JPH0434484A - Fixing device for image forming device - Google Patents

Abstract

PURPOSE:To attract toner in the direction of a form from the back face side and to improve the fixation effect by providing an electret which has the opposite polarity from the toner on the peripheral surface of a pressure roller. CONSTITUTION:The electret 14e which has the opposite polarity from the toner T is provided on the peripheral surface of the pressure roller 14. Therefore, the toner T transferred onto the form P is fixed on the form P by the heat generation of the rotating heat roller 13 and the pressure application of the pressure roller 14 which rotates while pressed against the heat roller 13 and the electret 14e provided on the side of the pressure roller 14 attracts the toner T in the conveyance direction of the form P from its back face side to increase the fixation on the form P more. Consequently, an image of the toner T while holding sharpness can be fixed on the form P with a stronger fixing force.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a fixing device for an image forming apparatus, and more specifically, the present invention relates to a fixing device for an image forming apparatus, and more specifically, a rotating heat roller and a pressure roller that rotates in pressure contact with the heat roller are used to perform transfer. fixing the image on the paper,
The present invention relates to a fixing device of an image forming apparatus.

[Prior Art] Conventionally, a fixing device of an image forming apparatus is composed of an upper rotating heat roller and a lower pressure roller that rotates in pressure contact with the upper heat roller, and the paper is conveyed between the rollers. The transferred image was fixed by applying heat and pressure. .

However, there is a problem in that a portion of the toner unnecessarily adheres to the upper rotating heat roller and rotates, causing image defects due to the so-called fixing offset phenomenon in which the toner is fixed onto the paper again.

As a countermeasure to this, the invention of JP-A No. 60-94479 is
As shown in FIG. 3, in a fixing device 12 consisting of a heat roller 13 and a pressure roller 14, an electret 13e having the same polarity as the toner T is provided on the circumferential surface of the heat roller 13, and the electret 13e having the same polarity as the toner T is used to make the An attempt was made to eliminate the offset phenomenon.

[Problem to be solved by the invention] However, in the case of the above invention, since the temperature of the heat roller 13 is high, the charge of the electret 13e attached to the heat roller 13 easily escapes, and the polarity is stably maintained for a long period of time. The problem was that it was difficult to do so.

Furthermore, since the toner T and the electret 13e are set to have the same polarity, they have the property of repelling each other, and this repulsive force causes the toner T to diffuse onto the surface of the paper P during fixing, resulting in the image being distorted. There was a problem with it being chaotic.

The present invention aims to solve such problems.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides the following fixing device for an image forming apparatus.

That is, the present invention comprises a rotating heat roller and a pressure roller that rotates in pressure contact with the heat roller, and a sheet of paper having a toner image transferred between the two rollers is conveyed to fix the transferred image. The fixing device of the image forming apparatus is characterized in that an electret having a polarity opposite to that of the toner is provided on the circumferential surface of the pressure roller.

[Function] In the above configuration, the toner transferred onto the paper is fixed on the paper by the heating of the rotating heat roller and the pressure of the pressure roller that rotates in pressure contact with the heat roller.

In addition, since the electret provided on the pressure roller side is configured to have the opposite polarity to the toner, it attracts the toner from the back side of the paper in the direction toward the paper, and has the effect of further strengthening the fixation on the paper. do.

[Example] Regarding an example of the present invention, how the configuration of the present invention is actually embodied will be described below with reference to the drawings, along with its operation.

First, FIG. 2 is a schematic explanatory diagram of an embodiment of the present invention,
In the figure, reference numeral 1 denotes a main body of an image forming apparatus, and a rotatable photosensitive drum 2 is provided at the center of the main body 1.

Along the circumferential surface of the photoreceptor drum 2, there is a charging corona discharger 3 for charging the surface of the photoreceptor drum 2, an optical system 4 for irradiating image light to form a latent image, and a toner for forming the latent image. A developing device 5 that visualizes the image, a transfer corona discharger 6 that transfers the image from the photoreceptor drum 2 onto the paper P, a separation corona discharger 7 that separates the transferred paper P from the photoreceptor drum 2, and paper. A cleaning device 8 for cleaning the surface of the photoreceptor drum 2 after P separation, and the like are sequentially arranged clockwise.

Further, at the right end of the figure, there is a paper feed section 9 that supplies paper, and on the left side, downstream of the paper feed section 9, there is a conveyance path 10 that conveys the paper, and the conveyed paper is transferred to the photoreceptor drum. A registration roller 11 is provided between the transfer corona discharger 2 and the transfer corona discharger 6.

