JPH06118842A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain an image forming device capable of surely separating and removing paper powder from developer as to the electrophotographic image forming device of a copying machine, a facsimile and a printer. CONSTITUTION:This device is provided with a developer image carrier 10 carrying a developer image on its surface, a transfer member 15 transferring the developer image on a transfer paper 14, a member 16 to be cleaned to whose surface the paper powder peeled from the paper 14 is stuck, and a cleaning member 18 provided so as to be proximate to or abut on the member 16, and electric field is formed by providing a potential difference between the surfaces of the members 18 and 16. The proximate part or the abutting part of the surface of the member 18 to the member 16 is formed of an insulating layer. Then, the proximate part or the abutting part of the surface of the member 18 to the member 16 is formed of a conductive layer or a semiconducting layer, and the surface of the member 18 is moved to the abutting part or the proximate part. Furthermore, an electrostatic charging means electrostatically charging the paper powder is installed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a facsimile or a printer, which forms an image by an electrophotographic method.

[0002]

2. Description of the Related Art An image forming apparatus of this type is known, for example, from Japanese Patent Publication No. 3-72980.

A conventional image forming apparatus will be described below. FIG. 7 schematically shows a developing device used in a conventional image forming apparatus. In FIG. 7, reference numeral 40 is a developer carrier having a magnet group inside, 41 is a developer composed of magnetic powder and toner, 42 is a photosensitive drum, 43 is a scraper, 4
4 is a collected developer mixing chamber, 45 is a transfer member, 46 is a transfer sheet, 47 is a cleaning blade, 48 is a collected developer mixing means, and 49 is a lower hole 49a through which magnetic powder and toner can pass. , A large diameter recovery hole 49b at the top
Is a filter means that has formed.

The operation of the developing device configured as described above will be described below. First, the developer 41 is attracted to the surface of the developer carrier 40 by a magnetic force, and the electrostatic latent image formed on the photosensitive drum 42 is developed by the electrostatic force acting on the toner. After the development, the developer 41 remaining on the developer carrying member 40 is scraped off by the scraper 43 and guided into the recovered developer mixing chamber 44 through the recovery hole 49b. On the other hand, the developer image formed on the photosensitive drum 42 is transferred to the transfer paper 46 by the transfer member 45.
At the time of transfer, paper dust such as paper fibers attached to the photosensitive drum 42 is collected by the cleaning blade 47 together with the transfer residual developer, and is collected by the collected developer conveying member (not shown) into the collected developer mixing chamber 44. Carried. The developer collected from the developer carrier 40 and the photosensitive drum 42 is agitated and mixed by the collected developer mixing means 48 while being sent from the back of the paper surface to the front. The mixed developer flows out from the hole 49a and is adsorbed on the developer carrier 40 again to be used for development. On the other hand, the fibers of the paper conveyed together with the collected developer have a size of several tens of times the size of the developer, and therefore cannot pass through the hole 49a and remain in the collected developer mixing chamber 44.

[0005]

However, in the above-mentioned conventional configuration, the fibers 49 of the paper accumulate in the collected developer mixing chamber 44 along with the number of output images, and the hole 49a is gradually covered. Therefore, there is a problem that the collected developer cannot be supplied to the developer carrying member 40.

[0006] Also, small-sized paper powder is provided with a developer in a hole 49.
Since the toner flows out from a, frictional electrification between the toner and the magnetic powder is hindered. For this reason, there is a problem in that toner is attached to the non-image portion due to low-charged or uncharged toner, and density unevenness in the image portion occurs.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an image forming apparatus capable of surely separating and removing paper dust from a developer.

[0008]

In order to achieve this object, an image forming apparatus of the present invention comprises a developer image carrier carrying a developer image on its surface, and a transfer member for transferring the developer image onto a transfer sheet. And a cleaning member on which paper dust separated from the transfer paper adheres to the surface, and a cleaning member provided in proximity to or in contact with the cleaning member, and a potential difference between the cleaning member surface and the cleaning member surface. Is provided.

