JPH07319298A - Transfer device in image forming apparatus - Google Patents

Abstract

(57) [Summary] [Object] To simplify the installation work of the device for eliminating the static electricity of the paper P that has passed between the transfer roller 9 and the surface of the photosensitive drum 10 in the electrostatic image forming apparatus. [Structure] While a neutralization plate 33 is erected on a base plate 8a of the transfer unit base 8, a plurality of fin-shaped passage guide members 32 are erected on a horizontal plate part 8b of a support step, and the erected position The flat plate portion 34a of the auxiliary static eliminator plate 34 having a lateral L-shape in cross section is placed to avoid the above, and the auxiliary static eliminator plate 34 is fixed via the fixing means 35 at the vertical plate portion 8c of the transfer unit base 8,
The projection at the tip of the flat plate portion 34a of the auxiliary static eliminator plate 34 is attached to the static eliminator plate 33.
It is pressed against the abutting portion 36 to secure the electrical connection.

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 electrostatographic image forming apparatus such as a laser printer, a copying machine or a facsimile machine.

[0002]

2. Description of the Related Art Conventionally, for example, JP-A-4-21128
As disclosed in Japanese Patent Publication No. 7, an optical latent image is formed by applying an optical image signal to the surface of a uniformly charged photosensitive drum as an image bearing member, and charged toner is applied to the latent image. After forming the toner image, a high-voltage transfer voltage is applied to the transfer roller while passing the paper to the transfer portion where the transfer roller is in contact with the surface of the image carrier, and the toner image is transferred to the paper. An image forming apparatus is known in which a sheet is heated and pressed to fix a toner image on the sheet to form an image.

In this case, in the above-mentioned prior art, a static elimination needle is provided between the transfer portion and a conveying belt for guiding the paper coming out of the transfer portion toward the fixing device, and the electrostatic charge charged on the paper at the time of transfer is provided. It is proposed to remove the electricity.

[0004]

However, since the static elimination needle alone has a problem that the static elimination action from the paper is weak, a flat plate-shaped guide portion is provided for guiding the paper coming out of the transfer portion toward the fixing device. Was equipped with an auxiliary static eliminator. In this case, since the static elimination needle and the auxiliary static elimination plate are separately attached to the support portion and are separately grounded to the ground, it takes a lot of time to attach them, and the number of required parts is large and the manufacturing cost is high. There was a problem of becoming.

The present invention has been made to solve this problem, and it is an object of the present invention to provide a transfer device in an image forming apparatus which can be easily attached and disassembled and whose manufacturing cost can be reduced. Is.

[0006]

In order to achieve the above object, a transfer device in an image forming apparatus according to the present invention transfers a toner image onto a transfer member which faces a surface of an image carrier which rotates and carries a toner image. In an image forming apparatus configured to transfer a toner image to a recording medium such as a sheet that passes a transfer member by applying a voltage, a support portion of the transfer member and a passage guide member for the recording medium are provided upright on the surface. The transfer unit base made of the electrically insulating material is arranged on the downstream side of conveyance of the recording medium from the transfer portion, and a plate-like member having a longitudinal shape is formed between the support portion and the passage guide member along the longitudinal direction of the transfer member. The static elimination needle is erected, and the flat plate portion of the auxiliary static eliminator plate having the L-shaped cross section is placed on the upper surface of the horizontal plate portion of the support step for standing the passage guide member. Fix the plate part to the vertical part of the support step. On the other hand, it is obtained by contact with the tip end of the flat plate portion on the side surface of the charge removal needles in the auxiliary static eliminating sheet.

According to a second aspect of the present invention, in the transfer device in the image forming apparatus according to the first aspect, the side surface of the static elimination needle is abutted for electrically connecting to the tip of the flat plate portion of the auxiliary static elimination plate. It is a cut and raised part. According to a third aspect of the invention, in the transfer device of the image forming apparatus according to the first or second aspect, between the support plate portion of the transfer unit base and a plurality of fin-shaped passage guide members standing upright therefrom. In addition, a gap is formed on the downstream side of the transfer of the recording medium away from the transfer portion, and the upper surface of the horizontal plate portion of the supporting step portion and each passage guide member are provided on the tip side of the flat plate portion of the auxiliary static eliminator plate. An insertion groove is formed to avoid the root of the.

