JP2858187B2 - Sheet material transport device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam printer, an electrophotographic copying machine, a printing machine, and a facsimile machine for performing processing such as forming an image on a sheet material such as printing paper, copying paper, printing paper, and facsimile paper. The present invention relates to a sheet conveying apparatus for conveying a sheet to an image forming unit in an image forming apparatus such as the one described above.

[0002]

2. Description of the Related Art FIGS. 4 to 6 show a typical laser beam printer in an image forming apparatus.

[0003] system for linearly conveying the sheet material 100 as shown in FIG. 4 for obtaining the reliability of the conveyance in the image forming apparatus is employed. Further, in order to reduce the installation space, the sheet material 100 as shown in FIGS. 4 and 5
An image forming apparatus of a type in which the transport path is reversed is developed.

On the other hand, in the image forming apparatus includes a sheet feeding cassette 101 which slides in the arrow C direction as shown in FIG. 3
It is necessary to correctly send the sheet material 100 stored in the image forming unit (not shown) to the reference surface 1 of the separation claw 102.
Attempts are being made to improve the printing accuracy and reduce the cost by pressing the end of the sheet material 100 against the sheet 03 by using a sheet feeding roller 104 as a skew feeding roller and performing one-sided conveyance.

[0005]

[SUMMARY OF THE INVENTION However, in one transport device such as shown in FIG. 3, in the case of an image forming apparatus obtained by inverting the conveying path of the sheet material 100, the extension of the shaft of the conveying roller unit E and the conveying roller 105 There is a tendency that a difference in curvature occurs in the path of the sheet material 100 at the non-conveying roller portion on the line (the position on the back side of the conveying roller 105 in the drawing). Transport roller 10
Although it is sufficient to provide the transport guide 106 that accurately matches the outer peripheral surface, the transport guide 106 comes into close contact with the transport roller 105 and blocks the transport path of the sheet material 100, which is not possible.

[0006] By providing the slight clearance fit with the outer peripheral surface of the conveying roller 105, so that the portion A of FIG. 3, 2 from FIG conveying path upstream for passing over the surface of the conveying guide 106 of the sheet 100 There is an inconvenience that an area may enter the roller 107 provided on the image forming apparatus main body side for forming the second nip at an angle equal to or greater than the vertical. As a result, jams, corner breaks, and the like occur in the transport path.

In view of the above, the present invention has been made in view of the above circumstances, and provides an image forming apparatus having a transport path for reversing a sheet material, in which a jam, a corner break, and the like do not occur. It is in.

[0008]

In an image forming apparatus, a bundle of stacked sheet materials is stored in a paper feed cassette, separated into one sheet material, and conveyed and recorded using the end surface of the sheet material as a conveyance reference. In the sheet material transport device, a transport roller that transports the sheet material, a plurality of rollers that follow the transport roller and form a nip that transports the sheet material, including a transport roller portion of the transport roller. A conveyance guide having an arc portion for reversing the conveyance path of the sheet material in the rotation direction of the conveyance roller is provided on a non-conveyance roller portion on an extension of the axis of the conveyance roller, and provided on the non-conveyance roller portion in the nip portion. By making the distance between the conveyance guide and the center of the conveyance roller smaller than the radius of the conveyance roller, a conveyance guide provided with a gap between the conveyance roller and the conveyance roller is provided. Conveying guide more provided on the non-conveying roller unit is characterized in that projecting into the conveying roller center side.

It is preferable that a conveyance guide having arc portions having different radii of curvature is provided on the conveyance roller portion and the non-conveyance roller portion.

[0010]

According to the above construction, the sheet material fed from the paper feed cassette is the first of a plurality of rollers driven by the transport roller and one or more of the rollers driven by the transport roller from the upstream of the transport path formed by one or more rollers. Because of the nip, the transfer roller receives the transfer force, and the transfer guide provided on the non-transfer roller portion protrudes toward the center of the transfer roller from the transfer guide provided on the transfer roller portion. The roller is the second nip from the upstream formed by another roller and the transport roller while pressing the sheet material onto the outer peripheral surface of the transport roller by the transport guide of the non-transport roller portion in the gap of the transport guide of Transported to Then, the sheet is further conveyed to the image forming section via a third nip from the upstream formed by another roller and a conveying roller. Therefore, no jam or corner break occurs in the transport path.

