ELECTROSTATIC COPYING APPARATUS

Abstract: An electrostatic copying apparatus of the type adapted to convey a copying paper sheet through a copying paper conveying passage (58) thereby to form an image on one surface of the sheet, selectively introduce it into a copying paper returning passage (110), return it to a copying paper re-sending means (120) through the returning passage (110), and again feed it into the paper conveying passage (58) from the re-sending means (120) so as to form an image on the other surface of the paper sheet. The paper resending means comprises a copying paper receiving stand (122) for receiv­ ing copying paper sheets and a delivery means (126) a disposed above the receiving stand. The delivery means is selectively maintained in a non-operting state in which it moves away from the copying paper received on the receiving stand, a first operating state in which it acts relatively weakly on the copying paper received on the receiving stand, and a second operating state at which it acts relatively strongly on the copying paper received on the receiving stand. Also provided are an improved mechanism (178) for preventing feeding of papers in the superposed state and an improved copying paper detecting mechanism (282) applicable to various types of electrostatic copying apparatus. An improved electrostatic copying apparatus of the aforesaid type which permits effective detection of the arrival of a copying paper at the paper re-sending means (120).

Description: BACKGROUND OF THE INVENTION This invention relates to an electrostatic copying apparatus of the kind referred to in the precharacterizing portion of claims 1 and 19, respectively. Such an electrostatic copying apparatus is known from DE-B-2 605 822. As document copying has been diversified in recent years, an electrostatic copying apparatus of the type capable of forming a copied image on both surfaces of a copying paper sheet has been proposed and come into commercial acceptance. This type of electrostatic copying apparatus, as is well known to those skilled in the art, comprises a copying paper conveying passage, a copying paper feeding means for feeding copying paper to the copying paper conveying passage, a copying paper returning passage, and a copying paper re-sending means for receiving the copying paper sheet returned through the copying paper returning passage and re-sending the received copying paper sheet to the copying paper conveying passage, and is adapted to form a copied image on both surfaces of the copying paper sheet in the following manner. The copying paper sheet fed to the paper conveying passage from the paper feeding means is conveyed through the paper conveying passage and during this conveyance, an image is formed on one surface of the paper sheet. The paper sheet having the image formed on its one surface is then selectively introduced into the paper returning passage and sent to the paper re-sending means. The paper sheet thus received in the paper re-sending means is resent to the paper conveying passage by the action of the paper re-sending means. While it is again conveyed through the paper conveying passage, an image is formed on the other surface of the copying paper sheet. As a result, the desired images are formed on both surfaces of the copying paper sheet fed from the paper feeding means. The aforesaid type of electrostatic copying apparatus known in the art has the following inconveniences or defects. Firstly, the paper returning means usually includes a copying paper receiving stand for receiving copying paper sheets returned through the paper returning passage. To receive the copying paper sheets in the desired stacked state on the paper receiving stand, the copying paper sheets should be conveyed with a relatively weak sending force. On the other hand, in order to send the uppermost sheet of the stack received on the paper receiving stand toward the paper conveying passage, it should be delivered with a relatively strong sending force. In the conventional electrostatic copying apparatus of this type, the paper returning means further includes auxiliary conveying rollers for receiving the copying paper sheets on the paper receiving stand in the desired conditions (these auxiliary conveying rollers act relatively weakly on the copying paper sheet and convey it) and delivery rollers for delivering the copying paper sheet from the paper receiving stand (the delivery rollers act relatively strongly on the copying paper sheet and deliver it), and is constructed such that the auxiliary conveying rollers and the delivery rollers are each selectively held in an operating state in which they act on the copying paper sheet and in a non-operating state in which they are apart from the copying paper sheet. Specifically, it is of such a construction that when the copying paper sheet is received by the receiving stand, the auxiliary conveying rollers are maintained in the operating state and the delivery rollers, in the non-operating state; that when the position of the copying paper sheet in the width direction is set right, the auxiliary conveying rollers and the delivery rollers are both kept in the non-operating states; and that when the copying paper sheet is delivered from the receiving stand, the auxiliary conveying rollers are maintained in the non-operating state and the delivery rollers, in the operating state. Thus, in the conventional electrostatic copying apparatus, the auxiliary conveying rollers and the delivery rollers exist independently, and a mechanism is required which selectively maintains the auxiliary conveying rollers and the delivery rollers in the operating state and in the non-operating states. Accordingly, the structure and controlling of the paper re-sending means become complex. Secondly, electrostatic copying apparatuses, not necessarily limited to the above-described type, include a copying paper detecting mechanism for detecting a copying paper sheet conveyed through the paper conveying passage, etc. in order to detect paper jamming in the paper conveying passage or elsewhere. This type of paper detecting mechanism known in the art generally includes a detecting means comprising a combination of a microswitch or light emitting element and a light-receiving element and is constructed such that the detecting means directly detects passage of the copying paper sheet. For example, to detect paper jamming in the paper returning passage of the aforesaid type of electrostatic copying apparatus, it is necessary to annex a copying paper detecting mechanism to the paper receiving stand in relation to the paper returning means and to detect the arrival of the copying paper sheet. However, the conventional paper detecting mechanism can detect the first sheet of the paper stack, but cannot detect the second and subsequent sheets because the copying paper sheets are stacked on the receiving stand. DE-B-2 605 822 discloses an electrostatic copying apparatus adapted to introduce a copying paper sheet having an image formed on one surface thereof during conveyance through a copying paper conveying passage into a copying paper returning passage, return the copying paper sheet through the paper returning passage to a copying paper re-sending means disposed below the paper returning passage, and to feed it again to the paper conveying passage from the re-sending means in order to form an image on the other surface, said re-sending means including a copying paper receiving stand for receiving copying paper sheets having an image formed on one surface in the stacked state, a width matching means for matching the width-wise positions of the copying paper sheets received on the paper receiving stand and a delivery means disposed above the paper receiving stand. SUMMARY OF THE INVENTION It is the object of this invention to improve the above-mentioned electrostatic copying apparatus such that it can permit feeding of a copying paper sheet returned through a paper returning passage to a paper conveying passage in the desired manner by a relatively simple structure and a relatively simple and easy controlling operation, which can - by means of a copying paper detecting mechanism - accurately detect the arrival of a copying paper sheet at a copying paper receiving stand on which copying paper sheets are received in the stacked state and which is capable of forming an image on both surfaces of a copying paper sheet, which can accurately detect the arrival of a copying paper sheet returned through a copying paper returning passage at a copying paper re-sending means. According to the present invention this object is accomplished with an electrostatic copying apparatus as claimed. Dependent claims are directed on features of preferred embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a sectional view which shows in a simplified form the main constituent elements of an electrostatic copying apparatus improved in various respects in accordance with the present invention; Figure 2 is a sectional view showing a copying paper re-sending means and its vicinity in the electrostatic copying apparatus of Figure 1; Figure 3 is a top plan view showing the paper re-sending means of Figure 2 partly in section; Figure 4 is a sectional view taken along line IV-IV of Figure 3; Figure 5 is a perspective view, partly broken away, of the front portion of the paper re-sending means of Figure 3; Figure 6 is a side elevation of the front portion of the paper re-sending means of Figure 5 when viewed from ahead of the copying apparatus; Figure 7 is a perspective view for illustrating the actuation of one of electromagnetic solenoids of a copying paper re-sending means; Figure 8 is a side elevation of the state shown in Figure 7 as viewed from ahead of the copying apparatus; Figure 9 is a perspective view showing the actuation of the other electromagnetic solenoid of the paper re-sending means; Figure 10 is a side elevation of the state of Figure 9 as viewed from ahead of the copying apparatus; Figure 11 is a perspective view showing an actuating mechanism in a modified example of the paper re-sending means; Figures 12 and 13 are views for illustrating the states wherein one electromagnetic solenoid and the other electromagnetic solenoid in the actuating mechanism in Figure 11 are in operation; Figure 14 is a top plan view showing a copying paper re-sending means and its vicinity in the modified example of the electrostatic copying apparatus constructed in accordance with this invention; Figure 15 is a perspective view showing the front part of a copying paper receiving stand of the paper re-sending means of Figure 14; Figure 16 is a sectional view taken along line XVIII-XVIII of Figure 14; and Figure 17 is a side elevation, partly in section, of a copying paper re-sending means and its vicinity of an electrostatic copying apparatus equipped with a modified example of a deflecting-conveying means. