JPH08234618A - Fixing device - Google Patents

Abstract

PURPOSE: To perform excellent fixing by eliminating the unevenness of temperature distribution in the axial direction of a rotating body for fixing in an image recorder. CONSTITUTION: This fixing device is provided with a pair of rotating bodies 1 consisting of the rotating body for fixing and a rotating body for pressuring. In the device, a heater F is used inside at least either of the rotating bodies 1, and the rotating body 1 is heated by the heater F. By changing the absorptivity of radiant energy from the heater F on the inner surface of the rotating body by respective parts 2, 3, 4, 5, 6 and 7 in the axial direction of the rotating body, the temperature distribution in the axial direction of the rotating body is made uniform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a rotating body pair having a fixing rotating body and a pressing rotating body used in an image recording apparatus such as a copying machine and a laser beam printer, and at least one rotating body is provided. The present invention relates to a fixing device that heats using radiation from a halogen heater.

[0002]

2. Description of the Related Art As shown in FIG. 2, a rotating body for fixing or a rotating body for pressurization is provided inside a rotating body 16 having a metal surface coated with resin, rubber or the like, which extends along the axis of the rotating body. The heater 17 is inserted, and the radiant heat from this heater is absorbed by the inner surface of the rotating body to raise the temperature of the surface of the rotating body to an extent sufficient to fix the recording material.
It has a structure. The heater is composed of a unit of a winding wire of a conductive wire called a filament, and radiation rays are mainly radiated from this filament portion. By adjusting the arrangement of the filaments, it is possible to change the distribution of radiant energy applied to the inner surface of the rotating body.

At this time, in order to improve absorption of radiant heat on the inner surface of the rotor, a material having a radiation absorption rate close to 1.0 is recoated over the entire surface.

When heating the inside of the fixing rotator or the pressure rotator using radiation from the reheater, the rotation contacting the recording material is performed in order to stabilize the fixing state of the image fixed on the recording material. It is necessary to keep the temperature distribution on the outer surface of the body constant within the rotating body.

However, in a general rotating body which is heated, as shown in FIG.
Equipped with a holding member indicated by 19, heat escapes to the end holding portion through the path of the dotted line in the figure.

As shown in FIG. 3, the central portion 20 of the rotor receives radiation from the filaments 24, 25, and 26, while the end portion 21 of the rotor receives filament 23.
Radiation from the filaments 24 and 25 is blocked by the convex portion 22 at the end and reaches only the radiation rays from the filaments 24 and 25.

Therefore, the radiant energy applied to the inner surface of the rotor from each filament of the heater is smaller at the end of the rotor than at the center of the rotor.

For these reasons, the temperature of the outer surface of the rotating body has a distribution in which the central portion is high and the end portions are low.

In the conventional fixing device, as a means for avoiding the decrease in the surface temperature of the end portion in the axial direction of the rotating body, the arrangement or length of the heater filaments should be close to the end portion of the rotating body as shown in FIG. By doing so, a method of increasing the supply of heat to the ends has been proposed.

Specifically, among the winding parts 27 to 31 of the filament forming the heater in FIG. 4, the winding parts 27, 28 at the ends are made longer than the winding parts 29, 30, 31 at the center. Alternatively, a method of narrowing the interval to make the density denser is used.

By using this method, the temperature difference between the central portion and the end portion of the rotating body is eliminated to some extent. However, in this method, the radiant energy from the heater is used not only to raise the temperature of the fixing execution unit 32 in the figure which contacts the recording material and actually controls its fixing, but also to raise the temperature of the end portions of 33 and 34 in the figure. It has been destroyed and is inefficient in terms of energy. Further, this method does not completely eliminate the non-uniformity of the temperature distribution on the outer surface 32 in the axial direction of the rotating body.

[0012]

In the above conventional example, even if the filament distribution of the heater is closely adjusted at the end of the rotor, the temperature at the end of the rotor tends to be lower than that at the center. Poor fixing may occur at the end portion during continuous paper feeding. Further, the heat energy of the heater is wastefully consumed at the end, and the thermal efficiency of heating the heater deteriorates.

