JP2001005328A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent wrinkles caused by carrying of recording paper subjected to fixing, by providing elastic guide members for guiding a recording paper, which are arranged at plural positions on the downstream side of a fixing means in the direction of the width of a carrying path. SOLUTION: Elastic guide members 108A-108D, whose one ends are fixed to the frame body 109 of a fixing device, are provided at four positions, that is, between lower separation claws 107A-107C and at both ends. In a paper ejection mode (a), the top part 1081, as a guide part of each of the elastic guide members 108A-108D is in a position slightly higher than a projection 1071 and guides a recording paper P. In the case of inverting paper ejection or carrying to a carrying path for double-sided image formation, the recording paper P is guided while bent downward as shown by the arrow P3, the top part 1081 becomes almost equal in height to the projection 1071. In either case, the recording paper P is carried with an almost straight shape retained in the direction of the width of the carrying path and flexure is therefore prevented. In the ejected recording paper P, a wavy wrinkle, which has been conventionally produced, is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to a technique for guiding a recording sheet near a fixing unit of the image forming apparatus.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine or a printer using an electrophotographic system, a toner image formed on an image forming body such as a photoreceptor is transferred onto a recording sheet and then fixed on a recording sheet by a fixing means. Has been established.

FIG. 1 is a front view of a conventional fixing device. In the fixing device 100, an upper roller 101, which is a heating roller having a heat source 103 such as a halogen lamp, and a lower roller 102, which is a pressure roller, are provided in pressure contact with each other. A roller 104 that applies the anti-offset agent supplied from the anti-offset agent supply device 105 is in contact with the peripheral surface of the upper roller 101. The recording paper P on which the toner image has been formed enters between the upper roller 101 and the lower roller 102 rotating as shown by the arrow, as shown by the arrow P1, and the recording paper P
The toner image is heated in the process of being conveyed while being held between the lower roller 102 and the upper roller 101 and is thermally fixed on the recording paper P. The recording paper P on which the fixing is completed is an elastic member S, and the upper roller 1
01, the upper separation claws 106A, 106B
It is transported while being guided by 106C and lower separation claws 107A, 107B, 107C.

After passing between the upper roller 101 and the lower roller 102, when the leading end of the recording paper P bends downward, wrinkles are generated on the recording paper P.
The paper ejection direction is slightly guided upward by a convex portion 1071 formed on each of the sheets 07B and 107C. As described above, the convex portions 1071 formed on the lower separation claws 107A, 107B, and 107C prevent the recording paper P from bending after passing through the rollers, thereby preventing wrinkles from being formed on the recording paper.

In an image forming apparatus having a double-sided image forming function and a function of inverting and ejecting recording paper, a conveying roller 110 and rollers 111 and 11 are provided downstream of the fixing unit.
2, a conveyor belt 113 is provided.
Further, a transport switching lever 114 is provided on a transport path formed by the transport rollers 110 and the rollers 111. The transport switching lever 114 is provided rotatably around a shaft 116. When the transport switching lever 114 is at the solid line position, the recording paper P
The paper advances straight as indicated by 2 and is discharged outside the machine. When the transport switching lever 114 moves to the position indicated by the dashed line, the recording paper P is guided by the transport switching lever 114 and advances as shown by the arrow P3, and the transport belt 113 and the transport roller 115 are moved.
And is conveyed downward by the reversing roller 118. When the recording paper P is turned over and discharged, the rotation direction of the reversing roller 118 is reversed at the time when the rear end of the recording paper P reaches just upstream of the reversing roller 118, and the guide member (not shown) The recording paper P is conveyed as shown by an arrow P4 and discharged out of the apparatus. Further, in the double-sided image formation, the recording paper P having the toner image formed on the surface is conveyed by the conveyance switching lever 114 located at the position of the one-dot chain line as shown by the arrow P3, as in the case of the above-described reverse discharge. The sheet is conveyed downward by a reversing roller 118 and sent to a not-shown double-sided forming conveyance path.

[0006]

FIG. 2 shows the upper separating claw 106.
A, 106B, 106C, and lower separating claws 107A, 107
4 shows the state of the recording paper P guided and conveyed by B and 107C in the conveying path width direction.

