JP2714204B2 - Fixing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device that is used in a copying machine, an optical printer, or the like and heats and fixes a toner image on a recording material.

[Prior Art] Conventionally, a means using a heat roller is widely used as a means for fixing a toner image on a recording material. However, power consumption is increased, and a temperature at which fixing can be performed after a switch is turned on. In some cases, the time until the arrival (weight time) becomes long.

The applicant has previously proposed in Japanese Patent Application Laid-Open No. 63-313182 a fixing device which solves this problem, and which can achieve low power consumption and a large reduction or elimination of the wait time by using a fixed heating element and a thin film. .

[Problems to be Solved by the Invention] However, in the fixing device using the fixed heating element and the film, only the heating unit is in a high temperature state and the other parts are in a cold state.

This is particularly noticeable at the first fixing after the main switch is turned on.

In heat fixing, the moisture contained in the paper evaporates due to the fixing heat and becomes steam, filling the inside of the fixing unit. is there.

If condensation forms on the film or condensed on other members grows and becomes water droplets and drops on the recording material or film, the fixed image becomes stained with water droplets (flowing pattern)
And image defects sometimes occurred.

In particular, when the film is driven by a roller, the roller is in a cold state immediately after the fixing device is started, so that the film is cooled and easily dewed.

When the film is in the form of an endless belt, and has a deviation control mechanism for controlling the deviation of the film, the coefficient of friction between the water and the heat-resistant endless film changes due to the adhesion of water droplets to the rollers and the heat-resistant endless film. In some cases, the balance was lost, and the film was shifted to one side, so that a normal fixing operation could not be performed.

[Means for Solving the Problems] In order to solve the above problems, the present invention relates to a heating member and a heating member which slides on one surface with the heating member and contacts the recording material bearing the unfixed image on the other surface. A fixing device, comprising: a moving film; and a driving roller that contacts the film and drives the film. The fixing device fixes an unfixed image on a recording material by heat from the heating body through the film. It is characterized by having a blowing means for blowing a drying wind in the vicinity.

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

FIG. 2 is a sectional view of an image forming apparatus to which the fixing device according to the embodiment of the present invention is applied.

Reference numeral 1 denotes a document table made of a transparent member such as glass, which scans a document by reciprocating in the direction of arrow a. A short-focal small-diameter imaging element array 2 is disposed immediately below a document table, and a document image placed on the document table 1 is illuminated by an illumination lamp 3, and a reflected light image is formed by the array 2 on a photosensitive drum. 4 is subjected to slit exposure. The photosensitive drum 4 rotates in the direction of arrow b. Reference numeral 5 denotes a charger, which uniformly charges the photosensitive drum 4 covered with, for example, a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer. On the drum 4 uniformly charged by the charger 5, an electrostatic image subjected to image exposure by the element array 2 is formed. The electrostatic latent image is visualized by a developing device 6 using a toner made of a resin or the like that softens and melts when heated. On the other hand, cassette S
A sheet P, which is a recording material stored in the drum, is transported by a pair of transport rollers 8 which are pressed and rotated in a vertical direction at a timing synchronized with a feed roller 7 and an image on the photosensitive drum 4 to form a drum. 4 is sent on. Then, the toner image formed on the photosensitive drum 4 is transferred onto the sheet P by the transfer discharger 9. Thereafter, the sheet P separated from the drum 4 by a known separating unit is guided to a fixing device 11 by a conveyance guide 10 and subjected to a heat fixing process, and then is discharged onto a tray 12. After the transfer of the toner image, the residual toner on the drum 4 is removed by the cleaner 13.

 FIG. 3 is an enlarged view of the fixing device 11 of the present embodiment.

Reference numeral 14 denotes a low-heat-capacity linear heating element fixedly supported by the apparatus, which is formed by coating a resistance heating material 16 to a 1.0 mm width on an alumina substrate 15 having a thickness of 1.0 mm, a width of 10 mm and a length of 240 mm as an example. Energization that is more energized is DC 100 V cycle 20 msec
A pulse corresponding to a desired amount of temperature energy release controlled by the temperature detecting element 17 with a pulse-like waveform of the above-mentioned form is given by changing the pulse width, and the approximate pulse width is 0.5 msec to 5 msec.