Further, the surface of the cleaning member of the present invention may be formed with an insulating layer at a portion close to or in contact with the member to be cleaned. Further, the triboelectrification polarity of the insulating layer with respect to the paper dust is determined by the paper dust. Can be elected so as to have the same polarity as the surface potential of the transfer member.

Further, the surface of the cleaning member of the present invention can be moved with respect to the contact portion or the proximity portion by forming the proximity portion or the contact portion with the member to be cleaned with a conductive layer or a semiconductive layer. .

It is also possible to provide a paper powder charging means for charging the paper powder.

[0012]

With this structure, an electric field is formed in the proximity or abutment between the member to be cleaned and the cleaning member, so that the paper dust charged with the opposite polarity to the toner is attracted to the surface of the cleaning member by the electric field force. , And can be removed separately from the toner. Further, by forming the surface of the cleaning member with an insulating layer, it is possible to prevent the charge polarity of the paper powder from changing due to the injection of charges from the surface of the cleaning member. By selecting the same polarity as the electric potential, it is possible to prevent the change in the charging polarity of the paper dust due to contact and friction with the surface of the cleaning member, so that the paper dust can be reliably captured on the surface of the cleaning member. If the surface of the cleaning member is a conductive layer or a semi-conductive layer,
The charge polarity of paper dust changes due to the charge injection from the cleaning member surface, but the paper dust is transported and collected from the field of action of the electric field by moving on the cleaning member surface. It is possible to prevent redeposition. Further, by providing the paper powder charging means for charging the paper powder, it is possible to uniformly charge the paper powder that is low-charged or uncharged after the transfer and surely removes it by the action of the electric field force. Therefore, even when the developer is repeatedly used, the mixture of paper powder is prevented, and thus it is possible to prevent the image defect due to the deterioration of the charging property of the developer and the blocking of the developer flow path.

[0013]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view of an image forming apparatus according to the first embodiment of the present invention. In FIG. 1, 10 is a latent image carrier which is a member to be cleaned, 11 is a latent image carrier charging member, 12 is laser light modulated according to an image signal, and 13 is a surface on which a uniform developer layer is carried. A developer carrier to which a predetermined voltage is applied, 14 is a transfer sheet, 15 is a transfer member, and 16 is a paper dust removing member for removing the paper dust on the latent image carrier 10, which is made of an electrically conductive material coated with insulation. It is grounded via a power source (not shown) and is close to the latent image carrier 10 with a potential difference. Reference numeral 17 denotes a toner collecting device including a cleaning blade 17a, a waste toner casing 17b, and a toner conveying means 17c.

The operation of the image forming apparatus configured as described above will be described with reference to FIGS. 1, 2 and 3.

First, as shown in FIG. 1, the surface of the latent image carrier 10 is uniformly negatively charged by the latent image carrier charging member 11, and an electrostatic latent image is formed by exposure to the laser beam 12.

The negatively charged developer layer carried on the surface of the developer carrying member 13 develops the electrostatic latent image by the electric field formed between the latent image carrying member 10 and the developer carrying member 13, A developer image is formed on the latent image carrier 10.

On the other hand, the transfer sheet 14 conveyed to the nip portion between the latent image carrier 10 and the transfer member 15 by a conveying means (not shown) is charged to the positive polarity by the transfer member 15 and therefore is transferred to the latent image carrier 10. An electric field is formed between them, and the negatively charged developer image is transferred to the transfer paper 14.

The toner remaining after the transfer is scraped off by the cleaning blade 17a as the latent image carrier 10 rotates, is housed in the waste toner casing 17b, and is sequentially transported by the toner transport means 17c through a toner flow path (not shown). , Is carried again on the developer carrier 13.

On the other hand, at the time of transfer, paper fibers such as paper fibers and filler separated from the transfer paper 14 adhere to the surface of the latent image carrier 10. The transfer paper 14 is positively charged by the transfer member 15, so that the paper dust is positively charged.