As described above, it is difficult to solve the problem of the end temperature drop only by disposing the filament of the heater.

An object of the present invention is to solve the above problems and to provide a fixing device in which the axial distribution of the temperature of the rotating member is properly adjusted.

[0015]

In order to achieve the above object, a first invention according to the present application comprises a rotating body pair having a fixing rotating body and a pressing rotating body, and at least one of the rotating bodies. In a fixing device that uses a heater inside a rotating body and heats the rotating body by absorbing radiant energy emitted from the heater on the inner surface of the rotating body, the absorption rate of the radiant energy on the inner surface of the rotating body changes in the axial direction of the rotating body. By doing so, the temperature distribution in the axial direction of the rotating body is made uniform.

According to a second aspect of the present invention, in the fixing rotator, two or more kinds of coating materials having different absorptivities are applied in a predetermined pattern on the inner surface of the rotator to obtain a temperature distribution in the axial direction of the rotator. It is characterized by being arbitrarily adjusted.

[0017]

【Example】

<Embodiment 1> FIG. 1 is a sectional view of a fixing rotator according to Embodiment 1 of the present invention.

In the figure, reference numeral 1 denotes a rotating body, and 2 to 7 denote respective portions of the rotating body 1 made of metal. Also 8 ~ 13
Indicates the state of the coating material applied to the inner surface of the rotor or the inner surface of the rotor.

Generally, a black substance having an absorptivity of 0.9 or more (for example, Okitsumo or the like) is applied to the entire inner surface of the fixing rotator, but in the present invention, the central portions 3 and 6 of the inner surface of the rotator in the drawing are shown. , Coating material 1 to be applied to the inner end portions 2, 4, 5, 7 of the rotating body
The coating materials 9 and 12 having a lower absorptance than the radiation absorptances of 1, 13, 14, and 15 are applied (however, the rotor end portion 2,
The absorptivity of the material applied to 4, 5, and 7 is 0.9 or more).

Alternatively, the inner surfaces of the central portions 3 and 6 of the rotating body are not coated with the material, and the metal surface of the rotating body is exposed, or the surface of the exposed surface is processed to have a rough surface. Compared with the above, the absorption rate of the metal surface should be higher.

Furthermore, the boundary between the two surfaces having different absorptances may be changed in a granular manner or may be clearly separated.

By the above treatment, the radiant energy radiated from the filament F is absorbed by the coating material 8, 10, 11, 13 at the end portion of the rotor 1 by 90% or more, and the rotor end portions 2, 4, 5, 7 are absorbed. Raise the temperature of. On the other hand, a part of the radiation radiated from the filament F to the central portion 3 of the inner surface of the rotor is absorbed there and used to raise the temperature of the central portion 3 of the rotor, but since the absorptivity of the coating material is not high, the radiation is Is reflected and irradiated to another inner surface of the rotating body, for example, 11 and 13, and contributes to the temperature rise of the rotating body end portions 5 and 7. Similarly, with respect to the radiation emitted from the filament F to the surface 12 inside the rotor, a part of the radiation is applied to another inner surface of the rotor, for example, the coating materials 8 and 10. Therefore, in terms of the end portions 2 and 4 of the rotor, the radiation directly radiated from the filament F to the coating materials 8 and 10 and the radiation from the filament to the inner surface 6 of the rotor are reflected and the coating material 8 and
Both of the radiation emitted to 10 are used to raise the temperature of the rotor ends 2, 4.

From the above, the thermal energy applied to the central portion of the rotating body is smaller than that at the end portion of the rotating body, and the temperature rise in the central portion, which has been mentioned above as a problem, is prevented. By adjusting the areas of the two regions having different radiation absorptances, it becomes possible to make the heating temperature of the central portion and the end portion of the rotating body substantially uniform.

Further, even if there is a slight temperature difference between the central portion and the end portion of the rotating body during heating, since the rotating body is made of a metal having good thermal conductivity, as shown by the dotted arrows 14 and 15 in FIG. Heat conduction occurs in the axial direction of the rotating body, and the temperature at the end and the temperature at the center are made uniform.

