JPH08171255A - Electrophotographic recorder - Google Patents

Abstract

PURPOSE: To provide an electrophotographic recorder capable of excellently maintaining the function of a photoreceptor drum over a long term by preventing the contamination of the photoreceptor drum. CONSTITUTION: A film 21c and a film 51c consisting of fluorine-contained resin having low reactivity on negative electrification type OPC applied to the photoreceptor drum 1 are respectively wound around the outermost periphery of an electrifying roller 7 and the outermost periphery of a transfer roller 8, so that a layer consisting of fluorine-contained resin is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic recording apparatus for recording an image by the electrophotographic system.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing a configuration example of a conventional electrophotographic recording apparatus. In the figure, reference numeral 1 is a photosensitive drum, and a negative charging type organic photosensitive material (OPC) is used as a photosensitive material. Around the photosensitive drum 1, a charging device 2, an exposure device 3, a developing device 4, a transfer device 5, and a cleaning device 6 are provided along the peripheral surface thereof.

In this electrophotographic recording apparatus, the photosensitive surface of the photosensitive drum 1 charged to -500 V by the charging device 2 is exposed by the exposure device 3 according to the image to be recorded, and an electrostatic latent image is formed.

Then, the developing device 4 develops the electrostatic latent image formed on the photosensitive surface of the photosensitive drum 1. Developing device 4
Holds the toner charged to the developing roller 41 with the same polarity as the charging potential of the photosensitive drum 1, and transfers the toner to the photosensitive drum 1.
Contact. A developing bias having the same polarity as the charging potential of the photosensitive drum 1 and a low voltage (for example, -200 V) is applied to the developing roller 41 from a developing bias power source (not shown), and the photosensitive drum is exposed by the action of the electrostatic latent image and the developing bias. Toner is selectively attached to the drum 1. That is, as shown in FIG. 4, toner is not attached to the charged portion (-500 V) on the photosensitive drum 1 because the photosensitive drum 1 side has a higher potential than the developing bias, and the exposed portion and the discharged portion ( For example, at −50 V to −100 V, toner adheres because the potential on the photosensitive drum 1 side is lower than the developing bias. Generally, such a developing method is called a reversal developing method.

Next, as shown in FIG. 3, the recording papers P fed out one by one from a paper feed cassette (not shown) by a paper feed roller (not shown) and a separation roller (not shown) as shown in FIG. In a state in which it is inserted between 1 and the transfer roller 51 of the transfer device 5, a transfer bias power supply 52 of the transfer device 5 applies a transfer bias of a predetermined voltage (for example, +1350 V) to the transfer roller 51 with a polarity opposite to that of the toner. Then, the toner is attracted to the transfer roller 51 side due to the influence of the transfer bias, and is transferred to the recording paper P. After that, on the photosensitive surface of the photosensitive drum 1, after the recording paper P is peeled off, the toner remaining without being transferred is removed by the cleaning device 6.

The charging device 2 is of the contact charging type and comprises a charging roller 21 as a contactor and a charging power source 22 for applying a voltage to the charging roller 21. The charging roller 21 is in contact with the surface of the photosensitive drum 1 and is driven to rotate, and when a voltage is applied from the charging power source 22, a discharge is generated between the charging roller 21 and the photosensitive drum 1 to charge the photosensitive drum 1. The charging roller 21 is the shaft 2
The elastic roller has a single-layer structure in which an elastic material 21b is bonded to 1a. The elastic material 21b is an EP in which a conductive filler such as carbon black or metal powder is dispersed to impart conductivity.
It is a rubber material or a sponge material made of DM, silicon, urethane or the like.

On the other hand, the transfer roller 51 in the transfer device 5
Is an elastic roller having a single layer structure in which an elastic material 21b is bonded to a shaft 21a. The elastic material 21b is a rubber material or a sponge material made of EPDM, silicon, urethane, or the like, which is made conductive by dispersing a conductive filler such as carbon black or metal powder.

[0008]

In the electrophotographic recording apparatus having the above structure, the charging roller 21 and the transfer roller 51 are included.
The cross-linking agent or uncrosslinked low molecular weight component added to the elastic materials 21b and 51b may exude. This is especially likely when the device has been idle for a long period of time.

