JP3651565B2 - Paper reversing device for image forming machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a paper reversing device for an image forming machine such as a laser beam printer or an electrostatic copying machine. Relates to the device.
[0002]
[Prior art]
In this type of image forming machine, generally only one image forming unit for forming an image is provided. Therefore, in order to form an image on both sides of a sheet, it is necessary to reverse the sheet on which the image is formed on one side and convey it again to the image forming unit. For this reason, an image forming machine capable of forming images on both sides of a sheet is equipped with a sheet reversing device for inverting the sheet on which the image is formed on one side.
[0003]
As a sheet reversing device of an image forming machine, a so-called switchback method is generally used in which a sheet on which an image is formed on one side is once transported to a reversing path and then transported to the double-sided paper feeding unit with the front and back of the sheet reversed. Yes. However, the switchback method has to temporarily store the paper in the reversing path, and therefore requires a reversing path having a length corresponding to the maximum size of the usable paper, which requires a large space.
[0004]
A paper reversing device for an image forming machine that solves the problems of the switchback method described above is disclosed in Japanese Patent Laid-Open No. 5-92858. The paper reversing device of an image forming machine disclosed in this publication includes a rotating body having a clamping means on an outer peripheral surface and a driving means for driving the rotating body to rotate forward and reversely, and an image is formed on one side. The paper is wound around the rotating body by rotating the rotating body forward while being gripped by the front edge of the sheet and the clamping means, and the rotating body is driven reversely after winding. It is designed to be transported to the paper section.
[0005]
[Problems to be solved by the invention]
The sheet conveyed to the sheet reversing device of each image forming machine described above is so-called curled due to heating and pressurization by passing through a fixing device for heating and fixing an image formed on one side. When the paper curls in this way, it may cause a paper jam (jam) during conveyance. Therefore, it is desirable that the curl removal be performed when the sheet having an image formed on one side is reversed by the sheet reversing device and conveyed to the duplex feeding unit. As a countermeasure for removing the curl of the paper, a method of curving in a wave shape when the paper passes through the conveyance path is generally used.
[0006]
The present invention has been made in view of the above-described facts, and its main technical problem is to be able to reverse the paper in a small space and to remove the curl generated on the paper when passing through the fixing device. An object of the present invention is to provide a sheet reversing device for an image forming machine.
[0007]
[Means for Solving the Problems]
In order to solve the above main technical problem, according to the present invention, in a sheet reversing device of an image forming machine that reverses and conveys a sheet on which an image is formed on one side,
A paper carry-in path for carrying paper with an image formed on one side;
The rotary shaft, at least two types of disc-shaped members having different diameters arranged at intervals in the axial direction on the rotary shaft, and the outer peripheral surface of one of the two types of disc-shaped members are conveyed. A paper take-up mechanism for taking up the paper carried into the paper carry-in path,
A rotational drive mechanism having a drive roller disposed in contact with the outer peripheral surface of the other disk-shaped member of the two types of disk-shaped members, and a drive source for driving the drive roller to rotate forward and reversely;
A paper discharge path for discharging the paper that has been rewound after being taken up by the paper take-up mechanism,
A sheet reversing device for an image forming machine is provided.
[0008]
The locking means is disposed to face one disk-shaped member having a small diameter of the two types of disk-shaped members, and the drive roller is disposed to face the other disk-shaped member having a large diameter. It is also desirable that a friction member having a large friction coefficient is mounted on the outer peripheral surface of the other disk-shaped member of the two types of disk-shaped members.
[0009]
The locking means includes a locking roller for sandwiching the leading edge of the paper between the outer peripheral surface of the other disk-shaped member, and this locking roller is preferably formed of an elastic member. The locking means includes contact means for contacting the leading edge of the paper. The contact means is provided on an arm having one end attached to the rotating shaft via a one-way clutch. The locking roller is mounted on the other end of the arm.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a sheet reversing device of an image forming machine configured according to the present invention will be described with reference to the accompanying drawings.
[0011]
FIG. 1 is a schematic cross-sectional view of a laser beam printer as an image forming machine equipped with a paper reversing device constructed according to the present invention.
The illustrated laser beam printer includes an image forming machine main body 100 and a reversal paper feeding unit 200 that can be optionally attached to the image forming machine main body 100. The image forming machine main body 100 includes a rectangular parallelepiped housing 101 made of synthetic resin. In the substantially central portion of the housing 101, there is a space between a front side plate and a rear side plate made of a metal plate (not shown) arranged at a predetermined interval in the front-rear direction (a direction perpendicular to the paper surface in FIG. 1) in the housing 101. A photosensitive drum 104 is rotatably disposed. The photosensitive drum 104 is rotationally driven by a gear transmission (not shown) through a charging area, an electrostatic latent image forming area, a developing area, a transfer area, and a cleaning area in the direction indicated by an arrow 105 in order. Around the photosensitive drum 104, a charging corona discharge device 106 is disposed in a charging area, a developing device 108 is disposed in a developing area, a transfer roller 110 serving as a transferring apparatus is disposed in a transferring area, and a cleaning device 112 is disposed in a cleaning area. Yes.
