JP2002091214A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of attaining high image quality and the reduction of a running cost, and prolonging the life. SOLUTION: As for the image forming device provided with an image forming means 4 for forming an electrostatic latent image corresponding to an image information signal on an image carrier 1, developing the electrostatic latent image by two-component developer constituted of toner particles and carrier particles, forming an unfixed image, and then, transferring the unfixed image to a transfer material, and a fixing means 10 for nipping and carrying the transfer material by a fixation roller 10a and a pressure roller 10b and fixing the unfixed image, the carrier particle is magnetic resin carrier with binder resin formed by a polymerization method, magnetic metallic oxide and non-magnetic metallic oxide, and also, the surface layer material for at least one of the fixation roller and the pressure roller is provided with silicone rubber or fluorine-contained rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copier, a printer, and a recorded image display for forming a visible image by developing an electrostatic latent image formed on an image carrier by an electrophotographic method or an electrostatic recording method. The present invention relates to an apparatus and an image forming apparatus such as a facsimile.

[0002]

2. Description of the Related Art Conventionally, a dry developer as a developer is carried on the surface of a developer carrier, and the developer is transported and supplied to the vicinity of the surface of an image carrier carrying an electrostatic latent image. It is well known that an electrostatic latent image is developed and visualized while an alternating (alternating) electric field is applied between the image carrier and the developer carrier.

The developer carrier is generally referred to as a "development sleeve" in the following description because a developing sleeve is generally used in many cases, and a photosensitive drum is generally used as an image carrier. Therefore, in the following description, it is referred to as "photosensitive drum".

As the above-mentioned developing method, a developer (two-component developer) composed of a two-component system (carrier particles and toner particles) has been conventionally used, particularly in a device for forming a color image, from the viewpoint of the tint of the image. A magnetic brush is formed on the surface of a developing sleeve in which a magnet is disposed, and the magnetic brush is rubbed or brought close to a photosensitive drum which is opposed to the developing sleeve while maintaining a small developing gap. A so-called magnetic brush development method in which development is carried out by continuously applying an alternating electric field between the drums (between S and D) so as to repeatedly transfer and reverse the transfer of toner particles from the developing sleeve side to the photosensitive drum side. It has been known.

The above-described developing device for two-component magnetic brush development mainly has a configuration as shown in FIG. In the figure, 54 is a developing sleeve, 55 is a magnet roller fixedly arranged in the developing sleeve, 58 and 59 are agitating screws, 56 is a regulating blade arranged to form a thin layer of developer on the surface of the developing sleeve 54, 44 Denotes a developing container, and 61 denotes a toner storage room. The developing sleeve 54 is disposed close to the photosensitive drum 1 and rotates in the opposite direction to the photosensitive drum 1 as shown in the figure, so that development can be performed with the developer in contact with the photosensitive drum 1. It is set as follows.

[0006] The two-component developer is supplied to a developing container 44.
Developer 52 in which toner particles and carrier particles are mixed
The ratio of the weight of the toner particles to the total weight of the toner particles and the carrier particles is such that the amount of toner corresponding to the toner consumed by the development drops from the toner storage chamber 61 containing the replenishment toner. It is kept constant by being replenished.

On the other hand, a fixing device mounted on an image forming apparatus such as a copying machine or a printer generally forms a fixing nip by bringing a fixing roller having a heater therein into contact with a pressure roller, and the fixing nip is undetermined. The unfixed toner image is fixed on the recording material as a permanent image by heat and pressure by passing through the recording material carrying the toner image.

The fixing roller and the pressure roller generally have two layers of an elastic layer and a release layer made of silicone rubber or fluorine rubber. When the fixing roller has a release agent application mechanism, an oil-resistant layer may be provided between the elastic layer and the release layer.

In particular, in the case of a color image forming apparatus, since it is necessary to sufficiently melt and mix the toner, a soft roller using an elastic material such as silicone rubber or fluorine rubber is generally used in many cases. From the viewpoint of image quality and toner releasability, relatively soft rubber is used for the surface layers of the fixing roller and the pressure roller.

In recent years, with the spread of color copying machines and color printers, demands for higher image quality and lower running costs have been increasing.

However, the above-described conventional configuration has the following problems.