By the way, the negative charging type OPC is apt to be contaminated by the substance exuding from the charging roller 21 and the transfer roller 51 as described above. Therefore, when the cross-linking agent or the uncross-linked low molecular weight component exudes from the charging roller 21 or the transfer roller 51 and adheres to the surface of the photosensitive drum 1 to be contaminated, the area of the surface potential at the time of light irradiation is Attenuation becomes small. Then, on the recorded image, a phenomenon occurs in which an image is not formed at a position where the image is originally formed, and a white area appears, which deteriorates the image quality.

When a jam of the recording paper P occurs,
During a certain period after the jammed recording sheet P is removed, the toner attached to the photosensitive drum 1 directly contacts the transfer roller 51. Therefore, in order to prevent the toner from adhering to the transfer roller 51 and to return the toner already adhering to the transfer roller 51 to the photosensitive drum 1 side, the power source 53 and the switch 54 are set as shown in FIG. For example, a voltage having the same polarity (negative polarity) as the toner is applied to the transfer roller 51 from the power supply 53 during the period in which the original transfer operation is not performed. However,
In the transfer roller 51 having the above-described structure, since the surface has considerable unevenness, the toner enters the unevenness, and the roller surface is not excellent in non-adhesiveness to the toner. Even if the voltage is applied, the toner cannot be completely removed from the transfer roller 51. For this reason, toner filming may occur on the transfer roller 51, the electric resistance value of the transfer roller 51 may increase, and the transfer efficiency may decrease.

The present invention has been made in consideration of the above circumstances, and its object is, firstly, to prevent contamination of the photosensitive drum, thereby extending the function of the photosensitive drum for a long period of time. An object of the present invention is to provide an electrophotographic recording device that can be maintained in good condition.

Secondly, to prevent contamination of the photosensitive drum,
As a result, the function of the photosensitive drum can be maintained satisfactorily for a long period of time, and the occurrence of toner filming on the transfer roller can be prevented, whereby the transfer efficiency can be maintained satisfactorily for a long period of time. An object of the present invention is to provide an electrophotographic recording device that can be used.

[0013]

In order to achieve the above-mentioned object, the present invention is an electrophotographic method using a photosensitive member such as a photosensitive drum formed by coating a negatively charged organic photosensitive material on the outermost layer. In an electrophotographic recording apparatus for recording an image, which has at least one elastic roller that comes into contact with the photoconductor, at least one outermost layer of the elastic rollers (for example, a charging roller or a transfer roller), A layer made of a fluorine-based resin having a low reactivity with the organic photosensitive material was formed.

[0014]

By taking such a measure, even if a substance that contaminates the photoconductor oozes out from the elastic material or the like for giving elasticity to the elastic roller, this substance is blocked by the layer made of the fluorine-based resin. Therefore, the fluorine-based resin does not adhere to the photoconductor, and the fluorine-based resin has low reactivity with the organic photosensitive material, so that the fluorine-based resin does not contaminate the photoconductor.

If a layer made of a fluorine-based resin is formed on the outermost periphery of the transfer roller, the adhesion of toner to the transfer roller is further prevented by the layer made of the fluorine-based resin, and toner filming on the transfer roller is performed. Does not occur.

[0016]

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

FIG. 1 is a view showing the arrangement of the essential parts of an electrophotographic recording apparatus according to this embodiment. The same parts as those in FIG. 3 are designated by the same reference numerals.

In the figure, reference numeral 1 denotes a photosensitive drum, which uses a negative charge type organic photosensitive material (OPC) as a photosensitive material.
The diameter of the photosensitive drum 1 is, for example, 30 mm, and the process speed is 32.5 mm / sec. Around the photosensitive drum 1, a charging device 7, an exposure device 3, a developing device 4, a transfer device 8 and a cleaning device 6 are provided along the peripheral surface thereof.

The charging device 7 is of a contact charging type and comprises a charging roller 71 as a contactor and a charging power source 22 for applying a voltage to the charging roller 71.
The charging roller 71 is in contact with the surface of the photosensitive drum 1 and is driven to rotate. When a voltage is applied from the charging power source 22, a discharge is generated between the charging roller 71 and the photosensitive drum 1, and the photosensitive drum 1 is charged. The charging roller 71 is formed by adhering an elastic material 21b to the shaft 21a and further winding a film 21c around the outer circumference of the elastic material 21b. The elastic material 21b is
It is a rubber material or a sponge material made of EPDM, silicon, urethane or the like, which is made conductive by dispersing a conductive filler such as carbon black or metal powder. The film 21c is made of a fluorine-based resin, for example, a mixture of polyvinylidene fluoride resin, fluorinated rubber, and a conductive agent. As the conductive agent, ether ester amide, carbon black, lithium chloride or the like is used.
The electric resistance value of the film 21c is set so that the electric resistance value of the charging roller 71 as a whole becomes about 1 × 10 ⁶ Ω · cm ² when a voltage of 1 KV is applied.
That is, the resistance of the charging roller 71 is controlled by the film 21c. The thickness of the film 21c is set in the range of 20 μm to 100 μm, and more preferably in the range of 40 μm to 80 μm in order to secure sufficient pressure resistance and prevent the roller hardness from increasing.

