JP2003195651A - Transfer device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transfer device by which excellent transfer is performed even though a transfer material is strongly curled by preventing the occurrence of defective transfer at the front end and the rear end of a transfer material in a conventional transfer device. <P>SOLUTION: This transfer device is provided with a transfer material guide to guide the transfer material to a corona discharger for transfer and a transfer auxiliary guide provided at the aperture of the housing of the corona discharger for the transfer so as to partially or wholly cover it by bringing the transfer material guided by the transfer material guide into contact with an image carrier. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device in an image forming apparatus using an electrophotographic system.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus using an electrophotographic system, which is embodied by a copying machine, a printer or the like, has been known. When forming an image by electrophotography,
In order to transfer the toner image from the image bearing member carrying the toner image onto the transfer material, the transfer bias is applied through the transfer material passing through the transfer portion, that is, from the back side of the transfer material by a corona discharger or a charging roller. Application is performed, and the toner image on the image carrier is electrostatically attracted to the transfer material side to perform transfer. Further, in such a transfer device, in order to prevent the transfer image of the toner image from being omitted, that is, before transferring to the transfer portion for performing good transfer evenly on the entire surface of the transfer material, the transfer material is firmly attached to the surface of the image carrier. In addition, it is necessary to adhere them uniformly.

[0003]

However, particularly when thick roll paper or the like is used as the transfer material to form an image,
In the conventional apparatus, due to the stiffness of the transfer material or the curl strength peculiar to the roll paper, the front end and the rear end of the transfer material do not come into close contact with the image carrier. Even if good transfer is achieved by firmly adhering the front edge to the image carrier, the rear edge of the transfer material does not completely adhere, that is, the image is missing without good transfer. Was sometimes. Furthermore, when such thick roll paper runs short and near the core,
Since the transfer material has a very strong curl, it is particularly likely to cause transfer failure. Usually, the transfer material is fed in such a direction that the curl does not wind around the image carrier, that is, the back side of the curl is in contact with the image carrier. In order to bring the image into close contact with the body to transfer the image, a large amount of energy such as charging is required to attract the front end and the rear end of the transfer material to the image carrier. Especially, in the electrostatic transfer by the transfer corona, the energy for charging is limited,
In such a poor adhesion state, there is a problem in that image dropouts or transfer defects occur at the front end and the rear end side, and as a result, the effective image range of the transfer material is narrowed.

The present invention provides a transfer device capable of preventing a transfer defect at the front end and the rear end of a transfer material in a conventional transfer device and performing good transfer even with a transfer material having a strong curl.

[0005]

In order to solve the above problems, a transfer material guide for guiding a transfer material to a transfer portion and a part or a part of the transfer material guided by the transfer material guide are brought into contact with an image carrier. It is characterized in that it has a transfer assisting member provided so as to cover the entire transfer portion.

Further, the transfer portion is a corona discharger, the transfer auxiliary member is provided without a step at a position downstream of the transfer material guide, and a part or a part of the transfer auxiliary member is provided in an opening of a housing of the corona discharger. It is characterized in that it is arranged so as to cover the whole.

Further, the transfer assisting member is characterized by having a comb shape having a base portion and a rod-shaped guide portion.

In particular, the transfer assisting member is arranged so as to hold a gap of 0.8 mm or less from the surface of the image carrier.

Further, in particular, a plurality or one of the transfer assisting members are arranged at appropriate intervals in the width direction of the transfer portion, and the rod-shaped guide portions are slanted from the rear to the front along the transfer material conveying direction. The transfer material is arranged so as to be inclined toward the center line side in the width direction of the transfer material.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described with reference to the drawings. First, as the transfer material used in the present invention, roll paper or cut paper may be used, but especially roll paper in which the stiffness remains strong and the curl becomes strong due to the core, or thick paper It is also effective for transfer materials that originally have strong curls. With reference to FIG. 1, each part of the transfer path and the transfer device will be described according to the transfer material supply direction (flow) B. In the figure, reference numeral 1 denotes an image carrier, which is an electron in which a photosensitive layer made of an organic photoconductor of copper phthalocyanine or an inorganic photoconductor of selenium is applied or vapor-deposited on the surface of a substrate made of a metal such as aluminum. It consists of a photoconductor and rotates in the direction of arrow A. In this example, the image carrier 1 has a drum shape, but may have an endless belt shape.

