JPH02148074A - Image forming device - Google Patents

Abstract

PURPOSE:To reduce the size of a destaticizing means for the accumulated charge and to prevent the deformation and damage of a transporting means so as to maintain a transfer function over a long period of time by specifying the volume resistance and mechanical strength of a transfer material holding and transporting means which come into contact with an image carrier. CONSTITUTION:This device has a photosensitive body 11 of the image carrier and a transfer belt 12 which is suspended between grounded conductive rollers 15 and 16, comes into contact with the photosensitive body and travels in synchronization therewith. The belt 12 is made of the sheet member having the double layer constitution of the front layer which consists of a semiconductor layer consisting of polyvinylidene fluoride having the volume resistivity in a 10<8> to 10<15>OMEGA cm range and the rear layer which consists of an insulating resin layer consisting of polyethylene terephthalate having >=300kg/cm<2> tensile strength. The destaticization of the belt 12 is executed sufficiently by a small- sized destaticizing brush 17 in contact with a part of the surface and a roller 16 facing this brush. The device having the large mechanical strength to withstand long-term use is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (1. Title of the Invention (Field of Industrial Application) This invention relates to an image forming bag δ that uses an electrostatic transfer process, such as an electrostatic copying machine or a printer.

(Prior Art and Issues to be Solved) The transfer material is attracted and conveyed by a transfer material holding member such as a transfer belt made of a dielectric material or a transfer drum made of a dielectric film pasted on the surface of a cylindrical substrate, and the transfer material is held. An image forming apparatus has already been proposed in which the transfer material is passed through a transfer site formed by a member and an image carrier disposed opposite thereto, and the toner image on the image 1 (1 carrier side) is transferred to the transfer material. There is.

In such an image forming apparatus, the transfer material holding member needs to maintain a sufficiently high resistance value in order to reliably hold and transport the transfer material, but on the other hand, if the resistance value is too high, In the case of repeated operations, the holding member may not be able to completely eliminate the charge and the charge may accumulate, resulting in a so-called charge-up phenomenon, which may result in poor adsorption of the transfer material to the holding member, poor transfer, and the like.

In order to avoid such drawbacks, proposals have been made to remove static electricity by rubbing the transfer material holding member with a grounded brush or by applying alternating current corona discharge thereto. That is, a grounded brush is disposed opposite to a grounded conductive roller or the like via a transfer material holding member, and the brush is rubbed against the surface of the transfer material holding member, thereby removing the surface charge and removing the surface charge from the back surface. A method is known in which the electrical charge is removed by the conductive roller.

However, such a static eliminating means must be applied to both the front and back sides of the transfer material holding member at the same time, and therefore, although the conductive roller for removing the load on the back side can be arranged relatively freely, the brush for eliminating static electricity on the front side is , in areas other than the transfer material conveyance path,
Since the transfer material holding member must be placed so as to cover all I+, the space in which it can be placed is limited, and the deterioration of the brush itself may result in poor static removal due to the bristles. Hair plucking may have a negative effect on the image due to the hair.

In addition, in order to prevent the charge-up phenomenon, it has been proposed to use a relatively low-resistance semiconductive belt with a volume resistivity of about 1011 to 10" Ωcm. In such a case, it has been proposed to The electric charge on the belt surface can be removed by simply grounding the belt.

However, this type of belt is small in mechanical strength compared to dielectric belts, especially belts made of resin, and not only cannot withstand long-term use, but also causes transfer defects due to belt deformation. Rupture may occur.

This invention is like this! It was designed to deal with the problem of contact type transfers such as transfer bells and transfer bells.
In image forming apparatuses equipped with stages, it is strong enough to withstand long-term use, and effectively prevents charge amplifiers caused by poor static elimination.
It is an object of the present invention to provide an image forming apparatus that can perform stable and good transfer at all times.

(2) Structure of the invention (technical means for solving the problem and its operation) In order to achieve the object described in 1-1, the present invention provides an image carrier and a transfer material holder that adsorbs and conveys the transfer material by contacting the image carrier. In the image forming apparatus equipped with a conveying means, the transfer material holding and conveying means is a multilayer comprising a surface layer having a volume resistivity within the range of 108 to 1OIIiΩcI11 and a back layer having a tensile strength of 300 Kg/am'-L or more. It is characterized by being made of a sheet-like member having a structure.

