JP3327111B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an intermediate transfer means of an image forming apparatus using electrophotography.

[0002]

2. Description of the Related Art Before transferring a toner image formed on a photoreceptor to a recording medium, the image is transferred onto an intermediate transfer means, and the toner image is transferred from the intermediate transfer means onto the recording medium to form an image. The forming method is adopted in a color image forming apparatus such as a color copying machine because a multicolor image can be easily formed.

In the above-mentioned intermediate transfer member system, various characteristics are required for an intermediate transfer means for holding a toner image in an intermediate manner. However, if an elastic layer is provided in the intermediate transfer means, a developer is provided at a nip portion between the photosensitive member and the developer. This reduces damage to the photoreceptor that occurs when the carrier is caught, and is effective in extending the life of the photoreceptor.

Another advantage of providing an elastic layer is disclosed in
As described in Japanese Patent Application Laid-Open No. 1-198773, there is also an effect that the nip at the transfer point between the photosensitive member and the intermediate transfer means is stably secured. Also, the provision of an elastic layer on the surface layer of the intermediate transfer means causes the lowermost layer of the toner to adhere to the surface of the intermediate transfer means, thereby lowering the transfer efficiency of the toner.
As disclosed in Japanese Patent Application Laid-Open No. 7-234592, it has been proposed to fix fine particles having a particle diameter equal to or less than half of the toner particle diameter on the surface of the intermediate transfer means.

[0005]

As in the prior art described above, it is effective to provide an elastic layer on the intermediate transfer means, and to fix fine particles on the surface of the intermediate transfer means improves the transfer efficiency. It is effective for

However, since the fine particles have a small absolute mass, they tend to float in the air, and it is extremely difficult to fix them on the surface of the elastic body. This point is not described.

In order to fix the fine particles only partially on the surface of the elastic body, it is possible to press the fine particles against the surface of the intermediate transfer member. However, it is necessary to fix the fine particles uniformly on the entire surface of the intermediate transfer member. Is extremely difficult.

If the fixation of the fine particles is not uniform, the transfer efficiency of the toner becomes uneven throughout the entire image, resulting in transfer unevenness. Therefore, problems such as various image defects such as unevenness of line thickness occur.

[0009]

SUMMARY OF THE INVENTION The present invention has been devised in order to solve the above-mentioned problems, and is intended to provide a uniform surface having good elasticity at the same time as the intermediate transfer means and good releasability from the toner. The intermediate transfer means has an elastic layer, and on the surface of the intermediate transfer means, fine particles having a particle diameter of 1/10 or less of the toner particle diameter and a particle diameter equal to or smaller than the toner particle diameter and larger than the fine particles by fixing at least two kinds of particle size of different microparticles frictional contact with the particles, is
Further, among the two or more types of fine particles having different particle diameters,
At least one type is particles based on silica (SiO ₂ ).
And the silica substituted the particle surface with a hydrophobic functional group.
This is a hydrophobic silica .

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic sectional view of an image forming apparatus using the present invention, and the structure of the apparatus will be described with reference to the drawings.

A controller (not shown) for controlling the printer is provided at the back of the main body. The controller contains an image signal processing unit and a print command control unit.

A belt-shaped photoreceptor 1 stretched by three rotatable shafts is provided at a central portion on the right side of the main body.

The photosensitive belt 1 has a photosensitive layer (for example, OPC) on the surface, and a conductive layer (for example, aluminum) under the photosensitive layer.
And has a two-layer structure.

The photoreceptor belt 1 travels in the X direction. In the vicinity of the photoreceptor belt 1, the charger 2, the exposure means 3, the developing means 4a, 4b,
4c, 4d, an intermediate transfer drum 5, an erase lamp 6, and a photoconductor cleaner 7 are provided.

The intermediate transfer drum 5 includes a cleaner 8.
And a pre-transfer charger 9.

The charger 2 is a corotron charger, and charges a photosensitive member by discharging a corotron wire.

The exposure means 3 comprises a laser diode, a polygon mirror, an fθ lens and a case containing them.

