JPH1049024A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device for excellently forming an image by removing dust generated from a recording medium. SOLUTION: The device is constituted so as to make a toner image carried on the surface of a photoreceptor 1 transferable to the recording medium by a transfer means 5. In such a case, the device is constituted so that a conductive cleaning means 6a coming into contact with the surface of the photoreceptor is arranged on the downstream side of the transfer means 5, a voltage capable of reversing its polarity can be applied to the conductive cleaning means 6a and in a transfer and a nontransfer by the transfer means 5, the applied voltage is reversed in the polarity, to be applied to the conductive cleaning means 6a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer, a copying machine,
The present invention relates to an image forming apparatus such as a facsimile, and more particularly, to an image forming apparatus provided with a conductive cleaning unit that comes into contact with the surface of a photoconductor downstream of a transfer unit.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic apparatus based on the so-called Carlson process, which is a kind of image forming apparatus, is well-known. It is necessary to apply a high voltage of 8 KV or more to the wire, and as a result, ozone and nitrogen oxides and ammonium salts, which are discharge products thereof, are generated, and these are adsorbed on the surface of the photoreceptor, so that image flow is likely to occur.

In order to solve such a drawback, a roller configured to contact a conductive roller on a photosensitive drum and apply a DC voltage to the conductive roller to perform contact charging of the photosensitive drum in a dark place. Although there is a charging method, even in this charging method, since there is a minute wedge-shaped gap between the photosensitive drum and the charging roller, a slight discharge phenomenon occurs in that portion, and the generation of ozone is recognized. However, the disadvantages described above cannot always be eliminated.

On the other hand, in recent years, there has been a photosensitive drum used in an electrophotographic apparatus which uses an a-Si drum in order to improve durability and achieve free maintenance.
-Si has a higher hygroscopicity than an organic semiconductor, and therefore, the image flow is likely to occur on the a-Si drum. Therefore, a sheet heater or other heating element is disposed on the back side of the photosensitive drum. By heating the photosensitive drum, the occurrence of the image deletion is prevented.

[0005] However, providing a heater not only requires a heat control means and the like, but also complicates the configuration,
In particular, if a heater is used in copiers and printers that are smaller and more personalized, the system becomes complicated. In addition, a certain time is required for raising the temperature of the heater, and the time from when the power is turned on to when printing is performed (warm-up time) is long, which requires power consumption. Also,
When the photoconductor is heated, the temperature is raised to a temperature close to the TG temperature (glass transition temperature) of the toner, so that the toner adheres to the surface of the photoconductor. Various problems occur.

Further, even in a state in which image deletion does not occur, in this type of electrophotographic apparatus, toner adheres to a developing area of an electrostatic latent image formed on a photosensitive member in a developing step, and a toner adheres to a non-developing area. In order to prevent adhesion, the photosensitive member surface potential is set to 400 V or more in the charging step, and the difference between the high potential portions of the electrostatic latent image formed in the exposure step is set to 400 V.
As described above, the developing potential was required to be 200 V or more. Therefore, a photoconductive material having a charging ability of 400 V or more is required for the photoreceptor, and there are great restrictions on material selection and film thickness setting.

Further, a-Si tends to cause a so-called “fogging” phenomenon in which toner adheres to a white background. This is a phenomenon in which the toner in the apparatus adheres to the surface of the photoreceptor due to an image force or the like. The image power of the toner is greatly affected by the relative permittivity of the photosensitive layer, and the higher the relative permittivity, the higher the image power. This relative dielectric constant is usually 3 to 3 for an organic photoreceptor.
Since it is 3.5, and a-Si is as large as about 10 to 12, a-fogging phenomenon easily occurs in a-Si.

Conventionally, a pulverized toner has been used. This pulverized toner is obtained by cooling a kneaded material obtained by mixing small particles such as a resin, a colorant and a charge control agent, and then coarsely pulverized by a hammer mill, a cutter mill or the like, and further jet-milled. 8 to 1 depending on the size
It is made by finely pulverizing it to about 5 μm. Although it is relatively easy to make, it is made into an irregular shape with irregularities, and the charge tends to concentrate on the protrusions, and the surface of the photoreceptor may come into contact with a plurality of protrusions for one particle. In some cases, the image power increases.

