JP2017015934A - Fixation device and image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the behavior of a recording material at the time when a recording material reaches a fixation part.SOLUTION: A guide surface 55 for guiding a sheet conveyed from the lower side is provided on one surface (surface on the lower side) of a first guide member 48. A downstream side guide part 473 for further guiding the sheet is provided on the downstream side with respect to (the guide surface 55 of) the first guide member 48 in the conveyance direction of the sheet. The downstream side guide part 473 is arranged in the state where there is a step 56 between the guide surface 55 provided in the first guide member 48 and itself. The step 56 is provided with the guide member 70. The guide member 70 guides the sheet conveyed through the first guide member 48 to the downstream side guide part 473 located on the downstream side and a fixation part N. The guide member 70 fills in the step 56 and reduces the difference of elevation between the guide surface 55 and downstream side guide part 473.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a fixing device and an image forming apparatus.

Patent Document 1 discloses a fixing device including a fixing nip and an introduction guide member for introducing a sheet-shaped transfer material into the fixing nip.
In Patent Document 2, a fixing device is disposed substantially vertically above a secondary transfer roller for transferring an unfixed toner image on an intermediate transfer member onto a transfer sheet, and a guide member made of a resin sheet is provided therebetween. An image forming apparatus is disclosed.
Further, Patent Document 3 discloses a fixing device including a heating roller and a pressure roller that face each other in a pressure contact state, and an inlet guide for guiding a sheet between the heating roller and the pressure roller. Yes.

JP 2011-22243 A JP 2008-96900 A JP 2001-5316 A

In an image forming apparatus or the like, a recording material on which an image is formed may be heated or pressed to fix the image on the recording material. Here, if there is a step in front of the fixing unit, the behavior of the recording material becomes unstable, and there is a possibility that the quality of the fixed image is deteriorated.
An object of the present invention is to stabilize the behavior of the recording material when the recording material reaches the fixing portion.

According to the first aspect of the present invention, there is a step between the guide surface that guides the recording material on which an image is placed and the guide surface in the recording material transport direction, and between the guide surface. A downstream guide portion that guides the recording material, a fixing portion that fixes the image onto the recording material guided by the downstream guide portion, and the guide surface and the downstream guide portion. And a guide member that is disposed at the level difference and guides the recording material to the downstream side.
According to a second aspect of the present invention, the guide member is disposed with a gap between the guide member and the downstream guide portion, and is elastically deformed by being pressed by the conveyed recording material. The fixing device according to claim 1, wherein the fixing device is in contact with the fixing device.
According to a third aspect of the present invention, the guide member is formed so as to advance from the side on which the guide surface is provided toward the downstream guide portion, and a downstream end portion in the advancing direction is provided. The fixing device according to claim 1, wherein the fixing device has a free end and is provided in a cantilever shape.
According to a fourth aspect of the present invention, a gap is formed between the guide surface and the downstream guide portion in the conveyance direction of the recording material, and the guide member extends from the guide surface side to the downstream guide portion. The fixing device according to claim 1, wherein the fixing device is provided so as to cross the gap.
According to a fifth aspect of the present invention, when the recording material is moving toward the fixing unit, the leading edge of the recording material is in the width direction of the recording material, which is a direction intersecting the moving direction of the recording material. The part of the leading end of the recording material in the width direction is moved in a state where the part of the leading end of the recording material precedes the other part in the width direction. The fixing device according to claim 1, further comprising a lowering unit that lowers the moving speed.
According to a sixth aspect of the present invention, there is provided an image forming means for forming an image on a recording material, a guide surface for guiding the recording material on which an image is formed by the image forming means, and a guide surface in the recording material transport direction than the guide surface. A downstream guide unit that is arranged on the downstream side and has a step between the guide surface and guides the recording material, and an image on the recording material guided by the downstream guide unit. An image forming apparatus comprising: a fixing unit that performs fixing; and a guide member that is disposed at the step between the guide surface and the downstream guide unit and guides a recording material downstream.

