JP2003241527A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To separate transfer material from a transfer material carrier without causing irregularities in an unfixed toner image on the transfer material carried on the transfer material carrier. <P>SOLUTION: In the image forming apparatus, a toner image is transferred to the transfer material carried and fed on the transfer material carrier, and the apparatus is equipped with a separation electrifying means divided in a width direction being a perpendicular direction to the feeding direction of the transfer material so as to separate the transfer material from the transfer material carrier, and then such separation is performed based on image information. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION

2. Description of the Related Art As shown in FIG. 7, a transfer material 3 is carried on a surface of a transfer material carrier 2 such as a transfer drum or a transfer belt which is in contact with the image carrier 1 and conveyed, and the image carrier is carried based on image information. 1
There is a multiple transfer system in which four color toner images sequentially formed on the transfer material 3 are electrostatically transferred from the image carrier 1 onto the transfer material 3 and are sequentially superposed and transferred.

In the case of this multiple transfer system, there is an example in which the transfer material 3 is electrostatically adsorbed to the transfer material carrier 2 and transferred in order to stably transfer the transfer material without color shift. When the multiple transfer is completed, the transfer material 3 is separated from the transfer material carrier 2 and conveyed to the fixing unit 4, where the toner is fused and fixed to the transfer material 3.

By the way, the transfer material 3 separated from the transfer material carrier 2 in the above-mentioned process is charged by the image carrier 1 when the toner image is transferred. When the transfer material 3 thus charged is separated from the surface of the transfer material carrier 2, peeling discharge is generated between the transfer material 3 and the transfer material carrier 2, and the unfixed toner on the transfer material 3 is scattered. May cause a defective image.

As a countermeasure against this problem, a known corona discharge separation charger 6 is disposed near the separating portion between the transfer material 3 and the transfer material carrying member 2 to cause corona discharge above the transfer material so that the transfer material It is often used to employ a separation charge removal method that removes charges by separating them.

[0005]

However, if the separation charger 6 removes electric charges too much, the adhesion of the unfixed toner image to the transfer material is weakened too much and the transfer material is fixed after being separated from the transfer material carrier. Image defects such as tailing and scattering of the unfixed toner image occur before being conveyed to the unit. On the other hand, if the charge removal by the separation charger 6 is weak, peeling discharge occurs when the transfer material is separated from the transfer material carrier, and unfixed toner is scattered.

The phenomenon described above differs depending on the amount of toner, that is, the image density. FIG. 5 is a diagram in which the width direction perpendicular to the transfer material conveyance direction is viewed from the upstream or downstream side of the transfer material conveyance direction. It will be described with reference to FIG. 5 that the occurrence status varies depending on the image density. As shown in FIG. 5, due to the resistance of the toner itself, the amount of transfer current flowing where the image density is high is smaller than the amount of transfer current flowing where the image density is low. That is, the amount of charge on the transfer material is small where the image density is high on the transfer material after transfer, and the amount of charge on the transfer material is large where the image density is low. Therefore, as shown in FIG. 6, if one attempts to separate the transfer material from the transfer material carrier 2 with one separation charge-eliminating output a, the charge is excessively removed at a place where the image density is high, and conversely at a place where the image density is low. The charge removal is too weak, and it is difficult to eliminate image defects over all densities.

[0007]

An image carrier, and an image forming unit for forming a toner image according to image information on the image carrier,
A transfer charging unit that is arranged to face the image carrier via a transfer material carrier that carries a transfer material, and that electrostatically transfers the toner image to the transfer material by applying a charge having a polarity opposite to that of the toner; In an image forming apparatus including means for separating the transfer material carrying an unfixed toner image after transfer and the transfer material carrying member, the transfer material is divided into the transfer material and the transfer material by dividing the transfer material in a width direction perpendicular to a transfer material conveying direction. An image forming apparatus comprising: a separating unit that separates a transfer material carrier, and that separates based on the image information.

An image forming apparatus in which the separating means is a roller and a needle electrode which are divided in a width direction perpendicular to a transfer material conveying direction.

An image forming apparatus, wherein a bias is controlled and applied to the separating means based on the image information.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) FIG.
About.

FIG. 2 is a schematic configuration diagram of an electrophotographic image forming apparatus showing an embodiment of the present invention. In the figure, reference numeral 8 is a charging device, 7 is exposure for carrying image information, 9 is a developing device, Reference numeral 10 is a transfer charger, and 6 is a roller which is divided into 128 parts at a distance of 2.5 mm in the transfer material horizontally and perpendicularly to the transfer material conveying direction as shown in FIG. A separation charger that removes the charge of the transfer material when applied and weakens the electrostatic attraction between the transfer material and the transfer material carrier. As the material of the base material of the roller of the separation charger 6,
Rubber materials such as isoprene rubber, styrene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, butyl rubber, silicone rubber, chloropyrene rubber, chlorosulfonated polyethylene, acrylic rubber, hydrin rubber, urethane rubber, fluororubber, or a combination thereof. Synthetic rubber or synthetic resin such as nylon, urethane, polyester, etc. mixed with a conductive agent such as tin oxide or carbon black can be used, and the resistance value is 10 ³
10 to 10 ¹⁰ Ω · cm, hardness 5 to 80 degrees (JIS
Use the one of A) grade. Reference numeral 1 denotes a photosensitive drum which is an image carrier, 3 a transfer sheet, 2 a transfer material carrier, 11 a controller for controlling exposure for carrying image information, and 5 a separating claw.

