JP2001166556A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device where a high speed as well a better color image can be formed in a tandem system. SOLUTION: In a tandem system color laser printer 1 where a multiple number of processing units 11 for each color that are provided with developing cartridges 15, photoreceptor drums 16, LED arrays 14, scorotron type electrifying devices 17 and primary transfer rolls 12, each of the photoreceptor drums 16 is constituted from amorphous silicon and the device is also constituted to be a cleanerless system recovering residual toner on each photoreceptor drum 16 after transfer by each developing roll 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a color laser printer.

[0002]

2. Description of the Related Art As a laser printer for forming a color image, for example, a developing roller for carrying a toner, a photosensitive drum disposed opposite to the developing roller and forming an electrostatic latent image, and A so-called tandem type is known, in which a plurality of chargers and exposure devices for forming an electrostatic latent image on the photosensitive drum are provided for each color. I have.

In such a tandem type color laser printer, a visible image developed for each color is sequentially transferred to paper for each color, so that the color image is printed at substantially the same speed as that for forming a monochrome image. Can form an image,
It is very good in this respect. That is, for example, in a so-called intermediate transfer type color laser printer, a single photosensitive drum is developed for each color, and is transferred once to an intermediate transfer drum to form a multi-color image, and then transferred to paper. Since a visible image of each color is superimposed on the intermediate transfer drum, it takes time for the number of colors in one transfer. For example, if the number of colors is four, four times as long as a monochrome image is formed. It takes time and it is difficult to form a color image at high speed. In this regard, a tandem color laser printer can form a color image at high speed without such a problem.

[0004]

However, when a multi-color image is formed in such a tandem-type color laser printer, there is a possibility that an image formation defect due to color misregistration or color mixing may occur. That is, in the tandem system, for each color, a photosensitive drum, a charger and an exposure device are provided. For example, when the photosensitive drum is replaced, the position of the photosensitive drum is slightly shifted, or
If the position shift occurs when the charger or exposure device is removed or moved for the replacement, or when the contactor moves slightly during the replacement work, the color shift of the formed image is corrected. Occurs.

Further, in the tandem system, since the image is transferred for each color, if the resistance value of the object to be transferred is changed, the visible image is not transferred stably. However, there is a possibility that the photosensitive drum on the downstream side may adhere again to cause color mixing.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an image forming apparatus capable of forming a high-speed and better color image by a so-called tandem system. It is to provide a device.

[0007]

In order to achieve the above object, the invention according to claim 1 is directed to a developer carrying member for carrying a non-magnetic one-component developer and an electrostatic latent image formed by a developer. An image forming apparatus comprising: an image carrier for carrying a visible image formed by being developed; and a plurality of electrostatic latent image forming means for forming an electrostatic latent image on the image carrier for each color. In the apparatus, the image carrier is made of amorphous silicon, and after a visible image carried on the image carrier is transferred to a transfer medium, a developer remaining on the image carrier is removed. It is characterized in that it is configured to be collected by the developer carrier.

According to such a configuration, since the image carrier is made of amorphous silicon having excellent abrasion resistance, there is no need to replace it. So, for example,
When replacing the image carrier, the position may shift slightly,
Alternatively, the position of the electrostatic latent image forming unit does not shift due to the replacement, and the color shift of the image due to such a position shift can be effectively prevented.

If the image carrier is made of amorphous silicon, it is not necessary to replace the image carrier. For example, the image carrier and two members usually arranged on both sides of the image carrier, that is, The developer container filled with the developer and the waste developer container for collecting the developer remaining after the transfer may be integrally configured so as to eliminate the need for individual replacement. It is not possible to replace the two replacement parts separately for each color, which requires a great deal of work. In this configuration, the developer remaining on the image carrier is collected by the developer carrier. Therefore, a waste developer accommodating section for collecting the remaining developer becomes unnecessary, and as a result, such labor can be greatly reduced. In addition, since the waste developer accommodating portion is usually opened toward the image carrier, at the time of replacement, hands and the like may be stained by the waste developer. Such defects can be avoided. Further, the displacement of the electrostatic latent image forming means does not occur due to the replacement of the waste developer accommodating portion, and the reliability of the apparatus can be further improved.

[0010] The invention described in claim 2 is the same as the claim 1.
Wherein the developer is a polymerized toner obtained by polymerizing a polymerizable monomer.

[0011] The polymerized toner is spherical and has extremely good fluidity, so that it is well transferred from the image carrier to the transfer medium. Therefore, the amount remaining on the image carrier after transfer can be significantly reduced. Further, the polymerized toner has good fluidity and is not easily affected by frictional force or the like, and therefore easily behaves by electric field force. Therefore, the polymerized toner remaining on the image carrier after the transfer is reliably recovered by the developer carrier as long as it is charged to a normal polarity when facing the developer carrier,
The polymerized toner transferred to the transfer medium rarely adheres to the image carrier that comes in contact later.

Further, the invention described in claim 3 is the first invention.
In the invention described in or 2, in the moving direction of the image carrier, the image is transferred to the transfer medium at a position downstream of a position at which the image is transferred to the transfer medium, and at a position upstream of a position facing the developer carrier. A cleaning roller for temporarily recovering the developer remaining on the image carrier after the cleaning is provided, and when the cleaning roller is opposed to an image area of the image carrier on which an image is formed. Electrically holding the collected developer, and when the developer is opposed to a non-image area where an image is not formed on the image carrier, the collected developer is electrically discharged onto the image carrier. It is characterized by being constituted.

According to such a configuration, the developer remaining on the image carrier after being transferred from the image carrier to the transfer medium is once electrically held by the cleaning roller, and then the cleaning roller is moved by the cleaning roller. When the non-image area of the carrier is opposed to the non-image area, the carrier is electrically discharged onto the image carrier again, and thereafter, is collected by the developer carrier.

The invention described in claim 4 is the first invention.
In the invention according to any one of Items 3 to 3, the developer carried on the developer carrier and the image carrier on which the electrostatic latent image is formed are arranged at a predetermined interval. It is characterized by having.

According to such a configuration, since the developer carrier and the image carrier are not in contact with each other, the developer carrier is formed integrally with the developer accommodating portion, and when the developer is supplied,
Even in a configuration in which the image carrier is replaced as a unit, the developer carrier does not come into contact with the image carrier at the time of replacement, so that the image carrier is not displaced due to the replacement. Therefore, it is possible to effectively prevent the image from being misaligned due to such misalignment. Further, even during development, no frictional force acts between the developer carrier and the image carrier, so that the frictional force does not cause disturbance in driving of the image carrier, There is no occurrence of color shift due to this. Further, since the developer is not rubbed between the developer carrier and the image carrier, deterioration of the developer can be reduced. In particular, when the developer is rubbed by the image carrier made of hard amorphous silicon, the deterioration is remarkable, but such a problem can be prevented well.

The invention described in claim 5 is the first invention.
5. The invention according to any one of items 4 to 4, wherein the transfer medium is an intermediate transfer medium for transferring a multicolor image transferred from each of the image carriers to a recording medium, and the transfer medium is transferred to the intermediate transfer medium. And a transfer unit for transferring the multicolor image onto the recording medium.

According to this configuration, the visible image carried on each image carrier for each color is temporarily transferred to the intermediate transfer medium, and the respective colors are superimposed on the intermediate transfer medium, so that the multicolor image is formed. After being formed as an image, the image is collectively transferred from the intermediate transfer medium to a recording medium by a transfer unit.

