JPH03131883A - Transfer device of image forming device - Google Patents

Abstract

PURPOSE:To prevent an image from running owing to electrostatic charging products, toner from being fused, and the picture quality from deteriorating by forming a transfer means of two-layered constitution and roughening the surface which faces a photosensitive body 1. CONSTITUTION:The transfer roller 12 of two-layered constitution is formed and an elastic layer 22 is formed at the periphery of the mandrel 21; and a polyurethane thermoplastic elastomer layer 24 is formed across an adhesive layer 23 and its surface is roughened. Thus, the surface of the transfer roller 12 is roughened and magnetic toner, paper powder, etc., which stick on the photosensitive body 1 are scraped off, those particulates are gathered in recessed parts in the surface of the transfer roller 12, and magnetite in magnetic toner operates as abrasive grains, so foreign matter on the surface of the photosensitive body 1 is scraped off and cleaning operation by a cleaner 8 is made effective. Consequently, the image run, the fusion of toner, and the deterioration in the picture quality due to the electrostatic charging products are precluded.

Description

Detailed Description of the Invention (1) Purpose of the Invention (Field of Industrial Application) The present invention relates to an image forming apparatus that uses an electrostatic transfer process, such as an electrostatic copying machine and a printer, and particularly to a transfer apparatus thereof. It is.

(Prior art and problems to be solved) An image carrier and a contact type transfer means such as a transfer roller or a transfer belt that is in pressure contact with the image carrier are provided, and a pressure nip between the two is used as a transfer site to transfer paper or the like. At the same time as supplying the transfer material, applying a transfer bias to the transfer means,
Image forming apparatuses have already been proposed in which a toner image previously formed on the surface of an image carrier is transferred to a transfer material by the action of the electric field thus formed.

FIG. 1O is a schematic side view of the main parts of a typical example of such an image forming apparatus.

A cylindrical image carrier (hereinafter referred to as a photoconductor) 1 having an axis perpendicular to the plane of the paper and rotating in the direction of arrow a is connected to a power source 4.
is uniformly charged by a corona charger 3 connected to
An image signal 5 such as an image-modulated laser beam is irradiated onto the charged surface, the potential of that portion is attenuated, and an electrostatic latent image is formed.

Next, when this latent image reaches a developing area where the photoconductor l and the developing device 6 face each other, toner is supplied from the developing device 6 and adheres to the latent image area to form a toner image, and the toner image is formed on the photoconductor l. As the toner image rotates, when this toner image reaches the transfer site formed as a nip between the photoreceptor l and the transfer roller 2 that is in pressure contact with the photoreceptor l, the transfer material P is transferred from the conveyance path 7 in synchronization with the toner image. The toner image on the photoreceptor side is transferred to the transfer material by being conveyed to the transfer site, and at the same time, a transfer bias is applied to the transfer roller 2 connected to the power source 4.

Thereafter, the transfer material P carrying the toner image leaves the transfer site and is conveyed to a fixing site (not shown), and some toner remaining on the photoreceptor 1 without being transferred to the transfer material during transfer is removed by a cleaner 8. The photoreceptor is now ready for the next step.

When transferring with a device that uses such contact-type transfer means, especially when paper, which is often used as a transfer material, is used as a transfer material, fine paper dust may be generated.

Precipitates such as rosin and talc that are deposited from paper adhere strongly to the photoreceptor and cannot be removed even with a cleaning blade, which can cause image blur due to toner fusion and deterioration of image quality due to poor cleaning. . Furthermore, silica, which is finer than the toner and is added to improve the functionality of the toner, may exhibit similar behavior.

In addition, when a corona charger is used, a large amount of ozone is generated, which causes charged products such as NO to adhere to the photoreceptor and form a low resistance layer, resulting in latent images and image disturbances. This is especially noticeable when negatively charging an OPC photoreceptor.

The present invention has been made in order to cope with such a situation, and uses a contact type transfer means that presses against the photoreceptor to remove paper dust and other foreign matter adhering to the photoreceptor or to prevent adhesion to the photoreceptor. It is an object of the present invention to provide a transfer device that can maintain a photoreceptor as clean as possible at all times by weakening the photoreceptor, and can perform stable and good transfer.