Under such circumstances, the applicant of the present invention prior to the present application used an a-Si drum, and in particular, uniformly charged the photosensitive member including a discharge phenomenon, such as a corona discharger, a charging roller, and a charging brush. The purpose of the present invention is to provide an electrophotographic apparatus capable of forming a clear image without causing an image flow and a 'fogging' phenomenon even in an electrophotographic apparatus which has performed the above, and a photoconductive layer and a surface layer are laminated and coated on a substrate. The thickness of the surface layer of the electrophotographic photoreceptor is formed of an a-Si layer having a thickness of 25 μm or less, and the surface potential of the photoreceptor is set to approximately 400 V or less. setting the developing roller along with make rubbing was, the set the volume resistivity of the developing roller below 3 × 10 ⁷ Ωcm, the developing roller, before while forming a thin layer of toner particles created by a polymerization method The electrophotographic apparatus configured to perform development of the latent image on the photoreceptor are filed.

[0010]

In the apparatus according to the above-mentioned application, the developing means also serves as the cleaning means.
Cleaning while shaving the photoconductor surface to some extent,
At the same time, development is possible to prevent the image deletion phenomenon under a special environment. However, if paper is used for the recording medium transferred from the photoconductor and the above-described apparatus is used for a long time, when the paper is transferred from the photoconductor to the recording paper, a small portion of the paper peels off and becomes garbage, When mixed in the developer, dust adheres to the image together with the development, and a good image cannot be formed. The present invention has been made in view of the above circumstances, and has as its object to provide an image forming apparatus that removes dust generated from a recording medium and forms a good image. Another object of the present invention is to provide an image forming apparatus that eliminates fogging and removes dust generated from a recording medium to form a good image.

[0011]

According to the present invention, there is provided an image forming apparatus configured to be capable of transferring a toner image carried on the surface of a photoreceptor to a recording medium by a transfer means. A conductive cleaning unit that is in contact with the surface of the photoreceptor is provided, and a voltage capable of reversing the polarity is applied to the conductive cleaning unit, and the conductive cleaning unit is applied to the conductive cleaning unit during transfer and non-transfer of the transfer unit. The voltage was inverted and applied.

The present invention relates to a developing roller 40 in a developing container 41.
As a result, the residual toner 49 (FIG. 2) is removed from the photoconductor surface. Further, a conductive cleaning means (roller) 6a which comes into contact with the surface of the photoreceptor (photoreceptor drum) 1 is provided downstream of the transfer means 5, so that the surface of the photoreceptor 1 in FIG. The toner image is transferred by a transfer means such as a transfer roller and the like, not shown, in which the recording paper 9 is inserted between the photoreceptor 1 and the transfer roller 5 and a transfer voltage is applied to the transfer roller 5.

At this time, the recording medium 9 generates paper dust, but a cleaning means 6 is provided downstream of the transfer roller 5, and the conductive cleaning roller 6a is switched between a transfer time and a non-transfer time to switch the reverse voltage. Is applied, the conductive cleaning roller 6a absorbs the paper dust together with the toner during the transfer, so that a small amount of residual toner is transferred to the developing container 41 side. It is substantially eliminated before reaching the container 41, and good image formation can be performed.

During non-transfer, since the polarity of the voltage applied to the conductive cleaning roller 6a is reversed, residual toner is discharged from the conductive cleaning roller 6a to the surface of the photosensitive member 1, but paper dust is removed from the conductive cleaning roller 6a.
And the toner with very little paper dust adheres again to the photoreceptor surface and is transferred to the developing container 41.

The residual toner travels twice from the photosensitive member to the conductive cleaning roller and from the conductive cleaning roller to the photosensitive member twice, and a large lump of the residual toner is pulverized into small pieces. The toner is separated from the toner, the rate of being restrained by the conductive cleaning roller is increased, and the toner can be prevented from collecting on the conductive cleaning roller and overflowing in the cleaning unit 6.