For example, if the configuration is such that a visible image carried for each color on each image carrier is directly transferred to a recording medium as a transfer medium, the type of recording medium, for example, paper or O
Due to differences in HP and the like, differences in thickness, width, and resistance value, or changes in resistance value due to the environment, stable transfer from each image carrier cannot be performed. As a result, for example,
The developer that has already been transferred to the transfer medium may adhere again to the image carrier that comes in contact later, and may cause color mixing. However, according to such a configuration, all of the visible images carried on each image carrier are once transferred to the intermediate transfer medium, and then collectively transferred from the intermediate transfer medium to the recording medium. Transfer from each image carrier is stable,
As a result, the occurrence of color mixing can be effectively prevented.

In such a configuration, the developer is transferred from the image carrier to the intermediate transfer medium and further transferred from the intermediate transfer medium to the recording medium, that is, transferred twice. However, in such a case, the use of a polymerized toner having good transfer efficiency can effectively prevent the deterioration of the image quality.

The invention described in claim 6 is the same as the invention in claim 5
In the invention described in (1), in the transport direction of the recording medium, downstream of the transfer unit, a transport direction switching unit that switches a transport direction of the recording medium onto which a multicolor image has been transferred is provided, and the transport direction switching unit is provided. By switching the conveyance direction of the recording medium on which the multicolor image has been transferred to one surface, the recording medium is again conveyed to the transfer means so that the multicolor image is transferred to the other surface. , Wherein a multicolor image can be transferred to both sides of the recording medium.

According to this structure, the recording medium having the multicolor image transferred to one surface is again conveyed to the transfer device by the conveyance direction switching device so that the multicolor image is transferred to the other surface. After that, a multicolor image is formed on the other surface by the transfer means.

The invention described in claim 7 is the first invention.
In the invention according to any one of the above items (1) to (6), the electrostatic latent image forming unit includes a charging unit configured to charge the image carrier,
An exposure unit for exposing the charged image carrier to light, wherein the charging unit is arranged so as not to contact the image carrier.

According to such a configuration, the developer remaining on the image carrier after being transferred to the recording medium by the transfer unit passes through the charging unit arranged so as not to contact the image carrier, and then the developing agent is charged. When facing the developer carrier, the developer is collected by the developer carrier. When the developer remaining after the transfer passes through the charging unit, the charging unit is operated to charge the developer to a normal polarity. Therefore, for example, even if there is a developer charged to the opposite polarity due to the bias voltage at the time of transfer, it can be satisfactorily collected by the developer carrier.

The invention described in claim 8 is the same as the invention described in claim 7.
In the invention described in (1), the developer is a developer charged to a positive polarity.

When the developer is a positively charged developer, a positive charging means can be used in reversal development.

The invention according to claim 9 is the first invention.
9. The invention according to any one of claims 8 to 8, further comprising a layer thickness regulating member for pressing the developer carrier to form a thin layer of developer, wherein the layer thickness regulating member is provided on the developer carrier. Is characterized in that a pressing portion for pressing is made of silicone rubber.

According to such a configuration, since the pressing portion of the layer thickness regulating member is made of silicone rubber having good chargeability, the pressing portion is pressed by such a pressing portion and is carried on the developer carrying member. Developer is well charged. Therefore, the generation of the developer charged to the opposite polarity in the thin layer of the developer can be significantly reduced.

According to a tenth aspect of the present invention, there is provided a developer carrying member for carrying a non-magnetic one-component developer, and a visible image formed by developing an electrostatic latent image with the developer. In an image forming apparatus including a plurality of image carriers for carrying and a plurality of electrostatic latent image forming means for forming an electrostatic latent image on the image carriers, a visible image is formed from each of the image carriers. An intermediate transfer medium on which the image is transferred, and a transfer unit for transferring the multicolor image transferred on the intermediate transfer medium to a recording medium, and the visible image carried on the image carrier is The image forming apparatus is characterized in that the developer remaining on the image carrier after being transferred to the intermediate transfer medium is collected by the developer carrier.

According to such a configuration, the visible image carried on each image carrier for each color is temporarily transferred to the intermediate transfer medium, and the respective colors are superimposed on the intermediate transfer medium, so that a multicolor image is formed. After being formed as an image, the image is collectively transferred from the intermediate transfer medium to a recording medium by a transfer unit.
On the other hand, the developer remaining on each image carrier without being transferred to the intermediate transfer medium is collected by the developer carrier.

For example, if the configuration is such that a visible image carried on each image carrier for each color is directly transferred to a recording medium, the type of recording medium, for example, the difference in paper or OHP, the thickness, etc. Stable transfer cannot be performed from each image carrier due to a difference in the width and the resistance value, or a change in the resistance value due to the environment. As a result, for example, the development has already been performed on the intermediate transfer medium. The agent may adhere again to the image carrier that comes into contact thereafter, causing color mixing. However, according to such a configuration, all of the visible images carried on each image carrier are once transferred to the intermediate transfer medium, and then collectively transferred from the intermediate transfer medium to the recording medium. The transfer from each image carrier is stable, so that even if the developer remaining on the image carrier is collected by the developer carrier, color mixing does not occur and a good multicolor image can be formed. Formation can be achieved.

According to an eleventh aspect of the present invention, in accordance with the tenth aspect of the present invention, there is provided:
A transport direction switching unit that switches a transport direction of the recording medium on which the multicolor image is transferred, wherein the transport direction switching unit switches a transport direction of the recording medium on which the multicolor image is transferred to one surface. By transporting the recording medium to the transfer unit again so that the multicolor image is transferred to the other surface, the multicolor image can be transferred to both sides of the recording medium. Features.

According to such a configuration, the recording medium having the multicolor image transferred to one surface is again conveyed to the transfer device by the conveyance direction switching device so that the multicolor image is transferred to the other surface. After that, a multicolor image is formed on the other surface by the transfer means.

Further, in the invention according to claim 12, in the invention according to claim 10 or 11, the developer is:
It is a polymerized toner obtained by polymerizing a polymerizable monomer.

The polymerized toner has a spherical shape and an extremely good fluidity, so that it is well transferred from the image carrier to the intermediate transfer medium. Therefore, the amount remaining on the image carrier after transfer can be significantly reduced. Further, the polymerized toner has good fluidity and is not easily affected by frictional force or the like, and therefore easily behaves by electric field force. Therefore, the polymerized toner remaining on the image carrier after the transfer is reliably recovered by the developer carrier as long as it is charged to a normal polarity when facing the developer carrier, The polymerized toner transferred to the transfer medium rarely adheres to the image carrier that comes in contact later. Further, in such a configuration, the developer is transferred from the image carrier to the intermediate transfer medium, and further transferred from the intermediate transfer medium to the recording medium, that is, transferred twice, so that in some cases, Although the image quality may be reduced accordingly, the use of a polymerized toner having a good transfer efficiency can effectively prevent the image quality from being lowered.