With this configuration, in an image forming apparatus such as the one described in L, image quality can be prevented from deteriorating due to charge-up due to poor static elimination in the transfer material holding and conveying means, and the high mechanical strength of the means can prevent deterioration of the image quality. An image forming apparatus that can withstand long-term use can be obtained.

(Description of Embodiments) FIG. 1 is a perspective view of the main parts of an image forming apparatus using a transfer belt, showing an embodiment of the present invention, in which a cylindrical photoreceptor 11 rotating in the direction of arrow A, The conductive rollers 15 and 16 are suspended between ground conductive rollers 15 and 16, and are in contact with the photoreceptor 11. A transfer belt 12 is provided which runs in synchronization with the lever.

On the opposite side of the photoreceptor 11 across the transfer belt 12, a conductive material is applied by a power source 14 with a voltage having a polarity opposite to that of the toner of the toner image previously formed on the surface of the photoreceptor l1 to form a transfer electric field. A transfer roller 13 is provided.

The transfer material P supplied to the transfer belt 12 is electrostatically attracted to the belt + and conveyed, and at the transfer site where the transfer roller 13 is present, the toner image on the photoreceptor side is transferred to the transfer material, and further It is assumed that the image forming apparatus travels, is separated from the transfer belt, and is conveyed to a fixing site (not shown).

Reference numeral 18 denotes a cleaning blade for removing residual lubricant and toner remaining on the transfer belt without being transferred to the transfer material during transfer, and is made of adhesive material such as urethane, chloroprene, or NBR. shall be.

In such an image forming apparatus, the above-mentioned transfer bell I.
12, as shown in FIG. 2, consists of a conductive layer 121, an adhesive layer 22, and an insulating layer 123.

Insulating layer 123 is polyethylene terephthalate (PET)
The resin layer is preferably selected from resins such as , fluororesin, polyethylene, polyimide, borisulfon, etc., has a thickness in the range of 50 to 150 mm, and has a tensile strength of 300 kg/cm' or more. do.

To briefly explain the tensile strength test method, the test is JI
It was conducted in accordance with SK7113 (Plastic tensile test). As a test piece, PET5X50nu+
+, thickness 100 ALm was used. Holding both ends of the test piece, the test piece was placed in the direction of the pitcher's force at a test speed of 50 mm/
It was towed at min.

As a result, the tensile strength of the test piece I- was 1000 to 15
00 kg/cm'.

The semiconductive layer 121 is made of polyvinylidene fluoride, polyolefin thermoplastic/plastic elastomer, or polyester thermoplastic IIf.
Plastic elastomer, polyurethane thermoplastic elastomer,
Polystyrene-based thermoplastic elastomer, polyamide-based thermoplastic elastomer), fluorine-based thermoplastic elastomer),
An elastomer layer selected from ethylene-vinyl acetate thermoplastic elastomer, polyvinyl chloride thermoplastic elastomer, etc. In addition, a conductive filler such as carbon black, metal powder, or a titanium compound, nickel compound, silicon compound, etc. The volume resistivity of the elastomer layer was adjusted within the range of 108 to io+5 Ωcm by mixing a semiconductive feeler or changing the structure of the polymer, and the thickness was set within the range of 10 to 11001L. do.

Using the above-mentioned materials, an endless belt serving as a semiconducting layer member and an insulating layer member is formed by extrusion molding, centrifugal molding, etc., and these are overlapped and fixed by adhesion with an adhesive layer. The thickness of the insulating layer was 70JJ, Ill, the thickness of the semiconducting layer was 30m, and the thickness of the adhesive layer was 30Bm. The adhesive layer can be appropriately selected depending on the material of the insulating layer and the semiconductive layer.

In this way, we used a transfer belt i, which had a semiconductive layer on its surface and an insulating resin layer on its back surface, and brought the transfer roller into contact with the pressure nip between the transfer belt i and the photoreceptor. A concentrated electric field can be applied to the toner image on the photoreceptor, and transfer can be performed with high efficiency without causing any missing transfer even if the toner scatters.