The conductive cleaning roller 6a is configured to apply a voltage of the opposite polarity during transfer and during non-transfer. However, the condition during transfer is that the transfer voltage is applied to the transfer roller 5. In other words, non-transfer time means a state in which no transfer voltage is applied. Since the voltage of the opposite polarity is applied to the conductive cleaning roller 6a at the time of transfer and at the time of non-transfer, the potential of the conductive cleaning roller 6a is inverted at the time of non-transfer during transfer to the recording paper 9. And the potential difference between the two becomes large at the time of transfer, so that the transfer to the recording paper is not affected.

It is also effective in the present invention to provide a forward peripheral speed difference between the conductive cleaning means and the photosensitive member, and preferably to make the peripheral speed of the conductive cleaning means higher than that of the photosensitive member. It is.

By making the peripheral speed of the conductive cleaning roller greater than the peripheral speed of the photosensitive member, the contact point on the surface of the photosensitive member can be reduced by making the peripheral speed of the conductive cleaning roller and the photosensitive member equal to each other. , Successively contacting the new contact point of the conductive cleaning roller, and coming into contact with the wide surface of the conductive cleaning roller, thereby increasing the absorption efficiency of the residual toner, and as a result, the removal efficiency of removing the paper dust is improved. .

Further, the conductive cleaning means may be formed by a sponge so as to be able to catch the peeling powder from the recording medium by the difference in peripheral speed, or a toner produced by a polymerization method may be used. This is an effective means of the present invention.

The sponge has countless large and small holes formed on its surface, and countless projections are also formed on the inner peripheral surface of the hole.
The paper powder is restrained in the hole or the inner peripheral surface of the hole. The paper dust is smaller than the polymerized toner, and the shape of the paper dust is not spherical compared to the polymerized toner, it is a complicated shape, and there are countless thread-like whiskers. The rate of being restrained by sponge is much higher. Therefore, even if the toner is returned to the photoreceptor surface during non-transfer, it is extremely small that the paper dust adheres to the toner and is returned.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be illustratively described in detail with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples. Not just.

FIG. 1 shows an embodiment of an image forming apparatus having a paper dust removing means to which the present invention is applied, and an a-Si photosensitive drum (photosensitive body) 1 rotating clockwise in FIG.
An optical system composed of an exposure LED head 2 and a selfoc lens 3, a developing unit 4, a transfer roller 5, a cleaning member (means) 6, a static elimination lamp 7, and a charging unit 8 are arranged along the rotation direction.

Next, each component will be described. The photoconductor drum 1 is formed by laminating a photoconductive layer 1b and a surface layer 1c on a conductive support 1a as shown in A in an enlarged manner, and the conductive support 1a and the photoconductive layer 1 are formed.
b, a carrier injection blocking layer 1e and a photoconductive layer 1b
A transition layer 1f is interposed between the first layer and the surface layer 1c. The support 1a is generally made of an aluminum cylinder, but is made of a metal material such as SUS, Ti, Ni, Au, Ag, etc., an inorganic material such as glass having a conductive film adhered on the surface, or a transparent material such as epoxy. In this embodiment, the thickness is set to 3 mm and the outer diameter is set to 30 mm.
An aluminum cylinder having a length of 254 mm in the axial direction is used.

The carrier injection blocking layer 1e is a photoconductive layer 1
Various materials are used depending on the material of b. When an a-Si-based material is used for the photoconductive layer 1b, it is preferable to use the a-Si-based carrier injection blocking layer 1e. The total thickness of the photoconductive layer 1b is preferably about 3 to 50 μm in order to ensure necessary charging and dielectric strength, absorb exposed light, suppress the above-described residual potential, and the like.

The hardness of the surface layer 1c is set so as to gradually increase as it goes from the outermost surface side to the back side on the photoconductive layer 1b side. In order to provide a gradient of the hardness as described above (a gradient in which the hardness gradually increases from the outermost side toward the back side of the photoconductive layer 1b), for example, the surface layer 1c is decomposed by glow discharge. In the case of film formation by the method,
Gradually increasing the ratio of the C-containing gas to the Si-containing gas in the source gas over time; gradually increasing the gas pressure during film formation; gradually decreasing the dilution ratio of the source gas with hydrogen gas; Is gradually reduced, and the substrate temperature of the aluminum cylindrical drum is gradually lowered.

