JP2002174956A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device by which the stabilization of a transfer nip, accurate positioning, the improvement of the transfer property of cardboard and the improvement of reliability are attained. SOLUTION: A transfer belt 6 always comes into contact with a photoreceptor 3 at a home position regardless of the existence/absence of the entering of transfer paper, and is always in a contact state and is always in a nip forming state in timing other than specified timing. The photoreceptor 3 and the transfer belt 6 are separated only in the timing by which toner replenishment is controlled by sticking a pattern to the photoreceptor 3. When it comes to the position of the pattern, an arm 20 is depressed through cam 19, the arm 20 and a lever 21 by a clutch 18, and a belt unit is released downward, so that the transfer belt 6 is separated from the photoreceptor 3. Since the pattern is not stuck to the transfer belt 6, the risk of the occurrence of toner staining on the transfer belt 6 is eliminated and a cleaning property is stabilized, so that the back staining of the transfer paper is not caused.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus.

[0002]

2. Description of the Related Art For a conventional transfer belt used in an image forming apparatus such as a copying machine, a material which does not contaminate a photoreceptor and which can be used for a rubber material of an inner layer of the belt has been developed. Did not. For this reason, when the time for which the transfer belt is brought into contact with the photoconductor is prolonged, there is a problem that a substance that contaminates the photoconductor is deposited from the belt and contaminates the photoconductor. Using a contaminated photoreceptor
There is a problem that white spots occur in an image.

Further, in the coating layer of the transfer belt, there is no material having a stretch that can be blocked by the coating layer, even if the material pollutes the photoreceptor. That is, since the photoconductor is contaminated with the conventional transfer belt, the transfer belt and the photoconductor have to be separated from each other.

That is, in the conventional belt transfer system, the home position of the transfer belt is a position away from the photosensitive member, and only when the transfer paper enters, that is, at the time of transfer, the transfer belt rises by the solenoid or the like and moves to the photosensitive member. The contact system is adopted.

However, this method has a problem that the transfer nip cannot be stabilized, and when thick paper or the like enters, a transfer failure or the like occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus in which the transfer nip is stabilized, accurately positioned, the transferability of thick paper is improved, and the reliability is improved.

Further, in view of the fact that there is no elongating material that can be blocked by the coat layer even in the case of a material that contaminates the photoreceptor, the deposition of contaminants can be reduced by making the surface of the member at least two or more. It is an object of the present invention to provide an image forming apparatus which aims to prevent the occurrence.

It is a further object of the present invention to provide an image forming apparatus which achieves high durability and long life of the entire image forming system.

[0009]

In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention carries an image carrier carrying a toner image and a sheet, and attaches the image to a carried sheet. Image forming apparatus having endless contact transfer / transport means for transferring a toner image on a carrier, cleaning means for cleaning the contact transfer / transport means, and stretching means for stretching the contact transfer means Wherein the contact transfer / transporting means is operated while being in contact with the image carrier, except during control for attaching toner to the image carrier during image formation control or the like.

According to a second aspect of the present invention, in order to achieve the above object, in the image forming apparatus of the first aspect, the contact member constituting the contact transfer / transport means has at least two layers. I do.

According to a third aspect of the present invention, in the image forming apparatus of the first aspect, in order to achieve the above object, the outermost layer of the member constituting the contact transfer / transporting means has an expansion rate of at least when a crack occurs. It is characterized by being 50% or more.

According to a fourth aspect of the present invention, in order to achieve the above object, in the image forming apparatus of the first aspect, the expansion ratio of the member of the contact transfer / transporting means at the time of occurrence of a crack is reduced when the member is stretched. The expansion ratio is 10 times or more.

According to a fifth aspect of the present invention, in order to achieve the above object, in the image forming apparatus according to any one of the first to fourth aspects, a lubricant application means is provided on the image carrier or the contact transfer conveyance means. Is provided so that a lubricant can be applied.

According to a sixth aspect of the present invention, in order to achieve the above object, in the image forming apparatus of any one of the first to fifth aspects, the image carrier is an amorphous silicon photosensitive member. .

[0015]

Embodiments of the present invention will be described below with reference to the drawings. In addition, as an example of a member constituting the contact transfer conveyance unit, a tube-shaped transfer roller or a belt can be given. In all the embodiments described below, a transfer belt is described, but a transfer roller may be used.

