JPS6385680A - Fixing device - Google Patents

Abstract

PURPOSE:To reduce the deformation of a recording form after it is discharged as much as possible and to easily separate the recording form by positioning the pointed part of a separating claw member nearby the contact between a fixing roller and a pressure roller. CONSTITUTION:The front edge of the pointed part 104a of the separating claw member 104 which is brought into contact with the fixing roller 101 is made to come into contact at a position close to the contact A between the fixing roller 101 and pressure roller 103, and its guide part 104b is formed linearly along a couple of upper and lower paper discharge rollers 108 and 109. The front end of the recording form P after passing the contact A between the fixing roller 101 and pressure roller 102 is separated from the surface of the fixing roller 101 by the front edge of the pointed part 104a speedily. Consequently, the discharged recording form P is reduced in deformation as compared with such a conventional deformation state that the form waves large.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a fixing device installed in an image forming apparatus such as an electronic copying machine.

(Prior Art) Generally, a fixing device in an image forming apparatus such as an electronic copying machine conveys an image support onto which a developer image has been transferred between a fixing roller and a pressure roller, The image is fixed on the image support, and the fixed image support is peeled off via a peeling means and conveyed to the paper discharge roller side to be discharged.

Conventionally, as shown in FIG. 7, in this type of fixing device 100, a developer image (hereinafter referred to as a toner image) T is transferred in a developing section (not shown) and the image is transported onto a transport path. A recording paper P, which is a support, is guided between a fixing roller 101 and a pressure roller 102 via an entry guide 103, and after fixing the toner image T on the recording paper P, the fixing roller 101 and the pressure roller 102 is peeled off at the tip of the sharpened portion 104a of the peeling claw member 104 brought into contact with the circumference of the fixing roller 101.

The peeling claw member 104 is rotatably supported on a fixed portion of the apparatus main body via a support shaft 105, and the sharpened portion 104 is supported by a biasing force of a spring 106.
The tip of the fixing roller 4a is pressed into contact with the fixing roller 101 side.

Further, the recording paper P after fixing that has been peeled off by the peeling claw member 104 is guided and conveyed via a conveyance guide member 107 between a pair of upper and lower sheet discharge rollers 108 and 109 to be discharged. It has a structure in which a felt par 110 impregnated with a release agent as a cleaning means is pressed onto the above-described fixing roller 101.

The above-described peeling means, in particular, the sharp portion 104a of the peeling claw member 104 brought into contact with the fixing roller 101
The tip is brought into contact with the surface of the recording paper P to facilitate peeling off the recording paper P, and the angle is increased to prevent the occurrence of chips, cracks, etc. at the sharp point made of a heat-resistant hard resin material. However, with such a shape, the sharpened portion 104a
If the leading edge of the recording paper P is close to the contact point A between the fixing roller 101 and the pressure roller 102, the leading edge of the recording paper P will hit the leading edge of the sharpened part 104a, causing a paper jam. Since it is necessary to bring the tip into contact with the surface of the fixing roller 101 at a position away from the contact point A between the fixing roller 101 and the pressure roller 102, the sharpened portion 1
04a and a guide section 10 that guides and conveys the recording paper P after fixing to a pair of upper and lower paper ejection rollers 108 and 109.
The current situation is that 4b must be bent into a beak shape.

(Problems to be Solved by the Invention) However, with such a shape of the peeling claw member 104, there is a protrusion at the contact point between the fixing roller 101 and the pressure roller 102).
If A and the peeling point (contact point) B on the roller at the tip of the sharpened portion 104a are installed at a high position far apart, the recording paper P that has passed through the contact point between the fixing roller 101 and the pressure roller 102 The tip of the sheet is largely curved upward along the fixing roller 101, and then peeled off from the surface of the fixing roller 101.
Furthermore, the leading edge of the recording paper P is pushed at the first bent part and warped in the opposite direction, causing the ejected recording paper P to be deformed into a large wavy shape as shown in FIG. The recording paper P in this wavy state
It becomes bulky when tied together.

Not only will the stackability deteriorate, but also double-sided copying machines, etc.
When the recording paper P is fixed twice, there are problems in that the deformed recording paper P becomes wrinkled or is not peeled off sufficiently from the photoreceptor, resulting in jamming.

The present invention was made under the above circumstances.

The purpose is to provide a fixing device that minimizes the deformation of the recording paper after it is ejected and allows the recording paper to be easily peeled off.