A transition layer 1f in which the C content in a-SiC: H is smaller than the C content in the surface layer 1c may be provided between the photoconductive layer 1b and the surface layer 1c. Further, the C content of the transition layer 1f may be changed in the layer to have a gradient of the content. By providing such a transition layer 1f, the traveling of the photocarriers generated in the photoconductive layer 1b becomes smooth, the photosensitivity is high, the residual potential is low, and the image characteristics are good.

The surface layer 1c may have a two-layer structure instead of a single-layer structure. For example, as shown in B in an enlarged manner,
The surface layer 1c, allowed comprising a second layer region 1c ₂ of the first layer region 1c ₁ and the free surface side of the photoconductive layer 1b side, the second layer region 1c ₂ the elemental ratio composition formula (a-Si _{1- x} C _x : H), x is set to 0.95 ≦ x <1, the dynamic indentation hardness is set to 50 to 200 kgf / mm ² , and the thickness is set to 800 to 3000 (angstrom). large first layer hardness region 1c ₁ of the inner side of the second layer region 1c _2, specifically a hardness enough not to wear abrasive such as a polishing agent, 300 Kgf / mm dynamic indentation hardness ^It is better to use ² or more. Thus, the independent polishing means for each replication process is performed to remove such discharge products adsorbed to the second layer region 1c ₂ moderately polished surface of the second layer region, and the surface is smoothed its polished with been out is prevented by the first layer region 1c ₁ on the back side, thereby is achieved a more longer life.

A head array having an exposure wavelength of 685 nm is used as the exposure LED head 2, and the head array is configured so as to perform dynamic exposure to divide 64 bits × 40 times for each scanning line.

The developing unit 4 comprises a developing container 40 containing a non-magnetic one-component toner, a developing roller 40 comprising an elastic body 42 made of an elastic material such as urethane rubber, and a toner layer thickness to the roller 40. Regulating developing blade 17
And a supply roller 45 for supplying toner to the developing roller 40. The developing roller 40, the supply roller 45,
The developing blade 17 and the like have a DC developing bias power source E1 (not shown) that can be set arbitrarily between 50 and 500 V, for example.
(350 V), E2 (350 V), and E3 (120 V) to perform development.

In the developing unit 4, as shown in FIG. 2, a new toner 50 is supplied to the developing roller 40 by a supply roller 45 which rotates counterclockwise, and the developing blade 17 for regulating the toner layer thickness. , is regulated by the toner layer thickness ^{0.3mg / cm 2 ~0.9mg / cm 2} , it is supplied to the photosensitive member 1.

On the other hand, the residual toner not transferred to the recording paper 9 is restrained at the time of transfer by the cleaning means 6, but it should be considered that some toner is transferred to the developing container 41 as the residual toner 49. The residual toner 49 comes into contact with the elastic body 42 of the developing roller 40 again.
Since the peripheral speed of the photoconductor 1 is higher than that of the photoconductor 1, the residual toner 49 is reduced by the
And new toner 4
8 develops the latent image on the surface of the photoconductor 1.

As indicated by reference numeral 51, the developing container 41
The residual toner 52 adhered to the developing roller 40 without dropping to the lower portion of the developing roller 40 is transferred to the developing roller 4 in the nip area where the developing roller 40 and the supply roller 45 affect each other.
By the supply roller 45 rotating in the direction opposite to the direction 2, the toner is dropped and collected below the developing container 41 as indicated by reference numeral 53.

In this embodiment, the photosensitive member 1 and the developing roller 40
Is of a rubbing type, and if the resistance value is too low, the toner may be a polymerized toner and a high resistance of 10 ⁶ Ωcm or more or an insulating toner may be used in view of leakage. In the polymerized toner, at the stage of polymerizing a polymer from a monomer, toner particles are produced by incorporating a colorant, a charge control agent, and the like into the polymer particles, so that spherical particles are obtained, and the charges are uniformly charged on the spherical particles. Therefore, due to point contact with the surface of the photoreceptor, the number of contact points with respect to one particle is small and the image force is small.