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The invention will now be described in detail with reference to the accompanying drawings. Outline of the General Structure and Operation of the Electrostatic Copying Apparatus First of all, the general structure of one embodiment of an electrostatic copying apparatus on which various improvements have been made in accordance with this invention will be described. With reference to Figure 1, the illustrated electrostatic copying apparatus includes a nearly rectangular housing 2. A stationary transparent plate 4 on which to place a document (not shown) to be copied and an openable document holding member 6 for covering the transparent plate 4 and the document to be placed on it are disposed on the top surface of the housing 2. A rotating drum 8 having an electrostatographic material on its peripheral surface is rotatably mounted nearly centrally within the housing 2. Around the rotating drum 8 to be rotated in the direction shown by an arrow 10 are defined a charging zone 12, an exposing zone 14, a developing zone 16, a transferring zone 18 and a cleaning zone 20 defined in this order in the direction of the arrow 10. A charging corona discharge device 22 is disposed in the charging zone, and a developing device 24 is disposed in the developing zone 16. A transferring corona discharge device 26 and a peeling corona discharge device 28 are provided in the transferring zone 18. In the cleaning zone 20, a charge eliminating lamp 30 and a residual toner removing blade 32 are set up. An optical system shown generally at 34 is provided above the rotating drum 8. The optical system 34 comprises a movable document illuminating lamp 36, a first movable reflecting mirror 38, a second movable reflecting mirror 40, a third movable reflecting mirror 42, a stationary lens assembly 44 and a stationary reflecting mirror 46. During scanning exposure, the movable document illuminating lamp 36 and the first movable reflecting mirror 38 are moved at a predetermined speed V from a start-of-scan position shown by a solid line to a desired position (for example, a maximum end-of-scan position shown by a two-dot chain line) substantially horizontally. The second movable reflecting mirror 40 and the third movable reflecting mirror 42 are moved at a speed half of the above predetermined speed (V/2) from a start-of-scan position shown by a solid line to a desired position (for example, a maximum end-of-scan position shown by a two-dot chain line) substantially horizontally. During this action, the document placed on the transparent plate 4 is illuminated by the document illuminating lamp 36, and the light reflected from the document is reflected successively by the first, second and third reflecting mirrors 38, 40 and 42 and reaches the lens assembly 44. Then it is reflected by the stationary reflecting mirror 46 and projected onto the electrostatographic material in the exposing zone 14. When the scanning exposure is over, the movable document illuminating lamp 36 and the first, second and third reflecting mirrors 38, 40 and 42 are returned to the start-of-scan positions shown by the solid lines. In one end portion (the right end portion in Figure 1) of the housing 2, a copying paper feeding means shown generally at 48 is provided. The paper feeding means 48 includes a lower cassette receiving section 50a, an intermediate cassette receiving section 50 and an upper cassette receiving section 50c for selectively and detachably receiving several types of copying paper cassettes 52 containing copying paper sheets of different sizes. Delivery rollers 54a, 54b and 54c for delivering the copying paper sheets one by one from the paper cassettes 52 are provided respectively in the lower, intermediate and upper cassette receiving sections 50a, 50b and 50c. The copying paper delivered from the paper cassette 52 mounted on the lower cassette receiving section 50a is introduced into a copying paper conveying passage generally shown at 58 through a copying paper delivery passage 56a. The copying paper delivered from the paper cassette 52 mounted on the intermediate cassette receiving section 50b is introduced into the paper conveying passage 58 through the paper delivery passages 56b and 56a. The copying paper delivered from the paper cassette 52 mounted on the upper cassette receiving section 50c is introduced into the paper conveying passage 58 through a copying paper delivery passages 56c and the paper delivery passages 56b and 56a. The paper delivery passage 56a is defined by the upstream portion of a guide plate 60 and a part of a guide plate 62. The paper delivery passage 56b is defined by a pair of guide plates 64. The paper delivery passage 56c is defined by a pair of guide plates 66. A pair of delivery rollers 68 are disposed between the upstream end of the paper delivery passage 56a and the downstream end of the paper delivery passage 56b, and a pair of delivery rollers 69, between the upstream end of the paper delivery passage 56b and the downstream end of the paper feed passage 56c. The paper conveying passage 58 extends nearly horizontally from right to left in Figure 1 from its upstream end 70 to its downstream end 72, and is defined by a copying paper conveying means, specifically by the downstream portion of the guide plate 60, the downstream portion of the guide plate 74, a pair of conveying rollers 76, a pair of guide plates 78, a pair of conveying rollers 80, a guide plate 82, the transferring zone 18 (an area between the rotating drum 8 and the transferring corona discharge device 26 and the peeling corona discharge device 28), a conveyer belt mechanism 84, a guide plate 86, a pair of heat-fixing rollers, a pair of guide plates 90 and a pair of conveying rollers 92 in the illustrated embodiment. A conveyance controlling means 94 is disposed adjacent to the downstream end 72 of the paper conveying passage 58. The conveyance controlling means 94 includes a lower movable guide member 98 and an upper movable guide member 100 defining a copying paper moving passage 96 between them. The lower movable guide member 98 and the upper movable guide member 100 are selectively held at a lowered position shown by a solid line and at an elevated position shown by a two-dot chain line. Downstream of the conveyance controlling means 94 is provided a copying paper discharging passage 104 having a pair of discharge rollers 102. A receiving tray 106 is mounted detachably at the other end (i.e., the left end portion in Figure 1) of the housing 2. In relation to the conveyance controlling means 94, a copying paper reversing passage shown generally at 108 and a copying paper returning passage shown generally at 110 are provided. The paper reversing passage 108 is defined by a pair of guide plates 112 and extends in a curved shape from its upstream end adjacent to the downstream end of the conveyance controlling means 94. At the upstream end of the paper reversing passage 108 is disposed a reversing roller 114 adapted to be held selectively at a non-operating position shown by a solid line and an operating position shown by a two-dot chain line. The paper returning passage 110 extends inclinedly somewhat in a downward direction from left to right in Figure 1 from its upstream end adjacent to the upstream end of the conveyance controlling means 94, and is defined by a copying paper returning means, specifically by a pair of guide plates 115, a pair of returning rollers 116, a pair of guide plates 117, a pair of returning rollers 118 and a guide plate 119 in the illustrated embodiment. It will be readily understood from Figure 1 that when the lower movable guide member 98 and the upper movable guide member 100 of the conveyance controlling means 94 are held at the lowered positions shown by solid lines, the paper conveying passage 58 and the paper discharge passage 104 are brought into communication with each other through the paper moving passage 96 in the conveyance controlling means 94. On the other hand, when the lower and upper movable guide members 98 and 100 are held at the elevated positions shown by two-dot chain lines, the paper conveying passage 58 and the paper reversing passage 108 are brought into communication with each other through the paper moving passage 96 of the controlling means 94 and at the same time, the paper reversing passage 108 and the paper returning passage 110 are brought into communication with each other through the moving passage 96 of the controlling means 94. The illustrated electrostatic copying apparatus further includes a copying paper re-sending means shown generally at 120 below the paper returning passage 110. The paper re-sending means 120 includes a substantially horizontally extending stand 122 for receiving copying paper, and a movement hampering means 124 for hampering the movement of the copying paper is provided at the front end (i.e., the right end in Figure 1) of the paper receiving stand 122. The movement hampering means 124 is adapted to be selectively held at a hampering position shown by a solid line and a receding position shown by a two-dot chain line. A delivery roller 126 is provided on the front end portion of the receiving stand 122. The delivery roller 126 is mounted so that it can freely move upwardly from its illustrated position contacting the upper surface of the paper receiving stand 122. Normally, the roller 126 is forced downwardly by a biasing action attributed to its own weight (if required, by using a suitable spring means). A copying paper re-feeding passage shown generally at 128 is provided which extends from the front end of the paper re-sending means 120 to the upstream end 70 of the paper conveying passage 58. The paper re-feeding passage 128 is defined by a copying paper re-feeding means, specifically by a guide plate 130, a conveying roller 132 which also performs a paper separating action in cooperation with a frictional member to be described hereinafter, a pair of re-feeding rollers 134, a pair of guide plates 136 and the upstream portion of the guide plate 74. The outline of the operation of the electrostatic copying apparatus described hereinabove is now described. The rotating drum 8 is rotated in the direction of the arrow 10. In the charging zone 12, the surface of the electrostatographic material on the rotating drum 8 is charged to a specific polarity by the charging corona discharge device 26, and in the exposing zone 14, the image of a document placed on the transparent plate 4 is scanned, exposed and projected onto the electrostatographic material by the optical system 34 to form a latent electrostatic image on the electrostatographic material. In the developing zone 16, a toner is applied to the latent electrostatic image on the electrostatographic material by the developing device 24 to develop the latent electrostatic image to a toner image. In the transferring zone 18, a copying paper sheet conveyed through the transferring zone 18 (the conveying of copying paper will be further described hereinbelow) is brought into contact with the surface of the electrostatographic material, and by the action of the transferring corona discharge device 26, the toner image on the electrostatographic material is transferred to the copying paper sheet. Thereafter, the copying paper is peeled from the electrostatographic material by the action of the peeling corona discharge device 28. The peeled copying paper is conveyed to the pair of heat-fixing rollers 88, and during passage between the rollers 88, the toner image is fixed to the copying paper. In the meantime, in the