JPS6023869A - Fixing device - Google Patents

Abstract

PURPOSE:To stabilize image quality over a long period of time by covering the entire surface of a fixing roll and a pressing roll with covers and preventing sticking of a suspended toner thereto. CONSTITUTION:A passage opening which allows passage of copying paper 14 therethrough is provided to a fixing roll 5 and a pressing roll 6 and covers 7, 8 which cover the entire surface of said rolls are provided to said rolls respectively from above and below in the longitudinal direction thereof. The bottom end side of the front surface 15 and rear surface 16 of the cover 7 and the top end side of the front surface 17 and rear surface 18 of the cover 8 are respectively bent inward and the tips thereof are held in proximity to the surfaces of the rolls 5, 6. Through-holes 22, 23 are respectively provided to both right and left side surfaces 20, 21 of the covers 7, 8 so that the revolving shafts 24, 25 of the roll 5 and the roll 6 pass therethrough. The toner suspended in the machine body is prevented from sticking to the fixing roll and the pressing roll by such constitution and the image quality is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fixing device for use in equipment that utilizes an electrophotographic process, such as electrophotographic copying machines, facsimile machines, and printers.

[Prior art]

In conventional copying machines that use electrophotographic processes,
It is necessary to fix an unfixed toner image formed on copy paper to make a permanent image, and known fixing methods include a solvent fixing method, a pressure fixing method, and a heat fixing method.

The above-mentioned solvent fixing method uses a vapor or liquid solvent to dissolve the toner and infiltrate it into the fibers of the copy paper. Although it is more efficient than other fixing methods, the solvent vapor scatters and creates an odor. It is not widely used due to many hygiene problems.

In addition, the pressure fixing method is a method of applying mechanical force to the toner to adhere the toner to the copy paper, and it has the advantage of being able to fix with less energy and being able to start quickly and at high speeds. , the fixing properties are worse than those of other fixing methods, and the pressure-sensitive toner has the disadvantage that its manufacturing method is complicated and expensive.
The reality is that it has not been widely put into practical use.

Therefore, for fixing unfixed toner images, a heat fixing method is generally used in which the toner is melted by heating and adhered to the copy paper.

Conventionally, this heat fixing method is a heat roll method in which fixing is carried out by applying a constant pressure between a pair of rolls (fixing roll and pressure roll) that are heated to at least one force and passing the copy paper carrying the unfixed toner image. This is the most widely used method because it has advantages over other heat fixing devices, such as lower power consumption and less risk of fire due to paper jams in the fixing section.

As this fixing roll, polytetrafluoroethylene (trade name: Teflon), ITV silicone rubber,
A roll whose surface is coated with a heat-resistant release material such as RTV silicone rubber is used, and one pressure roll is coated with HTV silicone rubber or the like in order to have a certain contact width when it comes into pressure contact with the fixing roll. LTV silicone rubber, RTV silicone rubber, fluororubber, EPD
A rubber (EthylenePropylene D
A material made of a heat-resistant elastic material such as iene acrylic rubber) is used.

However, the biggest drawback of this heat roll method is that the toner side of the copy paper comes into direct contact with the surface of the fuser roll, so some of the unfixed toner on the copy paper is transferred to the fuser roll side, and that toner is transferred to the copy paper. A so-called offset phenomenon occurs in which the toner is retransferred to the trailing edge of the copy paper or to the copy paper that passes next, staining the copy paper.

To prevent this phenomenon, a method has been adopted in which a release agent such as silicone oil is applied to the surface of the fixing roll, but this requires a tank for storing the oil and equipment for applying the oil, making the equipment more complicated. Not only does this result in an increase in size, but the oil also stains the copy paper.

For this reason, recently, methods have been developed to use a Teflon-treated silicone roll as a fixing roll and allow silicone oil to seep out from the roll surface during use, and toner contains treated substances such as low-molecular-weight polyethylene, low-molecular weight polyethylene, polypropylene, etc. that improve mold release properties. A fixing device that does not require a supply device for a release agent such as oil has been put into practical use by using a method in which a release agent such as oil is included in advance.

