JPH1063090A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of obtaining an image of high quality by preventing the chemical change and filming of a photoreceptor caused by ozone and NOx . SOLUTION: The difference in circumferential speed between the photoreceptor 1 and a developing roller 5, in nondevelopment is made larger than that in development and the circumferential speed of the developing roller 5 in the nondevelopment is lower than that in the development. When voltages applied to the developing roller 5 and a toner supplying roller 6, in the nondevelopment are defined as VB and VSR respectively, the relation of |VSR|<|VB| is satisfied, where the VB has the same polarity as that of the charge of toner 10 or the opposite polarity relation of the VSR to the polarity of the charge of the toner 10 is satisfied. Or the relation of |VSR|>|VB| is satisfied, where the VB has the polarity opposite to that of the charge of the toner 10 or the VSR has the polarity opposite to that of the charge of the toner 10, where VB=0. Thus, the shortening of the life of a developing unit is prevented so that the chemical change and filming of the photoreceptor 1 caused by ozone and NOx can be prevented as well.

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 using a cleanerless system which performs cleaning simultaneously with development in an electrophotographic apparatus or an electrostatic recording apparatus.

[0002]

2. Description of the Related Art Electrophotographic apparatuses which use dry toner have been dominant in the past, and have been remarkably developed for practical use as image forming apparatuses such as many copying machines, laser printers, and plain paper facsimile machines. The electrophotographic apparatus is an apparatus to which an electrophotographic process technology is applied, and visualizes an electrostatic latent image formed on a photoreceptor with toner particles.

In this image forming apparatus, recently, in order to reduce the size and cost of the apparatus and protect the environment, a cleaning device for removing toner remaining on the photoreceptor after transfer is abolished, and the image forming apparatus remains at the same time as development. An apparatus using a so-called cleanerless system for cleaning the toner is becoming widespread.

Hereinafter, the configuration and operation of a conventional image forming apparatus will be described with reference to the drawings. FIG. 1 is a configuration diagram of a conventional image forming apparatus using a cleanerless system.
In FIG. 1, reference numeral 1 denotes a photoreceptor, which is made of a metal drum such as aluminum as a base material, and has a photoreceptor layer such as selenium (Se) or an organic photoconductor (hereinafter, referred to as OPC) formed in a thin film on the outer peripheral surface thereof. It is formed by coating. The charger 2 disposed close to the photoreceptor 1, which is an electrostatic latent image carrier, includes a charging wire 2a such as a tungsten wire, a metal shield plate 2b, and a grid plate 2c. The charging line 2a causes corona discharge to uniformly charge the photoconductor 1 via the grid plate 2c. The exposure light beam 4 emitted from the exposure optical system 3 is obtained by subjecting an image signal to light intensity modulation or pulse width modulation by a laser driving circuit (not shown), and forms an electrostatic latent image on the photoconductor 1.

Reference numeral 6 denotes a toner supply roller for supplying the toner 10 stirred and conveyed by a toner stirring member 11 rotatably supported at both ends to a developing hopper 9 to the surface of a developing roller 5 as a toner carrier. Supply bias power supply 2
5, a toner supply bias voltage is applied. The developing roller 5 and the toner supply roller 6 are made of a metal such as stainless steel as a base material, and elastic members such as urethane and silicon are formed in a layer on the outer peripheral surface thereof, and are rotatably supported at both ends of the developing hopper 9. 5a and 6a are shafts.

The toner 10 supplied by the toner supply roller 6 is frictionally charged by the toner regulating blade 7 to form a thin layer on the outer peripheral surface of the developing roller 5.
The developing roller 5 is in contact with the photoreceptor 1, and is supplied with a bias voltage applied from a developing bias power supply 12.
The toner 10 is transferred and adhered to the portion where the above electrostatic latent image is formed to visualize the electrostatic latent image, and at the same time, the residual toner after transfer is collected in the developing device.

The toner regulating blade 7 comprises a metal spring plate member 7a and a toner regulating member 7b which comes into contact with the developing roller 5. The toner regulating member 7b is provided with an elastic member such as silicon or urethane at one end of the metal spring plate member 7a. They are integrally formed. Reference numeral 8 denotes a blade holder for fixing the toner regulating blade 7, which is attached by screwing. The toner stirring member 11 draws a circular trajectory with the rotation of the toner supply roller 6, prevents aggregation of the toner 10 contained in the developing hopper 9, and conveys the toner 10 to the toner supply roller 6.

