JPH0887196A - Fixing device - Google Patents

Abstract

PURPOSE: To prevent a pressure roller from being damaged by the friction of a foreign matter intervening in a cleaning nip by allowing an edge coated with a coating material of fluororesin to abut on the surface of the pressure roller, thereby forming the cleaning nip. CONSTITUTION: A cleaning blade C1 is provided with a long plate state elastic member 61, a rubber member 62 covering one long side of the member 61 in a longitudinal direction and having a square cross section, the edge 62a of the rubber member 62, and the coating material 63 of the fluororesin coating over the entire length of the edge 62a in the longitudinal direction. The edge 62a is allowed to abut on the surface of the pressure roller 10b, so that the cleaning nip N is formed. The elastic member 61 is constituted of a metallic plate and the coating material 63 is constituted of a heat resistant Teflon(R) tape. Since the cleaning blade C1 is constituted in such a way, the pressure roller 10b is prevented from being damage for the reason that the foreign matter such as paper powder and offset toner intervening in the cleaning nip N rubs the roller 10b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device mounted on an image forming apparatus such as a copying machine or a laser beam printer.

[0002]

2. Description of the Related Art A fixing device mounted on an image forming apparatus such as a laser beam printer generally forms a fixing nip by bringing a pressure roller into contact with a fixing roller containing a heater. Further, the fixing roller is coated with a release agent for the purpose of preventing toner offset and improving the releasability, and the pressure roller is intended to remove the release material, paper dust and offset toner. The cleaning blade is in contact.

[0003]

However, the cleaning performance greatly changes due to a slight change in the material of the cleaning blade or the contact pressure, and for example, foreign matter such as paper dust or offset toner adheres to the edge of the cleaning blade. As a result, there is a problem that the pressure roller is damaged and the image on the surface contacting the pressure roller is disturbed during double-sided image formation.

Therefore, an object of the present invention is to provide a fixing device that solves the above problems.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a pressure roller is brought into contact with a fixing roller to form a fixing nip, and a releasing agent is applied to the fixing roller. In a fixing device in which a cleaning blade is brought into contact with the pressure roller while applying, the cleaning blade includes a long plate-shaped elastic member and a rectangular cross section that covers one long side of the elastic member along the longitudinal direction. Of the rubber-like member and a fluororesin-based covering material covering the edge of the rubber-like member over the entire length in the longitudinal direction, and the edge covered with the fluororesin-based covering material is provided on the surface of the pressure roller. The cleaning nip is formed by being brought into contact with each other.

In this case, the fluororesin coating material is
A heat resistant tape coated with an adhesive can be used.

Further, it is preferable that the tape covers the entire rubber-like member.

The tape may be extended from both ends in the longitudinal direction of the rubber-like member to provide extension portions, and the extension portions may be closed by the adhesive.

Further, the mounting angle of the cleaning blade with respect to the tangent line of the pressure roller may be set to 20 to 60 degrees.

The amount of the cleaning blade entering the surface of the pressure roller is set to 0.4 to 1.7 mm, or the linear pressure of the cleaning blade to the surface of the pressure roller is set to 30 to 40 g / cm. Can be set.

The cleaning nip may be provided in the upper half of the pressure roller.

[0012]

According to the above construction, the edge covered with the fluororesin-based coating material is brought into contact with the surface of the pressure roller to form the cleaning nip, whereby the edge of the cleaning blade is protected from paper dust, offset toner, etc. It prevents foreign matter from adhering and allows an appropriate amount of release agent to pass through the cleaning nip.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view showing a schematic structure of a digital four-color full-color image forming apparatus as an example of an image forming apparatus equipped with a fixing device according to the present invention.

The image forming apparatus shown in the figure has a lower digital color image printer section (hereinafter simply referred to as "printer section") I and an upper digital color image reader section (hereinafter simply referred to as "reader section") II. For example, the printer unit I forms an image on the recording material P based on the image of the document D read by the reader unit II.

The structure of the printer unit I and the structure of the reader unit II will be briefly described below.

The printer section I has a photosensitive drum 1 as an image carrier which is driven to rotate in the direction of arrow R1. Around the photosensitive drum 1, a primary charging device (charging device) 2, an exposure device 3, a developing device (developing device) 4, a transfer device 5, a cleaning device 6, a pre-exposure lamp 7, and the like in order along the rotation direction. Are arranged. Below the transfer device 5, that is, in the lower half portion of the printer unit I, a paper feed / conveyance unit 8 for the recording material P is arranged, and further above the transfer device 5, a separating means 9 is provided, and a downstream side of the separating means 9. A fixing device 10 and a paper discharge unit 11 are arranged (downstream in the transport direction of the recording material P).