However, in fixing devices that do not apply these mold release agents,
Compared to devices that apply a release agent, there is a disadvantage that floating toner present inside the main body of a copying machine or the like easily adheres to and accumulates on the surface of the fixing roll or pressure roll, especially as shown in Figure 1. There was a tendency for the toner to accumulate in the areas on both sides of the fixing roll (1) where there was little chance of contact with the copy paper (2).

Therefore, when copying a large original, the toner (3) accumulated on both sides of the fixing roll (1) may be transferred to the copy paper and stain the copy paper.
In extreme cases, the unfixed toner on the copy paper and the toner (3) deposited on the fixing roll (1) fuse with each other, resulting in the copy paper being wound around the fixing roll (1).

Additionally, as shown in Figure 2, there is a cleaning roll (4) for cleaning toner etc. adhering to the surface of the fixing roll (1).
In the fixing device equipped with the above-mentioned fixing roll (1
) The toner accumulated on both sides of the cleaning roll (4) is cleaned and transferred onto the cleaning roll (4).
) Toner may accumulate on both sides, causing the center of the cleaning roll (4) to float, or the accumulated and solidified toner may damage the surface of the fixing roll (1), causing the copy paper to There are disadvantages such as poor toner adhesion and wrinkles on the copy paper, and these disadvantages also occur when a cleaning device using heat-resistant felt or the like is used instead of a cleaning roll. It was something that happened.

[Purpose of the invention]

The present invention eliminates and improves these drawbacks of the prior art.In a fixing device consisting of a fixing roll and a pressure roll, the entire surface of the fixing roll and pressure roll is covered with a cover to prevent the adhesion of floating toner. However, it is an object of the present invention to provide a fixing device that can provide copies with stable image quality over a long period of time.

[Structure of the invention]

That is, the present invention provides a fixing device that fixes toner by passing between a fixing roll and a pressure roll, in which a cover covering the entire surface of the fixing roll and pressure roll is disposed, and Passage openings for the copy paper to pass through are formed on the front and rear sides, and through holes are formed on both sides through which the rotation shafts of the rolls pass, thereby preventing floating toner from adhering to the surfaces of the rolls. prevent,
This makes it possible to obtain stable copies over a long period of time.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

3 shows a perspective view of the fixing device of the present invention, and FIG. 4 shows an explanatory sectional view thereof.

That is, the fixing device of the present invention includes a fixing roll (5), a pressure roll (6), and each roll +5 as shown in FIG.
) +6) covers (71+81).

First, the fixing roll (5) is moved as shown by arrow A in FIG.
A cylindrical core metal (9) is rotatably supported in a direction, and RTV silicone rubber covering the surface of this core metal (9), H
It consists of a heat-resistant elastic layer (1o) made of TV silicone rubber, fluororubber, EPDA rubber, etc., and a heater (ill) for heating the fixing roll (5) is disposed within the core metal (9). .

On the other hand, the pressure roll (6) is provided below the fixing roll (5), and like the fixing roll, it has a cylindrical core bar (12) and the heat-resistant elastic layer (12) covering the surface of the core bar (12).
I3), the core metal (I2) is rotatably supported in the direction of arrow B with the rotation of the fixing roll (5), and the fixing roll (5) and the pressure roll (6
) Appropriate pressure is applied between them by a mechanism not shown.

The fixing roll (5) and the pressure roll (6) are provided with a passage opening, that is, a gap, for passing the copying Be (144), and a cross section that covers the entire surface thereof from above and below along the longitudinal direction. Roughly U-shaped cover (71
(81 is arranged, and the front surface (1) of the cover (7)
5), the lower end side of the rear surface (I6) and the front surface of the cover (8) (
The upper end sides of Iη and the rear surface (I8) are each bent inward, so that their tips approach the surfaces of the rolls +51 +6+.

Note that four notches (not shown) are formed on the lower end side of the rear surface (16) of the cover (7), and when the rear surface (16) is bent inward on the lower end side, the fixing roll (5) )
The copy paper separation claw (1g) provided in the copy paper separation claw (1g) is configured to fit into the four notches.

