JPH0270637A - Paper feeder - Google Patents

Abstract

PURPOSE:To enable transcription to be improved of a paper sheet suppressed from springing its rear end by providing a paper sheet springing-suppressing member extended to a position in the vicinity on surfaces of a sensitive unit, opposed facing to a transcription charger, and in a position in the vicinity between paired paper feed rollers. CONSTITUTION:A paper sheet springing-suppressing member 4 is provided extending in a direction between paired paper feed rollers 12, 12', and the member 4, whose point end side is placed in the bottom between mutually adjacent rollers of roller parts 12a... constituting the one paper feed roller 12, suppresses springing of a paper sheet 30 when it is released from between the paired paper feed rollers 12, 12'. While by providing a paper sheet springing-suppressing member 3 to a position in the vicinity of transcription part 13a from the one side of a side guide part 1, elastically restoring force of the paper 30, when its rear end is detached from the point end side of the paper springing- suppressing member 3, is almost weakened by deflecting it. Thus suppressing the paper 30 from springing its rear end, transcription which no displacement can be performed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to a paper feed commonly used in devices for copying original images onto fed paper, such as electrostatic transfer copying machines and laser printers. This relates to paper devices.

[Conventional technology]

Generally, in copying machines, etc., a drum-shaped photoreceptor (hereinafter referred to as a photoreceptor drum) is uniformly charged, and the surface of the photoreceptor drum is exposed to light reflected from a document.
An electrostatic latent image is formed on the surface of the photoreceptor drum. Toner, which is a coloring agent, is applied to this electrostatic latent image and developed to form a toner image on the surface of the photoreceptor drum.

Near the photoreceptor drum, as shown in FIG. 5, there is a pair of upper and lower guide portions 41 and 42 for guiding the conveyed paper onto the surface of the photoreceptor facing the photoreceptor during transfer charging;
A pair of upper and lower paper feed rollers 44 and 44' that feed paper parallel to the axial direction of the photosensitive drum 43 are provided, and the paper is transferred to paper 50 having a different paper thickness with a basis weight of 50 g/nf to 125 g/m. It is now possible to do this.

The paper 50 described above is sent out toward the photosensitive drum 43 from between the pair of paper feed rollers 44 and 44', and is fed to the guide portion 41 and
After being guided by 42 , the toner image on the surface of the photosensitive drum 43 is transferred onto the paper 50 when the toner image on the surface of the photosensitive drum 43 is transferred onto the paper 50 .

The lower guide portion 42 described above has an angle θ with respect to the horizontal direction.
The paper 50 is conveyed at an angle and pressed onto the surface of the photoreceptor drum 43 to improve the adhesion of the paper 50 to the surface of the photoreceptor drum 43. It is designed to perform good transfer.

[Problem to be solved by the invention]

However, in the conventional paper feeding device described above, the paper 50 is placed in the guide section 42 which is inclined at an angle θ' with respect to the horizontal direction.
In order to be guided and conveyed by the paper feed roller 44
- After separating from the pair 44', an upward elastic restoring force acts on the rear end of the paper 50, and the transfer continues while contacting the upper guide portion 41. Therefore, when the paper 50 separates from the guide section 41, the rear end of the paper 50 springs up due to its elastic force, and the vibrations generated at this time may cause transfer misalignment on the paper 50. In particular, tsubo 1[7
When paper called thick letter paper with a weight of 5 g/nr or more is used, the stiffness of the paper increases, so that the trailing edge of the paper bounces up more, and transfer misalignment becomes more pronounced.

In order to prevent such transfer misalignment, it is conceivable to provide a flexible paper jump prevention member extending from the guide section to a position near the transfer section. As a result, after the paper leaves the guide section, the paper jump prevention member can prevent the trailing edge of the paper from jumping up due to the elastic restoring force of the paper, that is, the stiffness of the paper, making it possible to avoid transfer misalignment to the extent possible. becomes.

