JP2003201053A - Paper conveying guide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems where paper heated and pressurized by a heat roller and a press roller to have a fixed toner image is bent and deformed by the heat and pressure and ejected with a curl produced, in a fixing device of an image forming device that comprises the heat roller, the press roller connected to the heat roller by pressure, and a pair of ejection rollers for ejecting the paper on the downstream side of the press roller. <P>SOLUTION: An ejection port 10b of the fixing device is provided with a paper conveying guide 12 having a plurality of projecting pieces 12f and 12f and projecting pieces 12g, 12g, etc. The projecting pieces 12f and 12f and projecting pieces 12g, 12g, etc., are projected above a nip part between the ejection rollers 15 and 16. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a paper conveying guide provided at an outlet of a fixing device of an image forming apparatus for fixing a toner image transferred on a paper by heat and pressure.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a facsimile machine, the surface of a photoconductor drum is charged by a charger and L
An ED head writes an electrostatic latent image on the surface of the photosensitive drum, and a developing unit superimposes toner on the electrostatic latent image to make it visible, and the photosensitive drum and a transfer roller provided opposite to the photosensitive drum. When a sheet is conveyed between the transfer roller and the transfer roller and a potential of several hundred to several thousand volts having a polarity opposite to that of the toner is applied to the transfer roller, a uniform electric field formed between the photosensitive drum and the transfer roller is generated. The toner is moved from the photoconductor drum to the paper to perform the transfer. The sheet after transfer is conveyed to a fixing device, where the sheet is pressed against a heat roller by a press roller, and the toner transferred on the sheet is heated and melted by the heat roller to be fixed. Then, the sheet is delivered to a pair of ejection rollers arranged on the downstream side of the heat roller and ejected from the ejection port.

[0003]

However, in the above-mentioned prior art, the paper on which the toner image is fixed by being heated and pressed by the heat roller and the press roller is curved by the heat and pressure. There is a problem that the sheet is deformed and discharged in a so-called curled state.

[0004]

The problem to be solved by the present invention is as described above, and the means for solving this problem will be described below. First, as described in claim 1,
Each of the discharge rollers includes a heat roller, a press roller that is in pressure contact with the heat roller, a pair of discharge rollers that discharges the paper on the downstream side thereof, and a paper conveyance guide that guides the paper toward the discharge roller pair. In a fixing device of an image forming apparatus composed of a plurality of roller bodies arranged coaxially,
In the paper conveyance guide, between the respective roller bodies of the discharge rollers and outward of the outermost roller body in the axial direction, projecting pieces protruding from one side of the paper conveyance surface toward the discharge roller pair to the other side. To provide. As a result, the ejected paper sheet is nipped at a plurality of places by the plurality of roller bodies of the ejection roller pair, the nipping portion becomes a “valley”, and the portion raised by the protrusion is “mountain-shaped”. , It is discharged in a wavy state. By making the paper corrugate in this way, it is in a rigid state, so to speak, and curling is prevented.

Further, as described in claim 2, at least two of the protrusions are formed in a mountain shape in a front view. This chevron-shaped protrusion lifts up the paper nipped by the roller body in a wavy state, and when the paper is skewed, the chevron-shaped projection is applied to one side of the paper without restricting the paper. The inclined surface of the protruding piece guides and allows a certain amount of skew, and prevents the discharged sheet from being scratched, such as the edge of the sheet.

Further, as described in claim 3, all of the projecting pieces are formed in a mountain shape in a front view. Further, when the sheet is skewed, the mountain-shaped protrusions guide the one side of the sheet by the inclined surface of the mountain-shaped protrusion, and the sheet is skewed to some extent. While preventing the paper from being damaged, it prevents the paper from being scratched, such as being broken.

[0007]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will now be described with reference to a facsimile machine 1. In the following description, it is assumed that the direction of arrow A shown in FIG. 1 is the front (front side) of the facsimile apparatus 1 and the front, rear, left, and right positions of each structure are described. The front, rear, left, and right positions of each structure in the other drawings also follow those in FIG.

FIG. 1 is an overall perspective view of the facsimile device 1. The main body of the facsimile device 1 is mounted and fixed on a paper feeding device 5, and the image reading device 3 and an image forming device are installed in the main body. The image recording devices 4 of FIG. An automatic document feeder (hereinafter referred to as "ADF") 6 is attached above the image reading device 3, and an exterior cover 21 is provided in front of the ADF 6 so as to be openable and closable with respect to the main body of the facsimile device 1. An image recording device 4 is attached to the.

