JPH056104A - Image forming device - Google Patents

Abstract

(57) [Abstract] [Purpose] An image that has more stable characteristics against changes in environmental conditions such as humidity, is easy to clean, and has a transfer means that is both functionally and economically superior. Providing a forming device. A transfer means is provided which is in contact with an image carrier via a transfer material and is composed of a conductive fixed contact member having elasticity. The conductive fixed contact member is biased to a side opposite in polarity to the developer. It is characterized in that an AC voltage is applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is obtained by forming an electrostatic latent image on an image bearing member such as a photoconductor in an electrophotographic apparatus, an electrostatic printer or the like, and developing the electrostatic latent image. The present invention relates to an image forming apparatus that transfers an image onto a transfer target such as paper.

[0002]

2. Description of the Related Art In a recording device such as an electrophotographic device or an electrostatic printer, after an electrostatic latent image is formed on a photoconductor, a developer is electrostatically attached to the electrostatic latent image to form a developer image. Formed, followed by
The developer image is recorded by being transferred onto a transfer target (called transfer paper, recording paper, etc.) by a transfer device. As this type of transfer device, electrostatic means such as corona transfer method and roller transfer method, and mechanical means such as adhesive transfer method are known.

In such a recording apparatus, since the electrostatic latent image and the developer that cannot be transferred remain on the photoreceptor after the transfer, the remaining developer is removed by the cleaning device, and subsequently, The electrostatic latent image is removed by a static eliminator. The recording apparatus repeats the above basic operations.

By the way, in recent years, along with the demand for downsizing of the apparatus, the harmfulness of ozone generated due to corona discharge has become a problem. Therefore, a means for removing ozone is provided, or roller transfer which generates less ozone is adopted. Is being considered. However, the roller transfer method has not been widely used while having such advantages. The reason is as follows.

That is, in roller transfer, it is required to press a transfer material (transfer paper) such as paper against the image surface of the developer on the photoconductor or the like with an appropriate pressure. If the amount is too large, the developer (toner) will stick and cause transfer omission, etc., so high mechanical accuracy (straightness of about ± 50 microns) and appropriate softness (JIS hardness of about 10 to 40 degrees) Is required. However, it is difficult to achieve both of them with the conductive rubber that has been conventionally used. In particular, when a recording paper having a thickness of 100 μm is used, an excessive pressure is generated to cause a transfer failure. Therefore, the transfer roller should be approached or separated according to the thickness. Complicated control is required. Also, the electric resistance for applying an electrostatic force to the toner image must be kept under a value that can prevent the destruction of the recording material due to electric discharge in all environments. Is constrained. Further, it is a demand for the surface property of the roller that makes the material selection strict, and a smoother surface with less frictional resistance is required for the roller surface to be easily cleaned for repeated long-term use. However, generally, the surface of the rubber material is rough, and the frictional resistance is particularly large. For this reason, conventionally, attempts have been made to replace the roller early without using a cleaning device, to limit the specification conditions, or to provide a surface material with higher lubricity on the roller surface. Instead of being improved, there are many technical difficulties such as the elastic properties being out of the requirement, and the price is more expensive than the corona transfer device. Also, they did not necessarily have sufficient environmental dependence. From such a background, there is a demand for a more excellent image forming apparatus that solves the above-mentioned problems and sufficiently satisfies the required characteristics.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has an extremely simple structure that generates less ozone, and can maintain an appropriate pressing force on a transfer material without mechanically high required accuracy. Image forming apparatus that is easy to perform, has less charge unevenness, exhibits more stable characteristics with respect to changes in environmental conditions such as humidity, and is easy to clean, and has excellent functional and cost advantages. The purpose is to provide.

[0007]

According to the present invention, an electrostatic latent image forming means for forming an electrostatic latent image on an image carrier, and a developing means for developing the electrostatic latent image to form a developer image. And a transfer means for transferring the developer image onto a transfer material, the transfer means slidably contacting the image carrier through the transfer material, and a conductive fixed contact member having elasticity, and this conductive material. An image forming apparatus is provided in which the static fixed contact member is provided with a developer and a means for applying an AC voltage biased to the opposite polarity side.