However, since the paper is conveyed so as to be pressed against the photoconductor drum, even when the paper leaves the pair of upper and lower paper feed rollers, the trailing edge of the paper springs up due to its elastic restoring force, and at this time, Transfer misalignment occurs on the paper due to vibrations, etc., especially when the basis weight is 75.
When paper called thick letter paper having a rating of g/rrf or more is used, there is a problem in that the trailing edge of the paper bounces up significantly, resulting in a large transfer misalignment.

[Means to solve the problem]

In order to solve the above-mentioned problems, a paper feeding device according to the present invention includes a pair of paper feeding rollers for conveying paper onto the surface of a photoconductor facing a transfer charger, a pair of paper feeding rollers and a surface of the photoconductor that faces the transfer charger. In the paper feed device, the guide section is provided between the upper passages and is provided to guide the paper conveyed from the pair of paper feed rollers from the upper side. The present invention is characterized in that a flexible paper jump prevention member is provided that extends to a position near the surface of the photoreceptor and a position near the pair of paper feed rollers.

[For production]

With the above configuration, when the paper leaves the paper feed roller,
It is possible to prevent the rear edge of the paper from bouncing up due to the elastic restoring force of the paper, that is, the strength of its stiffness, which causes transfer misalignment.Furthermore, when the paper leaves the guide section, it also acts on the rear edge of the paper. The elastic restoring force, that is, the strength of the lower back,
Due to the flexibility of the paper jump prevention member, paper can be fed while being weakened. This makes it possible to prevent the trailing edge of the paper from bouncing up, which would cause transfer misalignment, and to perform good transfer.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

At the top of the copying machine 29, as shown in FIG. 2, a document table 23 on which a document is placed is provided.

Below the document table 23, there are provided a light source 22 for illuminating the document, mirrors 24 for forming an image of reflected light from the document onto the photosensitive drum 13, and a lens 21.

Around the photoreceptor drum 13, there is a static elimination lamp 20 that removes static electricity from the photoreceptor drum 13, a main charger 19 that charges the photoreceptor drum 13, and a lamp that develops an electrostatic latent image formed on the surface of the photoreceptor drum 13 by exposure. a developing tank 17 for transferring the developed toner image onto the conveyed paper 30, a transfer charger 16 for transferring the developed toner image onto the transported paper 30, and a peeling charger 25 for peeling the paper after transfer from the surface of the photoreceptor drum 13.
, and a cleaning device 18 for removing toner adhering to the surface of the photoreceptor drum 13 after transfer.

Further, as shown in FIGS. 1 and 2, the surface of the photosensitive drum 13 facing the transfer charger 16 is a transfer portion 13a where transfer is performed.
On the paper feed side of the paper feed tray 26, 2 is loaded with paper 30 having different paper thicknesses of 50 g/po to 125 g/po.
7 are arranged. Between the paper feed trays 26 and 27 and the transfer unit 13a, there are a pair of upper and lower transport rollers 11 and 11' that transport the paper 30 from the paper feed tray 26, and a pair of upper and lower transport rollers 11 and 11' that transport the paper 30 from the paper feed tray 27 or the above-mentioned transport rollers. Roller 11・
A pair of upper and lower paper feed rollers 12 and 12' are provided parallel to the axial direction of the photoreceptor drum 13, respectively, for conveying the paper 30 from the photoreceptor drum 11' to the lower surface of the photoreceptor drum 13.

As shown in FIG. 1, between the transfer section 13a and the paper feed rollers 12, 12', there is a section for guiding the paper 30 conveyed from the paper feed rollers 12, 12' to the transfer section 13a. An upper guide part l and a lower guide part 2 are provided as guide parts, which are vertically opposed to each other. The lower guide part 2 is arranged at an angle θ with respect to the horizontal direction,
The paper 30 is conveyed at an angle in the feeding direction so as to be pressed onto the surface of the photoreceptor drum 13 to improve the adhesion of the paper 30 to the transfer section 13a and to perform good transfer.