FIG. 2 is a side sectional view of the image recording device 4. The image forming device 4 comprises an optical writing means such as an LED head 7, a developing unit 8, a photoconductor unit 9 and a fixing unit 10. The image information is transferred to the sheet taken from the sheet feeding device 5 and fixed.

The fixing unit 10 includes a heat roller 13 containing a halogen lamp as a heat source, and a press roller 14 arranged to face the heat roller 13.
Equipped with discharge rollers 15 and 16 arranged at the discharge port 10b on the downstream side (rear side) of the press roller 14 and the sheet conveying guide 12 according to the present invention which is attached to the discharge port 10b. The paper is fed while being pressed against the heat roller 13, and the toner image transferred onto the paper is heated and melted by the heat roller 13 to be fixed. After fixing, the sheet is conveyed by the guide 12
Is discharged by the discharge rollers 15 and 16 while being bent in a laterally (widthwise) wavy state, and discharged onto the discharge tray 22. In addition, the discharge rollers 15 and 16
Are each composed of a plurality of roller bodies 15a, 15a15a and roller bodies 16a, 16a, 16a.

Next, the structure of the transport guide 12 will be described. FIG. 3 is a side sectional view of the paper transport guide 12, and FIG. 4 is a front view of the paper transport guide 12. The paper transport guide 12 is a member formed to have substantially the same width as the casing 11 of the fixing unit 10, and the rear portion of the casing 11. It is attached below. Reference numerals 17 and 17 shown in FIG. 2 denote fixing bolts for fastening both side portions of the transport guide 12 and the casing 11. As shown in FIGS. 3 and 4, the upper portion of the transport guide 12 is cut out at three locations, that is, the central portion and the left and right side portions, so that the roller bodies 16a and 16a of the discharge roller 16 on the lower side are cut out.
-The arrangement space 12a, 12a, 12a of 16a is provided. The upper surface of the transport guide 12 serves as a guide surface for transporting a sheet, and the rear side is formed into a horizontal flat surface 12b, while the front side is formed into an inclined surface 12c inclined downward from the flat surface 12b. A plurality of projecting pieces 12f, 12g, ... And ribs 12h, 12h ,.

The projections 12f and 12f are formed in a mountain shape when viewed from the front, and are provided in the convex portions 12d and 12d on the outer sides of the left and right arrangement spaces 12a and 12a, respectively, and each have a width of approximately A4 size ( The shorter side length) is arranged at intervals. Projection piece 12g 12g ... and rib 12h
.. 12h ... is erected perpendicularly to the inclined surface 12c of the conveyance guide 12, and the protrusions 12g. 12g .. are substantially central to the convex portions 12e, 12e between the arrangement spaces 12a, 12a, 12a. Projecting piece 12f in the convex portions 12d and 12d
・ A total of four are provided on the outer side of 12f. on the other hand,
The ribs 12h, 12h, ... Are provided in total of eight, three on the inner sides of the protrusions 12g, 12g of the protrusions 12e, 12e and one on the outer sides.

The upper ends of the protrusions 12f and 12g both project from the nip portion of the heat roller 13 and the press roller 14 toward the nip portion of the discharge rollers 15 and 16 and above the sheet conveying surface. Although described in detail later, it mainly plays a role of corrugating the paper. On the other hand, rib 12
h is formed to be lower than the protruding pieces 12f and 12g, and forms the sheet conveying surface at the upper end of the rib 12h.
12h ... reduces the frictional resistance by reducing the contact area of the paper with the upper surface of the transport guide 12. The protrusions 12f, 12g ... and the ribs 12h, 12h.
.. The number of arrangements and arrangement configuration are not limited to this configuration. In addition, the mountain shape of the protrusion 12f is not limited to the triangular shape as in this example, but the surface on the center side of the protrusion 12f has an arc shape protruding outward, an arc shape protruding inside, or a trapezoidal shape. It may be formed on an inclined surface that rises as it goes to the outside,

The above is the configuration of the transport guide 12 according to the present invention, and its operation and effect will be described below. The sheet passing through the fixing unit 10 is fed while being pressed by the heat roller 13 by the press roller 14 and is heated and pressed to fix the toner image. The heat and pressure at this time cause the paper to be deformed so as to be curved, so that a so-called curl occurs. In particular, to heat and pressurize the paper uniformly,
With the heat roller 13 formed in a drum shape, the paper is more significantly curved as a result of being along the outer peripheral surface thereof.