(2) Structure of the invention (technical means for solving the problem and its operation) In order to achieve the above object, the present invention provides a transfer method in an image forming apparatus equipped with an image carrier and a transfer means in contact with the image carrier. The transfer device is characterized in that the transfer device has at least two layers, and the surface facing the photoreceptor is formed into a rough surface.

With this configuration, the surface of the photoreceptor is effectively cleaned to prevent image blurring and toner fusion caused by charged products, and it is always stable and good without being affected by environmental changes. transfer can be performed.

(Description of Embodiments) FIG. 1 is a side view showing an outline of an image forming apparatus according to an embodiment of the present invention, in which parts corresponding to the apparatus shown in FIG. Since the basic operations of image formation are not particularly different from those of known devices, a description thereof will be omitted.

In this device, a charging roller I is used as a primary charging means.
3 is used to suppress the generation of ozone, and the photoreceptor 1 is an oPc photoreceptor.

Further, the transfer roller 12 is configured as described below.

As shown in FIG. 2, the transfer roller 12 has a multilayer structure, and around a core metal 21 made of stainless steel or the like,
An elastic layer 22 made of EPDM%CR rubber, NBR, urethane rubber, silicone rubber, fluororubber, etc. is formed, and PvdF, PET thermoplastic elastomer, olefin thermoplastic elastomer, polyurethane thermoplastic elastomer, etc. are formed through the adhesive layer 23. The layer 24 is made of a resin or elastomer selected from a plastic elastomer, a polyethylene elastomer, a polyamide thermoplastic elastomer, a fluorine thermoplastic elastomer, an ethylene-vinyl acetate elastomer, a polyvinyl chloride thermoplastic elastomer, and the like.

The elastic layer 22 surrounding the core metal 21 is made of carbon, ZnO
, Sn○2, titanium compounds, nickel compounds, silicon compounds, and other conductive materials are dispersed to increase the volume resistance to 104.
~101sΩcII+, preferably 104-10'Ω
cm, and the hardness of the transfer roller is 15 cm.
~40° (Asker-〇), preferably 20-30'
shall be used.

A surface layer 24 made of a surface resin or an elastomer is bonded to the elastic layer 22 by an adhesive layer 23, and its volume resistance is determined by changing the molecular structure of the polymer by mixing other polymers to make it conductive. 1014ΩcI1
1, preferably adjusted to about 1010 to 1013 Ωcm.

The hardness can be used in a wide range from 30 to 90" Shore D hardness, but in relation to the thickness range of 50 to 300 μm, the thickness is set to 100 to 200 μm, and the hardness is set to Shore D hardness correspondingly. The length is preferably 35 to 60'.

In the device of the above embodiment, foamed urethane rubber was used as the elastic layer, and the hardness was 25L (Asker 〇), and the volume resistance was adjusted to 104 to 105 Ωcm by dispersing carbon. A thermoplastic elastomer with a hardness of 35 degrees Shore D and a volume resistance of 1011.
~10100 cm and a thickness of 200 um was used as the surface layer.

The reason why polyurethane-based elastomer is used for the surface layer is that it has high abrasion resistance.

In such an apparatus, in the present invention, the polyurethane thermoplastic elastomer of the surface layer is formed into a tube shape by extrusion molding, and the surface of the polyurethane thermoplastic elastomer is
A rough surface in the range of 15 to 30 μm was formed in the illustrated apparatus.

Since the surface of the transfer roller is thus formed with a rough surface, magnetic toner, paper dust, etc. adhering to the photoreceptor 1 tend to be scraped off, and these fine particles are taken into the recesses on the surface of the transfer roller. The magnetite contained in the magnetic toner acts as an abrasive, scraping off the aforementioned foreign matter on the surface of the photoreceptor or weakening its adhesion to the photoreceptor, making the cleaning effect of the cleaner more effective. Therefore, it is possible to perform good cleaning, and it is possible to effectively prevent image deletion and toner fusion even under high temperature conditions.

Experimental examples will be explained below.

In the device shown in Figure 1, the diameter of the photoreceptor is 30L,
The process speed was 50 mm/sec, and the transfer roller had the above-mentioned configuration and had an outer diameter of 16 mm and a length of 220 mm. The pressing force of the roller against the photoreceptor is 50 to 200 g.
The range of r/cm2 is good, but from the viewpoint of transportability of the transfer paper
20~140 gr/c+a''.