An embodiment of the present invention using a transfer belt as an example will be described below. First, a transfer conveyance device used as an embodiment of the present invention will be described. The transfer / conveying apparatus denoted by reference numeral 1 in FIG. 1 supports the belt unit 2 detachably from the main body 1A. The belt unit 2 transfers the transfer belt 6, which is wound around a pair of rollers 4, 5, to the photoconductor 3 to transfer the developed image from the drum-shaped photoconductor 3 shown in FIG. DC to contact and separate
A solenoid 8 and a contact / separation lever 9; a bias roller 11 for applying a transfer bias to the transfer belt 6;
And a contact plate 13 for removing the electric charges from the contact plate 13. A cleaning device 16 having a cleaning blade 16A for scraping off paper dust and the like from residual toner and transfer paper S adhered to the surface of the transfer belt 6 and a high voltage power supply 12 for applying a voltage to the bias roller 11 are provided in the main body shown in FIG. 1A.

The roller 5 has a gear 5b connected to a drive motor (not shown) as shown in FIGS. 1 and 2, and is driven to rotate. The transfer belt 6 can move in the transport direction of the transfer paper S (the direction of the arrow A in FIG. 3) at a position facing the photoconductor 3 following the rotation of the roller 5. As shown in FIG. 5, the transfer belt 6 has a two-layer structure. When the electric resistance measured according to JIS K6911 is 100 V DC, the surface layer 6 b as a coat layer has a surface resistivity of the belt surface. 1X10 ⁹ Ω~1 × 10 ¹² Ω, the surface resistivity of the inner layer 6a is ^{1 × 10 7 Ω~1 × 10 9} Ω, and a volume resistivity of ^{5 × 10 8 Ω · cm~5 ×} 10 10 It is set to Ω · cm.

The rollers 4 and 5 are rotatably supported by a support 7 as shown in FIGS. The support 7 can swing about the support shaft 5 a of the roller 5, which is located downstream of the transfer position with respect to the photoconductor 3, in the transfer paper conveyance direction indicated by the arrow A among the rollers 4 and 5. . The support 7 is operated by a DC solenoid 8 driven on the transfer position side of the transfer belt 6 by a signal from a control plate 8A. That is, the DC solenoid 8
, A contact / separation lever 9 is connected, and the contact / separation lever 9 moves the support 7 to move the transfer belt 6 toward and away from the photoconductor 3.

The leading edge of the transfer paper S conveyed in a state where it is aligned with the leading edge position of the image formed on the photoreceptor 3 by the registration roller 10 serving as a paper transporting means is transferred to the photoreceptor 3 by the control plate 8A. When approaching, a drive signal is issued to drive the DC solenoid 8. Therefore, the driving of the solenoid 8 causes the support member 7 to move the photosensitive drum 3
The transfer belt 6 comes into contact with the photoconductor 3 in close proximity to the photoconductor 3, thereby forming a nip portion B at which the transfer paper S can be conveyed while being in contact with the photoconductor 3 at a position facing the photoconductor 3. You.

Among the rollers 4 and 5 described above, the roller 4 located on the photosensitive member 3 side is configured as a driven roller with respect to the roller 5 on the driving side, and the surface shape of the roller 4 is shown in FIG. Thus, both ends 4a in the axial direction,
4a is formed in a tapered shape, and the transfer belt 6
To prevent biasing. Although the roller 4 is a conductive roller made of metal or the like, it only supports the belt having the electric resistance as described above, and may not be electrically connected directly to other conductive members. Further, the roller 4 can be fed back to the high voltage power supply 12 like a contact plate 13 described later to be grounded.

The roller 5 on the driving side has a function of increasing the gripping force on the transfer belt 6 at the time of driving.
A material such as chloroprene rubber or silicone rubber is selected. Also, a conductive roller can be used without using rubber for the roller 5. It is also possible to return the feedback current from the roller 5 to the high voltage power supply 12.

When the rollers 4 and 5 are grounded, a transfer control plate 14 to be described later is connected to the rollers 4 and 5. It is also possible to ground both rollers 4 and 5 at the same time and feed back the feedback current.

The bias roller 11 is provided on the downstream side of the roller 4 in the moving direction of the transfer belt 6 (the left side in FIGS. 3 and 4) so as to contact the inside of the transfer belt 6. The bias roller 11 constitutes a contact electrode for applying a charge having a polarity opposite to the charge polarity of the toner on the photoconductor 3 to the transfer belt 6.
It is connected to the.