cleaning zone 20, light from the charge eliminating lamp 30 is illuminated onto the electrostatographic material to erase the residual charge on it. The residual toner is removed from the surface of the electrostatographic material by the action of a residual toner blade 32. The conveying of copying paper will now be described. First, with reference to the formation of an image only on one surface of a copying paper, the lower and upper movable guide members 98 and 100 of the conveyance controlling means 94 are held at the lowered positions shows by solid lines. A copying paper sheet introduced into the paper conveying passage 58 from the paper cassette 52 loaded into the lower cassette receiving section 50a, the intermediate cassette receiving section 50b or the upper cassette receiving section 50c is conveyed through the conveying passage 58. During this time, a toner image is transferred to the upper surface of the copying paper in the transferring zone 18, and the toner image is fixed to that surface of the copying paper by the action of the pair of heat-fixing rollers 88. As a result, an image is formed on one surface of the copying paper. The copying paper having an image formed on one surface is then introduced into the paper discharge passage 104 through the paper moving passage 96 in the conveyance controlling means 94, and discharged into the receiving tray 106 through the paper discharge passage 104. Thus, a copy having an image formed on its one surface is obtained. When an image is to be formed on both surfaces of copying paper, the lower and upper movable guide members 98 and 100 of the conveyance controlling means 94 are first held at the elevated positions shown by the two-dot chain lines. When the copying process is started, a copying paper introduced into the paper conveying passage from the paper cassette 52 loaded into the lower cassette receiving section 50a, the intermediate cassette-receiving section 50b or the upper cassette receiving section 50c is conveyed through the paper conveying passage 58. During this time, a toner image is transferred to one surface (the upper surface) of the copying paper in the transfering zone 18, and fixed onto one surface of the copying paper by the action of the heat-fixing rollers 88 to form an image on one surface of the copying paper. The copying paper from the paper conveying passage 58 is introduced into the paper reversing passage 108 through the paper moving passage 96 in the conveyance controlling means 94, and advances in the direction shown by an arrow 138 through the paper reversing passage 108. At this time, the under surface of the copying paper makes contact with one (102a) of the pair of discharge rollers 102. But since slippage is created between the discharge roller 102a and the copying paper, the copying paper can advance in the direction of arrow 138 in spite of the roller 102a being rotated in the direction of an arrow 140. When the trailing end of the copying paper has gone past the downstream end of the paper conveying passage 58, i.e. the nipping position of the pair of conveying rollers 92, the reversing roller 114 provided at the upstream end of the reversing passage 108 is held at the operating position shown by the two-dot chain line so that the copying paper is pushed against the discharge roller 102a. As a result, the trailing and leading ends of the copying paper are reversed by the action of the discharge roller 102a rotating in the direction of arrow 140, and the copying paper advances in the direction shown by an arrow 142. It is passed through one (92a) of the pair of conveying rollers 92 rotated in the direction of the arrow 140 and one (116a) of the pair of guide plates 116, and introduced into the paper returning passage 110 through which it advances. The reversing roller 114 in the paper reversing passage 108 is returned to the non-operating postion shown by the solid line at a suitable time after the copying paper has been introduced into the paper returning passage 110. The copying paper advanced through the paper returning passage 110 is conducted to the paper receiving stand 122 of the paper re-sending means 120 and advances on the receiving stand 122 to the right in Figure 1. The delivery roller 126 rotated in the direction shown by an arrows 144 acts on the copying paper to deliver it further to the right and thus cause the leading edge of the copying paper to abut against the movement hampering means 124 held at the hampering position shown by the solid line. This hampers the advancing of the copying paper, and the copying paper is stopped at a desired position on the paper re-sending means 120. Even when the delivery roller 126 is rotated in the direction of the arrow 144, slippage is created between the delivery roller 126 and the copying paper, and there is no further advancing of the copying paper. When a predetermined number of copying paper sheets have been returned to the paper re-sending means 120, the lower and upper movable guide members 98 and 100 of the conveyance controlling means 94 are returned to the lowered positions shown by the solid lines. The movement hampering means 124 in the paper re-sending means 120 is held at the receding position shown by the two-dot chain line, and by the action of the delivery roller 126 rotating in the direction of the arrow 144, the copying paper is delivered from the paper re-sending means 120 to the paper re-feeding passage 128. The copying paper sheets delivered to the paper re-feeding passage 128 are caused to advance one by one through the paper re-feeding passage 128 and again fed to the copying paper conveying passage 58. As can be easily understood from Figure 1, the copying paper is reversed as a result of passing through the nearly semicircular paper re-feeding passage and fed to the paper conveying passage 58 with its image-bearing surface down. It is then conveyed through the paper conveying passage 58. At this time, a toner image is transferred to the other surface of the copying paper (i.e. the upper surface) in the transferring zone 18, and fixed to the copying paper by the action of the pair of heat-fixing rollers 88. As a result, an image is formed on the other surface of the copying paper. Thereafter, the copying paper is introduced from the paper conveying passage 58 into the paper discharging passage 104 through the paper moving passage 96 in the conveyance controlling means 94, and discharged onto the receiving tray 106 through the paper discharge passage 104. Thus, a copy having an image formed on both surfaces is obtained. The structure and operation described above of the illustrated electrostatic copying apparatus do not constitute novel features improved in accordance with the present invention, but merely illustrate one example of electrostatic copying apparatus to which the present invention is applicable. Hence, a detailed description of these will be omitted in the present specification. Structure of the paper re-sending means and its vicinity Now, the structure of the paper re-sending means 120 improved in accordance with this invention will be described. With reference to Figures 2 and 3 together with Figure 1, the paper re-sending means 120 in the illustrated embodiment includes the copying paper receiving stand 122 adapted to receive copying paper sheets returned through the paper returning passage 110, the delivery roller 126 (constituting delivery means) disposed above the paper receiving stand 122, and a width matching means 146 for matching the widthwise positions of the paper sheets received on the paper receiving stand 122. The illustrated electrostatic copying apparatus includes a vertical front base plate (not shown) and a vertical rear base plate 148 (Figures 3 and 4) arranged in spaced-apart relationship in the forward-backward direction (a direction perpendicular to the sheet surface in Figure 2; a vertical direction in Figure 3), and the paper receiving stand 122 is disposed between the vertical front base plate and the vertical rear base plate 148. The paper receiving stand 122 is composed of a plate-like member, and extends substantially horizontally between the vertical front base plate and the vertical rear base plate 148. The illustrated width matching means 146 includes a pair of spaced movable matching members 150 only one of which is shown in Figure 2). The pair of movable matching members 150 are set up so that they can move freely in the widthwise direction of the paper sheets received on the receiving stand,i.e., the aforesaid forward-backward direction in the illustrated embodiment. More specifically, the pair of movable matching members 150 can move between a receiving position at which they receive the copying paper and a matching position at which they match the positions of the paper sheets in the widthwise direction by the action of the actuating mechanism 152. The delivery roller 126 is held selectively in any one of a non-operating state (the state shown by a two-dot chain line in Figures 7 and 8), a first operating state (the state shown in Figures 1, 2, 3, 5 and 6 and by a solid line in Figures 7 and 8) and a second operating state (the state shown in Figures 9 and 10). The delivery roller 126 can be formed of a sponge, for example. Correspondingly to the delivery roller 126, a frictional member 154 formed of a woven cloth is disposed on the upper surface of the receiving stand 122 with which the delivery roller 126 comes into contact (see Figures 6 to 8 and 10). The paper re-sending means 120 also includes copying paper movement hampering means 124. The illustrated movement hampering means 124 is composed of a pair of plate-like pieces 156 spaced from each other in the widthwise direction of the paper sheets received on the receiving stand, i.e. in the forward-backward direction (Figures 3 and 5). The plate-like pieces 156 are held selectively at a hampering position (the position shown in Figures 2 to 6 and 11 and by a solid line in Figure 1) and a receding position (the position shown in Figures 9, 10 and 12 and by a two-dot chain line in Figure 1). In the illustrated embodiment, a supporting shaft 158 is rotatably mounted across the vertical front base plate (not shown) at the forward end of the receiving stand 122 and the vertical rear base plate 148. The two opposite end portions of the supporting shaft 158 (the parts supported by the vertical front base plate and the vertical rear base plate 148) are circular in cross section, and its intermediate portion (the part extending between the vertical front base plate and the vertical rear base plate 148) are rectangular in cross section. The plate-like piece 156 is fixed to one side surface of the intermediate portion by a screw 160 (see Figure 4). The paper re-sending means 120 further includes an actuating mechanism 152 for moving the delivery roller 126 and the pair of plate-like pieces 156. With reference to Figures 2 to 5, mainly to Figure 5, the illustrated actuating mechanism 152 has a first oscillating member 162, a second oscillating member 164 and a third oscillating member 166. The first oscillating member 162 includes a supporting side wall 168 and a side wall 170 spaced from each other in the forward-backward direction and an intermediate wall 