On the lower surface side of the upper guide part 1, there is provided a flexible paper jump prevention member 3 that extends to the vicinity of the transfer part 13a, which is the surface of the photoreceptor facing the transfer charger, and The direction between the pair of paper feed rollers 12 and 12' in this embodiment, in which a flexible paper jump prevention member 4 as a paper jump prevention means is extended in the direction between the paper feed rollers 12 and 12'. The distal end side of the paper jump prevention member 4 extended to
As shown in FIG. 4, the roller portions 12a . This makes it possible to more reliably and smoothly prevent the paper 30 from bouncing up due to its elastic restoring force, that is, its stiffness, and absorb its vibrations.

Further, as shown in FIG. 2, a paper discharge tray 28 for placing the paper 30 after copying is provided on the paper discharge side of the transfer section 13a through which the paper 30 after the transfer is conveyed. In order from the peeling charger 25, a conveyor belt 14 conveys the paper 30 after transfer toward the paper discharge tray 28, and a fixing device 15 that heats and presses the paper 30 sent by the conveyor belt 14 to fix it. , Paper 3 after fixing
A conveyance roller l for discharging 0 onto the paper discharge tray 28
O is provided.

In the above configuration, when copying, the document table 23
rotates the photosensitive drum 13 in the direction of arrow B while moving it in the direction of arrow A with the original placed thereon. As the photoreceptor drum 13 rotates, the surface of the photoreceptor drum 13 is charged as it passes near the main charger 19 and charges are accumulated, and the mirrors 24... and lenses 21
Exposure is performed through the photoreceptor drum 13, and only the exposed portion of the surface of the photoreceptor drum 13 is charged and an electrostatic latent image is formed.

This electrostatic latent image is developed by toner adhering to it when it passes near the developer tank 17.

On the other hand, the paper 30 fed from the paper feed tray 26 or the paper feed tray 27 is transferred to the transport rollers 11, 11', the paper feed rollers 12, 12', and further to the paper feed port.

- From the rollers 12 and 12', the paper is guided by the paper jump prevention member 4, the upper guide section 1 and the lower guide section 2, and the paper jump prevention member 3, and is transported to the transfer section 13a of the photosensitive drum 13. be done.

Here, the paper 30 that was being conveyed so as to be pressed against the transfer section 13a is bent, and this paper 30
When the paper leaves the pair of paper feed rollers 12 and 12', the third
As shown in Figure (a), the rear end of the paper 30 tries to jump up due to its elastic restoring force, but since the rear end of the paper 30 comes into contact with the paper jump prevention member 4 and does not jump up, the transfer misalignment occurs. In addition, since the paper 30 is conveyed along the lower guide portion 2 inclined at an angle θ with respect to the horizontal direction, the paper jump prevention member 4, the paper 30 is conveyed in contact with the upper guide part 1, and when the paper 30 leaves the upper guide part 1, the trailing edge of the paper 30 touches the paper as shown in FIG. 3(b). This makes it possible to prevent the trailing edge of the paper 30 from bouncing up, which would cause transfer misalignment, by coming into contact with the bouncing prevention member 3 . Furthermore, when the trailing edge of the paper 30 advances toward the tip side of the paper jump prevention member 3, the paper jump prevention member 3 becomes easy to bend, and when the trailing end of the paper 30 leaves the paper jump prevention member 3, The elastic restoring force of the paper 30 causes the paper jump prevention member 3
After the trailing edge of the paper 30 leaves the paper jump prevention member 3, the trailing edge of the paper 30 moves to the transfer section without jumping up to cause transfer misalignment. This completes conveying the paper 30 to 13a.

The paper 3o, which has been transferred in the transfer unit 13a, is sent to the fixing device 15 by the conveyance belt 14 and fixed thereon, and then discharged by the conveyance roller 10 onto the paper output tray 28 and placed thereon, while the toner image is After the transfer, residual adhering toner is removed by the cleaning device 18, and static electricity is removed by the charge removal lamp 20 in preparation for the next copy.