According to the first aspect of the present invention, the behavior of the recording material when the recording material reaches the fixing portion can be stabilized as compared with the case where the guide member is not provided.
According to the second aspect of the invention, it is possible to stabilize the behavior of the recording material when the recording material reaches the fixing portion while extending the life of the guide member.
According to the third aspect of the present invention, the recording material can be supplied more smoothly to the fixing unit than when both the downstream end and the upstream end of the guide member are supported.
According to the fourth aspect of the present invention, it is possible to prevent the recording material from going to a place other than the fixing portion through the gap.
According to the invention of claim 5, the inclination of the recording material can be corrected.
According to the sixth aspect of the present invention, the behavior of the recording material when the recording material reaches the fixing portion can be stabilized as compared with the case where no guide member is provided.

1 is an overall configuration diagram of an image forming apparatus according to an embodiment. FIG. 4 is a diagram illustrating a secondary transfer unit and a fixing device. FIG. 6 is a diagram for explaining the behavior of a sheet from a secondary transfer unit to a fixing device. It is the perspective view which showed the fixing device and the 1st guide member. (A) and (B) are diagrams showing the behavior of the paper in the fixing device. It is the figure which showed the other structural example of the downstream guide part, the guide member, and the 1st guide member. FIG. 10 is a diagram illustrating another configuration example of the first guide member and the fixing device.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is an overall configuration diagram of an image forming apparatus 1 according to the present embodiment.
The image forming apparatus 1 is a so-called tandem color printer. The image forming apparatus 1 includes an image forming process unit 10 as an example of an image forming unit that forms an image on a sheet that is an example of a recording material. The image forming process unit 10 forms an image on a sheet based on the image data of each color.

The image forming apparatus 1 is provided with a control unit 30 that controls the overall operation of the image forming apparatus 1. Further, the image forming apparatus 1 is provided with an image processing unit 35.
The image processing unit 35 performs image processing on image data transmitted from the personal computer (PC) 3, the image reading device 4, or the like. Further, the image forming apparatus 1 is provided with a main power source 36 that supplies power to each unit.

The image forming process unit 10 is provided with four image forming units 11Y, 11M, 11C, and 11K (hereinafter collectively referred to as “image forming unit 11”) that are arranged in parallel at regular intervals. It has been.
Each image forming unit 11 has the same configuration except for toner stored in a developing device 15 (described later). Each image forming unit 11 forms yellow (Y), magenta (M), cyan (C), and black (K) toner images.

Each of the image forming units 11 is provided with a photosensitive drum 12, a charger 200 that charges the photosensitive drum 12, and an LED print head (LPH) 300 that exposes the photosensitive drum 12.
The photosensitive drum 12 is charged by the charger 200. Further, the photosensitive drum 12 is exposed by the LPH 300, and an electrostatic latent image is formed on the photosensitive drum 12.
Further, each image forming unit 11 is provided with a cleaner (not shown) for cleaning the surface of the photosensitive drum 12 and a developing device 15 for developing the electrostatic latent image formed on the photosensitive drum 12.

  Further, the image forming process unit 10 includes an intermediate transfer belt 20 onto which the color toner images formed on the photosensitive drum 12 are transferred, and the color toner images formed on the photosensitive drum 12 to the intermediate transfer belt 20. A primary transfer roll 21 for sequential transfer (primary transfer), a secondary transfer roll 22 for batch transfer (secondary transfer) of the toner image transferred on the intermediate transfer belt 20 to the paper, and a secondary transferred image on the paper A fixing device 45 for fixing is provided.

  In the image forming apparatus 1, image data from the PC 3 and the image reading device 4 is subjected to image processing by the image processing unit 35 and supplied to each image forming unit 11 via an interface (not shown). For example, in the black (K) color image forming unit 11K, the photosensitive drum 12 is charged by the charger 200 while rotating in the direction of arrow A, and light is emitted based on the image data transmitted from the image processing unit 35. The exposure is performed by the LPH 300.

As a result, an electrostatic latent image related to a black (K) color image is formed on the photosensitive drum 12.
The electrostatic latent image formed on the photosensitive drum 12 is developed by the developing device 15, and a black (K) toner image is formed on the photosensitive drum 12.
Similarly, yellow (Y), magenta (M), and cyan (C) color toner images are formed in the image forming units 11Y, 11M, and 11C, respectively.