172 connecting the supporting side wall 168 and the side wall 170, and the supporting side wall 168 and the side wall 170 are rotatably mounted on a rotating shaft 176 (on which the conveying roller 132 of a mechanism for preventing feeding of copying paper sheets in the superposed state is mounted) through a bearing member 174 (see Figures 3 and 5). The supporting side wall 168 of the first oscillating member 162 is positioned nearly centrally of the receiving stand in its width direction, and extends rearwardly (to the left in Figures 2 and 3) from the forward end side of the receiving stand 122. The aforesaid delivery roller 126 is mounted rotatably on the forward end portion of the supporting side wall 168 via a shaft member 180 (therefore, the delivery roller 126 acts on the central part in the widthwise direction of a copying paper sheet received on the receiving stand 122). The second oscillating member 164 has side walls 182 and 184 spaced from each other in the forward-backward direction and an intermediate wall 186 connecting the two side walls 182 and 184, and the side walls 182 and 184 are rotatably mounted on the rotating shaft 176. In the illustrated embodiment, the second oscillating member 164 is disposed rearwardly (upwardly in Figure 3, and to the right in Figure 4) of that site of the rotating shaft 176 on which the first oscillating member 162 is mounted, and a spring member 188 comprised of a coil spring, for example, is interposed between the first oscillating member 162 and the second oscillating member 164. A rearwardly extending projection 190 is provided in the upper end part of the side wall 170 of the first oscillating member 162, and a projection 192 extending in a direction away from the rotating Shaft 176 is provided in the lower end part of the side wall 182 of the second oscillating member 164. The spring member 188 is engaged with the projection 190 of the first oscillating member 162 at one end and with the projection 192 of the second oscillating member at the other end. The spring member 188 acts to bias the second oscillating member 164 clockwise in Figures 5 and 6 relative to the first oscillating member 162. In the illustrated embodiment, a forwardly extending engaging projection 194 is further provided at the upper end part of the side wall 182 of the second oscillating member 164, and the engaging projection 194 is received in an arcuate elongate hole 196 formed in the side wall 170 of the first oscillating member 162. Accordingly, the first oscillating member 162 and the second oscillating member 164 can freely pivot relative to each other over a predetermined range. In other words, they can pivot relative to each other between a position at which the engaging projection 194 abuts against one end of the elongate hole 196 and a position at which the engaging projection 194 abuts against the other end of the elongate hole 196. The third oscillating member 166 is composed of an L-shaped member (see Figure 3) and fixed to the rear end portion of the supporting shaft 158. In relation to the third oscillating member 166, a pin member 200 (constituting an abutment portion) against which a part of the third oscillating member 166 can abut when the third oscillating member 166 pivots in the direction of an arrow 198 (Figures 9 and 10) is set firmly in the lower end portion of the side wall 184 of the second oscillating member 164. The illustrated actuating mechanism 152 further includes a first actuating means and a second actuating means composed of electromagnetic solenoids 202 and 204 respectively. A mounting member 206 is attached to the front surface of the vertical rear base plate 148, and the electromagnetic solenoid 202 constituting the first actuating means is mounted on the mounting member 206 (Figure 3). A short shaft 208 is set firmly in the front surface of the vertical rear base plate 148, and a revolving lever 210 is revolvably mounted on the forward end portion of the short shaft 208. One end portion 212a of the revolving lever 210 is connected to an output portion 216 of the electromagnetic solenoid 202 via a linking pin 214 (Figures 6, 8 and 10). A coil spring 218 (not shown in Figures 2, 3, 5, 7 and 9) is interposed between the electromagnetic solenoid 202 and the revolving lever 210 and covers the output portion 216. A projecting portion 222 having an abutting part 224 is provided in the revolving lever 210 (see Figures 6, 8 and 10). Hence, when the electromagnetic solenoid 202 is inoperative, the revolving lever 210 is held by the action of the coil spring 218 at an angular position at which the abutting part 224 of the projecting portion 222 abuts against the electromagnetic solenoid 202 (the position shown in Figures 2 to 6, 9 and 10, and the position shown by a two-dot chain line in Figures 7 and 8). In relation to the other end portion 212b of the revolving lever 210, a pin member 226 (constituting an abutment portion) against which the other end portion 212b of the revolving lever 210 can abut when the revolving lever 210 is pivoted in the direction shown by an arrow 225 (Figures 7 and 8) is set firmly in the forward end part of the side wall 170 of the first oscillating member 162. Accordingly, when the electromagnetic solenoid 202 is actuated, the revolving lever 210 is revolved in the direction shown by the arrow 225 (Figures 7 and 8) against the elastic biasing action of the coil spring 218, and the other end portion 212b of the revolving lever 210 abuts against, and thereby acts on, the pin member 226 provided in the first oscillating member 162. As a result, the first oscillating member 162 is pivoted about the rotating shaft 176 in a direction shown by an arrow 228 (Figures 7 and 8), namely clockwise in Figures 7 and 8. The electromagnetic solenoid 204 constituting the second actuating means is mounted on a plate-like mounting member 130 secured to the front surface of the vertical rear base plate 148 (Figure 3). One end portion of a linking member 234 is connected to the third oscillating member 166 through a pin member 232, and the other end portion of the linking member 234 is connected to an output portion 238 of the electromagnetic solenoid 204. A spring member 240 composed of, for example, a coil spring is interposed between the third oscillating member 166 and a part of the electrostatic copying apparatus. Accordingly, when the electromagnetic solenoid 204 is inoperative, the third oscillating member 166 is held at the position shown in Figures 2 to 6 by the action of the spring member 240. As will be understood from Figure 2, at this position, the pair of plate-like pieces 156 abut against the front end of the receiving stand 122 and thus the third oscillating member 166 is held at the aforesaid position. Furthermore, as can be understood from Figures 2, 4 and 5, the plate-like pieces 156 are held at an operating position at which they project upwardly from the upper surface of the receiving stand 122. On the other hand, when the electromagnetic solenoid 204 is actuated, the third oscillating member 166 is privoted in the direction shown by the arrow 198 (Figures 9 and 10) together with the supporting shaft 158 via the linking member 234 against the elastic biasing action of the spring member 240. As a result, a part of the third oscillating member 166 abuts against, and acts on, the pin member 200 provided in the second oscillating member 164, and the second oscillating member 164 is pivoted in the direction shown by an arrow 242 (Figure 10) about the rotating shaft 176 as a center. When the third oscillating member 166 is pivoted in the direction of the arrow 198, the supporting shaft 158 and the pair of plate-like pieces 156 mounted on it are likewise pivoted as a unit, and the plate-like pieces 156 are held at the receding position (the position shown in Figures 9 and 10) at which they have receded, and thus are apart, from the upper surface of the receiving stand 122. Modified embodiment of the paper re-sending means With reference to Figures 11 to 13, a modified embodiment of the paper re-sending means will be described. The illustrated paper re-sending means 302 includes a copying paper receiving stand 304, a delivery roller 306 disposed above the paper receiving stand 304 (constituting delivery means), an actuating mechanism 308 for moving the delivery roller 306 in the desired manner, a width matching means (not shown) for matching the widthwise position of a copying paper sheet, a copying paper movement hampering means 310 for hampering the movement of copying paper. In this modified embodiment, the structures of the actuating mechanism 308 and the movement hampering means 310 differ from those shown in Figures 1 to 12, but the structures of the other members are substantially the same as in the embodiment described hereinabove. With reference to Figures 11 and 12, a rotating shaft 312 is rotatably mounted between the vertical front base plate and the vertical rear base plate (not shown) of the electrostatic copying apparatus. The actuating mechanism 308 in the modified embodiment includes a pair of oscillating supporting members 314 and 316 which are oscillably mounted on the opposite end portions of the rotating shaft 312. A supporting shaft 318 are rotatably mounted between the end portions of the nearly L-shaped oscillating supporting members 314 and 316, and a pair of delivery rollers 306 constituting the delivery means are mounted on the supporting shaft 318. The delivery rollers 306 may be formed of, for example, sponge. A sprocket 320 is fixed to one end of the supporting shaft 318, and drivingly connected to a sprocket portion 326a of a power transmission member 324 fixed to one end portion of the rotating shaft 312 via a chain 322. And a sproket portion 326b of the power transmission member 324 is drivingly connected to a driving source (not shown) such as an electric motor via a chain 328. Thus, the driving power from a driving source (not shown) is transmitted to the delivery rollers 306 via a chain 328, the power transmission member 324, the chain 322 and the sprocket 320, and the delivery rollers 306 rotate in the direction of an arrow 330 (Figure 13). The actuating mechanism 308 includes a first actuating means and a second actuating means for moving the delivery roller 306 as is desired, and the first and second actuating means are respectively composed of electromagnetic solenoids 332 and 334. In the modified embodiment, as will be stated below, the electromagnetic solenoid 332 and 334 are disposed in relation to the oscillating supporting member 314 mounted on one end portion of the rotating shaft 312, but they may be disposed in relation to both the oscillating supporting members 314 and 316. The electromagnetic solenoids 332 and 334, substantially as in the embodiment shown in Figures 1 to 10, maintain the pair of delivery rollers 306 selectively in an inoperative state in which they are apart from the copying paper on the paper receiving stand 304, in a first operating state in which they act relatively weakly on the copying paper on the paper receiving stand 304, and in a second operating state in which they act relatively strongly on the copying paper received on the paper receiving stand. More specifically, a