As a conveyance guide having arc portions having different curvature radii on the conveyance roller portion and the non-conveyance roller portion, for example, the curvature radius of the arc portion of the conveyance guide of the non-conveyance roller portion is determined by the radius of curvature of the conveyance guide of the conveyance roller portion. By making the transport roller smaller, the transport guide of the non-transport roller portion protrudes toward the transport roller center side, and along the outer peripheral surface of the transport roller as described above, compared to the sheet material stacked on the sheet feed cassette. The sheet material conveyed one by one can enter the second nip from the upstream of the conveyance path.
Therefore, jams and corner breaks do not occur in the transport path.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a description will be given of an embodiment in which a sheet conveying apparatus according to the present invention is applied to a laser beam printer as an image forming apparatus of a type in which a conveying path of a sheet is reversed. FIG. 1 is a drawing that best illustrates the features of the present invention, and this sheet material conveying device is a one-sided conveying device. 1 and 2, reference numeral 1 denotes a transport roller for transporting the sheet material, and reference numerals 2, 3 and 4 denote driven rollers attached to the transport roller 1 to form a nip for transporting the sheet material.
Is a transport path to a transport roller section E for holding the rollers 2 and limiting the direction of the transported sheet material to a second nip direction from the upstream of the transport path of the sheet material formed by the transport rollers 1 and the rollers 2 Is provided in a state where a necessary space is maintained so as to secure the circular arc portion 5 along the outer peripheral surface of the transport roller 1.
A conveyance roller unit conveyance guide 1 has a roller 3 for holding the rollers 3 and 4 for feeding the sheet material obliquely, and is provided in a conveyance roller unit E for limiting the sheet material conveyance direction to the image forming unit direction (not shown). The second conveyance roller unit conveyance guide 7 stores a bundle of stacked sheet materials and is a detachable paper cassette. Reference numeral 8 denotes a state when the paper cassette 7 is mounted on the laser beam printer main body L, as shown in FIG. Thus, the non-transport roller portion transport guide having the arc portion 81 provided on the sheet feeding cassette 7 which is the non-transport roller portion F in the nip portion on the extension of the axis of the transport roller 1, and the curvature of the arc portion 81 The radius r is smaller than the radius R of the transport roller 1, that is,
When the paper feed cassette 7 is mounted, the distance between the arc portion 81 of the non-conveying roller portion conveying guide 8 and the center of the conveying roller 1 is small, so that the tip of the arc portion 81 protrudes toward the center of the conveying roller 1. (The hatched portion in FIG. 1).

Reference numeral 9 denotes a separation claw for separating the sheet material one by one, reference numeral 10 denotes a paper feed roller for transporting the sheet material to the transport roller unit E, and reference numeral 11 denotes a paper sheet stacked on the paper feed cassette 7. The leaf 12 is provided in the paper feed cassette 7, and is a middle plate on which the paper leaf 11 is loaded, and 13 is a spring interposed between the end of the middle plate 12 and the bottom of the paper feed cassette 7. To bias the paper feed roller 10 side.

The paper cassette 7 and the paper cassette 7
The non-conveying roller section conveyance guide 8 provided above slides in the direction of arrow C shown in FIG. 1 and is detachable.

As shown in FIG. 1, the conveying path of the sheet material is conveyed to a conveying roller section E by a paper feed roller 7 (arrow B _{1 in} FIG. ₁ ), and is attached to the conveying roller 1 and the conveying roller 1. While being obliquely fed by the driven rollers 2, 3, and 4 to the transport reference plane G, the transport path B ₁ is transported to an image forming section (not shown) (arrow B _{2 in} FIG. 1) via a nip formed by the rollers. It has become a ~B _2.

Next, the operation will be described. When a power switch (not shown) is turned on and the driving unit is operated, the paper feed roller 10 is rotated, and the conveyance reference is set by the separation claw 9 from the paper sheets 11 stacked from the paper feed cassette 7, The leaves 11 are separated one by one and sent out to the first transport roller unit transport guide 5. In the first transport roller unit transport guide 5, in the first nip from the upstream of the transport paths B _{1 to} B _{2 formed} by the transport roller 1 and the roller 2, the paper sheet 11 receives a transport force and the first transport roller unit transport guide 5 And non-conveying roller section conveying guide 8 on sheet cassette 7
Is sent along. When the paper sheet 11 rushes into the second nip from the upstream of the transport paths B _{1 to} B _{2 formed by the} transport rollers 1 and the rollers 3, the curvature radius r of the arc portion 81 of the non-transport roller section transport guide 8 is changed by the transport rollers. 1, the radius of curvature r of the arc portion 81 of the non-conveying roller portion transport guide 8 is smaller than the radius of curvature γ of the arc portion 51 of the first transport roller portion transport guide 5. 1 (shaded portion in FIG. 1), the paper sheet 11 is pressed down and follows the outer peripheral surface of the transport roller 1. Then, the sheet is sent to an image forming unit (not shown) via a third nip from the upstream of the conveying paths B _{1 to} B ₂ formed by the conveying roller 1 and the rollers 4 in sequence.

As described above, the sheet conveying apparatus of the present invention performs one-sided conveying, includes the rollers 3 and 4 constituting the nip with the conveying roller 1 and the second conveying roller section conveying guide 6, and performs non-conveying. First, the transport direction of the paper sheet 11 is reversed on the paper feed cassette 7 which is the roller unit F and the transport roller unit E.
A non-conveying roller section conveying guide 8 for providing a conveying roller section conveying guide 5 and one roller 2 for conveying a conveying force at that time, and for aligning the paper sheet 11 on the outer peripheral surface of the conveying roller 1.
With this configuration, the paper sheet 11 is transported along the outer peripheral surface of the transport roller 1 when the paper sheet 11 enters the nip.