According to a thirteenth aspect of the present invention, there is provided a developer carrying member for carrying a non-magnetic one-component developer and a visible image formed by developing an electrostatic latent image with the developer. In an image forming apparatus including a plurality of image carriers for carrying and a plurality of electrostatic latent image forming means for forming an electrostatic latent image on the image carriers, a visible image is formed from each of the image carriers. An intermediate transfer medium on which the multicolor image is transferred, and a transfer unit for transferring the multicolor image transferred to the intermediate transfer medium to a recording medium, and a multicolor image is transferred downstream of the transfer unit. A transport direction switching means for switching a transport direction of the recording medium, wherein the transport direction switching means switches a transport direction of the recording medium on which a multicolor image has been transferred onto one surface, and thereby the other surface. So that multicolor images are transferred to And conveyed to the transfer unit again the recording medium, is characterized by being configured so as to transfer the multicolor image on both surfaces of the recording medium.

According to such a configuration, the visible image carried on each image carrier for each color is temporarily transferred to the intermediate transfer medium, and the respective colors are superimposed on the intermediate transfer medium, so that the multicolor image is formed. After being formed as an image, the image is collectively transferred from the intermediate transfer medium to a recording medium by a transfer unit.
The recording medium on which the multicolor image has been transferred to one surface is again conveyed to the transfer device by the conveyance direction switching device so that the multicolor image is transferred to the other surface. A multicolor image is formed on the other surface.

[0037]

FIG. 1 is a side sectional view showing an embodiment of a color laser printer as an image forming apparatus according to the present invention. In FIG. 1, a color laser printer 1
Is provided with a feeder unit 4 for supplying paper 3 as a recording medium and an image forming unit 5 for forming a predetermined image on the supplied paper 3 in a main body casing 2.

The feeder unit 4 includes the main casing 2
The paper tray 6 detachably mounted on the bottom of the paper tray, the paper pressing plate 7 provided in the paper tray 6, and the paper feed roller 8 provided above one end of the paper tray 6 And a registration roller 10 provided downstream of the paper feed roller 8 in the transport direction of the paper 3.

The paper pressing plate 7 is capable of stacking the paper 3 in a stacked manner, and the end farther from the paper feed roller 8 is swingably supported, and the end closer to the paper feed roller 8 is vertically movable. , And is urged upward by a spring 9 from the back side. Therefore, as the amount of stacked paper 3 increases, the paper pressing plate 7
Is pivoted downward against the biasing force of the spring 9 with the end farther from the fulcrum as a fulcrum. The uppermost sheet 3 on the sheet pressing plate 7 is pressed from the back side of the sheet pressing plate 7 toward the sheet feeding roller 8 by a spring 9 and is fed one by one by the rotation of the sheet feeding roller 8. . The registration roller 10 is composed of two rollers on the driving side and the driven side.
After a predetermined registration, the sheet is sent to the image forming unit 5.

The image forming unit 5 includes a process unit 11, an intermediate transfer belt 25 as an intermediate transfer medium, a secondary transfer roller 30 as a transfer unit, a fixing unit 13, and the like.

The four process units 11 are provided in the upper portion of the main body casing 2, namely, a yellow developing process unit 11Y, a magenta developing process unit 11M,
A cyan developing process unit 11C and a black developing process unit 11K are provided in parallel in a horizontal direction at predetermined intervals. Each of the process units 11 includes a developing cartridge 15, a photosensitive drum 16 as an image carrier, an LED array 14 as an exposure unit for forming an electrostatic latent image forming unit, and a charging unit for forming an electrostatic latent image forming unit. Scorotron charger 1
7, a primary transfer roller 12 and the like.

The developing cartridge 15 is detachably mounted on the main body casing 2, and includes a developing roller 18 as a developer carrier, a layer thickness regulating blade 19 as a layer thickness regulating member, a supply roller 20, and a toner box. 2
1 and so on.

In the toner box 21, for each developing cartridge 15, as a developer, yellow is used for the yellow developing unit 11Y, magenta is used for the magenta developing unit 11M, and cyan and black are used for the cyan developing unit 11C. The process unit 11K has a positively chargeable nonmagnetic 1 having a black color.
Each component toner is filled. The toner in the toner box 21 is discharged from a toner supply port 22 opened below the toner box 21.

The toner includes a polymerizable monomer, for example, a styrene monomer such as styrene, and an acrylic monomer such as acrylic acid, alkyl (C1 to C4) acrylate, and alkyl (C1 to C4) methacrylate. A polymerized toner obtained by copolymerizing the monomer by a known polymerization method such as suspension polymerization is used.
Such a polymerized toner is spherical and has extremely good fluidity. In addition, such a toner is mixed with wax and the like, and in order to improve fluidity,
An external additive such as silica is added. The average particle size of such a polymerized toner is about 6 to 10 μm.

Further, by using a positively chargeable toner, a scorotron-type charger 17 for positive charging can be used in reversal development. For this reason, for example, if a scorotron charger 17 not in contact with the photosensitive drum 16 is used for negative charging, a large amount of ozone may be generated and the working environment may be reduced. By using the charger 17, a favorable working environment can be secured.

A supply roller 20 is rotatably disposed below the toner supply port 22, and a developing roller 18 is rotatably disposed behind the supply roller 20. . The supply roller 20 and the developing roller 18 are in contact with each other so that each of them is compressed to some extent.

The supply roller 20 has a metal roller shaft,
A roller made of a conductive foam material is covered. Further, the developing roller 18 has a metal roller shaft covered with a roller made of a conductive rubber material. More specifically, the roller portion of the developing roller 18 has a coating layer of urethane rubber or silicone rubber containing fluorine on the surface of a roller body made of conductive urethane rubber or silicone rubber containing fine carbon particles or the like. Coated. As described above, by coating the surface of the developing roller 18 with the urethane rubber or silicone rubber coating layer containing negatively chargeable fluorine, the positive chargeability of the toner carried on the surface is improved. Can be.

In the vicinity of the developing roller 18, a layer thickness regulating blade 19 is provided. The layer thickness regulating blade 19 includes a blade body 23 made of a metal leaf spring material.
And a pressing portion 24 provided at the tip end of the blade main body 23 as a pressing portion having a semicircular cross section made of insulating silicone rubber, and an end of the blade main body 23 opposite to the pressing portion 24. Are supported by the developing cartridge 15 near the developing roller 18, and the pressing portion 24 is pressed against the developing roller 22 by the elastic force of the blade body 23.

As described above, since the pressing portion 24 of the layer thickness regulating blade 19 is made of silicone rubber having good chargeability, the toner pressed by the pressing portion 24 and carried on the developing roller 18 has good properties. Is charged. Therefore, the generation of toner charged to the opposite polarity in the thin layer of the toner carried can be significantly reduced. As a result, the fogging of the photosensitive drum 16 can be reduced, and the toner charged to the opposite polarity is effectively prevented from being adhered to the endless belt 29 described below and then transferred to the photosensitive drum 16 which comes into contact with the toner again. be able to. Therefore, it is possible to effectively prevent the occurrence of color mixture caused by the toner charged to the opposite polarity.

The toner discharged from the toner supply port 22 is supplied to the developing roller 1 by the rotation of the supply roller 20.
8, the supply roller 20 and the developing roller 1
8 and is positively triboelectrically charged.
The toner supplied above is pressed by the pressing portion 24 of the layer thickness regulating blade 19 and the developing roller 1 with the rotation of the developing roller 18.
8 where the toner is further triboelectrically charged and carried on the developing roller 18 as a thin layer having a constant thickness.

