JPS6385679A - Fixing device - Google Patents

Abstract

PURPOSE:To reduce the deformation of a recording form after it is discharged and to facilitate its separation by constituting a 1st separating claw member so that its pointed part which contacts a fixing roller and its guide part which guides an image support body are positioned on a straight line and this straight part is made nearly parallel to the line connecting the contact between the fixing roller and a pressure roller and the contact between a couple of upper and lower paper discharge rollers. CONSTITUTION:The pointed part 104a of the 1st separating claw member 104 constituted in contact with the fixing roller 101 and the guide part 104b which guides the recording form P successively to the pointed part 104a are positioned on the straight line. This straight line part 104c is installed nearly in parallel to the line C-C connecting the contact A between the fixing roller 101 and pressure roller 103 and the contact B between the couple of upper and lower paper discharge rollers. The front end of the recording form P after passing the contact A between the fixing roller 101 and pressure roller 102 is therefore separated from the surface of the fixing roller 101 by the front edge of the pointed part 104a speedily. Consequently, the deformation of the recording form after it is discharged is reduced and the paper has no wrinkles.

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 bag such as an electronic copying machine.

(Prior Art) In general, a fixing device in an image forming apparatus such as an electronic copying machine transports 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. 6, 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 is transported to an image support path Li. A recording paper P, which is a body, is guided between a fixing roller 101 and a pressure roller 102 via an entry guide 103, and after the toner image T is fixed on the recording paper P, the fixing roller 101 and the pressure roller 102 are guided. The recording paper P that has passed between is passed through a first peeling claw member 104 that contacts the fixing roller 101 and a second peeling claw member 105 that contacts the pressure roller 102, which constitute a peeling means. The paper is guided and conveyed between a pair of paper ejection rollers 106 and 107 and ejected, while a felt par 108 impregnated with a release agent as a cleaning means is pressed onto the fixing roller 101. There is.

The above-described peeling means, particularly the sharpened portion 104a of the first peeling claw member 104 that is brought into contact with the fixing roller 101, makes the tip of the peeling member 104 contact the surface of the fixing roller 101 to facilitate peeling off the recording paper P, and The angle is increased to prevent chipping, cracking, etc. of the sharp point made of a heat-resistant hard resin material, but with this shape,
If the sharpened portion 104a is close to the contact point 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 portion 104a, causing a paper jam. of.

Since it is necessary to contact the surface of the fixing roller 101 at a position away from the point of contact between the fixing roller 101 and the pressure roller 102, the tip of the sharpened portion 104a and the recording paper P after fixing are placed between a pair of upper and lower ejectors. Currently, the guide portion 104b that guides and conveys the paper toward the paper rollers 106 and 107 must be bent into a beak shape.

(Problems to be Solved by the Invention) However, if the sharpened portion 104a of the first peeling claw member 104 that is in contact with the fixing roller 101 is installed at a high position, the fixing roller 101 and the The leading edge of the recording paper P that has passed the contact point with the pressure roller 102 is largely curved upward along the fixing roller 101, and then peeled off from the surface of the fixing roller 101. The leading edge is pushed and warped in the opposite direction, and as a result, the ejected recording paper P becomes deformed into a large wavy state as shown in Figure 7. When the recording sheets P are bundled, they not only become bulky and have poor stackability, but also the deformed recording sheets P tend to wrinkle when being fixed twice in a double-sided copying machine or the like.

Also, the peeling claw member 1 brought into contact with the fixing roller 101
04 is made of heat-resistant hard resin material,
After long-term use, the fluororesin layer on the surface of the fixing roller 101 is significantly worn, and the sharp portion 104a
If the fixing roller 101 is used while the fixing roller 101 has chips or cracks, the fluororesin layer on the surface of the fixing roller 101 may be damaged, and as a result, the surface of the fixing roller 101 may partially peel off.

There have been problems such as toner adhering to the fixing roller 101 or poor fixing of the toner image, resulting in poor durability.

The present invention has been made under the above circumstances, and its purpose is to minimize the deformation of recording paper after it is ejected, and to reduce the wear of the fluororesin layer on the surface of the fixing roller. To provide a fixing device that can easily peel off recording paper without damaging it.

[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, a first peeling claw member in contact with the fixing roller, and a second peeling claw member in contact with the pressure roller. In the fixing device that peels off the image support after fixing and conveys it to a pair of upper and lower paper ejection rollers to eject the paper, the first peeling claw member has a sharpened portion that contacts the fixing roller; A guide portion that guides the image support is located in a straight line continuous with this sharp portion, and this straight portion is connected to a contact point between the fixing roller and the pressure roller and a contact point between the pair of upper and lower paper ejection rollers. It is a composition that is almost parallel to the lines connecting each.

(Function) In other words, the present invention has the above configuration,
The sharp part of the peeling claw member that contacts the fixing roller and the guide part that guides the image support are located on a straight line, and this straight part is connected to the contact point between the fixing roller and the pressure roller and the pair of upper and lower paper ejection rollers. Since the lines that connect the contact points are almost parallel to each other, the recording paper can be peeled off smoothly and guided and conveyed to the pair of upper and lower paper ejection rollers, thereby preventing deformation of the recording paper after ejecting the paper. This reduces the occurrence of paper wrinkles, and also allows the recording paper to be easily peeled off without abrading or damaging the fluororesin layer on the surface of the fixing roller. Since toner does not adhere or cause toner image fixation failure,
It becomes possible to improve durability.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings shown in FIGS. 1 to 5. In the illustrated embodiment of the present invention, parts having the same structure as those of the conventional fixing device shown in FIG. 6 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). In the figure, reference numeral 5 denotes an operation display section provided on the front edge of the upper surface of the copying machine main body 1, and includes a display 6, a numeric keypad 7, an exposure setting volume 8, a print key 9, and the like.