vertically extending elongate hole 336 is formed in the rear end portion of the oscillating supporting member 314, and a linking member 338 is provided through the elongate hole 336. The linking member 338 is adapted to move freely within and along the elongate hole 336. The output terminal 340 of the electromagnetic solenoid 332 constituting the first actuating means is connected to one end portion of the linking member 338, and the output terminal 342 of the electromagnetic solenoid 334 constituting the second actuating means, to the other end portion of the linking member 338. A spring member 344 is provided between the electromagnetic solenoid 332 and the one end of the linking member 338 and a spring member 346 is interposed between the electromagnetic solenoid 334 and the other end portion of the linking member 338. The width of the elongate hole 336 is slightly larger than the outside diameter of the linking member 338 so as to permit the oscillating movement of the linking member 338 which will be described below. Thus, when the electromagnetic solenoids 332 and 334 are in the inoperative state, the linking member 338 is positioned in the middle portion of the elongate hole 336b in the longitudinal direction (the vertical direction) (see Figure 11). Hence, the oscillating supporting member 314 becomes oscillable and is rotated counterclockwise in Figure 13 about the rotating shaft 312 as a center by the weights of the delivery rollers 306, the supporting shaft 318. etc. The delivery rollers 306 abut against the upper surface of the paper receiving stand 304 (the upper surface of a copying paper sheet on the receiving stand 304 when present) and presses it relatively weakly (assumes the first operating state shown by a solid line in Figures 12 and 13). When the electromagnetic solenoid 332 is actuated in the aforesaid state, the linking member 338 is moved downwardly against the force of the spring member 344, and abuts against the lower end of the elongate hole 336 to pivot the oscillating supporting member 314 clockwise in Figure 11 about the rotating shaft 312 as a center (at this time, the other oscillating supporting member 316 is also rotated). As a result, the delivery rollers 306 move away upwardly from the paper receiving stand 304 (form a copying paper on the receiving stand 304 when present) (assumes the inoperative state shown by a two-dot chain line in Figure 12). When the electromagnetic solenoid 334 is actuated in the aforesaid state, the linking member 338 is,moved upwardly against the force of the spring member 346 and abuts against the upper end of the elongate hole 336 to pivot the oscillating supporting member 314 counterclockwise in Figure 11 about the rotating shaft 312 as a center. At this time, the delivery roller 306 abuts against the upper surface of the paper receiving stand 304 (the upper surface of copying paper on the receiving stand 304 when present), and therefore, the force acting on the oscillating supporting member 314 via the linking member 338 by the action of the electromagnetic solenoid 334 is transmitted to the delivery rollers 306, and the delivery rollers 306 are pressed relatively strongly against the upper surface of the receiving stand 304 by the magnetic attracting force of the electromagnetic solenoid 334 which tends to attract the output terminal 342 electromagnetically (assume the state shown by a two-dot chain line in Figure 13). Now, with reference to Figures 12 and 13, the paper movement hampering means 310 will be described. The illustrated movement hampering means 310 has a plate-like movement hampering member 348 disposed on the forward end portion of the receiving stand 304. The lower end portion of the movement hampering member 348 is fixed to the output terminal 352 of an electromagnetic solenoid 350 disposed below the receiving stand 304. A spring member 354 is interposed between the electromagnetic solenoid 350 and the movement hampering member 348. The movement hampering member 348 is held at a hampering position (the position shown in Figures 12 and 13) at which its upper end portion projects upwardly through an opening 356 formed in the receiving stand 304 by the action of the spring member 354 when the electromagnetic solenoid 350 is inoperative, and at a receding position at which its upper end portion has receded from the upper surface of the receiving stand 304 when the electromagnetic solenoid 350 is actuated. In this modified embodiment, the electromagnetic solenoids 332, 334 and 350 are inoperative when a copying paper sheet having an image formed on one surface is received on the paper receiving stand 304. Therefore, the delivery rollers 306 are maintained at the aforesaid first operating state(the state shown by a solid line in Figures 12 and 13) and acts relatively weakly on the paper sheet received on the receiving stand 304. Furthermore, the movement hampering member 348 is held at the hampering position and the movement of the copying paper sheet is hampered upon abutment of its leading edge against the hampering member 348. The electromagnetic solenoid 332 is actuated (the electromagnetic solenoids 332 and 350 are inoperative) when the widthwise position of the paper sheet received on the receiving stand 304 is adjusted. As a result, the delivery rollers 306 are maintained in the inoperative state and move away upwardly from the paper sheet on the receiving stand 304. In delivering copying paper sheet received on the receiving stand 304, the electromagnetic solenoids 334 and 350 are actuated (at which time the electromagnetic solenoid 322 is inoperative). When the electromagnetic solenoid 350 is actuated, the movement hampering member 348 is held at the recedeing position, and the copying paper sheet on the receiving stand 304 is ready for delivery. When the electromagnetic solenoid 334 is actuated, the delivery rollers 306 are maintained in the second operating state and act relatively strongly on the copying paper sheet present on the receiving stand 304, and thus exactly deliver the paper sheet from the receiving stand 304 as they rotate in the direction shown by the arrow 330 (Figure 11). Accordingly, in this modified embodiment, too, substantially the same effect as in the embodiment shown in Figures 1 to 10 can be achieved. In the modified embodiment, there is used a preventing mechanism 362 comprised of a pair of rollers 358 and 360 in order to prevent feeding of copying paper sheets in the superposed state (Figures 12 and 13). The pair of rollers 358 and 360 are disposed downstream of the receiving stand 304 in the paper conveying direction. The roller 358 located above acts as a conveying roller which rotates in the conveying direction of the copying paper as shown by an arrow 364 and conveys it toward a paper conveying passage (not shown). The roller 360 below acts as a separating roller which rotates in a direction opposite to the paper conveying direction as shown by an arrow 366 and prevents feeding of two paper sheets at a time in the superposed state. The roller 360 is kept in contact with the roller 358 through an opening (not shown) formed in the receiving stand 304. It is critical that in the preventing mechanism 362, the roller 358 located above should have a larger coefficient of riction than the roller 360 located below. Preferably, the roller 358 is formed of, for example, rubber, and the roller 360, of rubber, sponge, etc. Other modified embodiments In the embodiment shown in Figures 1 to 10, the arrival of paper at the paper receiving stand 122 is detected by using the paper detecting mechanism 282 including follower roller 284 which rolls under the action of the moving paper and the detecting means 286 for detecting the rolling of the follower roller 284. Alternatively, the arrival of paper at the paper receiving stand can also be effectively detected by a mechanism shown in Figures 14 to 16 or Figure 17. With reference to Figures 14 to 16, mainly with reference to Figure 14 which shows the essential parts of the paper re-sending means, the illustrated paper re-sending means 402 is provided with a copying paper receiving stand 404 for receiving copying paper, a width matching means 406 for matching the widthwise positions of copying paper sheets received on the receiving stand 404, a delivery means disposed above the receiving stand 404, an actuating mechanism (not shown) for moving the delivery means in the desired manner, and a copying paper movement hampering means 410 for hampering the movement of copying paper. The paper receiving stand 404 is made up of a plate-like member, and the width matching means 406 is provided in the front part of the receiving stand 404. The illustrated width matching means 406 is composed of a pair of spaced movable matching members 412 and 414 which are mounted on the receiving stand 404 so that they can move in the forward-backward direction (vertically in Figure 14, and in the left-right direction in Figures 15 and 16), and therefore in the widthwise direction of the copying paper received on the receiving stand 404. Specifically, the movable matching member 412 and 414 are mounted for free movement between an outwardly located receiving position (the position shown by a solid line in Figures 14 to 16) and an inwardly located matching position (the position shown by a two-dot chain line in Figures 14 to 16), and constructed such that their receiving and matching positions are properly changed according to the size of the copying paper sheet received on the receiving stand 404. The movable matching members 412 and 414 respectively have base portions 412a and 414a contacting the upper surface of the receiving stand 404 and matching portions 412b and 414b extending upwardly substantially perpendicularly from the outside ends of the base portions 412a and 414a. In the modified embodiment, the matching portions 412b and 414b of the movable matching members 412 and 414 respectively extend rearwardly (to the left in Figure 14) from the forward ends of the base portions 412a and 414a beyond their rear ends as shown in Figures 14 and 15, and the rear end portion of the matching portion 414b of the movable matching member 414 is curved outwardly. The delivery means is comprised of a delivery roller 418 mounted on a supporting roller 416. As in the embodiment shown in Figures 1 to 10 or the modified embodiment shown in Figures 11 to 13, the delivery roller 418 is selectively maintained by the action of the actuating mechanism (not shown) in an inoperative state in which it is apart from the copying paper received on the receiving stand 404, a first operating state in which it acts relatively weakly on the copying paper received on the receiving stand 404 and a second operating state in which it acts relatively strongly on the copying paper received on the receiving stand 404. The movement hampering means 410 includes a pair of movement hampering members 420 and 422 spaced from each other in the forward-backward direction (the widthwise direction of the copying paper placed on the receiving stand 404) in the forward end of the receiving stand 404. The lower end portions of the movement hampering members 420 and 422 are fixed respectively to the output terminals of electromagnetic solenoids 424 