[0008] Paper 1 stored in paper cassette 14
Reference numeral 5 denotes a paper feed roller 16 having a half-moon shape from the paper cassette 14.
Is fed out to the transport roller 17 one by one. The sheet 15 which is the recording sheet sent out is transported by the transport roller 17 in the direction indicated by the arrow A. 18 is paper 1
This is a registration roller for temporarily stopping the paper 15 for standby so that the toner image 5 and the toner image formed on the photoreceptor 1 coincide with each other. The transfer roller 20 is made of a metal such as stainless steel as a base material and has an elastic member formed in a layer on the outer peripheral surface thereof. When the toner image reaches the contact portion between the transfer roller 20 and the photosensitive member 1 with the rotation of the photosensitive member 1, the paper 15 also reaches the contact portion in synchronization with the toner image. By applying a high voltage from the transfer bias power supply 24 to the metal shaft 20 a, a charge having a polarity opposite to that of the toner 10 is applied to the back surface of the sheet 15, and the toner image on the photoconductor 1 is transferred onto the sheet 15. Next, the sheet 15 is sent to the left in the drawing, and the toner image transferred onto the sheet 15 is transferred to the heat roller 22 by a fixing device 21 including a heat roller 22 having a heat source therein and a pressure roller 23. The fixing is performed by pressurization and heat with the pinching rotation of the pressure roller 23. On the other hand, the photoreceptor 1 after the toner image has been transferred onto the paper 15 is irradiated with light by the static eliminator 13 to eliminate the charge, and prepares for the next process.

An image forming apparatus using such a cleanerless system is advantageous in terms of miniaturization, cost reduction and environmental protection of the apparatus.

[0010]

In the case of the image forming apparatus having the above-mentioned structure, there is generally no cleaning blade in contact with the photosensitive member 1 for removing residual toner after transfer. surface hardly wear of a problem that primarily charged and image deterioration due to filming of the chemical changes and the photosensitive member 1 surface photoreceptor 1 due to ozone and NO _X generated in the transfer means is likely to occur Had a point.

As means for solving this problem, there is a means for increasing the peripheral speed of the developing roller 5 during non-development and reducing the amount of toner adhered on the developing roller. However, when the peripheral speed of the developing roller 5 is increased, stress on the developing roller 5, the toner 10, and the like increases, which causes a problem that the life of the developing unit is shortened.

The present invention solves the above-mentioned conventional problems, and provides an image forming apparatus using a cleanerless system capable of forming a high-quality image over time without a reduction in the life of a developing unit. The purpose is to do.

[0013]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a developing device in which the peripheral speed difference between the photosensitive member and the developing roller during non-development is larger than during developing, and the peripheral speed of the developing roller is reduced during developing. Is less than the peripheral speed of an image forming apparatus using a cleanerless system.
Chemical changes of the photoconductor due to _X or the like and filming of the photoconductor surface can be prevented.

If the developing bias voltage applied to the developing roller during non-development is V _B and the toner supply bias voltage applied to the toner supplying roller during non-developing is V _SR , V _B
Is the same polarity as the charge polarity of the toner, and | V _SR | <| V
_B | or V _SR is obtained by so as to satisfy the opposite polarity related to the charge polarity of the toner, the photosensitive such as by ozone and NO _X without causing reduction in the life of the developing unit in an image forming apparatus using the cleanerless method Chemical change of the body and filming of the photoreceptor surface can be prevented.

If the developing bias voltage applied to the developing roller during non-development is V _B and the toner supply bias voltage applied to the toner supplying roller during non-developing is V _SR , V _B
Is the polarity opposite to the charging polarity of the toner, and | V _SR |> | V
_B | which was to satisfy the relation, fill ozone and NO _X, such as by chemical transformation or a photosensitive surface of the photoreceptor without causing the reduction of the service life of the developing unit in an image forming apparatus using the cleanerless method It is possible to prevent ming.

If the developing bias voltage applied to the developing roller during non-development is V _B and the toner supply bias voltage applied to the toner supplying roller during non-developing is V _SR , V _B
= 0, and _VSR is the polarity opposite to the charging polarity of the toner. In an image forming apparatus using a cleanerless system, ozone and N
O _X filming chemical change or a photosensitive surface of the photoreceptor due can be prevented.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, there is provided a charging unit for charging a photoreceptor, an exposure unit for forming an electrostatic latent image on the photoreceptor, and an electrostatic unit formed on the photoreceptor. A developing roller that forms a toner layer on the surface to form a latent image into a toner image and a toner supply roller that is arranged in contact with the developing roller to supply toner and a toner regulating blade that regulates toner on the developing roller and forms a thin layer and develops Developing means having means for applying a developing bias voltage to the roller, means for applying a toner supply bias voltage to the toner supply roller, and transfer means for transferring a toner image formed on the photoreceptor to a recording medium An image forming apparatus for cleaning toner remaining on a photoreceptor after transfer by a transfer unit at the same time as developing by a developing unit. Ri is large, and it is the peripheral speed of the developing roller which is made smaller than at the time of development, the photosensitive member surface photoconductor chemical due likely ozone and NO _X worn without increasing the stress on the developing roller and toner It is possible to prevent the film from being changed or filming on the surface of the photoreceptor.

