JPH08146796A - Fixing device - Google Patents

Abstract

(57) [Abstract] [Purpose] A fixing device that heats and fixes an unfixed developed image by pressing it through a heat-resistant film sheet to reduce power consumption and warm-up time. The force required to drive the film sheet may be small, and there is no sliding part, which prevents wear of the heating element and the like. [Structure] The heat-resistant film sheet 6 absorbs infrared light emitted from the halogen lamp 4 to raise its temperature. The film sheet 6 is driven to rotate, and the toner 20 of the unfixed visible image is
The recording medium 22 carrying is moved while being in contact with the film sheet 6, and heat is applied to the toner 20 to fix the toner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus such as a copying machine, a printer, a facsimile machine, etc. The present invention relates to a fixing device that heats and fixes a recording medium onto a recording medium.

[0002]

2. Description of the Related Art Conventionally, as a fixing device in an image forming apparatus using electrophotography, a heat roller system using a halogen lamp as a heat source has been widely adopted. This heat roller type fixing device will be described below with reference to FIG. The fixing device of this type includes a heating roller 104 having a halogen lamp 102 built therein as a heat source, and a pressure roller 106 that is in pressure contact with the heating roller 104.
The heating roller 104 absorbs the radiant heat generated by the light emission of the halogen lamp 102 to raise the temperature to the proper fixing temperature, and the toner image 108 is carried between the heating roller 104 and the pressure roller 106 which are rotationally driven in the arrow direction. By heating the recording medium 110 while sandwiching and conveying the recording medium 110, the toner image 108 is fixed to the recording medium 110.
The temperature sensor 11 is placed in contact with the heating roller 104.
2 is attached, and the amount of electric power applied to the halogen lamp 102 is feedback-controlled by detecting the temperature of the heating roller 104. Also, the heating roller 1
On the surface of 04, a peeling layer 114 made of a fluorine-based resin or the like is formed to prevent the toner and the recording medium 110 from adhering to and wrapping around the heating roller 104. The fixing device using the heat roller method has an advantage that the structure is relatively simple, but the heat efficiency is low, and the heating roller 10 is activated after the halogen lamp 102 starts to conduct electricity.
There is a problem that it takes a long time for the toner No. 4 to reach a predetermined temperature suitable for fixing the toner.

Therefore, in order to solve this problem, a recording material carrying an unfixed image is carried through a thin heat-resistant film which is conveyed while pressing the heat of a fixed heating body against the heating body. A method has been proposed in which the unfixed image is heated and fixed by applying it to the. A fixing device using this heat resistant film will be described with reference to FIG. In this type of fixing device, a resistance heating element 202 is built in, and a heating element unit 206 in which an endless belt-shaped heat-resistant fixing film 204 is wound and stretched around an outer peripheral portion, and a heating element unit via this fixing film 204. A recording medium 2 having a driving pressure roller 208 provided so as to be in pressure contact with 206, and carrying a toner image 210 on the heating body unit 206 side between the fixing film 204 and the driving pressure roller 208.
12 is carried in. Then, by rotating the driving pressure roller 208 in the arrow direction, the fixing film 204 is rotated in the arrow direction at the same speed as the conveyance speed of the recording medium 212 in conjunction with this. The heating unit 2
Reference numeral 06 denotes a heat insulating material 2 for guiding the rotation of the fixing film 204.
14 and a temperature sensor 216 that detects the temperature of the resistance heating element 202. The temperature sensor 216 detects the temperature of the resistance heating element 202 and the resistance heating element 202 is controlled so that the temperature is controlled within a set temperature range. The power supplied to the is adjusted.

In such a structure, the toner image 21
Recording medium 212 carrying 0 on the heater unit 206 side
Is carried in between the fixing film 204 and the driving pressure roller 208, and the toner image 210 is fixed by receiving heat from the heating unit 206 while overlapping with the fixing film 204. The rotationally driven fixing film 204 passes through the pressure contact portion between the heating body unit 206 and the driving pressure roller 208, and then the traveling direction changes at a steep angle, so that the recording medium 212 having been fixed is separated from the fixing film 204. In the fixing method using such a heat-resistant fixing film 204, since the thin film 204 is used, the temperature of the pressure contact portion of the heating body unit 206 with the driving pressure roller 208 rapidly rises, and the temperature suitable for fixing is reached. It takes less time, and at the same time, power consumption can be reduced. Further, there is also known a flash lamp type fixing device in which infrared rays emitted from a flash lamp are used as a heat source, and the toner absorbs light from the flash lamp to fix a toner image (for example, Japanese Utility Model Laid-Open No. 59-683).
No. 71).