and 426. The movement hampering members 420 and 422 are held at a hampering position at which their upper end portion projects upwardly from the upper surface of the receiving stand 404 by the action of a spring member (not shown) when the electromagnetic solenoids 424 and 426 are inoperative. When the electromagnetic solenoids 424 and 426 are actuated, these movement hampering members are held at a non-hampering position at which their upper ends have receded from the upper surface of the receiving stand 404. The copying paper re-sending means 402 further includes a copying paper detecting means 428. With reference to Figures 14 to 16, the illustrated copying paper detecting means 428 is comprised of a combination of a light emitting element 430 for projecting light and a light receiving element 432 for receiving light. It is critical that the paper detecting means 428 should be provided in the movable matching members movable between the receiving position and the matching position, and in the present modified embodiment, it is disposed in the movable matching member 414. As shown in Figures 15 and 16, the light emitting element 430 is fixed to the upper end of the matching portion 414b of the movable matching member 414, and the light receiving member 432 is fixed to the outside end of the base portion 414a of the movable matching member 414. Hence, the light emitting element 430 and the light receiving element 432 are vertically matched, so the light from the light emitting element 430 is adapted to be projected onto the light receiving element 432. Preferably, the paper detecting means 428 is disposed between the delivery roller 418 and the movement hampering means 410 as viewed in the paper conveying direction. More preferably, as shown in the modified embodiment, it is provided immediately before the movement hampering means 410 as viewed in the paper conveying direction (in the modified embodiment, the light emitting element 430 is fixed to the front end of the matching portion 414b and the light receiving element 432 is fixed to the front end of the base portion 414a as shown in Figures 14 and 15). Again with reference to Figure 14, a copying paper returning means defining a copying paper returning passage is provided upstream of the paper re-sending means 402 as viewed in the paper conveying direction. The paper returning means includes a deflecting-conveying means 436 disposed in the downstream end portion of the paper returning passage as viewed in the paper conveying direction. The illustrated deflecting-conveying means 436 is comprised of a pair of deflecting-conveying rollers 438 and 440. The deflecting-conveying roller 438 located below has a revolving shaft 442 to be revolved in the paper conveying direction and a plurality of axially spaced cylindrical rollers 444 mounted on the revolving shaft 442. The deflecting-conveying roller 440 located above have a rotatably mounted follower shaft 446 and a plurality of axially spaced rollers 448 mounted on the follower shaft 446 correspondingly to the rollers 444. The axes of the pair of deflecting-conveying rollers 438 and 440 are slightly inclined transversely toward the movable matching member 414 in which the paper detecting means 428 is provided. Specifically, the rotating shaft 442 (and therefore the rollers 444) and the follower shaft 446 (therefore the rollers 448) are slightly inclined transversely toward the movable matching member 414 so that as viewed in the paper conveying direction shown by an arrow 434, the forward end portions of the rotating shaft 442 and the follower shaft 446 are located more upstream than their rear end portions. The pair of deflecting-conveying rollers 438 and 440 nip the copying paper and convey it downstream toward the receiving stand 404, and may be used in place of the pair of returning rollers 118 used in the embodiment shown in Figures 1 to 10. A guide plate 450 is provided downstream of the pair of deflection-conveying rollers 438 and 440 as viewd in the paper conveying direction. The guide plate 450 corresponds to the guide plate 119 in the embodiment shown in Figures 1 to 10. The structures of the other parts of the electrostatic copying apparatus in the modified embodiment including the paper re-sending means 402 and the deflecting-conveying means 436 described above are substantially the same as in the electrostatic copying apparatus shown in Figures 1 to 10. In the electrostatic copying apparatus in this modified embodiment, a copying paper sheet having an image formed on one surface is conducted to the paper receiving stand 404 through the paper returning passage. While the copying paper sheet is conveyed by being nipped between the deflecting-conveying rollers 438 and 440, the copying paper sheet is deflected by the action of the deflecting-conveying rollers 438 and 440 in the direction of the arrow 434 (Figure 14), and therefore in a direction substantially perpendicular to the axes of the deflecting-conveying rollers 438 and 440 because the axes of these rollers 438 and 440 are slightly inclined transversely toward the movable matching member 414. The copying paper introduced into the receiving stand 404 via the upper surface of the guidge plate 450 by the action of the deflecting-conveying rollers 438 and 440 is conveyed downstream by the action of the delivery roller 418, and its movement is stopped when it abuts against the movement hampering members 420 and 422 held at the hampering position. When the copying paper is received on the receiving stand 404, the pair of movable matching members 412 and 414 are held at the receiving positions shown by solid lines in Figures 14 to 16, and therefore, the copying paper is accurately received on the receiving stand 404. It will be appreciated from Figure 16 that when the copying paper has been received as described above, one side edge of the copying paper (the upper side edge in Figure 14) abuts against the inside surface of the matching portion 412b of the movable matching member 414 held in the receiving position because the paper is deflected during passage as stated above. Thus, when the copying paper is moved and its leading end portion is conveyed to the movement hampering members 420 and 422, one side end part of the copying paper is positioned between the light emitting element 430 and the light receiving element 432 as can be seen from Figure 16. The light from the light emitting element 430 is shielded by this copying paper, and the paper detecting means 428 detects the fact that the copying paper has been received on the receiving stand 404 via the paper returning passage. When the paper has been so received, the movable matching members 412 and 414 are moved in the desired manner (at this time, the delivery roller 418 is kept in the inoperative state). Specifically, the movable matching members 412 and 414 are moved from the receiving positions to the matching positions shown by two-dot chain lines in Figures 14 to 16, and then to the receiving positions. When the movable matching members 412 and 414 are held at the matching positions, the inside surfaces of the matching portions 412 b and 414b act on both side edges of the copying paper on the receiving stand 404 to set the copying paper at a position shown by a two-dot chain line P₁ in Figure 14. When the matching members 412 and 414 are then held at the receiving positions, they recede from the copying paper, and the receiving stand 404 is ready for receiving the next copying paper. When the widthwise positioning of the copying paper has been terminated in this manner, no copying paper exists between the light emitting element 430 and the light receiving element 432 of the paper detecting means 428, and the paper detecting means 428 is ready for detecting the arrival of the next copying paper. In receiving a plurality of copying paper sheets on the papaer receiving stand 404, one sheet is received on the receiving stand 404 and then the next sheet is received in the stacked state on the preceding sheet. When the next sheet is conveyed likewise to the movement hampering members 420 and 422 by the action of the deflecting-conveying rollers 438 and 440, one side end portion of the next sheet is located between the light emitting element 430 and the light receiving element 432 as stated above, and the paper detecting means 428 detects the fact that the next sheet has been properly conveyed. Accordingly, in the electrostatic copying apparatus in the present modified embodiment, when the next copying paper P₃ is received on the copying paper P₂ present on the receiving stand 404 in the stacked state, the copying paper P₃ is deflected to the side of the movable matching member 414 by the action of the deflecting-conveying rollers 438 and 440, as shown in Figure 18. Hence, despite the fact that the copying paper sheets are received in the stacked state on the receiving stand 404, the arrival of copying paper can be exactly detected. It will be easily understood from Figures 14 and 16 that by providing the paper detecting means 428 in the movable matching member 414, it is also possible to detect whether the widthwise positioning of the copying paper has been carried out in the desired manner (in other words, when the widthwise positioning of the copying paper is not carried out in the desired manner, the paper detecting means 428 detects the copying paper also when it is moved from the matching position to the receiving position). In the modified embodiment shown in the drawings, the copying paper is adapted to be deflected rearwardly in the forward-backward direction by the action of the deflecting-conveying rollers 438 and 440. It is also possible to consturct the apparatus such that the copying paper is deflected forwardly in the forward-backward direction. This can be achieved by providing the paper detecting means 428 in the movable matching member 412 and incline the axes of the deflecting-conveying rollers 438 and 440 constituting the deflecting-conveying means by a predetermined angle in the direction of the movable matching member 412. Furthermore, in the modified embodiment, the cylindrical deflecting rollers 444 and 448 are used, and the axes of the deflecting-conveying rollers 438 and 440 are inclined in a predetermined direction. Alternatively, the deflecting-conveying rollers 438 and 440 may be made of rollers having a predetermined conical shape without inclining their axes (namely, by providing these rollers 438 and 440 such that their axes are substantially perpendicular to the paper conveying direction). In this case, the copying paper is moved while being deflected to the small-diameter portion of the conical rollers. In the modified embodiment shown in Figures 14 to 16, the deflecting-conveying means 436 is comprised of the pair of deflecting-conveying rollers 438 and 440. Alternatively, it may be made up of a single deflecting-conveying roller as shown in Figure 17. With reference to Figure 17, the deflecting-conveying means 436' shown in the drawing is comprised of a deflecting-conveying roller 452 disposed in the downstream end portion of the copying paper returning passage. It is to be noted that in Figure 17, the same parts as shown in Figures 14 to 16 are indicated by the same