The photosensitive drum 16 is disposed at the rear side of the developing roller 18 so as to be rotatable in a direction indicated by an arrow (clockwise) so as to face the developing roller 18 at a predetermined interval. The photosensitive drum 16 has a drum body grounded and a surface portion made of amorphous silicon. As described above, by forming the surface portion of the photosensitive drum 16 with amorphous silicon, the abrasion resistance of the photosensitive drum 16 can be significantly improved. Therefore, the exchange of the photosensitive drum 21 becomes unnecessary. Therefore, displacement of the photosensitive drum 16 due to replacement of the photosensitive drum 16 can be reliably prevented. Further, when the developing cartridge 15 is replaced, the photosensitive drum 16 and the developing roller 18 are not in contact with each other, so that the position of the photosensitive drum 16 is slightly shifted, or the LED array 14 or the scorotron type The position of the charger 17 does not shift, and color shift of an image due to such position shift can be effectively prevented.

The scorotron charger 17 is disposed above the photosensitive drum 16 at a predetermined interval so as not to contact the photosensitive drum 16. The scorotron charger 17 is a scorotron charger for positive charging that generates corona discharge from a charging wire such as tungsten, and is configured to uniformly charge the surface of the photosensitive drum 16 to a positive polarity. ing. In the laser printer 1, the charged potential on the surface of the photosensitive drum 16 after charging is set to be 450V.

As described above, the scorotron type charger 17
Is disposed so as not to contact the photosensitive drum 16, so that the toner remaining after the transfer is removed by the developing roller 18 in the cleanerless toner collection described later.
It is possible to prevent the toner from adhering to the scorotron charger 17 before being collected by the method, and to prevent the occurrence of poor charging due to this.

The LED array 14 is provided above the photosensitive drum 16 and is configured by arranging a large number of LEDs. The LED array 14 irradiates the surface of the photosensitive drum 16 with light emission of the LED based on predetermined image data. Like that.

After the surface of the photosensitive drum 16 is uniformly positively charged by the scorotron charger 17, the surface of the photosensitive drum 16 is
Exposure is performed by light emission from the D array 14, and an electrostatic latent image based on predetermined image data is formed. In the laser printer 1, the potential of the surface of the photosensitive drum 16 after exposure by the LED array 14 is set to 100V.

The developing roller 18 and the photosensitive drum 1 are generated by the bias voltage applied to the developing roller 18.
6, the positively charged toner carried on the developing roller 18 is opposed to the photosensitive drum 16 by the potential difference between the electrostatic latent image and the electrostatic latent image formed on the surface of the photosensitive drum 16. Drum 16 positively charged
Jumps to a portion of the surface of which is exposed by the LED array 14 and has a lowered potential, and is selectively carried to form a visible image. Thereby, reversal development for each color by so-called jumping development is achieved. You.
In the color laser printer 1, a DC voltage of 300 V and an AC voltage of 2 kV are applied to the developing roller 18 in a superimposed manner as a bias voltage.

According to such a jumping development, since the developing roller 18 and the photosensitive drum 16 are not in contact with each other, the developing roller 18 and the toner box 21 are integrally formed as the developing cartridge 15 so that the toner can be replaced when the toner is replaced. Even if the developing cartridge 15 is replaced,
Since the developing roller 18 does not come into contact with the photosensitive drum 16 at the time of the replacement, the photosensitive drum 1
6 does not occur, and it is possible to effectively prevent the image from being misaligned due to such misalignment. Also, in such a jumping development, at the time of development, a gap between the developing roller 18 and the photosensitive drum 16 is provided.
Since no frictional force acts on the photosensitive drum 16, such frictional force does not disturb the driving of the photosensitive drum 16, and the resulting color shift does not occur. Further, since the toner is not rubbed between the developing roller 18 and the photosensitive drum 16, the deterioration of the toner can be reduced. In particular, in the color laser printer 1 of the present embodiment, since the surface of the photosensitive drum 16 is made of hard amorphous silicon, when the toner is rubbed by the photosensitive drum 16, the deterioration is remarkable. Troubles can be satisfactorily avoided. Moreover, in the case of the polymerized toner,
The external additive added to the polymerized toner is easily buried, but such a jumping development can also satisfactorily prevent such external additive from being buried.

The primary transfer roller 12 is located downstream of the developing roller 18 in the rotation direction of the photosensitive drum 16 and
The photosensitive drum 1 is sandwiched by an endless belt 29 described later.
6 is disposed so as to face diagonally below. This one
The secondary transfer roller 12 has a metal roller shaft covered with a roller made of a conductive rubber material. Then, the visible image carried on the photosensitive drum 16 is transferred to the endless belt 29 while the endless belt 29 passes between the photosensitive drum 16 and the primary transfer roller 12.

The intermediate transfer belt 25 is connected to each photosensitive drum 16
, A first roller 26 provided downstream of the registration roller 10 in the transport direction of the sheet 3, and a first roller 26 above the first roller 26 and a yellow developing process unit 11Y, and a third roller 2 provided below the black developing process unit 11K at a predetermined distance from the second roller 27 in the horizontal direction.
8 is provided. In the first to third rollers 26 to 28, a horizontal line connecting the upper edges of the second roller 27 and the third roller 28 passes between the photosensitive drum 16 of each developing cartridge 15 and the primary transfer roller 12, respectively. In addition, the first roller 26 is disposed in a substantially triangular shape so as to be obliquely forward and downward of the second roller 27. An endless belt 29 is wound around the outer periphery of the first to third rollers 26 to 28. Between the second roller 27 and the third roller 28, the endless belt 29 16 and 1 each
It is movable in the direction of the arrow while being sandwiched between the next transfer roller 12. The material of the endless belt 29 is a resin such as conductive polycarbonate or polyimide in which conductive particles such as carbon are dispersed.

Then, the first to third rollers 26
By rotating the endless belt 29 sequentially with the respective photosensitive drums 16 by the rotation of the rotations 28 to 28, the visible images of each color formed on the respective photosensitive drums 16 are sequentially superimposed on the endless belt 29, thereby increasing the number. A color image is formed. That is, for example, when the yellow visible image formed on the photosensitive drum 16 by the yellow toner filled in the developing cartridge 15 of the yellow developing process unit 11Y is transferred onto the endless belt 29, then the magenta developing Process unit 11
The magenta visible image formed on the photosensitive drum 16 by the magenta toner filled in the M developing cartridge 15 is transferred onto the endless belt 29 on which the yellow toner image has already been transferred. The operation is performed by a cyan visible image formed by the cyan developing process unit 11C, a black developing process unit 1
The black visible image formed by 1K is superimposed and transferred, whereby a multicolor image is formed on the endless belt 29.

The secondary transfer roller 30 is used for the intermediate transfer belt 2
5, is disposed at a position facing the first roller 26 of the intermediate transfer belt 25 via the sheet 3 so as to be rotatable in the direction of the arrow (clockwise). The secondary transfer roller 30 has a metal roller shaft covered with a roller made of a conductive rubber material, and a predetermined transfer bias is applied. Then, the multicolor image formed on the endless belt 29 is collectively transferred to the paper 3 while the paper 3 passes between the endless belt 29 and the secondary transfer roller 30.