According to the present invention, an electrostatic latent image forming means for forming an electrostatic latent image on an image carrier, a developing means for developing the electrostatic latent image to form a developer image, and the developing means. A transfer means for transferring the agent image onto a transfer material, wherein the transfer means comprises:
A brush-shaped transfer member in which a conductive fiber having elasticity is formed in a brush shape, and the vicinity of the tip of the brush is in sliding contact with the image carrier through the transfer material, and a side of the brush-shaped transfer member having a polarity different from that of the developer. And a means for applying an AC voltage biased to the image forming apparatus.

Further, according to the present invention, an electrostatic latent image forming means for forming an electrostatic latent image on an image carrier, a developing means for developing the electrostatic latent image to form a developer image, and the developing means. A transfer means for transferring the agent image onto a transfer material, wherein the transfer means comprises:
An elastic, electrically conductive, flattened, flexible transfer member that is in sliding contact with the image carrier via the transfer material, and an alternating voltage biased to the developer on the flexible transfer member to the opposite polarity side. An image forming apparatus is provided, which comprises:

As the transfer means in the image forming apparatus of the present invention, a brush-shaped transfer member formed by forming elastic conductive fibers in a brush shape, or an elastic conductive plate transfer member is fixed. A contactor can be used.

[0011]

In the image forming apparatus of the present invention, a contact type transfer means using a contact made of a fiber, rubber or resin having elasticity and conductivity as a rubbing portion is used, and an AC voltage is used as a transfer bias. There is. Therefore, the environmental stability can be greatly improved as compared with the conventional transfer means, and a high-quality image without uneven charging can be obtained.
Further, it is possible to extremely easily and stably maintain an appropriate transfer pressing force only by a simple preparation for optimizing the density, thickness and length of the fiber or elastic body or the thickness and length of the plate material. At the same time, it is less susceptible to fluctuations in transfer characteristics due to the thickness of the transfer paper,
Furthermore, an image forming apparatus that generates extremely little ozone is realized.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of an electrophotographic apparatus equipped with a cleaning device according to an embodiment of the present invention. In FIG.
A photosensitive drum 1 as an image bearing member is rotatably provided in the direction of arrow A at a substantially central portion of a main body H of the electrophotographic apparatus. The photoconductor drum 1 is formed of an organic photoconductor (OPC) photoconductive material. Around the photosensitive drum 1, an image exposure device 3 including a charging charger 2, an LED (light emitting diode) array, a developing device 4, a transfer device 5, and a cleaning device 6 are sequentially arranged along the rotation direction of the photosensitive drum 1. There is.

The charging charger 2 is located above the photosensitive drum 1, and the surface of the photosensitive drum 1 is -500 to -500.
It is designed to be negatively charged substantially uniformly to -800 volts. The image exposure device 3 irradiates the surface of the photosensitive drum 1 with LED light according to the image information to be recorded, and forms an electrostatic latent image on the charged area. Further, the developing device 4 is provided with a hopper 7 for accommodating a one-component developer (toner) T having a triboelectric charging property, and inside the hopper 7, the developer T is slid on the photoconductor 1. A developing roller 8 for rubbing to develop the electrostatic latent image and an intermediate roller 9 for supplying the developer T to the developing roller 8 are provided.

The developing roller 8 is 10 ² ~ 10 ⁸ Conductive surface layer 1 made of a conductive elastic resin having an electric resistance of Ωcm
0, and an elastic layer 11 made of urethane foam, silicon rubber, EPDM, or the like, which is disposed inside the elastic layer 11.

An elastic blade 12 made of phosphor bronze, urethane, silicon resin or the like is pressed against the developing roller 8 for forming a thin layer on the surface of the developing roller 8 while frictionally charging the developer T. There is. The developer T passing between the developing roller 8 and the elastic blade 12 is charged with negative triboelectrification having the same polarity as the photoconductor drum 1 to form one or two developer layers. The material forming the surface of the developing roller 8 must be selected in consideration of triboelectric charging with the developer T, and in consideration of appropriate elasticity and friction.