Although not shown, a static eliminator such as an eraser lamp and a surface of the image carrier 1 around the image carrier 1 in order to electrostatically neutralize the image carrier 1 in accordance with the rotation direction A thereof. A charger such as a corona charger or a charging roller for uniformly charging the surface of the image carrier 1 with a specific polarity, or a laser or L to form a desired electrostatic latent image on the surface of the charged image carrier 1.
An exposure device for providing optical information by an ED or the like and a developing device for forming an image with toner powder, which is a charged powder, are sequentially provided on the surface of the image carrier 1.
The rotation is sequentially performed on the image carrier 1. As the image carrier 1 and the above-mentioned devices around the image carrier 1, the same configuration as that of each part of an image forming apparatus using a well-known electrophotographic system can be used except for a transfer device.

In the figure, reference numeral 2 is a transfer material guide for guiding the transfer material conveyed from the paper feeding section to the transfer section 10 along the upper surface thereof, and further downstream of the transfer material guide 2, there is further below the transfer material. A preliminary guide 3 is provided to prevent falling in the direction. The preliminary guide 3 may be omitted if the transfer material guide 2 can sufficiently guide the transfer material to the transfer portion 10.

Next, reference numeral 4 in the drawing denotes a downstream position of the transfer material guide 2 or, when the auxiliary guide 3 is provided, an auxiliary guide 3
Is a transfer auxiliary guide that is provided at a downstream position of the transfer medium without a step in the flow direction of the transfer material and firmly adheres the transfer material to the image carrier 1 to the front end and the rear end thereof. The transfer assist guide 4 is, as shown in FIGS. 2 and 3,
It has a comb-like shape as a whole, and is composed of a base portion 12 and a rod-shaped guide portion 11 protruding from the base portion 12 and extending substantially parallel to the image carrier 1. With the comb-like shape, the rod-shaped guide portion 11 does not block the discharge energy of the corona discharger 5 for transfer, thereby uniformly and efficiently charging, and further the rod-shaped guide portion 11
Is inclined in the central direction from diagonally rearward to frontward along the transfer material conveying direction (in this embodiment, the inclination angle is 30 degrees with respect to the base 12 of the transfer material, but is not limited to this). , And the tip of the rod-shaped guide portion 11 is arranged at a position where the wire of the transfer corona discharger 5 is not hidden (preferably about 1 mm immediately before the wire). The transfer unevenness such as a net trace by the portion 11 (partial transfer failure due to a guide for preventing transfer material intrusion in a conventional transfer corona discharger) is prevented, and the transfer material is conveyed smoothly. In this embodiment, the rod-shaped guide portion 11 and the base portion 12 are integrally molded, but they may be assembled as separate members.

Further, in this embodiment, the rod-shaped guide portion 11 has a total length of 9.4 mm, and the rod-shaped guide portion 11 is arranged at an angle of about 30 degrees with respect to the base portion 12, as described above. In this embodiment, the linear distance from the tip of the rod-shaped guide 11 to the transfer corona discharger 5 is 8 mm, and the diameter or width of the rod-shaped guide portion 11 is 1.2 mm, but the present invention is not limited to this. . In the illustrated example, a plurality of individual transfer auxiliary guides 4 provided with two rod-shaped guide portions 11 are used for one base portion 12, and the position C of each transfer auxiliary guide 4 is set to the corona discharger for transfer. No. 5 is appropriately positioned with respect to the side wall of the corona housing, and is adhered or screwed or fitted along the side wall of the corona discharger 5 corona housing in parallel at an appropriate interval for conveying the transfer material. Combine and fix. As described above, in this embodiment,
Although a plurality of transfer assist guides 4 are arranged in parallel and fixed,
They may be formed as one member integrally formed in a continuous shape.