[0008]

EXAMPLES Next, examples embodying the present invention will be described. FIG. 1 is a schematic sectional side view of a laser beam printer 1 as an image forming apparatus, and FIG. 2 is a sectional side view of a transfer device. In the printer 1 of this embodiment, a paper feed cassette 3 as a paper feed unit is detachably attached to a lower portion of a main body case 2, and recording sheets stacked in the paper feed cassette 3 by a plurality of paper feed rollers 4 and the like. The paper P as a medium is separated one by one, and between the image forming unit 7 and the transfer unit base 8 having a transfer roller 9 as a transfer member via the paper guide plate 5 and the feeding roller pair 6. Sent.

The image forming unit 7 includes a photosensitive drum 10.
A developing device unit 11 including a toner tank and a developing roller 12, and a charging device 13 including a charging roller,
A cleaning (not shown) device and the like are housed in a case as one kit to form a single unit. A scanner unit 22 including a laser emitting section 23, a lens 24, a reflecting mirror 25, and the like is arranged above the image forming unit 7, and below the transfer unit table 8 the charging device 13 and the transfer roller 9 are arranged. A high voltage substrate 26 for applying a high voltage is arranged, and a control substrate 27 is arranged below the fixing unit 15.

The surface of the photosensitive drum 10 precharged by the charging device 13 is irradiated with light emitted from the scanner unit 22 in accordance with image data transmitted from an external device such as a host computer (not shown). The electrostatic latent image is formed on the surface of the photoconductor drum 10, and then the developing roller 12 is rotated to supply the charged powdery toner to visualize the latent image. After that, the toner image is transferred onto the paper P supplied between the photosensitive drum 10 and the transfer roller 9. Next, the paper P, which is conveyed by sliding on the paper passage guide member 32 on the front surface side (upper side) of the transfer unit base 8 which will be described later, passes between the heating roller 16 and the pressing roller 17 in the fixing unit 15. Then, heat and pressure are applied to the transferred image to fix the toner image on the paper P. After that, the paper is discharged to the paper tray 21 on the upper surface of the main body case 2 via the paper discharge guide plate 18, the intermediate roller pair 19, and the paper discharge roller pair 20.

An embodiment of the transfer device of the present invention will be described below with reference to FIGS. The transfer unit base 8 is formed by injection molding with a synthetic resin having an electrical insulation property such as ABS resin. As shown in FIG. 2, one side of the upper surface of the base plate 8a of the transfer unit base 8 is formed as shown in FIG. ,
Bifurcated for vertically movably supporting the bearings 30 (only one is shown in FIG. 3) at the left and right ends of the conductive (metal) shaft 9a of the transfer roller 9 made of conductive sponge or conductive rubber. A groove-shaped support portion 31 is provided so as to project upward. In addition,
The bearing 30 is configured such that the transfer roller 9 is pressed against the lower circumferential surface of the photoconductor drum 10 by a biasing means 30a such as a metallic (conductive) coil. At least one of the bearings is made of a conductive material (metal or a composite member in which carbon black, graphite, and metal powder are dispersed in a synthetic resin). Then, the one bearing 30 (or the biasing means 30a) having the conductivity is provided.
The lower ends of the terminals (both not shown) of the wiring connected to are pressedly contacted with the flat plate-shaped electrode portion formed on the upper surface of the high-voltage board 26 to electrically connect them.

As shown in FIGS. 2 and 4, on the upper surface of the horizontal plate portion 8b in the downwardly opened support step portion of the base plate 8a adjacent to the support portion 31, as shown in FIGS. A plurality of fin-shaped passage guide members 32 for guiding toward the fixing unit 15 are integrally provided so as to project upward. At the position of the base plate 8a between the support portion 31 and the passage guide member 32, a charge eliminating plate 33 for removing the electrostatic charge charged on the sheet P that has passed through the transfer portion is erected upward and is not shown. Secure with screws. Further, the horizontal plate portion 8b is provided with a flat plate portion 34a of an auxiliary static eliminator plate 34 having a laterally L-shaped cross section, and the vertical plate portion 34b of the auxiliary static eliminator plate 34 is provided on a side remote from the static eliminator plate 33. It is attached to the outer surface of the plate portion 8c and fixed by the fixing means 35 described later.