Further, the developing roller 8 has a bias power source 1
3 is connected and is electrically connected to the conductive surface layer 10. As a result, a predetermined developing bias (-14
0 to −400 V) is applied to the developing roller 8.

The transfer device 5 is provided substantially below the photoconductor drum 1 so as to face the peripheral surface of the photoconductor drum 1 via a sheet conveying path 14. Transfer device 5
The main part of the structure is constructed as shown in FIG. 2a, for example. That is, the transfer device 5 bundles a supporting member 15a made of a conductive metal or the like and conductive fibers made of, for example, kneading conductive carbon with rayon into a plate shape with an appropriate density by the supporting member 15a. And a brush-like transfer brush 15b obtained by the above. Transfer brush 15
b is in sliding contact with at least the effective image width of the photoconductor 1 as the photoconductor 1 rotates.

A transfer bias is applied to the transfer brush 15b of the transfer device 5, and the transfer bias is
An AC voltage having an effective voltage of 500 to 1000 V in a frequency range of about 150 Hz to 4 kHz is biased to the polarity opposite to the polarity of the developer by 100 to 800 V.

When a transfer brush to which a transfer voltage is applied is brought into contact with the back surface of the transfer paper (recording paper) 16 conveyed here, the recording paper changes from about 300 to about 300, although it changes depending on the condition and humidity of the recording paper. The toner image on the photoconductor 1 is electrostatically attracted by being charged to 800 volts, and the toner image is transferred from the photoconductor drum 1 to the paper 16.

Another example of the transfer device is shown in FIG.
The conductive plate member 15c as shown in FIG. The conductive plate member 15c is made by kneading conductive carbon with elastic urethane rubber (resin) or silicone rubber (resin), and has a proper elasticity and conductivity of about 0.5 to 2 mm. It is made of a material that has excellent wear resistance and wear resistance. This conductive plate member 15c is also used, like the transfer brush 15b shown in FIG. 2a, with its free end in contact with the photoconductor 1 in the vicinity of the tip or with the tip abdominal surface with appropriate weight.

The fiber material of the conductive fiber forming the transfer brush 15b shown in FIG. 2a is not limited to rayon, but acrylic resin or the like has appropriate flexibility, mechanical strength, and dispersibility with carbon. Any of the above can be used in the same manner, but an example using a rayon brush will be further described below.

What is important in the transfer device 5 is the characteristics of the transfer brush 15b made of a conductive fiber. Below, the experimental results regarding the transfer characteristics, which were carried out by making various transfer brushes 15b by trial using various conductive fibers, are shown, and the preferable characteristics and shape are explained.

First, the electric resistance of the fiber is set as an effective resistance of 10 ⁴ Five types of transfer brushes were prototyped by changing in the range of -10 ¹⁰ ohm (Ω) / millimeter (mm). Ten kinds of transfer brushes were manufactured by changing the thickness of the fiber in the range of 0.5 to 30 denier. Furthermore, by changing the flocking density in the range of 1 line / mm (mm) to 2000 lines / mm, 10 kinds of transfer brushes are used, and the length of the brush fiber (effective length not including the supporting portion) is appropriately 2 to 30 mm. The prototype was made by changing the range. The transfer characteristics of the transfer brush made of these conductive fibers were examined by changing the pressing condition (mainly the bending amount = supporting angle) with respect to the photoconductor 1.

As a result, as a proper condition of the parameter, if the fiber length is 3 mm or less, it is difficult to obtain uniform contact with the entire transfer paper, and it is difficult to adjust the transfer characteristics. Three
In the range of up to 20 mm, it is mechanically good that the fiber has appropriate flexibility with a thickness of 1 to 8 denier, and the electrical resistance per fiber is 10 ⁵ ~ 10 ⁹ Good transfer characteristics were exhibited in the range of ohm (Ω) / millimeter (mm). Moreover, about 20-30 mm, about 5-15 denier showed the favorable result. Although not discussed, it is clear from the above results that a longer length will function in practice, but this will lead to an increase in the size of the device and lose its practical value.