[0007] As shown in FIG.
A, 107B, and convex portions 1071 respectively formed on 107C
By supporting and guiding the recording paper P, the bending of the recording paper is prevented to some extent. However, bending occurs at both ends of the recording paper as indicated by PB. It has been found that this bending causes an undesired phenomenon that the recording paper P is deformed in a wavy manner as shown in FIG. 3 and remains on the discharged recording paper P as wavy wrinkles. For example, 45kg
When A3 size recording paper or A4 size recording paper is transported in a landscape orientation (the transport path width direction is taken as a long side) with relatively thin paper, such as paper, a downward bending as shown in FIG. The generation of wrinkles due to waving as shown in FIG. 3 is remarkably observed.

In order to prevent such wrinkles from occurring, it is conceivable to increase the height of the convex portion 1071 of the lower separating claws 107A, 107B, 107C to guide the recording paper P upward to some extent. However, an undesired phenomenon occurs such that a strong force acts locally on the recording paper P from below to cause irregularities on the recording paper P. In particular, such a phenomenon is remarkable when the recording sheet P is guided and conveyed to a conveyance path bent downward as in the case of the above-described reverse discharge and double-sided image formation. There is also a means of increasing the number of lower separation claws, but such a means is not preferable in relation to the lower roller 102. Further, the separation claw is a replacement part, and increasing the number of replacement parts is not preferable for maintenance.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent wrinkles as described above which occur due to conveyance of a recording sheet after fixing.

[0010]

The object of the present invention is as follows.
This is achieved by any of the following inventions.

(1) Fixing means for heating the toner image while fixing the toner on the recording paper while transporting the recording paper in contact with the recording paper carrying the toner image, and a fixing device in the width direction of the conveying path downstream of the fixing means. An image forming apparatus, comprising: an elastic guide member arranged at a plurality of positions to guide recording paper.

(2) The fixing means includes an upper roller and a lower roller for nipping and transporting the recording paper, and a separating claw for contacting the upper roller and the lower roller to separate the recording paper is provided. (1) wherein the separation claw that contacts the lower roller guides the recording paper together with the elastic guide member.
Item 10. The image forming apparatus according to item 1.

(3) The image forming apparatus according to the above (1) or (2), wherein a heating means is provided in the upper roller.

(4) The image according to any one of (1) to (3), wherein a conveyance path switching means for switching a conveyance path of the recording paper is provided downstream of the elastic guide member. Forming equipment.

(5) When the recording paper is conveyed by switching the conveyance path by the conveyance path switching means, the time when the recording paper is conveyed on one conveyance path and the time when the recording paper is conveyed on the other conveyance path are different. The image forming apparatus according to (4), wherein a guide portion of the elastic guide member is displaced.

(6) The image forming apparatus according to any one of (1) to (5), wherein the elastic guide member is made of a material having elasticity.

(7) The above (1) to (6), wherein the elastic guide member is constituted by a displaceable guide portion and an urging portion for urging the guide portion with an elastic material. The image forming apparatus according to claim 1.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to an embodiment of the present invention will be described below with reference to FIGS.

FIG. 4 is a diagram schematically showing an image forming apparatus according to an embodiment of the present invention.

In FIG. 1, reference numeral 10 denotes an image forming unit for forming an image on a recording paper by an electrophotographic system; 20, an original reading unit for reading an image of an original and outputting image data;
Reference numeral denotes a post-processing unit that performs post-processing such as sorting, stapling, and punching on the recording paper discharged from the image forming unit 10.

The image forming section 10 has a photoreceptor 11, an image forming means 12 for forming a toner image on the photoreceptor 11 by charging, exposing, and developing, and transferring the toner image on the photoreceptor 11 to recording paper. Transfer unit 17, paper feed units 13 a, 13 b, 13 c, 13 d for storing recording paper on which an image is formed and conveying the recording paper toward image forming unit 12, recording paper reversing and conveying unit 14 for double-sided image formation, and recording A fixing device 100 as a fixing unit for fixing a toner image on paper is provided. Reference numeral 16 denotes a registration roller that temporarily stops the conveyed recording paper and then conveys the recording paper toward the transfer unit 17 in synchronization with the formation of the toner image on the photoconductor 11.

The toner image formed on the photoreceptor 11 by charging, exposure and development is transferred to recording paper by a transfer means 17, and a toner image is formed on the recording paper.
0 is fixed.

The paper supply section 13a is operated by a paper supply start signal, and has paper supply means 131a for separating the recording paper stored in the cassette 132a one by one and starting to convey the recording paper. Similarly, the paper feeding units 13b and 13c
b and cassette 132b, sheet feeding means 131c and cassette 1
32c. The paper feeding unit 13d includes a large-capacity cassette 132d, and has paper feeding means 131d.

