JPH082739A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent generation of a wrinkle or to decrease it, as small as possible, which is caused in the case that an envelope passes through a fixing device, without complicating a constitution of a conveying path. CONSTITUTION:A rotary unit 55, having protruded parts 54, is provided in a conveying guide 51 between a photoconductor and a fixing device, and an envelope 70, fed in a vertical direction, is fed to the fixing device by changing the direction into a horizontal direction. The rotary unit 55 can be vertically moved, and by leaving it as retracted downward from a paper passing surface of the conveying guide 51 at ordinary time, obstructing conveying the other paper is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copying machine, printer,
The present invention relates to an image forming apparatus such as a facsimile.

[0002]

2. Description of the Related Art Generally, in an image forming apparatus such as a copying machine or a printer which uses an electrophotographic method, a sheet fed out one by one from a sheet feeding section is sent to a transfer section to transfer a toner image formed on a photoconductor. After that, the toner image on the paper is fixed by heat and pressure sent to the fixing unit.

[0003]

By the way, in recent years, it is required to form an image not only on a specific sheet but also on various sheets such as postcards, OHPs, recycled paper, etc. It is also desired that the image can be formed on an envelope. It is rare. However, since the envelope is made by bending the paper into a tubular shape, it means that at least two sheets of paper overlap each other, and there is a portion where three to four sheets overlap at the adhesive portion, and a double envelope or the like has a larger number of sheets. A part that extends is also generated.

On the other hand, the fixing device is composed of a heating roller having a heat source therein and a pressure roller which is in pressure contact with the heating roller. Generally, since the heating roller has a structure in which a thin release layer is provided on a rigid body such as aluminum, and the pressure roller has a structure in which an elastic body such as silicon rubber is provided on a rigid body such as aluminum, the heating roller surface is hard. Since the surface of the pressure roller is soft, the heating roller bites into the surface of the pressure roller when both rollers come into pressure contact with each other, and the nip becomes a curved surface in the sheet conveying direction.

When the envelope passes through the nip,
Since the nip has a curved surface, the amount of conveyance may be different between the front and back of the envelope, and the accumulated deviation may appear as wrinkles at the rear end of the envelope.

Since the degree of this wrinkle depends on the amount of deviation of the accumulated transport amount, it is advantageous that the amount passing through the fixing nip, that is, the length is short in order to suppress the occurrence of wrinkles. However, in order to send envelopes in a short length, it is necessary to arrange conveying means such as conveying rollers over the entire length of the conveying path at intervals shorter than the width of the envelope, resulting in a large number of parts and restrictions in designing the conveying path. turn into.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus having a simple structure, which does not cause wrinkles in the envelope or suppresses wrinkling as much as possible.

[0008]

Therefore, the present invention provides an image forming apparatus for fixing an image by passing a material to be transferred holding an unfixed image between a pair of rollers contacting each other at a predetermined pressure. It is characterized in that a means for changing the carrying direction of the transferred material is provided in the carrying guide portion between the fixing means and the fixing means. Further, the means for changing the carrying direction is characterized in that it can be projected and retracted on the carrying guide surface.

[0009]

With the above-described structure, the image forming apparatus of the present invention changes the conveying direction laterally in front of the fixing device even when the envelope is passed, so that the length of passage through the fixing nip can be shortened, and the overall structure of the device can be achieved. Eliminate wrinkles without complicating
Or it can be prevented as much as possible.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of the overall configuration of an electrophotographic apparatus according to the present invention. In the figure, the sheet fed by the sheet feeding roller 20 from the sheet feeding cassette 19 is temporarily stopped in a state where the leading end of the sheet is abutted against the pair of registration rollers 21 which is stopped. Around the photoconductor 12, a charging unit 13, a developing unit 14, a transfer unit 15, and a cleaning unit 16 are arranged in this order in the rotation direction indicated by the arrow, and when the photoconductor 12 rotates in the direction of the arrow, the charging unit 13 causes the charging unit 13 to rotate. The surface is uniformly charged and irradiated with laser light from the optical writing means 18 to form an electrostatic latent image, which is visualized by toner when passing through the developing means 14. The registration roller pair 21 transfers the visible image of the stopped paper to the transfer means 1
The rotation is started so as to reach the transfer portion at the same timing as passing through 5. Then, after this visible image is transferred onto the upper surface of the paper by the transfer means, the conveyance guide plate 51
The fixing device 17 is guided to pass between the heating roller 17a and the pressure roller 17b, and the visible image is fixed. After that, the paper is conveyed to the paper ejection unit by the paper ejection roller pair 24,
The paper is guided by the paper discharge guide 26 and is stacked on the paper discharge tray 27.

