JP3548316B2 - Paper supply device and image forming device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sheet supply device provided in an image forming apparatus such as a printer and a copying machine, and an image forming apparatus including such a sheet supply device.
[0002]
[Prior art]
Conventionally, a paper feeding device such as a printer or a copier is provided with a separation feeding device including a pair of rollers and a paper feeding device for feeding a sheet to the separation feeding device, and a plurality of rollers from the separation feeding device. There has been proposed a configuration in which paper is conveyed to a printer, a copier, or the like via a printer.
[0003]
[Problems to be solved by the invention]
However, the sheet feeding means and the sheet separating / feeding means may skew the sheet due to the way of setting the sheet and the uneven friction force between the roller and the sheet and the friction force between the sheets. If the transport distance from the paper position to the image forming apparatus is long, the paper may be wrinkled or an image may not be obtained at an appropriate position.
[0004]
[Means for Solving the Problems]
According to the present invention, a skew removing roller (13) is provided, and as a means for increasing the sheet conveying force, the sheet separating / feeding means (11, 12) is controlled by using the sheet feeding means (10) or the sheet position. The present invention relates to a paper feeding apparatus having a mechanism for stabilizing a skew feeding effect.
[0005]
[Action]
According to the above configuration, the sheet (S) reaches the skew feeding roller even if the conveying force of the sheet separating / feeding means (11, 12) of the normal setting decreases and the conveying speed of the sheet (S) decreases. Before the transfer, the transport force of the sheet (S) increases, and the sheet (S) abuts against the stopped skew removing roller (13), so that the skew can be suppressed stably.
[0006]
The reference numerals in the parentheses are for referring to the drawings, and do not limit the configuration.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0008]
<First embodiment>
FIG. 5 shows an outline of the sheet supply apparatus and the image forming apparatus. Reference numeral 1 denotes an image forming apparatus, which is connected to a sheet supply device 2. Reference numeral 3 denotes a paper storage, and 4 denotes a paper loading plate on which paper S is loaded. Reference numeral 10 denotes a pickup roller that is a sheet supply unit. Reference numeral 11 denotes a feed roller, and reference numeral 12 denotes a retard roller. The pair of rollers constitutes a separating / feeding unit. Reference numeral 13 denotes a pair of skew feeding rollers, reference numeral 14 denotes a paper detection sensor, and reference numeral 15 denotes a paper guide.
[0009]
FIG. 6 shows a paper feeding mechanism. Reference numeral 20 denotes a pickup shaft, which moves up and down by the movement of the pickup swing arm 17. The pickup swing arm 17 is in contact with the pickup cam 18. The feed roller 11 is driven to rotate by a feed roller drive shaft 21 and a feed gear 31. Reference numeral 16 denotes a torque limiter which transmits the rotation of the retard drive shaft 22 and the retard gear 32 in the direction opposite to the sheet conveyance direction to the retard roller 12 up to a set torque value.
[0010]
When the sheet is not between the feed roller 11 and the retard roller 12, the separation feed unit rotates the retard roller 12 in the sheet conveying direction by the operation of the torque limiter 16, and feeds the sheet in the forward direction when the sheet S is supplied. One or more sheets S are supplied from the pickup roller 10 to the separation feeding section from the uppermost portion placed on the sheet stacking plate 4, and two or more sheets S are supplied to the nip portion of the roller pair. When the sheet enters, the retard roller 12 rotates in the direction opposite to the sheet supply direction, and returns the sheets other than the topmost sheet to the upstream to sequentially feed the topmost sheet one by one. After a predetermined time T elapses after the leading edge of the sheet S conveyed from the separation feeding unit passes through the sheet detection sensor 14, the skew removing roller 13 is driven.
[0011]
The image forming apparatus 1 is provided with a front loading type sheet cassette mounted from the front. The sheets S2 stored in the sheet cassette are separated and sent out one by one by sheet separation and feeding means similar to the pickup roller 10, the feed roller 11, and the retard roller 12. An image is formed by the image forming unit 101 on the sheet fed from the sheet cassette and the deck 2.
[0012]
The image forming unit 101 has a process cartridge 102 detachable from the image forming apparatus main body. The process cartridge 102 includes an electrophotographic photosensitive drum 103 serving as an image carrier, and a charging unit 104 for charging the surface of the photosensitive drum 103. And a developing unit for forming a toner image on the photosensitive drum 103, a cleaning unit 106 for removing the toner image remaining on the surface of the photosensitive drum 103, and the like. The photosensitive drum 103 is exposed by image light emitted from the scanner unit 107 according to an image signal.