The paper dust reaches a portion near the paper dust removing member 16 where an electric field is formed as the latent image carrier 10 rotates, and is attracted to the surface of the paper dust removing member 16 by the electric field force. . On the other hand, since the toner is negatively charged, it remains bound to the surface of the latent image carrier 10.

FIG. 2 shows an electric field formed in the gap when the paper dust removing member 16 in FIG. 1 is formed only by the conductive layer 16b (FIG. 2a) and when the insulating layer 16a is provided on the surface (FIG. 2b). FIG. 4 is a schematic diagram showing the result of observing the behavior of paper powder.

In FIG. 2a, the paper powder sucked from the surface of the latent image carrier 10 receives charge injection from the surface of the conductive layer 16b and is recharged to the same polarity as the voltage applied to the conductor, and after a certain time the action of the electric field. Upon receipt, it reattaches to the surface of the latent image carrier 10. On the other hand, in FIG. 2b, the paper dust sucked by the insulating layer 16a is not subjected to charge injection, and further, the triboelectrification polarity of the insulating layer 16a is the reverse polarity of the toner due to the friction of the transfer paper 14 with the insulating layer 16a (this embodiment If the charging is selected to be positively charged in the example), the reverse charging of the paper dust can be prevented, and the paper dust can be reliably bound to the surface of the paper dust removing member 16.

Therefore, in this embodiment, in order to prevent recharging of the paper dust, the surface of the paper dust removing member 16 is formed of an insulating layer such as a fluorine resin.

FIG. 3 shows the latent image carrier 10 and the paper dust removing member 1.
6 is a diagram showing the potential difference and the removal rate of paper dust when the gap in the vicinity of 6 is 200 μm. As the potential difference increases, the large-sized paper dust is sucked by the paper dust removing member 16, and the removal rate increases.

As described above, since the electric field is formed in the vicinity of the paper dust removing member 16 and the latent image carrier 10, the paper dust charged on the latent image carrier 10 by being charged with the opposite polarity to the toner. To
It can be separated by suction and removed by suction.

Further, since the surface of the paper dust removing member 16 is formed of an insulating layer, recharging of the paper dust due to charge injection from the surface of the paper dust removing member 16 and discharge when the electric field strength in the vicinity is increased. This can be prevented, and the paper dust can be reliably sucked and removed by the surface of the paper dust removing member 16.

(Embodiment 2) A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is a schematic sectional view of an image forming apparatus according to the second embodiment of the present invention. In FIG. 4, 10 is a latent image carrier, 11 is a latent image carrier charging member, 12 is a laser beam, 13 is a developer carrier, 14 is a transfer sheet, 15 is a transfer member, and 17 is a toner collecting device. Is similar to that of FIG. The difference from the configuration of FIG. 1 is that the paper dust removing member 16 is formed of a roller-shaped rotating body having a conductive or semi-conductive surface, and a cleaning member 18 is further provided on the surface of the paper dust removing member 16. A paper dust accommodating casing 19 is provided behind the cleaning member 18 in pressure contact.

The operation of the image forming apparatus configured as described above will be described with reference to FIG.

First, as in the case of FIG. 1, the transfer to the transfer paper 14 is performed following the formation of a developer image by charging, exposure, and development, and at the same time as the transfer, the paper dust separated from the surface of the transfer paper 14 is a latent image carrier. Adhere on 10.

The paper dust removing member 16 rotates in the same direction as the latent image carrier 10 at a predetermined speed and applies a predetermined voltage to form an electric field in the vicinity of the latent image carrier 10. The paper dust on the surface of the latent image carrier 10 is attracted to the surface of the paper dust removing member 16 by the electric field formed in the vicinity. As shown in FIG. 2A, the paper dust receives charge injection from the surface of the paper dust removing member 16, but in order to recharge the paper dust and start re-flying to the latent image carrier 10, It takes 1 to 2 seconds. In the present embodiment, the paper dust is conveyed with the rotation of the paper dust removing member 16, so that it is out of the range where the electric field force of the proximity portion acts at the time of recharging. Therefore, the paper dust once sucked and removed from the latent image carrier 10 is carried on the surface of the paper dust removing member 16, scraped off by the cleaning member 18, and housed in the paper powder housing casing 19.