[0005]

However, in the apparatus for heating and fixing using the fixing film 204 as described above, the resistance heating element 202 is slid in contact with the fixing film 204, and therefore, the driving is performed. Since it is necessary to increase the torque of the pressure roller 208 and the resistance heating element 202 is also worn, there is a problem that a material resistant to wear must be used as the resistance heating element 202 in order to increase durability. . Further, in the above-mentioned flash lamp type fixing device, since the absorptance of the flash lamp light varies depending on the density of the toner, the fixability may be uneven. The present invention has been made to solve the above-described problems, and has a simple configuration without losing the advantages of low power consumption and a short time required to reach a temperature suitable for fixing. It is an object of the present invention to provide a fixing device which can increase durability and can perform uniform fixing.

[0006]

In order to achieve the above object, the fixing device according to the invention of claim 1 has a lamp for emitting a light beam, and the light beam emitted from the lamp to a recording medium carrying an unfixed visible image. And a heat-resistant film sheet that absorbs light emitted from a lamp and rises in temperature in a fixing device that heats and fixes an unfixed visible image on the recording medium,
A transport means for transporting the recording medium while bringing the recording medium into contact with the film sheet. Further, in the fixing device of the invention of claim 2, in the structure of claim 1, the film sheet is brought into close contact with the unfixed visible image on the recording medium in the fixing portion which receives the light beam from the lamp, and the same as the recording medium. It is conveyed at a speed. Further, in the fixing device of the invention of claim 3, in the structure according to claim 1 or 2, the film sheet is made of a resin material in which carbon is dispersed.

[0007]

In the fixing device having the above structure, the light rays emitted by the lamp are absorbed by the heat-resistant film sheet and converted into heat, so that the temperature of the film sheet rises. The unfixed visible image carried on the recording medium is conveyed while contacting the film sheet, whereby the unfixed visible image receives heat energy from the film sheet and is fused and fixed. At this time, the heat energy is uniformly received regardless of the toner density of the image. There is no part where the film sheet slides on the heating element, etc., and wear does not occur. Further, in the fixing device according to the second aspect, the film sheet is in close contact with the unfixed visible image at the fixing portion of the unfixed visible image on the recording medium, and is integrally conveyed at the same speed to conduct heat. Therefore, a uniform fixing action can be obtained. Further, in the fixing device according to the third aspect, since the film sheet is made of a resin material in which carbon is dispersed and is black, the heat energy is efficiently received from the film sheet.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of the fixing device according to the present embodiment, showing a state in which a recording medium is inserted and fixing is performed. The fixing device 2 includes a halogen lamp 4 and
An endless sheet-shaped fixing film 6 stretched rotatably so as to surround the halogen lamp 4,
The fixing film 6 is wound and supported by holding rollers 8 and 10 which are provided at a predetermined interval for forming the fixing unit 7, a tension roller 12, and a driving roller 14. Further, pressure rollers 16 and 18 are arranged to face the holding rollers 8 and 10, and the pressure rollers 16 and 1 are provided.
8 and the fixing film 6 between the unfixed visible image toner 2
A recording medium 22 such as a recording paper carrying 0 is fed by a conveying means (not shown). The toner 20 surface of the recording medium 22 is fed upward, and the toner 20 surface comes into contact with the fixing film 6. The rotatably driven fixing film 6 and the pressure rollers 16 and 18 also function as means for conveying the recording medium 22. Further, the halogen lamp 4 is provided with a reflecting plate 24 for irradiating the fixing film 6 passing through the fixing portion 7 with the reflected light so that the reflected light of the emitted light contributes to the fixing of the toner 20. Has been done.

Since the fixing film 6 absorbs infrared rays of the light from the halogen lamp 4, converts the infrared rays into heat, and transfers the heat to the toner 20, heat resistance is required. In addition, it is necessary to efficiently absorb the light (infrared ray) from the halogen lamp 4, and it is preferable that the thickness is as thin as 20 to 100 μm in order to improve the thermal efficiency. Therefore, for example, a polyimide resin material in which carbon is dispersed can be used as a material having a certain level of strength and infrared absorption characteristics. Further, since the surface of the fixing film 6 on the recording medium 22 side is in direct contact with the toner 20, it is preferable to use a composite film having a fluororesin layer on the surface in order to improve releasability.