According to the above principle, the disadvantage that the temperature of the central portion of the rotating body becomes higher than that of the end portion in the conventional method is solved. Also, unlike the conventional method, it is not necessary to make the filament distribution of the heater denser at the end in order to prevent the temperature drop at the end, so the thermal efficiency used to raise the temperature of the rotating material recording material passage part of the heater wattage is increased. It is possible to raise.

<Embodiment 2> FIG. 5 illustrates the concept of the second embodiment. The material to be applied to the inner surface 46 of the cylindrical surface of the fixing rotator through which the recording material passes does not apply to the entire inner surface, but is applied in stripes as indicated by 35 to 45 in FIG. 35 here
˜40 is a portion to be coated with a coating material having a radiation absorption rate of 0.9 or more (hereinafter, the surface state of this portion is referred to as surface state A), 4
1 to 45 is the area where the coating material is not applied, or the area where the absorption rate is 35 to 40 is smaller than the area where the coating material is applied (hereinafter, the surface state of this portion is referred to as surface state B) is there.

By coating two or more kinds of materials having different absorptivities on the surface of the rotating body in a specific pattern, it is possible to provide an arbitrary temperature distribution in the axial direction of the outer surface of the rotating body. For example, the amount of radiant heat absorbed from the heater is large in the surface state A region, and the amount of radiant heat absorbed in the surface state B region is low.

Therefore, the surface state A has a large area at the end of the inner surface of the rotor, and the surface state A gradually increases toward the center of the rotor.
It is possible to improve the phenomenon that the central portion temperature rises, which is a problem of the general fixing rotary body, by making the area of 2) smaller and the area of the surface state B larger, and to make the axial temperature distribution of the fixing rotary body uniform. it can.

Further, the temperature distribution in the axial direction of the fixing rotator can be adjusted by combining the surface condition A and the surface condition B in an appropriate ratio. Therefore, if this method is used, a certain temperature distribution in the axial direction can be obtained. It becomes easy to design such a fixing rotating body.

[0030]

As described above, the rotating body is provided with the rotating body pair having the fixing rotating body and the pressing rotating body, and the heater is used inside at least one rotating body of the rotating body pair. In the fixing device, the temperature of the outer surface of the rotating body can be adjusted by changing the radiation absorptance in the axial direction of the surface of the rotating body, and a sufficient amount of heat can be supplied to the unfixed image passing through the end of the rotating body for stable fixing. Can provide images.

[Brief description of drawings]

FIG. 1 is a diagram showing a method of applying a coating material on the surface of a fixing rotator according to the present invention and a flow of radiant heat from a filament.

FIG. 2 is a cross-sectional view of a general rolling element on a plane parallel to the rotation axis, showing the heater filament, the position of a holding portion of the rotating element, the direction of heat escape, and the like.

FIG. 3 is a diagram showing a state in which radiant heat is supplied from a filament at an end of a general fixing rotator.

FIG. 4 is a view for explaining the arrangement of heater filaments that supply heat to a general fixing rotary member.

FIG. 5 is a diagram showing an example of a coating pattern of a coating material on the surface of the fixing rotator according to the present invention.

[Explanation of symbols]

1 ... Rotating body, 3,6 ... Central part of the rotating body, 2,4
5, 7 ... Ends of the rotating body, 8, 9, 10, 11, 12,
13 --- Coating material, 23, 24, 25, 26 --- Filament

Claims (2)

[Claims] 1. A rotator pair having a fixing rotator and a pressing rotator, wherein a heater is used inside at least one of the rotators, and radiant energy emitted from the heater is absorbed on the inner surface of the rotator. In the fixing device for heating the rotating body by doing so, the temperature distribution in the rotating body axial direction is made uniform by changing the absorption rate of the radiant energy on the inner surface of the rotating body in the rotating body axial direction. . 2. In the fixing rotator, the temperature distribution in the axial direction of the rotator is arbitrarily adjusted by applying two or more kinds of coating materials having different absorptivities on the inner surface of the rotator in a predetermined pattern. The fixing device according to claim 1.