reference numerals. The deflecting-conveying roller 452 has a revolving shaft 456 to be revolved in the paper conveying direction shown by an arrow 454 and cylindrical deflecting rollers 458 mounted on the revolving shaft 456 at axially spaced intervals. The axis of the deflecting-conveying roller 452 is slightly inclined transversely toward the movable matching member 414 in which the paper detecting means 428 is provided as in the modified embodiment shown in Figures 14 to 16. Preferably, the deflection rollers 458 are formed of a relatively flexible material such as sponge. When the deflecting-conveying means 436' is constructed of the single deflecting-conveying roller 452, the copying paper is conveyed over the upper side of the deflecting-conveying roller 452, and preferably, as shown in Figure 19, a guide member 460 is provided over, and in relation to, the deflecting-conveying roller 452. More specifically, it is preferred that the upper portion of the deflection rollers 458 be in press contact with the under surface of the guide member 460 provided opposite to the deflection rollers 458. In this case, the copying paper is conveyed between the deflecting-conveying roller 452 and the guide member 460. When the deflecting-conveying means 436' is used, the copying paper is nipped between the deflection rollers 458 of the deflection-conveying roller 452 and the guide member 460 and moved toward the receiving stand 404 by the revolving of the deflection roller 458 in the direction shown by the arrow 454. During movement of the copying paper by the deflection rollers 458, the copying paper is moved downstream while being deflected rearwardly in the forward-backward direction under the action of the deflection rollers 458 since the axis of the deflecting-conveying roller 452, and therefore, the axes of the deflection rollers 458, are inclined in the direction of the movable matching member 414. Furthermore, since the deflection rollers 458 are pressed against the guide member 460, the copying paper is accurately moved by the cooperative action of the deflection rollers 458 and the guide member 460. Thus, in the case of using the deflecting-conveying means 436' described above, too, the same result as in the modified embodiment shown in Figures 14 to 16 is achieved. Incidentally, when the copying paper re-sending means 402 further includes a forwardly actuating roller for moving the copying paper toward the movement hampering members 420 and 422 (in which case a delivery roller for delivering the copying paper from the receiving stand 404 is separately provided above the receiving stand 404), it is possible to incline the axis of the forwardly actuating roller in a predetermined direction instead of inclining the deflecting-conveying roller. In this embodiment, the forwardly actuating roller acts as the deflecting-conveying means.

Claims: An electrostatic copying apparatus adapted to introduce a copying paper sheet having an image formed on one surface thereof during conveyance through a copying paper conveying passage (58) into a copying paper returning passage (110), return the copying paper sheet through the paper returning passage (110) to a copying paper resending means (120) disposed below the paper returning passage (110), and to feed it again to the paper conveying passage (58) from the re-sending means (120) in order to form an image on the other surface, said re-sending means (120) including a copying paper receiving stand (122) for receiving copying paper sheets having an image formed on one surface in the stacked state, a width matching means (146) for matching the widthwise positions of the copying paper sheets received on the paper receiving stand (122), and a delivery means (126) disposed above the paper receiving stand (122); characterized in that said paper re-sending means (120) further includes an actuating mechanism (152) for maintaining said delivery means (126) selectively in a non-operating state in which it is kept apart from a copying paper sheet received on the paper receiving stand (122), in a first operating state in which it acts relatively weakly on said copying paper sheet, and in a second operating state in which it acts relatively strongly on said copying paper sheet, and said actuating mechanism (152) maintains the delivery means (126) in the first operating state when the copying paper sheet having an image formed on one surface is received on the paper receiving stand (122) through the returning passage (110), in the non-operating state when the widthwise positions of the copying paper sheets received on the receiving stand (122) are matched by the action of the width matching means (146), and in the second operating state when the copying paper sheet received on the paper receiving stand (122) is delivered toward the paper conveying passage (58). The apparatus of claim 1 wherein the actuating mechanism (152) includes a first and a second actuating means (202, 204), and maintains the delivery means (126) in the first operating state when both the first and second actuating means are in the non-operating state, in the non-operating state when the first actuating means (202) is in the operating state and the second actuating means (204) is in the non-operating state, and in the second operating state when the first actuating means (202) is in the non-operating state and the second actuating means (204) is in the operating state. The apparatus of claim 2 wherein the actuating mechanism (152) includes an oscillably mounted oscillating supporting member (162, Fig. 7) having an elongate hole (196) formed at its rear end portion with a linking member (194) being inserted into the elongate hole movably there-along; the first and second actuating means are composed of electromagnetic solenoids (202, 204) the output terminals of which are connected to the linking member; and the delivery means is composed of a delivery roller (126) mounted on the forward end portion of the oscillating supporting member (162) for rotation in a predetermined direction. The apparatus of claim 3 wherein when the first and second actuating means (202, 204) are both in the non-operating state, the linking member (194) is located in the middle of the elongated hole of the oscillating supporting member (162) and thus the delivery roller (126) acts on the copying paper sheet received in the paper receiving stand (122) by its own weight and presses it relatively weakly; when the first actuating means (202) is in the operating state and the second actuating means (204) is in the non-operating state, the linking member abuts against one end of the elongate hole and acts on the oscillating supporting member (162), and thus the delivery roller (126) moves upwardly away from the copying paper sheet on the paper receiving stand (122) by the action of the first actuating means (202); and when the first actuating means (202) is in the non-operating state and the second actuating means (204) is in the operating state, the linking member abuts against the other end of the elongate hole and acts on the oscillating supporting member (162) and thus the delivery roller acts on, and relatively strongly presses, the copying paper sheet on the paper receiving stand (122) by the action of the second actuating means (204). The apparatus of claim 1 wherein the paper re-sending means further includes means (302) for preventing feeding of copying paper sheets in the superposed state, and the preventing means (302) is comprised of a pair of rollers (358, 360) disposed downstream of the paper receiving stand (304) in the paper conveying direction; and one (358) of the pair of rollers is rotated in the paper conveying direction and acts as a conveying roller and the other (360) is rotated in a direction opposite to the paper conveying direction and acts as a separation roller. The apparatus of claim 1 wherein the paper re-sending means (120) includes a copying paper movement hampering means (124) disposed on the forward end portion of the paper receiving stand (122), and the movement hampering means (124) is selectively held at a hampering position at which it acts on the copying paper sheet received on the paper receiving stand (122) and a receding position at which it has receded from the copying paper sheet received on the paper receiving stand (122). The apparatus of claim 6 wherein the actuating mechanism moves the delivery means and the movement hampering means (124); the actuating mechanism maintains the delivery means in the first operating state, and holds the movement hampering means (124) at the hampering position, when a copying paper sheet having an image formed on one surface is received on the paper receiving stand (122) via the paper returning passage; the actuating mechanism holds the movement hampering means (124) at the hampering position and maintains the delivery means in the non-operating state when the widthwise position of the copying paper sheet received on the paper receiving stand is adjusted by the action of the width matching means; and the actuating mechanism maintains the delivery means in the second operating state and holds the movement hampering means (124) at the receding position when the copying paper sheet received on the paper receiving stand (122) is delivered toward the copying paper conveying passage (58). The apparatus according to claim 6 or 7 wherein the actuating mechanism includes a first and second actuating means; the actuating mechanism maintains the delivery means in the first operating state and holds the movement hampering means (124) at the hampering position when the first and second actuating means are both in the non-operating state; the actuating mechanism maintains the delivery means (126) in the non-operating state and holds the movement hampering means (124) at the hampering position when the first actuating means is in the operating state and the second actuating means is in the non-operating state, and the actuating mechanism maintains the delivery means in the second operating state and holds the movement hampering means (124) at the receding position when the first actuating means is in the non-operating state and the second actuating means is in the operating state. The apparatus of claim 8 wherein the actuating mechanism includes a first (162), a second (164) and a third (166) oscillating member mounted oscillably, the delivery means is rotatably mounted on the first oscillating member (162), and the movement hampering means (124) is mounted on the third oscillating member (166); when the first and second actuating means (202, 204) are in the non-operating state, the first oscillating member (162) is oscillable and thus the delivery roller acts by its own weight on the copying paper sheet received on the paper receiving stand (122) and presses it relatively weakly; when the first actuating means (202) is actuated, the first oscillating member (162) is pivoted in a predetermined direction and thus the delivery means moves away from the copying paper sheet received on the paper receiving stand (122) and is situated above it; and when the second actuating means (204) is actuated, the third oscillating member is pivoted and the first os- cillating member (162) is pivoted in a direction