As described above, the visible image carried for each color on each photosensitive drum 16 is temporarily transferred onto the endless belt 29 of the intermediate transfer belt 25, and the endless belt 2
9, each color is superimposed to form a multi-color image.
It is collectively transferred to the sheet 3 by the next transfer roller 30. Therefore, for example, if the configuration is such that the visible image carried for each color on each photosensitive drum 16 is directly transferred to the paper 3, the difference in the type of the paper 3, for example, paper, OHP, etc.
Due to a difference in thickness, width and resistance value, or a change in resistance value due to the environment, stable transfer from each photosensitive drum 16 cannot be performed. As a result, for example, the transfer has already been performed on paper or OHP. In some cases, the remaining toner may adhere again to the photosensitive drum 16 that comes into contact later, causing color mixing. According to such a configuration, all the visible images carried on each photosensitive drum 16 are temporarily removed. After the image is transferred onto the endless belt 29, the image is collectively transferred onto the paper 3 from the endless belt 29, so that the transfer from each photosensitive drum 16 is stabilized, thereby effectively preventing the occurrence of color mixture. it can.

In the configuration using the intermediate transfer belt 25, the toner is transferred from the photosensitive drum 16 to the endless belt 29, and further transferred from the endless belt 29 to the sheet 3, that is, transferred twice. Therefore, in some cases, the image quality may be degraded accordingly. However, in the color laser printer 1 according to the present embodiment, since the polymerized toner having good transfer efficiency is used, such image quality is degraded. Is effectively prevented.

The fixing unit 13 includes a secondary transfer roller 30
And a heating roller 31, a pressing roller 32 pressed by the heating roller 31, and an upper portion of the heating roller 31 and the pressing roller 32. And a pair of transport rollers 33 provided downstream of the sheet 3 in the transport direction. The heating roller 31 is made of metal and includes a halogen lamp for heating. The multicolor image transferred on the sheet 3 by the secondary transfer roller 30 is transferred between the heating roller 31 and the pressing roller 32. Then, the sheet 3 is conveyed by a conveying roller 33 to a flapper 36 described below, which is disposed above the conveying roller 33 and downstream of the sheet 3 in the conveying direction. I have to. A pair of paper discharge rollers 34 is disposed on the rear side of the flapper 36 and downstream of the paper 3 in the transport direction, and when the flapper 36 is located at a paper discharge position described later, Paper 3 sent from conveyance roller 33
Is transported to the paper discharge roller 34, and the sheet 3 sent to the paper discharge roller 34 is discharged by the paper discharge tray 34
5 is discharged.

In the color laser printer 1 according to this embodiment having the above-described configuration, the intermediate transfer belt 2
The toner remaining on the photosensitive drum 16 after being transferred onto the endless belt 29 (hereinafter referred to as a residual toner) is collected by a developing roller 18, that is, the remaining toner is collected by a so-called cleanerless method. If the residual toner is collected by the cleanerless method, it is not necessary to provide each process unit 11 with a waste toner storage unit for collecting the residual toner, and therefore, such a replacement of the waste toner storage unit becomes unnecessary. , Such labor can be greatly reduced. In addition, since the waste toner container is usually opened toward the photosensitive drum 16, hands and the like may be stained by waste toner when the photosensitive drum 16 is replaced. Troubles can be avoided. Further, the positions of the LED array 14 and the scorotron-type charger 17 do not shift due to the replacement of the waste toner container, and the reliability of the apparatus can be further improved.

In particular, in the color laser printer 1 according to the present embodiment, the photosensitive drum 16 is made of amorphous silicon and its exchange is not required.
For example, a photosensitive drum 16, two members normally arranged on both sides of the photosensitive drum 16, that is, a developing cartridge 15 having a toner box 21 and a waste toner storage unit for collecting toner remaining after transfer are provided. It cannot be configured so as to save the time and labor of replacing it individually, and it takes a great deal of trouble to replace two replacement parts separately for each color. If the toner is collected by a simple cleanerless method, it is not necessary to replace the waste toner container, and such labor can be greatly reduced.

In the recovery of the residual toner in such a cleanerless manner, in the color laser printer 1, each process unit 11 faces the endless belt 29 of the intermediate transfer belt 25 in the rotation direction of the photosensitive drum 16. Downstream from the position where
Further, cleaning rollers 41 for temporarily collecting the remaining toner are disposed upstream of a position facing the scorotron-type charger 17 so as to be in contact with the photosensitive drum 16. This cleaning roller 41
Has a metal roller shaft covered with a roller made of a conductive rubber material. More specifically, the roller portion of the cleaning roller 41 is made of conductive silicone rubber,
It is formed from a rubber material such as urethane rubber or EPDM. Further, a predetermined bias voltage is applied to the cleaning roller 41 so that a potential difference between the cleaning roller 41 and the photosensitive drum 16 is within a range where no discharge occurs between the cleaning roller 41 and the photosensitive drum 16. By providing a potential difference between the photosensitive drum 16 and the photosensitive drum 16 in this manner, the remaining toner can be electrically held or discharged onto the photosensitive drum 16 again.

When the residual toner remaining on the photosensitive drum 16 faces the cleaning roller 41 due to the rotation of the photosensitive drum 16, the cleaning roller 4
1, a bias voltage of the opposite polarity is applied to the photosensitive drum 16. Then, the remaining toner is electrically collected by the cleaning roller 41.

The cleaning roller 41 is used for the photosensitive drum 1
6 is an image area where an image is formed, that is, the photosensitive drum 1 on which a visible image to be transferred to the endless belt 29 after passing through the cleaning roller 41 is formed.
When the toner is opposed to a predetermined area on the surface 6, the collection of the remaining toner is continued and the collected toner is kept electrically.

Next, the non-image area where the image is not formed on the photosensitive drum 16, that is, the photosensitive drum on which the visible image to be transferred onto the endless belt 29 after passing through the cleaning roller 41 is not formed. The polarity of the bias voltage applied to the cleaning roller 41 is changed when facing the predetermined area on the cleaning roller 41. Then, the collected toner is electrically discharged onto the photosensitive drum 16 again.

By providing such a cleaning roller 41, for example, due to changes in the environment, durability, and other transfer states, after the transfer, the toner is transferred onto the endless belt 29 so that it cannot be collected by the developing roller 18 alone. Even when the amount of the remaining toner increases, the remaining toner is temporarily collected by the cleaning roller 41 so that such a visible image of each color formed on the photosensitive drum 16 is removed. The effect of the residual toner can be reduced, and the development and transfer can be performed satisfactorily.

The timing at which the residual toner is released from the cleaning roller 41 may be set at a timing at which the released residual toner does not contact the area of the endless belt 29 where the image is transferred by the rotation of the photosensitive drum 16. .

After the residual toner collected by the cleaning roller 41 is discharged onto the photosensitive drum 16 again, the discharged residual toner is opposed to the scorotron-type charger 17 by the rotation of the photosensitive drum 16. At this time, the scorotron-type charger 17 is operated at least. Then, the remaining toner released from the cleaning roller 41 is reliably charged to the positive polarity by the scorotron charger 17. Thereby, for example, by the bias voltage at the time of transfer,
When the remaining toner is charged to a negative polarity, the remaining toner can be charged to a normal positive polarity again. When the remaining toner is charged to a positive polarity, the charge amount is reduced. Can be enhanced.