According to a second aspect of the present invention, if the developing bias voltage applied to the developing roller during non-development is V _B and the toner supply bias voltage applied to the toner supplying roller during non-developing is V _SR , V _B The same polarity as the charging polarity of the toner, and | V _SR | <| V _B | or V _SR satisfies the relationship of the polarity opposite to the charging polarity of the toner. Have.

According to a third aspect of the present invention, if the developing bias voltage applied to the developing roller during non-development is V _B and the toner supply bias voltage applied to the toner supplying roller during non-developing is V _SR , V _B It has a polarity opposite to the charging polarity and satisfies the relationship of | V _SR |> | V _B |, and has the same effect as the first aspect.

According to a fourth aspect of the present invention, if the developing bias voltage applied to the developing roller during non-development is V _B and the toner supply bias voltage applied to the toner supplying roller during non-developing is V _SR , V _B = 0 _VSR has a polarity opposite to the charging polarity of the toner, and has the same function as that of the first aspect.

Hereinafter, embodiments of the present invention will be described. Here, the basic configuration of the image forming apparatus is the same as that of the conventional one shown in FIG. The rotation directions of the photoconductor 1, the developing roller 5, and the toner supply roller 6 are in the directions of the arrows shown in FIG. 1, and the respective contact portions are in frictional contact.

The photosensitive member 1 is a negative charging type OPC, and is uniformly charged to -700 V by the charger 2.

The developing roller 5 has a resistance value of 10 ⁶ Ω in a single-layer configuration in which a metal shaft 5a is used as a base material and silicon rubber as a conductive elastic member is formed on an outer peripheral surface thereof. A developing bias power supply 12, which is a constant voltage power supply, is connected to the shaft 5a of the developing roller 5. This developing roller 5
The rubber hardness is preferably in the range of 30 to 60 degrees, and the surface roughness is preferably 7 μmRz or less, since the higher the surface smoothness, the more uniform the formation of a thin toner layer. In the present embodiment, the developing roller 5 has a rubber hardness of 40 degrees and a surface roughness of 3 μmRz.

The toner supply roller 6 has a conductive shaft formed around a metal shaft 6a and has a resistance value of 10%.
^The toner supply bias power supply 25 which is a constant voltage power supply is connected to the shaft 6a. The toner supply roller 6 has a function of supplying the toner 10 supplied from the development hopper 9 to the development roller 5 and scraping off the toner 10 remaining on the development roller 5 without being developed. The nip width between the toner supply roller 6 and the developing roller 5 is 2 mm.

The toner regulating blade 7 includes a stainless steel plate,
A resilient metal spring plate member 7a such as a phosphor bronze plate, and urethane rubber having a rubber hardness of 60 degrees, which is an elastic member, is integrally formed at one end as a toner regulating member 7b, and is screwed to the blade holder 8. . Toner regulating member 7
“b” presses the developing roller 5 at a linear pressure of 80 g / cm to form a 0.5 mg / cm ² toner layer on the surface of the developing roller 5. In the non-magnetic one-component contact developing system as in this embodiment, the toner layer on the developing roller 5 is 0.3 to 0.6.
The range of mg / cm ² is preferred.

The toner 10 is a non-magnetic one-component toner, and is made of a polyester resin in which carbon, wax, a charge control agent and the like are uniformly dispersed, and a negatively chargeable toner is used.

The transfer roller 20 includes a metal shaft 20.
a having a conductive foam formed around it and having a resistance value of 10 ⁷
Ω, and a transfer bias power supply 24 is connected to the shaft 20a. The transfer bias power supply 24 is a 4 μA constant current power supply.

The process speed was 76 mm / sec, the peripheral speed of the developing roller 5 during development was 106 mm / sec, and the peripheral speed of the toner supply roller 6 was 75 mm / sec.

The following printing operation was performed on the image forming apparatus using the cleanerless system configured as described above. First, the photosensitive member 1 is uniformly charged to -700 V, and then exposed by the exposure optical system 3 to attenuate the surface potential of the exposed photosensitive member 1 to -100 V. Forming a toner image on body 1,
A toner image was transferred by applying a current of 4 μA from the transfer roller 20 to the sheet 15 and a toner image was obtained on the sheet 15 through a fixing step generally known as an electrophotographic process.