The document reading section 20 includes a document feed table 21 on which a document is placed, a platen roller 22 for conveying the document and forming a reading position, and a document discharge table 2 on which a read document is placed.
3. It has an image sensor 24 that receives image light and converts it into an image signal, and a platen glass 25 on which a document is placed.

The document feeding table 21 is provided with sensors S1 and S2 for detecting a document. These sensors S1, S2
Detects the size of the document and detects whether or not there is a document on the document feeder 21.

The original reading section 20 conveys the original from the original feeder table 21 and reads the original while conveying the original by the platen roller 22 or in a mode for reading the original placed on the platen glass 25. Do.

FIG. 5 is a front view of a fixing device 100 as a fixing unit. In the fixing device 100, an upper roller 101 which is a heating roller and a lower roller 1 which is a pressure roller and incorporates a heat source 103 such as a halogen lamp as a heating means.
02 are provided in pressure contact with each other. Upper roller 10
A roller 104 that applies the anti-offset agent supplied from the anti-offset agent supply device 105 to the upper roller 101 is in contact with the peripheral surface of the roller 1. The recording paper P on which the toner image has been formed enters between the upper roller 101 and the lower roller 102 rotating as shown by the arrow, as shown by the arrow P1, and the recording paper P is nipped by the upper roller 101 by the lower roller 102. In the course of transport, the toner image is heated and thermally fixed on the recording paper P.
The recording paper P on which the fixing has been completed is an elastic member S, and the upper roller 101
Separation claws 106A, 106B, 10
6C and the lower separation claw 10 which comes into contact with the lower roller 102 by its own weight.
The sheet is conveyed while being guided by 7A, 107B and 107C.

The elastic guide members 108A, 108B, 108C, 1 having one end fixed to the frame 109 of the fixing device 100 are provided.
08D are provided between the lower separation claws 107A, 107B and 107C and at four places on both ends (see FIG. 6). As shown in FIGS. 5 and 7A, the elastic guide members 108A, 108B, 108C and 108D are provided with lower separation claws 107A and 107A.
B and 107C have a top 1081 which is slightly higher than the projection 1071 provided on 107C. The top portion 1081 functions as a guide for guiding the recording paper P.

FIG. 6 is a side view of the fixing device 100.
As shown, the elastic guide members 108A, 108B, 108
C and 108D are recording papers P of the A3 size having the maximum length in the conveyance path width direction of the recording paper accommodated in the image forming apparatus or the horizontally long A4 size (the conveyance path width direction is a long side). When transported, the elastic guide members 108A, 108B, 1
08C and 108D are supported and guided from below over substantially the entire length thereof.

The elastic guide members 108A, 108B, 108
C and 108D, a conveyance path of the recording paper P is provided with a conveyance roller 110 and a roller 11 for reversing conveyance of the recording paper P.
A conveyor belt 113 is provided to be suspended between the conveyor belts 1 and 112. A transport switching lever 1 as a transport path switching unit
When the transport switching lever 114 is at the solid line position, the recording paper P is transported along a transport path that travels straight as indicated by an arrow P2 and is discharged outside the apparatus. When the transport switching lever 114 moves to the position indicated by the alternate long and short dash line, the recording paper P is guided by the transport switching lever 114 and guided to the downward transport path indicated by the arrow P3, and after being transported by the transport belt 113 and the transport roller 115, The sheet is conveyed downward by the reversing roller 118. As in FIG.
The reversing roller 118 performs reversal discharge or conveyance to the two-sided image forming conveyance path. As described above, the conveyance path of the recording paper after the fixing is switched by the conveyance switching lever 114.

Next, the recording paper P is moved to the lower separation claws 107A and 10A.
The guiding action of the convex portions 1071 of 7B and 107C and the guiding action of the elastic guide members 108A, 108B, 108C and 108D will be described with reference to FIG.

FIGS. 7A and 7B show the elastic guide member 10.
8A (108B, 108C, 108D) are shown separately when the transport path is switched as described above.

FIG. 7A shows a case where the recording paper P is discharged through a conveying path which moves straight as indicated by an arrow P2, and the recording paper P is discharged with the surface carrying the fixed toner image facing upward. Indicates the paper ejection mode to be performed. In this case, the elastic guide member 108A,
Top 10 which is the guide for 108B, 108C, 108D
Reference numeral 81 denotes a position slightly higher than the convex portion 1071 and the recording paper P
I will guide you.