[0012]
The charging corona discharger 106 charges the photosensitive layer mounted on the peripheral surface of the photosensitive drum 104 to a specific polarity. In the illustrated embodiment, the developing device 108 includes a developing roller and an agitating unit disposed in a developing housing that contains a developer composed of one-component toner. The electrostatic latent image formed on the surface is developed into a toner image. A toner cartridge 114 containing replenishing toner is detachably mounted above the developing device 108, and is replenished sequentially when a predetermined amount of toner in the developing device 108 is consumed. The transfer roller 110 is made of, for example, conductive foamed urethane, is rotatably supported by the front and rear side plates, and is driven to rotate in a direction indicated by an arrow by a gear transmission (not shown). For example, a constant current of about 10 μA is applied to the transfer roller 10. The cleaning device 112 includes a cleaning fur brush, a cleaning blade, and the like, and removes toner remaining on the peripheral surface of the photosensitive drum 104.
[0013]
A laser unit 116 as an electrostatic latent image forming apparatus is disposed in the upper part of the housing 102, that is, above the photosensitive drum 104. The laser unit 116 projects, for example, laser light based on image information output from a computer onto the peripheral surface of the photosensitive drum 104 in the electrostatic latent image forming area.
[0014]
In the housing 101, there is provided a sheet conveyance path 120 formed through the transfer area from the right side to the upper left side in the drawing. A paper feed roller pair 122 and a registration roller pair 124 are disposed upstream of the transfer area in the paper transport path 120. Further, a fixing roller pair 126, a conveying roller pair 128, a branching claw 130, and a discharge roller pair 132 constituting a fixing device are disposed on the downstream side of the transfer area in the sheet conveying path 120. The branch claw 130 is configured to be operable at a first position indicated by a solid line and a second position indicated by a two-dot chain line in FIG. 1 and is operated by an electromagnetic solenoid (not shown). When the branching claw 130 is positioned at the first position indicated by the solid line, the sheet conveyed by the conveying roller pair 128 is sent toward the discharge roller pair 132, and the branching claw 130 is indicated by the second dotted line indicated by the two-dot chain line. When positioned, the sheet conveyed by the conveying roller pair 128 is sent toward the duplex image forming discharge port 102.
[0015]
A cassette housing portion is provided below the paper transport path 120, and a paper cassette 134 is detachably attached to the cassette housing portion. The paper stored in the paper cassette 134 is fed toward the paper feed roller pair 122 by a feed roller 136 and a separating roller pair 138. Note that a sheet insertion path 135 is provided at the right end of the sheet cassette 134 in the figure, and is opened facing the sheet feeding roller pair 122 when mounted on the housing 101. A lower part of the housing 101, that is, a lower side of the cassette housing portion, accommodates a control unit 400 and the like, which will be described later, for controlling the operation of the components of the image forming machine main body 100 and the components of the reversal paper feeding unit 200 which will be described later. The apparatus accommodating part 140 is provided. A sheet insertion path 141 that communicates with the sheet insertion path 135 provided in the sheet cassette 134 is provided at the right end of the device accommodating portion 140 in the drawing.
[0016]
The image forming machine main body 100 in the illustrated embodiment is configured as described above, and the operation thereof will be described below.
While the photosensitive drum 104 is rotated in the direction indicated by the arrow 105, the charging corona discharger 106 charges the photosensitive layer of the photosensitive drum 104 to a specific polarity. Next, from a laser light source (not shown) of the laser unit 116 in an electrostatic latent image forming area between the charging area where the charging corona discharger 106 is arranged and the developing area where the developing device 108 is arranged. Laser light is projected onto the photosensitive drum 104, and an electrostatic latent image corresponding to image information is formed on the peripheral surface of the photosensitive drum 104. Thereafter, the developing roller of the developing device 108 causes the toner to act on the electrostatic latent image on the photosensitive drum 104 to develop the electrostatic latent image into a toner image. On the other hand, the paper fed from the recording paper cassette 134 by the feed roller 136 and the separating roller pair 138 is transported by the paper feed roller pair 122 and temporarily stopped by the registration roller pair 124, and takes time with the photosensitive drum 104. The photosensitive drum 104 and the transfer roller 110 are conveyed to a transfer area facing each other. A toner image formed on the peripheral surface of the photosensitive drum 104 by the action of the transfer roller 110 is transferred to the surface of the sheet conveyed to the transfer area.
[0017]
The sheet onto which the toner image has been transferred is peeled off from the photosensitive drum 104 and then conveyed to the fixing roller pair 126, and the toner image is heated and fixed on the surface of the sheet by the action of the fixing roller pair 126. The sheet on which the toner image is fixed is discharged to the receiving portion 103 formed on the housing 101 via the transport roller pair 128 and the discharge roller pair 132. When images are formed on both sides of the paper, the branching claw 130 is positioned at the second position indicated by a two-dot chain line in FIG. 1, and thus the toner image is fixed by the action of the fixing roller pair 126. The sheet is fed toward the duplex image forming discharge port 102 through the conveyance roller pair 128. On the other hand, the photosensitive drum 104 continues to rotate, and residual toner is removed from the surface of the photosensitive drum 104 by the action of the cleaning device 112.
[0018]
Next, the reverse paper feeding unit 200 will be described.