Furthermore, in order to eliminate static electricity from the transfer belt in order to prevent charge-up due to peeling discharge when the transfer material is separated, there is no need to provide a discharge brush along the entire width of the transfer belt, as shown in the figure. A small static elimination brush 17 that contacts a part of the surface of the transfer belt, and a conductive roller 16 located opposite the brush with the belt in between.
A sufficient static elimination effect can be obtained by this.

In this way, the static elimination brush can be small, which is preferable since it is possible to avoid the adverse effect on the image due to hair loss. Further, as described above, since the transfer belt has high tensile strength, there is no risk of distortion or tearing of the belt, and stable transfer can be performed at all times.

FIG. 3 shows another embodiment of the invention. In this apparatus, four developing units 36a, 36b, 36c, and 36d each containing yellow, cyan, magenta, and black toner are sequentially loaded onto the surface of a rotating cylindrical photoreceptor 11 using a well-known process. A color toner image is formed, and the color toner image is transferred multiple times for each color onto a transfer material attached to the surface of a transfer drum 31 placed in contact with a photoreceptor 11 to form a color image.

In the illustrated apparatus, the transfer drum 31 has a frame body made of aluminum, SUS, etc., and a surface layer as shown in FIG.
It is made of a semiconductive elastomer that has been adjusted to a certain degree, and a multilayered sheet with an insulating resin layer on the back side is attached and formed.

The transfer belt used in the illustrated apparatus had a semiconductive layer with a thickness of 5071 m, an adhesive layer with a thickness of 30 LLm, and an insulating resin layer with a thickness of lOOg, m.

To briefly describe the operation of the illustrated device, the transfer material is electrostatically attracted to the transfer drum 31 by the action of the adsorption charger 37 to which a voltage of the same polarity as the transfer charge is applied and the grounded brush 38, and then The device 37 is turned off and the brush 38 is also released from the transfer drum 31.

Next, the toner image on the photoreceptor 11 is transferred onto the transfer material by an electric field generated by the conductive elastic blade 32 to which a voltage of opposite polarity to that of the toner image on the photoreceptor 11J- is applied. Such a transfer operation is repeated four times to form a color image on the transfer material, which is then neutralized by a pair of static eliminators 39, separated from the transfer drum 31 by separation claws 40, and then separated from the transfer drum 31 (not shown). It is assumed that the image is transported to a fixing site.

Conventionally, the sheet of the transfer drum in this type of device is
Normally, the device was constructed with only the charging ability in mind, so sagging and wrinkles were likely to occur, and there was a risk of poor transfer due to long-term use. Since the sheet is made of a large material and the static electricity can be easily removed as in the case of the above embodiment, stable transfer is possible at all times over a long period of time without the risk of transfer failure or color misregistration.

Note that when polyvinylidene fluoride is used as the semiconductive layer of the transfer belt, its dielectric constant is relatively large. It can be strongly adsorbed to the drum.

FIG. 4 shows still another embodiment of the present invention,
The photoreceptor, the transfer belt, and the conductive roller that suspends it are the same as those shown in the first figure, and corresponding members are designated with the same reference numerals.

The transfer belt 12 is made of a semi-conductive layer and an insulating resin layer, as described above.

The toner image formed on the surface of the photoreceptor is transferred to a conductive blade 4 disposed on the opposite side of the photoreceptor 11 with the transfer belt 12 in between, and to which a voltage of opposite polarity to the toner is applied by a power source 14.
By the action of 3, the image is transferred to the transfer material at the transfer site where the photoreceptor and the transfer belt come into contact.

The conductive blade 43 is made of the thermoplastic elastomer described in the first embodiment or a conductive material such as polyethylene, carphone black, metal powder, etc. I
It is preferable that the volume resistivity be adjusted to a range of 10 3 to 10 8 ΩC111 by mixing a feeler or changing the polymer 4VI structure of the material, and that the thickness be 0.03 to 5 mm.

It is assumed that the toner that did not contribute to the transfer reaches the cleaning device 45 as the transfer belt travels, and is removed by the conductive cleaning blade 44 attached to the cleaning device 45.

The conductive cleaning blade 44 is 5BR1BR,E
It is preferable to use PDM, urethane, silicone rubber, chloroprene, etc. mixed with carbon black or other conductive I-filler, and the hardness is preferably in the range of 50 to 80° (JISA hardness).