[0013]
The image forming unit 101 is further provided with a transfer roller 108 for transferring the toner image formed on the surface of the photosensitive drum 103 to a sheet. The transfer roller 108 presses the sheet fed from the sheet cassette or the deck 2 onto the photosensitive drum 103. The transfer roller 108 applies a voltage having a polarity opposite to that of the toner image to the transfer roller 108 so that the toner image on the surface of the photosensitive drum 103 is removed. The toner image on the surface of the photosensitive drum 103 is transferred to a sheet by applying a voltage of the opposite polarity.
[0014]
A fixing unit 109 is provided downstream of the image forming unit 101 in the sheet flow direction. A fixing roller 110 is provided in the fixing unit 109, and the toner image transferred to the sheet in the image forming unit 101 is fixed by applying heat and pressure by the fixing roller 110. Then, the sheet on which the toner image is fixed is discharged onto the discharge tray 111.
[0015]
1 to 4 show a sheet feeding operation of the sheet feeding device according to the first embodiment of the present invention. FIG. 1 shows a paper supply standby state, and FIG. 2 shows a paper supply state. When the pickup cam 18 rotates based on a paper supply instruction, the pickup roller 10 comes into contact with the paper S and supplies the paper S. . FIG. 3 shows a sheet separation state, in which the pickup roller 10 returns to the standby position, and the sheet S is separated and conveyed by the roller pair of the feed roller 11 and the retard roller 12, which are sheet separation and feeding means, as described above. FIG. 4 illustrates a skew feeding state, in which the leading end of the sheet S reaches the sheet detection sensor 14, and the pickup roller 10 abuts on the sheet S being conveyed again to hit the sheet S against the skew feeding roller.
[0016]
According to the above embodiment, the skew feeding roller is provided, and the sheet is fed by the pickup roller toward the roller. Stable skew removal can be performed.
[0017]
<Embodiment 2>
FIG. 7 shows a second embodiment according to the present invention. Reference numeral 41 denotes a retard spring, one of which is attached to a retard arm 40 which holds the retard roller shaft 22, and the other of which is attached to a retard spring attaching member 42 which is rotatable around a support portion 45. The retard spring mounting member 42 abuts against a stopper 43. A solenoid 44 is connected to the retard spring mounting member.
[0018]
The process from the sheet feed command to before the skew feeding is the same as in the first embodiment, and a description thereof will be omitted. FIG. 8 shows a skew feeding state. When the leading end of the sheet S reaches the sheet detection sensor 14, the solenoid 44 is operated, and the retard spring mounting member 42 connected to the solenoid 44 is moved in the direction in which the retard spring 41 extends. , The tension generating force of the retard spring increases, and the nip pressure between the feed roller 11 and the retard roller 12 increases. The sheet S is abutted against the skew feeding roller 13 by the increased conveying force. When the skew removing roller 13 starts to rotate, the suction of the solenoid 44 is stopped to return to the normal retard spring pressure.
[0019]
According to the present embodiment, by providing the skew feeding roller and increasing the nip pressure of the feed roller and the retard roller toward the roller to feed the paper, the abrasion between the separation feeding roller and the paper, the paper Stable skew removal can be performed irrespective of friction or paper type.
[0020]
<Embodiment 3>
In the present embodiment, the feed gear 31 that rotationally drives the feed roller 12 is driven by a pulse motor whose rotation speed is variable. The steps from the sheet feeding command to the separation and feeding are the same as those in the first embodiment, and a description thereof will be omitted.
[0021]
FIG. 9 illustrates a sheet separation state, in which the pickup roller 10 returns to the standby position, and the sheet S is separated and fed by a pair of a feed roller 11 and a retard roller 12, which are sheet separation and feeding means. At this time, the feed roller 11 is driven at the rotation speed v1. FIG. 10 shows the skew feeding state. When the leading end of the sheet S reaches the sheet detection sensor 14, the rotation speed variable motor 7 is rotated at a high speed to increase the speed of the feed roller 11 to push the sheet S against the skew feeding roller. Hit it. When the skew removing roller starts to rotate, the speed of the feed roller is returned to the initial speed. The ratio of the increase speed required for abutting the sheet S against the stopped skew feeding roller for a set time or more is determined by setting the transport speed of the set separation feeding roller to v1 and setting the wear speed of the roller and the paper type. Assuming that the speed at the time of reduction due to the difference is v2, it is v1 / v2 or more.
[0022]
As another embodiment, assuming that the normal stop time of the skew removing roller 13 is Tr1, the minimum guaranteed stop time is Tr2, and the distance Lr between the sheet detection sensor 14 and the skew removing roller is, the rate of speed increase is as follows. , Lr / {Lr * v2 / v10 (Tr1-Tr2) * v2} or more, it is possible to obtain the effect.
[0023]
According to the present embodiment, the sheet is fed without driving the pickup roller 10 by providing the skew feeding roller and increasing the rotation speed of the feed roller toward the roller to feed the sheet. Stable skew removal can be performed regardless of the wear between the feed roller and the paper, the friction between the papers, the paper type, and the like.