The reversing paper feeding unit 200 in the illustrated embodiment includes a paper reversing unit 210, a double-sided paper feeding unit 280, and a stacking tray 290. The paper reversing unit 210 is mounted on the left end portion of the double-sided paper feeding unit 280 in FIG. The stacking tray 290 is disposed on the upper surface of the sheet reversing unit 210. Then, the image forming machine main body 100 is placed on the upper right side of the sheet reversing unit 210 in the duplex feeding unit 280 in FIG.
[0019]
A paper reversing unit 210 constituting the reversing paper feeding unit 200 will be described with reference to FIGS.
A paper reversing unit 210 as a paper reversing device of the image forming machine includes a unit housing 212. In the unit housing 212, an arc-shaped paper carry-in path 216 having a paper inlet 214 is provided at a position facing the double-sided image forming discharge port 102 of the image forming machine main body 100. The sheet carry-in path 216 is opposed to the plurality of ribs 218 provided on the inner surface of the unit housing 212 at intervals in the front-rear direction (the direction perpendicular to the sheet surface in FIG. 2). It is formed by a plurality of ribs 220 arranged at intervals in the front-rear direction (the direction perpendicular to the paper surface in FIG. 2), and is configured over an angle of about 180 degrees. Conveying roller pairs 222 and 224 are disposed in the paper carry-in path 216. The conveyance roller pairs 222 and 224 are rotationally driven in a direction indicated by an arrow in FIG. 2 through a power transmission mechanism (not shown) by a driving force of the electric motor 225 (M1). A branch claw 227 is disposed between the conveyance roller pair 222 and the conveyance roller pair 224 in the paper carry-in path 216. The branch claw 227 is configured to be operable at a first position indicated by a solid line and a second position indicated by a two-dot chain line in FIG. 2, and is operated by an electromagnetic solenoid 228 (SOL1). . The electromagnetic solenoid 228 (SOL1) positions the branching claw 227 at the first position when being deenergized, and positions the branching claw 227 at the second position when being energized. When the branching claw 227 is positioned at the first position indicated by the solid line, the sheet conveyed by the conveying roller pair 222 is disposed on the unit housing 212 through the discharge port 213 provided on the upper wall of the unit housing 212. Is discharged to the stacking tray 290. On the other hand, when the branching claw 227 is positioned at the second position indicated by the two-dot chain line, the sheet conveyed by the conveying roller pair 222 is sent toward the conveying roller pair 224.
[0020]
A paper take-up mechanism 230 is disposed inside the paper carry-in path 216 in the unit housing 212. The sheet take-up mechanism 230 in the illustrated embodiment has a rotating shaft 232 that is rotatably arranged as shown in FIG. 3 and a diameter 2 that is arranged on the rotating shaft 232 at an interval in the axial direction. There are disc-shaped members 233 and 235 of different types. Two disk-shaped members 233 having a large diameter are disposed on both sides, and two disk-shaped members 235 having a small diameter are disposed between the two disk-shaped members 233. In the illustrated embodiment, a friction member 234 having a large friction coefficient such as urethane rubber is mounted on the outer peripheral surface of the two disk-shaped members 233 having a large diameter. The paper take-up mechanism 230 in the illustrated embodiment includes a locking unit 240 that locks the leading end of the paper conveyed to the outer peripheral surface of the two disk-shaped members 233 having a small diameter. The locking means 240 includes a pair of arms 241 and 241 disposed on the outer sides of the two disk-like members 235, respectively. The pair of arms 241 and 241 are formed with bent middle portions, and these bent portions function as a paper contact portion 242 as a paper contact means. One end of each of the pair of arms 241 and 241 is attached to the rotating shaft 234 via a one-way clutch 243 of a coil spring type. The one-way clutch 243 does not drive the arm 241 when the rotating shaft 232 rotates in the forward direction indicated by 232a in FIG. 2, and when the rotating shaft 232 rotates in the forward direction indicated by 232b in FIG. It functions to drive the arm 241. A support shaft 244 is mounted on the other end of each of the pair of arms 241 and 241, and two locking rollers 245 and 245 are rotatably mounted on the support shaft 244. The locking rollers 245 and 245 are formed of an elastic member such as urethane foam, and the outer peripheral surfaces thereof are lightly pressed against the outer peripheral surfaces of the disk-shaped members 235 and 235, respectively. The leading edge of the sheet conveyed is sandwiched between the sheet and the surface.
[0021]
The sheet reversing unit 210 in the illustrated embodiment includes a rotation driving mechanism 250 for appropriately rotating the sheet winding mechanism 230 as shown in FIG. The rotation drive mechanism 250 is a position corresponding to the drive shaft 252 disposed parallel to the rotation shaft 232 of the paper take-up mechanism 230 and the two disk-shaped members 233 and 233 having a large diameter on the drive shaft 252. And two drive rollers 253 made of urethane rubber or the like, and the two drive rollers 233 and 253 are in pressure contact with the friction member 234 mounted on the outer peripheral surface of the two disk-like members 233. Has been. Therefore, when the two drive rollers 253 and 253 rotate, the two disk-like members 233 and 233 having large diameters frictionally engaged with the two drive rollers 233 and 233 are rotated and the paper take-up mechanism 230 is rotated. A gear 254 is attached to one end of the drive shaft 252, and a drive gear 257 attached to a drive shaft of an electric motor 256 (M 2) as a drive source is meshed with the gear 254. The electric motor 256 (M2) is configured to be able to rotate forward and reverse. In the illustrated embodiment, the two disk-shaped members 233 and 233 having a large diameter are driven by the driving rollers 253 and 253 so as to face the outer peripheral surface of the two disk-shaped members 235 having a small diameter. Since the locking means 240 is provided, the radial dimension of the paper take-up mechanism 230 can be reduced.