The four developing devices of developing means 4a, 4b, 4c and 4d are of the same type, but contain toners of different colors, for example, yellow, magenta, cyan and black, respectively. develop. Each of them operates independently.

The intermediate transfer drum 5 has a diameter of 80 to 150 mm.
Cylindrical, conductive cylindrical substrate (eg aluminum drum)
And a surface layer covering the same (details will be described later).

The conductive cylindrical body is connected to the ground. The intermediate transfer drum 5 is pressed against the photoreceptor belt 1 with an appropriate pressure, contacts the nip with a nip width of 5 to 20 mm, and the toner image formed on the photoreceptor belt 1 The image is transferred onto the intermediate transfer drum 5 by the voltage applied to the one conductive layer.

The photosensitive belt 1 and the intermediate transfer drum 5 may both be driven, or one may be driven by the other.

The erase lamp 6 removes the residual potential on the photoreceptor belt 1 after transfer by light irradiation.

The photoconductor cleaner 7 removes residual toner remaining on the photoconductor belt 1 after the transfer.

Similarly, the cleaner 8 removes the toner remaining on the intermediate transfer drum 5 after the transfer of the recording medium.

The cleaner 8 is retracted upward while a toner image is being formed on the intermediate transfer drum 5.

The pre-transfer charger 9 has a function of making the potential of the surface of the toner on the intermediate transfer drum 5 constant and improving the transfer.

Below the photosensitive belt 1, a paper cassette 1 is provided.
1 is provided. Above the paper cassette 11, there is a pickup roller 12, whereby the recording medium 10 is pulled out of the paper cassette 11, and is discharged through a registration roller 13, a transfer roller 14, a static eliminator 15, and a fixing device 16.

The registration roller 13 is for aligning the leading edge of the recording medium 10.

The transfer roller 14 is for transferring the toner image formed on the intermediate transfer drum 5 onto the recording medium 10 and has a metal shaft and an appropriate resistance value (1 k to 10 GΩ).
Of the elastic layer.

An appropriate voltage for transfer is applied to the metal shaft to transfer a toner image. Also, the transfer roller 1
Reference numeral 4 indicates that the toner is not in contact with the intermediate transfer drum 5 while the toner image is being formed on the intermediate transfer drum 5.

The static eliminator 15 neutralizes the recording medium 10, and the fixing unit 16 fixes the toner on the recording medium 10.

Next, the surface layer of the intermediate transfer drum 5 of the present invention will be described in detail.

FIG. 2 is a schematic structural view of the surface of the intermediate transfer drum 5 used in this embodiment.
The elastic layer 5b is formed on the elastic layer 5a, and fine particles 5c and 5d are fixed on the surface of the elastic layer 5b.

Thus, by covering the surface of the elastic layer with the fine particles, the adhesiveness of the elastic layer is reduced.

This is because the adhesive force of the toner is suppressed by the above-mentioned surface structure so that the adhesive property is lost when sand is adhered to the surface of the adhesive tape.

Further, as the surface characteristics of the fine particles, when particles having a small surface energy such as hydrophobic silica are used, the adhesion to the toner is further reduced, so that a further effect can be obtained.

Next, the characteristics of each layer will be described in detail. The intermediate transfer drum base material 5a is a cylindrical base tube made of metal (such as aluminum).

The elastic layer 5b is formed to have a thickness of about 0.1 to 3 mm so that the carrier of the developer is hardly damaged even when the carrier of the developer is caught in the nip between the photosensitive belt 1 and the intermediate transfer drum 5. is there.

As the material, polyurethane rubber, chloroprene rubber, nitrile rubber, epichlorohydrin rubber, silicone rubber, acrylic rubber, fluorine rubber and the like are used. The reason why a very wide variety of materials can be selected is that the adhesion of the fine particles 5c and 5d to the surface makes the surface less sticky.

Incidentally, the elastic layer 5b does not necessarily have to be formed as a single layer. For example, polyurethane rubber has a characteristic that it is deteriorated under the influence of ozone generated from the charger 2 and the like.

