JPH0548202Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application This invention relates to a fixing unit of an image forming apparatus that is equipped with a static elimination brush that contacts a conductor portion on the surface of a fixing roller to eliminate static from the surface of the roller.

(b) Prior Art Generally, in an electrophotographic copying machine, an electrostatic latent image formed on the surface of a photoreceptor in an exposure process is visualized using a developer such as toner in a development process. Furthermore, the toner image on the surface of the photoreceptor is transferred onto paper by corona discharge or the like. At this time, the charge that has been charged on the paper by the transfer charger is removed by the neutralization charger. This makes it easier to separate the paper from the surface of the photoreceptor, but if the charge from the transfer is not removed sufficiently and the paper remains on the paper, the paper will be affected by static electricity during the next fixing process. It gets stuck to the fixing roller. For this reason, conventionally, as shown in FIG. 3, a charge eliminating brush 33 is brought into contact with a conductor portion 32 on the surface of the fixing roller, excluding the fluororesin layer 31 that fixes the image on the paper, to indirectly remove the charges on the paper from the roller surface. I am trying to remove it.

(c) Problems to be solved by the invention However, in the conventional fixing unit mentioned above,
Because the static eliminating brush does not come into direct contact with the paper, the charges on the paper are not sufficiently eliminated, and the static electricity caused by the paper's charges causes the paper to stick to the fixing roller, making it difficult to peel off the paper smoothly.

In addition, as shown in Japanese Utility Model Application No. 60-193563, a grounded needle-like electrode is provided at the lower part of the paper output side of the fixing roller to contact the back surface of the paper and the surface of the lower roller, thereby eliminating static from both the paper and the fixing roller. However, with this device, there is a problem that static electricity is removed from the paper after fixing, so the toner image before fixing is disturbed by static electricity on the paper during fixing, and the ground electrode is connected to the fixing roller. Since it is provided at the lower part of the paper output side, there was a possibility that the paper after fixing would get stuck to this needle-like electrode, causing a paper jam.

In view of the above-mentioned problems, the purpose of this invention is to eliminate static electricity from the surface of the paper and roller so that the unfixed toner image on the paper is not disturbed, and to smoothly separate the paper from the fixing roller. The purpose of this invention is to provide a fixing unit for

(d) Means for solving the problem This idea consists of a fixing roller with a fluororesin layer formed on the roller surface except for both ends of the roller made of a conductor, and a fixing roller that ejects paper from the lower part of the paper output side of the fixing roller. In the image forming layer fixing unit, the fixing unit for the image forming layer is provided with a paper conveyance path provided toward the end of the roller, and a static elimination brush that comes into contact with the conductor portions at both ends of the roller and eliminates the electric charge charged on the fluororesin layer. A part of the surface of the sheet is made to face the position of the void part of the paper, and the static elimination brush is brought into contact with the position of the void part of the paper surface on which the toner image is formed on the paper input side to the fixing roller.

(e) Effect In the fixing unit of the image forming apparatus according to this invention, when the paper passes through the fixing roller, the paper void portion faces the conductor portion on the surface of the roller, and
On the side where the paper enters the fixing roller, the static elimination brush comes into contact with the voids on the surface of the paper on which the toner image has been formed.
Due to the contact of the static eliminating brush, the electric charge accumulated on the paper is removed before fixing. This charge removal before fixing can prevent unfixed toner from being disturbed during charge removal. Further, after the paper has passed, the static elimination brush comes into contact with the conductor portion on the surface of the roller. This contact removes the charge that has been placed on the roller surface by the paper.

In other words, the static elimination brush alternately contacts the paper and the roller surface, preventing unfixed toner from being disturbed.
The charge on the paper and roller surfaces is removed. Also,
Since there is no electrode for eliminating static electricity at the lower part of the fixing roller on the paper output side, paper jams due to this electrode do not occur. This eliminates the adsorption effect between the paper and the fixing roller, prevents paper jams on the output side of the paper, and allows smooth separation of the paper from the fixing roller.

(f) Embodiment FIG. 2 is a schematic sectional view showing a fixing section and a paper discharge section of an image forming apparatus which is an embodiment of this invention.

The fixing section and paper ejection section are located in frame 1 in the image forming device.
It is attached to 1. The frame 11 is arranged one after the other, and FIG. 2 shows the frame afterwards.

A pair of paper ejection rollers 24 are attached to the left side between the front and rear frames 11, and a paper ejection tray 25 is provided at the lower left of the paper ejection roller 24 and projects diagonally upward to the left. The paper ejecting section consists of:

Also, a paper conveyance path 26 is provided on the right side of the paper ejection roller 24.
is placed, and further to the right side is frame 1.
A pair of upper and lower fixing rollers 21, 1 are pivotally supported on the fixing roller 1 so as to be in pressure contact with each other.

