constructed of a plate-like member, and permits receipt of copying papers returned through the paper returning passage, in a stacked state on its surface. Stop means 164 is annexed to the front end portion of the paper receiving stand 150. The illustrated stop means 164 is comprised of a hampering piece 168 secured to a supporting shaft 166 mounted rotatably. The hampering piece 168 is selectively held at an operative position shown by a solid line in Figure 1 and also in Figure 2 and non-operative position shown by a two-dot chain line in Figure 1 and also in Figures 3-A and 3-B by an actuator (not shown) such as an electromagnetic solenoid. At the operative position, the hampering piece 168 projects upwardly substantially perpendicularly from the upper surface of the paper receiving stand 150 (an opening 170 is formed in the paper receiving stand 150 so that the hampering piece 168 can project upwardly), and makes contact with the leading end of the copying paper moving over the paper receiving stand 150 to hamper the movement of the copying paper accurately. On the other hand, at the non-operative position, the hampering piece 168 is inclined in the paper feeding direction toward the nipping position of the first roller 130 and the second roller 132, and permits feeding of the paper in the manner to be described and conducts it toward the nipping site of the rollers 130 and 132. The first feed means 160 is provided with a first feed roller 174 to be rotated in the direction shown by an arrow 172 (Figures 2 and 3-A). The first feed roller 174 is adapted to be selectively held in an operative state shown by a solid line in Figure 2 and also in Figure 3-A and a non-operative state shown by a two-dot chain line in Figure 2 and also in Figure 3-B. In more detail, an oscillating arm 178 is oscillably mounted via a pin member 176,and the first feed roller 174 is mounted rotatably on one end portion of the oscillating arm 178. An output portion 180a of an electromagnetic solenoid 180 is pivotably linked to the other end portion of the oscillating arm 178 via a pin member 182. A coil spring 184 is disposed between the other end portion of the oscillating arm 178 and a main body portion 180b of the electromagnetic solenoid 180 in a manner to surround the output portion 180a. When the electromagnetic solenoid 180 is in the deenergized state, the feed roller 174 makes contact with the paper receiving stand 150 (more specifically, the copying paper on the receiving stand 150) mainly by its own weight and acts on the upper surface of the paper receiving stand (namely, the feed roller 174 is at the aforesaid operative state). When the electromagnetic solenoid 180 is energized, the oscillating arm 178 is pivoted in the direction shown by an arrow 186 against the biasing force of the coil spring 184 to move the feed roller 174 upwardly away from the paper receiving stand (the paper on the paper receiving stand 150) (namely, the feed roller 174 is held at the aforesaid non-operative state). The illustrated second feed means 162 has a second feed roller 190 to be rotated in the direction shown by an arrow 188 (Figures 2 and 3-B). The second feed roller 190 is adapted to be selectively held in a non-operative state shown in Figures 2 and 3-A and an operative state shown in Figure 3-B. Specifically, substantially like the first feed means 162, an oscillating arm 194 is oscillably mounted via a pin member 192, and the second feed roller 190 is pivotably mounted on one end portion of the oscillating arm 194. An output portion 196a of an electromagnetic solenoid 196 is pivotably linked to the other end portion of the oscillating arm 194 via a pin member 198. A coil spring 200 is disposed between the other end portion of the oscillating arm 194 and a main body portion 196a of the electromagnetic solenoid 196 in a manner to surround the output portion 196a. Thus, when the electromagnetic solenoid 196 is in the deenergized state in the second feed means 162, the second feed roller 190 moves away downwardly from the paper receiving stand 150 mainly by its own weight and is held in the aforesaid non-operative state (by the contacting of the oscillating arm 194 with a fixed pin 201). When the electromagnetic solenoid 196 is energized, the oscillating arm 194 is pivoted in the direction shown by an arrow 202 against the biasing force of the coil spring 200 to cause the second feed roller 190 to contact the lowermost paper sheet on the paper receiving stand 150 through an opening 204 formed in the paper receiving stand 150, and the feed roller 190 is held in the operative state in which it acts on the lower surface of the lowermost paper. The illustrated overlapping feed preventing means 133 will be described with reference mainly to Figure 4. The first roller 130 of the overlapping feed preventing means 133 is mounted on a shaft