The color toner images formed by the image forming units 11 are sequentially electrostatically attracted by the primary transfer roll 21 on the intermediate transfer belt 20 that moves in the direction of arrow B to form a toner image on which the color toners are superimposed. The
The toner image on the intermediate transfer belt 20 is conveyed to a region (secondary transfer portion T) where the secondary transfer roll 22 is disposed as the intermediate transfer belt 20 moves.

When the toner image is conveyed to the secondary transfer unit T, the paper is supplied from the sheet holding unit 40 to the secondary transfer unit T in accordance with the timing at which the toner image is conveyed to the secondary transfer unit T.
Then, the toner image on the intermediate transfer belt 20 is electrostatically transferred collectively to the conveyed paper by the transfer electric field formed by the secondary transfer roll 22 in the secondary transfer portion T.

Thereafter, the sheet on which the toner image is electrostatically transferred is peeled off from the intermediate transfer belt 20 and conveyed to the fixing device 45. The toner image on the paper conveyed to the fixing device 45 is fixed on the paper by the fixing device 45 being subjected to a fixing process by heat and pressure.
Then, the sheet after the fixing is completed is conveyed to the sheet stacking unit 41 by the discharge roll 500.

FIG. 2 is a diagram illustrating the secondary transfer unit T and the fixing device 45.
The fixing device 45 includes a fixing roll 46 in which a heater H as a heating source is disposed, and a pressure module 47 pressed against the fixing roll 46.
A fixing portion (nip portion) N is provided at a contact portion between the fixing roll 46 and the pressure module 47. In the fixing unit N, the paper is pressurized and heated to fix the toner image on the paper to the paper.

  The fixing roll 46 is made of, for example, aluminum and is formed in a cylindrical shape. Further, the fixing roll 46 receives a rotational driving force from a motor (not shown) and rotates in a direction indicated by an arrow 2A in the drawing.

The pressure module 47 is provided with an endless belt member 471. The belt member 471 is disposed in contact with the outer peripheral surface of the fixing roll 46, receives the driving force from the fixing roll 46, and rotates in the direction indicated by the arrow 2B.
The pressing module 47 is provided with a pressing pad 472 that is disposed inside the belt member 471 and presses the fixing roll 46 via the belt member 471.

In the fixing device 45 of the present embodiment, the pressure module 47 is not located directly above the fixing roll 46 (upward in the vertical direction), and the pressure module 47 is disposed diagonally right above the fixing roll 46. ing.
For this reason, in this embodiment, the sheet is supplied from the lower right side in the drawing to the fixing device 45, and the sheet is discharged to the upper left side in the drawing.

The secondary transfer portion T will be described.
As described above, the secondary transfer portion T is provided with the secondary transfer roll 22 that collectively transfers the toner images on the intermediate transfer belt 20 onto the sheet. Further, at the secondary transfer portion T, a backup roll 25 is disposed inside the intermediate transfer belt 20.
In the present embodiment, the secondary transfer roll 22 is pressed against the backup roll 25 via the intermediate transfer belt 20.

In the secondary transfer portion T, the secondary transfer roll 22 is provided obliquely below and to the right of the backup roll 25. For this reason, the sheet that has passed through the secondary transfer portion T is conveyed in the upper right direction in the drawing.
In this embodiment, as described above, the sheet is supplied to the fixing device 45 from the lower right side of the fixing device 45 to the fixing device 45. On the other hand, the sheet that has passed the secondary transfer portion T moves in the upper right direction in the figure. In this case, the moving direction of the sheet upward from the secondary transfer portion T and the entering direction of the sheet when the sheet enters the fixing device 45 are inconsistent, and it becomes difficult to supply the sheet to the fixing device 45.

Therefore, in the present embodiment, a first guide member 48 for guiding the sheet to the fixing device 45 is provided on the moving path along which the sheet moving upward from the secondary transfer portion T moves, and this first guide member is provided. 48 is used to guide the sheet to the fixing device 45.
In the present embodiment, a second guide member 49 for guiding the sheet to the first guide member 48 is provided below the first guide member 48 in the drawing (on the side closer to the secondary transfer portion T). ing.