Next, the connection relationship between the static elimination plate 33 and the auxiliary static elimination plate 34 will be described. As shown in FIG. 4, the static eliminator plate 33 formed of a conductive metal plate such as an iron plate has its upper end formed in a saw shape, and a wide surface of the static eliminator plate 33 has a vertically long trapezoidal shape ( Only one contact portion 36 is shown in FIG.
Make a notch and raise it sideways. On the other hand, as shown in FIGS. 3 and 4, each of the fin-shaped passage guide members 32 has a root portion 37 protruding upward from the horizontal plate portion 8b of the transfer unit base 8 on the side close to the static elimination plate 33. The side away from the static elimination plate 32 (downstream side of conveyance of the paper P)
Then, the length L1 and the vertical gap H between the upper surface of the horizontal plate portion 8b and
One slit 38 is formed.

Further, a projection 39 is provided integrally with the flat plate portion 34a of the auxiliary static eliminator plate 34 shown in FIG. 4 so as to be in electrical contact with each of the contact portions 36. Further, an insertion groove 40 is formed on the tip side of the flat plate portion 34a of the auxiliary static eliminator plate 34 so that the auxiliary guide plate 32 can be inserted while avoiding the root portions 37 of the passage guide members 32. Then, from a pair of elastic locking claws 35a, 35a protruding rearward from the recess 42 of the vertical plate portion 8c, with respect to the locking hole 41 formed in the vertical plate portion 34b of the auxiliary static eliminator plate 34 and having a rectangular shape or the like. That is, the fixing means 35 is fitted and locked.

As a result, as shown by the alternate long and short dash line in FIG. 4, the auxiliary static eliminator plate 34 is moved in the direction of the static eliminator plate 33 so that each insertion groove 40 is located at the rear end side of the fin-shaped passage guide member 32. By pushing, the passage guide member 32
Auxiliary neutralization plate 34 made of metal plate without damaging the upper edge of
Can be disposed above the horizontal plate portion 8b, and the auxiliary static elimination plate 34 and the static elimination plate 33 can be connected to the contact portion 36 and the projection 39.
It can be electrically connected to the edge of. And the fixing means 3
Since the vertical plate portion 34b of the auxiliary static eliminator plate 34 can be locked in a non-retractable manner at position 5, the contact portion 36 and the projection 39 can be simultaneously attached to the auxiliary static eliminator plate 34 on the transfer unit base 8. It is possible to maintain the pressed state at all times reliably, and prevent accidents where electrical contact becomes defective.

Even if the wide surface of the auxiliary static eliminator plate 34 is subjected to an electrically insulating surface treatment such as rust-preventive coating, when the auxiliary static eliminator plate 34 is formed, the protrusion 39 can be formed by pressing. Since the thick portion of the projection 39 can be easily exposed as a metal surface, the metal surface at the edge of the projection 39 is removed from the static elimination plate 33.
The contact portion 36 can be electrically and surely contacted. Further, even in the cut-and-raised contact portion 36, the metal surface can be surely exposed, and the cut-and-raised contact portion 36 itself has an elastic force in contact with the edge of the projection 39 at an acute angle. Since it has, the projection 39 and the contact portion 36 can be surely electrically connected.

Then, as shown in FIG. 3, an electrically insulating property is integrally provided downwardly from a base plate 8a of the transfer unit base 8 located above the high voltage substrate 26 fixed to a support frame (not shown). A conductive (metallic or the like) coil-shaped terminal 42 is arranged in the inner diameter portion of the tubular guide body 41 that is provided, and one end of the terminal 42 is connected to the base portion of the static eliminator plate 33 by wire connection. If the other end is pressed into contact with the grounding electrode 43 on the upper surface of the high voltage substrate 26, the static eliminator 33 and the auxiliary static eliminator 34 can be connected to the ground (potential 0) all at once. It is possible to efficiently remove the electrostatic charge that has been charged on the paper P when passing through the location above the plate 34.