member 206 positioned on an upper side, and the second roller 132, on a shaft member 208 positioned on a lower side. The first roller 130 and the second roller 132 are adapted to rotate via a driving system 210 as will be described hereinafter. Gears 214 and 216 are attached to a shaft member 212 to be rotated in the direction shown by an arrow 211 and acting as an input shaft. One gear 214 is kept in mesh with a gear 224 mounted on a shaft member 222 via gears 218 and 220. The gear 226 is attached to a shaft member 222, and is kept in mesh with an input gear 230 of a first electromagnetic clutch means 228 mounted on the shaft member 206. The other gear 216 is in mesh with an input gear 234 of a second electromagnetic clutch means 232 mounted on the shaft member 206. Hence, upon energization of the first electromagnetic clutch means 228, the driving force from the shaft member 212 is transmitted to the shaft member 206 via the gears 214, 218, 220, 224, 226 and 230. On the other hand, when the second electromagnetic clutch means 232 is energized, the driving force from the shaft member 212 is transmitted to the shaft member 206 via the gears 216 and 234. A gear 236 is further mounted on the shaft member 206, and is kept in mesh with a gear 244 mounted on the shaft member 242 via gears 238 and 240. A nearly ⊐-shaped support 246 is pivotably mounted on the shaft member 242, and the shaft member 208 is rotatably mounted on the support 246. A gear 248 mounted on the shaft member 242 is in mesh with a gear 250 mounted on the shaft member 208. Furthermore, a coil spring 252 is interposed between the support 246 and part of the copying paper, and biases the support 246 counterclockwise as viewed from right bottom in Figure 4. In other words, the coil spring 252 biases the second roller 132 toward the first roller 130. In the illustrated embodiment, the first roller 130 is mounted on the shaft member 206 via a first torque limiter mechanism 254, and the second roller 132, on the shaft member 208 via a second torque limiter mechanism 256. The first torque limiter mechanism 254 (or the second torque limiter mechanism 256) is known per se , and can be constructed, for example, of a combination of a driving boss member rotating as a unit with the shaft member 206 (or 208), a follower boss member rotatably relative to the shaft member 206 (or 208), and a coil spring put over the driving boss member and the follower boss member. The first roller 130 (or the second roller 132) is mounted on the follower boss member so as to rotate as a unit with it. The first torque limiter mechanism 254 and the second torque limiter mechanism 256 are nearly the same as those disclosed, for example, in Japanese Laid-Open Utility Model Publication NO. 96333/1985 . The winding direction of the coil spring in the first torque limiter mechanism 254 is opposite to that of the coil spring in the second torque limiter mechanism 256. Now, with reference to Figures 2, 3-A, 3-B and 4, the operation and advantage of the paper re-feed means 119 mentioned above will be described. When a copying paper having an image formed on one surface is to be conducted to the paper receiving stand 150 through the paper returning passage, the paper re-feed means 119 is held in the state shown by a solid line in Figure 2. Specifically, the electromagnetic solenoids 180 and 196 are in the deenergized state, the feed roller 174 of the first feed means 160 is held in the aforesaid operative state, and the feed roller 190 of the second feed means 162 is held in the aforesaid non-operative state. Thus, when as stated above, the copying paper having an image formed on one surface is conducted to the paper receiving stand 150 through the paper returning passage and moved over the paper receiving stand 150 to the feed roller 174, the feed roller 174 acts on the upper surface of the copying paper. As a result, the copying paper is moved toward the hampering piece 168 by the action of the feed roller 174 rotating in the direction shown by arrow 172. When the leading edge of the copying paper is moved to the hampering piece 168 at the operative position, it abuts against the hampering piece 168 to hamper the movement of the copying paper. Upon abutting, slippage is created between the paper and the feed roller 174 and the paper is accurately stopped without bending. When the copying paper is thus received, the electromagnetic solenoid 180 is energized, and then a pair of width matching members (not shown) are moved reciprocatingly in the widthwise direction of the copying paper (the direction perpendicular to the sheet surface in Figures 1 and 2). When the electromagnetic solenoid 180 is energized, the oscillating arm 178 is pivoted in the direction shown by an arrow 186 (Figure 2). Consequently, the feed roller 174 is held in the aforesaid non-operative state, and moves upwardly