Thereafter, the positively charged toner jumps to the developing roller 18 again by the bias voltage applied to the developing roller 18 when the toner is opposed to the developing roller 18 due to the rotation of the photosensitive drum 16. Recovery of the residual toner is achieved. At this time, the remaining toner is
Since the charge amount is increased at the normal polarity, the charge is reliably collected by the developing roller 18.

The color laser printer 1 has:
Each process unit 11 is provided with a discharge lamp 50 for lowering the potential of the surface of the photosensitive drum 16 after the transfer. The neutralization lamp 50 is located on the downstream side of the position facing the primary transfer roller 12 in the rotation direction of the photosensitive drum 16 and on the upstream side of the position facing the cleaning roller 41. They are arranged to face each other at a predetermined interval. By the light emission of the discharging lamp 50, the potential of the surface of the photosensitive drum 16 after the transfer is lowered, and a predetermined potential difference between the surface and the cleaning roller 41 is ensured. Good toner recovery is achieved. In the color laser printer 1, the discharging lamp 50 is set so as to lower the potential on the surface of the photosensitive drum 16 to about 100V.

The color laser printer 1 has:
A cleaner 42 is provided for collecting the toner remaining on the endless belt 29 after the multicolor image is collectively transferred to the paper 3.

The cleaner 42 is provided for the intermediate transfer belt 25.
A cleaner brush 44, a collecting roller 45, a collecting box 46, and a scraping blade 47 are provided in a cleaner casing 43 disposed above the first roller 26 and between the first roller 26 and the second roller 27.

The cleaner brush 44 has a cylindrical body formed with radial brushes.
The brushes are rotatably disposed in a state where the brushes are in contact with each other. A bias is applied to the cylindrical main body so that a predetermined potential difference is applied between the main body and the endless belt 29.

The recovery roller 45 is made of a metal roller, and is rotatably disposed on the front side of the cleaner brush 44 so as to be in contact with the cleaner brush 44 in a contact state. In addition, a bias is applied to the collection roller 45 so that a predetermined potential difference is applied between the collection roller 45 and the cleaner brush 44.

The collection box 46 has an opening at the front side of the collection roller 45 and a portion facing the collection roller 45. The collection roller 4 is located near the opening.
5 is provided with a scraping blade 47 which is pressed against.

After the multicolor image is collectively transferred to the sheet 3, the toner remaining on the endless belt 29 is
When the cleaner brush 44 is scraped by the cleaner brush 44 when the cleaner brush 44 is opposed by the rotation of the first to third rollers 26 to 28, the cleaner brush 4
Attached to the brush by the bias applied to 4.
Thereafter, when the residual toner adhered to the cleaner brush 44 is opposed to the collection roller 45, the remaining toner is attached to the collection roller 45 by a bias applied to the collection roller 45, and then scraped by the scraping blade 47 to collect the collection box. Collected at 46.

The color laser printer 1 according to the present embodiment is provided with a reverse direction transport unit 49 for forming a multicolor image on both sides of the sheet 3. The reversing direction conveyance unit 49 conveys the sheet 3 on which a predetermined multicolor image has been formed on one surface by the fixing unit 13, toward the discharge roller 34 and again toward the secondary transfer roller 30. And a plurality of transport rollers 37 to 40 for transporting the paper 3 toward the secondary transfer roller 30.
And a reversing roller 48 for reversing the sheet 3 and transporting the sheet 3 toward the secondary transfer roller 30.

The flapper 36 is disposed above the fixing unit 13 and downstream of the transport roller 33 in the transport direction of the paper 3, and is a discharge position for transporting the paper 3 toward the discharge roller 34. 1 (a position indicated by a solid line in FIG. 1) and a reversing position (a position indicated by a virtual line in FIG. 1) for conveying the sheet 3 toward the secondary transfer roller 30.

Each of the transport rollers 37 to 40 comprises a pair of rollers on the driving side and the driven side, respectively.
6 to a reversing roller 48 disposed between the paper feed roller 8 and the registration roller 10 in the transport direction of the sheet 3;
It is provided for transporting the paper 3. That is, the transport roller 37 is disposed on the front side of the flapper 36, the transport roller 38 is disposed below the transport roller 37, and the transport roller 39 is disposed on the transport roller 38.
It is arranged below. Further, the transport roller 40 is disposed on the rear side of the transport roller 39.

Therefore, in a state where the flapper 36 is located at the reversing position, the sheet 3 sent from the fixing unit 13 is conveyed downward by the conveying rollers 37 and 38 after the conveying direction of the sheet 3 is reversed. After being conveyed to the rear side by the conveyance roller 40 from the conveyance roller 39, it is sent to the reversing roller 48.

The reversing roller 48 is composed of a pair of rollers on the driving side and the driven side. After nipping the rear end of the sheet 3 sent from the conveying roller 40, the reversing roller 48 changes the rotation direction and It is configured to convey the paper 3 toward it. The transport path between the transport roller 40 and the reversing roller 48 is configured such that its opening is narrow near the reversing roller 48. for that reason,
Although the paper 3 can be transported from the transport roller 40 to the reversing roller 48, the paper 3 cannot be transported from the reversing roller 48 to the transport roller 40, and therefore, is transported by the reversing roller 48. The paper 3 is conveyed toward the registration roller 10 without returning to the conveyance roller 40 side.

Thus, the sheet 3 is again registered with the endless belt 29 after the predetermined registration by the registration roller 10 in a state where the other surface on which the multicolor image is not formed faces the endless belt 29. It is sent between the transfer roller 30. Therefore, when the paper 3 passes between the endless belt 29 and the secondary transfer roller 30, the multicolor image is transferred to the surface opposite to the surface on which the multicolor image has already been formed. By being fixed by the rollers 13, a multicolor image is formed on both sides of the sheet 3.

In this way, if a multicolor image is formed on both sides of the sheet 3, the consumption of the sheet 3 can be reduced.
An environment-friendly color laser printer 1 that supports resource saving can be provided.

In such a configuration, since the multicolor image transferred to one surface is fixed by heating and then transferred again to the other surface, the multicolor image is transferred to the other surface. At the time of transfer, the resistance value of the paper 3 may change. However, in the color laser printer 1 according to the present embodiment, the visible image carried on each photosensitive drum 16 is transferred directly onto the endless belt 29 without being directly transferred onto the paper 3. Irrespective of such a change in the resistance value, it is possible to satisfactorily transfer from the photosensitive drum 16. Therefore, in such a configuration, even if the toner remaining on the photosensitive drum 16 is collected by the developing roller 18,
A good multicolor image can be formed without causing color mixing or the like.

Further, in the above-described color laser printer 1 of the present embodiment, since a non-magnetic one-component toner is used, it remains on the photosensitive drum 16 in a coherent amount like a magnetic toner. Therefore, the remaining toner is removed from the developing roller 18 by the cleanerless method.
As a result, it is possible to reliably collect the image, and to ensure the formation of a good image. In particular, since a polymerized toner having good fluidity is used, it is possible to transfer the toner from the photosensitive drum 16 onto the endless belt 29 satisfactorily, whereby the amount of the residual toner after the transfer can be significantly reduced. . Further, such a polymerized toner has good fluidity and is hardly affected by frictional force or the like, and thus easily behaves by the force of an electric field. Therefore, for the polymerized toner remaining on the photosensitive drum 16 after the transfer, the developing roller 1
When the photosensitive drum 16 is charged with a normal polarity when facing the photosensitive drum 8, the polymerized toner transferred to the endless belt 29 can be reliably collected by the developing roller 18; Is less likely to adhere again, so that the occurrence of color mixing can be effectively prevented.