In this embodiment, an aluminum roller is used as the paper dust removing member 16, and the peripheral speed is set so that the paper dust once captured does not recharge and return to the latent image carrier 10.

Even when the surface of the paper dust removing member 16 is made conductive or semiconductive as described above, the paper dust removing member 16 is also provided.
It is possible to collect the paper dust by moving the surface of the sheet from a portion close to the latent image carrier 10 and prevent reattachment to the latent image carrier 10 due to recharging of the paper dust. Therefore, the paper dust can be reliably separated from the toner, and it is not necessary to form an insulating layer on the surface, and the paper dust removing member 16 can have a simple structure.

(Embodiment 3) A third embodiment of the present invention will be described below with reference to the drawings.

FIG. 5 is a schematic sectional view of an image forming apparatus according to the third embodiment of the present invention. In FIG. 5, 10 is a latent image carrier, 11 is a latent image carrier charging member, 12 is a laser beam, 13 is a developer carrier, 14 is a transfer sheet, 15 is a transfer member, 16 is a paper dust removing member, 17 Is a toner collecting device,
The above is the same as the configuration of FIG.

The difference from the configuration of FIG. 1 is that the paper dust removing member 1
6, the latent image carrier 1 is provided on the upstream side in the rotation direction of the latent image carrier 10.
The point is that the paper dust charging member 20 that positively charges the paper dust attached to the surface of No. 0 is provided. The paper dust charging member 20 is formed of a plate-shaped blade whose surface is conductive or semi-conductive, and is provided in contact with the surface of the latent image carrier 10 by applying a voltage having the same polarity as that of the transfer member 15 by a power source (not shown). Has been.

The operation of the image forming apparatus configured as described above will be described with reference to FIG.

First, as in the case of FIG. 1, the transfer to the transfer paper 14 is performed following the formation of a developer image by charging, exposure, and development, and at the same time as the transfer, the paper dust separated from the surface of the transfer paper 14 is a latent image carrier. Adhere on 10.

The transfer residual toner and paper dust are collected by the latent image carrier 10.
Reaches the contact portion with the paper dust charging member 20,
The paper dust is uniformly positively charged by the paper dust charging member 20. Since the surface of the toner is covered with the insulating layer, charge injection is not performed and the charge polarity does not change.

Therefore, the paper dust is reliably separated and removed from the toner by the electric field formed in the vicinity of the paper dust removing member 16 and the latent image carrier 10.

As described above, the uncharged paper powder mechanically adhered to the surface of the latent image carrier 10 at the time of transfer, the low charged paper powder, or the negatively charged reversely charged paper powder is also the paper powder charging member 20. Since it is uniformly charged with the opposite polarity to the toner, the electric field formed by the paper dust removing member 16 can reliably separate and remove the toner.

In this embodiment, the paper dust charging member 2
0 is composed of a stationary member in contact with the latent image carrier 10,
It is also possible to use a rotating body whose surface is made of conductive rubber or the like.

Since the paper fibers have a size several times to several tens of times larger than the average particle size of the toner, the paper powder charging member 2
The same effect can be obtained by placing 0 near the latent image carrier 10 and bringing it into contact with only the paper dust, and the present invention is not limited to the configuration of this embodiment.

In this embodiment, the latent image carrier 10 is used as the member to be cleaned, which is applied to the electrophotographic image forming apparatus, but any member may be used as long as the paper dust adheres to the surface thereof. Similar effects can be obtained in an image forming apparatus that does not use a photographic method.

(Embodiment 4) A fourth embodiment of the present invention will be described below with reference to the drawings.