away from the copying paper on the paper receiving stand 150. Thereafter, the pair of width matching members (not shown) are caused to reciprocate and by the action of the width matching member, the widthwise position of the copying paper is adjusted. After the adjustment of the widthwise position of the paper is over, the electromagnetic solenoid 180 is deenergized (and therefore, the feed roller 174 is again brought into the aforesaid operative state). The above operation is repeated, and a required number of copying paper sheets are stacked on the paper receiving stand 150 as shown in Figure 2. At the time of paper receiving as described above, the first and second electromagnetic clutch means 228 and 232 of the overlapping feed preventing means 133 are deenergized, and therefore, the first roller 130 and the second roller 132 are kept from rotating. When the paper sheets received in the stacked state on the paper receiving stand 150 are fed one by one from the uppermost one, the paper re-feed means 119 is held in a first feeding condition shown in Figure 3-A. Specifically, the electromagnetic solenoid 180 is deenergized, and the first feed means 160 is held in the aforesaid operative state. Furthermore, the electromagnetic solenoid 196 is deenergized to hold the second feed means 162 in the aforesaid non-operative state. Moreover, the hampering piece 168 is brought to the non-operative position from the above operative position. In addition, the first electromagnetic clutch means 128 in the overlapping feed preventing means 133 is energized. When the electromagnetic solenoid 180 is deenergized, the feed roller 174 rotating in the direction of arrow 172 acts on the uppermost copying paper in the stack to feed the uppermost paper toward the overlapping feed preventing means 133. When the first electromagnetic clutch means 128 is energized, the driving force of the gear 214 rotating in the direction of arrow 211 is transmitted to the shaft member 206 via the gears 218, 220, 224, 226 and 230 rotating as shown by solid line arrows to rotate the shaft member 206 as shown by a solid line arrow. With this, the first roller 130 is also rotated in the direction of arrow 258 via the first torque limiter mechanism 254 (see Figure 3-A also). When the shaft member 206 is so rotated, its driving force is transmitted to the shaft member 208 via the gears 236, 238, 240, 244, 248 and 250 rotating as shown by solid line arrows, and the shaft member 208 is rotated as shown by a solid line arrow. Accordingly, when the uppermost paper is fed as mentioned above, the driving force of the shaft member 208 is not transmitted to the second roller 132 via the second torque limiter mechanism 256. The second roller 132 moves following the rotation of the first roller 130 in the direction of arrow 258, and the uppermost paper is conveyed toward the paper conveying passage by the action of the first roller 130 and the second roller 132. On the other hand, when a plurality of copying paper sheets are fed from the top of the stack, the coil spring in the second torque limiter mechanism 256 contracts, and the driving force of the shaft member 208 is transmitted to the second roller 132 via the second torque limiter mechanism 256. Thus, the second roller 132 rotates in the direction shown by an arrow 260 indicated by a two-dot chain line. As a result, the first roller 130 acts on the uppermost paper to feed it toward the paper conveying passage. The second roller 132, on the other hand, acts on the paper beneath the uppermost one and sends it back to the paper receiving stand 150, and only the uppermost paper is fed toward the paper conveying passage by the first roller 130. On the other hand, when the copying paper sheets received in the stacked state on the paper receiving stand 150 are to be fed one by one from the lowermost one, the paper re-feed means 119 is held in a second feed condition shown in Figure 3-B. Specifically, the electromagnetic solenoid 180 is energized and the first feed means 160 is held in the aforesaid non-operative state. At the same time, the electromagnetic solenoid 196 is energized to hold the second feed means 162 in the aforesaid operative state. Moreover, the hampering piece 168 is brought to the above non-operative position from the operative position. In addition, the second electromagnetic clutch means 232 in the overlapping feed preventing means 133 is energized. Upon energization of the electromagnetic solenoid 196, the feed roller 190 acts on the lowermost paper in the stack, and by the action of the feed roller 190 rotating in the direction of arrow 188, the lowermost paper is fed toward the overlapping feed preventing means 133. When the second electromagnetic clutch means 232 is energized, the driving force of the gear 216 rotating in the direction of arrow 211 shown by a broken line is