In the present embodiment, when a sheet having low rigidity such as a thin sheet is conveyed, the sheet is guided by the second guide member 49 and the first guide member 48 and moves toward the fixing device 45.
Further, when a highly rigid sheet such as a thick sheet is conveyed, the sheet is linearly directed to the first guide member 48, and then guided by the first guide member 48 to the fixing device 45.

FIG. 3 is a diagram for explaining the behavior of the sheet from the secondary transfer portion T toward the fixing device 45.
The sheet that has passed through the secondary transfer portion T is directed to the fixing device 45, and at this time, the sheet is guided by the first guide member 48.
Specifically, when the sheet is a thin sheet or the like, the sheet is guided by the first guide member 48 after being guided by the second guide member 49. Further, when the paper is a thick paper, the paper is guided by the first guide member 48 without being guided by the second guide member 49.

When the sheet is guided by the first guide member 48, first, as indicated by reference numeral 3 </ b> A, the leading end of the sheet comes into contact with the first guide member 48.
Thereafter, in the present embodiment, the tip slides on the first guide member 48 toward the fixing device 45 as indicated by an arrow 3B in the drawing. Finally, this leading edge enters the fixing portion N of the fixing device 45.

FIG. 4 is a perspective view showing the fixing device 45 and the first guide member 48.
The first guide member 48 is formed in a plate shape. A guide surface 55 is provided on one surface (the lower surface in the drawing) of the first guide member 48 for guiding the sheet conveyed from below. Further, a downstream guide portion 473 for further guiding the sheet is provided on the downstream side of the first guide member 48 (the guide surface 55) in the sheet conveyance direction.

  In the present embodiment, the downstream guide unit 473 guides the sheet, and then the sheet goes to the fixing unit N. Here, the downstream guide portion 473 is configured by an outer peripheral surface of a belt member 471 provided in the pressurizing module 47.

The downstream guide portion 473 is arranged with a step 56 between the downstream guide portion 473 and the guide surface 55 provided on the first guide member 48.
More specifically, in the present embodiment, the downstream guide portion 473 is not located on the extension line 48B of the guide surface 55, but is located above the extension line 48B in the drawing, and the extension line 48B. And the downstream guide portion 473 has a step 56.

More specifically, in the present embodiment, as a result of the sheet being fed from below, the sheet is urged upward in the figure (the direction indicated by arrow 4A in the figure). In the direction in which this urging is performed, The downstream side guide part 473 is located downstream from the extension line 48B.
In other words, in the paper urging direction, the extension line 48B is positioned on the upstream side, and the downstream guide portion 473 is positioned on the downstream side.

Furthermore, in this embodiment, a guide member (mylar) 70 is provided at the step 56.
The guide member 70 is made of a resin material such as PET, and is formed in a plate shape. The guide member 70 guides the sheet conveyed through the first guide member 48 to the downstream guide unit 473 and the fixing unit N located on the downstream side. Further, the guide member 70 fills the step 56 and reduces the height difference between the guide surface 55 and the downstream guide portion 473.

  The guide member 70 is formed so as to advance toward the downstream guide portion 473 from the side where the first guide member 48 is provided, and the downstream end portion 70A in the advancing direction is a free end. And cantilevered.

More specifically, the guide member 70 is fixed to the back surface 48C (the surface opposite to the guide surface 55) of the first guide member 48, and the downstream side guide portion 473 starts from the position fixed to the back surface 48C. It is installed to extend toward.
Further, the guide member 70 is installed in contact with the outer peripheral surface of the belt member 471.

In this embodiment, the leading edge of the sheet slides on the guide surface 55 and the leading edge reaches the downstream guide portion 473. In the present embodiment, the leading edge of the sheet is interposed between the guide surface 55 and the downstream guide portion 473. When there is a step 56 and the leading edge of the paper reaches this step 56, the leading edge of the paper is likely to jump.
In this case, the toner image (unfixed toner image) on the paper may be disturbed. Therefore, in the present embodiment, the guide member 70 is installed at the step 56 so as to suppress the tip bounce.

Further, the guide member 70 has a function of preventing the sheet from going to other than the fixing unit N.
In the present embodiment, as shown in FIG. 4, the installation position of the guide surface 55 and the installation position of the downstream guide portion 473 are shifted in the sheet conveyance direction, and the guide surface 55 and the downstream guide portion 473 are not aligned. A gap GP1 is formed between them. If the gap GP1 is formed in this way, the sheet may pass through the gap GP1 to other than the fixing portion N.

