JPH05908Y2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to a means for eliminating static electricity from a recording material conveyed on a recording material conveyance path in an electrophotographic apparatus, and in particular to a means for removing static electricity from a recording material conveyed on a recording material conveyance path in an electrophotographic apparatus, and in particular, it The present invention relates to an improvement in an electrophotographic apparatus having a control unit for generating and transmitting control signals to electrical components.

"Prior Art" Conventionally, a feeding mechanism, a registration means, a transfer means,
A conveyance guide and a fixing means are arranged, and after guiding the recording material fed from the feeding mechanism onto the transfer position circumference of the image carrier at appropriate timing, transfer is performed by electric discharge, pressure contact, etc. applied from the back side of the recording material. The toner image carried on the image carrier is transferred to the recording material side by a means, and the recording material carrying the transferred unfixed toner image is further transferred by a fixing device located on the downstream side via a conveyance guide. Electrophotographic devices that fix images and are used as copiers, printers, facsimile machines, or combinations of these devices are well known, and in sheet-like recording materials that are transported along such conveyance paths, for example, a feeding roller and a When the recording material is inserted between the friction plate for recording material separation which is pressed onto the circumferential surface of the recording material, an electrostatic charge is charged on the recording material due to the friction between both members, and discharge during transfer. , a residual voltage is charged on the recording material, and when toner powder, which is also electrostatically charged, adheres to the charged recording material, the recording material is fixed due to the electrical repulsion between the two. Disturbances in the unfixed toner image, such as toner scattering, trailing, and front-drawing, occur before the toner reaches the container, and after the image is fixed, the toner image has bleeding, blurred edges, etc., and a clear image cannot be formed. .

Furthermore, if the recording material with residual charge is ejected onto the ejected toner, electrical repulsion will occur between the accumulated recording materials, and the recording material will not be densely deposited, resulting in a decrease in the storage amount of the recording material. In some cases, the recording material may become uneven, and furthermore, the residual charge may give an unpleasant electrical shock to the operator.

In order to eliminate this drawback, a static elimination brush is placed in the middle of the conveyance guide that is formed while the recording material reaches the fixing device after the toner image is transferred, or the conveyance guide itself is made of a grounded metal material. The structure is such that the charging of the recording material is removed by forming the recording material.

``Problems to be solved by the invention'' However, in a configuration that uses a static elimination brush, there is a risk that the unfixed toner image carried on the recording material may be disturbed due to minute vibrations caused by the friction between the static elimination brush and the recording material. Not only that, but arranging the static eliminating brush in a narrow area is not only subject to layout constraints, but also increases the number of parts, leading to an increase in cost.

Furthermore, if the conveyance guide itself is made of a grounded metal material, the metal material must be fixed to the lower frame made of resin using screws or other means, which also complicates the assembly work. At the same time, the cost increases, and a ground wire for connecting the metal material to the external ground terminal must be routed inside the device, and accidents such as breakage of the ground wire are likely to occur.

In view of the shortcomings of the prior art, the present invention effectively utilizes a cover member that surrounds a control board for generating and sending control signals to the optical scanning unit and other electrical components, thereby alleviating the above-mentioned shortcomings of the prior art. The purpose of the present invention is to provide an electrophotographic device that solves the problems described above.

"Means for Solving Problems" In laser printers and other types of equipment that utilize electrophotographic technology, various devices built into the equipment, such as generating and sending out modulated signals to be sent to the optical scanning unit, are used. Generate control signals for control
A control board is built in for sending out the data, and the control board handles various high-pressure discharges during the electrophotographic process on the main body of the device, magnetic fields generated during development, or static electricity charged on the recording material, toner, etc. mentioned above. In order to prevent malfunctions caused by various noises such as electrical charges, it is necessary to electromagnetically hide or block the control board, and for this reason, the unit is generally hidden with a grounded conductive cover member. It is customary to have

Therefore, the present invention makes effective use of a cover member that hides such a control board, and preferably the cover member is placed at any location on the recording material conveyance path from the transfer position to the fixing position. The gist of the present invention is that a part of the recording material is raised toward the recording material conveying path side, and the raised portion is configured to be able to face the recording material.

In this case, the raised portion of the cover member may function as a conveyance guide, but if configured in this way, large holes will be formed in the frame body that holds various members located on the recording material conveyance path with the conveyance guide as a boundary. , the strength of the frame body may be weakened. Therefore, in a preferred embodiment, a resin frame body interposed between the recording material transport path and the conductive cover member forms a recording material transport guide from the transfer position to the fixing position, and at least It is preferable that a portion be opened so that the conductive cover member and the recording material can face each other through the opening.

"Effect" According to this technical means, the grounded cover member that hides the control board functions as a static eliminator, so there is no need for a special static eliminator brush or static eliminator, and it can be connected to an external ground terminal. There is no need for a ground wire, etc., resulting in a reduction in the number of parts, the elimination of layout constraints for arranging static eliminating brushes, etc., achieving lighter weight and smaller size, and because the ground wire does not need to be routed around the device. In addition, various accidents such as breakage of the ground wire can be prevented.