[0022]
In the illustrated embodiment, the sheet reversing unit 210 is configured such that the front end of the center of the sheet transported by the transport roller pair 224 is a nip between the disk-shaped member 235 of the sheet take-up mechanism 230 and the locking roller 245 of the locking means 240. Guide means 260 is provided for guiding toward the part. As shown in FIG. 4, the guide means 260 includes a pair of support members 262 and 262 that are rotatably supported by the drive shaft 252 of the rotational drive mechanism 240, and a pair of support members 262 and 262. And a guide claw 263 provided on the front side in the paper winding direction and a rib 221 provided on one end of the pair of support members 262 and 262 in the paper winding direction rear end and the other end provided on the unit housing 212. The coil spring 264 is locked. Further, a pair of holding members 265 and 265 for holding the locking means 240 at the standby position shown in FIG. 2 are attached to the pair of support members 262 and 262. An engaging portion 266 that engages a support shaft 244 attached to the other end of the pair of arms 241 and 241 of the locking means 240 is formed at the tip of the holding member 265. The pair of support members 262 and 262, the guide claws 263, and the pair of holding members 265 and 265 are integrally formed of an appropriate synthetic resin, and the coil spring 264 balances them in the state shown in FIG. The spring force is set. In this state, the support shaft 244 of the locking means 240 is engaged with the engaging portion 266 of the holding member 265 so as to be held at the standby position.
[0023]
At the paper exit 217 side of the paper carry-in path 216, the paper discharged from the paper carry-in path 216 is guided toward the paper take-up mechanism 230, and the paper taken up by the paper take-up mechanism 230 is discharged. A guide claw 272 for guiding toward the path 270 is provided. The guide claw 272 is rotatably supported on the rib 218 by a support pin 273. One end of a coil spring 274 is locked to the guide claw 272, and the other end of the coil spring 274 is locked to a rib 218. The coil spring 274 is set to a spring force that balances the guide claw 272 in the state shown in FIG. Accordingly, when the paper is ejected from the paper exit 217 of the paper carry-in path 216 in the state shown in FIG. 2, the guide claw 272 is rotated clockwise in the drawing around the support pin 273 by the paper transport force to feed the paper. When the sheet is guided toward the sheet take-up mechanism 230 and the sheet passes, the coil spring 274 returns to the state shown in FIG. The guide claw 272 guides the paper taken up by the paper take-up mechanism 230 toward the paper discharge path 270 in the state shown in FIG. 2 that balances with the spring force of the coil spring 274.
[0024]
The sheet reversing unit 210 configured as described above is provided with a sheet detection switch 275 (SW1) for detecting a sheet carried into the sheet inlet 214 portion of the sheet carry-in path 216, and the guide claw 272 includes A paper detection switch 276 (SW2) for detecting the paper discharged from the paper carry-in path 216 is disposed at the opposed position. Further, a paper detection switch 277 for detecting that the paper taken up by the paper take-up mechanism 230 is also sent out from the nip portion in the vicinity of the nip portion between the drive roller 253 and the disk-shaped member 233 having a large diameter. (SW3) is provided. These paper detection switches 275 (SW1), 276 (SW2) and 277 (SW3) send an ON signal to the control means 400 described later when the paper is passing and an OFF signal when the paper is not passing, respectively. To do. In the illustrated embodiment, an example in which micro switches are used as the paper detection switches 275 (SW1), 276 (SW2), and 277 (SW3) is shown, but a photo interrupter may be used. When a photo interrupter is used, a light shielding plate may be used alone or a mechanism that interlocks with each guide means or guide claw, and reliable detection can be performed with a simple mechanism.
[0025]
Next, the double-sided paper feeding unit 280 constituting the reverse paper feeding unit 200 will be described with reference to FIG.
The double-sided paper feeding unit 280 constituting the double-sided paper feeding unit includes a unit housing 282. In the unit housing 282, a paper conveyance path 283 is formed that communicates the paper discharge path 270 of the paper reversing unit 210 and the paper insertion path 141 provided in the device accommodating portion 140. In the paper conveyance path 283, conveyance roller pairs 284, 285, and 286 are disposed. These transport roller pairs 284, 285, and 286 are rotationally driven in a direction indicated by an arrow by an electric motor (not shown), and a sheet insertion path 141 provided in the device accommodating portion 140 for feeding a sheet sent from the sheet reversing unit 210. The paper is conveyed toward the paper feed roller pair 122 through a paper insertion path 135 provided in the paper cassette 134. Note that a sheet insertion path 287 communicating with the sheet insertion path 141 provided in the device accommodating portion 140 is provided at the right end portion of the unit housing 282 in the drawing. The sheet insertion path 287 functions as a conveyance path for sheets fed from the sheet cassette when another sheet cassette is disposed below the duplex feeding unit 280.
[0026]
Here, the operation of the sheet reversing unit 210 will be described with reference to FIGS.