On the other hand, in this embodiment, the guide member 70 is provided from the guide surface 55 side to the downstream guide portion 473 side, and the guide member 70 crosses the gap GP1.
As a result, the sheet is prevented from entering the gap GP1, and the sheet is suppressed from going to a place other than the fixing portion N through the gap GP1.

4 indicates the leading edge PF of the sheet being guided by the guide surface 55.
When the sheet is moving toward the fixing unit N, the leading end PF of the sheet extends in the width direction of the sheet, which is a direction that intersects the moving direction of the sheet.
Here, the sheet may be inclined during the conveyance of the sheet, and the leading edge PF of the sheet is also inclined accordingly. More specifically, as shown in FIG. 4, the leading edge PF is inclined so that a part PF1 in the width direction of the sheet precedes another part PF2 in the width direction.

In the present embodiment, there is provided a lowering portion 80 for reducing the moving speed of the preceding partial PF1 (hereinafter referred to as “preceding portion PF1”), and the lowering portion 80 is used to move the preceding portion PF1. Reduce speed.
As a result, another portion PF2 (hereinafter referred to as “delayed portion PF2”) catches up with the preceding portion PF1, and accordingly, the inclination of the sheet is reduced.

  Here, in the present embodiment, the guide surface 55 includes a first guide surface 551 located on the downstream side and a second guide surface 552 located on the upstream side, and further, the first guide surface 551 and the second guide surface 552. The first guide surface 551 and the second guide surface 552 are crossed so that the angle formed with the guide surface 552 becomes an obtuse angle.

  The preceding portion PF1 exceeds the connecting portion 553 (the location where the first guide surface 551 and the second guide surface 552 intersect) between the first guide surface 551 and the second guide surface 552, and reaches the first guide surface 551. Then, the leading portion PF1 is caught on the first guide surface 551.

  More specifically, the leading portion PF1 moves to the connecting portion 553 while sliding on the second guiding surface 552, and then reaches the first guiding surface 551. When reaching the first guiding surface 551, the leading portion PF1 is A larger drag force is received from the first guide surface 551 than when the second guide surface 552 is slid.

In addition, the first guide surface 551 is not located on the extension line of the second guide surface 552 and has an inclination with respect to the extension line of the second guide surface 552, so that the preceding portion PF1 is the first portion PF1. When reaching the guide surface 551, the preceding portion PF1 receives a drag force from the first guide surface 551.
On the other hand, the delay portion PF2 is sliding on the second guide surface 552 at this time, and the drag acting on the delay portion PF2 is smaller than the drag acting on the preceding portion PF1.
As a result, the delayed portion PF2 approaches the preceding portion PF1, and the inclination of the leading edge PF of the sheet is reduced.

Furthermore, in the configuration of the present embodiment, image disturbance due to the unfixed toner image on the paper touching the fixing roll 46 is suppressed.
5A and 5B are diagrams illustrating the behavior of the sheet in the fixing device 45. FIG.
In the present embodiment, as shown in FIG. 5A, when the leading edge PF of the sheet that has been moved while being guided by the second guiding surface 552 reaches the first guiding surface 551, the leading edge PF is caused by the first guiding surface 551. Is pushed (the tip PF is pushed back to the upstream side in the paper urging direction), and the paper is curved so as to protrude in the direction away from the fixing roll 46.
As a result, the surface of the paper on which the toner image is formed (image forming surface) is separated from the fixing roll 46, and image disturbance due to the toner image touching the fixing roll 46 is less likely to occur.

On the other hand, as shown in FIG. 5B, when the guide surface 55 is formed in a straight line, the above-mentioned curve that protrudes in the direction away from the fixing roll 46 hardly occurs, and FIG. The toner image on the paper comes closer to the fixing roll 46 than in the case indicated by.
In this case, compared with the case shown in FIG. 5A, the toner image is easy to touch the fixing roll 46, and the toner image is likely to be disturbed.