For this reason, when urethane rubber is used as the material of the elastic layer 5b, in order to prevent this deterioration, the elastic layer 5b has a two-layer structure, and the surface is made of a layer of another material (for example, fluorine rubber or fluorine resin). It is better to adopt a structure of covering with a dispersed fluororubber).

FIG. 3 is a schematic sectional view of the surface of the intermediate transfer drum 5 in which an intermediate layer 5e covering the surface is added to the elastic layer 5b. The layer constituting the upper layer of the elastic layer 5b as in this example is preferably made of a material having elasticity.

In order to control the resistance value of the intermediate transfer drum 5, a layer for adjusting the resistance inside the elastic layer 5b (for example, a layer having a high resistance, such as a blocking layer used as an underlayer of a photoreceptor, For a medium resistance material such as PET, a rubber material such as the above-described fluorine rubber or a semiconductive plastic may be used, and a material may be selected according to the resistance value of the elastic layer 5b and other layers. .

FIG. 4 shows an insulating layer 5 under the elastic layer 5b.
3 shows a schematic cross-sectional view of the surface of the intermediate transfer drum 5 having f.

In this case, the structure in which the resistance layer is formed in the lowermost layer of the elastic layer 5b does not necessarily have to have elasticity. However, when the resistance layer is formed in the middle and upper layers of the elastic layer 5b, elasticity is not required. I need.

The fine particles 5c have an average particle diameter of 10
Use one that is less than 1 /.

In this embodiment, the toner having an average particle diameter of 7 μm is used. However, the present invention is not limited to this.
20 μm toner may be used.

The material of the fine particles 5c is silica (Si
O ₂ ), silicone resin, polyester resin, acrylic resin, fluororesin, etc., which do not adhere to the toner, are used as the base material. Hydrophobic silica substituted with a functional group having low adhesion to toner is suitable.

The particles 5d which are equal to or smaller than the particle diameter of the toner and larger than the fine particles 5c are formed by the above-mentioned silica.
(SiO ₂ ), silicone resin, polyester resin, acrylic resin, fluororesin, and other materials that do not stick to the toner are used as the base material. Among these base materials, the silicone resin has low surface energy and therefore has low adhesion to the toner. Low and preferred.

The shape of the large particles 5d is desirably spherical. By fixing at least one or more of the fine particles made of these materials on the surface of the intermediate transfer drum 5, the adhesion to the toner can be reduced. By using the particles, it is possible to increase the pressure contact force for fixing these fine particles.

Specifically, as shown in FIG.
When pressure is applied to the microparticles 5c and 5d in step 7, the stress applied to the micropart can be concentrated by the presence of the large particles 5d, and the fixing force of the microparticles 5c also increases.

Further, by making the shape of the large particles 5d spherical, and performing pressure contact while sliding, the large particles 5d serve as rollers, so that the surface of the intermediate transfer means is smooth and smooth. Without damaging the fine particles 5c,
Good fixation can be performed on the entire surface of 5d.

These two types of fine particles 5 having different sizes
The mixing ratio of c and 5d is such that the uniform and dense fixation of the fine particles 5c improves the releasability of the toner.
It is desirable to increase the blending amount of the smaller particles 5c than the larger particles 5d. Preferably, the blending amount of the large particles 5d is 3 to 50 wt.% With respect to the total amount of the fine particles 5c and the large particles 5d.

Here, a method of fixing the fine particles 5c and 5d on the surface of the intermediate transfer drum 5 will be briefly described.

A friction member is applied to the surface of the intermediate transfer drum 5,
The microparticles 5c and 5d are mixed in the contact portion and friction is caused by giving a speed difference, and the microparticles 5c and 5d are fixed to the surface of the intermediate transfer drum 5 by frictional contact.

At this time, if particles 5d having a larger particle size than the fine particles 5c are mixed and brought into frictional contact, fixation can be performed in a relatively short time.

The fine particles 5c and 5d can be dispersed in a solvent. Examples of the solvent include alcohols (for example, ethyl alcohol and isopropyl alcohol), ethers (for example, dimethyl ether and diethyl ether), and the like. Ketones (eg, acetone, 2-butanone, etc.), hydrocarbons (eg, hexane, heptane,
Organic solvents such as cyclohexane), aromatic solvents (eg, toluene, xylene, etc.), or mixed solvents using at least one of them, or aqueous solvents to which a dispersant or emulsifier is added, etc. After the fine particles 5c and 5d are dispersed in the solvent, the surface of the transfer drum 5 is applied by spraying or the like, and then fixed by frictional contact.