In this way, the fixing film 18 moves in the direction of the arrow in the drawing while coming into contact with the heating element 14 whose energy and temperature are controlled. As an example of this fixing film, a heat-resistant film having a thickness of 20 μm, for example, polyimide, polyetherimide, PES, PFA at least on the image contacting surface side was coated with a 10 μm release layer obtained by adding a conductive material to a fluororesin such as PTFE and PAF. It is an endless film. The total thickness is preferably less than 100μ, especially less than 40μ. The film drive is driven roller 19 and driven roller 20
It moves without wrinkles in the direction of the arrow due to the drive and tension caused by. Reference numeral 21 denotes a pressure roller having a rubber elastic layer having good releasability, such as silicon rubber, which presses the heating body through the film with a total pressure of 4 to 7 kg and rotates by pressing against the film.

Further, a shift control mechanism (not shown) is provided to prevent the position of the film from shifting in a direction perpendicular to the moving direction of the film.

The unfixed toner on the sheet P is guided to a fixing unit by an entrance guide, and a fixed image is obtained by the above-described heating.

FIG. 1 is an enlarged sectional view of an embodiment of the present invention. Reference numeral 22 denotes a guide plate for guiding the sheet, which serves as a guide for accurately turning the sheet to the fixing unit. 23 is a paper discharge roller. 24 is a cross-flow fan driven by a dedicated small motor. This fixing device is applicable to all devices that form an image using a toner, such as a copying machine, a printer, and a facsimile.

When a main switch (not shown) is turned on, a copy button is pressed, and an image forming signal is input, energization of the resistance heating material 16 and the illumination lamp 3 is started, and at the same time, the cross flow fan 24 rotates in the direction of arrow A. A flow in the direction of arrow B is generated, and wind is blown in the vicinity of the drive roller 19 (the wind is high and dry because the temperature in the operating image forming apparatus rises). By blowing the wind, dew condensation generated near the drive roller 19 can be evaporated.

 Next, another embodiment will be described.

 FIG. 4 is a sectional view of another embodiment of the present invention.

In the present embodiment, an exhaust port of the cooling fan 25 of the main body is enlarged so that wind is blown to the vicinity of the drive roller 19. The fan rotates in the direction of arrow C, draws in air from the direction of arrow D, blows out the air in the directions of arrows E and F, and evaporates dew condensation near the drive roller 19. In this embodiment, since the fan 25 has both the function of cooling the main body and the function of discharging ozone outside the main body and the condensation and evaporation, there are also merits of cost reduction and miniaturization.

Fifth is a cross-sectional view of still another embodiment, in which the cross-flow fan 26 draws in the heated air near the lamp 27 of the optical unit (not shown) from the direction of arrow H and rotates the fan 26 (direction of arrow G). The mechanism blows out in the direction of arrow I. In this way, the heated and dried air is
As a result, the dew near the fixing device can be evaporated. Also, not limited to lamps in the optical section,
Heated air in the vicinity of a heat source such as a power supply unit, an electrical unit, and a motor unit may be sucked in the same manner as described above.

FIG. 6 is a perspective view showing still another embodiment of the present invention.

FIG. 6 shows an embodiment in which the motor fan 27 blows air in the longitudinal direction (the direction of arrow J) of the drive roller 19 to evaporate dew condensation.

[Effects of the Invention] According to the present invention, it is possible to prevent dripping of a water droplet on a recording material or transmission of a water droplet to a film to reach a fixing portion, thereby significantly affecting an image. In addition, the coefficient of friction between the water and the roller changes as the water drops adhere to the roller or film, causing the imbalance of the heat-resistant endless film to break, causing breakage or wrinkles, making it impossible to fix, or fixing. Disturbing images can be prevented.

[Brief description of the drawings]

1 is a cross-sectional view of a fixing device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of an image forming apparatus to which the fixing device of the embodiment of the present invention is applied, and FIG. 4 and 5 are enlarged sectional views of a fixing device according to still another embodiment of the present invention. FIG. 6 is a perspective view of a fixing device according to still another embodiment of the present invention.
It is. 14 Heating element 18 Heat-resistant endless film 19 Drive roller 20 Driven roller 21 Pressure roller 24, 25, 26 Cross flow fan 27 Motor fan

Claims (2)

(57) [Claims] 1. A heating member, a film having one surface sliding with the heating member and the other surface moving together with a recording material bearing an unfixed image, and a driving device for contacting the film and driving the film. A fixing device for fixing an unfixed image on a recording material by heat from the heating element via the film, further comprising: a blower that blows dry air near the driving roller. Fixing device. 2. The image forming apparatus according to claim 1, wherein said fixing device is applied to an image forming apparatus having an unfixed image forming means for forming an unfixed image on a recording material, and said drying air is air cooled by said image forming device. The fixing device according to claim 1, wherein the fixing device is a fixing device.