The contact plate 13 is arranged on the inner surface of the transfer belt 6 near the lower driven roller 4 which is not the transfer paper transfer surface, and injects electric charge to the transfer paper S upstream of the transfer nip as described later. Is suppressed. This contact plate 13
Is for detecting a current flowing on the transfer belt 6 as a feedback current, the current supplied from the bias roller I ₁ by the detection of this current is controlled. For this reason,
The contact plate 13 has a bias roller I ₁ according to the detected current.
A transfer control plate 14 for setting a current to be supplied to the transfer control plate 14 is connected to the high-voltage power supply 12.

In such a transfer / transport apparatus 1, as shown in FIG. 4, the support 7 moves the transfer belt 6 closer to the photoconductor 3 as the transfer paper S is fed out from the registration roller 10. And a width of 4 to 8 mm corresponding to the length of the transfer paper between the photosensitive member 3 and the transfer direction.
A nip portion B is formed.

On the other hand, in the case of an analog machine, the surface of the photoreceptor 3 is charged to, for example, -800 V. As shown in FIG. 6, positively charged toner is electrostatically adsorbed on this surface. Move to the nip in the state. The photoreceptor 3 is disposed near the photoreceptor 3 before reaching the nip portion, and a pre-transfer neutralization lamp (PTL) for weakening the charge on the surface of the photoreceptor 3.
15 reduces the surface potential. In FIG. 6, the height of the charged charges is represented by the size of a circle, and the state in which the charged charges are reduced by the pre-transfer charge removing lamp 15 is shown smaller than the circle before the charge removal.

In the nip portion B shown in FIG.
Toner above is transferred onto the transfer sheet S by a transfer bias from the bias roller I ₁ located in the transfer belt 6 side. The transfer bias is applied from the high voltage power supply 12 in the range of -1.5 kV to -6.5 kV. The transfer bias is variably set as a result of the constant current control as described below. That is, in FIGS. 3 and 4, the current value output from the high-voltage power supply 12 is I _1, and the value when the feedback current value flowing from the contact plate 13 to the ground via the transfer belt 6 is I ₂ . If, I ₁ -I ₂ between these two = I _OUT (However, I _OUT: constant) controlling the value of I ₁ so that the relation is obtained. This is to stabilize the surface potential Vp on the transfer paper S and eliminate the change in transfer efficiency, regardless of changes in environmental conditions such as temperature and humidity and variations in the manufacturing quality of the transfer belt 6. It is.

That is, the current flowing to the photoconductor 3 through the transfer belt 6 and the transfer paper S is regarded as I _OUT , so that the surface resistance on the transfer paper S can be reduced or increased by increasing the resistance to the transfer belt 6. A change in the ease of current flow is prevented from affecting the separation performance and transfer performance of the transfer paper S. Current I _OUT is conveying speed 330 mm / sec, and good transfer can be obtained in the case of setting the I _OUT = 35uA ± 5 .mu.A in the effective bias roller length 310 mm.

When the image is transferred from the photoconductor 3, the transfer paper S is also charged at the same time. Therefore, the transfer paper S is electrostatically attracted onto the transfer belt 6 and the transfer paper can be separated from the photoconductor 3 by the relationship between the true charge of the transfer belt 6 and the polarization charge generated on the transfer paper S side. . Then, the transfer paper S itself is promoted by a peeling operation based on the stiffness of the transfer paper S utilizing the curvature separation of the photoconductor 3.

However, in such electrostatic attraction, when the humidity is high due to a change in environmental conditions, a current easily flows through the transfer sheet S, so that the transfer sheet cannot be separated properly.
For this reason, since the resistance value of the surface layer 6b of the transfer belt 6 shown in FIG.
The transfer of the true charges to the transfer paper S in the above is delayed, and the bias roller 11 is positioned downstream of the nip portion B in the transfer paper transport direction. Thus, the transfer of the true charges from the transfer belt 6 to the transfer sheet S is delayed, and the electrostatic attraction between the transfer sheet S and the photoconductor 3 is avoided.

To delay the transfer of the true charges used in this case means that no charges are generated on the transfer sheet S upstream from the transfer sheet S to the nip portion on the photosensitive member 3 side. This prevents the transfer paper S from being wound around the photoconductor 3 and also prevents the transfer paper S from separating from the photoconductor 3 from being poorly separated.