The irregularities on the surface of the carrier particles are scraped off by friction caused by the contact between the toner particles and the carrier particles or between the carrier particles due to the stirring in the developing device.
The fine particles of the removed carrier particles together with the toner particles form an unfixed image and adhere to the surface of the fixing roller. Fine powder adhering to the fixing roller slips through a cleaning mechanism such as a cleaning roller or a cleaning pad, and accumulates in a release agent uniforming unit and a release agent amount regulating unit.
The fixing roller was damaged, resulting in a short life of the fixing roller.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus having high image quality, low running cost and long life.

[0014]

According to the present invention, an electrostatic latent image corresponding to an image information signal is formed on an image carrier, and the electrostatic latent image is formed by a two-component developer having toner particles and carrier particles. Image forming means for forming an unfixed image by developing using the same, and transferring the unfixed image to a transfer material; and fixing and fixing the unfixed image by nipping and conveying the transfer material by a fixing rotator and a pressing rotator. In the image forming apparatus having a fixing unit, the carrier particles are a magnetic resin carrier having a binder resin, a magnetic metal oxide, and a non-magnetic metal oxide generated by a polymerization method, and the fixing rotator and the pressurizing unit. An image forming apparatus is provided in which at least one surface material of the rotator includes silicone rubber or fluorine rubber.

[0015]

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

(Embodiment 1) FIG. 2 is a sectional view showing a schematic configuration of a digital four-color full-color image forming apparatus as an example of an image forming apparatus according to the present invention.

The image forming apparatus shown in FIG. 1 includes a lower digital color image printer unit (hereinafter simply referred to as "printer unit") I and the above digital color image reader unit (hereinafter simply referred to as "reader unit") II. Equipped, for example,
An image is formed on the recording material P by the printer unit I based on the image of the document D read by the reader unit II.

Hereinafter, the configuration of the printer unit I and the configuration of the reader unit II will be briefly described.

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, the primary charger (charging unit) 2, the exposure unit 3, the developing unit (developing unit) 4, the transfer unit 5, the cleaning unit 6, the pre-exposure lamp 7, etc. Is arranged. Below the transfer device 5, that is, in the lower half of the printer unit I, a paper feed / conveyance unit 8 for the recording material P is disposed, and further above the transfer device 5, a separating unit 9 is provided, and a downstream side of the separating unit 9 is provided. A fixing device 10 and a paper discharge unit 11 are disposed (on the downstream side in the transport direction of the recording material P).

The photosensitive drum 1 has a base 1a on an aluminum drum and an OPC (organic optical semiconductor) photosensitive member 1b covering the back side thereof, and is driven in a predetermined direction in an arrow R1 direction by driving means (not shown). It is configured to be driven to rotate at the process speed (peripheral speed). The photosensitive drum 1 will be described later in detail.

The primary charger 2 includes a shield 2a having an opening at a portion facing the photosensitive drum 1, and a discharge wire 2 disposed inside the shield 2a in parallel with the generatrix of the photosensitive drum 1.
b 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 supply (not shown), so that the surface of the photosensitive drum 1 is uniformly charged to a predetermined polarity and a predetermined potential.

The exposure means 3 includes a laser output section (not shown) for emitting a laser beam based on an image signal from a reader section II described later, and a polygon mirror 3a for reflecting the laser beam.
, A lens 3b, and a mirror 3c. Exposure means 3
The laser beam irradiates the surface of the photosensitive drum 1 with the laser beam, thereby exposing the photosensitive drum 1 and removing an electric charge of an exposed portion 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 based on the image of the original, and the electrostatic latent image corresponding to each color is separated. Images are sequentially formed.

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, each color of yellow, cyan, magenta, and black based on resin. Toner (developer)
Are provided with developing devices 4Y, 4C, 4M and 4Bk. Each of the developing units 4Y, 4C, 4M, and 4Bk has a developing sleeve 4a for attaching 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. The developing unit is alternatively arranged at a developing position close to the surface of the photosensitive drum 1 by the eccentric cam 4b, and the toner is attached to the electrostatic latent image via the developing sleeve 4a, and a toner image (visible image) Image). The three color developing units other than the developing unit used for development are retracted from the developing position.

The transfer device 5 includes a transfer drum (recording material carrier) 5a having a recording material P on its surface, a transfer charger 5b for transferring the toner image on the photosensitive drum 1 to the recording material P, and a recording material P.
Charger 5c for attracting the toner to the transfer drum 5a, a suction roller 5d opposed thereto, an inner charger 5e, and an outer charger 5f, and the transfer is rotatably driven in the direction of arrow R5. A recording material supporting sheet 5g made of a dielectric is integrally stretched in a cylindrical shape in a peripheral opening area of the drum 5a. As the recording material supporting sheet 5g, a dielectric sheet such as a polycarbonate film is used. 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 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 disposed adjacent to the upstream side of the primary charger 2 and removes unnecessary charges on the surface of the photosensitive drum 1 cleaned by the cleaner 6.