Further, as shown in Fig. 3, through holes (A) and (A) are formed in both left and right sides of the cover +71 and +8) (the right side is not shown), respectively. Rotating shafts (c) (c) of roll (5) and pressure roll (6)
It is structured so that it penetrates through.

The cover is made of metal such as aluminum or heat-resistant plastic, and the outside thereof is covered with heat-resistant felt or the like to prevent burns. Furthermore, by pasting a double-insulated layer on the inside of the cover, it is possible to increase the heat retention efficiency of the fixing roll and reduce energy consumption.

To fix the toner using the fixing device of the present invention, as shown in FIG. The unfixed toner is then passed between a fixing roll (5) and a pressure roll (6), thereby melting the unfixed toner and flowing it into the fibers of the copy paper (14), cooling it and fixing it.

At this time, the above-mentioned cover is placed on the surface of the fixing roll (5) etc.
+71 (Due to the action of 81, there is no accumulated toner due to the adhesion of floating toner, so the copy paper (14) is not smeared with accumulated toner or wrapped around the fixing roll (5), etc., unlike in the past. .

In FIG. 4, (c) indicates a cleaning roll, which cleans toner and the like that have landed on the surface of the fixing roll (5).

Here, in this embodiment, a cover having a substantially U-shaped cross section is used, but the cover used in the present invention is not limited to this shape. For example, the above-mentioned fixing device that does not use a cleaning roll In this case, a cover having a substantially semicircular cross section may be used to reduce the space between each roll and the cover.

Further, in this embodiment, each roll is covered with separate covers from the top and bottom, but the present invention is not limited to this method. For example, as shown in FIG. Cover the entire surface of each roll with the rectangular parallelepiped cover (A), and
Each side has an opening shaft (
B) Configuration C2, in which passage openings are opened from 1 to 1, and through-holes 030 → are opened on both sides 02 (the right side is not shown) of the cover (A), through which the rotation shafts of the rolls pass through. Of course it's fine.

Further, for convenience of explanation, the present invention has been explained using a heat roll type fixing device as an example, but the fixing device of the present invention is not limited to a heat roll type fixing device, but a roll type fixing device using a pressure fixing method. (- is also used as a matter of course.
-I can do something.

〔Effect of the invention〕

As described above, the floating toner existing inside the main body of a copying machine etc. does not easily adhere to the fixing roll and pressure roll, so the floating toner adheres to both sides of the fixing roll and accumulates, unlike in the conventional case. There's nothing to do.

Therefore, not only can various troubles caused by floating toner accumulated on the fixing roll be eliminated, but also the existence of the cover reduces heat loss of the fixing roll, improving energy efficiency, etc. The practical effects of the invention are enormous.

[Brief explanation of the drawing]

1 and 2 show a plan view and a side view, respectively, of a conventional fixing device, and FIGS. 3 to 5 show embodiments of the present invention, and FIG. 3 shows the fixing device of the present invention. 4 shows a side explanatory view thereof, and FIG. 5 shows a perspective view of a fixing device according to another embodiment. Code explanation (11 (51...Fuser roll +21 +14
1... Copy paper (3)...) -1
1--(41(c)...Cleaning roll (
6) Pressure roll [71 (81@7)...
...Cover (9) (12) ... Core metal +1
it)+13)...Heat-resistant elastic layer (lυ...
...Heater f15+ +1η (c)...
Front + 16) 1B) (c) ... Rear + 19)
・・・・・・Copy paper separation claw @)Qυ0→・・・・・・
・On the side) 0 罎 (B)...Through hole (C) (
C)...Rotating shaft (7)0])...Opening 496- Fig. 1

Claims (1)

[Claims] In a fixing device that is provided inside the main body of an electrophotographic copying machine or the like, and passes a copy sheet on which an unfixed toner image is formed between a fixing roll and a pressure roll to fix the toner, the above-mentioned fixing roll and The pressure roll is provided with a cover that covers the entire surface thereof, and passage openings through which the copy paper passes are formed on the front and rear sides of the cover, and
A fixing device characterized in that a through hole is provided on both side surfaces through which the rotating shaft of each of the rolls passes.