FIG. 7B shows a case where the recording paper P is guided as shown by an arrow P3 and is conveyed to a reverse discharge or a double-sided image forming conveyance path. In this case, the recording paper P
Is bent downward by the transport switching lever 114 as shown by the arrow P3, and the elastic guide member 108
A acts on A, 108B, 108C, and 108D to press them downward. As a result, as shown in the figure, the elastic guide members 108A, 108B, 108C, and 108D are deformed by the elasticity according to the pressing force, the top portion 1081 is almost at the same height as the convex portion 1071, and the recording paper P is the elastic guide member 108A, It is guided and transported by the projections 1071 of the lower separation claws 107A, 107B, 107C.

In both cases shown in FIGS. 7A and 7B, the recording paper P is conveyed while maintaining a substantially linear shape in the width direction of the conveyance path as shown in FIG. Deflection is prevented. The discharged recording paper P was prevented from having the above-described wavy wrinkles that had conventionally occurred. In addition, the elastic guide members 108A, 108B, 108C, and 108D are elastically deformed when a bending force is applied during conveyance of the recording paper P, and the guide portions 1082 are displaced. Does not act, thereby preventing the recording paper from having irregularities.

The elastic guide members 108A, 108B, 108
8C, 108D, the guide member itself may be made of an elastic material such as a leaf spring, or as shown in FIG.
The portion forming 82 is formed of a rigid plate, rotatably mounted, and urged by an urging portion 1083 such as a coil spring or a flexible material such as a plastic film as shown in FIG. 8B. The guide section 1082 may be formed, and the guide section may be supported by an urging section 1083 made of an elastic material such as moltoprene.

[0037]

According to the first or second aspect of the present invention, it is possible to prevent the recording paper from having wavy wrinkles in the fixing device.

According to the third aspect of the present invention, wrinkling of recording paper is prevented in a widely used fixing device using two rollers and an upper roller as a heating roller.

According to the fourth or fifth aspect of the present invention, there is provided an image forming apparatus having a function of discharging a fixed recording sheet without reversing the front and back, a function of reversing the front and back and discharging, or a double-sided image forming function. In image formation in any mode, wrinkles can be prevented from occurring, and undesirable phenomena such as local unevenness other than the wrinkles can be prevented.

According to the sixth and seventh aspects of the present invention, the elastic guide member can be made of various materials.

[Brief description of the drawings]

FIG. 1 is a front view of a conventional fixing device.

FIG. 2 is a side view of the conventional fixing device shown in FIG.

FIG. 3 is a diagram illustrating the occurrence of wrinkles on a recording sheet.

FIG. 4 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention.

5 is a front view of a fixing device of the image forming apparatus shown in FIG.

6 is a side view of the fixing device shown in FIG.

FIG. 7 is an enlarged view of a recording paper guide section of the fixing device of FIG.

FIG. 8 is a view showing a modification of the elastic guide member.

[Explanation of symbols]

REFERENCE SIGNS LIST 100 fixing device 101 upper roller 102 lower roller 103 heat source 106A, 106B, 106C upper separating claw 107A, 107B, 107C lower separating claw 1071 convex portion 108A, 108B, 108C, 108D elastic guide member 109 frame 114 transport switching lever

Claims (7)

[Claims] 1. A fixing unit for heating a toner image while fixing the recording sheet while conveying the recording sheet while contacting the recording sheet carrying the toner image, and a plurality of positions in a conveying path width direction downstream of the fixing unit. And an elastic guide member for guiding the recording paper. 2. The image forming apparatus according to claim 1, wherein the fixing unit includes an upper roller and a lower roller for nipping and transporting the recording sheet, and a separating claw that contacts the upper roller and the lower roller to separate the recording sheet.
The image forming apparatus according to claim 1, wherein the separation claw that contacts the lower roller guides the recording paper together with the elastic guide member. 3. The image forming apparatus according to claim 1, wherein a heating unit is provided in the upper roller. 4. The image forming apparatus according to claim 1, further comprising a conveyance path switching unit that switches a recording paper conveyance path downstream of the elastic guide member. 5. When the recording sheet is conveyed by switching the conveyance path by the conveyance path switching means, the recording paper is conveyed in one conveyance path and when the recording paper is conveyed in the other conveyance path. The image forming apparatus according to claim 4, wherein a guide portion of the elastic guide member is displaced. 6. The apparatus according to claim 1, wherein said elastic guide member is made of a material having elasticity.
Item 10. The image forming apparatus according to item 1. 7. The elastic guide member according to claim 1, wherein the elastic guide member is constituted by a displaceable guide portion and an urging portion for urging the guide portion. An image forming apparatus according to claim 1.