When an image is formed on the other side of the paper P on which an image is formed on one side by the image forming machine main body 100, the branching claw 227 is positioned at the second position shown in FIG. When the paper P on which an image is formed on one side is carried in from the paper inlet 214 of the paper carry-in path 216, the paper P is transported along the paper carry-in path 216 by the pair of transport rollers 222 and 224, and is fed from the paper outlet 217. It is discharged toward the winding mechanism 230. At this time, the guide claw 272 is rotated clockwise in FIG. 5 against the spring force of the coil spring 274 around the support pin 273 by the conveyance force of the paper P, and the paper P is directed toward the paper take-up mechanism 230. I will guide you. When the paper P is discharged from the paper outlet 217, the guide claw 272 rotates as described above to turn on the paper detection switch 276 (SW2). Based on this ON signal, the electric motor 256 (M2) Is driven to rotate forward, and the drive roller 243 mounted with the drive shaft 252 of the rotation drive mechanism 250 is driven to rotate in the direction indicated by the arrow in FIG. As a result, the disk-like members 233 and 233 that are frictionally engaged with the drive roller 243 are driven, and the paper take-up mechanism 230 is rotated in the forward rotation direction indicated by the arrow 232a. At this time, the pair of arms 241 and 241 of the locking means 240 are mounted on the rotary shaft 232 via the one-way clutch 243 and thus do not rotate and are held at the standby position shown in the figure. Accordingly, the paper P discharged from the paper outlet 217 is conveyed with its both ends nipped between the driving rollers 253 and 253 and the large-diameter disk-shaped members 233 and 233. At this time, the central portion of the front end of the paper P is guided by the guide claws 263 and guided between the small-diameter disk-shaped members 235 and 235 and the locking rollers 245 and 245 of the locking means 240, and is nipped between them. Be transported. The central portion of the front end of the paper P abuts on the paper abutting portions 242 and 242 of the pair of arms 241 and 241 held at the standby position as shown in FIG.
[0027]
When the disk-like members 233 and 235 are further rotated in the normal rotation direction indicated by the arrow 232a from the state shown in FIG. 5, the paper P is wound around the outer peripheral surfaces of the disk-like members 233 and 235 as shown in FIG. At this time, the pair of arms 241 and 241 are pushed by the front end of the paper P and rotate in the forward rotation direction indicated by the arrow 232a together with the disk-like members 233 and 235. Then, when the locking rollers 245 and 245 attached to the other ends of the pair of arms 241 and 241 rotate approximately once, the portion wound next to the paper P is outside the locking rollers 245 and 245. With the paper P, the guide claw 263 and the pair of holding members 265 and 265 are rotated clockwise in the figure against the spring force of the coil spring 264 around the drive shaft 252 as shown in FIG. When the paper P is further wound and the rear end of the paper P sent out from the paper carry-in path 216 passes through the paper outlet 217, the state shown in FIG. In this way, the paper P wound up by the paper winding mechanism 230 is wound around the large-diameter disk-shaped members 233 and 233 at its both ends, and the central portion is wound around the small-diameter disk-shaped members 235 and 235. Therefore, it is bent in a wave shape. Therefore, even if the paper P is curled, it is curled in a wave shape to remove this curl. In the illustrated embodiment, since friction members 234 such as urethane rubber are mounted on the outer peripheral surfaces of the two disk-like members 233 having a large diameter of the paper winding mechanism 230, the drive rollers 253, 253, and The paper P is surely driven.
[0028]
As shown in FIG. 6, when the rear end of the paper P passes through the paper outlet 217, the guide claw 272 is rotated counterclockwise in the drawing by the spring force of the coil spring 274 and the paper detection switch 276 (SW2) is turned OFF. . Based on this OFF, the electric motor 256 (M2) is driven in reverse, and the disk-like members 233 and 235 mounted on the rotary shaft 232 of the paper take-up mechanism 230 are rotated in the reverse direction indicated by the arrow 232b. As a result, the paper P taken up by the paper take-up mechanism 230 is rewound from the rear end, reversed front and back, guided by the guide claw 272 as shown in FIG. The paper is sent to the paper conveyance path 283 of the paper unit 280. Note that when the paper P taken up by the paper take-up mechanism 230 is rewound and the paper P taken up by the disk-like members 233 and 235 becomes one turn, the guide claw 263 and the pair of holding members 265, 265 is rotated counterclockwise about the drive shaft 252 by the spring force of the coil spring 264 from the state of FIG. 6 and is positioned in the state of FIG. Accordingly, in the pair of arms 241 and 241 that rotate together with the disk-shaped members 233 and 235, the support shaft 244 mounted on the other end is engaged with the engaging portions 266 and 266 provided on the pair of holding members 265 and 265. Then, it is stopped at the standby position shown in FIG.