Further, it is preferable that the transfer belt 6 be selected from those having a small resistance change due to an environmental change. As a conductive material for controlling the resistance, an appropriate amount of carbon or zinc oxide is added, and a rubber belt is used as an elastic belt. In the case where is used, it is desired to select a material having a low hygroscopicity and a stable resistance value, such as chloroprene rubber, EPDM rubber, silicone rubber, epichlorohydrin rubber and the like.

The current I _OUT flowing to the photoconductor 3 side
Is not unique and can be reduced when the transport speed is low, and can be increased when the transport speed is high or when the pre-transfer neutralization lamp 15 is not used.

On the other hand, the transfer paper S passing through the nip B is
The transfer belt 6 is electrostatically attracted and conveyed in accordance with the movement of the transfer belt 6, and the roller 5 on the driving side separates the curvature. For this reason, the diameter of the roller 5 is set to 16 mm or less. further,
When such a roller 5 is used, an experimental result has been obtained that it is possible to separate ^high- quality 45K paper (rigidity 21 cm 3/100).

The transfer paper S separated from the transfer belt 6 by the driving roller 5 is guided by a guide plate and is fixed by a fixing unit 17.
Is transported between the heating roller 17a and the pad roller 17b. The fixing unit 17 heats and melts the toner on the transfer paper S and presses the toner on the transfer paper S to fix the toner on the transfer paper S.

When the transfer of the image onto the transfer paper S and the separation of the transfer belt 6 are completed, the contact / separation lever 9 is released in response to the excitation of the DC solenoid 8 being released, and the support 7 is separated from the photoreceptor 3. Is done. Then, the surface is cleaned by the cleaning device 16.

The cleaning device 16 is provided with a cleaning blade 16A, and the toner transferred from the surface of the photoreceptor 3 or scattered around the transfer belt 6 without being transferred by rubbing the transfer belt 6. Is scraped off the toner and the paper powder of the transfer paper S when the toner adheres.

The transfer belt 6 rubbed by the cleaning blade 16A has a low friction coefficient to prevent the phenomenon such as an increase in driving force due to an increase in rubbing resistance or a turn-up of the cleaning blade 16A. It is coated with a systemic resin material amount, for example, polyvinylidene fluoride, ethylene tetrafluoride, or the like. The toner or paper dust written from the surface of the transfer belt 6 is stored from the main body 1A into a waste toner collecting container (not shown) by the collecting screw 16B.

In the above-described drawings, the application electrode for detecting the surface resistance of the transfer belt 6 is omitted. As an example of the application electrode, a roller or the like in contact with the surface of the transfer belt 6 can be given. The above description is only for an analog copier. For example, the photoconductor is negatively charged and has a positive toner.
It goes without saying that the present invention can be applied to a digital machine using a minus toner.

In the above example, the bias roller is used as the bias applying means. However, a CG or a brush may be used. The installation position may be either upstream or downstream of the nip portion with the drum. The same applies to the configuration of the driving roller and the driven roller. Further, although the belt and the photosensitive member are all separated by a solenoid, it is also possible to adopt a configuration using a cam and a clutch as described later, in addition to the solenoid.

FIG. 7 shows a first embodiment of the present invention in which the transfer belt 6 is brought into contact with the photosensitive member 3. The transfer belt 6 and the photoconductor 3 are always in contact regardless of whether or not the transfer paper S has entered. In other words, in the apparatus of the present embodiment, the photosensitive member 3 and the transfer belt 6 are always in contact with each other at the standby time of JOB, that is, at the home position. In the conventional apparatus, the unit including the transfer belt 6 is moved up by a driving unit (not shown) such as a solenoid to form a nip by contacting the photosensitive member 3 only when the transfer paper S enters. In the embodiment, the state is always contact and nip formation except at a predetermined timing. The predetermined timing is, as shown in FIG. 7A, the toner replenishment control based on the amount of adhesion when a certain pattern is placed on the photoconductor 3 in order to control the toner replenishment. Photoconductor 3
The photosensitive member 3 and the transfer belt 6 are separated from each other only at the timing when the toner replenishment control is performed by attaching the toner to the photosensitive drum 3 (see FIG. 7C).

More specifically, when the position of the pattern is reached, the cam 18, the arm 20, the lever 21
, The belt unit is released downward, and the transfer belt 6 is separated from the photoconductor 3. When the above-mentioned pattern is adhered to the photoconductor 3, when the transfer belt 6 is always in contact with the photoconductor 3, the pattern adheres from the photoconductor 3 onto the transfer belt 6,
This causes the toner on the transfer belt 6 to be stained, and the cleaning property is reduced. Therefore, the transfer belt 6 is separated from the photoconductor 3 only when a pattern is formed on the photoconductor 3.
If the two are separated from each other, the pattern does not adhere to the transfer belt 6, so that there is no danger of toner stain on the transfer belt 6, and the cleaning property is stabilized, and the back stain of the transfer paper does not occur.

