JPH0412038Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a feeding device for feeding paper used in copying machines, printers, and the like.

[Prior art and its problems]

Various paper feeding devices have been proposed in the past. FIG. 7 is a main part configuration diagram showing an example thereof. In the figure, a paper loading plate 3 is urged upward by a spring 4 from below in a cassette 2 in which a large number of sheets of paper 1 are stacked. Further, the stacked sheets 1 are restricted from moving upward beyond a predetermined position by a separating claw 5 provided at the front end in the feeding direction. On the other hand, the feed roller 6 has a so-called half-moon shape with a part of its circumference cut out in a straight line, and is fixed to a shaft 7 that is rotationally driven via a one-turn clutch by a drive mechanism (not shown). There is. In addition, the feeding roller 6
is stopped with its half-moon-shaped surface facing the paper 1 when not being fed. In a feeding device having such a configuration,
By rotating the half-moon-shaped feeding roller 1 once, the paper is fed by a predetermined length until it reaches the next feeding roller (for example, a pair of standby rolls).

However, in such conventional feeding devices,
Since paper feeding must be completed in one rotation of the half-moon roller, it is necessary to provide another feed roller nearby, making the device complicated. Furthermore, if the feed roller is installed at a position where there is not enough room for the feed roller, slips may occur when feeding thick paper or under low humidity conditions, resulting in paper feeding errors and jams. Furthermore, the diameter of the rollers had to be increased in order to provide some margin for the amount of feed, which was undesirable in terms of space. Furthermore, the load fluctuation at the initial stage of paper feeding is large, which causes image blurring when used in an image forming apparatus.

[Purpose of invention]

In view of the above-mentioned conventional drawbacks, the present invention increases the amount of conveyance without increasing the roller diameter of the feed rollers, and allows feeding with sufficient margin even when feeding cardboard and in low humidity conditions. It is an object of the present invention to provide a feeding device that can alleviate torque fluctuations at the start of paper feeding.

[Key points of the idea]

In order to achieve the above-mentioned object, the present invention provides a feeding device including a paper placement plate on which paper is placed and a feeding roller having a cross-sectional shape in which a part of the circumference is cut out. A shape that is rotatably supported on the rotation shaft of the feed roller, and whose maximum radius is smaller than the radius of the circular portion of the feed roller, and that exceeds the distance between the recessedmost part of the notch of the feed roller and the rotation axis. Equipped with
The present invention is characterized in that it includes an auxiliary rotating member that rotates at a higher circumferential speed than the feeding roller.

[Example of idea]

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a cross-sectional view of essential parts showing the feeding device of the present invention, FIGS. 2 and 3 are side views showing the feeding state, and FIG. 4 is an image forming apparatus using the feeding device of the present invention. FIG.

In FIG. 4, the image forming apparatus includes a charger 11 that uniformly charges the surface of the photoreceptor drum 10 disposed around the photoreceptor drum 10, an optical head 12 that prints according to external recorded information, and a photoreceptor belt. A developing device 13 that develops the electrostatic latent image on the drum surface with toner, a timing roll 14 that feeds paper according to the image position on the photoreceptor drum, and 1 sheet that feeds paper from a cassette.
A feeding roller 15 for taking out sheets one by one, a reversing guide 16,
A transfer device 17 that transfers the toner image on the photoreceptor drum 10 onto paper, a cleaner 18 that removes untransferred toner on the photoreceptor drum, a cassette 19 in which a large number of papers are stacked, and a fixer that heats and fixes the toner image on the paper. It is composed of a roll 20, a conveyance roller 21 that conveys the paper, a discharge roller 22 that discharges the paper to the outside of the machine, and the like.

Next, the operation of the image forming apparatus configured as above will be explained. The surface of the photoreceptor drum 10 is charged by a charger 11 that uniformly charges an electrostatic charge by corona discharge or the like. The photoreceptor drum 10, which is uniformly electrostatically charged, is exposed to light by an optical head 12 that forms an optical image in accordance with recorded information from the outside, thereby forming an electrostatic latent image. The electrostatic latent image thus formed is developed with toner by the developing device 13 and becomes a visible image. On the other hand, the leading edge of a large number of sheets stacked in the cassette 19 is conveyed to the position of the timing roll 14 while coming into contact with the reversing guide 16 by one rotation of the feeding roller 15. At this time,
If a slip occurs in the feeding roller 15 or if there is not enough margin in the feeding amount of the roller, it may cause a paper feeding error or a jam. Furthermore, there is a contradiction in that if the diameter of the rollers is increased in order to provide a margin for the feed amount, the space occupied by the paper feeding device becomes larger.
A toner image is transferred by a transfer device 17 to a sheet (not shown) that is conveyed by a timing roll 14 in synchronization with the image on the photoreceptor drum 10 . The paper onto which the toner image has been transferred is conveyed on the guide plate to the fixing roll 20 position, where it is fixed by being pressed by a pair of heated rolls. The paper with the toner image fixed thereon is transferred to the transport roller 21 and the ejection roller 2.
2 and is discharged outside the machine.

