Patent Application
20060181015
1. Field of the Invention
The present invention relates to a releasing device for releasing a pair of conveying members configured to convey a sheet while nipping it therebetween and an image forming apparatus including the same.
2. Description of the Background Art
It is a common practice with a printer, copier or similar image forming apparatus to convey a sheet with a pair of conveying members. When a sheet jam or similar conveyance error occurs on a sheet path arranged in such an image forming apparatus, the operator of the apparatus usually stops the operation of the apparatus, locates the sheet jam and then removes a jamming sheet by hand. However, if the apparatus stops operating with the conveying members held in contact with each other, then a sheet nipped between the conveying members cannot be easily removed and, moreover, it is apt to be conveyed deeper into the apparatus by the conveying members after the sheet jam. This makes jam processing extremely troublesome.
In light of the above, Japanese Patent Laid-Open Publication No. 7-237782(=U.S. Pat. No. 5,544,580) proposes a system applied to a pair of feed rollers one of which is selectively movable toward or away from the other and conveying, when moved toward the other feed roller, a sheet by nipping it and including preventing means for preventing, when a conveyance error is sensed on a sheet path, the one feed roller from being moved toward the other feed roller. The preventing means includes a cam for causing an arm to move in a contacting/releasing direction, a stop protruding into the locus of angular movement of the arm member for stopping the arm member, and drive means for moving the stop. When a conveyance error occurs, the drive means is energized to prevent the arm member from moving in the contacting direction. The cam is rotated to cause the arm member to angularly move for thereby moving one of the two feed rollers into or out of contact with the other feed roller.
The conventional system described above has the following problem left unsolved. Assume that the drive means assigned to the arm member is energized due to a sheet jam or similar conveyance error occurred when the two feed rollers are held in contact with each other. Then, the arm member prevents the stop from smoothly protruding into the locus of angular movement of the arm member. Stated another way, the stop cannot function at all unless the cam holds the arm member in the releasing position. Therefore, even if the drive means assigned to the stop is energized as soon as, e.g., a sheet jam is sensed, the feed rollers, contacting each other, cannot be released immediately in dependence on the position of the arm member. As a result, the feed rollers convey a sheet and aggravate the sheet jam condition, rendering recovery work extremely troublesome.
Technologies relating to the present invention are also disclosed in Japanese Patent Laid-Open Publication No. 6-1492.
It is an object of the present invention to provide a releasing device promoting easy removal of a jamming sheet and an image forming apparatus including the same.
A releasing device of the present invention selectively moves one of a pair of conveying members for conveying a sheet into or out of contact with the other conveying member. A first moving device moves the one conveying member into or out of contact with the other conveying member. A second moving device 72 is connected to the first moving device for moving the one conveying member in a releasing direction independently of the operation of the first moving means.
An image forming apparatus including the above releasing means is also disclosed.
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken with the accompanying drawings in which:
Referring to
An image scanner or image reading section 40 is mounted on the top of the printer body 1 and has a conventional construction including a scanning unit 41A and a CCD (Charge Coupled device) image sensor or similar image sensor 41B. While the scanning unit 41A reads a document image, image data scanned by the scanning unit 31A are input to the image sensor 41B.
Mores specifically, the sheet feeding section 3 includes a sheet tray 10 loaded with a stack of sheets 2. Feed rollers 11 cooperated to pay out the top sheet 2 from the sheet tray 10 toward a registration roller pair or conveying member pair 12 while separating the underlying sheets from the top sheet. The registration roller pair 12 once stops the sheet to correct skew thereof and then conveys it toward the printing section 4 at preselected timing.
A sheet path 26 extends from the feed rollers 11 to the printing section 4. The registration roller pair 12 is made up of a drive roller or elastic member 12A formed of rubber and facing the sheet path 26 from below the same and a driven roller 12B formed of resin and facing the sheet path 26 from above the same. The driven roller 12B is held in contact with the drive roller 12A in such a manner as to be releasable from the latter, as will be described specifically later. The driven roller 12B may be formed of metal, if desired.
A stepping motor or drive motor 28 causes the drive roller 12A to rotate. The driven roller 12B, contacting the circumference of the drive roller 12A, is caused to rotate by the drive roller 12A. A jam sensor or conveyance error sensing means 27 is positioned on part of the sheet path extending between the registration roller pair 12 and the printing section 4. The jam sensor 27 is configured to output a jam signal on sensing a sheet jam, which is a specific conveyance error.