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
06.107, the toner image is transferred onto the copy paper P, and residual toner on the photoreceptor 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 processes the recording paper P, onto which toner 8L1' has been transferred in a developing section (not shown) and is conveyed onto a conveyance path, with a fixing roller 101. An entry guide 103 is placed between the pressure roller 102 and the pressure roller 102.
After the toner image T is fixed on the recording paper P, the recording paper P that has passed between the fixing roller 101 and the pressure roller 102 is moved to a first peeling point where the recording paper P comes into contact with the fixing roller 101. It has a structure in which the paper is guided and conveyed between a pair of upper and lower paper ejection rollers 106 and 107 via a claw member 104 and a second peeling claw member 105 that contacts the pressure roller 102, and is ejected. As shown in FIG. 4, the first peeling claw member 104 that is in contact with the fixing roller 101 has a sharpened portion 104a that is in contact with the fixing roller 101, and a sharpened portion 104a that is continuous with this sharpened portion 104a. The guide portion 104b that guides the recording paper P is positioned on a straight line, and the straight portion 104c is connected to a contact point A between the fixing roller 101 and the pressure roller 103 and a contact point B between the pair of upper and lower paper ejection rollers. They are installed so as to be substantially parallel to the line C-C connecting them.

That is, according to the configuration according to the present invention described above, the sharpened portion 104a of the first peeling claw member 104 that is brought into contact with the fixing roller 101, and the guide portion that guides the recording paper P continuously to the sharpened portion 104a. 104b on a straight line, and the straight part 104c is approximately parallel to the line C-C connecting the contact point A of the fixing roller 101 and the pressure roller 103 and the contact point B of the pair of upper and lower paper ejection rollers. Since the fixing roller 10 is installed so that
The recording paper P that has passed through the contact point A between 1 and the pressure roller 102
The leading edge of the recording paper P is quickly peeled off from the surface of the fixing roller 101 at the leading edge of the sharpened portion 104a, and as a result, the ejected recording paper P has large waves as in the conventional method, as shown in FIG. In addition, the sharp portion 104a of the first peeling claw member 104 can be made smaller than the deformed state (see FIG. 7).
An elastic body 110 made of heat-resistant rubber such as fluororubber coated with fluororesin or silicone rubber is attached to the tip contact surface that contacts the fixing roller 101,
By providing such a rubber layer at the tip of the sharpened portion 104a, the tip of the sharpened portion 104a can be brought into close contact with the fixing roller 101 by lightly touching it.
It does not damage the surface of the fixing roller 101, and by coating it with fluororesin, it can be prevented from abrasion and deterioration due to friction and heat with the fixing roller 101 and the recording paper P, and is comparable to conventional heat-resistant resins. This makes it possible to withstand long-term use. Furthermore, fluororesin
It has high lubricity and good adhesion to the fixing roller 101 due to the rubber, making it possible to improve the peelability of the recording paper P from the fixing roller 101.

In addition, in the above-described embodiment, the first peeling claw member 10
4, as long as the tip contact surface of the sharpened portion 104a that contacts the fixing roller 101 is an elastic body 110 made of heat-resistant rubber such as fluororubber coated with fluororesin or silicone rubber, other portions may be made of metal other than resin. .

In addition, it goes without saying that the present invention can be modified in various ways 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 sharpened portion of the peeling claw member that contacts the fixing roller and the guide portion that guides the image support are located on a straight line, and Since the straight portion is made almost parallel to the line connecting the contact point between the fixing roller and the pressure roller and the contact point between the upper and lower pair of paper ejection rollers, the recording paper is peeled off smoothly and is attached to the upper and lower pair of paper ejection rollers. Since the recording paper can be guided and conveyed by the recording paper, the deformation of the recording paper after discharge is reduced, and the occurrence of paper wrinkles can be reduced. In addition, since an elastic body is provided on the tip contact surface of the sharpened part of the peeling claw member, the recording paper can be easily peeled off without abrading or damaging the fluororesin layer on the surface of the fixing roller. This prevents toner from adhering to the fixing roller or causing poor fixing of toner images, making it possible to provide a fixing device that has an excellent effect of improving durability. It is possible.

[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. FIG. 6 is a schematic explanatory diagram of a conventional fixing device, and FIG. 7 is an explanatory diagram showing the deformed state of recording paper after ejecting the same conventional sheet. 100... Fixing device, 101... Fixing roller, 102... Pressure roller, 104... First peeling claw member. 104a... Sharp portion, 104b... Guide portion, 104c... Straight portion. 105... Second peeling claw member, 106.107... Paper discharge roller. A: Contact point between fixing roller and pressure roller, B: Contact point between paper ejection roller, T: Developer image (toner image), P: Image support (recording paper). Applicant's representative Patent attorney Takehiko Suzue Figures 3 and 4

Claims (3)

[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 bring it into contact with the fixing roller. A first peeling claw member brought into contact with the pressure roller and a second peeling claw member brought into contact with the pressure roller peel off the image support after fixing and transport the image support toward a pair of upper and lower paper ejection rollers to eject the paper. In the fixing device, the first peeling claw member has a sharpened portion that contacts the fixing roller and a guide portion that guides the image support in succession to the sharpened portion, and
A fixing device characterized in that the straight line portion is substantially parallel to a line connecting a contact point between the fixing roller and the pressure roller and a contact point between the pair of upper and lower paper ejection rollers. (2) The fixing device according to claim 1, wherein the contact surface of the sharpened portion that contacts the fixing roller is formed of an elastic material. (3) The fixing device according to claim 2, wherein the elastic body forming the contact surface of the sharp portion that contacts the fixing roller is made of heat-resistant rubber coated with fluororesin.