[0029]
Even after the pair of arms 241 and 241 stop at the standby position shown in FIG. 7, the paper take-up mechanism 230 continues to rotate in the reverse direction, and the disk spring is retracted until the coil spring built in the one-way clutch 243 contracts. The members 233 and 235 are rotated, and the paper P is discharged from the nip portion between the driving rollers 233 and 253 and the large-diameter disk-shaped members 233 and 233. When the sheet detection switch 277 (SW3) detects the rear end of the sheet P that has been wound around the sheet winding mechanism 230 and sent out with the front and rear reversed, the driving of the electric motor 256 (M2) is stopped. This state is shown in FIG. The paper P sent out to the paper transport path 283 is turned upside down and transported by the transport roller pairs 284, 285 and 286, and is transported to the paper insertion path 141 and the paper cassette 134 provided in the device accommodating section 140. It is sent to the image forming machine main body 100 through the provided sheet insertion path 135, and an image is formed on the other side. In the illustrated embodiment, the paper P taken up by the paper take-up mechanism 230 has the rear ends whose front and back are reversed when being rewound, and the paper abutting portions 242 and 242 of the pair of arms 241 and 241. Therefore, even when it is inclined when being conveyed from the image forming machine main body 100, it can be corrected.
[0030]
Next, the control means 400 will be described with reference to FIG. The control means 400 is constituted by a microcomputer, and a central processing unit (CPU) 401 that performs arithmetic processing according to a control program, a read-only memory (ROM) 402 that stores a control program, and a read / write that stores arithmetic results and the like. A random access memory (RAM) 403, a timer (T) 404, an input interface 405, and an output interface 406. In addition to the paper detection switches 275 (SW1), 276 (SW2), and 277 (SW3), the input interface 405 includes detection signals from various detection means disposed in the image forming machine main body 100 and the image forming machine main body 100. A control signal or the like from the connected computer is input. In addition to the electric motor 225 (M1), the electric motor 256 (M2), and the electromagnetic solenoid 228 (SOL1), the output interface 406 is used to rotate and drive the conveyance roller pairs 284, 285, and 286 of the duplex feeding unit 280. A control signal is output to each operating device of the motor and the image forming machine main body 100.
[0031]
The operation procedure of the inversion control of the control means 400 described above will be described with reference to the flowchart shown in FIG.
The control unit 400 first checks whether or not the sheet detection switch 275 (SW1) is turned on, that is, whether or not the sheet P is sent from the image forming machine main body 100 to the sheet inlet 214 of the sheet carry-in path 216 (step S1). ). If the paper detection switch 275 (SW1) is turned on, the paper P has been transported to the paper carry-in path 216, so the control means 400 proceeds to step S2 and drives the electric motor 225 (M1). By driving the electric motor 225 (M1), the conveyance roller pairs 222 and 224 are rotationally driven. Then, the control means 400 proceeds to step S3 and checks whether or not an inversion flag is set. This is to determine whether or not the paper P conveyed to the paper carry-in path 216 is the first time, that is, whether an image is formed on only one side of the paper P or an image is formed on both sides. Since the reverse flag is not initially set (“0”), the control unit 400 proceeds to step S4 and energizes the electromagnetic solenoid 228 (SOL1). When the electromagnetic solenoid 228 (SOL1) is energized, the branching claw 227 is positioned at the second position shown in FIG. As a result, the paper P sent to the paper inlet 214 of the paper carry-in path 216 is transported by the transport roller pairs 222 and 224 and discharged from the paper outlet 217 toward the paper take-up mechanism 230.
[0032]
Next, the control means 400 proceeds to step S5 and checks whether or not the paper detection switch 276 (SW2) is turned on, that is, whether or not the front end of the paper P has passed the paper outlet 217, and must be turned on. For example, the front end of the paper P does not reach the paper outlet 217 and waits. If it is turned on, it is determined that the front end of the paper P has passed the paper outlet 217, and the process proceeds to step S6 to rotate the electric motor 256 (M2) forward. To drive. When the electric motor 256 (M2) is driven to rotate in the forward direction, the driving roller 253 rotates in the direction indicated by the arrow 253a in FIG. 5, and the large-diameter disk of the paper winding mechanism 230 that is in frictional contact with the driving roller 253. The member 233 is driven and the sheet winding mechanism 230 is driven to rotate in the direction indicated by the arrow 232a. On the other hand, the paper P guided by the branching claw 227 and discharged toward the paper take-up mechanism 230 is nipped between the drive rollers 233 and 253 and the large-diameter disk-shaped members 233 and 233 and conveyed. Then, the central portion of the front end of the paper P is guided by the guide claw 263 and passes between the small-diameter disk-shaped members 235 and 235 and the locking rollers 245 and 245 of the locking means 240 as shown in FIG. The pair of arms 241 and 241 held at the positions are in contact with the sheet contact portions 242 and 242 of the arms. Then, the paper take-up mechanism 230 further rotates in the normal rotation direction indicated by the arrow 232a, whereby the paper P is taken up by the paper take-up mechanism 230.
[0033]
As described above, if the electric motor 256 (M2) of the paper take-up mechanism 230 is driven forward to start the take-up of the paper P, the control unit 400 proceeds to step S7 and advances to the paper detection switch 276 (SW2). ) Is turned off, that is, whether the trailing edge of the paper P has passed through the paper outlet 217 is checked. If the paper detection switch 276 (SW2) is not turned OFF, the rear end of the paper P does not pass through the paper outlet 217, and waits. If the paper detection switch 276 (SW2) is turned OFF, the control means 400 will It is determined that the end has passed the paper exit 217, and the process proceeds to step S8, where the electric motor 225 (M1) is stopped and the electromagnetic solenoid 228 (SOL1) is energized. The state at this time is shown in FIG.