The exposure device 3 is composed of, for example, an LED head and irradiates the surface of the photosensitive drum 1 with light based on image data to form an electrostatic latent image corresponding to an image to be recorded.

The developing device 4 forms a toner image on the surface of the photosensitive drum 1 by depositing non-magnetic one-component toner on the surface of the photosensitive drum 1 in accordance with the electrostatic latent image formed by the exposing means 3. And the toner hopper 4
1, a supply roller 42, a developing roller 43, and a developing blade 44. The toner hopper 41 stores non-magnetic one-component toner. The supply roller 42 supplies the toner accumulated in the toner hopper to the developing roller 43. The developing roller 43 mainly carries and conveys the toner supplied by the supply roller 42, and brings the toner into contact with the photosensitive drum 1. The developing blade 44 thins the toner carried on the developing roller 43 and also triboelectrically charges the toner in a negative polarity. A supply bias of a predetermined voltage (for example, -300V) is applied to the supply roller 42 from a supply bias power source (not shown). A developing bias of a predetermined voltage (for example, -200V) is applied to the developing roller 43 from a developing bias power source (not shown). Further, the supply roller 42 and the developing roller 43 are rotated in the direction of the arrow in the drawing by a rotation driving device (not shown).

The transfer device 5 transfers the toner image formed on the surface of the photosensitive drum 1 by the developing device 4 onto the recording paper P, and the transfer roller 81 contacting the photosensitive drum 1 is provided.
Then, a transfer bias power source 52 for applying a transfer bias having a polarity (positive polarity) opposite to that of the toner on the photosensitive drum 1 to the transfer roller 81, and a voltage having the same polarity (negative polarity) as the toner are applied to the transfer roller 81. Power source 53 and transfer roller 8
It has a switch 54 for turning ON / OFF the bias application to No. 1 and selecting the transfer bias power source 52 and the power source 53. The transfer roller 81 includes a shaft 51a and an elastic member 5
1b is adhered, and a film 51c is wound around the outer periphery of the elastic material 51b. The elastic material 51b is a rubber material or a sponge material made of EPDM, silicon, urethane, or the like to which conductivity is imparted by dispersing a conductive filler such as carbon black or metal powder. Film 51c
Is made of a fluorine-based resin, and is made of a mixture of polyvinylidene fluoride resin, fluorinated rubber, and a conductive agent. As the conductive agent, ether ester amide, carbon black,
Alternatively, lithium chloride or the like is used. The electric resistance value of the film 51c is about 1 × 10 ⁹ when a voltage of 1 KV is applied as the electric resistance value of the transfer roller 81 as a whole.
It is set to be Ω · cm ² . That is, the resistance of the transfer roller 81 is controlled by the film 51c. The thickness of the film 51c is set in the range of 20 μm to 100 μm, and more preferably in the range of 40 μm to 80 μm in order to ensure sufficient pressure resistance and prevent the roller hardness from increasing.

The cleaning device 6 has a cleaning blade 61, a waste toner storage tank 62, and a waste toner roller 63. The cleaning device 6 is provided with a recording paper P.
The toner remaining on the photosensitive drum 1 without being completely transferred to the cleaning drum 61 is scraped off by the cleaning blade 61, conveyed to the waste toner storage tank 40 by the waste toner roller 63, and stored in the waste toner storage tank 40.

In the electrophotographic recording apparatus of the present embodiment having the above-described structure, contact charging, LED exposure, reversal development using a non-magnetic one-component toner, and contact transfer are conventionally known. An image is recorded on the recording paper P by the electrophotographic process.