The flocking density (number of fibers / unit length) is the thickness,
In addition to the length and the length, the strength with which the recording paper is pressed against the photoconductor 1 is determined. But,
Among these, the hair transplant density has another important factor.
That is, when the density is reduced below a certain level in order to adjust the pressing force, an image missing portion called transfer omission gradually appears in the transferred image in the form of streaks in the image advancing direction. This is because the recording paper is charged during transfer by the local discharge from the fiber tip to the recording paper due to the applied voltage, but if the fiber distance at the tip is too large, the recording paper is charged. It is understood that the image of this portion is not transferred and is missing because there is a portion that has not been formed. The condition of occurrence of this transfer omission varies depending on the type of recording paper used for transfer and the environmental humidity, but with a commonly used recording paper, when the relative humidity is about 30 to 70%, the fibers of the brush-like brush 15b are It was confirmed that when the tip-to-tip distance is about 1 to 2 mm or less, it is unlikely to occur.

From the above, the order of determining the above factors is
First, the flocking density should be determined (preferably by flocking a large number of fibers so as to be 1 mm or less), and then the thickness and length suitable for this should be determined. This required fiber density differs depending on the type of transfer paper used, and when a transparent film having high electric resistance is used as the transfer paper, the finest fiber density is required, and about 10 or more fibers per 1 mm are required. is necessary. However, normally used transfer papers can be used with about three or more. However, if the number of fibers is as small as possible, density unevenness due to uneven distribution of fibers over time tends to result in transfer defects, and the elastic force that mechanically presses the transfer paper also weakens. In addition, since it is easy to cause a problem that an elastic plate for backing up from behind the fiber is required, it is preferable to use as many fibers as possible as thin as possible.

When the optimum transfer conditions are extracted from the above examination results, the fiber transfer density of the brush-like transfer brush 15b is set to 3
The thickness is selected in the range of not less than 1 / mm (preferably 100 to 800 / mm), and the thickness of the fiber has appropriate flexibility of about 1 to 15 denier (this is in relation to the length). The length is about 3 to 30 mm, and the electric resistance per wire is 10 ⁵ ~ 10 ⁹ By adjusting the conductivity so as to be ohm (Ω) / millimeter (mm), it is possible to obtain the transfer brush 15b that exhibits optimum transfer characteristics.

This transfer device 5 to which an AC voltage is applied (fiber is 4 denier, length is 17 mm, number of fibers is 700 / mm)
In order to exhibit the high transfer characteristics under high humidity, which is a feature of, the comparison was made with the case where transfer was performed by applying only a DC bias voltage.

The results are shown in FIG. FIG. 3 shows a case where a DC voltage (1500 V) is applied to the same transfer device 5 (curve A in the figure) and an AC voltage of 1.2 kHz (effective value 1000 V, bias 600 V) is applied ( It is a comparison of the transfer efficiency for plain paper when the relative humidity of the environment of curve B) in the figure is changed in the range of 20 to 90%. The transfer efficiency is a value (%) obtained by dividing the weight of the toner transferred onto the recording paper by the weight before transfer and multiplying the value by 100.

As is apparent from FIG. 3, when the AC voltage is applied, the transfer efficiency is remarkably improved under the high humidity condition of 80% or more. This value is more than that obtained by the conventional corona transfer. It will be big. Although the clear principle of this effect is unknown, it is thought that the main factor is the effect of the voltage application time on the transfer paper whose conductivity is increased by moisture absorption in a humid atmosphere. It is considered that this is realized by changing the electric field within the time when the sum does not occur. In fact, the fact that the effect is not recognized at a low frequency such as 100 Hertz implies this, and the fact that the optimum frequency changes depending on the transfer speed means that the application of alternating current produces an effect different from direct current. Shows. Further, this effect exhibits the maximum effect when an elastic body such as a brush having a predetermined electric resistance is used as a contact in the present invention, and the recording paper is mechanically pressed against an image carrier such as a photoconductor, It is noteworthy that it shows markedly improved characteristics compared to the case of applying an AC voltage to the conventional corona transfer.