opposite to said predetermined direction incident to the pivoting movement of the third oscillating member (166) transmitted through the second oscillating member (164), whereby the movement hampering means (124) is moved from the hampering position to the receding position and held there and the delivery means is maintained in the second operating state. The apparatus of claim 9 wherein a spring member (188) is interposed between the first oscillating member (162) and the second oscillating member (164), and when the second actuating means is actuated, the first oscillating member (162) is pivoted in a direction opposite to said predetermined direction incident to the pivoting movement of the third oscillating member transmitted through the second oscillating member (164) and the spring member, whereby the delivery means elastically acts on, and relatively strongly presses, the copying paper sheet on the paper receiving stand (122) by the action of the spring member. The apparatus of claim 9 wherein the actuating mechanism further includes a pivotably mounted revolving lever (210) one end portion of which is connected to the first actuating means (202), and the first oscillating member (162) has an abutment portion (226) against which the other end portion of the revolving lever (210) can abut; and when the first actuating means is actuated, the revolving lever (210) is pivoted and the other end portion of the revolving lever (210) acts on the abutment portion to pivot the first oscillating member in said predetermined direction whereby the delivery means moves away from, and is situated above, the sheet-like copying paper received on the paper receiving stand (122). The apparatus of claim 9 wherein the second actuating means (204) is connected to the third oscillating member (166) and the second oscillating member (164) has an abutment portion (200) against which a part of the third oscillating member (166) can abut; and when the second actuating means (204) is actuated, the third oscillating member (166) is pivoted and said part of the third oscillating member (166) acts on the abutment portion (200) of the second oscillating member (164) whereby the second oscillating member (164) is pivoted incident to the pivoting movement of the third oscillating member (166). The apparatus of claim 9 wherein a mechanism for preventing feeding of copying papers in the superposed state is disposed downstream of the paper re-sending means (120) as viewed in the paper conveying direction in relation to the paper re-sending means (120), and the preventing mechanism (178) includes a conveying roller (132) adapted to be revolved in a predetermined direction and a frictional member, and the frictional member (246) is selectively maintained in an operating state at which it acts on the conveying roller (132) and a non-operating state in which it is set apart from the conveying roller (132). The apparatus of claim 13 wherein the mechanism (178) for preventing feeding of papers in the superposed state includes an oscillating arm (266) oscillably mounted and adapted to pivot in relation to the pivoting movement of the third oscillating member (166), the frictional member (246) is mounted on the oscillating arm (266), and the frictional member (246) is maintained in the non-operating state when the second actuating means is non-operating, and is maintained in the operating state in relation to the pivoting movement of the third oscillating member (166) when the second actuating means is actuated. The apparatus of claim 14 wherein a pressing spring member (278) is interposed between the oscillating arm (266) and the frictional member (246), and in said operating state, the frictional member (246) is elastically held in press contact with the peripheral surface of the conveying roller (132). The apparatus of claim 15 wherein a supporting member (270) is mounted on the oscillating arm (266) so that it can move over a predetermined range toward and away from the conveying roller (132), said pressing spring member is also interposed between the oscillating arm (266) and the supporting member (270), and the frictional member is mounted on the supporting member. The apparatus of claim 8 wherein the first and second actuating means are comprised of electromagnetic solenoids (202, 204). The apparatus of claim 7 wherein the movement hampering means (124) is free to pivot between the hampering position and the receding position, and projects upwardly from the upper surface of the paper receiving stand (122) when it is at the hampering position, and is away from the upper surface of the paper receiving stand (122) when it is at the receding position. An electrostatic copying apparatus adapted to introduce a copying paper sheet having an image formed on one surface thereof during conveyance through a copying paper conveying passage (58) into a copying paper returning passage (110), return the copying paper sheet through the paper returning passage (110) to a copying paper resending means (120) disposed below the paper returning passage, and to feed it again to the paper conveying passage (58) from the re-sending means (120) in order to form an image on the other surface, said re-sending means (120) including a copying paper receiving stand (122) for receiving copying paper sheets having an image formed on one surface in the stacked state, characterized in that said apparatus further includes a copying paper detecting mechanism (282) comprising a supporting member (168, Fig. 8) disposed vertically movable above the copying paper receiving stand (122), a follower roller (284) mounted rotatably on the supporting member (168) and adapted to roll under the action of a paper sheet received on the paper receiving stand (122), and a detecting means (286) for detecting the rolling of the follower roller (284). The apparatus of claim 19 wherein an additional roller (126) for conducting the paper sheet to the paper receiving stand (122) is provided mechanically linked to the follower roller (284), and the additional roller (126) is mounted rotatably on the supporting member (168) and adapted to rotate in a predetermined direction. The apparatus of claim 20 wherein the roller is a delivery roller (126) for delivering a copying paper sheet received on the paper receiving stand (122) toward the paper conveying passage (58). The apparatus of claim 19 wherein the detecting means (286) is comprised of a combination of a light emitting element (290) and a light receiving element (292) disposed on opposite sides of the follower roller (284), and the follower roller (284) has formed therein an opening through which the light from the light emitting element can pass. An electrostatic copying apparatus comprising a copying paper conveying means defining a copying paper conveying passage (58), a copying paper feeding means for feeding a copying paper sheet to the paper conveying passage (58), a copying paper returning means defining a copying paper returning passage (110), a copying paper refeeding means defining a copying paper re-feeding passage (128), and a copying paper re-sending means (120) for receiving a copying paper sheet returned through the paper returning passage (110) and re-sending it to the paper conveying passage (58) through the paper re-feeding passage, said apparatus being adapted to feed a copying paper sheet to the paper conveying passage (58) from the paper feeding means, convey it through the paper conveying passage (58) to form an image on one surface of the sheet during conveyance through the conveying passage (58), and adapted to introduce the copying paper sheet having an image formed on one surface into the paper returning passage (110), return the copying paper sheet through the paper returning passage to the paper re-sending means (120), re-feed the copying paper sheet through the paper re-feeding passage (128) from the paper re-sending means to the paper conveying passage, and re-conveying the copying paper sheet through the paper conveying passage to form an image on its other surface during the re-conveyance; wherein the paper re-sending means (120) includes a copying paper receiving stand (122) for receiving in the stacked state copying paper sheets returned through the paper returning passage, a width matching means (406, Fig. 14) for matching the widthwise positions of the copying paper sheets received on the paper receiving stand (122), the width matching means (406) includes at least one movable matching member (412, 414) movable between a receiving position at which the copying papers are received and a matching position at which the widthwise positions of the copying paper sheets are matched, characterized by a copying paper detecting means (428) for detecting a copying paper sheet in the receiving position of the movable matching member, said copying paper detecting means (428) being mounted on the movable matching member (414), and in that the paper returning means further includes a deflecting-conveying means (436) for conveying in the deflected state the copying paper sheet, which is to be returned toward the paper re-sending means (120), toward the movable matching member (414) on which the paper detecting means is mounted. The apparatus of claim 23 wherein the width matching means has a pair of movable matching members (150, 412, 414) spaced from each other, and each of the pair of movable matching members is free to move in the widthwise direction of the copying paper sheet received on the paper receiving stand (122) between the receiving position and the matching position. The apparatus of claim 23 wherein the deflecting-conveying means is comprised of a pair of deflecting-conveying rollers (438, 440) disposed in the downstream end portion of the paper returning passage in the paper conveying direction; the axis of each of the pair of deflecting-conveying roller is inclined transversely toward the movable matching member (414) on which the paper detecting means (428) is mounted; and the copying paper sheet returned toward the paper re-sending means (120) through the paper returning passage is nipped between the pair of deflecting-conveying rollers and conveyed by the action of the pair of deflecting-conveying rollers while being deflected toward the movable matching member (414) on which the paper detecting means (428) is mounted. The apparatus of claim 23 wherein the deflecting-conveying means is comprised of a deflecting-conveying roller (452) disposed in the downstream end portion of the paper returning passage (110) in the paper conveying direction; the axis of the deflecting-conveying roller is inclined transversely toward the movable matching member (414) on which the paper detecting means (428) is mounted; and the copying paper sheet returned toward the paper resending means (120) through the paper returning passage is conveyed over the deflecting-conveying roller and under the action of the deflecting-conveying roller, deflected toward the movable matching member (414) on which the paper detecting means (428) is mounted during conveyance.

Inventors: KAJITA, HIROSHI, UEHARA, YOSHIYUKI RM. 205 SHIRAKABA-SO, UJINO, KOJI
Applicants: MITA INDUSTRIAL CO. LTD.
Application year: 1985
Main classification: G03G15
IPC codes: G03G15