The photosensitive drum 1 has a drum-shaped substrate 1a made of aluminum and an OPC (organic optical semiconductor) photosensitive member 1b covering the surface thereof, and is driven in a predetermined direction in the direction of arrow R1 by driving means (not shown). It is configured to be rotationally driven at a process speed (peripheral speed). The photosensitive drum 1 will be described in detail later.

The primary charger 2 has a shield 2a having an opening at a portion facing the photosensitive drum 1, and a discharge wire 2b arranged inside the shield 2a in parallel with a generatrix of the photosensitive drum 1.
And a grid 2c arranged in the opening of the shield 2a to regulate the charging potential. A charging bias is applied to the primary charger 2 by a power source (not shown), so that the surface of the photosensitive drum 1 has a predetermined polarity,
It is designed to be uniformly charged to a predetermined potential.

The exposure means 3 includes a laser output section (not shown) that emits a laser beam based on an image signal from a reader section II, which will be described later, a polygon mirror 3a that reflects the laser beam,
It has a lens 3b and a mirror 3c. The exposure means 3 is
By irradiating the surface of the photosensitive drum 1 with this laser light, the photosensitive drum 1 is exposed, and the charges in the exposed portion are removed to form an electrostatic latent image. In this embodiment, the electrostatic latent image formed on the surface of the photosensitive drum 1 is separated into four colors of yellow, cyan, magenta, and black on the basis of the image of the original, and the electrostatic latent image corresponding to each color is separated. The images are formed sequentially.

The developing device 4 includes four developing devices in order from the upstream side along the rotation direction of the photosensitive drum 1 (direction of arrow R1), that is, yellow, cyan, magenta, and black colors each made of resin as a base. It is provided with developing devices 4Y, 4C, 4M, and 4Bk that store toner (developer). Each of the developing devices 4Y, 4C, 4M, and 4Bk has a developing sleeve 4a for adhering toner to the electrostatic latent image formed on the surface of the photosensitive drum 1, and has a predetermined color used for developing the electrostatic latent image. Of the developing device is alternatively arranged at a developing position close to the surface of the photosensitive drum 1 by the eccentric cam 4b,
Toner is attached to the electrostatic latent image via the developing sleeve 4a to form a toner image (visible image) as a visible image. The three color developing devices other than the developing device used for development are retracted from the developing position.

The transfer device 5 includes a transfer drum (recording material carrier) 5a for supporting the recording material P on its surface, a transfer charger (transfer charging means) 5b for transferring the toner image on the photosensitive drum 1 to the recording material P, and It has an attraction charger 5c for attracting the recording material P to the transfer drum 5a, and an attraction roller 5d, an inner charger 5e, and an outer charger 5f facing the attraction charger 5c, which are rotatably supported in the direction of arrow R5. A recording material carrying sheet 5g made of a dielectric material is integrally stretched in a cylindrical shape in the peripheral opening area of the transferred drum 5a. Recording material carrying sheet 5g
Uses a dielectric sheet such as a polycarbonate film. The transfer device 5 is configured to adsorb and carry the recording material P on the surface of the transfer drum 5a.

The cleaning device 6 includes a cleaning blade 6a for scraping off the residual toner remaining on the surface of the photosensitive drum 1 without being transferred to the recording material P, and a cleaning container 6b for collecting the scraped toner.

The pre-exposure lamp 7 is arranged adjacent to the upstream side of the primary charging device 2 and removes unnecessary charges on the surface of the photosensitive drum 1 cleaned by the cleaning device 6.

The paper feeding / conveying unit 8 is provided with recording materials P having different sizes.
A plurality of paper feed cassettes 8a for stacking and storing paper, a paper feed roller 8b for feeding the recording material P in the paper feed cassette 8a, a number of conveying rollers, a registration roller 8c, etc. P is supplied to the transfer drum 5a.

The separating means 9 is a recording material P after the toner image is transferred.
Separating charger 9a for separating the transfer drum 5a from the transfer drum 5a,
It has a separating claw 9b and a separating push-up roller 9c.

The fixing device 10 is provided with a fixing roller 10a having a heater inside and a fixing roller 10a below the fixing roller 10a.
Pressure roller 1 for pressing recording material P against fixing roller 10a
With 0b.