With the above specifications, we conducted too many sheet feeding experiments in each environment, and found that the temperature was low and low humidity (15°C, 10%RH: L/L)
There was no problem at all at room temperature (23℃, 60%RH:N/N), but at high temperature (35℃)
, 85% RH: H/H) environment, there was no occurrence of image deletion or toner fusion.

When similar experiments were conducted using non-magnetic toner, H
/ Under Hbt environment, image blurring occurred after about 150 sheets were passed.

This is thought to be because the non-magnetic toner is made only of resin and does not contain hard magnetite, so it lacks abrasive action.

As described above, it has been confirmed that by using the transfer roller and self-control toner configured as described above, good transfer can be performed in any environment.

FIG. 4 shows another embodiment of the transfer roller.

The basic structure of the transfer roller consisting of urethane rubber, adhesive layer, and polyurethane thermoplastic elastomer is the same as that described above, and the illustrated roller has a structure in which abrasives are classified and arranged on its surface layer.

As shown in the figure, an abrasive 40 is dispersed in the surface layer 24, and examples of the abrasive include inorganic materials such as diamond, corundum, etc.
Emery, garnet, silicon carbide, boron nitride, ceria (Ce O□), diatomaceous earth, iron oxide, chromium oxide (III
), the organic material may be any material having a hardness of Shore D hardness of 80° or more and which can be powdered, such as fluororesin and vinyl chloride.

In this embodiment, fluororesin powder was used as the Ce0a organic material as an inorganic material.

First, let us discuss the case of CeO, a distributed system.

The roller itself is made of urethane-adhesive layer, similar to the above-mentioned one.
Made of polyurethane thermoplastic elastomer.
The particle size of Cent dispersed in this surface layer is 5 to 20 μm.

The particle size that can be used is 1 to 40 μm, but if it is too small, it will not have a polishing function, and if it is too large, it will damage the photoreceptor, so it is necessary to select an appropriate particle size.

10 to 30 parts by weight of the above Ce0- (same in the following cases)
, preferably 20 parts, are uniformly dispersed.

Next, the fluororesin powder will be described.

A particle size of 5 to 2
Disperse 0 μm powder PVdF.

In this case as well, the usable particle size is 5 to 50 μm, which was selected for the same reason as above.

The hardness is 90/l in Shore D, and the amount of dispersion is 30 to 60 parts, preferably 40 to 50 parts, and is uniformly dispersed.

All of these dispersed powders are insulating, but the volume resistivity of the polyurethane thermoplastic elastomer that forms the surface layer is adjusted to 101' to 1013 Ωcm, and the surface roughness R2 is 5 to 15 μm, depending on the amount of dispersion.

When testing 10,000 sheets each on these transfer rollers, we found that the cleaning performance was improved by polishing the surface of the photoreceptor, removing adhered foreign matter, and enhancing the polishing action of the magnetic toner incorporated into the surface irregularities. Even under the H/H environment, there was no occurrence of image deletion or toner fusion.

FIG. 5 shows still another embodiment of the transfer roller, which has the same basic structure as the one described above, but is constructed by dispersing magnetic powder on the surface layer of the transfer roller.

Magnetic powders include Fe fine particles obtained by hydrogen reduction of iron oxide (goethite) fine particles, hydrogen reduced products of fine powder coprecipitates obtained from metal salt solutions of Fe, Co, and Ni, metals or alloys in an inert gas. Fine powder obtained by vapor deposition can be used.

In this case, ferrite (γFe0xl) is dispersed in the surface layer. The particle size of the ferrite is 10 to 100 μm, preferably 10 to 20 μm.

By dispersing ferrite on the surface in this way, the En-based toner 5 that adheres to the surface of the photoreceptor when the paper is not passed is removed.
This will cause I to be absorbed.

The tolerance for the surface roughness of the roller varies from 3 to 300 μm, and in this embodiment it was set to 3 to 10 uJ.

The magnetite of the magnetic toner adsorbed on the roller surface acts as an abrasive and polishes the surface of the photoreceptor to make it easier to remove attached foreign matter, improving cleaning performance.

The amount of ferrite to be dispersed was 10 to 40 parts, in this case 20 parts. If there is too little ferrite, the abrasive action is insufficient and the desired effect cannot be obtained, and if there is too much ferrite, the problem arises that the back surface of the transfer material passing through the transfer site is stained.

Since the magnetic force of ferrite is small, it does not interfere with transfer.