As a condition for arranging the transfer auxiliary guide 4, it is preferable to maintain a gap of 0.8 mm or less from the surface of the image carrier 1, and in this embodiment, it is particularly preferable to
The gap is set to 0.4 to 0.7 mm, and the transfer material to be conveyed can be surely contacted evenly including the front and rear ends of the transfer material so that the transfer material can be conveyed, and the image carrier 1 is scratched. There is no need for a position. Further, as the material of the transfer assisting guide 4, it is preferable to use a resin or the like that is an insulating member that withstands the weight of the transfer material and has a withstand voltage and physical strength. It is preferable to use resins such as polyphenylene ether and polycarbonate. As a result, even if the transfer material has a strong curl, the image carrier 1 does not lose the curl.
The transfer material can be closely attached to.

Referring again to FIG. 1, reference numerals 5 and 6 in the figure denote a transfer corona discharger for transferring a toner image onto a transfer material, and an image carrier 1 provided downstream of the transfer corona discharger. It is a corona discharger for separation as a transfer material separating means. In the present embodiment, when the wire in the transfer corona discharger 5 is drawn down from the center of the image carrier 1,
It is positioned within a width of plus or minus 3 mm with reference to this perpendicular line. This is to make the transfer to the rear end side of the transfer material particularly efficient, but is not limited to this, but temporarily, the wire in the transfer corona discharger 5 is connected to the entrance side of the transfer portion. If it is close to the transfer material, there will be no problem in transferring it to the leading edge side of the transfer material, but the transfer to the rear end side of the transfer material will be defective. Will result in. Further, after the transfer material passes through the transfer corona discharger 5, a voltage in which a DC voltage and an AC voltage are superimposed is applied to the transfer material by the separation corona discharger 6 to transfer the transfer material from the image carrier 1. Separate. In addition, especially when the curl of the transfer material is strong,
When the trailing end side of the transfer material is turned off when passing through the separating corona discharger 6, the transfer to the trailing end side of the transfer material is improved. As another transfer means and separation means, a so-called charging roller in which a necessary bias is applied to a conductive roller may be used.

Reference numeral 7 in the drawing is positioned so as to cover the separating corona discharger 6 from above, prevents the transfer material from entering the separating corona discharger 6, and is further separated from the image carrier 1. It is a thin corona discharger guide 7 for separation that guides the transfer material to the next step. Separation Corona Discharger Guide 7
Covers the upper opening of the separating corona discharger 6, and
The transfer corona discharger 5 is arranged so as to overlap with the transfer corona discharger 5, and the transfer corona discharger 5 is arranged at a length of 1 mm or more from the wire of the transfer corona discharger 5. The separating corona discharger guide 7 is provided so as to be fitted on the side wall of the separating corona discharger 6 in this embodiment, but may be fixed by adhesion or screws.

Further, an opening is formed in the bottom surface of the separation corona discharger 6, and a separation assisting lamp 9 is formed under the opening.
Is located. When the transfer material passes through the separation corona discharger 6, the transfer material is separated from the image carrier 1 and at the same time, the charge is removed, and the image carrier 1 after the transfer material is separated from the image carrier 1 is removed.
Is removed by the separation assisting lamp 9. The separation assisting lamp 9 can be omitted if necessary. When the separation assisting lamp 9 is provided, when a transfer material having a weak curl or stiffness is used, it may be always on, but when a curl of the transfer material itself or a transfer material having a stiffness is used. By turning off the separation assisting lamp 9 during the transfer to the rear end side of the transfer material, the transfer to the rear end side of the transfer material can be performed more efficiently. Reference numeral 8 in the drawing denotes a conveyor belt for conveying the transfer material, to which the electrostatic latent image separated from the image carrier 1 is transferred, to a fixing device (not shown).