In the color laser printer 1 of this embodiment, an intermediate transfer belt 25 is provided, and a visible image carried for each color on each photosensitive drum 16 is once transferred onto an endless belt 29, After forming a multicolor image, 2
The multi-color image is collectively transferred from the endless belt 29 to the paper 3 by the next transfer roller 30. However, depending on the purpose and use, the secondary transfer roller 25 may be provided without the intermediate transfer belt 25. By 30, a multicolor image may be formed by sequentially transferring a visible image carried on each photosensitive drum 16 for each color directly to the paper 3 as a transfer medium.

In the above-described configuration, the cleaning roller 41 is provided to temporarily collect the residual toner. However, depending on the specifications and image forming conditions, the cleaning roller 41 may not be provided. The toner may be directly collected by the developing roller 18. In such a case, when the residual toner after the transfer faces the scorotron type charger 17 due to the rotation of the photosensitive drum 16, the scorotron type charger 17 is operated to reliably charge the residual toner to the positive polarity. By doing so, it is preferable to ensure the recovery by the developing roller 18.

[0093]

As described above, according to the first aspect of the present invention, the image bearing member is made of amorphous silicon having excellent abrasion resistance, and the replacement thereof is not required. It is possible to prevent the displacement of the body and the electrostatic latent image forming means due to the replacement thereof, and to effectively prevent the color displacement of the image due to such displacement. In addition, by collecting the developer remaining on the image carrier by the developer carrier, it is not necessary to replace the waste developer accommodating section, so that the labor for the replacement is greatly reduced, and the hands and the like are stained at the time of replacement. Can be prevented from adhering. Further, it is possible to prevent the position of the electrostatic latent image forming means from being shifted due to the replacement of the waste developer accommodating portion, and to improve the reliability of the apparatus.

According to the second aspect of the present invention, by using the polymerized toner, the amount remaining after the transfer is significantly reduced, and efficient and reliable recovery can be achieved. Further, the polymerized toner has good fluidity and is not easily affected by frictional force or the like, and therefore easily behaves by electric field force. Therefore, the polymerized toner remaining on the image carrier after the transfer can be reliably recovered by the developer carrier if it is charged to a normal polarity when facing the developer carrier. Since the polymerized toner transferred to the transfer medium rarely adheres to the image carrier that comes in contact later, the occurrence of color mixing can be effectively prevented.

According to the third aspect of the present invention, the developer remaining after the transfer is once collected by the cleaning roller before being collected by the developer carrier.
For example, even if the amount of the developer remaining after the transfer becomes too large to be collected by the developer carrier due to changes in the environment, durability, and other transfer states, the cleaning roller temporarily collects the developer. By doing so, it is possible to prevent problems from occurring in image formation on the recording medium, that is, in development and transfer.

According to the fourth aspect of the present invention, since the developer carrier and the image carrier are arranged at a predetermined interval, the developer carrier is integrally formed with the developer accommodating portion. Even when the image carrier is replaced, the developer carrier does not come into contact with the image carrier, so that the displacement of the image carrier caused by the replacement can be prevented, and thus such a displacement can be prevented. Can effectively prevent color misregistration of an image. Also, even during development, no frictional force acts between the developer carrier and the image carrier,
Such frictional force does not cause disturbance in driving of the image carrier, and does not cause color shift due to the disturbance. Further, since the developer is not rubbed between the developer carrier and the image carrier, deterioration of the developer can be reduced. In particular, when the developer is rubbed by the image carrier made of hard amorphous silicon, the deterioration is remarkable, but such a problem can be prevented well.

According to the fifth aspect of the present invention, all of the visible images formed for each color on each image carrier are temporarily transferred to the intermediate transfer medium. It can be performed stably. As a result, the occurrence of color mixing can be effectively prevented. In such a configuration, the developer is transferred from the image carrier to the intermediate transfer medium, and further transferred from the intermediate transfer medium to the recording medium. For example, if a polymerized toner having good transfer efficiency is used, In addition, it is possible to effectively prevent the image quality from being reduced due to such two transfers.

According to the sixth aspect of the present invention, since a multicolor image can be formed on both sides of the recording medium, the consumption of the recording medium can be reduced, and the environment for resource saving can be realized. A gentle image forming apparatus can be provided.

In such a configuration, usually,
After heating and fixing the multicolor image transferred to one side,
Since the multicolor image is transferred to the other surface again, when the multicolor image is transferred to the other surface, the resistance value of the recording medium changes. Since the visual image is transferred directly to the intermediate transfer medium without directly transferring to the recording medium, the visual image can be transferred well from the image carrier regardless of such a change in the resistance value. . Therefore, in such a configuration, even if the developer remaining on the image carrier is collected by the developer carrier, it is possible to achieve good multicolor image formation without causing color mixing or the like. Can be.

According to the seventh aspect of the present invention, since the charging means is arranged so as not to contact the image carrier,
The developer remaining after the transfer does not adhere to the charging unit before being collected by the developer carrying member, and it is possible to avoid the occurrence of charging failure of the charging unit due to the adhesion. Further, for example, even if the developer remaining after transfer is charged to the opposite polarity due to the bias voltage at the time of transfer, the developer is returned to normal by operating the charging means when passing through the charging means. Polarity can be returned. Therefore, when the developer is opposed to the developer carrier, the developer is charged to a normal polarity, and the developer can be favorably collected by the developer carrier.

According to the invention, when the developer is a positively charged developer, a positive charging means can be used in the reversal development. for that reason,
For example, when a negative-type charging unit that does not come into contact with the image carrier is used, a large amount of ozone may be generated, which may cause a decrease in the working environment. , A good working environment can be secured.

According to the ninth aspect of the present invention, in a thin layer of the developer carried on the developer carrying member, the generation of the developer charged to the opposite polarity can be significantly reduced. Therefore, the fog of the image carrier can be reduced, and the developer charged to the opposite polarity can be effectively prevented from being adhered to the transfer medium and then transferred again to the contacting image carrier. . Therefore, it is possible to effectively prevent the occurrence of color mixture caused by the developer charged to the opposite polarity.

According to the tenth aspect of the present invention, all the visible images formed for each color on each image carrier are temporarily transferred to the intermediate transfer medium. It can be performed stably. Thus, even when the developer remaining on the image carrier is collected by the developer carrier, the occurrence of color mixing can be effectively prevented.

According to the eleventh aspect of the present invention, since a multicolor image can be formed on both sides of the recording medium, the consumption of the recording medium can be reduced, and an environment compatible with resource saving can be realized. A gentle image forming apparatus can be provided.

In such a configuration, usually,
After heating and fixing the multicolor image transferred to one side,
Since the multicolor image is transferred to the other surface again, when the multicolor image is transferred to the other surface, the resistance value of the recording medium changes. Since the visual image is transferred directly to the intermediate transfer medium without directly transferring to the recording medium, the visual image can be transferred well from the image carrier regardless of such a change in the resistance value. . Therefore, in such a configuration, even when the developer remaining on the image carrier is recovered by the developer carrier, it is possible to achieve good multicolor image formation without causing color mixing or the like. Can be.