[Structure of the Invention (Means for Solving the Problems)] In order to solve the above-mentioned problems, the present invention provides an arrangement in which an image support to which a developer image has been transferred is placed between a fixing roller and a pressure roller. to fix the image of the developer on the image support, and a peeling claw member rotatably supported on the circumference of at least one of the fixing roller and the pressure roller. In the fixing device, the image support after fixing is peeled off by bringing the tips of the sharp parts into contact with each other, and the image support after peeling is guided and conveyed to the paper ejection roller side by the guide section of the peeling claw member. The sharpened portion of the claw member is located close to the contact point between the fixing roller and the pressure roller.

(Function) That is, by having the above configuration, the present invention has the following features:
Since the sharp end of the peeling claw member is positioned close to the contact point between the fixing roller and the pressure roller, the recording paper can be peeled off smoothly, thereby preventing deformation of the recording paper after it is ejected. Since the paper can be made smaller, it is possible to reduce the occurrence of paper wrinkles, and it is also possible to reliably prevent jams at the photoreceptor portion during peeling.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings shown in FIGS. 1 to 6. In the illustrated embodiment of the present invention, parts having the same structure as those of the conventional fixing device shown in FIG. 7 will be described using the same reference numerals.

FIG. 1 shows the external appearance of an electronic copying machine which is an image forming apparatus equipped with a fixing device according to the present invention, and numeral 1 in the figure is the main body of the copying machine. On the right side of the copying machine main body 1,
A paper feed cassette 2 capable of automatic or manual paper feeding is installed, and a paper output tray 3 is installed on its left side. A document table 4 is provided that can freely reciprocate in the direction (direction of arrow a). Reference numeral 5 in FIG. 1 denotes an operation display section provided on the front edge of the upper surface of the copying machine main body 1, and a display 6. It consists of a numeric keypad 7, an exposure setting volume 8, a print key 9, etc.

Next, the internal mechanism of the copying machine main body 1 will be explained with reference to FIG.

In the figure, reference numeral 10 denotes a drum-shaped photoreceptor as an image carrier that is rotatably supported approximately in the center of the copying machine main body 1, and is synchronized with the document table 4 by a drive mechanism (not shown). It is designed so that it can be rotated in both directions. This photoreceptor 10 is uniformly charged by a charger 11,
The document image irradiated by the exposure lamp 12 is imaged onto the photoreceptor 10 by a focusing light transmission body (trade name: SELFOC lens array) 13 constituting an optical system device to form an electrostatic latent image. The photoreceptor 1, which will be described later, is attached to this electrostatic latent image.
Toner is supplied and developed by a developing device 14 disposed around and in opposition to the periphery of the toner image T, and this toner image T is sent to the transfer charger 15 side.

The transfer charger 15 transfers a toner image onto copy paper P made of plain paper as an image support, which is fed from a paper feed cassette 2 that is automatically or manually fed via a paper feed roller 16 and a pair of registration rollers 17 and 17. After the transfer, the copy paper P is peeled off from the photoreceptor 10 by a peeling charger 18 using AC corona discharge, and passed through a conveying path 19, where the toner image T is melted and fixed by a fixing device 100, which will be described later. , a pair of upper and lower paper ejection rollers 1
08.109, the toner image is transferred onto the copy paper P, and residual toner on the photoconductor 10 after peeling off is cleaned by the cleaning device 21 and static electricity is removed. The lamp 22 lowers the potential on the photoreceptor 10 below a certain level to enable the next copying operation.

As shown in detail in FIG. 3, the above-mentioned fixing device 100 transfers the recording paper P onto which the toner image T has been transferred by a developing section (not shown) and is transported onto the transport path to the fixing roller 1.
01 and the pressure roller 102, and after fixing the toner image T on the recording paper P, the recording paper P passed between the fixing roller 101 and the pressure roller 102. is peeled off by the peeling claw member 104 in contact with the fixing roller 101, and the conveyance guide member 10
5, the paper is guided and conveyed between a pair of upper and lower paper ejection rollers 108 and 109, and the paper is ejected. As shown in FIG. 2, it consists of a sharpened portion 104a that is brought into contact with the fixing roller 101, and a guide portion 104b that guides the recording paper P continuously from this sharpened portion 104a, and the top surface 204 of the leading edge of this sharpened portion 104a is The closest position I+'! within 10 mm from the contact point A with the pressure roller 102 on the circumference of the fixing roller 101! B, and the top surface 204 of the tip is shaped so that the angle θ between the peeling point B on the roller and the tangent C-C of this peeling point B is an acute angle. On the other hand, the lower surface side which becomes the guide portion 104b is formed linearly from the peeling point B toward the side of the paper discharge rollers 108 and 109, and its cross-sectional shape is shown in FIG. The ridge line 205 is formed along the transport direction on at least the surface of the lower surface of the guide portion 104b that contacts the recording paper P, thereby reducing the contact with the recording paper P. This is designed to reduce the occurrence of jamming of the recording paper P due to dirt on the peeling claw member 104.