In this way, the paper jump prevention member 3 is extended from one side of the upper guide section 1 to the vicinity of the transfer section 13a, and the roller section 12a constituting the paper feed roller 12 is extended from the other side of the upper guide section 1. If the paper jump prevention member 4 is extended to the lower part between the pairs of
When the paper 30 leaves the pair of paper feed rollers 12 and 12', the rear end of the paper 30 does not jump up. ,
Most of the elastic restoring force of the paper 30 is caused by the paper jump prevention member 3
Since it is weakened by bending the paper 3o, it is possible to prevent the trailing edge of the paper 3o from bouncing up, which would cause transfer misalignment.

In this embodiment, the paper jump prevention members 3 and 4 are provided in the upper guide part 1, but this is different from the structure in which the paper jump prevention members 3 and 4 are integrally molded in the upper guide part 1. attached, or upper guide part 1 and paper jump prevention member 3.
4 may be integrally molded.

In addition, in this embodiment, the paper jump prevention member is provided only at the upper guide section 1, but the present invention is not limited to this.
It may also be provided in the lower guide part 2.

〔Effect of the invention〕

As described above, the paper feed device according to the present invention includes a pair of paper feed rollers for conveying paper onto the surface of the photoreceptor facing the transfer charger, and a path between the pair of paper feed rollers and the path on the surface of the photoreceptor. In the paper feeding device, the guide section is provided with a guide section disposed on the paper feed roller pair to guide the paper conveyed from the pair of paper feed rollers from above. In this configuration, a flexible paper jump prevention member is provided, which extends to a position near the pair of paper feed rollers and a position near the pair of paper feed rollers.

This prevents the trailing edge of the paper from jumping up when the paper leaves the pair of paper feed rollers and when the paper leaves the guide section. When the paper leaves the tip side of the paper jump prevention member, most of the elastic restoring force of the paper is absorbed by the paper jump prevention member.
This has the effect of reliably preventing the trailing edge of the paper from bouncing up, which would cause transfer misalignment.

[Brief explanation of the drawing]

1 to 4 show one embodiment of the present invention, in which FIG. 1 is a side view of main parts schematically showing a paper feeding device, and FIG.
The figure is a schematic explanatory diagram showing the general structure of a copying machine, Fig. 3 (a)
is an explanatory diagram of the main parts of the paper feeding device when the trailing edge of the paper leaves the paper feeding roller, and (b) is an explanatory diagram of the essential parts showing the paper feeding device when the trailing edge of the paper leaves the guide section 4 are perspective views of essential parts showing the relationship between the paper feed roller and the paper jump prevention member. FIG. 5 shows a conventional example, and is a side view of a main part schematically showing a paper feeding device. 1 is the upper guide part (guide part), 2 is the lower guide part (guide part)
, 3 and 4 are paper jump prevention members, 13 is a photosensitive drum, 1
3a is a transfer unit, 19 is a main charger, 16 is a transfer charger, 25 is a peeling charger, 11 and 11' are transport rollers, 12 and 12' are paper feed rollers, 12a is a roller unit, 29 is a copying machine, and 30 is a It is paper. Figure (a) Figure (b)

Claims (1)

[Scope of Claims] 1. A pair of paper feed rollers for conveying paper onto the surface of the photoreceptor facing the transfer charger, and a paper feeding roller disposed between the pair of paper feed rollers and a path on the surface of the photoreceptor. In a paper feeding device equipped with a guide section provided to guide the paper conveyed from the roller pair from above, the guide section includes a position near the surface of the photoconductor facing the transfer charger, and a guide section that guides the paper conveyed from the roller pair from above. A paper feeding device characterized in that a flexible sheet jumping prevention member is provided that extends to a position near a pair of paper rollers.