A master making section 7 is located at the upper right of the printing section 4 and includes a stencil storing section 14 in which a stencil 13 is stored in the form of a roll. A thermal head 15 and a platen roller or platen conveying member 16 are held in contact with each other at a positioned downstream of the master storing section 14 in a direction in which the stencil 13, paid out from the roll, is conveyed. Let this direction be referred to as a direction of stencil conveyance hereinafter. A cutter or cutting means 17 and a roller pair or stencil conveying member pair 18 are arranged downstream of the thermal head 15 and platen roller 16 in the direction of stencil conveyance. With this configuration, the master making section 7 perforates, or cuts, the stencil 13 in accordance with image data to thereby produce a master 19 and conveys the master 19 toward the printing section 4.
The printing section 4 is formed between a print drum 20 and a press roller or pressing member 22. The print drum 20 is a porous, hollow cylindrical body configured such that the master 19 produced by the master making section 7 is to be wrapped around its outer periphery 20a. The press roller 22 is selectively moved into or out of contact with the outer periphery 20aof the drum 20 by a mechanism, not shown, and presses, when moved into contact with the periphery 20a, the sheet 2 against the periphery 20a. The press roller 22, serving as a pressing member, may be replaced with a conventional print drum, if desired.
Ink feeding means 9 is arranged within the print drum 20 and made up of an ink conveying member 21 and a doctor conveying member 8. When the press roller 22 presses the sheet 2 fed from the sheet feeding section 3 against the master 19 wrapped around the drum 20, ink fed from the ink feeding means 9 is transferred to the sheet 2 via the print drum 20, forming an image on the sheet 2. A sheet discharging device is arranged at the upper left of the print drum 20 in order to peel off the used master 19 from the drum 20 and discard it, although not shown specifically. The print drum 20 is caused to rotate clockwise, as viewed in
In the illustrative embodiment, the print drum 20 and registration roller pair 12 each are driven by a respective motor. Alternatively, the main motor 29 and drive roller 12A may be operatively connected to each other by any conventional drive transmission mechanism including, e.g., gears or pulleys so as to interlock the print drum 20 and registration roller pair 12.
The sheet discharging section 6 includes a peeler 23 for peeling off the sheet 2 adhering to the master 19 on the print drum 20 due to the viscosity of ink. A belt conveyor 25 conveys the sheet 2 coming out of the printing section 4 while sucking it with a suction fan 24. Such sheets or prints, sequentially driven out of the printer body 1, are sequentially stacked on a print tray 35.
As shown in
More specifically, the first moving means 72 includes a pair of arms or angularly movable members 73A and 73B supporting the driven roller 12B and moving it into or out of contact with the drive roller 12A. A pair of coiled tension springs or biasing members 74A and 74B cooperate to constantly bias the arms 73A and 73B toward the drive roller 12A. A cam member 75 is rotatably connected to the arm 73A and rotatable to move the arms 73A and 73B in a contacting/spacing direction.
As shown in
Opposite ends of the shaft 76 are affixed to one end 73aof the arms 73A and 73B. The other ends 73bof the arms 73A 25 and 73B are affixed to a rotatable shaft 78 journalled to the printer body 1,
A cam follower arm 81 is affixed to the end 78aof the rotatable shaft 78 at one end 81band therefore angularly movable in interlocked relation to the arm members 73A and 73B. A roller 80 is rotatably mounted on the other or free end 81aof the cam follower arm 81. The cam member 75 is operatively connected to a drive transmission mechanism, not shown, in such a manner as to rotate about a shaft 82 in synchronism with the rotation of the print drum 20 when the main motor 29 is energized. In the illustrative embodiment, the can member 78 is configured to make a single rotation in synchronism with a single rotation of the print drum 20.
The cam member 75 has a circumferential cam surface 75afacing the roller 80 of the cam follower arm 81. The roller 80 is constantly pressed against the cam surface 75aby the force of the tension springs 74A and 74B. The cam surface 75aof the cam member 75 has a profile configured to maintain the driven roller 12B in contact with the drive roller 12A, as shown in
The second moving means 72 includes a pin 85 studded on the rotatable shaft 78. A link member 86 is connected to the arm members 73A and 73B at one end 86athereof via the pin 85 and shaft 78. A release motor 87 is drivably connected to the other end 86bof the link member 86 in order to move the link member 86 in a direction in which the arm members 73A and 73B move the driven roller 12B away from the drive roller 12A. This direction will be referred to as a releasing direction hereinafter.