FIG. 6 is a view showing another configuration example of the downstream guide portion 473, the guide member 70, and the first guide member 48.
In this configuration example, a gap GP2 is formed between the guide member 70 and the downstream side guide portion 473 (the outer peripheral surface of the belt member 471), and when the sheet is not conveyed, the guide member 70 is moved from the downstream side guide portion 473. It is separated. Thereby, compared with the case where the downstream guide part 473 and the guide member 70 are always contacting, abrasion of the guide member 70 and the belt member 471 is suppressed.

When the sheet is conveyed to the guide member 70, the guide member 70 is pressed and elastically deformed by the sheet and comes into contact with the downstream side guide portion 473 as indicated by a broken line 6A.
Then, the sheet reaches the downstream guide portion 473 while sliding on the guide member 70. At this time, the surface of the guide member 70 has a curvature so as to gradually approach the downstream guide portion 473, and thereby the sheet smoothly moves to the downstream guide portion 473.
When the sheet passes through the guide member 70, the guide member 70 returns to the original state and is separated from the downstream side guide portion 473.

(Other configurations)
FIG. 7 is a diagram illustrating another configuration example of the first guide member 48 and the fixing device 45.
In this configuration example, a gap GP3 is formed between the first guide member 48 and the downstream guide portion 473. Further, in this configuration example, a regulating member 90 that regulates the movement of the paper is provided.

The restricting member 90 is attached to a position located on the opposite side of the second guide surface 552 on the back surface of the first guide member 48.
Further, the regulating member 90 is provided so as to go to the outer peripheral surface of the pressurizing module 47, starting from a place attached to the first guide member 48. More specifically, the pressure module 47 is provided so as to face a portion 474 located on the upstream side of the downstream guide portion 473 (a portion located on the upstream side in the moving direction of the belt member 471).

  In this configuration example, even if the paper passes through the gap GP3, the paper hits the regulating member 90 and the movement of the paper is restricted. As a result, it is possible to prevent paper jamming at places where it is difficult to remove the paper, such as the back side of the apparatus.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 10 ... Image formation process part, 45 ... Fixing apparatus, 55 ... Guide surface, 56 ... Level difference, 70 ... Guide member, 70A ... End part, 80 ... Decrease part, 473 ... Downstream side guide part, GP1 ... Gap, GP2 ... Gap, N ... Fixing part

Claims (6)

A guide surface for guiding the recording material on which the image is placed;
A downstream guide portion that is disposed downstream of the guide surface in the recording material conveyance direction and that has a step between the guide surface and guides the recording material;
A fixing unit that fixes the image on the recording material guided by the downstream guide unit;
A guide member that is disposed at the step between the guide surface and the downstream guide portion and guides the recording material to the downstream side;
A fixing device.   The guide member is disposed with a gap between the guide member and the downstream guide unit, and is elastically deformed by being pressed by the conveyed recording material, and contacts the downstream guide unit. Item 4. The fixing device according to Item 1.   The guide member is formed so as to advance from the side on which the guide surface is provided toward the downstream guide portion, and a downstream end portion in the advancing direction is a free end, and is cantilevered. The fixing device according to claim 1, wherein the fixing device is provided in a beam shape. In the recording material conveyance direction, a gap is formed between the guide surface and the downstream guide portion,
The fixing device according to claim 1, wherein the guide member is provided from the guide surface side to the downstream guide portion side and is provided so as to cross the gap. When the recording material is moving toward the fixing unit, the leading edge of the recording material extends in the width direction of the recording material, which is a direction intersecting the moving direction of the recording material,
When the recording material is moved in a state where a part of the leading end of the recording material in the width direction precedes another part in the width direction, the moving speed of the preceding part is reduced. The fixing device according to claim 1, further comprising a lowering unit that causes the reduction. Image forming means for forming an image on a recording material;
A guide surface for guiding the recording material on which an image is formed by the image forming means;
A downstream guide portion that is disposed downstream of the guide surface in the recording material conveyance direction and that has a step between the guide surface and guides the recording material;
A fixing unit that fixes the image on the recording material guided by the downstream guide unit;
A guide member that is disposed at the step between the guide surface and the downstream guide portion and guides the recording material to the downstream side;
An image forming apparatus comprising:

Images