Furthermore, by raising the cover member to function as a static eliminator, the dead space that previously existed below the conveyance guide is eliminated, and the equipment space can be used effectively. The effective space of the control board has been expanded, and the control board can be configured in two stages using the expanded effective space.As a result, the control unit itself consisting of the control board and cover member can be Miniaturization can be achieved.

Further, by configuring the raised portion of the cover member to be tightly accommodated in the recessed portion of the frame body formed below the conveyance guide, the raised portion can function as a control unit positioning guide.

Embodiments Hereinafter, preferred embodiments of the present invention will be described in detail by way of example with reference to the drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described in this example are as follows, unless otherwise specified.
This is not intended to limit the scope of this invention, but is merely an illustrative example.

FIG. 1 shows the configuration of main parts of a laser printer according to an embodiment of the present invention. To roughly explain the configuration, 1 is a device main body side A on which various parts for an electrophotographic process are assembled; Control unit 2
The lower frame body 1 is made of insulating resin and separates the recording material from the storage space B which stores the recording materials. a registration roller 3 that guides the photoreceptor to the transfer position, a guide 4, a transfer device 6 disposed facing the lower peripheral surface of the photoreceptor drum 5,
A conveyance roller 7 that guides the recording material led out from the transfer device 6 to a conveyance guide 10 formed on the upper surface side of the lower frame body 1, a fixing roller pair 8 that thermally fixes the unfixed toner image, and the like are provided. Device side wall surface 30 rising vertically from the end of the lower frame body 1
At the top, a paper ejection guide 31 and a paper ejection roller 32 are disposed for inverting and ejecting the recording material on which the image has been fixed by the pair of fixing rollers 8. Reference numeral 9 in the figure represents a drum unit detachably fixed to the upper frame (not shown).

On the other hand, the control unit 2 housed in the space B below the lower frame body 1 includes a control board (not shown), a lower unit 21a surrounding and fixing the control board, and a conductive cover member 21 for electromagnetically shielding the control board. It becomes more.

Next, the structure of the lower frame body 1 and the cover member 21, which is the gist of the present invention, will be explained in detail.

The lower frame body 1 has a gentle arc-shaped recess on the upper surface side of the lower frame body 1 extending from the top of the exit end side of the storage recess 11 of the transport roller 7 to the entrance end of the fixing roller pair 8, and excludes both ends thereof. An opening 12 is formed in the center in the shape of a generally wide band over the entire conveyance width of the recording material.
A large number of arc-shaped conveyance ribs 13 are bridge-formed in parallel to the conveyance direction between 10b to function as a recording material conveyance guide 10.

On the other hand, the cover member 21
0 is formed in the lower surface side concave space 14 of the lower frame body 1 is raised in the same shape as the concave space 14, and the upper surface 22a of the raised portion 22 is raised along the opening 12 part of the lower frame body. 1. An external ground terminal 24 is attached to the side wall surface 23 of the cover member that stands upright along the side wall of the device.
Connect.

According to this embodiment, the external ground terminal 2
Since the raised part upper surface 22a of the cover member 21 electrically connected to the cover member 4 faces the recording material conveyance path through the opening 12 of the conveyance guide 10, By guiding the recording material charged with static charge due to discharge onto the transport guide 10 via the transport roller 7, the charge is removed by facing the raised portion 22 of the cover member 21 located on the lower surface side, and the recording material is recorded. Disturbance of the unfixed toner image supported on the material can be prevented.

Further, since the raised portion 22 is formed in the same shape as the concave space 14 on the lower surface side of the lower frame body 1, the concave space 1
4 and the raised portion 22 make it possible to accurately position the control unit 20.

"Effects of the invention" As described above, according to the invention, the cover member of the control box provided below the recording material transport path from the transfer position to the fixing position is effectively used to function as a static elimination plate. , there is no need to provide a special static elimination brush etc. on the conveyance path, increasing the degree of freedom in the equipment layout, reducing the number of parts, downsizing the equipment, and eliminating the complexity of assembly.
It has various effects such as being able to prevent various accidents caused by the routing of the ground wire connected to the static elimination brush etc. within the device.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of essential parts of a laser printer according to an embodiment of the present invention. FIG. 2 is a perspective view showing the shape of the cover member. 21...Cover member, 22...Protuberance, 10...
... Recording material conveyance guide, 1 ... Frame bodies 1, 12
...Opening.

Claims (1)

[Claims for Utility Model Registration] 1) A groundable conductive cover that electromagnetically shields a control board for generating and transmitting control signals for controlling various devices incorporated in an electrophotographic device. The cover member is configured to be able to face the recording material passing on the conveyance path at any point on the recording material conveyance path from the transfer position to the fixing position. Electrophotographic equipment. 2) The electrophotographic apparatus according to claim 1, wherein a part of the cover member is raised toward the recording material conveyance path so that the raised portion can face the recording material. 3) A resin frame body interposed between the recording material transport path and the conductive cover member forms a recording material transport guide from the transfer position to the fixing position, and at least a portion of the transport guide is opened. The electrophotographic apparatus according to claim 1, which is a registered utility model, and is configured such that the conductive cover member and the recording material can face each other through the opening.