FIG. 7A is a timing control chart of the belt transfer system of the present embodiment. FIG. 7A shows the timing of development and transfer. As can be seen from the figure, the transfer belt 6 is turned on after the solenoid for bringing the unit including the transfer belt 6 into and out of contact with the photoconductor 3 is turned on.
Is separated from the photoconductor 3. Thereafter, a P sensor bias is applied, the pattern is adhered to the photoconductor 3, and the sensor detects the amount of adhesion. At this time, since the transfer belt 6 is separated from the photoconductor 3, the transfer belt 6 is not stained with the toner, and the amount of the pattern adhered on the photoconductor 3 is not transferred to the belt. Detection can be performed as before.

The above-described example is an example in which the transfer belt 6 is separated when a pattern is adhered to the photosensitive member 3 during toner replenishment control. When the control for forming a pattern is performed, the transfer belt 6 may be separated from the photoconductor 3.

As described above, the advantage in the case where the home position of the transfer belt 6 is always in contact with the photosensitive member 3 is as described above, but the disadvantage is that the photosensitive member 3 is contaminated. Yes, they are in a trade-off relationship. Therefore, in the present embodiment, as described above, the problem is solved by providing the transfer belt 6 with the surface layer 6b which is a coat layer. That is, the substance which causes contamination of the photoconductor 3 by providing the surface layer 6b which is a coat layer is blocked. Although FIG. 5 shows the case of a transfer belt, in the case of a transfer roller, a tube may be placed on the outside to block contaminants.

The contamination of the photoreceptor 3 can be effectively prevented by setting the characteristic values of the coat layer as follows. The data when a 500K run is performed using an actual machine is shown. If the elongation at the time of crack generation is 50% or more, contamination of the photoreceptor 3 does not occur over time including the initial period. FIG.
(A) shows the relationship between the elongation rate of the transfer belt and the contamination of the photoreceptor. It can be seen that the higher the elongation rate, the less the contamination of the photoreceptor 3. Further, a transfer belt having an extension rate of 50%
After the endurance run was performed, the photoreceptor contamination was evaluated (leaved in an H / H environment for 10 days). In this evaluation, no photoreceptor 3 contamination occurred. From the above, it can be seen that there is no problem if the elongation ratio at which no photoconductor contamination occurs is 50% or more. Therefore, it can be said that there is no problem even if there is a contaminant on the inner layer 6a (for example, rubber layer) side as long as the coat layer has such characteristics.

When the transfer belt is used, the transfer unit is stretched and used. FIG. 8 shows the relationship between the extension of the transfer unit and the elongation of the belt (the rate of expansion when a crack occurs).
(B) and (C) show. It can be seen that no photoconductor contamination occurs when the ratio between the crack extension ratio and the stretching extension ratio is approximately 10 or so.

However, it is not enough to simply use a transfer belt having a high extension rate.
Considering deterioration over time, such as deterioration at the contact portion with 6A, the relationship between the extension rate of the transfer belt and the extension at the time of use in the transfer unit is (extension rate at occurrence of crack) ≧
(Elongation ratio when belt is stretched) × 10. That is, since the coating layer on the surface of the transfer belt is often deteriorated because it is cleaned with the cleaning blade 16A or the like or is brought into contact with the photosensitive member 3 with time, when the coating layer is deteriorated, contaminants from the coating layer are removed. It is deposited and photoconductor contamination occurs. The above relationship shows characteristics taking into account the degradation of the coat layer over time.

The elongation at the time of occurrence of a crack refers to the elongation at which a crack occurs in the coating layer when the transfer belt is expanded until a crack occurs, and is related to the elongation of the transfer belt. Cracks are generally C
This is a crack when the belt surface is viewed with a CD or the like. Usually, observation is performed at a magnification of about 100 to 400 times.

The photosensitive member 3 can be an amorphous silicon photosensitive member. The photoreceptor 3 can further have a surface layer on the photoconductive layer formed on the support. The amorphous silicon surface layer is mainly moisture resistant,
Continuous repeated use characteristics, electrical pressure resistance, use environment characteristics,
Excellent durability. Since the amorphous silicon photoconductor 3 is generally used by being positively charged, the above embodiments may be used by positively charging.