A slot 89 is formed in one end portion 86aof the link member 86 and extends in the releasing direction mentioned above. The pin 85, studded on the shaft 78, is loosely fitted in the slot 89. This configuration prevents the link member 86 from being displaced when the arm members 73A and 73B are angularly moved by the cam member 75.
A worm gear 88 is mounted on the output shaft of the release motor 87, which is implemented as a stepping motor or a DC motor, and held in mesh with a gear portion 90 formed at the other end 86bof the link member 86. In this condition, when the release motor 87 is driven to rotate the worm gear 88 clockwise, as viewed in
The jam sensor 27 and image scanner 40 and a control panel 60 are connected to the input side of the control unit 50. The control panel 50 includes a release key switch or release commanding means 61 for outputting a release command signal and a return key switch or return commanding means 62 for outputting a return command signal. The operator of the printer may operate the release key switch 61 when desiring to release the driven roller 12B from the drive roller 12A or operate the return key switch 62 after the removal of a jamming sheet or when desiring to return the driven roller 12B to the contact position.
Controlling the various drive sections of the printer, as needed, the control unit 50 controls the entire printing operation of the printer body 1. Further, when a jam signal is input to the control unit 50 from the jam sensor 27, the control unit 50 drives the release motor 87 in a direction that causes the link member 86 to move in the releasing direction, while interrupting the operation of the other devices. Also, when a release command signal is input to the control unit 50 from the release key switch 61, the control unit 50 drives the release motor 87 in the above direction. When the operator operates the return key switch 61, the control unit 50 drives, in response to the resulting return command signal, the release motor 87 in the opposite direction that causes the link member 86 to return to its initial position.
The operation of the illustrative embodiment will be described hereinafter. Assume that the master 19 is wrapped around the circumferential surface 20aof the print drum 20 beforehand.
When the operator of the printer inputs a desired number of prints on ten keys, not shown, arranged on the control panel 60 and then operates a conventional print start key, the control unit 50 causes the sheet-feed drive section 42 to rotate the feed rollers 11 for thereby feeding the top sheet 2 from the sheet tray 10. Further, the control unit 50 causes the print drive section 45 to rotate the print drum 20 at a peripheral speed matching a preselected print speed. At this instant, although the driven roller 12B is held in contact with the drive roller 12A, as shown in
At preselected registration timing, the control unit 50 starts driving the stepping motor 28. Consequently, the registration roller pair 12 starts conveying the sheet 2 toward the printing section 4 between the print drum 20 and the press roller 22. Then, the press roller 22 is brought into contact with the print drum 20 for forming an image on the sheet 2.
More specifically, when the leading edge of the sheet 2 is nipped between the print drum 20 and the press roller 22 at the printing section 4, the cam 75 with the profile stated previously pushes the cam follower arm 81 upward little by little with the result that the shaft 78 rotates clockwise, as viewed in
When the driven roller 12B is released from the drive roller 12A, the sheet 2, now free from the resistance of the registration roller pair 12, is conveyed in accordance with the peripheral speed of the print drum 20. Although the pin 85 moves in interlocked relation to the arm members 73A and 73B, the slot 89 absorbs the movement of the pin 85 to thereby prevent the link member 86 from moving in the releasing direction and exerting a load on the release motor 87. The sheet 2, carrying an image transferred thereto from the master 19 at the printing section 4, is driven out to the print tray 25 by the belt conveyor 25, which includes the suction fan 24,
When the operation stated above is repeated a number of times corresponding to the desired number of prints input by the operator, the control unit 5O causes the printer to stop operating.
Assume that the jam sensor 27 outputs a jam signal when the printer is in operation. Then, the control unit 50 drives the release motor 87 while interrupting the operation of the other sections of the printer. As shown in
As stated above, in the illustrative embodiment, as soon as the jam sensor 27 senses a jam, the printer immediately stops operating and causes the release motor 87 to move the arm members 73A and 73B and cam follower arm 81 in the spacing direction. As a result, the driven roller 12 and drive roller 12A are immediately released from each other without regard to the position of the cam member 75. This prevents the sheet 2 from being conveyed by the drive roller 12A and driven roller 12B pressed against each other in the direction X and therefore prevents the sheet jam from being aggravated, allowing the operator to easily remove a jamming sheet 2.