Further, as another remarkable effect, when a high resistance transfer recording paper such as a transparent transfer paper (so-called OHP paper) is used, streak-like image unevenness occurs due to dirt of the brush at DC. This is easy, but unevenness hardly occurs when AC is applied, and high image quality is maintained for a long period of time. This is presumed to be due to the fact that AC discharge has a property of causing less charge unevenness, and thereby exerts a large effect of improving image quality stability and an effect of reducing discharge unevenness with a small number of fibers.

FIG. 4 shows a prototype of a roller having a typical hardness (JIS 30 degrees) as a conventional conductive transfer roller, which is compared with a transfer brush. The rubber roller and the transfer brush are pressed against the spring scale to bite into it. The relationship between the amount (pressing distance) and the indicated value of the balance (value divided by the contact length) is shown. The respective rollers and transfer brushes have actually been subjected to an image transfer experiment, and the results show that the above-mentioned transfer omission occurs at a load of about 80 grams (g) / cm or more. Further, under a high humidity condition where the relative humidity is 80% or more even if the weight is too small, the mechanical adhesion was insufficient and transfer omission due to insufficient charging was observed at about 20 g / cm or less. Therefore, considering these in combination with FIG. 3, the amount of mechanical bite that can be properly transferred by the conventional transfer using the rubber roller is within a range of 0.1 ± 0.05 mm at the most, whereas the brush-like transfer brush 15b is used. Then 1.2
It shows a mechanical tolerance of about ± 0.7 mm, which is more than 10 times that of the conventional one, which contributes to easier parts accuracy and position setting, and can solve the problem of setting accuracy, which was a major obstacle in practical use with rubber rollers. I understand.

In order to maintain such mechanical precision, as shown in FIG. 5, the photosensitive member 1 of the support member 15a of the transfer brush 15b is provided.
The support angle θ with respect to the tangent between the transfer brush and the transfer brush is 0 to 60 degrees,
It is possible to adjust the biting amount (deflection amount), that is, the pressing force, by preferably fixing at about 5 to 30 degrees.

The reason why the brush tips are installed so as to be inclined toward the downstream side with respect to the tangent line of the photoconductor 1 is as follows.
This is not only for adjusting the pressing force but also for smoothly guiding the transfer paper entering the transfer area. The plate-shaped transfer member shown in FIG.
As shown in (3), it is convenient to perform the guide role by inclining it with respect to the photoconductor 1.

Incidentally, it is not preferable that the tip of the transfer brush 15b is lifted from the photoconductor 1 at the time of setting, and it is necessary to support the tip so that the tip comes into contact with the belly near the tip. This is because it is possible to achieve both a state where the charging unevenness is smallest in this state and a transfer sheet is easily passed through (which does not become a mechanical obstacle).

As described above, in the transfer by the transfer brush using the elastic fiber as in the present embodiment, the transfer paper pressing force can be extremely easily set to 80 g / cm or less, which is optimum for transfer, and a large mechanical allowance can be obtained. It has a great advantage that it can be maintained with a certain degree.

Since such a contact type transfer means exerts stable transfer characteristics even under high humidity, it has the effect of reducing the amount of residual transfer developer and reducing the cleaning load, and at the same time Since it also has the effect of removing paper dust, this also reduces the burden on the cleaning device and contributes to the improvement of reliability.

On the other hand, below the photosensitive drum 1, a paper feed unit 18 for supplying the paper 16 to the transport path 14 is provided. The paper feeding unit 18 accommodates the paper 16 to which the image is transferred. Above the paper feed unit 18, the paper 16 is conveyed from the paper feed unit 18 to the conveyance path 1 by rotation.
A sheet feeding roller 19 that supplies the sheet to the sheet 4 is provided. Further, at the end of the conveying path 14, a fixing device 20 for fixing the toner image after transfer onto the paper 16 is provided.