The paper discharge section 11 is arranged on the downstream side of the fixing device 10 and is provided with a conveyance path switching guide 11a and a discharge roller 11.
b, a paper discharge tray 11c and the like. Further, below the transport path switching guide 11a, a transport vertical path 11d for performing image formation on both sides of one recording material P, a reverse path 11e, a stacking member 11f, an intermediate tray 11g, and a transport roller. 11h, 11i, a reversing roller 11j, etc. are arranged.

A potential sensor S ₁ for detecting the charging potential of the surface of the photosensitive drum is provided between the primary charger 2 and the developing device 4 around the photosensitive drum 1, and the developing device 4 and the transfer drum 5a are connected to each other. A density sensor S ₂ for detecting the density of the toner image on the photosensitive drum 1 is arranged between them.

Next, the reader section II will be described.
The reader unit II, which is arranged above the printer unit I, scans the document D.
An original table glass 12a on which a document is placed, an exposure lamp 12b for exposing and scanning the image surface of the original D while moving, a plurality of mirrors 12c for further reflecting the reflected light from the original D, a lens 12d for condensing the reflected light, and It has a full-color sensor 12e that forms a color-separated image signal based on the light from the lens 12d. The color-separated image signal is processed by a video processing unit (not shown) via an amplifier circuit (not shown), and is sent to the printer section I described above.

Next, the operation of the image forming apparatus having the above configuration will be described.
A brief description will be given with some configuration added. In the following description, four full-color images are formed in the order of yellow, cyan, magenta, and black.

The image of the original document D placed on the original platen glass 12a of the reader unit II is illuminated by the exposure lamp 12b and color-separated so that the yellow image is first read by the full color sensor 12e and subjected to predetermined processing. And sent as an image signal to the printer unit I.

In the printer section I, the photosensitive drum 1 is indicated by an arrow R.
It is driven to rotate in one direction, and the surface is uniformly charged by the primary charger 2. Based on the image signal sent from the above-mentioned reader unit II, laser light is emitted from the laser output unit of the exposure unit 3, and the surface of the charged photosensitive drum 1 is exposed by the optical image E via the polygon mirror 3a and the like. To do. Electric charges are removed from the exposed portion of the surface of the photosensitive drum 1, so that an electrostatic latent image corresponding to yellow is formed. In the developing device 4, the yellow developing device 4Y is arranged at a predetermined developing position, and the other developing devices 4C, 4M, 4Bk are arranged.
Is retracted from the developing position. To the electrostatic latent image on the photosensitive drum 1, yellow toner is attached by the developing device 4Y,
The toner image is visualized. The yellow toner image on the photosensitive drum 1 is transferred to the recording material P carried on the transfer drum 5a. As the recording material P, a recording material P having a size suitable for an original image is supplied from a predetermined paper feed cassette 8a to a transfer drum 5a at a predetermined timing via a paper feed roller 8b, a conveyance roller, a registration roller 8c and the like. It is a thing. The recording material P thus supplied is attracted so as to wind around the surface of the transfer drum 5a and rotates in the direction of arrow R5, and the yellow toner image on the photosensitive drum 1 is transferred by the transfer charger 5b. .

On the other hand, the photosensitive drum 1 after the toner image transfer is
The residual toner on the surface is removed by the cleaning device 6, and unnecessary charges are removed by the pre-exposure lamp 7, and the toner is provided for the next image formation starting from the primary charging.

The processes from the reading of the original image by the reader unit II to the transfer of the toner image onto the recording material P on the transfer drum 5a, the cleaning of the photosensitive drum 1 and the removal of the electric charge are other than yellow. Color, ie cyan,
The same applies to magenta and black, and the four color toner images are transferred to the transfer material P on the transfer drum 5a so as to overlap each other.

Recording material P which has been transferred with four color toner images
Is separated from the transfer drum 5a by the separation charging device 9a, the separation claw 9b, and the like, and is conveyed to the fixing device 10 with the unfixed toner image carried on the surface. The recording material P is the fixing device 1.
The toner image on the surface is melted, fixed, and fixed by the transfer roller 10a and the pressure roller 10b of 0. The recording material P after fixing is discharged onto the paper discharge tray 11c by the discharge roller 11b. When images are formed on both sides of the recording material P, the recording material P after the fixing device 10 is discharged.
Is immediately driven to the conveyance path switching guide 11a, and after being guided to the reversing path 11e through the conveyance vertical path 11d,
By the reverse rotation of the reversing roller 11j, the trailing end when fed is made to be the leading end, and it is retracted in the direction opposite to the fed direction and is stored in the intermediate tray 11g. After that, an image is formed on the other surface again by the above-described image forming process, and then the sheet is discharged onto the sheet discharge tray 11c.