[0030] Since the charging potential of over time ozone and NO _X as by the filming of chemical changes and the photosensitive member 1 surface of the photosensitive member 1 is generated photoreceptor 1 tends to decrease, non-development time -300V developing bias V _B of, 0V,
And 300 V, the peripheral velocity v _d of 26 mm / sec of the developing roller 5 during the non-development, 46mm / sec, 106mm / s
Table 1 shows the results of measuring the charging potential of the photoconductor 1 after printing 500 sheets by the above printing operation while changing the toner supply bias V _SR during non-development.

[0031]

[Table 1]

As is evident from Table 1, the undeveloped state
The peripheral speed difference between the photosensitive member 1 and the developing roller 5 is larger than that during the development.
And the peripheral speed of the developing roller 5 is smaller than that during development.
And a developing bias voltage applied to the developing roller 5 during non-development.
Pressure V_BTo be applied to the toner supply roller 6 during non-development.
V supply voltage_SRThen V_BTo toner 1
| V as the same polarity as the charging polarity of 0_SR| <| V_B| Or
V_SRSatisfies the relationship of the polarity opposite to the charging polarity of the toner 10.
Or V_BWith the polarity opposite to the charging polarity of the toner 10
Then | V_SR|> | V_B|
V_B= 0 as V _SRIs the polarity opposite to the charging polarity of the toner 10.
Ozone and NO_XPhotoreceptor 1
Prevents chemical change of surface and filming of photoreceptor 1 surface
And the photosensitivity hardly changes from the initial charge value of -700V
The charged potential of the body 1 was obtained.

Further, in this case, no change in the surface of the developing roller 5 was observed, and there was no change in the image quality. Therefore, it is considered that the stress on the toner 10 did not increase, and the life of the developing unit was not reduced. Conceivable.

In the present embodiment, a negatively charged photosensitive member,
Although a system using negatively charged toner was used, a positively charged photoconductor and a positively charged toner can be similarly applied. Further, although urethane rubber which is an elastic member is used as the toner regulating member 7b, various rubber materials such as silicon rubber, fluorine rubber, acrylic rubber, butadiene rubber, EPDM rubber, etc., various resin materials which are rigid members, and A metal member may be used. However, in order to prevent a change in the amount of toner adhered on the developing roller 5 with time, it is preferable that the wear resistance is excellent. Further, the developing roller 5 need not be limited to an elastic roller, but may be a metal roller or a resin roller.

[0035]

As described above, according to the present invention, during non-development, the peripheral speed difference between the photosensitive member and the developing roller is made larger than during developing, and the peripheral speed of the developing roller is made smaller than during developing.
By generating an electric field in which the toner moves to the toner supply roller side and the toner adhesion amount on the developing roller is reduced,
High quality images prevent filming of chemical changes and the photosensitive member surface, such as by a photoreceptor ozone and NO _X without increasing the stress on the developing roller and the toner can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a conventional image forming apparatus using a cleanerless system.

[Explanation of symbols]

 Reference Signs List 1 photoconductor 5 developing roller 6 toner supply roller 10 toner 12 developing bias power supply 25 toner supply bias power supply

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kazuhiko Noda 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] A charging means for charging a photoconductor, an exposure means for forming an electrostatic latent image on the photoconductor, and a toner layer for forming a toner image on the electrostatic latent image formed on the photoconductor. A developing roller, a toner supply roller disposed in contact with the developing roller and supplying toner, a toner regulating blade for regulating the toner on the developing roller to form a thin layer, and a means for applying a developing bias voltage to the developing roller And a transfer unit for transferring a toner image formed on the photoreceptor to a recording medium, wherein the transfer unit transfers the toner image formed on the photoconductor to a recording medium. An image forming apparatus which cleans toner remaining on the photoconductor at the same time as the development by the developing unit, wherein the peripheral speed of the photoconductor and the developing roller during non-development An image forming apparatus comprising greater than at the time of development, and the peripheral speed of the developing roller less than that during the development that the. 2. A developing bias voltage applied to the developing roller during non-development is represented by V _B , and a toner supply bias voltage applied to the toner supplying roller during non-developing is represented by V _SR.
B is the same polarity as the charge polarity of the toner, and | V _SR | <|
2. The image forming apparatus according to claim 1, wherein V _B | and V _SR satisfy a relationship of a polarity opposite to the charging polarity of the toner. 3. A developing bias voltage applied to the developing roller during non-development is represented by V _B , and a toner supply bias voltage applied to the toner supplying roller during non-developing is represented by V _SR.
B is the polarity opposite to the charging polarity of the toner, and | V _SR |> |
2. The image forming apparatus according to claim 1, wherein a relationship of V _B | is satisfied. 4. When a developing bias voltage applied to the developing roller during non-developing is V _B and a toner supplying bias voltage applied to the toner supplying roller during non-developing is V _SR ,
_2. The image forming apparatus according to claim 1, wherein _B = 0 and _VSR has a polarity opposite to the charging polarity of the toner.