The developing roller 40 is provided on the surface layer 1 of the photosensitive member 1.
c is rubbed with a nip width of 1 mm or more (preferably 1 to 2 mm), and rotates in the same direction at the rubbing position. (Preferably, the toner layer thickness is 0.3 mg / cm ^{2 to} 0.9 mg /
The speed is set to 1.1 to 6.0 times of cm ² . More preferably, the toner layer thickness is 0.7 mg.
/ Cm ² is set to a speed of 1.2 to 5.0 times.

The layer thickness of the toner particles is 0.3 mg / c.
m ^{2 to} 1.0 mg / cm ² , preferably 0.3 mg / cm ²
cm ^{2 to} 0.9 mg / cm ² , more preferably 0.4 m
It is set to ^{g / cm 2 ~0.8mg / cm 2} . The transfer roller 5 uses a conductive roller to increase the transfer efficiency to the recording paper 9, applies a transfer bias having a polarity opposite to the charging potential of the toner, and uniformly presses the peripheral surface of the photosensitive drum 1. , And is rotatable in synchronization with the drum 1.

The cleaning means 6 is located on the downstream side of the transfer roller 5 and rotates a conductive fiber such as polyester, acrylic, rayon containing carbon, nylon, vinylon or the like around a rotation axis or by winding the fiber. It is formed as a conductive cleaning roller 6a in a roller shape, and is arranged so that its outer peripheral surface contacts the surface of the photoconductor 1 and rotates in the same direction as the rotation direction of the photoconductor 1 at the contact position. The conductive cleaning roller 6a may have a sponge shape in which countless large and small holes are formed on the surface thereof and countless protrusions are also formed on the inner peripheral surface of the hole.

The paper dust of the recording paper 9 is smaller than that of the toner, and the paper dust has a complicated shape and has numerous thread-like whiskers. The conductive roller 6a can remove the toner with a force smaller than the toner removing force. Further, the paper dust attached to the toner is sucked together with the toner by the conductive roller 6a and is restrained by the fibrous peripheral surface. In addition, the sponge has countless large and small holes formed on its surface, and countless protrusions are also formed on the inner peripheral surface of the hole, so that the paper dust is absorbed together with the toner, and the paper dust is It is restrained in the hole or the inner peripheral surface of the hole.

The paper dust is smaller than the polymerized toner, and the shape of the paper dust is not spherical as compared to the polymerized toner, but has a complicated shape, and a myriad of thread-like whiskers are present. The rate of being restrained around the sponge or the fiber is much higher than that of the polymerized toner. Therefore, even if the toner is returned to the photoreceptor surface during non-transfer, it is extremely small that the paper dust adheres to the toner and is returned.

The charging unit 8 was uniformly charged on the photosensitive member by a well-known scorotron charger. In the figure, 81 is a corona discharge wire, 82 is a control grid, 8
3 is a discharge bias and 84 is a charge control bias.

Since the roller 6a of the cleaning means 6 is formed of a conductive material, the roller 6a may also serve as a charge removing roller for removing charge on the surface of the photosensitive member 1 instead of the charge removing lamp 7. Alternatively, the charge removing lamp 7 and the charging unit 8 may be removed, and the photosensitive member 1 may be charged by the roller 6a.

Since the present embodiment is configured as described above, the charging device 8 has a charging control bias appropriately set between about 400 V. After the surface potential Vo of the photosensitive drum 1 is charged to the above set value, a predetermined latent image is exposed by the exposure head 2. Thereafter, a toner image created by a polymerization method is attached to the latent image by the developing unit 4 and transferred to a recording medium (recording paper) 9 inserted between the photoconductor 1 and the transfer roller 5. At this time, at the transfer position of the transfer roller 5, by making the peripheral speed of the transfer roller greater than the peripheral speed of the photoconductor, a dynamic pressing force is applied to the back surface of the recording paper, and the transfer roller Since the back surface of the recording paper is pressed with a wide surface, the transfer efficiency is improved.