The rollers described above are incorporated into the device shown in the first figure.
Although 0,000 sheets were passed, there was no occurrence of image deletion or toner fusion even under the H/H environment.

FIG. 6 shows still another embodiment of the transfer roller.

The elastic layer is formed of urethane rubber, and on top of that, PVdF is wound to a thickness of 50 μm via an adhesive layer, and on top of that, a sheet of woven polyester fiber is wound.
It was impregnated with a molten fluorocarbon thermoplastic elastomer and bonded to the lower layer of PVdF.

The polyester fiber sheet was formed by forming a 20 denier fiber into a thread having a thickness of 10 gm, and knitting this into a sheet. Thickness is 110-100u, preferably 10-5
Approximately 0 μm is suitable.

The volume resistance was adjusted to 1010 to 1014 Ωcm.

The final thickness of the surface layer 60 composed of PVdF, polyester fibers, and fluorine thread thermoplastic elastomer thus constructed is in the range of 70 to 200 μm, and in the case shown, the thickness is 100 μm, and the volume resistivity is 1011 to 101
3 Ωcm, and the surface roughness was 15 to 25 μm.

When the transfer roller configured as described above was incorporated into the apparatus shown in Figure 1 and 10,000 sheets were passed in each environment, no image blurring or toner fusion occurred in all environments including H/H. There wasn't.

It should be noted that the fibers wound on the surface of the roller are not limited to polyester, and may include various other conductive fibers, nonwoven fabrics with appropriately adjusted resistance, etc.
can be used.

Next, an embodiment will be described in which a circumferential speed difference is applied between the photoreceptor and the transfer roller when paper is not passing, causing them to rub against each other, and foreign matter on the photoreceptor is removed by the resulting friction.

The experiment was conducted using the apparatus shown in FIG. 1, and the transfer roller used was one having a structure of urethane rubber, adhesive layer, and PVdF.

The hardness of the urethane rubber is Asker-C254, and the volume resistance is 1.
A material in which carbon was dispersed so as to have a concentration of 0.04 or less was used.

The surface layer PVdF has a thickness of 150 μm and a shore D hardness of 60.
/L, volume resistivity was 10'' to 10'3 Ωcm, and the outer diameter of the roller was 162.

As described above, the diameter of the photoreceptor was 30 mm, the pressure force of the transfer roller against the photoreceptor was 120 to 140 gr/crhl, the length of the transfer roller was 220 mm, and the nip width was 4 mm.

The process speed is based on 50 mm/sec,
When the paper was not passing, the speed was varied by 90-140%.

FIG. 7 shows a timing chart when the peripheral speed difference is 120%.

Using plain paper as the transfer material, Performed under H/H environment The experimental results are shown in the table below.

(Margin below °) As can be seen from the table above, the peripheral speed difference is 101 to 105%.
Even after passing more than 1,000 sheets, no image bleeding or toner fusion occurred.

If the circumferential speed difference is 98% or less, it is not preferable that the foreign matter adhered to the photoreceptor tends to be pressed onto the photoreceptor and firmly adhered to the photoreceptor rather than being removed.

FIG. 8 is a side view of essential parts of an embodiment of the apparatus using a transfer belt as the transfer means.

A transfer belt 82 suspended between a support roller 86 and a drive roller 85 driven by a drive means (not shown) comes into contact with the photoreceptor 1 and runs in the direction of the arrow.

The transfer material P is supplied to the transfer belt 82 from the right side in the figure, and when it reaches the transfer site where the photoreceptor l and the transfer belt 82 are opposed, a voltage is applied to the roller electrode 83 from the power source 84, and the transfer material P is supplied to the transfer belt 82 from the right side in the figure. The toner image formed on the photoreceptor 1 is transferred to the transfer material P.

After transfer, the transfer material is separated from the transfer belt and moved to the fixing area (
(not shown), and the transfer belt is cleaned by a cleaner 88 and prepared for the next process.

Next, the transfer belt of the above device will be explained.

The transfer belt has a structure consisting of a resin layer/adhesive layer/semiconductor layer from the inside.

The resin layer is selected from PET, fluororesin, polyethylene, polyimide, polyamide, polycarbon, polysulfone, etc., with a thickness of 50 to 150 μm, a shore D hardness of 80 imaginary or higher, and a volume resistance of 1O1' to 10I7 Ωcm.