[0024]
As a modified example of each of the above embodiments, the elapsed time after a paper feed command by a paper feed command unit (not shown) is measured without providing a detection sensor, the sheet is again fed by the pickup roller after a predetermined set time, and then after a further fixed time The paper can be fed by rotating the skew removing roller.
[0025]
【The invention's effect】
As described above, according to the present invention, the skew feeding roller is provided downstream of the sheet separating / feeding means, and the feeding force of the sheet is increased or the feeding speed is increased before the skew feeding roller is started. By doing so, there is an effect that stable skew removal can be performed.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a paper supply standby state of a paper supply device according to a first embodiment of the present invention; FIG. 2 is an explanatory diagram of a paper supply state of a paper supply device of a first embodiment according to the present invention; FIG. 4 is an explanatory view of a sheet separating state of the sheet supplying apparatus according to the first embodiment of the present invention. FIG. 4 is an explanatory view of a skew removing state of the sheet supplying apparatus of the first embodiment according to the present invention. FIG. 5 is a sheet supplying apparatus of the present invention. FIG. 6 is an explanatory view of a sheet feeding mechanism of the present invention. FIG. 7 is an explanatory view of a sheet feeding apparatus of a second embodiment according to the present invention in a sheet feeding standby state. FIG. FIG. 9 is an explanatory view of a skew removing state of the sheet supply device according to the second embodiment. FIG. 9 is an explanatory view of a sheet supply standby state of the sheet supply device of the third embodiment according to the present invention. FIG. Of the skew-feeding state of the paper supply device of the present invention.
DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 2 ... Paper supply apparatus 10 ... Pickup roller 11 ... Feed roller 12 ... Retard roller 13 ... Skew removal roller 14 ... Paper detection sensor 15 ... Paper guide 16 ... Torque limiter 17 ... Pickup swing arm 18 ... Pickup Cam 40: retard arm 41: retard spring 42: retard spring mounting member 44: solenoid

Claims (6)

The sheet stacked by the first roller is sent out to a retard type sheet separating / feeding unit including the second and third rollers, the feeding of the first roller is stopped, and the sheet is separated by the sheet separating / feeding unit. While feeding the sheet to the next skew feeding roller pair, and the skew feeding roller pair starts rotating after a certain time after the sheet arrives at the roller pair. A sheet feeding device, further comprising a detecting unit for detecting a leading end of a sheet between a pair of skew feeding rollers, and when the detecting unit detects the sheet, the sheet is fed again by a first roller. The sheet stacked by the first roller is sent out to a retard type sheet separating / feeding unit including the second and third rollers, the feeding of the first roller is stopped, and the sheet is separated by the sheet separating / feeding unit. While feeding the sheet to the next skew feeding roller pair, and the skew feeding roller pair starts rotating after a certain time after the sheet arrives at the roller pair. A sheet feeding device which measures an elapsed time after a command is issued by a command means, sends out the sheet again by a first roller after a predetermined set time, and further rotates the skew feeding roller after a predetermined time. A sheet feeding mechanism that conveys the sheet to the next pair of conveyance rollers by a separation feeding unit having a pair of retard separation rollers that also serves as a separation unit and a conveyance unit, and the conveyance roller pair starts rotating after a predetermined time after the sheet arrives in the sheet feeding apparatus is a skew-up rollers, a detecting means for detecting the leading edge of the sheet between the retard separation roller to said skew-up roller pair provided, the sheet is said detected separated by the separation feeding means A sheet feeding device for increasing the conveying force of the separation / feeding unit until the skew feeding roller pair starts to rotate after being detected by the unit. A sheet feeding mechanism that conveys the sheet to the next pair of conveyance rollers by a retard type separation feeding unit that also serves as a separation unit and a conveyance unit, and the conveyance roller pair is inclined when it starts rotating after a certain time after the sheet arrives. In the sheet feeding device which is a take-up roller, the elapsed time after the command by the sheet feeding command means other than the sheet detecting means is measured, and after a predetermined set time, the conveying force of the separation feeding means is increased. A sheet supply device for rotating a skew feeding roller. A sheet feeding mechanism that conveys the sheet to the next pair of conveyance rollers by a retard type separation feeding unit that also serves as a separation unit and a conveyance unit, and the conveyance roller pair is inclined when it starts rotating after a certain time after the sheet arrives. In the sheet feeding device which is a feed roller, an elapsed time after a command by a sheet feeding command unit other than the sheet detecting unit is measured, and after a predetermined set time, the conveying speed of the separation feeding unit is increased. A sheet supply device for rotating a take-up roller. A sheet feeder according to any one of claims 1 to 5, the image forming apparatus characterized by having an image forming means for forming an image on a sheet fed by the paper feeder.

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