FIG. 6 is a schematic sectional view of an image forming apparatus according to the fourth embodiment of the present invention. 6, 10 is a latent image carrier, 11 is a latent image carrier charging member, 12 is a laser beam, 13 is a developer carrier, 14 is a transfer sheet, 15 is a transfer member, and the above is the same as the configuration of FIG. belongs to. The difference from the configuration of FIG. 1 is a roller-shaped rotating body having a conductive or semi-conductive and adhesive surface, for example, the surface is formed of silicone rubber or the like, and has the same polarity as the transfer member 15 by a power source (not shown). A collecting member 21 provided by applying a voltage to the latent image carrier 10 under pressure contact, and a paper dust removing member 1 provided downstream of the collecting member 21 of the latent image carrier 10 in the rotation direction.
6 and a developer recovery device 17 provided on the downstream side of the recovery member 21 in the rotation direction.

The operation of the image forming apparatus configured as described above will be described with reference to FIG.

First, as in the first embodiment, charging, exposure, and
Transfer to the transfer paper 14 is performed following the development of the developer image, and at the same time as the transfer, the paper dust separated from the surface of the transfer paper 14 adheres to the latent image carrier 10.

The transfer residual developer and paper dust are transferred to the latent image carrier 10.
With the rotation of, it reaches the contact portion with the collecting member 21 and adheres to the surface of the collecting member 21 due to the adhesiveness of the surface of the collecting member 21. The electric charge of the paper dust is injected from the surface of the collection member 21 before reaching the vicinity of the paper dust removal member 16, and is uniformly charged with the opposite polarity to the toner, and the toner has the surface covered with an insulating layer. Therefore, the charge injection is not performed and the charging polarity does not change.

Therefore, when the paper dust reaches the vicinity of the paper dust removing member 16, the paper dust removing member 16 and the collecting member 2
The toner is surely separated and removed from the toner by the electric field formed in the vicinity of 1, and the toner is collected by the toner collecting device 17 and carried again on the developer carrier 13.

As described above, according to this embodiment, the uncharged paper powder mechanically attached to the surface of the latent image carrier 10 at the time of transfer is also charged to the opposite polarity to the toner by the collecting member 21, so that the electric field force is increased. By this, it is possible to reliably separate and remove the toner. Further, since the paper dust removing member 16 can be arranged independently of the latent image carrier 10, the latent image carrier 10 having a small diameter can be used.

In the first, third, and fourth embodiments, the paper dust removing member 16 includes the latent image carrier 10 or the collecting member 21.
Although the stationary member provided in the vicinity of is used, the paper dust can be collected by using a rotating body or the like, and it is also effective when it is provided in contact with the latent image carrier 10 or the collecting member 21. It is applicable and is not limited to the configuration of this embodiment.

In the second embodiment, the blade member of the cleaning member 18 is pressed against the paper dust removing member 16, but when a brush or the like is pressed or the electric field is formed by the non-contact cleaning member. Also, the paper dust removing member 16 may be formed by a belt or the like, and is not limited to the configuration of this embodiment.

Further, the image forming apparatus in this embodiment is
Although it was applied to a process in which each step of charging, exposure, development, and cleaning is performed independently, it can be effectively applied even when a part of each step is combined or omitted, and when an intermediate transfer member is used, etc. Can be effectively applied to the present invention and is not limited to the configuration of this embodiment.

Further, in the first, second, third, and fourth embodiments, only the removal of the paper dust separated from the transfer paper is described, but the insulating foreign matter charged to the opposite polarity to the toner,
Also, the same effect can be obtained for a foreign substance that behaves as conductive or semi-conductive.

Further, in the fourth embodiment, the recovery member 2
Although 1 is a roller-shaped rotating body, it can be effectively applied to the case where a belt-shaped conductive rubber or the like is used. Further, the surface of the collecting member 21 is formed of an insulating member, and A paper dust charging member may be provided on the upstream side of the collecting member 21 in the rotation direction, and the configuration is not limited to that of this embodiment.