The amorphous silicon photosensitive member will be described. This photoreceptor has a conductive support at 50 ° C. to 400 ° C.
° C, and vacuum deposition, sputtering, ion plating, thermal CVD, photo-CVD on this support
An amorphous silicon photoreceptor having an a-Si photoconductive layer (hereinafter referred to as "a-Si based photoreceptor") is formed by a film forming method such as a plasma CVD method. Among them, a plasma CVD method, that is, a method in which a raw material gas is decomposed by direct current, high frequency, or microwave glow discharge to form an a-Si deposited film on a support can be preferably used.

The layer structure of the amorphous silicon photosensitive member is, for example, as follows. FIG. 9 is a schematic configuration diagram for explaining a layer configuration. The electrophotographic photoreceptor 50 shown in FIG. 9A has a support 51 on which a-Si: H, X
And a photoconductive layer 52 having photoconductivity is provided. An electrophotographic photoreceptor 50 shown in FIG. 9B has a photoconductive layer 52 made of a-Si: H, X and having photoconductivity and an amorphous silicon-based surface layer 53 on a support 51. It is composed of An electrophotographic photoreceptor 50 shown in FIG. 9C has a support 51 on which a-Si: H, X
And a photoconductive layer 52 having photoconductivity, an amorphous silicon-based surface layer 53, and an amorphous silicon-based charge injection blocking layer 54. FIG. 9D
In the electrophotographic photoreceptor 50 shown in FIG. 1, a photoconductive layer 52 is provided on a support 51. The photoconductive layer 52 is a-S
i: A charge generation layer 55 of H and X and a charge transport layer 56, on which an amorphous silicon-based surface layer 53 is provided.

The support for such a photoreceptor may be either conductive or electrically insulating. As the conductive support, Al, Cr, Mo, Au, In, Nb, Te, V,
Metals such as Ti, Pt, Pd, and Fe, and alloys thereof;
For example, stainless steel is used. In addition, polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polystyrene, a film or sheet of a synthetic resin such as polyamide,
A support in which at least the surface on the side on which the photosensitive layer is formed of an electrically insulating support such as glass or ceramic is subjected to a conductive treatment can also be used. The shape of the support may be a cylindrical or plate-like endless belt having a smooth surface or an uneven surface, and the thickness thereof is appropriately determined so that a desired photoreceptor for an image forming apparatus can be formed. However, when flexibility as a photoreceptor for an image forming apparatus is required, it can be made as thin as possible as long as the function as a support can be sufficiently exhibited. However, the thickness of the support is usually 10 μm or more in terms of production, handling, mechanical strength and the like.

The amorphous silicon photoreceptor that can be used in the present invention has a charge injection between the conductive support and the photoconductive layer, if necessary, which has the function of preventing charge injection from the conductive support side. It is more effective to provide a blocking layer (FIG. 9C). That is, the charge injection blocking layer has a function of preventing charge from being injected from the support side to the photoconductive layer side when the photosensitive layer is subjected to a charging treatment of a fixed polarity on its free surface. It has a so-called polarity dependency in which such a function is not exerted when subjected to a charging treatment. In order to provide such a function, the charge injection blocking layer contains a relatively large number of atoms for controlling conductivity as compared with the photoconductive layer. The thickness of the charge injection blocking layer is preferably from 0.1 to 5 μm, more preferably from 0.3 to 5 from the viewpoints of obtaining desired electrophotographic characteristics and economical effects.
It is desirable that the thickness be 4 μm, most preferably 0.5 to 3 μm.

The photoconductive layer is formed on the undercoat layer as required, and the layer thickness of the photoconductive layer 52 is appropriately determined as desired from the viewpoint of obtaining desired electrophotographic characteristics and economic effects. Preferably, it is 1 to 100 μm, more preferably 20 to 50 μm, and most preferably 23 to 45 μm.

The charge transporting layer is a layer mainly having a function of transporting charges when the photoconductive layer is functionally separated. This charge transport layer contains a-SiC (H, F, O) containing at least silicon, carbon, and fluorine atoms as its constituent elements and, if necessary, hydrogen atom and oxygen atom. It has conductive properties, especially charge retention properties, charge generation properties and charge transport properties. In the present invention, it is particularly preferable to contain an oxygen atom. The thickness of the charge transport layer is appropriately determined as desired from the viewpoint of obtaining desired electrophotographic properties and economic effects, and the charge transport layer is preferably 5 to 50 μm, more preferably 10 to 40 μm, Most preferably, it is 20 to 30 μm.