In the electrophotographic image forming apparatus as shown in FIG. 2, first, the photosensitive drum 1 is uniformly charged to a negative polarity by the charging device 8. In that state, an electrostatic latent image is formed on the photosensitive drum 1 by the exposure 7.

Next, the electrostatic latent image formed on the photosensitive drum 1 by the exposure 7 is developed with the toner of the developing device 9 to obtain a toner image. Here, the developing device 9 is a developing device that performs reversal development.

The toner image formed on the photosensitive drum 1 through the respective steps in this manner is transferred to the transfer paper 3 by the transfer charger 10 whose constant current is controlled, and is conveyed to the fixing device 4 to form an image. Form.

The transfer charging system includes a non-contact charging device such as corona discharge or a contact charging device using a transfer charging member such as a blade, a roller or a brush. Since the non-contact charger is charged through the air, it is vulnerable to temperature / humidity environment changes of the atmosphere and has a problem that an image is not stably formed. On the other hand, in the contact charger, a contact transfer charging blade is used in the present embodiment because it has advantages such as high resistance to fluctuations in temperature and humidity environment and high image quality. The transfer blade member 10 is provided with a base material made of a rectangular plate-shaped conductive rubber, and a conductive electrode provided along the lower end portion to uniformly apply a voltage in the longitudinal direction of the base material. . Linear pressure of 120g / on the photosensitive drum via the recording material and the conveyor belt
Pressed in cm. The material of the base material of the transfer blade is generally isoprene rubber, styrene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, butyl rubber, silicone rubber, chloropyrene rubber, chlorosulfonated polyethylene, acrylic rubber, hydrin rubber, urethane rubber, A rubber material such as fluororubber, a synthetic rubber obtained by compounding them, or a synthetic resin such as nylon, urethane or polyester mixed with a conductive agent such as tin oxide or carbon black can be used. 10 ³ to 10 ¹⁰ Ω · cm, hardness 5
The blade member 10 was used by using a blade having a thickness of about 80 degrees (JIS A) and setting the thickness of the base material to about 2 mm. The transfer blades used are connected to a transfer high-voltage power supply (not shown).

In the image forming apparatus of this embodiment, when the transfer material 3 passes through the separation charger, the optimum bias applied to each divided roller electrode of the separation charger of FIG. 1 passes through each roller electrode. It changes at any time depending on how the color toner layers are laminated on the transfer material. The optimum bias applied to each divided roller electrode of the separation charger is measured as follows.

The developing device 9a is Y (yellow), and 9b is M.
(Magenta), 9c contains C (cyan), and 9d contains k (black) toner. The combination of the laminated color toner layers is as shown in FIG. All the solids of the laminated color toner layers shown in FIG. 3 are transferred to the transfer material, and the bias applied to each roller electrode of the separation charging device is set to the same value so that the unfixed full solid toner image on one transfer material 3 is formed. While being fixed, the bias that separates from the transfer material carrier 2 is measured optimally without causing image disturbance due to peeling discharge, scattering of toner during conveyance of the transfer material to the fixing unit, and tailing. In this way, when the color toner layer laminated on the transfer material passes through each roller of the separation charger, the optimum bias to be applied to each roller can be known.

As shown in FIG. 3, since there are 16 combinations of toner layer stacking, one transfer material is separated by the separation charger 6.
The optimum bias applied to one of the divided roller electrodes of the separation charger while passing through is 16 types (V1 to V1) at the maximum.
6) Yes.

The combination of the lamination of the toner layers when the transfer material passes through the separation charger can be known from the image information. In the case of a laser printer method, the image information is binarized, and from the bitmap data of the controller that controls the writing device, when the transfer material passes through the separation charger, at what timing which toner layer is stacked See if the combination passes through each roller electrode of the separate charger.
That is, the bit map data is set to a certain sampling interval s
Detect by sampling every [s]. Based on this result, the bias applied to each roller electrode of the separation charger is changed at any time.

Therefore, the charge of the transfer material can be optimally removed by changing the applied bias at each roller electrode based on each image passing through each roller electrode divided in the thrust direction. The transfer material can be optimally separated from the body.

(Second Embodiment) FIG. 4 shows a fourth embodiment.