In the present invention, the curving paper is
Curling is prevented by waviness in the lateral direction (width direction) by the transport guide 12, and the sheet is discharged to the discharge tray 22. Specifically, as shown in FIG. 5, the ejected paper is three pairs of roller members 15a.
.. are nipped at the central portion and on both side portions, and the nipping portion serves as a "valley".
The portions that are raised from the nip portion by the 2f and 12f and the protruding pieces 12g and 12g ... Are “mountains” and are discharged in a wavy state. By forcing the paper to undulate in this manner, it is in a rigid state and curling is prevented. The deformation to the wavy state is also temporary, and the sheet is restored to the original thin plate shape after being discharged.

In particular, the protrusions 12f and 12f act effectively when ejecting A4 size paper, and even if the size of the paper is skewed at the ejection port 10b, it is ejected with some left and right blurring allowed. To be done. Since the positions of the protrusions 12f and 12f are directly outside the nip portions of the roller bodies 15a and 16a on both the left and right sides, both sides of the A4 size sheet are “valley” to “mountain”. It hits the rising position toward.

As shown in FIG. 6, the projection 12f.
If the protrusions 12g and 12g vertically arranged on the inclined surface 12c of the conveyance guide 12 are disposed at the position 12f, when the sheet is skewed, one side of the sheet, In particular, after the tip comes into contact with the inner surface of the protruding piece 12g and is conveyed while being caught, the paper may be scratched due to edge breakage or the like.

Therefore, at this position, as shown in FIG. 5, the mountain-shaped protrusions 12f and 12f are arranged so that even when the sheet is skewed, one side of the sheet is an inner slope of the protrusion 12f. While being smoothly guided by, it is ejected while allowing some skew. In this way, scratches such as folds of the ejected paper are prevented.

In addition to the A4 size paper which is most frequently used, for example, in the case of B5 size paper, both ends thereof are nipped by the roller bodies 15a. Also, B4 size and A
For 3 size paper, roller bodies 15a and 16 on both left and right sides
Since there are no "valleys" on the outside of a ..., Both sides of the a are floated obliquely upward by the protruding pieces 12f, 12f, and are conveyed without being caught by the outermost protruding pieces 12g, 12g.

[0020]

With the above-described structure, in the three inventions, the discharged paper is nipped at a plurality of places by a plurality of rollers of the discharge roller pair, and the nipped portion is a "valley". Thus, the portion that is raised from the nip portion by the projecting piece becomes a “mountain” and is discharged in a wavy state. By making the paper wavy like this,
In other words, it becomes rigid and curling is prevented. Further, in the chevron-shaped protrusion of the invention according to claim 2 or 3, when the paper is skewed, one side of the paper is inclined with respect to the chevron-shaped protrusion without restricting the paper. The surface guides and allows a certain amount of skew, and prevents the discharged paper from being scratched, such as being broken.

[Brief description of drawings]

FIG. 1 is an overall perspective view showing a facsimile device 1.

FIG. 2 is a side sectional view of the image recording device 4.

FIG. 3 is a side sectional view of the paper transport guide 12.

FIG. 4 is a front view of the paper transport guide 12.

FIG. 5 is a side sectional view of the paper conveyance guide 12 showing a state in which the paper is skewed.

FIG. 6 is a side cross-sectional view of the paper transport guide 12 illustrating a problem when the paper is skewed.

[Explanation of symbols]

1 Facsimile machine 4 Image recording device 10 fixing unit 12 Paper transport guide 12f protrusion 12g rib 13 Heat roller 14 Press rollers 15 Discharge roller 16 discharge roller

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H033 AA15 BA10 BA12                 2H072 CA01 CB06 JA04                 3F053 HA03 HB12 LA05 LB03

Claims (3)

[Claims] 1. A heat roller, a press roller that is in pressure contact with the heat roller, a pair of discharge rollers that discharges the paper downstream thereof, and a paper transport guide that guides the paper toward the discharge roller pair. In the fixing device of the image forming apparatus, in which each discharge roller is composed of a plurality of roller bodies arranged coaxially, in the paper conveyance guide, between the roller bodies of the discharge rollers and the outermost roller body in the axial direction. A paper conveyance guide, characterized in that a projection piece is provided on the outer side, the projection piece protruding from one side of the paper conveyance surface toward the discharge roller pair to the other side. 2. The at least two projecting pieces of the projecting pieces are formed in a mountain shape in a front view.
The paper transport guide described. 3. The paper transport guide according to claim 1, wherein all of the projecting pieces are formed in a mountain shape in a front view.