JPH0623905B2 - Fixing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to heat compression for compressing, heating and fixing unfixed toner powder on an image carrier (recording paper) in an information recording apparatus such as a facsimile machine, a copying machine, and a printer. Mold fixing device.

Configuration of Conventional Example and its Problems With the remarkable development of information recording apparatuses in recent years, there is an increasing demand for improvement in image quality of recorded matter, and stable and high-quality toner powder fixing is required. A conventional fixing device will be described below with reference to the drawings. FIG. 1 is a side sectional view of a conventional fixing device. Reference numeral 1 is a heating roller, which is composed of a surface treatment layer 2, a heating roller base material 3, and a heater 4. Here, the heating roller base material 3 is generally made of a metal material such as aluminum. The surface treatment layer 2 is formed by coating the heating roller base material 3 with a material having a good releasability such as a fluororesin in order to improve the releasability from the toner powder 5. The heater 4 is a heat source for heating the heating roller 1, and is controlled to a predetermined temperature by the control circuit. A pressure roller 6 is composed of a pressure roller base 7 and an elastic layer 8, and the elastic layer 8 is generally made of heat-resistant silicon rubber or the like. The heating roller 1 and the pressure roller 6 are in contact with each other with a predetermined pressure contact force applied between their shafts by a spring or the like. The heating roller 1 is rotated by being driven at a predetermined speed by an external drive source (not shown), and the pressure roller 6 is rotated in a direction opposite to that of the heating roller 1 due to a frictional force caused by contact with the heating roller 1. Driven. Recording paper 9 holding toner powder 5 in this state
Is inserted between the contact portions of the heating roller 1 and the pressure roller 6 (hereinafter referred to as the nip portion 10), the toner powder 5 is melted under pressure and heat while passing through the nip portion 10 and is recorded. It is fixed on the paper 9.

The conventional fixing device as described above has a relatively simple structure and is generally widely used.
When passing through the recording paper 9, the water contained in the recording paper 9 becomes steam due to heating and is discharged to the outside from the gap of the nip portion 10, and the unfixed portion of the recording paper 9 before entering the nip portion 10 is Since it rushes into the nip portion 10 in a state where it absorbs water vapor and expands, there is a problem that paper wrinkles easily occur on the recording paper after fixing.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art. An image carrier (recording paper) holding a developer such as toner powder is a pressure contact portion of a roller pair including a first roller and a second roller. When it passes through, the unfixed portion of the image bearing member absorbs the water vapor and rushes into the pressure contact portion in the expanded state by absorbing the moisture content of the image bearing member that is discharged as heating vapor. It is an object of the present invention to provide a fixing device that prevents paper wrinkles from occurring and that does not generate paper wrinkles during fixing.

To achieve the above object, the fixing device of the present invention is configured such that at least one of a pair of rollers consisting of a first roller and a second roller, which are in pressure contact with each other on their outer circumferences, is heated. The image bearing member holding a developer such as toner powder is passed through the pressure contact portion of the roller pair, and the developer is heated and compressed to melt and fix the image bearing member on the image bearing member. When the roller that comes into pressure contact with the developer holding surface is the first roller, the second roller covers the core material, the elastic body layer on the outer peripheral portion of the core material, and the surface of the elastic body layer. It is composed of a fiber layer in which hygroscopic and heat resistant fibers are gathered in a strip shape.

Description of Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a side sectional view of the fixing device according to the first embodiment of the present invention. In FIG. 2, the same reference numerals as those in the conventional example of FIG. 1 represent the same members, and detailed description thereof will be omitted.
That is, the heating roller 1 serving as the first roller is the same as the conventional example, and the pressure roller 11 serving as the second roller has the elastic layer 13 and the hygroscopic property around the roller base material 12 as the strength center of the roller. And a fiber layer 14 in which heat-resistant fibers are gathered in a band shape and are laminated in order. The roller base 12 is made of a metal material such as aluminum, the elastic layer 13 is made of an elastic material such as silicon rubber, and the fiber layer 14 is made of a moisture absorbing material such as a heat resistant cloth or heat resistant paper.

Next, in order to clarify the effect of the fiber layer 14 when the recording paper 9 passes through the pressure contact portion between the heating roller 1 and the pressure roller 11, that is, the so-called nip portion 10, FIG. The operation will be described in comparison with. In FIG. 3, a shows the case of the conventional example and b shows the case of the embodiment according to the present invention. In each of a and b, I is the recording paper 9 before it enters the nip portion 10, and II is the recording paper. 9 is passing through the nip 10 and II
I indicates the state after the recording paper 9 has passed through the nip portion 10.
In both cases a and b, when the recording paper 9 plunges into the nip portion 10,
The moisture contained in the recording paper 9 is heated and compressed in the nip portion 10 to become water vapor, which is discharged to the outside of the nip portion 10.
The discharged state of water vapor is shown in FIGS. 4A and 4B, where a is the case of the conventional example and b is the case of the embodiment according to the present invention. While the recording paper 9 is passing through the nip portion 10, as shown in a, water vapor is mainly discharged in the four directions of a, b, c, and d, but the discharge amount in the b and b directions is the discharge in the c and d directions. The amount of water vapor is smaller than the amount, and the main discharge direction of water vapor is concentrated in the direction C and D on the entry side of the recording paper 9. Reference character b indicates that the water vapor generated in the nip portion 10 is absorbed by the fiber layer 14 on the surface of the pressure roller 11. In this case, the water vapor in the directions B and B is removed, and the amount of water vapor discharged in the directions A and C also decreases because the amount of water vapor absorbed in the direction B and C increases. Therefore, the degree to which the recording paper 9 absorbs water vapor generated from a part of the recording paper 9 which has already plunged into the nip paper 10 to hydrate and expand is very small. As shown in the figure, in the case of the conventional example of a, the recording paper 9 absorbs water vapor and expands immediately before the nip portion 10 to cause a wrinkle, as shown in III of a, while b According to the embodiment of the present invention shown in FIG. 3, the recording paper 9 does not swell due to hygroscopicity, and the fixing without paper wrinkles as shown in III of b) is obtained.