The charge generation layer is a layer mainly having a function of generating charges when the photoconductive layer is separated in function. This charge generation layer is composed of a-Si: H containing at least silicon atoms as constituent elements, substantially containing no carbon atoms and, if necessary, containing hydrogen atoms, and has desired photoconductive properties, particularly charge generation properties. And has charge transport properties. The thickness of the charge generation layer is determined as desired from the viewpoint of obtaining desired electrophotographic characteristics, and economic effects, and the like,
Preferably from 0.5 to 15 μm, more preferably from 1 to 10
μm, optimally 1 to 5 μm.

The amorphous silicon photoreceptor that can be used in the present invention can be provided with a surface layer on the photoconductive layer formed on the support as described above, if necessary. It is preferable to form a silicon-based surface layer. This surface layer has a free surface and is provided mainly to achieve the required objects in terms of moisture resistance, continuous repeated use characteristics, electric pressure resistance, use environment characteristics, and durability. The thickness of the surface layer is usually 0.01 to 3
μm, preferably 0.05-2 μm, optimally 0.1-1
μm is desirable. Layer thickness 0.01
If the thickness is less than μm, the surface layer is lost due to abrasion or the like during use of the photoreceptor, and if it exceeds 3 μm, a decrease in electrophotographic characteristics such as an increase in residual potential is observed.

That is, the amorphous silicon photosensitive member has a high surface hardness and a semiconductor laser (770 to 800 nm).
m) shows high sensitivity to long-wavelength light such as m), and hardly deteriorates due to repeated use. Therefore, it can be used as an electrophotographic photosensitive member such as a high-speed copying machine or a laser beam printer (LBP). It should be noted that the amorphous silicon-based photoreceptor is usually used in positive charge, but it can be used in negative charge by doping of an impurity element or the like, so it is considered that there is no particular need to stick to the polarity (Japanese Patent Laid-Open No. 11-212286). Gazette).

Further, the lubricant is applied to the surface layer 6 of the transfer belt 6.
By applying the lubricant to b, the surface layer 6b can be further coated, and the lubricant is applied to the fine cracks of the coating, so that there is no adhesion of toner, and the above-described cleaning performance can be improved. Further, even when the frictional resistance μ is higher than that of the belt alone due to the application of the lubricant, the cleaning blade is not used, so that there is no side effect such as swelling. As shown in FIG. 10A, the lubricant 30 may be directly applied to the transfer belt 6 via the lubricant applying means 31. Similarly, FIG.
As shown in (2), it may be applied directly to the photoconductor 3. When applied to the photoreceptor 3, it is indirectly applied to the belt. Further, as shown in FIG. 10C, a cleaning roller 32 which is a cleaning unit for the transfer belt 6 is used.
May be applied. The timing of application can be at the time of belt exchange, operation of a programmable controller, or the like, and application can be performed at all times.

Examples of the lubricant include zinc stearate, barium stearate, calcium stearate,
Relatively higher fatty acids such as zinc oleate and manganese oleate may be used.

In the above description, the present invention is not limited to the above-described belt resistance, but may be lower or may be higher and reach the high resistance region. The transfer belt including the coat layer generally has two layers, but may have three or four layers. There are no particular restrictions on the material of the transfer belt,
Anything can be used as long as the above characteristic values are observed. For example, the coat layer may be formed using a material such as urethane.

[0063]

According to the first aspect of the present invention, as described above, since the image forming apparatus can be simply configured as a transfer apparatus, not only the reliability can be improved, but also a stable nip area can be secured, so that the transfer property can be secured. When the contact transfer / transport unit is separated from the photoreceptor, the unit of the contact transfer / transport unit rises during transfer, and when thick paper enters, In many cases, accurate transfer is not possible due to spreading to the paper thickness, and an abnormal image was sometimes generated.However, since the home position is always in contact, it is not exposed to the paper pressure. Since there is no occurrence, there are many effects that the transfer stability when thick paper is passed can be achieved.

According to the image forming apparatus of the present invention, in addition to the above-mentioned common effect, by making the coat layer of the contact transfer / transport means two or more, it is possible to prevent contamination of the photoconductor caused by the contact state, It is also possible to use a material that contaminates the photoreceptor, and there is an effect that a wide range of selections can be made on the material side of the contact transfer conveyance means.