The photoreceptor drum 2 is charged by a charging corona discharger 3 while rotating, and then a latent image is formed by irradiation light from an optical system 4, and this latent image is visualized by toner supply from a developer 11i+ device 5. be done.

The fixing device rIi 112 is located on the left side of the separation corona charger 7, that is, downstream thereof, and after stably fixing the transferred toner image onto the paper P, the paper P is discharged to the outside from the discharge section 1a.

FIG. 1 is an explanatory diagram of the fixing device of the same embodiment, and the fixing device 12 includes a rotatable upper heat roller 13 for heating, and a rotatable pressure roller 14 that presses the heat roller 13 from below. It consists of

The heat roller 13 has a Teflon layer 13b on the outer peripheral surface of a cylindrical aluminum base 13a, and has a heating halogen lamp 13C inside.

Further, the pressure roller 14 has a cylindrical aluminum base 14a.
An electret 14e of opposite polarity to the toner T is placed on the outer peripheral surface of the toner T.
It is equipped with

This electret 14e is a polymeric material that can semi-permanently maintain its electrically polarized state at a high voltage.For example, the material itself can maintain its polarity even without connecting a power supply circuit that applies a bias voltage, so It is said that the name electret was given to magnets because it resembles the ability of magnets to maintain their magnetic poles for long periods of time.

This electret i4e has an extremely simple structure and can be made lightweight and compact, so it is a material that has recently come to be frequently used in audio equipment such as ultra-small microphones and speakers as technology advances in the polymer field.

The reason why the electret 14e having such properties is attached to the pressure roller 14 side instead of the heat roller 13 side is that the pressure roller 14 has a lower temperature than the heat roller 13 and maintains polarity stability for a long time. This is not only possible, but also has many advantages as described below, which is the most distinctive feature of the present invention.

When the paper P on which the toner image has been transferred is sent between the heat roller 13 and the pressure roller 14, the paper P
is the heat of the heat roller 13 and the pressure roller 1 that applies pressure from below.
The transferred toner image is fixed on the paper P by the pressure of 4.

When the image of the toner T is fixed, since the Niklet 14e on the pressure roller 14 side is configured to have a polarity opposite to that of the toner T, the toner T is sucked by the Niklet 14e from the back side of the paper P, and as a result, The suction force of the toner T toward the paper P matches the direction of the fixing force, producing a synergistic effect, and the toner image can be reliably fixed on the paper without being diffused.

Therefore, the image created by toner T maintains its clarity,
It is possible to fix the paper P with stronger fixing force.

As described above with respect to the embodiments, the present invention includes an electret having a polarity opposite to that of the toner on the side of the pressure roller in the fixing device of an image forming apparatus consisting of a heat roller and a pressure roller. The toner transfer image is fixed by heating and pressure, and the electret on the pressure roller side attracts toner of the opposite polarity from the back side of the paper toward the paper, so the toner image does not spread on the paper surface. , it is possible to fix the image on paper without distortion and maintaining clarity.

Furthermore, since the electret is provided on the pressure roller side, which has a lower temperature than the heat roller, its polarity can be stably maintained over a long period of time.

[Effects of the Invention] As described above, according to the present invention, the paper conveyed to the fixing device is
The toner transfer image can be fixed on the paper by heating the heat roller and pressing the pressure roller.

Furthermore, since the pressure roller is provided with an electret having a polarity opposite to that of the toner, the toner can be sucked from the back side in the paper direction, thereby further enhancing the fixing effect.

Furthermore, since the suction force of the electret acts in the direction in which the toner is attracted toward the paper, the toner does not adhere to the surface of the heat roller, thus providing an offset prevention effect.

In addition, since the suction force of the electret acts in the direction in which the toner is attracted toward the paper, the image is not disturbed by the electret, and the image quality can be maintained.

Furthermore, since the temperature of the pressure roller is lower than that of the heat roller, the electret provided on the pressure roller side has the advantage of being able to maintain stable electrical polarity.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a fixing device according to an embodiment of the present invention, FIG. 2 is a schematic diagram of an embodiment of the present invention, and FIG. 3 is an explanatory diagram of a conventional example. 12... Fixing device, 13... Heat roller, 14... Pressure roller, 14e... Electret, P... Paper, T... Toner

Claims (1)

[Claims] A fixing device of an image forming apparatus that consists of a rotating heat roller and a pressure roller that rotates in pressure contact with the heat roller, and transports a sheet of paper with a toner image transferred between the two rollers and fixes the transferred image. A fixing device for an image forming apparatus, wherein an electret having a polarity opposite to that of the toner is provided on a circumferential surface of the pressure roller.