transmitted to the shaft member 206 via the gear 234 to rotate the shaft member 206 as shown by a broken line arrow. The driving force of the shaft member 206 is further transmitted to the shaft member 208 via the gears 236, 238, 240, 244, 248 and 250 rotating as shown by broken line arrows. With it, the second roller 132 is also rotated in the direction of arrow 262 shown by a broken line via the second torque limiter mechanism 256 (see Figure 3-B also). Hence, when the lowermost paper is fed as above, the driving force of the shaft member 206 is not transmitted to the first roller 130 via the first torque limiter mechanism 254. The first roller 130 moves following the action of the second roller 132 rotating in the direction of arrow 262 shown by the broken line, and the lowermost paper is conveyed toward the paper conveying passage by the action of the second roller 132 and the first roller 130. On the other hand, when a plurality of copying paper sheets are fed from the lowermost one as described above, the coil spring of the first torque limiter mechanism 254 contracts and the driving force of the shaft member 206 is transmitted to the first roller 130 via the first torque limiter mechanism 254 to rotate the first roller 130 in the direction shown by an arrow 264 indicated by a two-dot chain line. Consequently, the second roller 132 acts on the lowermost paper and conveys it toward the paper conveying passage. On the other hand, the first roller 130 acts on the paper existing above it and sends it back to the paper receiving stand 150. Only the lowermost paper is fed toward the paper conveying passage by the action of the second roller 132. Accordingly, in the paper re-feed means 119 having the structure described above, copying paper sheets received in the stacked state on the paper receiving stand 150 can be fed accurately one by one successively from the uppermost or lowermost one. Since the paper re-feed means 119 is of such a structure that copying paper sheets are received in the stacked state and then fed one by one, its first feed means 160 can be constructed for example, as shown in the specification and drawings of Japanese Patent Application No. 207940/1984 (entitled: ELECTROSTATIC COPYING APPARATUS). Specifically, it may be constructed such that the oscillating arm is actuated by two electromagnetic solenoids, and the feed roller is held in a first operative state (in which it acts on the copying paper relatively weakly) when the two electromagnetic solenoids are deenergized; it is held in a non-operative state (in which it moves away from the copying paper) when one of the electromagnetic solenoids is energized; and that it is held in a second operating state (in which it acts on the copying paper relatively strongly) when the other electromagnetic solenoid is energized. Structure of Document Sending Device in the above described Embodiment Again, with reference to Figure 1, the document sending device disposed on the upper surface of the main copying system 2 will be described. The illustrated document sending device 3 has a nearly box-like housing 270. An intermediate portion of the housing 270 in the left-right direction is slightly lower than its both end portions, and this intermediate upper wall 272 acts both as a document receiving stand on which documents to be copied are placed and as a document discharge section to which the documents after exposure are discharged. Document feeding means 274 is provided at the right end portion of the intermediate upper wall 272. The document feeding means 274 is disposed at the upper end of the housing 270 so as to act on the under surfaces of the documents placed on the upper surface of the intermediate upper wall 272 and comprised of a pair of rollers 276 and 278 and a feed belt 280 wrapped over these rollers 276 and 278. Above the roller 278, a separation roller 282 for preventing overlapping feed of documents is provided. As will be described in detail hereinafter, the feed belt 280 is moved in the direction shown by an arrow 284, and the separation roller 282 cooperating with the feed belt 280 is rotated in the direction shown by an arrow 286. Documents fed from the document feeding means 274 are conveyed through the exposure area on the transparent plate 6 in the main copying system 2 by the action of a document conveying means 288. The illustrated document conveying means 288 is provided with a conveyor belt mechanism 290 having a pair of rollers 292 and 294 disposed on both sides of the transparent plate 6 and an endless belt 296 wrapped over the pair of rollers 292 and 294. The documents exposed in the exposure area are then discharged onto the intermediate upper wall 272 by the action of a first document discharge means 298 defining a first document discharge passage or a second document discharge means 300 defining a second document