That is, according to the configuration according to the present invention described above.

The tip of the sharp part 104a of the peeling claw member 104 that has been brought into contact with the fixing roller 101 is connected to the fixing roller 101 and the pressure roller 1.
03 at a position close to the contact point A, and the guide portion 104b is connected to a pair of upper and lower paper ejection rollers 108 and 109.
Since it is formed linearly along the side, the leading edge of the recording paper P that has passed through the contact point A between the fixing roller 101 and the pressure roller 102 is quickly separated from the surface of the fixing roller 101 at the tip of the sharpened portion 104a. As a result, the ejected recording paper P can be made smaller than the conventional large wavy deformed state (see Fig. 8), as shown in Fig. 6. It is something that

By the way, the occurrence rate of wrinkles on the recording paper P and Regarding the jam rate at the photoreceptor part, at a distance of 15 mm, the wrinkle occurrence rate is 100% and the jam rate is 3.
However, at a close distance of 8 mm, the wrinkle occurrence rate was 30% and the jam rate was 0%, and at a close distance of 5 mm, both the wrinkle occurrence rate and the jam rate were 0%. there were.

It should be noted that the present invention is not limited to the above-described embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

[Effects of the Invention] As is clear from the above description, according to the present invention, the image support to which the developer image has been transferred is conveyed between the fixing roller and the pressure roller, and the developer image is transferred between the fixing roller and the pressure roller. While fixing the image on the image support, the image is fixed by contacting the tip of the pointed part of a peeling claw member that is pivotably supported for nine rotations on the circumference of at least one of the fixing roller and the pressure roller. In a fixing device that peels off the subsequent image support and guides and conveys the peeled image support toward the paper ejection roller using the guide portion of the peeling claw member, the sharp end of the peeling claw member is connected to the fixing roller. Because it is located close to the point of contact with the pressure roller, the recording paper can be peeled off smoothly, and this reduces the deformation of the recording paper after it is ejected, thereby reducing the occurrence of paper wrinkles. Therefore, it is possible to provide a fixing device that has excellent effects in that it is possible to reduce the number of particles and to reliably prevent jamming at the time of peeling on the photoreceptor portion.

[Brief explanation of the drawing]

FIG. 1 is an external perspective view showing an embodiment in which an electronic copying machine as an image forming apparatus is equipped with a fixing device according to the present invention;
3 is a schematic explanatory diagram showing the internal structure, FIG. 3 is a schematic explanatory diagram of the fixing device, FIG. 4 is a schematic explanatory diagram of the peeling claw member that contacts the fixing roller, and FIG. ■−■
6 is an explanatory diagram showing the deformed state of the recording paper after being ejected, FIG. 7 is a schematic explanatory diagram of the conventional fixing device, and FIG. 8 is the same FIG. 3 is an explanatory diagram showing a deformed state of recording paper after being ejected. 100...Fixing device. 101... Fixing roller, 102... Pressure roller, 104... Peeling claw member, 104a... Sharp portion, 104b... Guide portion, 108.109... Paper discharge roller. A...Contact point between fixing roller and pressure roller, B...Peeling point (roller contact point), T...Developer image (toner image), P...Image support (recording paper) ). Figures 5 and 6

Claims (4)

[Claims] (1) The image support to which the developer image has been transferred is conveyed between a fixing roller and a pressure roller to fix the developer image onto the image support, and the fixing roller and pressure roller The fixed image support is peeled off by contacting the tip of the sharp end of a rotatably supported peeling claw member with the circumference of at least one of the rollers, and the guide portion of the peeling claw member In the fixing device configured to guide and convey the image support after peeling off toward the paper ejection roller side, the sharpened part of the peeling claw member is located close to the contact point between the fixing roller and the pressure roller. Fusing device. (2) The fixing device according to claim 1, wherein the tip of the sharpened portion of the peeling claw member is located within 10 mm from the contact point between the fixing roller and the pressure roller. (3) The guide portion of the image support of the peeling claw member is formed linearly from the peeling point toward the paper ejection roller side. The fixing device described in . (4) The sharpened part of the peeling claw member is shaped so that the peeling point on the roller at the tip thereof and the tangent to the peeling point form an acute angle. A fixing device according to any one of claims 1 to 3.