[0058]

As described above, according to the present invention, the developer image carrier for carrying the developer image on the surface, the transfer member for transferring the developer image to the transfer paper, and the paper dust separated from the transfer paper are provided on the surface. A cleaning member that is attached to the cleaning member and a cleaning member that is provided close to or in contact with the cleaning member. By providing a potential difference between the surface of the cleaning member and the surface of the cleaning member, the toner is charged to the opposite polarity to the toner. Since the electric field force can be applied to the formed paper powder, the paper powder can be separated and removed from the toner.

Further, by forming the portion of the surface of the cleaning member which is close to or abutting the member to be cleaned with the insulating layer, the paper powder sucked by the electric field can be reliably captured.

Further, even when the surface of the cleaning member is formed of a conductive layer or a semiconductive layer, the surface of the cleaning member is moved with respect to the contact portion or the proximity portion to the member to be cleaned, so that the paper dust is recharged. It is possible to prevent the return to the member to be cleaned due to the above, and to reliably collect the paper dust.

Further, by providing the paper powder charging means,
Since the paper dust is charged in the opposite polarity to the toner, the paper dust not charged or having the same polarity as the toner can be reliably separated and removed from the toner during transfer.

As described above, according to the present invention, the paper powder can be reliably separated and removed from the toner, so that a high quality image can be obtained even when the developer is repeatedly used.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing the behavior of paper dust in the first embodiment of the present invention.

FIG. 3 is a graph showing paper dust removal characteristics of the image forming apparatus according to the first embodiment of the present invention.

FIG. 4 is a schematic sectional view of an image forming apparatus according to a second embodiment of the present invention.

FIG. 5 is a schematic sectional view of an image forming apparatus according to a third embodiment of the present invention.

FIG. 6 is a schematic sectional view of an image forming apparatus according to a fourth embodiment of the present invention.

FIG. 7 is a schematic sectional view of a conventional device.

[Explanation of symbols]

 10 latent image carrier 14 transfer paper 16 paper dust removing member 17 toner collecting device 18 cleaning member 19 paper dust containing casing 20 paper dust charging member 21 collecting member

Claims (8)

[Claims] 1. A developer image bearing member carrying a developer image on the surface thereof, and a transfer member for transferring the developer image to a transfer sheet or the like.
A cleaning member provided on the surface to which the paper dust separated from the transfer paper adheres; and a cleaning member provided in proximity to or in contact with the cleaning member, and between the cleaning member surface and the cleaning member surface. An image forming apparatus characterized in that a potential difference is provided in the image forming apparatus. 2. The surface potential V4 of the cleaning member is (V1-V2) * (V3-V4) with respect to the surface potential V1 of the developer image carrier, the surface potential V2 of the transfer member, and the surface potential V3 of the member to be cleaned. ) <0 is satisfied, the image forming apparatus according to claim 1. 3. The image forming apparatus according to claim 1, wherein the proximity portion or the contact portion of the cleaning member with respect to the member to be cleaned is formed of an insulating layer. 4. The image forming apparatus according to claim 3, wherein the triboelectrification polarity of the insulating layer with respect to the paper dust is selected so that the paper dust has the same polarity as the surface potential of the transfer member. 5. A surface of a contact portion of the cleaning member with the member to be cleaned or a surface of a proximity portion is formed of a conductive layer or a semiconductive layer, and the surface of the cleaning member is moved with respect to the contact portion or the proximity portion. The image forming apparatus according to claim 1, wherein: 6. The image forming apparatus according to claim 1, further comprising a paper dust charging unit that charges the paper dust. 7. A paper powder charging member provided in contact with a developer image carrier, wherein the surface of the paper powder charging member in contact with the developer image carrier is formed of a conductive layer or a semiconductive layer. 7. The image forming apparatus according to claim 6, wherein a potential difference is provided between the surface of the paper dust charging member and the surface of the developer image carrier. 8. A surface potential V1 of a developer image carrier and a surface potential V2 of a transfer member, and a surface potential V3 of a paper dust charging member.
The image forming apparatus according to claim 7, wherein (V1−V2) × (V1−V3)> 0 is satisfied.