[0034]
Then, the control means 400 proceeds to step S9 and reversely drives the electric motor 256 (M2) that is normally driven as described above. When the electric motor 256 (M2) is driven in reverse, as described above, the paper take-up mechanism 230 is rotated in the reverse direction indicated by the arrow 232b, and the paper P is rewound from the rear end and guided by the guide claw 272 to discharge the paper. Through the path 270, the paper is sent to the paper transport path 283 of the duplex paper feeding unit 280. Then, when the paper P wound up by the paper take-up mechanism 230 becomes one roll, the guide claws 263 and the pair of holding members 265 and 265 are positioned in the state of FIG. 7 as described above. Therefore, in the pair of arms 241 and 241 that rotate together with the paper take-up mechanism 230, the support shaft 244 attached to the other end engages with the engaging portions 266 and 266 provided on the pair of holding members 265 and 265. Thus, the vehicle is stopped at the standby position shown in FIG. Thereafter, the disk-shaped members 233 and 235 are rotated until the coil spring built in the one-way clutch 243 contracts, and the paper P is a nip portion between the driving rollers 233 and 253 and the large-diameter disk-shaped members 233 and 233. Discharged from.
[0035]
If the electric motor 256 (M2) is reversely driven as described above, the control means 400 proceeds to step S10 and checks whether or not the paper detection switch 277 (SW3) is turned off. The sheet detection switch 277 (SW3) is turned on when the sheet P is conveyed to the nip portion between the driving rollers 233 and 253 of the sheet winding mechanism 230 and the large-diameter disk-shaped members 233 and 233, and then turned on. When the state is maintained and the sheet take-up mechanism 230 is reversely driven as described above and the rear end of the sheet P reversed in the front-rear direction is discharged from the nip portion, it is turned OFF. Instead of the paper detection switch 277 (SW3) that detects the discharge of the paper P from the paper take-up mechanism 230, it can be processed in software. That is, the size of the paper P used is stored, and the number of rotations of the electric motor 256 (M2) after the paper winding mechanism 230 starts rewinding is counted to correspond to the size of the paper P. The electric motor 256 (M2) may be turned off when the number of rotations to be reached is reached. In step S10, if the paper detection switch 277 (SW3), which has been turned on, is turned off, the control unit 400 proceeds to step S11 and stops driving the electric motor 256 (M2). This state is shown in FIG. Then, the control unit 400 proceeds to step S12 and sets an inversion flag (“1”).
[0036]
If the reversal control of the paper P with the image formed on one side is executed as described above, the control unit 400 returns to step S1. In step S1, the control unit 400 checks whether or not the paper detection switch 275 (SW1) is turned on. If the paper detection switch 275 (SW1) is turned on, the paper P has been transported to the paper carry-in path 216. In step S2, the electric motor 225 (M1) is driven, and in step S3, it is checked whether or not the reverse flag is set. Since the reversal flag is set (“1”) in step S12 this time, the control means 400 proceeds to step S13 and deenergizes the electromagnetic solenoid 228 (SOL1) (note that in step S8, the electromagnetic solenoid 228 ( Since SOL1) is de-energized, the de-energized state is maintained in step S13). When the electromagnetic solenoid 228 (SOL1) is de-energized, the branching claw 227 is positioned at the first position indicated by a solid line in FIG. Therefore, the paper P on which images are formed on both sides conveyed by the conveyance roller pair 222 is guided on the branch claw 227 and disposed on the unit housing 212 through the discharge port 213 provided on the upper wall of the unit housing 212. To the stacking tray 290. Then, the control unit 400 proceeds to step S14, clears the reverse flag ("0"), returns to step S1, and repeatedly executes steps S1 to S14 until the number corresponds to the number of prints.
[0037]
Next, another embodiment of the sheet reversing unit 210 will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the substantially same member as embodiment shown in the said FIG. 2 thru | or FIG. 8, and detailed description is abbreviate | omitted.
The sheet reversing unit 210 in the embodiment shown in FIG. 11 has a rotation direction of a sheet take-up mechanism 230 having a rotating shaft 232 and two types of disk-shaped members 233 and 235 arranged on the rotating shaft 232 and having different diameters. These are configured in the opposite direction to the embodiment shown in FIGS. That is, when winding a sheet, the sheet winding mechanism 230 is rotated clockwise in FIG. 11 (arrow 232c), and when the sheet is rewound, the sheet winding mechanism 230 is rotated counterclockwise (arrow 232d in FIG. 11). ) To be rotationally driven. In this way, the paper take-up mechanism 230 is configured in the direction opposite to the embodiment shown in FIGS. 2 to 8, so that the paper carry-in path 216 is formed on the right side of the paper take-up mechanism 230 in FIG. At the same time, a branching claw 227 is disposed at the paper inlet 214 from the conveying roller pair 222. The bending direction of the paper contact portion 242 formed at the intermediate portion of the arm 241 constituting the locking means 240 and the mounting direction of the guide means 260, the holding member 265, and the guide claw 272 are shown in FIGS. It is configured in the opposite direction to the embodiment shown. Accordingly, the paper take-up mechanism 230, the guide unit 260, and the holding member 265 guide claw 272 constituting the paper reversing unit 210 operate in the reverse direction to the embodiment shown in FIGS.