Further, even if a cross-linking agent or an uncross-linked low molecular weight component exudes from the elastic material 21b of the charging roller 71 and the elastic material 51b of the transfer roller 81, these substances are blocked by the film 21c and the film 51c and exposed. It does not reach the surface of the drum 1. This prevents the OPC applied on the surface of the photosensitive drum 1 from being contaminated,
An electrostatic latent image faithful to the image to be recorded can be formed on the photosensitive drum 1 by exposure by the exposure device 3, and high quality recording can be performed. The fluorine-based resin forming the film 21c and the film 51c has low reactivity with the negative charging type OPC, and the film 21c and the film 51c do not contaminate the photosensitive drum 1.

Further, as can be seen from the charging sequence of the polymer shown in FIG. 2, the fluorine-based polymer is more likely to be negatively charged than other polymers such as urethane and silicon, so that the photosensitive drum can be easily charged. It is negatively charged by friction with 1.
Has a strong repulsive force against toner. Further, the film 51c having the above-described structure has a surface roughness of 1 μm or less even at the maximum value, which is very small compared to the toner particle size (average 10 μm)
The toner does not enter the irregularities on the surface of the film 51c. As a result, the transfer roller 81 exhibits a very excellent releasing property with respect to the toner, and the toner is hard to adhere. Therefore, toner filming does not occur on the transfer roller 81, the electric resistance value thereof is maintained constant, and good transfer can be performed.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the layer made of the fluorine-based resin is formed by winding the film 21c and the film 51c, respectively. However, without using the film, for example, the fluorine-based resin is applied to form the layer made of the fluorine-based resin. You may form.

Further, in the above-described embodiment, the charging roller 71 and the transfer roller 81 are formed with a layer made of a fluorine-based resin. However, if there is another roller that comes into contact with the photosensitive drum 1, the roller is made of a fluorine-based resin. You may form the layer which consists of resins.

In the above embodiment, the electric resistance values of the charging roller 71 and the transfer roller 81 are controlled by the electric resistance values of the film 21c and the film 51c, but the electric resistance values of the film 21c and the film 51c are taken into consideration. The charging roller 71 and the transfer roller 81 are controlled by controlling the electric resistance values of the elastic material 21b and the elastic material 51b.
You may control the electric resistance value of.

Besides, various modifications can be made without departing from the scope of the present invention.

[0031]

According to the first aspect of the present invention, an image is recorded by an electrophotographic method using a photosensitive member such as a photosensitive drum formed by coating a negatively chargeable organic photosensitive material on the outermost layer. , At least one elastic roller abutting the photoconductor
In an electrophotographic recording apparatus having one, since at least one outermost layer of the elastic roller is formed with a layer made of a fluorine-based resin having low reactivity with the organic photosensitive material, contamination of the photosensitive drum is prevented, As a result, the electrophotographic recording apparatus can maintain the function of the photosensitive drum satisfactorily for a long period of time.

According to the second aspect of the invention, since the outermost layer of the transfer roller of the elastic rollers is formed of a fluorine resin having a low reactivity with the organic photosensitive material, the photosensitive drum is contaminated. To prevent the occurrence of toner filming on the transfer roller, while maintaining good function of the photosensitive drum for a long period of time.
As a result, the electrophotographic recording apparatus can maintain the transfer efficiency excellently for a long period of time.

[Brief description of drawings]

FIG. 1 is a diagram showing a main configuration of an electrophotographic recording apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a charging sequence of a polymer.

FIG. 3 is a diagram showing a configuration example of a conventional electrophotographic recording apparatus.

FIG. 4 is a diagram illustrating the principle of a reversal development method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum 3 ... Exposure device 4 ... Developing device 6 ... Cleaning device 7 ... Charging device 71 ... Charging roller 21a ... Shaft 21b ... Elastic material 21c ... Film 8 ... Transfer device 81 ... Transfer roller 51a ... Shaft 51b ... Elastic material 51c …the film

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Claims (2)

[Claims] 1. An image is recorded by an electrophotographic method using a photoconductor formed by applying a negatively chargeable organic photosensitive material to the outermost layer, and at least one elastic roller is in contact with the photoconductor. In the electrophotographic recording apparatus having the electrophotography, at least one of the elastic rollers has a layer made of a fluorine-based resin having a low reactivity with the organic photosensitive material formed on the outermost layer. Recording device. 2. The electronic roller according to claim 1, wherein the elastic roller is a transfer roller for transferring the toner attached to the photoconductor to a recording paper inserted between the photoconductor and the photoconductor. Photo recording device.