According to the image forming apparatus of the third aspect, in addition to the above-described common effects, there is an effect that the photoconductor can be more stably prevented from being contaminated by defining the characteristics of the coating material.

According to the image forming apparatus of the present invention, in addition to the above-mentioned common effects, by defining the characteristics of the material when it is mounted on an actual machine, when the member is stretched and used, the deterioration of the coating layer over time The effect of preventing photoreceptor contamination is also provided in a form that also takes into account

In the image forming apparatus according to the present invention, in addition to the above-mentioned common effects, a lubricant is applied to block the contaminants from the contact transfer / transport means to the photosensitive member and to apply the lubricant to the contact transfer / transport means. Thus, there is an effect that it is possible to prevent the contaminant from flowing out from the contact transfer conveyance means.

According to the image forming apparatus of the present invention, in addition to the above-mentioned common effects, by using an amorphous silicon-based photoconductor, not only the contact transfer conveyance means but also the photoconductor can be prolonged in life. This has the effect of increasing the durability and extending the life of the entire system.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a transfer and conveyance device used as an embodiment of the present invention.

FIG. 2 is a plan view illustrating a basic configuration of the transfer / conveyance device of FIG. 1;

FIG. 3 is an image forming apparatus using the transfer conveyance device of FIG. 1;
FIG. 3 is a conceptual diagram showing a configuration in a state before a transfer operation.

FIG. 4 is a conceptual diagram during the transfer.

FIG. 5 is an enlarged cross-sectional partial view of a transfer belt used in the transfer conveyance device of FIG. 1;

6 is an enlarged view conceptually showing a state during transfer in an image forming apparatus using the transfer / conveyance device of FIG. 1;

7A is a timing control chart of the belt transfer system according to the embodiment of the present invention, FIG. 7B is a diagram showing a contact state, and FIG. 7C is a diagram showing a separation operation.

FIG. 8 is a diagram showing the relationship between the elongation rate and the contamination when a crack occurs in the transfer belt.

FIG. 9 is a schematic configuration diagram illustrating a layer configuration of an amorphous silicon photoconductor.

FIG. 10 is a diagram illustrating a structure of applying a lubricant to a photoconductor and a transfer belt.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transfer conveyance apparatus 1A Main body 2 Belt unit 3 Photoconductor 4, 5 Roller 6 Transfer belt 6a Inner layer 6b Surface layer 7 Support 8 DC solenoid 8A Control plate 9 Contacting / separating lever 10 Registration roller 11 Bias roller 12 High voltage power supply 13 Contact plate Reference Signs List 14 transfer control plate 15 pre-transfer static elimination lamp (PTL) 16 cleaning device 16A cleaning blade 16B recovery screw 17 fixing unit 17a heating roller 17b pad roller 18 clutch 19 cam 20 arm 21 lever 30 lubricant 31 lubricant applying means 32 cleaning roller 50 Electrophotographic photoreceptor 51 Support 52 Photoconductive layer 53 Amorphous silicon-based surface layer 54 Amorphous silicon-based charge injection blocking layer 55 Charge generation layer 56 Charge transport layer S Transfer paper B Nip

Claims (6)

[Claims] An endless contact transfer / transporting means for carrying an image carrier carrying a toner image and a sheet and transferring the toner image on the image carrier to the carried sheet; In an image forming apparatus having a cleaning unit for performing cleaning and a stretching unit for stretching the contact transfer unit, the contact transfer is performed except during control of attaching toner to the image carrier during image formation control or the like. An image forming apparatus, wherein a conveying unit is operated by contacting the image carrier. 2. An image forming apparatus according to claim 1, wherein said contact transfer and transfer means has at least two contact members. 3. The image forming apparatus according to claim 1, wherein the outermost layer of the member constituting the contact transfer / transporting means has an expansion ratio of at least 50% when a crack occurs. 4. The image forming apparatus according to claim 1, wherein an expansion ratio of the member of the contact transfer / transporting means when a crack occurs is:
An image forming apparatus characterized in that the extension ratio is 10 times or more when the member is stretched. 5. The image forming apparatus according to claim 1, wherein a lubricant applying means is provided on the image carrier or the contact transfer / transport means so that a lubricant can be applied. Image forming device. 6. An image forming apparatus according to claim 1, wherein said image bearing member is an amorphous silicon photosensitive member.