[0038]
As described above, the sheet reversing device of the image forming machine configured according to the present invention has been described based on the embodiment applied to the laser beam printer. However, the present invention is not limited to the embodiment, and various types such as an electrostatic copying machine. It can be applied to other image forming machines.
[0039]
【The invention's effect】
Since the paper reversing device of the image forming machine according to the present invention includes the paper winding mechanism and is configured to wind the paper that is reversed by the paper winding mechanism, the paper can be reversed in a small space. In addition, since the paper take-up mechanism includes at least two types of disk-like members with different diameters arranged at intervals in the axial direction, the paper taken up by the paper take-up mechanism is curved in a wave shape. It is done. Therefore, even if the paper is curled, it is curled in a wave shape to remove this curl.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a laser beam printer as an image forming machine equipped with a sheet reversing device configured according to the present invention.
FIG. 2 is a cross-sectional view showing a position embodiment of a sheet reversing device configured according to the present invention.
3 is a perspective view showing a paper take-up mechanism and a rotation drive mechanism that constitute the paper reversing device shown in FIG. 2;
4 is a perspective view showing a guide means constituting the paper reversing device shown in FIG. 2. FIG.
FIG. 5 is a cross-sectional view showing an operating state of the sheet reversing device shown in FIG. 2;
6 is a cross-sectional view showing an operating state of the sheet reversing device shown in FIG. 2;
7 is a cross-sectional view showing an operating state of the sheet reversing device shown in FIG. 2;
8 is a cross-sectional view showing an operating state of the paper reversing device shown in FIG.
9 is a block diagram of control means for controlling the operation of the sheet reversing device shown in FIG.
FIG. 10 is a flowchart showing an operation procedure of the control means shown in FIG. 9;
FIG. 11 is a cross-sectional view showing another embodiment of a sheet reversing device configured according to the present invention.
[Explanation of symbols]
100: Image forming machine body
101: Housing
104: Photoconductor drum
106: Corona discharger for charging
108: Developing device
110: Transfer roller
112: Cleaning device
116: Laser unit
120: Paper transport path
122: Paper feed roller pair
124: Registration roller pair
126: Fixing roller pair
128: Transport roller pair
130: Branch claw
132: discharge roller pair
134: Paper cassette
136: Feeding roller
138: Rolling roller pair
200: Reverse paper feeding unit
210: Paper reversing unit
212: Unit housing
216: Paper carry-in route
222, 224: Conveying roller pair
225: Electric motor (M1)
227: Branch nail
228: Electromagnetic solenoid (SOL1)
230: Paper winding mechanism
232: Rotating shaft
223: disk-shaped member having a large diameter
234: Friction member
235: disk-shaped member having a small diameter
240: Locking means
241: Arm
242: Paper contact portion
243: One-way clutch
245: Locking roller
250: Rotation drive mechanism
252: Drive shaft
253: Driving roller
254: Gear
256: Electric motor (M2)
257: Drive gear
260: Guide means
262: Support member
264: Coil spring
265: Holding member
270: Paper discharge path
272: Guide nails
274: Coil spring
275: Paper detection switch (SW1)
276: Paper detection switch (SW2)
277: Paper detection switch (SW3)
280: Duplex paper feeding unit
282: Unit housing
283: Paper transport path
284, 285, 286: pair of transport rollers
290: Loading tray
400: Control means

Claims (8)

In a paper reversing device of an image forming machine that reverses and conveys a paper having an image formed on one side,
A paper carry-in path for carrying paper with an image formed on one side;
The rotary shaft, at least two types of disc-shaped members having different diameters arranged at intervals in the axial direction on the rotary shaft, and the outer peripheral surface of one of the two types of disc-shaped members are conveyed. A paper take-up mechanism for taking up the paper carried into the paper carry-in path,
A rotational drive mechanism having a drive roller disposed in contact with the outer peripheral surface of the other disk-shaped member of the two types of disk-shaped members, and a drive source for driving the drive roller to rotate forward and reversely;
A paper discharge path for discharging the paper that has been rewound after being taken up by the paper take-up mechanism,
A sheet reversing device for an image forming machine. The locking means is disposed to face one disk-shaped member having a small diameter of the two types of disk-shaped members, and the drive roller is disposed to face the other disk-shaped member having a large diameter. The image forming machine according to claim 1. The image forming machine according to claim 1, wherein a friction member having a large friction coefficient is mounted on an outer peripheral surface of the other disk-shaped member of the two types of disk-shaped members. The image forming machine according to claim 1, wherein the locking unit includes a locking roller that clamps a leading end of the sheet between the outer peripheral surface of the other disk-shaped member. The image forming machine according to claim 4, wherein the locking roller is formed of an elastic member. The image forming machine according to claim 1, wherein the locking unit includes a contact unit configured to contact a front end of the sheet. The image forming machine according to claim 6, wherein the locking means includes an arm having one end attached to the rotating shaft via a one-way clutch, and the arm is provided with a corresponding contact means. 5. The image forming machine according to claim 4, wherein the locking means includes an arm having one end mounted on the rotating shaft via a one-way clutch, and the locking roller is mounted on the other end of the arm. .

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