FIG. 2 is a schematic configuration diagram of an electrophotographic image forming apparatus showing one embodiment of the present invention. In the figure, reference numeral 8 is a charging device, 7 is exposure for carrying image information, 9 is a developing device, 10 is a primary transfer charger, 13 is an intermediate transfer belt, 6
1 is a roller divided into 128 at 2.5 mm intervals in the direction perpendicular to the transfer material conveying direction as shown in FIG. 1, and the high voltage is applied to each of the divided rollers to eliminate the charge of the transfer material. A separate charging device that weakens the electrostatic attraction between the transfer material and the transfer material carrier. As the material of the base material of the roller of the separation charger 6, isoprene rubber, styrene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, butyl rubber, silicone rubber, chloropyrene rubber, chlorosulfonated polyethylene, acrylic rubber, hydrin rubber,
A rubber material such as urethane rubber or fluororubber, or a synthetic rubber obtained by compounding them, or a synthetic resin such as nylon, urethane, or polyester mixed with a conductive agent such as tin oxide or carbon black can be used. A material having a resistance value of about 10 ³ to 10 ¹⁰ Ω · cm and a hardness of about 5 to 80 degrees (JISA) is used. 1 is a photosensitive drum as an image carrier, 12 is a secondary transfer charger, 3 is transfer paper,
Reference numeral 2 is a transfer material carrier, 11 is a controller that controls exposure for carrying image information, and 5 is a separation claw.

In the electrophotographic image forming apparatus as shown in FIG. 4, first, the photoconductor drum 1 is uniformly charged to a negative polarity by the charging device 8. In that state, an electrostatic latent image is formed on the photosensitive drum 1 by the exposure 7.

Next, the electrostatic latent image formed on the photosensitive drum 1 by the exposure 7 is developed with the toner of the developing device 9 to obtain a toner image. Here, the developing device 9 is a developing device that performs reversal development.

The toner image formed on the photosensitive drum 1 through the respective steps in this manner is primary-transferred onto the intermediate transfer belt 13 by the primary transfer charger 10, and the toner image on the intermediate transfer belt is further transferred. Is transferred onto the transfer paper 3 by the secondary transfer charger 12 and conveyed to the fixing device 4 to form an image.

In the image forming apparatus according to the present embodiment, when the transfer material 3 passes through the separation charger, the optimum bias setting method applied to each divided roller electrode of the separation charger of FIG. This is the same as the setting method described with reference to FIG.

[0027]

As described above, according to the present invention, when the transfer material on which the toner images of a plurality of colors are transferred is separated from the transfer material carrier, the transfer material is properly separated from the transfer material carrier and peeling discharge. For prevention, there is a separation charger divided in the width direction perpendicular to the transfer material conveyance direction, and bias is controlled and applied to each of the divided separation chargers based on image information. Can optimally eliminate the electric charge of
It is possible to prevent the image from being disturbed due to the peeling discharge at the time of separating the transfer material, and the scattering and the tailing of the toner during the transfer of the separated transfer material.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a divided transfer charger according to the present invention.

FIG. 2 is a diagram for explaining the first embodiment of the present invention.

FIG. 3 is a diagram for explaining the first embodiment of the present invention.

FIG. 4 is a diagram for explaining a second embodiment of the present invention.

FIG. 5 is a diagram for explaining a problem.

FIG. 6 is a diagram for explaining a problem.

FIG. 7 is a sectional view of a conventional image forming apparatus.

Continued front page    F-term (reference) 2H027 DA09 DA32 DB01 DE04 DE07                       EA03 EB04 EC06 EC07 EC18                       ED17 ED24 EE01 ZA07                 2H200 FA05 FA06 FA18 GA03 GA12                       GA23 GA34 GA40 GA44 GA47                       GB22 GB25 HA02 HA12 HA28                       HB02 HB12 HB14 HB40 HB45                       HB46 HB47 HB48 JA02 JA25                       JA26 JA27 JB06 JC03 KA03                       KA07 KA25 KA26 KA27 KA28                       KA29 MA03 MA04 MA13 MA14                       MA20 MB02 MB04 MC02 NA03                       PA02 PA10 PA12 PA18 PA22                       PB12 PB13 PB18 PB29 PB38

Claims (3)

[Claims] 1. An image carrier, an image forming unit for forming a toner image according to image information on the image carrier, and a transfer material carrier for carrying a transfer material, and facing the image carrier. A transfer charging unit that electrostatically transfers the toner image to a transfer material by providing an electric charge having a polarity opposite to that of the arranged toner, the transfer material that carries an unfixed toner image after transfer, and the transfer material carrier. In the image forming apparatus provided with a means for separating the transfer material, a separation charging means for separating the transfer material and the transfer material carrier by dividing the transfer material in the width direction perpendicular to the transfer material conveyance direction, and An image forming apparatus characterized by performing the separation based on the above. 2. The image forming apparatus according to claim 1, wherein the separating means is a roller and a needle electrode which are divided in a width direction perpendicular to the transfer material conveying direction. 3. A bias is controlled and applied to the separating means based on the image information.
The described layer forming apparatus.