When the positively charged toner adheres to the latent image on the surface of the photoreceptor and moves to the transfer position of the transfer roller 5, a negatively applied potential of the transfer roller 5 causes the recording paper 9 to move.
A toner image adheres to the surface of. At this time, if the conductive roller 6a of the cleaning unit 6 forms a conductive roller electric field different from the transfer roller electric field formed by the potential applied to the transfer roller 5, the transfer roller electric field is affected by the conductive roller electric field. The conductive roller 6a needs to be located sufficiently far from the transfer roller 5.

The recording paper 9 is sent out from a storage (not shown), inserted between the photoreceptor 1 and the transfer roller 5, and sent out to a fixing step (not shown) after the transfer. In this process, especially before and after including the transfer process, the paper dust is separated from the recording paper by pressure contact with a roller or the like. Then, the separated paper dust adheres to the surface of the photoreceptor 1 and is transferred to the cleaning unit 6 located on the downstream side of the transfer roller 5.

At the time of transfer, the transfer roller 5 is used to transfer the positively charged toner image on the surface of the photoreceptor to the recording paper 9.
When a negative voltage is applied to the conductive roller 6a and the negative voltage is also applied to the conductive roller 6a, the paper dust adhering to the residual toner on the surface of the photoreceptor is attracted to the conductive roller 6a together with the toner and is restrained. You.

Therefore, most of the residual toner is removed by the cleaning means 6 and the amount of the residual toner transferred to the developing container 41 is small. When the transfer of one page is completed,
When there is no need to apply a voltage to the transfer roller side,
The potential on the conductive roller side is inverted to a positive potential. As a result, the toner moves from the conductive roller side to the photoconductor side. At the time of non-transfer of the transfer roller, the transfer is not affected even if the polarity of the voltage applied to the conductive roller is reversed.

On the other hand, in FIG. 2, the residual toner not transferred to the recording paper 9 is restrained at the time of transfer by the cleaning means 6, but it is considered that a small amount of toner is transferred to the developing container 41 as residual toner 49. The residual toner 49 contacts the elastic body 42 of the developing roller 40 again, and at the contact position between the developing roller 40 and the photosensitive member 1, the peripheral speed is higher than that of the photosensitive member 1. The residual toner 49 is scraped off by the elastic body 42 of the roller 40 as indicated by reference numeral 51, and new toner 48 develops the latent image on the surface of the photoconductor 1.

The residual toner denoted by reference numeral 51 contains a small amount of the photoreceptor powder obtained by polishing the surface of the photoreceptor 1. Should be considered to contain powder. This residual toner 51 is
Although the toner is scraped off by the developing roller 42 and falls below the developing container 41, it may be attached to the surface of the developing roller 42 and transported as indicated by reference numeral 52.
In the nip area where both rollers affect each other, the supply roller 45 is rotated downward in the direction opposite to the developing roller 42 and is dropped below the developing container 41 as shown by reference numeral 53 and collected.

The residual toner 53 mixes with the new toner in the developing container 41, but is diluted because the amount is small relative to the amount of the new toner. Therefore,
It is desirable that the residual toner 53 be recirculated in the developing container 41, injected into the new toner near the entrance where the new toner is supplied, and stirred.

Further, at the time of non-transfer, the toner restrained at the time of transfer by the cleaning means 6 is:
The toner is returned to the photosensitive member again by reversing the voltage applied to the conductive roller 6a, but is transferred to the developing container 41 as residual toner 49 in FIG.
The voltage applied to the developing roller 40 is also inverted so that it is collected by the developing roller 40 when it comes into contact with the elastic body 42 again.
Since the peripheral speed of the photoconductor 1 is higher than that of the photoconductor 1, the residual toner 49 is slightly scraped off by the elastic body 42 of the developing roller 40 as indicated by reference numeral 51.