Next, a more specific embodiment of the present invention will be described. In this embodiment, the polarity of the toner is negative, and the separation corona discharger 6 has about 13 kV _PP.
A voltage in which a DC voltage of approximately -250V is superimposed on the AC voltage of is applied to the transfer corona discharger 5 of 6 to 6.5kV.
Although the DC voltage is applied, the value is not limited to this value and is set to an appropriate value for transferring and separating the transfer material. First, the above-described roll paper is used as a transfer material, and the transfer material fed from a paper feeding unit (not shown) is guided to the transfer unit 10 by the transfer material guide 2 and the preliminary guide 3. At this time, when the trailing edge of the transfer material passes through the transfer material guide 2, a rear end portion of the transfer material is detected by a sensor (not shown) provided near the transfer material guide 2, and the signal is emitted to the corona for separation. It is sent to the on / off control unit (not shown) of the electric appliance 6 and the separation assisting lamp 9. As a result, when the trailing end side of the transferred transfer material passes through the separating corona discharger 6, the control unit turns off the separating corona discharger 6 so that the image on the trailing end side of the transferring material is separated. Disturbance can be prevented. Further, the separation assist lamp 9 is turned off at the same time as the separation corona discharger 6 so that the image is not disturbed further.

The transfer material is completely transferred to the image carrier 1 by the transfer auxiliary guide 4 provided just before the transfer member 10 is projected into the transfer portion 10.
And the image carrier 1 is brought into close contact with the image carrier 1 and good transfer as described above is performed by the transfer corona discharger 5. After the transfer is completed, the transfer material that was in contact with the image carrier 1 at the time of transfer is separated by the separation corona discharger 6 in order to separate it from the image carrier 1, and depending on the transfer material, the rear end side of the transfer material. Is turned off in order to transfer the data efficiently. In this way, the transfer material separated from the image carrier 1 by the separating corona discharger 6 is conveyed by the conveying belt 8 to a fixing device (not shown), undergoes a fixing process, and is then discharged to the outside of the image forming apparatus. To be done.

[0021]

According to the present invention, by providing the transfer auxiliary guide immediately before the transfer portion, the leading end side and the trailing end side of the transfer material can be evenly adhered to the image carrier, and the transfer can be performed. It is possible to perform the charging uniformly, and it is possible to efficiently apply the charge during the transfer without fear of uneven transfer such as a net mark due to the transfer assist guide.

[Brief description of drawings]

FIG. 1 is a schematic side view showing a transfer device according to the present invention.

2A and 2B are a plan view and a side view of a transfer auxiliary plate according to the present invention.

FIG. 3 is a plan view of a transfer portion with a transfer auxiliary plate attached thereto according to the present invention.

[Explanation of symbols]

1 Image carrier 2 Transfer material guide 3 preliminary guide 4 Transfer assist guide 5 Transfer corona discharger 6 Corona discharger for separation 7 Corona Discharger Guide for Separation 8 conveyor belt 9 Separation assistance lamp 10 Transfer part 11 Bar-shaped guide 12 base

Claims (5)

[Claims] 1. A transfer material guide for guiding the transfer material to the transfer portion, and a part or all of the transfer material guide so as to contact the transfer material guided by the transfer material guide with the image carrier. A transfer device having a transfer assisting member. 2. The transfer section is a corona discharger, the transfer auxiliary member is provided at a position downstream of the transfer material guide without a step, and a part or a part of the transfer auxiliary member is provided in an opening of a housing of the corona discharger. The transfer device according to claim 1, wherein the transfer device is arranged so as to cover the whole. 3. The transfer device according to claim 1, wherein the transfer assisting member has a comb shape having a base portion and a rod-shaped guide portion. 4. The transfer device according to claim 1, wherein the transfer assisting member is arranged so as to maintain a gap of 0.8 mm or less from the surface of the image carrier. 5. A plurality or one of the transfer assisting members are arranged at appropriate intervals in the width direction of the transfer portion, and the rod-shaped guide portions are transferred from diagonally rearward to frontward along the transfer material conveying direction. The transfer device according to claim 1, wherein the transfer device is arranged so as to be inclined toward the center line side in the width direction of the material.