According to the twelfth aspect of the present invention, by using the polymerized toner, the amount remaining after the transfer is significantly reduced, and efficient and reliable recovery can be achieved. Further, the polymerized toner has good fluidity and is not easily affected by frictional force or the like, and therefore easily behaves by electric field force. Therefore, the polymerized toner remaining on the image carrier after the transfer can be reliably collected by the developer carrier if it is charged to a normal polarity when facing the developer carrier. Since the polymerized toner transferred to the intermediate transfer medium rarely adheres to the image carrier that comes in contact later, the occurrence of color mixing can be effectively prevented. Further, in such a configuration, the developer is transferred from the image carrier to the intermediate transfer medium,
Further, the toner is transferred from the intermediate transfer medium to the recording medium.
It is possible to effectively prevent the image quality from being reduced due to the number of transfers.

According to the thirteenth aspect of the present invention, all the visible images formed for each color on each image carrier are temporarily transferred to the intermediate transfer medium, so that the transfer from each image carrier can be performed. It can be performed stably. As a result, the occurrence of color mixing can be effectively prevented. In addition, since a multicolor image can be formed on both sides of the recording medium, the amount of consumption of the recording medium can be reduced, and an environment-friendly image forming apparatus that supports resource saving can be provided.

Further, in such a configuration, usually, the multicolor image transferred to one surface is fixed by heating, and then the multicolor image is transferred again to the other surface. When transferring an image, the resistance value of the recording medium changes, but in this configuration, the visible image carried on each image carrier is not directly transferred to the recording medium, but is temporarily
Since the image transferred to the intermediate transfer medium is transferred, the image can be well transferred from the image carrier regardless of such a change in the resistance value. Therefore, it is possible to achieve good multicolor image formation without causing color mixing or the like.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a main part of an embodiment of a color laser printer as an image forming apparatus of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 color laser printer 3 paper 14 LED array 16 photosensitive drum 17 scorotron charger 18 developing roller 19 layer thickness regulating blade 24 pressing unit 25 intermediate transfer belt 30 secondary transfer roller 36 flapper 41 cleaning roller

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 21/14 G03G 21/00 372 F term (Reference) 2H027 DA50 EA09 EB04 EC20 ED08 ED16 ED27 EE07 EF09 FA11 2H030 AA06 AB02 AD01 AD02 AD03 AD05 AD06 BB23 BB33 BB42 BB71 2H068 DA00 FA27 FB13 FC08 2H077 AA37 AD02 AD06 AD13 AD23 BA10 DB14 DB15 DB16 EA14 EA24 FA23 GA13

Claims (13)

[Claims] 1. A developer carrier for carrying a non-magnetic one-component developer, an image carrier for carrying a visible image formed by developing an electrostatic latent image with a developer, and the image carrier An image forming apparatus including a plurality of electrostatic latent image forming means for forming an electrostatic latent image on a carrier, for each color, wherein the image carrier is made of amorphous silicon; An image, wherein the developer remaining on the image carrier is collected by the developer carrier after the visible image carried on the transfer medium is transferred to the transfer medium; Forming equipment. 2. The image forming apparatus according to claim 1, wherein the developer is a polymerized toner obtained by polymerizing a polymerizable monomer. 3. In the moving direction of the image carrier, after being transferred to the transfer medium, downstream of a position where the image carrier is transferred, and upstream of a position facing the developer carrier. A cleaning roller for temporarily recovering the developer remaining on the image carrier is provided, and when the cleaning roller is opposed to an image area of the image carrier on which an image is formed, the developer is recovered. It is configured to electrically hold the developer and electrically discharge the collected developer onto the image carrier when facing a non-image area where an image is not formed on the image carrier. The image forming apparatus according to claim 1, wherein: 4. The image forming apparatus according to claim 1, wherein the developer carried on the developer carrier and the image carrier on which the electrostatic latent image is formed are arranged at a predetermined interval. An image forming apparatus according to any one of claims 1 to 3. 5. The transfer medium is an intermediate transfer medium for transferring a multicolor image transferred from each of the image carriers to a recording medium, wherein the multicolor image transferred to the intermediate transfer medium is The image forming apparatus according to any one of claims 1 to 4, further comprising a transfer unit for transferring the image onto the recording medium. 6. A transport direction switching unit that switches a transport direction of the recording medium onto which a multicolor image has been transferred, downstream of the transfer unit in the transport direction of the recording medium, the transport direction switching unit comprising: By switching the conveyance direction of the recording medium having the multicolor image transferred to one surface, the recording medium is again conveyed to the transfer unit so that the multicolor image is transferred to the other surface, The image forming apparatus according to claim 5, wherein the image forming apparatus is configured to transfer a multicolor image to both sides of the recording medium. 7. The electrostatic latent image forming means includes a charging means for charging the image carrier, and an exposing means for exposing the charged image carrier, and wherein the charging means comprises: The image forming apparatus according to any one of claims 1 to 6, wherein the image forming apparatus is arranged so as not to contact the carrier. 8. The image forming apparatus according to claim 7, wherein the developer is a developer charged to a positive polarity. 9. A pressing part which presses on the developer carrier in the layer thickness regulating member, further comprising a layer thickness regulating member for pressing the developer carrier to form a thin layer of the developer. The image forming apparatus according to claim 1, wherein the image forming apparatus is made of silicone rubber. 10. A developer carrier for carrying a non-magnetic one-component developer, an image carrier for carrying a visible image formed by developing an electrostatic latent image with the developer, and the image carrier. An electrostatic latent image forming unit for forming an electrostatic latent image on a carrier, in an image forming apparatus including a plurality of each for each color, an intermediate transfer medium to which a visible image is transferred from each of the image carriers; The multi-color image transferred to the intermediate transfer medium, with a transfer means for transferring to a recording medium, after the visible image carried on the image carrier is transferred to the intermediate transfer medium, An image forming apparatus, wherein the developer remaining on the image carrier is collected by the developer carrier. 11. A transport direction switching unit that switches a transport direction of the recording medium onto which a multicolor image has been transferred, downstream of the transfer unit in the transport direction of the recording medium, the transport direction switching unit comprising: By switching the conveyance direction of the recording medium having the multicolor image transferred to one surface, the recording medium is again conveyed to the transfer unit so that the multicolor image is transferred to the other surface, The image forming apparatus according to claim 10, wherein the image forming apparatus is configured to transfer a multicolor image to both sides of the recording medium. 12. The image forming apparatus according to claim 10, wherein the developer is a polymerized toner obtained by polymerizing a polymerizable monomer. 13. A developer carrier for carrying a non-magnetic one-component developer, an image carrier for carrying a visible image formed by developing an electrostatic latent image with a developer, and the image carrier. An electrostatic latent image forming unit for forming an electrostatic latent image on a carrier, in an image forming apparatus including a plurality of each for each color, an intermediate transfer medium to which a visible image is transferred from each of the image carriers; A transfer unit for transferring the multicolor image transferred to the intermediate transfer medium to a recording medium, and a multicolor image is transferred downstream of the transfer unit in the transport direction of the recording medium. A transport direction switching unit that switches a transport direction of the recording medium, wherein the transport direction switching unit switches a transport direction of the recording medium on which a multicolor image is transferred to one surface, so that the other surface is Multicolor images are transferred The image forming apparatus is configured such that the recording medium is conveyed again to the transfer unit so that a multicolor image can be transferred to both sides of the recording medium.