[0018] Accordingly, the first conveying roller unit conveyance guide 5 in the folded portion of the sheet 11 in the transport roller unit E, while maintaining the space required for ensuring the transport path B ₁ .about.B _2, paper since the sheet 11 is adapted to be oblique feed conveyed in contact with the conveying roller 1 outer peripheral surface, including the nip, in the transport path B ₁ .about.B _2, jams, eliminates causing breakage corners, also printing accuracy Got better.

When a manual feed section (not shown) is provided in the apparatus, as shown in FIG. 1, the transfer path is the second nip from the upstream in the transfer paths B _{1 to} B ₂ from the arrow B ₁ ′. since that would be sent later in B _2, inconvenience does not occur, it is suitable as a sheet material conveying apparatus for performing the manual paper feed, both cassette feeding.

Also, in FIG. 1, the radius of curvature r of the arc portion 81 of the non-transport roller portion transport guide 8 in the non-transport roller portion F and the radius of curvature of the arc portion 51 of the first transport roller portion transport guide 5 in the transport roller portion E are shown. It is apparent that the same effect can be obtained even when the center of the arc of the arc portion 81 of the non-conveying roller portion conveying guide 8 is set to be lower than the center of the conveying roller 1.

In the above-described embodiment, an example using a one-sided conveying device has been described. However, the present invention can be similarly applied to a device used for a two-sided conveying device having a non-conveying roller portion.

[0022]

As described above, the sheet material conveying device according to the present invention includes a conveying roller, a plurality of rollers constituting a nip, and a conveying guide provided on a conveying roller portion. A non-transport roller provided on the non-transport roller portion and the transport roller portion on an extension of the axis of the transport roller, and a roller for transmitting a transport force at that time, and a non-transport roller for causing the sheet material to follow the transport roller outer peripheral surface And a transport guide provided in the section so that the sheet material is transported along the outer periphery of the transport roller when the sheet material enters the nip.

Accordingly, the sheet material contacts the outer peripheral surface of the conveying roller in a state where the conveying guide of the conveying roller portion in the folded portion of the sheet material is maintained in the conveying roller portion with a gap necessary for securing a conveying path. Since the paper is conveyed obliquely, jamming and corner breakage do not occur in the conveyance path including the nip, and the printing accuracy is improved.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a main part of an image forming apparatus to which a sheet conveying apparatus according to an embodiment of the first invention is applied.

FIG. 2 is a longitudinal sectional view of a main part of FIG. 1;

FIG. 3 is a vertical sectional view of a main part of an image forming apparatus to which a conventional sheet material conveying device is applied.

FIG. 4 is an overall longitudinal sectional view of a conventional laser beam printer of a system for conveying a sheet material linearly.

FIG. 5 is an overall longitudinal sectional view of a conventional laser beam printer of a type in which a sheet material conveyance path is reversed.

FIG. 6 is an overall longitudinal sectional view of a conventional laser beam printer of a type in which a conveyance path of another sheet material is reversed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conveyance roller 2, 3, 4 Rollers 5 1st conveyance roller part conveyance guide 51 Arc part 6 Second conveyance roller part conveyance guide 7 Paper feed cassette 8 Non-conveyance roller part conveyance guide 81 Arc part 9 Separation claw 91 Conveyance reference surface 10 Paper feed roller 11 Paper sheet 12 Middle plate 13 Spring E Transport roller section F Non-transport roller section

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B65H 5/36 B65H 5/06 B65H 29/22 B65H 29/52

Claims (2)

(57) [Claims] 1. A sheet conveying device in an image forming apparatus for storing a bundle of stacked sheet materials in a sheet feeding cassette, separating the sheet into one sheet, and conveying and recording the sheet based on an end surface of the sheet as a conveying reference. A transport roller that transports the sheet material, and a plurality of rollers that follow the transport roller and form a nip that transports the sheet material, comprising a transport roller portion of the transport roller and the transport roller. A conveyance guide having an arc portion for reversing a conveyance path of a sheet material in a rotation direction of the conveyance roller is provided on a non-conveyance roller portion on an extension of a shaft, and a conveyance guide provided on the non-conveyance roller portion in the nip portion; By making the distance to the center of the transport roller smaller than the radius of the transport roller, the transport guide provided in the transport roller portion with a gap between the transport roller and the non- A sheet material conveyance device, wherein a conveyance guide provided in a feeding roller portion protrudes toward a center of the conveyance roller. 2. The sheet conveying apparatus according to claim 1, wherein a conveying guide having arc portions having different radii of curvature is provided on the conveying roller portion and the non-conveying roller portion.