The fine particles 5c, 5 thus fixed
d adheres relatively firmly to the intermediate transfer drum 5,
It is hardly removed by wiping with a solvent such as alcohol, and the intermediate transfer drum 5 can be cleaned and reused.

In the above example, the intermediate transfer means is a drum-shaped apparatus. However, even if the intermediate transfer means is a belt-shaped apparatus, fine particles can be fixed on the surface as in the above example. It is clear that good characteristics can be obtained with.

The method of fixing the fine particles on the surface as described above was effective not only for the intermediate transfer drum 5 but also when applied to a member which comes into contact with the toner and requires elasticity.

For example, when the surface of the transfer roller or the transfer belt was subjected to the surface treatment as in this embodiment, the toner stain on the roller and the belt was reduced, and the cleaning of those members became easy.

Further, by fixing the heat-stable fine particles to the surface of the fixing roller, there is also an effect of reducing the offset.

Such an application is an example applicable to not only the intermediate transfer type image forming apparatus of the present embodiment but also other type image forming apparatuses.

The operation of the electrophotographic apparatus configured as described above will be described below.

First, when a print command is input from the computer to the controller, the photosensitive belt 1 starts moving, and is exposed from the exposure means 3 onto the photosensitive belt 1 charged by the charger 2 to form a latent image. Is done. This latent image is first developed by the developing means 4a.

The developed toner image is transferred onto the intermediate transfer drum 5. Next, the photoreceptor belt 1 is charged and exposed again, and is then developed by the developing means 4b.

Then, the developed toner image is transferred onto the intermediate transfer drum 5 so as to overlap the previous image.

This process is thereafter repeated with the developing means 4c and 4d to form a plurality of color toner images on the intermediate transfer drum 5. The toner image formed on the intermediate transfer drum 5 is adjusted in potential by the pre-transfer charger 9, and is transferred at once by the transfer roller 14 to the recording medium 10 pulled out of the paper cassette 11 by the pickup roller 12.

Then, the recording medium 10 is neutralized and peeled by the neutralizer 15 and sent to the fixing device 16 to be fixed.

At this time, when the intermediate transfer drum 5 having the fine particles 5c and 5d fixed on the surface described in detail above was used, the surface of the intermediate transfer drum 5 was elastic. The photoreceptor belt 1 is not damaged even if foreign matter such as a carrier is caught, and the life of the photoreceptor belt 1 has been deteriorated after about 1,000 sheets have passed. became.

Further, since the adhesive force between the surface of the intermediate transfer drum 5 and the toner is reduced, the transfer efficiency from the intermediate transfer drum 5 to the recording medium 10 is increased by up to 5%, which has a great effect on improving the image density. .

Further, the voids in the characters and thin lines were reduced to a level almost invisible to the naked eye, greatly contributing to the improvement of the image quality. Further, the amount of toner remaining on the intermediate transfer drum 5 after transferring the toner to the recording medium 10 is reduced by the transfer efficiency, and the cleaning efficiency by the cleaner 8 is improved. Then, the stain on the next image was almost eliminated.

As described above, by using the present invention, an image forming apparatus having high image quality and low maintenance can be realized.

[0075]

According to the present invention, the intermediate transfer means is provided with an elastic layer, and the surface of the intermediate transfer means has fine particles having a particle size of 1/10 or less of the toner particle size, By fixing particles that are equal to or smaller than the fine particles, the deterioration of the photoconductor due to the engagement of the developer carrier into the nip of the photoconductor and the intermediate transfer unit is prevented, and the toner is transferred to the intermediate transfer unit. There is no sticking.

Further, the fixation of these fine particles to the intermediate transfer means becomes uniform and dense.

As a result, the life of the photosensitive member is prolonged, high-efficiency transfer of the toner to the recording medium is realized, and the uniformity of the image is high. An image forming apparatus in which a high-quality image was not formed was obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a surface structure of an intermediate transfer drum.