The upper fixing roller 21 has a heater lamp 22 housed inside the hollow roller. Heater lamp 2
2 heats the roller surface and fixes the image on the paper together with the pressure applied by the upper and lower fixing rollers. At the lower left of the upper fixing roller 21, a peeling claw attachment shaft 23a is provided with a peeling claw 23 that comes into contact with the roller surface. The peeling claw 23 peels off the paper adsorbed to the fixing roller and drops it onto the paper conveyance path 26.
Guide to the paper ejection section.

Also, on the upper right side of the lower fixing roller 1 on the paper input side, there is a static eliminating brush 2 that contacts the surface of the lower fixing roller 1.
is installed. The upper and lower fixing rollers 21,
1. The peeling claw 23 and the static eliminating brush 2 constitute a fixing section. Reference numeral 27 denotes a paper guide that guides the paper 3 on the upper surface of which a toner image is formed by transfer to the fixing section in the direction of arrow L.

Next, the arrangement of the lower fixing roller 1 and the static elimination brush 2 will be explained with reference to FIG. 1.

FIG. 1 is a plan view showing the arrangement of the lower fixing roller 1 and the static eliminating brush 2. As shown in FIG.

The surface of the lower fixing roller 1 includes a fluororesin layer 1a formed at the center of the roller surface and serving as a fixing portion for an image;
It is comprised of aluminum base portions 1b with exposed aluminum bases on both sides of the fluororesin layer 1a.

Further, the width of the fluororesin layer 1a is shorter than the width A of the paper 3 by the paper void width B, as shown in the figure.
Further, the left paper void portion 3b of the paper 3 is formed so as to contact the left aluminum base portion 1b of the fixing roller 1.

On the other hand, the static elimination brush 2 is attached to a brush mounting member 20 fixed to the left side frame 11 from the inside with screws in FIG. are in contact.

With this configuration, the tip of the static eliminating brush 2 comes into contact with the paper void portion 3b when the paper passes, and after the paper passes, it comes into contact with the aluminum base portion that is the conductor on the roller surface.

Due to the contact of this static elimination brush, the electric charge on the paper is removed before it enters the fixing unit when the paper passes through.
After the paper passes, the charge on the roller surface due to contact with the paper is removed from the aluminum base portion. Therefore,
It is possible to prevent the unfixed toner from being disturbed in the fixing section, and it is also possible to reliably eliminate the electric charge on the roller surface.

In this way, the static elimination brush 2 comes into contact with the electrical charge on the paper and the conductor on the surface of the roller, which is charged due to contact with the paper. Since the static electricity removal effect is increased by the amount of static electricity removed directly, the adhesion effect due to static electricity between the paper and the fixing roller is eliminated, and the separation of the paper becomes smooth.

(g) Effect of the invention As described above, according to this invention, when paper passes through the fixing roller, the paper void faces the conductor on the surface of the roller, and the toner image is formed on the side where the paper enters the fixing roller. The static elimination brush comes into contact with the voids on the surface of the paper where the . Further, after the paper has passed, the static elimination brush comes into contact with the conductor portion on the surface of the roller. Therefore, the electric charge on the paper is directly removed from the paper by the antistatic brush before fixing when the paper passes, and it is possible to prevent the unfixed toner image from being disturbed by the static electricity on the paper during fixing, and also to In this case, the electric charge that is generated when the paper comes into contact with the roller surface is eliminated by the neutralization brush, so that the adhesion of the paper to the fixing roller is eliminated, and the paper is effectively peeled off from the fixing roller more smoothly.
Furthermore, since the static eliminating brush is provided on the paper input side of the fixing roller, paper jams do not occur unlike devices in which the static eliminating brush is provided on the paper output side.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a lower fixing roller and a static elimination brush of a fixing unit according to an embodiment of this invention. FIG. 2 is a schematic cross-sectional view showing a fixing section and a paper discharge section of an image forming apparatus equipped with the same fixing unit. FIG. 3 is a plan view showing a lower fixing roller and a static elimination brush of a conventional fixing unit. 1... Lower fixing roller (fixing roller), 1a...
Futsuso resin layer, 1b...aluminum base part (conductor part),
2... Static elimination brush, 3... Paper, 3a... Paper void portion, A... Paper width, B... Paper void width.

Claims (1)

[Scope of Claim for Utility Model Registration] A fixing roller that is made of a conductor and has a fluorine resin layer formed on its surface except for both ends, and a fixing roller that is provided from the bottom of the paper output side of the fixing roller toward the paper output section. In a fixing unit of an image forming apparatus, which is provided with a paper conveyance path and a static elimination brush that comes into contact with the conductor parts at both ends of the roller and eliminates the electric charge charged on the fluororesin layer, a part of the surface of the conductor part is attached to the paper. A fixing unit for an image forming apparatus, characterized in that the static elimination brush is opposed to a void part position and is brought into contact with a void part position on the surface of a sheet on which a toner image is formed on the paper input side to a fixing roller.