The residual toner denoted by reference numeral 51 contains a small amount of photoreceptor powder obtained by polishing the surface of the photoreceptor 1, and a small amount of paper depending on the degree of construction of the cleaning unit 6. Should be considered to contain powder. This residual toner 51 is
Although the toner 52 is scraped off by the developing roller 42 and falls below the developing container 41, the toner 52 adhered to the surface of the developing roller 42 and transferred is opposite to the developing roller 42 in a nip area where both rollers affect each other. By the supply roller 45 rotating in the direction, as shown by reference numeral 53, the developer is dropped and collected below the developing container 41.

As described above, the cleaning means 6
Since it is possible to replace the conductive roller 6a after the paper dust is taken in by the conductive roller 6a and absorbs the paper dust generated by printing of a predetermined number or more, the conductive roller 6a can be replaced. It is possible to provide a simple image forming apparatus.

In this embodiment, since the latent image on the photosensitive member 1 is developed while forming a thin layer of toner particles formed by the polymerization method, the charge is uniformly charged on the spherical toner particles. In addition, due to point contact with the surface of the photoreceptor, the number of contact points with respect to one toner particle is small, and the image power is small.
There is little 'fogging' phenomenon, paper dust is smaller than polymerized toner, and paper dust is not spherical in shape than polymerized toner, it has a complicated shape, and there are countless thread-like whiskers By doing so, the rate of being restrained by the sponge is much higher than that of the polymerized toner, and it is possible to provide a good image forming apparatus by eliminating paper dust together with the fogging phenomenon.

Further, in this embodiment, when the image formed on the photosensitive member is transferred to the recording paper, the cleaning means 6 removes the paper powder which is the peeling powder of the recording paper adhered on the photosensitive member. Therefore, the toner is transferred to the developing roller 40 while being attached to the photoreceptor 1, and is transferred to the developing roller 40.
As a result, the amount collected in the developing container 41 together with the residual toner becomes extremely small, and the image is disturbed by the paper dust mixed with the toner due to long-term use.

Further, in this embodiment, as described above, the potential of the conductive roller is made variable, and the potential at the time of transfer and the time of non-transfer (that is, at the time of transfer when the transfer voltage is Means a state in which a transfer voltage is not applied), and the inversion voltage is applied to the conductive cleaning roller 6a by switching between transfer and non-transfer by inverting the potential of the conductive roller. At the time of transfer, the conductive cleaning roller 6a absorbs the paper dust together with the toner, so that a small amount of the residual toner is transferred to the developing container 41 side, and before the paper dust of the recording paper 9 reaches the developing container 41 at the time of development. Substantially eliminated, good image formation can be performed.

In this embodiment, the residual toner travels twice from the photosensitive member to the conductive cleaning roller and from the conductive cleaning roller to the photosensitive member twice. At that time,
The paper powder separates from the toner and the rate of being constrained by the conductive cleaning roller increases, and the toner can be prevented from accumulating on the conductive cleaning roller and overflowing in the cleaning unit 6.

The transfer roller 5 and the conductive cleaning roller 6a do not affect each other when the paper dust is removed during the transfer, especially when the potential difference between them is large. It is desirable to arrange them so as to be spaced apart from each other.

When removing the paper dust on the surface of the photoconductor by the conductive cleaning roller, the peripheral speed of the conductive cleaning roller and the peripheral speed of the photoconductor are made different,
Desirably, when the peripheral speed of the conductive cleaning roller is configured to be higher than that of the photoconductor, the contact points on the surface of the photoconductor sequentially contact new contact points of the conductive cleaning roller, and the conductive cleaning roller Since the contact is made on a wide surface, the toner absorption efficiency is improved, and as a result, the removal efficiency for removing paper dust is improved.

As described above, in the present embodiment, the developing roller 40 is rubbed against the surface of the surface layer 1c of the photoconductor 1, and the peripheral speed of the photoconductor 1 is made different from the surface layer 1c. Is developed, the toner can be collected in the developing container together with the development in the developing container 41, and the residual toner not used for the development can be reused.

As described in detail above, according to the present embodiment,
Since a cleaning unit having an applied voltage reversing unit is provided on the downstream side of the transfer unit, when transferring a formed image on the photoreceptor to a recording medium, the release powder of the recording medium adheres to the photoreceptor. The paper dust is eliminated, the paper dust is transferred in a state where it adheres to the photoreceptor, and the amount collected in the developing container together with the residual toner becomes extremely small. Is very little disturbed.