discharge passage. The illustrated first document discharge means 298 includes a pair of conveyor rollers 302 and a pair of discharge rollers 304. The second document discharge means 300 includes a pair of conveyor rollers 306, a reversal conveying mechanism 308, a pair of conveyor rollers 310 and the pair of discharge rollers 304. The reversal conveying mechanism 308 has an intermediate roller 314 to be rotated in the direction shown by an arrow 312, a first roller 316 and a second roller 318 cooperating with the intermediate roller 314, a pair of document holding plates 320 and a returning roller 322. The returning roller 322 is adapted to be rotated in the direction shown by an arrow 324 and is free to move between a non-operative position shown by a solid line in Figure 1 (at which it moves away from the pair of document holding plates 320) and an operative position shown by a two-dot chain line in Figure 1 (at which it projects between the pair of document holding plates 320 and acts on the document held by these plates). In the illustrated document sending device 3, a document conveyance switching means 326 is further disposed downstream of the conveyor belt mechanism 290. The document conveyance switching means 326 comprises a switching guide member 328 adapted to be held selectively at a first position shown by a solid line in Figure 1 and a second position shown by a two-dot chain line in Figure 1. The switching guide member 328 is held at the first position when the documents are discharged through the first document discharge passage, and at the second position when the documents are discharged through the second document discharge passage.

Claims: Claims for the following Contracting States : FR, GB, NL A device for feeding sheet materials comprising a receiving stand (150) for receiving sheet materials (P) in the stacked state, a first feed means (160) disposed above the receiving stand (150), and a second feed means (162) disposed below the receiving stand (150); characterized in that the first feed means (160) is selectively held in an operative state in which it acts on the upper surface of the uppermost sheet material (P) on the receiving stand (150) and a non-operative state in which it moves away from the sheet materials (P) on the receiving stand (150); the second feed means (162) is selectively held in an operative state in which it acts on the under surface of the lowermost sheet material (P) on the receiving stand (150) and a non-operative state in which it moves away from the sheet materials on the receiving stand (150); in a first feeding state, the first feed means (160) is held in the operative state and the second feed means (162) is held in the non-operative state whereby the sheet materials (P) are successively fed from the uppermost one in the stack by the action of the first feed means (160); and in a second feeding state, the first feed means (160) is held in the non-operative state and the second feed means (162) is held in the operative state whereby the sheet materials (P) are fed successively from the lowermost one in the stack by the action of the second feed means (162). The device of claim 1, characterized in that overlapping feed preventing means (133) for preventing overlapping feed of the sheet materials (P) delivered from the receiving stand (150), said overlapping feed preventing means (133) is provided with a first roller (130) and a second roller (132) which coact to prevent overlapping feed of the sheet materials (P). The device of claim 2, characterized in that a first torque limiter mechanism (254) and a second torque limiter mechanism (256) are annexed respectively to the first roller (130) and the second roller (132); in the first feeding state, the overlapping feed preventing means (133) prevents overlapping feed of the sheet materials (P) fed from the uppermost one in the stack by rotating the first roller (130) in the sheet feeding direction and the second roller (132) in a direction opposite to the rotating direction of the first roller (130) via the second torque limiter mechanism (256); and in the second feeding state, the overlapping feed preventing means (133) prevents the overlapping feed of the sheet materials (P) fed from the lowermost one in the stack by rotating the second roller (132) in the sheet feeding direction and the first roller (130) in a direction opposite to the rotating direction of the second roller (132) via the first torque limiter mechanism (254). The device of claim 1, characterized in that the receiving stand (150) receives sheet materials (P) in the stacked state in a re-feed means (119) in an electrostatic copying apparatus, said re-feed means (119) being designed to receive sheet materials (P) having an image formed on one surface while being conveyed through a conveying passage (48) and re-feeding the received sheet