Next, the fixing device 1 configured as described above.
Will be described. When the fixing operation is started, the halogen lamp 4 is energized, the halogen lamp 4 emits light, and the driving roller 14 is rotationally driven, so that the fixing film 6 is rotated in the arrow direction. The infrared light of the halogen lamp 4 is, together with the light from the reflection plate 24, the fixing unit 7 between the holding rollers 8 and 10.
Is absorbed by the fixing film 6 passing through the fixing unit 7 and converted into heat, and the temperature of the portion of the fixing film 6 which receives the infrared light rises. Further, when the recording medium 22 carrying the toner 20 is carried in between the holding rollers 8 and 10 and the pressure rollers 16 and 18 by the conveying means, the recording medium 22
Is in close contact with the fixing film 6 and conveyed at the same speed, and receives heat from the fixing film 6 during that time. As a result, the temperature of the toner 20 rises, so that the toner 20 is melted and fixed on the recording medium 22. The recording medium 22 is separated from the fixing film 6 after passing through the holding roller 10. Further, by providing the fluorine resin layer on the surface of the fixing film 6, the toner 20 is separated from the fixing film 6 while remaining on the recording medium 22 side without adhering to the fixing film 6 side. That is, since the toner 20 does not adhere to the fixing film 6, the toner 20 does not adhere to the fixing roller 6.
The toner 20 is prevented from adhering to the back side of the recording medium 22 to be conveyed next time from the pressure rollers 16 and 18 and becoming dirty, without being transferred to the 6 and 18 sides.

In the fixing device 1 according to the above embodiment, since the fixing film 6 is a thin member and has a small heat capacity, the fixing lamp 6 absorbs the light from the halogen lamp 4 and quickly rises in temperature, so that the temperature of the halogen lamp 4 is increased. The power consumption is small, and the time required from the start of conduction of the halogen lamp 4 to the temperature suitable for fixing is shortened. Further, since the heating element does not come into contact with the fixing film 6, the force for driving the fixing film 6 is small, and the heating element is not worn. Further, since the toner 20 is heated uniformly regardless of its density, uniform fixing is possible.

Although the embodiments of the present invention have been described above, modifications can be made without departing from the spirit of the present invention. For example, a lamp other than the halogen lamp 4 may be used as long as it can efficiently radiate infrared rays, and the xenon lamp may be intermittently driven. The drive roller 14 and the tension roller 12 may be the same roller. Further, as the fixing film 6, other than the polyimide resin material in which carbon is dispersed, any material can be used as long as it is a film material containing a black dye.

[0013]

As described above, according to the fixing device of the first aspect of the invention, the recording medium is conveyed while being contacted with the heat-resistant film sheet that absorbs the light emitted from the lamp and rises in temperature, and is undetermined. Since the image-fixed image is fixed, the time required to reach the temperature suitable for fixing can be made extremely shorter than in the conventional case, and the power consumption can be reduced. Moreover, since the heating element does not come into contact with the film sheet and there is no sliding portion, the driving force of the film sheet can be small, and the heating element or the like is not worn.
The durability can be improved. Further, the unfixed visible image is heated regardless of its density, and uniform fixing can be performed, so that an image having very good image quality after fixing can be obtained. According to the fixing device of the second aspect of the invention, in addition to the above effects, the film sheet is brought into close contact with the unfixed visible image on the recording medium and is conveyed at the same speed as the recording medium. It is possible to carry out even fixing without any trouble. Also,
According to the fixing device of the third aspect of the present invention, since the film sheet is made of the resin material in which carbon is dispersed, the temperature can be efficiently raised, and the effect of reducing the power consumption and the warm-up time can be remarkably obtained. To be

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a fixing device according to an exemplary embodiment of the present invention.

FIG. 2 is a sectional view showing an example of a conventional fixing device.

FIG. 3 is a sectional view showing another example of a conventional fixing device.

[Explanation of symbols]

 2 Fixing device 4 Halogen lamp 7 Fixing unit 6 Fixing film (film sheet) 20 Toner 22 Recording medium

Claims (3)

[Claims] 1. A fixing device having a lamp for emitting a light beam, and irradiating a light beam emitted from the lamp to a recording medium carrying an unfixed visible image to heat and fix the unfixed visible image on the recording medium. 2. A fixing device, comprising: a heat-resistant film sheet that absorbs a light beam emitted from the lamp to raise a temperature; and a transporting unit that transports the recording medium while bringing the recording medium into contact with the film sheet. 2. The film sheet is brought into close contact with an unfixed visible image on the recording medium in a fixing section that receives a light beam from the lamp, and is conveyed at the same speed as the recording medium. The fixing device according to item 1. 3. The fixing device according to claim 1, wherein the film sheet is made of a resin material in which carbon is dispersed.