JPH0623904B2 - Fixing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention compresses and heats unfixed developer (toner powder) on an image bearing member (recording paper) in an information recording device such as a facsimile, a copying machine, and a printer. The present invention relates to a heat-compression type fixing device for fixing.

Configuration of Conventional Example and its Problems With the recent remarkable development of an information recording apparatus, a demand for improving the image quality of a recorded matter has increased, and stable and high quality toner powder fixing has become necessary. 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, and 1 is a heating roller,
It 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. These heating rollers 1
The pressure roller 6 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. In this state, when the recording paper 9 holding the toner powder 5 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 discharged. While passing through, it is melted under pressure and heat and fixed on the recording 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, is discharged to the outside from the gap of the nip portion 10, and the portion of the recording paper 9 before entering into the nip portion 10 absorbs this steam. Since it rushes into the nip portion 10 in a state of being absorbed and expanded, there is a problem that paper wrinkles easily occur on the recording paper after fixing.

An object of the present invention is to eliminate the above-mentioned conventional drawbacks. When an image carrier (recording paper) holding a developer such as toner powder passes through the nip portion, it is heated to be vaporized and discharged. By sucking the water content of the image carrier by the air suction means provided in the vicinity of the nip portion, a paper wrinkle is generated because the unfixed portion of the image carrier absorbs the water vapor and expands to enter the nip portion. It is an object of the present invention to provide a fixing device that prevents the occurrence of wrinkles and does not cause paper wrinkles during fixing.

To achieve the above object, the fixing device of the present invention is a means for melting and fixing the developer on the image carrier by heating and compressing the image carrier holding a developer such as toner powder. And an air suction means having an opening substantially opposite to the heating / compressing portion is provided in the vicinity of the portion immediately before the image bearing body plunges into the heating / compressing portion. When passing, the moisture contained in the image carrier discharged from the heated image carrier as water vapor is sucked by the air suction means.

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 and the pressure roller 6 are provided in the same manner as in the conventional example, and an air suction pump 11 and an air suction duct 12 are provided in the vicinity of the entrance of the recording paper 9 between these rollers 1 and 6. Means are provided so that the water vapor discharged from the nip portion 10 is concentrated and stably sucked from the tip opening 13 of the air suction duct 12 provided substantially opposite to the nip portion 10. . In order to clarify the effect of the air suction means, its operation will be described in comparison with the conventional example with reference to FIGS. In FIG. 3, a
Shows the case of the conventional example, b shows the case of the embodiment according to the present invention, in each of a and b, I is before the recording paper 9 enters the nip portion 10, and II is the recording paper 9 at the nip portion 10. In the middle of passing through the recording medium 3, III shows 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 by the heating roller 1 and the pressure roller 6 to become water vapor, which is outside the nip portion 10. Is discharged to. 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. The recording paper 9 is the nip
While passing through 10, as shown in a, steam is mainly discharged in the four directions of a, b, c, and d, but the amount of discharge in the a and b directions is smaller than that in the c and d directions. The main discharge direction of water vapor is concentrated in the direction C and the direction D on the entry side of the recording paper 9. b shows a state in which the water vapor in the two directions is sucked from the air suction duct 12 of the air suction means. In this case, the water vapor in the two directions is removed, and the degree to which the recording paper 9 gets wet and expands before entering the nip portion 10 becomes extremely small. Although it is possible to suck the water vapor from the direction C, it was confirmed that the one-way suction in the two directions is sufficiently effective. Therefore, as shown in II of FIG. 3, in the case of the conventional example of a, the recording paper 9 absorbs the generated water vapor and expands immediately before the nip portion 10 to swell, resulting in the recording paper 9 being swollen. Wrinkles occur as shown in III of a. On the other hand, according to the embodiment of the present invention shown in b, the recording paper 9 does not swell due to hygroscopicity, and the wrinkle-free fixing 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. In FIG. 5, the difference from the first embodiment is that the pressure roller 6 is replaced by two shafts.
An endless belt 16 having a width substantially the same as that of the heating roller 1 is provided so as to be freely wound by 14, 15 and the endless belt 16 is pressed against the heating roller 1 and interlocks with the rotation of the heating roller 1. To wind. Water vapor generated when the recording paper 9 holding the toner powder 5 passes through the pressure contact portion [nip portion 17] between the heating roller 1 and the endless belt 16 is sucked by the air suction means including the air suction duct 12 and the suction pump 11. As a result, paper wrinkles do not occur during fixing, and the same effect as in the first embodiment can be obtained.

EFFECTS OF THE INVENTION As described above, the present invention comprises means for melting and fixing the developer on the image carrier by heating and compressing the image carrier holding the developer such as toner powder. Is provided with an air suction means having an opening substantially opposite to the heating / compressing portion in the vicinity immediately before entering the heating / compressing portion, and is heated when the image carrier passes through the heating / compressing portion. By collecting the water content of the image carrier discharged as water vapor from the image carrier by the air suction means and stably sucking it, the water vapor is absorbed by the unfixed portion of the image carrier as in the conventional case. However, it is possible to realize a fixing device capable of preventing the unfixed portion from being moistened and expanded 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, 6 ... Pressure roller, 7 ... Pressure roller base material, 8 ...... Elastic layer, 9 ...
… Recording paper, 10 …… Nip part, 11 …… Air suction pump, 12
…… Air suction duct, 13 …… Opening part, 14, 15 …… Shaft, 16
…… Endless belt, 17 …… Nip part

Front page continuation (72) Inventor Koji Koshigashi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-57-198480 (JP, A) JP-A-55-161738 (JP) , A) Actual opening Sho-58-105562 (JP, U) Actual opening Sho-59-138870 (JP, U) Japanese Patent Sho 57-3943 (JP, B2) Japanese Official Sho 52-33494 (JP, B2)

Claims (1)

[Claims] 1. A means for melting and fixing the developer on the image carrier by heating and compressing the image carrier holding a developer such as toner powder, wherein the image carrier is a heating / compressing unit. The air suction means having an opening substantially opposite to the heating / compressing portion is provided in the vicinity of the portion just before entering into the heating / compressing portion. A fixing device, characterized in that the air sucking means sucks the water vaporized and discharged.