The paper feed unit 8 is provided with recording materials P of different sizes.
Paper feed cassette 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 transport rollers, a registration roller 8c, and the like, and a recording material of a predetermined size. P is supplied to the transfer drum 5a.

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

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

The paper discharge unit 11 includes a conveyance path switching guide 11 a and a discharge roller 11 disposed downstream of the fixing device 10.
b, a paper discharge tray 11c and the like. Further, below the conveyance path switching guide 11a, a conveyance vertical path 11d, a reversing path 11e, a stacking member 11f, an intermediate tray 11g, and a conveyance roller for performing image formation on both surfaces of one recording material P. 11h, 11i, a reversing roller 11j and the like are arranged.

Between the primary charger 2 and the developing device 4 around the photosensitive drum 1, there is provided a potential sensor S1 for detecting the charged potential on the surface of the photosensitive drum, and between the developing device 4 and the transfer drum 5a. Is provided with a density sensor S2 for detecting the density of the toner image on the photosensitive drum 1.

Next, the reader section II will be described.
The reader unit II, which is disposed above the printer unit I, has a platen glass 12a on which a document D is placed.
Exposure lamp 12b for exposing and scanning the image surface, a plurality of mirrors 12c for further reflecting light reflected from document D, lens 12d for condensing the reflected light, and a color separation image signal based on the light from lens 12d. It has a full color sensor 12e to be formed. The color-separated image signal is processed by a video processing unit (not shown) through an amplifier circuit (not shown), and is sent to the above-described printer unit I.

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

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

In the printer section I, the photosensitive drum 1 has an arrow R
It is driven to rotate in one direction, and the surface is uniformly charged by the primary charger 2. A laser beam is emitted from a laser output unit of the exposure unit 3 based on the image signal sent from the reader unit II, and the charged photosensitive drum 1 surface is exposed by a light image E via a polygon mirror 3a and the like. I do. The exposed portion of the surface of the photosensitive drum 1 has its charge removed, whereby an electrostatic 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 and 4Bk are retracted from the developing position. The electrostatic latent image on the photosensitive drum 1 has yellow toner attached thereto by the developing device 4Y and is visualized to be a toner image. The yellow toner image on the photosensitive drum 1 is transferred to the recording material P carried on the transfer drum 5a. The recording material P is supplied to the transfer drum 5a at a predetermined timing from a predetermined paper feeding cassette 8a having a size suitable for a document image via a paper feeding roller 8b, a conveying roller, a registration roller 8c, and the like. Things. The recording material P thus supplied is:
An arrow R is drawn so as to be wound around the surface of the transfer drum 5a.
5 and the photosensitive drum 1 is rotated by the transfer charger 5b.
The upper yellow toner image is transferred.

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

The processes from the reading of the original image by the reader unit II, the transfer of the toner image carried on the recording material P on the transfer drum 5a, the cleaning of the photosensitive drum 1, and the elimination of electricity are described above. Other colors, namely cyan,
The same applies to magenta and black, and the toner images of four colors are transferred onto the recording material P on the transfer drum 5a so as to overlap.

Recording material P to which four color toner images have been transferred
Is separated from the transfer drum 5a by a separation charger 9a, a separation claw 9b, and the like, and is conveyed to the fixing device 10 with an unfixed toner image carried on the surface. The recording material P is a fixing device 1
The toner image on the surface is melted and fixed by the heating and pressing by the fixing roller 10a and the pressing roller 10b. The recording material P after the fixing is discharged onto a discharge tray 11c by a discharge roller 11b. When an image is formed on both sides of the recording material P, the fixing device 10 immediately drives the conveyance path switching guide 11a on the discharged recording material P,
After being once guided to the reversing path 11e via the transport vertical path 11d, the sheet is retreated in a direction opposite to the direction in which the sheet is fed by the reverse rotation of the reversing roller 11j, with the rear end leading, and 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 discharged onto the discharge tray 11c.