Next, the feeding device of the present invention will be explained. FIG. 1 is a sectional view of a main part of the feeding device, and FIG. 2 is a side view thereof. In the figure, the feed roller 15 has a half-moon shape with a part cut out in a straight line, and a rubber belt 23 is attached to the outer periphery, and a dowel pin or the like is attached to a feed shaft 24 that is rotationally driven by a drive mechanism (not shown). Fixed. The feed roller 15a has substantially the same shape as the feed roller 15, has a rubber belt 23 attached to its half-moon outer periphery, and is fixed to the paper feed shaft 24 with a dowel pin or the like. Furthermore, feeding roller 1
A gear 25 is integrally formed on the side of 5a. On the other hand, the auxiliary roller 26 is connected to the feeding roller 15.
It has a half-moon shape similar to that of , and has a slightly smaller radius, and a rubber belt 27 is attached to the outer periphery. Further, a gear 28 is integrally formed on the side portion and is rotatably supported on the paper feed shaft 24, and its movement to the side is restricted by flanges 29a and 29b. Furthermore, a shaft 32 is attached to a holder 31 hanging down from a stay 30 fixed to the main body of the device (not shown).
is rotatably supported, and gears 32 and 33 are fixed to both ends, respectively. As shown in FIG. 1, the gear 25 is connected to the gear 33 and the gear 2.
8 are in mesh with the gears 32, respectively.

In this embodiment, the numbers of teeth of gears 25, 26, 32, and 33 are z=27, z=18, z=27, and z=36, respectively.
It is. Therefore, when the feed rollers 15, 15a fixed to the paper feed shaft 24 make one rotation, the auxiliary roller 26
Rotate twice.

Next, the operation of the feeding device configured as above will be explained with reference to FIGS. 2 and 3. Rotation is started from a paper feed shaft 24 connected to a drive mechanism (not shown) in response to a paper feed signal from a control system (not shown). Here, the feeding rollers 15, 15a and the auxiliary rollers 26 are stopped with their planar notched surfaces facing down (opposing the sheets 34), so that the topmost sheets of the sheets 34 stacked in the cassette 19 are The paper is spaced apart from the other paper. The auxiliary roller 26 rotates at twice the speed of the feeding rollers 15 and 15a, and as shown in FIG. 34 and starts feeding. After that, the normally rotating feeding roller 1
The rubber belts 23 of 5 and 15a come into contact with the paper 34 and enter a full-scale feeding state. In this state, the roller diameters of the feeding rollers 15, 15a are larger than the diameter of the auxiliary roller 26, so the auxiliary roller 26 rotates without contacting the paper. Next, as shown in FIG. 3, when the feeding roller 15a finishes the paper feeding operation and the cut out flat part begins to face the paper 34, the auxiliary roller 26 rotating at double speed comes into contact with the paper again. The feeding operation is continued until the rotation is completed. Therefore, before the feeding rollers 15, 15a contact the paper at the start of feeding, and after leaving the paper just before the end of rotation, the auxiliary roller 26
Since the rollers feed the paper, even if the auxiliary rollers have the same diameter, they can be fed with sufficient margin.

FIGS. 5 and 6 show other embodiments of the present invention. In this embodiment, a lever 35 which also rotates at twice the speed is provided in place of the auxiliary roller 26 described above.

Even with the above configuration, it is possible to feed extra paper using the lever 35 at the start and end of paper feeding.

Incidentally, in the above embodiment, an example in which the feeding device is applied to an image forming apparatus such as a printer has been described, but the present invention is not limited to this and can of course be applied to other devices that feed sheets one by one. be.

[Effect of idea]

As described above in detail, the feeding device of the present invention can prevent misfeeds and jams caused by slipping of the feeding rollers. Furthermore, since the small-diameter auxiliary rollers contact the paper first, load fluctuations during feeding are small, and transfer blur and image blur can be prevented. Furthermore, since an auxiliary roller that rotates at twice the speed is provided, there is no need to increase the diameter of the roller in order to provide a margin for the feed amount, and space can be saved. Also, there is less time loss due to slips. The drive of the auxiliary roller is also simple, since the drive is taken directly from the feed roller, eliminating the need for a mechanism such as a clutch.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of essential parts showing an example of the present invention, FIGS. 2 and 3 are side views showing the feeding device, and FIG.
The figure shows a configuration diagram of an image forming apparatus to which the present invention is applied;
FIGS. 5 and 6 are side views showing other embodiments of the present invention, and FIG. 7 is a diagram showing the main part configuration of a conventional example. 1...Paper, 2...Cassette, 3...Paper placement plate, 4...Spring, 5...Separation claw, 6...Feeding roller, 7...Shaft, 10...Photoconductor drum, 11... …
Charger, 12... optical head, 13... developer,
14... Timing roll, 15, 15a... Feeding roller, 16... Reversing guide, 17... Transfer device,
18...Cleaner, 19...Cassette, 20...
Fixing roll, 21...Transportation roll, 22...Ejection roll, 23, 27...Rubber belt, 24...Paper feed shaft, 25, 32, 33...Gear, 26...Auxiliary roller, 28...Gear, 29a , 29b... Tsuba, 3
0... Stay, 31... Holder, 32... Shaft,
34...Paper, 35...Lever.

Claims (1)

[Claims for Utility Model Registration] (1) In a feeding device comprising a paper mounting plate on which paper is placed and a feeding roller having a cross-sectional shape in which a part of the circumference is cut out, A shape that is rotatably supported on the rotation shaft of the feed roller, and whose maximum radius is smaller than the radius of the circular portion of the feed roller, and that exceeds the distance between the recessedmost part of the notch of the feed roller and the rotation axis. A feeding device comprising: an auxiliary rotating member that rotates at a higher circumferential speed than the feeding roller. (2) The feeding device according to claim 1, wherein the rotational speed of the auxiliary rotating member is an integral multiple of the rotational speed of the feeding roller. (3) The feeding device according to claim 1, wherein the cross-sectional shape of the auxiliary rotating member is substantially the same as the cross-sectional shape of the feeding roller.