A conductive plate body 46 made of a conductive material such as aluminum or SUS is disposed at a position facing the cleaning blade across the transfer belt 12, and is a backing member that ensures the operation of the blade 440. In addition, together with the conductive plate 46, the electric charge accumulated on the belt surface is eliminated.

In this case, the volume resistance of the surface layer of the transfer belt 12 is 108
Since it is adjusted to ~10+5 Ωcm, the static electricity can be sufficiently eliminated by the blade member as described above, without using an object with a sharp tip such as a brush or a corona discharger as the static elimination member.

When using this device, hair loss caused by using a brush and image deterioration due to this can be avoided.
It is also effective in reducing costs.

(3) Effects of the invention As explained above, according to the present invention, the image 111
In an image forming apparatus equipped with a body and a transfer material holding and conveying means in contact with the body, by appropriately setting the volume resistance and mechanical strength of the lower stage of conveyance, it is possible to eliminate charges accumulated due to the charge-up phenomenon. , + of the lower transport stage
Static neutralization over the entire length in the 1J direction does not require stages and can be done using extremely small static neutralizing brushes, conductive blades, or other weight removing means, which is effective in reducing costs and saving space around the conveyance means. In addition, as a static elimination means,
When using a static eliminating brush, it is possible to avoid the negative effects on the image due to omissions, and when using a conductive blade, it is possible to further simplify the configuration by having it perform a cleaning function. be.

In addition, since the transfer material holding and conveying means uses a semiconductive material with a relatively high dielectric constant for the surface layer, it is easy to carry an electric charge and strongly adsorbs and holds the transfer material, thereby preventing transfer misalignment.
It is possible to effectively prevent color misregistration during color copying (17) and obtain high-quality images (by using a material with high mechanical strength for the surface, deformation and damage to the transfer material holding and conveying means can be prevented). This can be achieved by maintaining stable transcriptional function over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of an image forming apparatus to which the present invention is applied, particularly showing the transfer material conveyance mechanism, FIG. 4 and 4 are side views of main parts showing other embodiments of the present invention. 11φ photoreceptor, 12°. . Transfer belt, 13...
Transfer roller, ]5.16...φ conductive roller, 17---
Static elimination brush, 31...Transfer I/ram, 36a, 36b
, 36e, 36d-@-developing device, 43... conductive blade, 44... conductive cleaning blade, 4
6... Conductive plate. 7L M÷ (Method) April 7, 1989 Director General of the Japan Patent Office Yoshi 1) Tsuyoshi Moon 1 Patent Application for Display of Cases 1983-300705 2 Device for generating name image Jf of invention Relationship with the Ministry case for supplementation Applicant address name Canon Co., Ltd.

Claims (4)

[Claims] (1) In an image forming apparatus including an image carrier and a transfer material holding and conveying means that adsorbs and conveys a transfer material in contact with the image carrier, the transfer material holding and conveying means has a volume resistivity of 10^8 to 10.
The surface layer is within the range of ^1^5 Ωcm and the tensile strength is 3
An image forming apparatus comprising a sheet-like member having a multilayer structure and a back layer of 00 kg/cm^2 or more. (2) The surface layer of the transfer material holding and conveying means is made of polyvinylidene fluoride, polyolefin thermoplastic elastomer, polyester thermoplastic elastomer, polyurethane thermoplastic elastomer, polystyrene thermoplastic elastomer, polyamide thermoplastic elastomer, or fluorine thermoplastic elastomer. Claim 1: The invention is made of a thermoplastic elastomer selected from elastomer, polybutadiene thermoplastic elastomer, polyethylene thermoplastic elastomer, ethylene-vinyl acetate thermoplastic elastomer, and polyvinyl chloride thermoplastic elastomer. The image forming apparatus described in . (3) Claim 1 or 2, characterized in that the back layer of the transfer material holding and conveying means is a resin layer selected from polyethylene terephthalate, fluororesin, polyethylene, polyamide, polyimide, polycarbo, and polysulfone. The image forming apparatus according to any one of paragraphs. (4) The image forming apparatus according to any one of claims 1 to 3, wherein the transfer material holding and conveying means is an endless member that travels synchronously with the image carrier at a transfer site that comes into contact with the image carrier.