FIG. 5 is a side sectional view of a fixing device according to another embodiment of the present invention. 5 is different from the first embodiment in that the pressure roller 11 is replaced by two shafts 1
An endless belt 17 having a width substantially the same as that of the heating roller 1 is supported by 5 and 16, and the endless belt 17 has hygroscopic and heat-resistant fibers gathered in a strip shape on the outer periphery of the elastic layer 18. The point is that the fiber layers 19 are laminated. The endless belt 17 is pressed against the heating roller 1 and is wound in association with the rotation of the heating roller 1. Water vapor generated when the recording paper 9 holding the toner powder 5 passes through the pressure contact portion [nip portion 20] between the heating roller 1 and the endless belt 17 is absorbed by the fiber layer 19, and paper wrinkles occur during fixing. Without doing so, the same effect as the first embodiment can be obtained.

EFFECTS OF THE INVENTION As described above, according to the present invention, the toner is applied to the pressure contact portion of the roller pair with at least one of the roller pair consisting of the first roller and the second roller that are in pressure contact with each other on their outer circumferences being heated. The developer holding surface of the image carrier is configured to pass through an image carrier holding a developer such as powder and heat and compress the developer to melt and fix the developer on the image carrier. When the first roller is in contact with the first roller, the second roller has a core material, an elastic layer on the outer periphery of the core material, and a hygroscopic and heat-resistant fiber covering the surface of the elastic layer. Since it is composed of a fiber layer that is gathered in a band shape, the waist of the fiber suppresses the deformation of the fiber layer due to pressure and secures a void portion for absorbing water vapor in the fiber layer, and the fiber itself serves as a wall. Water vapor is generated in the voids in the fiber layer formed in the radial direction of the second roller. By securing the air, it is possible to suppress the water vapor discharged from the heated image carrier from moving in the circumferential direction of the second roller and to absorb the water vapor at the water vapor generating position. When the image carrier (recording paper) that holds the image carrier passes through the heating / compressing unit of the fixing device and is absorbed by the fibrous layer to absorb the water content of the image carrier that is discharged as steam by heating, As described above, it is possible to realize a fixing device capable of preventing the unfixed portion of the image bearing member from being moistened and expanded by the water vapor and causing paper wrinkles during fixing.

[Brief description of drawings]

FIG. 1 is a side sectional view of a conventional fixing device, FIG. 2 is a side sectional view of a fixing device in the first embodiment of the present invention, and FIGS.
4A and 4B are explanatory views comparing the effects of the conventional example and the first embodiment of the present invention, and FIG. 5 is a side sectional view of a fixing device in another embodiment of the present invention. 1 ... Heating roller, 2 ... Surface treatment layer, 3 ... Heating roller base material, 4 ... Heater, 5 ... Toner powder, 9 ... Recording paper, 10 ... Nip part, 11 ... Pressurization Roller, 12 ... Roller base material, 13 ... Elastic layer, 14 ... Fiber layer, 15, 16 ... Shaft,
17 …… Endless belt, 18 …… Elastic body layer, 19 …… Fiber layer, 20 …… Nip part.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoji Goto 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 56) References JP-A-51-43941 (JP, A) JP-A-53-89744 (JP, A) JP-A-58-100872 (JP, A) Actually developed JP-A-51-63738 (JP, U)

Claims (3)

[Claims] 1. A developing device for developing toner powder or the like on a pressure-contacting portion of the roller pair, in which at least one of the roller pair consisting of a first roller and a second roller which are in pressure-contact with each other on their outer circumferences is heated. A roller that is configured to pass through the image bearing member holding the developer, heat and compress the developer to melt and fix the developer on the image bearing member, and press-contact with the developer holding surface of the image bearing member. In the case of the first roller, the second roller collects a core material, an elastic body layer on the outer peripheral portion of the core material, and hygroscopic and heat resistant fibers covering the surface of the elastic body layer in a band shape. A fixing device comprising a fiber layer. 2. The fixing device according to claim 1, wherein the second roller is composed of two or more rollers and an endless belt rotatably supported by these rollers. 3. The invention according to claim 1, wherein the fiber layer is made of cloth.
The fixing device according to the item.