Moreover, the link member 86 and release motor 87 are interconnected by the gear portion 90 and worm gear 88 held in mesh with each other. It follows that even if the power supply to the release motor 87 is shut off while the operator is dealing with a sheet jam, the arm members 73A and 73B and cam follower arm, 81 are prevented from being returned toward the contact position under the action of the tension springs 74A and 74B. This further promotes easy removal of a jamming sheet 2.
On the other hand, to return the driven roller 12B to the position where it contacts the drive roller 12A, the operator operates the return key switch 62. In response, the control unit 50 causes the release motor 87 to rotate in the direction opposite to the direction in which it rotated in the event of release, so that the link member 86 moves leftward, as viewed in
Now, it may occur that the stencil printer is left unused over a long time, depending on the user's circumstances. This brings about a problem that if the driven roller 12B is pressed against the drive roller 12A throughout the unused period, then the rollers 12A and 12B are apt to deform due to the force of the tension springs 74A and 74B constantly acting thereon. The illustrative embodiment solves this problem with the following configuration.
The operator of the printer operates the release key switch 61. In response to the resulting release command signal output from the release key switch 61, the control unit 50 drives the release motor 87 to cause the link member 86 to move in the releasing direction, i.e., rightward in
As stated above, in the illustrative embodiment, the operator may operate the release key switch 61 any time in order to release the driven roller 12B from the drive roller 12A without regard to the position of the cam member 75. This successfully protects the drive roller 12A and driven roller 12B from deformation ascribable to the force of the tension springs 74A and 74B even when the printer is left unused over a long time.
Reference will be made to
When the jam sensor 27 outputs a jam signal during the operation of the printer, the control unit 50A energizes the solenoid 97 while interrupting the operation of the other sections of the printer. As shown in
As stated above, in the modification, as soon as the jam sensor 27 senses a jam, the printer immediately stops operating and causes the solenoid 97 to move the arm members 73A and 73B and cam follower arm 81 in the spacing direction. As a result, the driven roller 12 and drive roller 12A are immediately released from each other without regard to the position of the cam member 75. This prevents the sheet 2 from being conveyed by the drive roller 12A and driven roller 12B pressed against each other in the direction X and therefore prevents the sheet jam from being aggravated, allowing the operator to easily remove a jamming sheet 2.
Again, to return the driven roller 12B to the position where it contacts the drive roller 12A, the operator operates the return key switch 62. In response, the control unit 50 deenergizes the solenoid 97. As a result, the force of the tension springs 74A and 74B and the total weight of the arms and rollers act on the link member 86 and cause it to move leftward, as viewed in
In the illustrative embodiment and modification thereof described above, the releasing device 70 is applied to the registration roller pair 12 by way of example. However, the releasing device 70 is similarly applicable to any other conveying members that cooperate to convey the sheet 2 while nipping it therebetween. Also, conveying members to which the releasing device 70 is applicable are not limited to a pair of rollers. For example, a pair of rollers may be replaced with the combination of a drive belt member and a driven roller member contacting or preferably pressed against the belt member or the combination of a drive belt member and a driven belt member contacting or pressed against each other. If desired, the cooperative conveying members may even be replaced with members neither one of which is driven or both of which are driven.
It should be noted that the stencil printer including the releasing means 70 shown and described is merely an example of a printer. Further, the printer may be replaced with any other image forming apparatus, e.g., a conventional electrophotographic image forming apparatus in which an image transfer station is formed between a photoconductive element or image carrier, which is implemented as a drum or a belt on which a toner image is to be formed, and an image transfer member implemented as a roller or a belt and configured to transfer the toner image to a sheet.
In summary, it will be seen that the present invention provides a releasing device capable of allowing a jamming sheet to be easily removed with first moving means for moving one of two conveying members into or out of contact with the other conveying member and second moving means connected to the first moving means for moving the one conveying member away from the other conveying member independently of the first moving means.
Various modifications will become possible for those skilled in the art after receiving the teachings of the present disclosure without departing from the scope thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-314585 (JP) | Oct 2004 | JP | national |