The toner image after development is conveyed to the transfer area facing the next transfer device 5, as described above. on the other hand,
The sheet 16 is sent from the sheet feeding unit 18 to the transfer area in synchronization with the rotation of the photosensitive drum 1 by the rotation of the sheet feeding roller 19. The back surface of the paper 16 is charged to a positive polarity by the transfer brush 15b. Therefore, the toner image on the surface of the photosensitive drum 1 is electrostatically attracted to the paper 16 and transferred. Here, the transfer brush 1
A voltage of 500 to 1000 V, which is biased to the polarity different from that of the developer toner by 300 to 800 V, is applied to 5b by the AC power source 21 via the conductive support 15a.

Since the transfer brush 15b is contaminated with toner and the like as it is used, in order to prevent it as much as possible, the rotating shaft 15 of the support member 15a is indicated by an arrow R in FIG.
It reciprocates around d, and is controlled so as to be separated and retracted from the photoconductor 1 in an area where there is no recording paper. As a result, the contamination of the transfer brush 15b can be extremely reduced, and there is no problem in printing about 1 to 20,000 sheets.

However, even in this case, cleaning is necessary for long-term use. For this reason, in this example, the transfer brush 15b is transferred from the AC power source 21 during transfer.
Voltage is applied to the toner, but at the time of non-transfer, a voltage of −100 to −300 V is applied by another power source 22 that generates a voltage of the same polarity (negative in this case) as the developer toner, or an alternating current By changing the biased component of the power source 21, the toner can be attached from the transfer brush 15b to the photoconductor 1 side, and the contamination can be prevented.

As another method for cleaning the transfer brush 15b, the transfer brush 15b in the non-transfer portion of the photoconductor 1 is used.
The toner is removed to some extent just by turning off the voltage applied to 0, and the cleaning effect can be obtained by passing the belt-shaped region in the non-transfer region where the charge of the photoconductor is zero through the transfer brush 15b. It is preferred to implement either of these cleaning means at the time of use.

By cleaning the transfer brush 15b as described above, a good transfer function could be maintained over 100,000 or more prints. Also, in the result of testing by changing the relative humidity of the environment in the range of 30 to 90%, under the environment of about 70% or more, the transfer efficiency is obviously higher than that of the method using corona transfer (before transfer of the transferred toner). It was also confirmed that the ratio of the toner to the amount of toner on the photoconductor) was exhibited. Note that the transfer device 5 is provided with a falling toner container 23 so that the toner may fall from the transfer brush 15b or the like.

Further, when a thin transfer paper is used, if the transfer paper is charged by the transfer member (transfer brush or the like) before contacting the electrostatic latent image carrier (photoconductor), the image carrier will be damaged. Part of the toner may fly (transfer) before it comes into close contact, resulting in an image defect such as a double image. As a countermeasure against this, as shown in FIG. 6, an insulating elastic plate 15 having a thickness of about 0.1 to 0.3 mm is provided on the transfer paper entry surface side of the transfer brush 15b.
Since e is fitted to the support 15a together with the transfer brush 15b, the transfer paper is not charged until just before the transfer paper comes into close contact.
The problems described above can be prevented. Further, as shown in FIG. 7, it is also effective to replace the mechanical characteristics of the brush fibers 15b with the elastic backup 15f similar to the elastic plate 15e on the brush 15b to increase the degree of freedom in brush design.

As described above, the recording apparatus according to the present embodiment uses the transfer device in which the AC bias is applied to the conductive transfer brush having elasticity. Therefore, it is possible to obtain high humidity resistance and uniformity of image quality with almost no generation of ozone. Further, since the transfer device is extremely inexpensive and the transfer device itself can be easily cleaned, it is possible to maintain good transfer with high efficiency over a wide range of environment for a long period of time. Also, since the conductive transfer brush directly contacts the transfer paper at the time of transfer, the paper dust adhering to the paper can be efficiently adsorbed and removed.
After transfer, the amount of attachments remaining on the photosensitive drum is extremely reduced, and the load on the cleaning device thereafter can be reduced. Further, the conductive transfer brush has a large mechanical tolerance when mechanically pressing the paper, so that the transfer omission (not to partially transfer) is effectively prevented, and especially when the conventional roller transfer method is used. Has a restriction such that a complicated countermeasure mechanism is required because the pressing force exceeds the permissible range when the thickness of the transfer paper becomes thicker, but the transfer according to the present invention has a large tolerance of the bite amount, which has an influence. It is possible to transfer a clear image regardless of the paper thickness. In addition, although the brush is used as an example in the above-mentioned embodiment, the present invention is not limited to this, and the plate thickness and the length are not limited to the case where the plate-shaped transfer member 15c other than the brush is used. The same function can be achieved by determining (the effective length in the contact bending direction), the support angle (adjustment of the biting amount, the pressing force) and the like in the same procedure as in the case of the brush.