On the transfer drum 5a after the separation of the recording material P, the recording material supporting sheet 5g is used in order to prevent scattering of powder on the recording material supporting sheet 5g, adhesion of oil on the recording material P, and the like. Fur brush 1 facing each other through
Cleaning is performed by 3a and the backup brush 13b, and by the oil removing roller 14a and the backup brush 14b. Such cleaning is performed before or after image formation, and is performed as needed when a jam (paper jam) occurs.

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

In FIG. 1, a fixing roller 10a which comes into contact with a toner image is composed of a 2 mm thick HTV (high temperature vulcanization type) silicone rubber layer 32 on an aluminum cored bar 31 and a specific additional type silicone rubber layer on the outside thereof. 33, diameter 6
It is formed at 0 mm.

On the other hand, the pressure roller 10b is provided with an HTV having a thickness of 2 mm and an additional silicone rubber layer 35 having a thickness of 60 mm on an aluminum cored bar 34 having a diameter of 60 mm.
Is formed.

The above-mentioned addition type silicone rubber is an LTV (low-temperature vulcanization type) which is familiar with the silicone oil as a release agent.
Alternatively, it is preferable to use an RTV (room temperature vulcanization type) silicone rubber.

The fixing roller 10a is provided with a heater 36, which is a heating means, in the metal core 31, and the pressure roller 10b is provided with a heater 37 in the metal core 34. Heating from both sides. The temperature of the pressure roller 10b is detected by a thermistor 38 in contact with the pressure roller 10b, and the halogen heaters 36 and 37 are controlled by the control device 39 based on the detected temperature, and the fixing roller 10a and the pressure roller 10b Are controlled so as to maintain a constant temperature of 170 ° C. The fixing roller 10a and the pressure roller 10b are
It is pressurized at a total pressure of about 50 kg by a pressurizing mechanism (not shown).

Further, an oil application device 100 as a release agent application device, a cleaning device 40, and a cleaning blade 50 for removing oil and dirt from the pressure roller 10b are provided respectively.

The oil applicator 100 uses an oil supply pump (not shown) to supply oil to the oil drip pipe 10.
, And a silicone oil therefrom. An oil leveling pad 102 and a regulating blade 1 serving as a release agent equalizing member.
03, the silicone oil is leveled and uniformly applied on the fixing roller 10a. Excess oil passes over the regulating blade 103, is collected in the oil pan 104, and is reused.

The cleaning device 40 includes a web 46 contacted with the fixing roller 10a by the abutting roller 45.
Cleaning the surface of the fixing roller 10a.

In the above-described fixing device 10, the recording material P carrying the unfixed toner image on its surface is nipped and conveyed by a fixing nip between the fixing roller 10a and the pressure roller 10b. The toner is fixed under pressure. At this time, the toner adhered to the fixing roller 10a and the pressure roller 10b is removed by the cleaning device 40 and the cleaning blade 50, respectively.

Next, the development carrier, which is a feature of the present invention, will be described.

The carrier particles used in the present invention are spherical polymerization carriers. The production method is as follows. In this embodiment, a binder resin, a magnetic metal oxide, a non-magnetic metal oxide, and the like are added to a monomer of the polymerization method. The monomer composition was suspended in an aqueous medium and polymerized to obtain spherical carrier particles (the production method is not limited to the above method, and may be produced by an emulsion polymerization method or the like. Other additives may be included). The shape factor of the spherical polymerization carrier obtained by this production method is such that SF-1 is 100 to 15
0 and SF-2 are 100 to 150. This SF-1,
SF-2 is Hitachi FE-SEM (S-800)
, 100 samples of toner are randomly sampled, and the image information is introduced into an image analyzer (Lusex3) manufactured by Nicole via an interface, analyzed, and the value obtained by the following equation is used in the present invention. Is the shape factor SF-
1, SF-2.

[0051]

(Equation 1) (Where AREA is the toner projection area, MXLNG is the absolute maximum length, and PERIME is the circumference).

The above SF-1 indicates a degree of sphere, and when it is larger, the toner gradually changes from sphere to irregular toner. SF-2
Indicates the degree of unevenness, and if it is larger, the unevenness of the surface area becomes remarkable.