The semiconductor layer is selected from PVdF, PET-based thermoplastic elastomer, polyurethane-based thermoplastic elastomer, polyolefin-based thermoplastic elastomer, fluorine-based thermoplastic elastomer, ethylene-vinyl acetate-based thermoplastic elastomer, polyvinyl chloride-based thermoplastic elastomer, and the like.

Its volume resistance is 10"~10"0cm, thickness 30~1
50 μm, and the hardness is adjusted to a Shore D hardness of 30 to 60.

FIG. 9 describes an embodiment in which abrasives are dispersed in the transfer belt as described above.

The resin layer 91 has a thickness of 100 μm and a volume resistance of 10
A semiconductive layer 9 made of a fluororesin with a Shore D hardness of 90 & 14~101@ΩC11l and arranged via an adhesive layer 92.
3 has a thickness of 50 um and a volume resistance IQ of 11 to 1013 Ω.
cII+ with Shore D hardness of 35 was used.

Further, the surface layer 93 is coated with PVd having a hardness of 80 degrees or more and a particle size of 5 to 40 μI, preferably 15 to 20 μI.
40-50 parts were uniformly dispersed on FVd.

The transfer belt constructed in this manner was assembled into the apparatus shown in Figure 8, and a 10,000 sheet feeding experiment was conducted.

Diameter of photoreceptor 1: 60 mm, process speed: 50 mm/
SeC, the electrode roller 83 has a diameter of 82 mm and a hardness of Asker.
C307i, EPD with volume resistance 105~1o6Ωcm
Photoconductor 1 when using M roller and passing through transfer belt 82
The nip width was 4 mm, the length was 220 mm, and the contact pressure was 10 C)-120 gr/cm2.

Although the experiment was conducted under all environments, no image deletion or toner fusion occurred even under the most severe H/Hffi conditions.

The belt surface is not limited to the above method, and it goes without saying that materials such as inorganic abrasives and magnetic powders described in the above-mentioned embodiments can also be used. Of course, it is also possible to form a rough surface and provide an appropriate circumferential speed difference between the photoreceptor and the photoreceptor.

(3) As described in detail, according to the present invention, an image carrier;
In an image forming apparatus equipped with a transfer means that presses against the transfer means, by making the transfer means have a multilayer structure, it is possible to expand the selection range of materials, and with this, stable and good transfer can be achieved over a long period of time. By actively polishing the image carrier,
Since it can sufficiently resist environmental changes and always provide good transfer performance, it has a remarkable effect on obtaining high-quality images.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of essential parts showing the configuration of an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of the same transfer roller. FIG. 3 is a partially enlarged sectional view showing the surface structure of the transfer roller, FIGS. 4 and 5 are enlarged sectional views of other embodiments showing the surface structure of the transfer roller, and FIG. 6 is an enlarged sectional view of another embodiment showing the surface structure of the transfer roller. FIG. 7 is a sequence showing the operation of still another embodiment; FIG. 8 is a side view of main parts of an image forming apparatus showing an embodiment using a transfer belt. , FIG. 9 is an enlarged sectional view showing the structure of the transfer belt, and FIG. 1O is a schematic side view for explaining the structure and operation of a known image forming apparatus. l...Photoreceptor, 2.12...Transfer roller, 3.13
...Charging roller, 4...Power source, 5...Image signal,
6...Developer, 8...Cleaner. Figure Figure Figure 4 Figure Figure Figure Figure 0

Claims (1)

[Claims] (1) In an image forming apparatus equipped with an image carrier and a transfer means in contact with the image carrier, the transfer means has at least two layers, and the surface facing the photoreceptor is formed into a rough surface. Transfer device. (2) The transfer device according to claim 1, wherein the transfer means is a transfer roller. (3) Claim 1 in which the transfer means is a transfer belt
Transfer device described in Section 1. (4) The transfer device according to any one of claims 1 to 3, wherein the means for forming a rough surface is minute irregularities formed on the surface of the transfer means. (5) The transfer device according to any one of claims 1 to 3, wherein the means for forming a rough surface is hard particles dispersed in the surface layer of the transfer means. (6) Claims 1 to 3 in which the means for forming a rough surface comprises braided fibers attached to the surface of the transfer means.
The transfer device according to any one of paragraphs. (7) The transfer device according to any one of claims 1 to 6, wherein a speed difference is created between the photoreceptor and the transfer means when paper is not passed.