As shown in FIG. 5, the high voltage substrate 26
The transfer unit base 8 is formed in the shape of an open downward box as a supporting means for attaching and supporting the edge portion of the high voltage substrate 26 so that the high voltage substrate 26 is completely covered in the box. Then, of the four side plates 45 integrally projecting downward from the base plate 8a of the transfer unit base 8, at least two facing side plates 45 are used as a support means for supporting the edge portion of the high-voltage board 26. To do.

In this case, the inner surface of the side plate 45 is formed with an engaging claw 46 which can be engaged with and engaged when the high voltage board 26 is pushed into the box portion. According to this embodiment, similarly to the above-described embodiments, the transfer unit base 8 can be mounted at a predetermined position while the high-voltage board 26 is mounted on the back surface side of the transfer unit base 8 in advance so that it cannot be removed. At the same time, since the high-voltage board 26 is completely surrounded by the box on the back side of the transfer unit base 8 having an electric insulation property, even if an operator touches the passage guide member 32 to remove the paper jam, an electric shock will occur. It is safe without.

Further, as shown in FIG. 5, the inner diameter of the electrically insulating cylindrical guide body 41 integrally projecting downward from the base plate 8a of the transfer unit base 8 is electrically conductive (metallic). Etc.) coil-shaped terminals 42 are arranged, and one end of the terminals 42 is connected to the static eliminator plate 33, while the other end (lower end) of the terminals 42 is formed on the upper surface of the high-voltage board 26 for grounding. The electrode portion 43 is pressed and brought into contact therewith. With this configuration, the high voltage substrate 2 is provided on the back surface side of the transfer unit base 8.
At the same time as the work of mounting 6, the static elimination plate 33 and the auxiliary static elimination plate 3
Since the electrical connection work with 4 is completed, there is an effect that the installation work can be extremely simplified.

It goes without saying that the present invention can also be applied to a transfer device in an electrostatic electrophotographic image forming apparatus such as a facsimile or a copying machine.

[0022]

As described above, claim 1
A transfer device in an image forming apparatus according to the invention described above applies a transfer voltage to a transfer member that faces a surface of an image carrier that carries and rotates a toner image, and a toner image is applied to a recording medium such as a sheet that passes through the transfer member. In the image forming apparatus configured to transfer the recording medium, a transfer unit base made of an electrically insulating material, in which a support portion of the transfer member and a passage guide member for the recording medium are erected on the surface, A plate-shaped static elimination needle, which is arranged downstream of the conveyance, is provided between the support portion and the passage guide member along the longitudinal direction of the transfer member so that the passage guide member can be erected. The flat plate portion of the auxiliary static eliminator plate having an L-shaped cross section is placed on the upper surface of the horizontal plate portion, and the vertical plate portion of the auxiliary static neutralizer plate is fixed to the vertical portion of the support step portion, while the flat plate of the auxiliary static neutralizer plate is mounted. Abutting the tip edge of the part to the side surface of the static elimination needle It is those that were.

Therefore, according to the present invention, the transfer unit base is provided with a support portion for supporting the transfer member, a passage guide member for facilitating the passage of the recording medium, and a support means, and the transfer unit. Since the static eliminator plate and the auxiliary static eliminator plate are arranged using the unit base as a common component, the number of necessary parts is small, and the work of attaching the static eliminator plate and the auxiliary static eliminator plate is extremely simple.

Then, after the parts of the transfer member, the static eliminator plate and the auxiliary static eliminator plate are mounted on the transfer unit base in advance, and then the transfer unit base is mounted on a predetermined place, the mounting work of these parts can be collectively performed. As a result, the disassembling work can be performed at one place, the labor of assembling and disassembling work can be greatly simplified, and the manufacturing cost can be significantly reduced.