In the transfer drum 5a after the separation of the recording material P, in order to prevent scattering of powder on the recording material carrying sheet 5g and adhesion of oil on the recording material P, the recording material carrying sheet 5g is prevented. Fur brush 1 facing each other through
Cleaning is performed by 3a and the backup brush 13b, and the oil removing roller 14a and the backup brush 14b. Note that such cleaning is performed before or after image formation, and at any time when a jam (paper jam) occurs.

Next, the fixing device 10 will be described with reference to FIG.

In the figure, the fixing roller 10a which comes into contact with the toner image includes an HTV (high temperature vulcanization type) silicone rubber layer 32 having a thickness of 1 mm on an aluminum core metal 31, and a specific addition type silicone rubber layer on the outside thereof. With 33, diameter 60m
It is formed in m.

On the other hand, the pressure roller 10b has an HTV of 1 mm thickness and a thickness of 1 mm on the core metal 34 made of aluminum.
mm of the above-mentioned specific addition type silicone rubber layer 35,
It has a diameter of 60 mm.

The above-mentioned fixing roller 10a is provided with a conveying roller heater 36 which is a heat generating means in a core metal 31, and the pressure roller 10b is also provided with a heater 37 in a core metal 34 so that a recording material can be obtained. Heating is performed from both sides of P. The temperature of the pressure roller 10b is detected by the thermistor 38 which is in contact with the pressure roller 10b, and the halogen heaters 36 and 37 are controlled by the controller 39 based on the detected temperature to fix the fixing roller 10a and the pressure roller 10b. Are controlled so that both temperatures are maintained constant at 170 ° C. The fixing roller 10a and the pressure roller 10b are
A total pressure of about 80 kg is applied by a pressurizing mechanism (not shown).

Further, in FIG. 2, O is an oil applying device which is a release agent applying means, C is a cleaning device, and C1.
Is a cleaning blade for removing oil and dirt on the pressure roller 10b. The oil applying device O applies the dimethyl silicone oil 41 in the oil pan 40 to the fixing roller 10a by passing the oil scooping rollers 50, 42 and the oil applying roller 43 to the oil applying amount adjusting blade 44 to regulate the oil applying amount. To do. The cleaning device C cleans the surface of the fixing roller 10a with the web 46 abutted on the fixing roller 10a by the abutting roller 45.

In the fixing device 10 described above, the recording material P having the unfixed toner image on the surface thereof is the fixing roller 1
0a and the pressure roller 10b are nipped and conveyed in the fixing nip, and at this time, the toner is fixed by heating under pressure from both front and back surfaces. At this time, the toners attached to the fixing roller 10a and the pressure roller 10b are removed by the cleaning device C and the cleaning blade C1, respectively.

Next, the cleaning blade C1 which is a feature of the present invention will be described with reference to FIGS. 3 shows a perspective view of the cleaning blade C1, FIG. 4 shows a longitudinal sectional view, and FIG. 5 shows a state where the cleaning blade C1 is brought into contact with the pressure roller 10b.

The cleaning blade C1 has a long plate-shaped elastic member 61, a rubber member 62 having a rectangular cross section that covers one long side of the elastic member 61 along the longitudinal direction, and a rubber member 6.
Two edges 62a, 62a, and a fluororesin-based coating material 63 that covers the entire length in the longitudinal direction. The edge 62a coated with the fluororesin-based coating material 63 is brought into contact with the surface of the pressure roller 10b. Forming a cleaning nip N. The elastic member 61 is composed of a metal plate. Further, in this embodiment, the fluororesin coating material 63 is composed of a heat-resistant tape coated with an adhesive, for example, a Teflon tape. Teflon tape 63
The entire rubber-like member 62 is covered. In the longitudinal direction, as shown in FIG. 3, the rubber-like member 62 is extended from both longitudinal end portions to provide extended portions 63a, and the extended portions 63a are closed by the adhesive. Further, in the width direction, as shown in FIG. 4, the base end side of the rubber-like member 62 is completely covered and attached to the elastic member 61.
As described above, the Teflon tape 63 completely covers the rubber-like member 62 to prevent oil from entering.