Further, by inverting the potential of the conductive roller of the cleaning means at the time of transfer and at the time of non-transfer,
Residual toner is transferred from the photoconductor to the conductive cleaning roller.
Further, the conductive cleaning roller moves back and forth twice to the photoreceptor, and a large lump of the residual toner is pulverized into small pieces. At this time, the paper powder separates from the toner and the rate of being constrained by the conductive cleaning roller increases. At the same time, it is possible to prevent toner from collecting on the conductive cleaning roller and overflowing in the cleaning unit 6.

[0061]

【Example】

Example (1) An a-Si photosensitive member having a surface layer having a thickness of 25 μm was prepared, and charging was performed using a scorotron method V0: 350.
V, development is a non-magnetic one-component system, and the developing roll is a conductive roller having a diameter of 18 mm and a volume specific resistance of 5 × 10 ⁶ Ω · c.
m, surface roughness 10 microns or less, development nip about 1 mm,
Developing linear speed 120mm / sec (Photoconductor linear speed 60mm / s
ec), the developing blade has a thickness of 1.3 mm and a resistance value of 1
0 ⁴ Ω · cm or less, supply roll diameter 12 mm, resistance value: 10 ⁴ Ω · cm or less, nip about 1 m with development roll
m, each bias value is a developing blade 350 V, a supply roller 350 V, a potential difference 220 V between the photosensitive member and the developing roller,
The thickness of the toner layer is 0.7 mg / cm ² , and the toner used is a styrene-acrylic material produced to have an average particle size of 8 μm by polymerization and a pulverization method. The transfer current was set to 20 to 30 microamps in the method.

Normal temperature and normal humidity (N / N) at a temperature of 20 ° C. and a humidity of 60%
N), the transfer efficiency of each toner was measured at a high temperature and a high humidity (L / L) of 33 ° C. and a humidity of 85%, and the results are shown in Table 1.

[0063]

[Table 1] From Table 1, it can be seen that the transfer efficiency of the polymerization toner is superior.

[0064]

As described above, according to the present invention, it is possible to provide an image forming apparatus capable of preventing the image quality of an image from deteriorating due to a release powder of a recording medium.

[Brief description of the drawings]

FIG. 1 is an embodiment of an image forming apparatus to which the present invention is applied.

FIG. 2 is a configuration diagram illustrating a configuration inside a developing container.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor drum 1a conductive substrate 1b photoconductive layer 1c surface layer 2 exposure head 3 optical system 4 developing unit 6 cleaning means 6a conductive roller 8 charging device 40 developing roller 41 developing container

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keiji Itsukushima 704-19 Noshino, Tamaki-cho, Machi Prefecture Mie Prefecture Inside the Mie Tamaki Plant, Kyocera Corporation (72) Inventor Yoshio Ozawa 704-19 Noshino, Tamaki-cho, Tamaki-cho, Mie Prefecture Kyocera Corporation Mie Tamaki Factory

Claims (4)

[Claims] 1. An image forming apparatus configured to be able to transfer a toner image carried on a surface of a photoreceptor to a recording medium by a transfer unit, wherein a conductive material that contacts the surface of the photoreceptor downstream of the transfer unit. A cleaning means is provided, and a voltage capable of inverting the polarity is applied to the conductive cleaning means, and the applied voltage is inverted and applied to the conductive cleaning means during transfer and non-transfer of the transfer means. An image forming apparatus comprising: 2. The method according to claim 1, wherein a difference in forward peripheral speed between the conductive cleaning unit and the photoconductor is provided, and preferably, the peripheral speed of the conductive cleaning unit is higher than that of the photoconductor. Image forming apparatus. 3. An image forming apparatus according to claim 2, wherein said conductive cleaning means is formed of a sponge, and is configured to be able to capture a peeling powder from a recording medium by said peripheral speed difference. 4. The image forming apparatus according to claim 1, wherein the toner is manufactured by a polymerization method.