FIG. 3 is a diagram illustrating another embodiment of the surface structure of the intermediate transfer drum.

FIG. 4 is a view for explaining another embodiment of the surface structure of the intermediate transfer drum.

FIG. 5 is a diagram illustrating a method for fixing fine particles on the surface of an intermediate transfer drum.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photoreceptor belt, 2 ... Charging device, 3 ... Exposure means, 4a,
4b, 4c, 4d: developing means, 5: intermediate transfer drum, 5
a: Intermediate transfer drum base material, 5b: Elastic layer, 5c, 5d ...
Fine particles, 5e: intermediate layer, 5f: insulating layer, 6: erase lamp, 7: photoreceptor cleaner, 8: cleaner, 9: pre-transfer charger, 10: recording medium, 11: paper cassette, 12
... pickup roller, 13 ... registration roller, 14 ...
Transfer roller, 15: static eliminator, 16: fixing device, 17: pressing member.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masashi Yamamoto 7-1-1, Omikacho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Tetsuo Ishikawa 1-1-1, Higashitaga-cho, Hitachi City, Ibaraki Prefecture No. 1 Inside the Taga Headquarters, Hitachi, Ltd.Electrical Equipment Division (72) Inventor Hiroyuki Onodera 1-1-1, Higashitagacho, Hitachi City, Ibaraki Prefecture Inside the Taga Headquarters, Hitachi, Ltd.Electrical Equipment Division (72) Inventor Masahiro Nakano 1-1-1, Higashitaga-cho, Hitachi City, Ibaraki Pref. Hitachi, Ltd. Electrical Appliances Division, Taga Headquarters (56) References JP-A-7-234592 (JP, A) (58) Fields surveyed (Int. ⁷ , DB name) G03G 15/16

Claims (4)

(57) [Claims] 1. A copy rolling the toner image on the photosensitive member, said transfer photographed
Intermediate transfer means of an image forming apparatus for transferring an obtained toner image to a recording medium to form an image, wherein the intermediate transfer means has an elastic layer and a particle size of the toner particle size on the surface of the intermediate transfer means. At least two kinds of fine particles having different particle diameters, that is, fine particles of 1/10 or less and particles having a particle size equal to or smaller than the toner particle size and larger than the fine particles, are fixed by friction contact. And two or more types of fine particles having different particle sizes.
At least one of them is based on silica (SiO ₂ )
Particles, and the silica coats the particle surface with hydrophobic functional groups.
Intermediate transfer characterized by substituted hydrophobic silica
Method of manufacturing the means. 2. A method for transferring a toner image on a photoreceptor, and
Transfer the transferred toner image to a recording medium to form an image.
An intermediate transfer unit of the image forming apparatus, wherein the intermediate transfer unit has an elastic layer and the intermediate transfer unit.
The particle size on the surface of the copying means is 1/10 or less of the toner particle size
Fine particles and the particle size is equal to or smaller than the toner particle size
And at least two kinds of particles larger than the fine particles
Small particles of different diameters are fixed by friction contact
Further , among the two or more types of fine particles having different particle sizes, at least the fine particle having the larger particle size is a particle based on a silicone resin .
Manufacturing method . 3. The method according to claim 1, further comprising the step of transferring the toner image on the photosensitive member.
Transfer the transferred toner image to a recording medium to form an image.
An intermediate transfer unit of the image forming apparatus, wherein the intermediate transfer unit has an elastic layer and the intermediate transfer unit.
The particle size on the surface of the copying means is 1/10 or less of the toner particle size
Fine particles and the particle size is equal to or smaller than the toner particle size
And at least two kinds of particles larger than the fine particles
Small particles of different diameters are fixed by friction contact
Was further out of the particle size of two or more kinds of fine particles to be fixed, fine particles of at least towards the particle diameter is large intermediate transfer hand, characterized in that its shape is a shape close to a sphere
Step manufacturing method . 4. An intermediate transfer hand according to claim 1, wherein two or more elastic layers are formed.
Step manufacturing method .