Further, the mounting angle θ of the cleaning blade C1 with respect to the tangent line L of the pressure roller 10b is set to 20 to 60 degrees as shown in FIG. 5, and the linear pressure of the cleaning blade C1 at the cleaning nip N is Three
It is set to 0-40g / cm. The linear pressure is 0.4 to 1.7 mm when converted into the amount of entry when the cleaning blade C1 is assumed to be a rigid body. When this value is 0.5 or less, back stain of the recording material P is caused by oil, and when it is 1.5 or more, abdominal contact occurs, and in any case, good cleaning performance is excluded. It Further, it is more preferable to set the above-mentioned mounting angle θ to 30 to 50 degrees and set the entering amount to 0.5 to 1.5 mm.

Furthermore, when the cleaning nip N is provided in the upper half of the pressure roller, the serviceability for replacement and cleaning of the cleaning blade C1 is improved.

The mounting direction of the cleaning blade C1 with respect to the rotation direction of the pressure roller 10a may be either forward or reverse when the image forming apparatus is a single color, while it is preferably forward when the color is color. .

By constructing the cleaning blade C1 as described above, it is possible to prevent the pressure roller 10b from being scratched by foreign matter such as paper dust and offset toner intervening in the cleaning nip N. .

Instead of the above-mentioned Teflon tape 63, for example, a tape made of pyrimido can be used. That is, any other material can be used as long as it can exhibit the performance substantially equivalent to these.

Further, as the fluororesin coating material,
The tape is not limited to the above, and may be formed by coating.

[0052]

As described above, according to the present invention,
By covering the edge of the cleaning blade with a fluororesin-based coating material, it is possible to prevent the pressure roller from being scratched due to paper dust intervening in the cleaning nip and foreign matter such as offset toner rubbing against each other. For example, when a double-sided image is formed, the image on the contact surface of the pressure roller of the recording material is effectively prevented from being disturbed by scratches.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the configuration of a four-color full-color laser beam printer equipped with a fixing device according to the present invention.

FIG. 2 is a schematic diagram illustrating a configuration of a fixing device.

FIG. 3 is a perspective view of the overall configuration of a cleaning blade.

FIG. 4 is a vertical sectional view of a cleaning blade.

FIG. 5 is a vertical cross-sectional view showing a contact state of a cleaning blade with a pressure roller.

[Explanation of symbols]

1 image carrier (photosensitive drum) 2 charging means (primary charger) 3 exposure means 4 developing means (developing device) 5 transfer device 5a recording material carrier (transfer drum) 5b transfer charging means (contact charging member, transfer charging device) , Charging brush) 5g recording material carrying sheet 8 sheet feeding / conveying section 9 separating means 10 fixing device (fixing device) 10a fixing roller 10b pressure roller 11 paper discharging section 61 elastic member (metal plate) 62 rubber-like member 62a edge 63 fluorine Resin type coating material (Teflon tape) 63a Extension part C1 Cleaning blade P Recording material (transfer material)

Claims (8)

[Claims] 1. A fixing device in which a pressure roller is brought into contact with a fixing roller to form a fixing nip, a release agent is applied to the fixing roller, and a cleaning blade is brought into contact with the pressure roller, The cleaning blade includes a long plate-shaped elastic member, a rubber member having a rectangular cross section that covers one long side of the elastic member along the longitudinal direction, and a fluorine member that covers the edge of the rubber member over the entire length in the longitudinal direction. A fixing device comprising a resin-based coating material, and an edge coated with the fluororesin-based coating material is brought into contact with the surface of the pressure roller to form a cleaning nip. 2. The fixing device according to claim 1, wherein the fluororesin-based coating material is a heat-resistant tape coated with an adhesive. 3. The fixing device according to claim 2, wherein the tape covers the entire rubber-like member. 4. The fixing device according to claim 3, wherein the tape is extended from both ends in the longitudinal direction of the rubber-like member to provide extension portions, and the extension portions are closed by the adhesive. . 5. The fixing device according to claim 1, wherein an attachment angle of the cleaning blade with respect to a tangent line of the pressure roller is set to 20 to 60 degrees. 6. The fixing device according to claim 1, wherein an amount of the cleaning blade entering the surface of the pressure roller is set to 0.4 to 1.7 mm. 7. The fixing device according to claim 1, wherein the linear pressure of the cleaning blade with respect to the surface of the pressure roller is set to 30 to 40 g / cm. 8. The fixing device according to claim 1, wherein the cleaning nip is provided in an upper half portion of the pressure roller.