With respect to the shape factor of the spherical polymerization carrier,
As for the shape factor of the conventional pulverized carrier, SF-1 is 180 to
Since 220 and SF-2 are 180 to 200, it is understood that the shape of the carrier particles of the spherical polymerization carrier is closer to a perfect circle than the conventional pulverized carrier. The spherical polymerized carrier has a smaller change rate of the shape factor of the carrier particles due to the deterioration of the agent than the conventional pulverized carrier. For example, the change in the shape factor due to the agent stirring and the agent compression that occurs when the developing device is operated for 5 hours. In the pulverized carrier, SF-1 is 120
~ 150 and SF-2 are close to spherical with 120-140, whereas the spherical polymerization carrier has SF-1 of 100 ~ 13.
5. The shape of SF-2 was 100 to 140, and there was almost no shape change. This is because the crushed carrier has toner particles and carrier particles, or the uneven surface layer is scraped off by the friction caused by the contact between the carrier particles, and the crushed carrier approaches a spherical shape. This indicates that the shape change is small because there are few factors that change the shape.

In the above-described embodiment, as a result of performing full-color continuous paper passage durability, no flaw was confirmed on the surface of the fixing roller and the pressure roller even after 100,000 sheets were passed. In addition,
As a comparative example, in the above-described embodiment, similar full-color continuous paper passing durability was performed using a conventional pulverized carrier. As a result, about 60,000 sheets were found to have flaws on the fixing roller.

In the present embodiment, silicone rubber is used for the fixing roller and the pressure roller, but a roller made of fluorine rubber may be used. In this case, as the release agent, it is preferable to use an amino-modified silicone oil that is familiar with fluororubber.

(Embodiment 2) Hereinafter, Embodiment 2 of the present invention will be described with reference to FIG.

The oil application mechanism 100 includes an oil pan 10
4 is moved toward oil application roller 106 by pumping roller 105 to apply silicone oil.
In step 6, silicone oil is applied to the surface of the fixing roller 10a. The amount of silicone oil applied to the fixing roller 10a is
It is regulated by the regulating blade 103.

Other configurations are the same as those in the first embodiment, and as a result of performing full-color continuous paper passing durability,
No flaw was observed on the surface of the fixing roller and the pressure roller even after passing 120,000 sheets. In addition, as a comparative example, the present Example 2
The same evaluation was performed using a conventional pulverized carrier, and as a result, flaws were confirmed on the surface of the fixing roller on about 70,000 sheets.

[0059]

As described above, according to the present invention,
Binder resin produced by the polymerization method, a magnetic resin carrier having a magnetic metal oxide and a non-magnetic metal oxide, and a silicone rubber or a fluorine rubber as a surface material of at least one of the fixing rotating body and the pressing rotating body. By using this, it is possible to provide an image forming apparatus with high image quality, low running cost, and long life.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a developing device for general two-component magnetic brush development.

FIG. 2 is a cross-sectional view of the image forming apparatus according to the embodiment of the present invention.

FIG. 3 is a sectional view of the fixing device according to the first embodiment of the present invention.

FIG. 4 is a sectional view of a fixing device according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List I Digital color image printer unit II Digital color image reader unit 1 Photosensitive drum 2 Primary charger 3 Exposure means 4 Developing device 5 Transfer device 6 Cleaning device 7 Pre-exposure lamp 8 Feeding / conveying unit 9 Separating means 10 Fixing device 10a Fixing roller 10b Pressure roller 11 Paper discharge unit 44 Developing container 52 Developer 54 Developing sleeve 55 Magnet roller 56 Restriction blade 58, 59 Stirring screw 61 Toner storage chamber 100 Oil application device 101 Oil dropping pipe 102 Oil leveling felt oil 103 Restriction blade 104 Oil Pan 105 Oil pump roller 106 Oil application roller

Claims (3)

[Claims] An unfixed image is formed by forming an electrostatic latent image corresponding to an image information signal on an image carrier and developing the electrostatic latent image using a two-component developer having toner particles and carrier particles. And an image forming device that forms the image and transfers the unfixed image to a transfer material, and a fixing device that fixes the unfixed image by nipping and conveying the transfer material by a fixing rotator and a pressing rotator. The carrier particles are a magnetic resin carrier having a binder resin, a magnetic metal oxide and a non-magnetic metal oxide formed by a polymerization method, and a surface material of at least one of the fixing rotating body and the pressing rotating body. An image forming apparatus comprising silicone rubber or fluorine rubber. 2. The image forming apparatus according to claim 1, wherein the shape factor SF-1 of the carrier particles ranges from 100 to 150, and the shape factor SF-2 ranges from 100 to 150. 3. The fixing unit includes: a unit that supplies a release agent to the surface of the fixing roller; a release agent uniformizing unit that equalizes the release agent; and a release agent amount that regulates the amount of the release agent. The image forming apparatus according to claim 1, further comprising a regulating unit.