By the way, a rotating body 55 having two protrusions 54 is provided on the back side of the sheet passing surface of the transport guide 51. The rotating body 55 is provided so as to be movable up and down by the operation of the control mechanism 56.
It is configured such that it can be projected or settled on the paper passing surface of.

When the envelope 70 is conveyed in this image forming apparatus, the envelope 70 is first fed in the longitudinal direction and a toner image is formed at the transfer portion, and then on the conveyance guide plate 51 as shown in FIG. Stop once. The rotator 55 is normally in the lowered position, and the protrusion 54 is sunk below the sheet passing surface as shown in FIG. 4. However, when it is detected that the envelope 70 has stopped at a predetermined position, the rotator 55 moves up. As shown in FIG. 5, the protrusion 54 projects above the sheet passing surface. And the rotating body 55
When is rotated about 90 °, the envelope 70 is rotated by the protrusion 54 and stops in the state of FIG. After that, the rotating body 55 descends, the protrusion 54 sinks below the sheet passing surface, and the envelope 70 is sent to the fixing device 17 by the transport roller 57.

When the transfer target other than the envelope is conveyed, the protrusion 54 of the rotating body 55 stands by below the sheet passing surface of the conveying guide plate 51 as shown in FIG. There is no obstacle, and the paper to be passed is conveyed in the direction of arrow A by the conveyor belt 58 without any trouble.

In this embodiment, the rotating means is provided only between the transfer portion and the fixing portion. However, if the rotating means is provided downstream of the fixing portion, the conveying direction of the envelope passing through the fixing device is changed again and the longitudinal direction is changed. It is possible to discharge the sheet to a wide area, and it is possible to widen the interval between the conveying means after the fixing device.

[0015]

As described above, the present invention has the following effects. That is, according to the first aspect of the present invention, even when the envelope is passed, since the fixing device can be passed through by changing the conveying direction in the lateral direction, wrinkles can be generated without complicating the constitution of the conveying path. It can be eliminated or prevented as much as possible.

According to the second aspect of the invention, the means for changing the direction is projected on the sheet passing surface of the conveying guide.
Since it is retractable, it does not hinder the passage of other sheets.

[0017]

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an image forming apparatus of the present invention.

FIG. 2 is a plan view (before rotation) of the conveyance guide plate of the present invention.

FIG. 3 is a plan view (after rotation) of the conveyance guide plate of the present invention.

FIG. 4 is a diagram showing a state in which a rotating body is lowered.

FIG. 5 is a view showing a state in which a rotating body is raised.

[Explanation of symbols]

 12 Photoreceptor 15 Transfer Means 17 Fixing Device 17a Heating Roller 17b Pressure Roller 51 Conveying Guide Plate 54 Protrusions 55 Rotating Body 56 Control Mechanism 57 Conveying Roller 58 Conveying Belt 70 Envelope

Claims (2)

[Claims] 1. An image forming apparatus for fixing an image by passing a material to be transferred holding an unfixed image between a pair of rollers which are in contact with each other under a predetermined pressure, and a conveyance guide section between the transfer means and the fixing means. An image forming apparatus, characterized in that a means for changing the conveying direction of the material to be transferred is provided in the. 2. The image forming apparatus according to claim 1, wherein the means for changing the conveying direction is capable of protruding and retracting on the conveying guide surface.