[0047]

As described above, according to the image forming apparatus of the present invention, the contact type transfer means using the contact made of the fiber, rubber or resin having elasticity and conductivity as the rubbing portion is used. Since an AC voltage is used as the transfer bias, the environmental stability can be greatly improved as compared with the conventional transfer means, and a high quality image without uneven charging can be obtained. Further, it is possible to extremely easily and stably maintain an appropriate transfer pressing force only by a simple preparation for optimizing the density, thickness and length of the fiber or elastic body or the thickness and length of the plate material. At the same time, it is possible to realize the image formation in which the transfer characteristics are hardly affected by the thickness of the transfer paper and the ozone generation is extremely small.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a transfer brush and a plate-shaped transfer member used in the image forming apparatus of the present invention.

FIG. 3 is a graph showing the transfer efficiency when the relative humidity of the environment is changed in the range of 20 to 90%, comparing the case where a DC voltage is applied and the case where an AC voltage is applied.

FIG. 4 is a graph showing a relationship between a biting amount and a generated load between a conventional conductive transfer roller and a transfer brush of the present invention.

FIG. 5 is a diagram showing a state in which the transfer brush is installed with the brush tips inclined toward the downstream direction with respect to the tangent line of the photoconductor.

FIG. 6 is a diagram showing a transfer brush provided with an insulating elastic plate on the transfer paper entrance surface side.

FIG. 7 is a diagram showing a transfer brush provided with an elastic backup on the side opposite to the transfer paper entrance surface.

[Explanation of Codes] 1 ... Photosensitive drum, 2 ... Charging charger, 3 ... Image exposure device, 4 ... Developing device, 5 ... Transfer device, 6 ... Cleaning device, 7
... hopper, 8 ... developing roller, 9 ... intermediate roller, 10 ...
Conductive surface layer, 11 ... Elastic layer, 12 ... Elastic blade, 1
3 ... Power source, 14 ... Transport path, 15a ... Support member, 15b ...
Transfer brush, 15c ... Plate-shaped transfer member, 16 ... Paper (transferred material), 18 ... Paper feeding unit, 19 ... Paper feeding roller, 20
… Fixer, 21… AC power supply.

Claims (3)

[Claims] 1. An electrostatic latent image forming means for forming an electrostatic latent image on an image carrier, a developing means for developing the electrostatic latent image to form a developer image, and a transfer material for transferring the developer image. A transfer means for transferring to the image carrier, the transfer means slidingly contacting the image carrier via the transfer material, and having a conductive fixed contact member having elasticity, and a developer for the conductive fixed contact member. An image forming apparatus comprising: a unit that applies an AC voltage that is biased to the opposite polarity side. 2. An electrostatic latent image forming means for forming an electrostatic latent image on an image carrier, a developing means for developing the electrostatic latent image to form a developer image, and a transfer material for transferring the developer image. And a transfer means for transferring to the image carrier, wherein the transfer means forms elastic conductive fibers in a brush shape, and the vicinity of the tips of the brush is in sliding contact with the image carrier through the transfer material. An image forming apparatus comprising: a member; and a unit for applying an AC voltage biased to a side opposite to the developer to the brush-shaped transfer member. 3. An electrostatic latent image forming means for forming an electrostatic latent image on an image carrier, a developing means for developing the electrostatic latent image to form a developer image, and a transfer material for transferring the developer image. And a transfer means for transferring to the image carrier, the transfer means slidingly contacting the image carrier through the transfer material, and having elastic conductive flat extension member, and the flexible transfer member. An image forming apparatus, comprising: a member; and a unit for applying an AC voltage biased to the opposite polarity side to the developer.