According to a second aspect of the present invention, in the transfer device of the image forming apparatus according to the first aspect, a side surface of the static elimination needle is electrically connected to a tip of a flat plate portion of the auxiliary static elimination plate. The abutting portion is cut and raised to be molded. Therefore, according to the present invention, in addition to the action and effect of the invention according to claim 1, when the auxiliary static eliminator plate is connected to the static eliminator plate,
At the cut-and-raised abutting portion, the metal surface can be surely exposed, and it comes into contact with the tip of the auxiliary static eliminator at an acute angle, and the cut-and-raised abutting portion itself has an elastic force. The effect that the electrical connection between the auxiliary static eliminator plate and the contact portion can be surely achieved.

Further, the invention according to claim 3 is the transfer device in the image forming apparatus according to claim 1 or 2, wherein the support plate portion of the transfer unit base and a plurality of fin-like passages standing upright therefrom. Between the guide member,
A gap is formed on the downstream side of the conveyance of the recording medium away from the transfer site, and on the tip side of the flat plate portion of the auxiliary charge-eliminating plate,
An insertion groove is formed to avoid the root between the upper surface of the horizontal plate portion and each passage guide member in the support step portion.

According to the present invention, in addition to the function and effect of the invention according to claim 1 or 2, when the auxiliary charge erasing plate is mounted on the transfer unit base, the fin-shaped passage guide member is viewed from the plate thickness direction. Since the insertion groove in the auxiliary static eliminator can be inserted, the edge of the fin-shaped passage guide member is not damaged, and even if there are multiple passage guide members, the auxiliary static eliminator plate can be configured and installed as one sheet. Thus, there is an effect that the assembling and disassembling work becomes easier.

[Brief description of drawings]

FIG. 1 is a schematic side sectional view of a laser printer.

FIG. 2 is a side sectional view of a main part of a transfer device.

FIG. 3 is a side sectional view of the first embodiment.

FIG. 4 is a partially cutaway perspective view of a transfer unit base, a static eliminator and an auxiliary static eliminator.

FIG. 5 is a cross-sectional view of main parts of another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printer 2 Main body case 7 Image forming unit 8 Transfer unit stand 8a Base plate 8b Horizontal flat plate part 8c Vertical plate part 9 Transfer roller 10 Photosensitive drum 11 Developing device unit 26 High voltage board 31 Support part 32 Passage guide member 33 Static elimination plate 34 Auxiliary static elimination plate 34a Flat plate portion 34b Vertical plate portion 35 Fixing means 36 Abutting portion 37 Base portion 38 Slit 39 Protrusion 40 Insertion groove

Claims (3)

[Claims] 1. A transfer member is configured to transfer a toner image onto a recording medium such as a sheet of paper which passes through the transfer member by applying a transfer voltage to a transfer member which faces the surface of an image bearing member which carries and rotates the toner image. In the image forming apparatus, a transfer unit base made of an electrically insulating material, on the surface of which a support portion for the transfer member and a passage guide member for the recording medium are erected, is arranged on the downstream side of the transfer portion for conveying the recording medium. Then, between the support and the passage guide member, a long plate-shaped static elimination needle is erected along the longitudinal direction of the transfer member, and a horizontal support step portion for erected the passage guide member is provided. A flat plate portion of an auxiliary static eliminator plate having an L-shaped cross section is placed on the upper surface of the plate portion, and the vertical plate portion of the auxiliary static eliminator plate is fixed to the vertical portion of the support step portion, while the flat plate portion of the auxiliary static eliminator plate Make sure that the tip edge is in contact with the side surface of the static elimination needle. And a transfer device in an image forming apparatus. 2. The image forming apparatus according to claim 1, wherein an abutting portion for electrically connecting to a tip end of the flat plate portion of the auxiliary neutralizing plate is cut and raised on a side surface of the neutralizing needle. Transfer device. 3. A gap is formed between the support plate portion of the transfer unit base and a plurality of fin-shaped passage guide members standing upright from the support plate portion, on the downstream side of the conveyance of the recording medium away from the transfer portion. An insertion groove is formed on the tip side of the flat plate portion of the auxiliary static eliminator plate so as to avoid the root between the upper surface of the horizontal plate portion of the supporting step portion and each passage guide member. 2. A transfer device in the image forming apparatus according to 2.