materials (P) one by one to said conveying passage. The device of claim 4, characterized in that the re-feed means (119) is adapted to receive sheet materials (P) having a copied image formed on one surface in the stacked state on said receiving stand (150) with the image-bearing surfaces facing upward or downward, when the sheet materials (P) are received on the receiving stand (150) with their image-bearing surfaces facing upward, they are fed from the uppermost one in the stack by the action of the first feed means (160); and when the sheet materials (P) are received on the receiving stand (150) with their image-bearing surfaces facing downward, they are fed from the lowermost one in the stack by the action of the second feed means (162). Claims for the following Contracting State : DE A device for feeding sheet materials comprising a receiving stand (150) for receiving sheet materials (P) in the stacked state, a first feed means (160) disposed above the receiving stand (150), and a second feed means (162) disposed below the receiving stand (150); characterized by the first feed means (160) being selectively held in an operative state in which it acts on the upper surface of the uppermost sheet material (P) on the receiving stand (150) and a non-operative state in which it moves away from the sheet materials (P) on the receiving stand (150); the second feed means (162) being selectively held in an operative state in which it acts on the under surface of the lowermost sheet material (P) on the receiving stand (150) and a non-operative state in which it moves away from the sheet materials on the receiving stand (150); in a first feeding state, the first feed means (160) being held in the operative state and the second feed means (162) being held in the non-operative state whereby the sheet materials (P) are successively fed from the uppermost one in the stack by the action of the first feed means (160); and in a second feeding state, the first feed means (160) being held in the non-operative state and the second feed means (162) being held in the operative state whereby the sheet materials (P) are fed successively from the lowermost one in the stack by the action of the second feed means (162); and further characterized by overlapping feed preventing means (133) for preventing overlapping feed of the sheet materials (P) delivered from the receiving stand (150), said overlapping feed preventing means (133) being provided with a first roller (130) and a second roller (132) which coact to prevent overlapping feed of the sheet materials (P). The device of claim 1, characterized in that a first torque limiter mechanism (254) and a second torque limiter mechanism (256) are annexed respectively to the first roller (130) and the second roller (132); in the first feeding state, the overlapping feed preventing means (133) prevents overlapping feed of the sheet materials (P) fed from the uppermost one in the stack by rotating the first roller (130) in the sheet feeding direction and the second roller (132) in a direction opposite to the rotating direction of the first roller (130) via the second torque limiter mechanism (256); and in the second feeding state, the overlapping feed preventing means (133) prevents the overlapping feed of the sheet materials (P) fed from the lowermost one in the stack by rotating the second roller (132) in the sheet feeding direction and the first roller (130) in a direction opposite to the rotating direction of the second roller (132) via the first torque limiter mechanism (254). The device of claim 1, characterized in that the receiving stand (150) receives sheet materials (P) in the stacked state in a re-feed means (119) in an electrostatic copying apparatus, said re-feed means (119) being designed to receive sheet materials (P) having an image formed on one surface while being conveyed through a conveying passage (48) and re-feeding the received sheet materials (P) one by one to said conveying passage. The device of claim 3, characterized in that the re-feed means (119) is adapted to receive sheet materials (P) having a copied image formed on one surface in the stacked state on said receiving stand (150) with the image-bearing surfaces facing upward or downward, when the sheet materials (P) are received on the receiving stand (150) with their image-bearing surfaces facing upward, they are fed from the uppermost one in the stack by the action of the first feed means (160); and when the sheet materials (P) are received on the receiving stand (150) with their image-bearing surfaces facing downward, they are fed from the lowermost one in the stack by the action of the second feed means (162).

Inventors: FUJIOKA TADASHI, UJINO KOJI, FUJIOKA, TADASHI, UJINO, KOJI
Applicants: MITA INDUSTRIAL CO LTD, MITA INDUSTRIAL CO. LTD.
Application year: 1987
Main classification: G03G15
IPC codes: G03G15