JPH085478Y2 - Corona discharger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a corona discharger used in an image forming apparatus such as a copying machine.

[Conventional technology]

For example, in an electrophotographic copying machine, a main charging corona discharger for charging the photosensitive drum, a transfer corona discharger for transferring the toner image on the photosensitive drum onto the paper, and the paper from the photosensitive drum are used. Various corona dischargers, such as a paper separation corona discharger for separating paper, are used.

This corona discharger generally has a shield case with a U-shaped cross section having a discharge opening, and a corona discharge wire (hereinafter, referred to as a charge wire) stretched over the longitudinal direction of the shield case. ing. In addition, a shield frame body having insulating blocks fixed to both ends is slidably fitted in a shield case, and a charge wire is stretched between the insulating blocks to form the shield frame body, the insulating block, and the charge wire. There is also provided a corona discharger that can be pulled out from the shield case as a unit.

In the corona discharger used in the copying machine as described above, the developer from the developing device may be scattered and adhere to the wall surface of the insulating block. When the developer adheres to the wall surface of the insulating block, discharge is generated along the wall surface between the charge wire to which a high voltage is applied and the shield case. Particularly when the humidity is high, creeping discharge is likely to occur, and, for example, transfer may not be successful, or a warning may be issued to notify an abnormality of the device.

Therefore, for example, as shown in Japanese Utility Model Publication No. 62-26759, near the wire positioning guide portion of the insulating block,
In some cases, a partition wall having a window or a notch portion through which the charge wire is inserted in a non-contact state is provided, and a gap is formed between the partition wall and the wire positioning guide portion. In such a corona discharger, the creeping distance between the charge wire and the shield case becomes long, and creeping discharge hardly occurs.

[Problems to be solved by the device]

By the way, in the corona discharger, both ends of the charge wire are fixed to the insulating block by locking means such as screws. And on the upper surface of this insulating block,
A lid is provided to prevent the developer, dust, and the like from entering, but creeping discharge may occur between the screw and the like for fixing the charge wire and the shield case via the lid.

Especially in large-sized copying machines and high-speed copying machines,
It is necessary to apply a high voltage to the transfer corona discharger, and a creeping discharge is likely to occur in the shield case from the screw fixing the charge wire as described above, passing through the lid of the insulating block.

Further, there is also one in which two charge wires are provided in the shield case and the voltage applied to each charge wire is lowered so that creeping discharge is less likely to occur. However, if two charge wires are provided, space is required for that,
Further, the work of setting the wire tension becomes troublesome, and the voltage application control becomes complicated.

An object of the present invention is to provide a corona discharger in which a creeping discharge does not occur from a locking portion of a charge wire to a shield case even when a high voltage is applied to the charge wire.

[Means for solving the problem]

In the corona discharger according to the present invention, insulating blocks having locking portions for holding the ends of the corona discharge wire and lids for covering the locking portions are provided at both ends of the shield case, and between the insulating blocks. A corona discharge wire is stretched.

This corona discharger includes a wire locking member and an insulating member. The wire locking member locks the end of the corona discharge wire to the locking portion and connects the corona discharge wire to the external lead-out terminal. The insulating member is made of an elastic material, has a notch for positioning corresponding to the shapes of the locking portion and the lid portion of the insulating block, and covers the wire locking member and the lid portion and the wire locking member. It is positioned by using the notch between and.

[Action]

In the present invention, the insulating member is provided in the insulating block portion so as to cover the wire locking member. Therefore, the creeping distance from the wire locking member to the shield case becomes long, and creeping discharge is unlikely to occur even when a high voltage is applied to the charge wire. Further, since the insulating member is made of a material having elasticity and is positioned by using the notch, it can be easily arranged along the space in the insulating block, and the positioning is easy.

〔Example〕

FIG. 6 shows a copying machine using a corona discharger according to an embodiment of the present invention. In FIG. 6, an original table 12 is provided on the upper surface of the copying machine main body 11, and an original conveying means 13 is provided on the upper part thereof. And the copier body
The document placed on the right side of the upper part of the drawing 11 is conveyed to the left side of the drawing by each of the conveyance rollers provided in the document table 12 and the document conveying means 13.

Inside the copying machine main body 11, an exposure device 14 for reading a document is provided above the main body. The exposure device 14 is composed of a light source, a Selfoc lens, and the like. A photoconductor drum 15 on which an electrostatic latent image is formed is arranged in the center of the copying machine main body 11. Around the photoconductor drum 15, a main charging corona discharger 16 that charges the photoconductor drum 15 to a predetermined charge, a developing device 17 that develops an electrostatic latent image, and a transfer device that transfers a toner image on paper. A corona discharger 18, a sheet separation corona discharger 19 for separating a sheet from the photosensitive drum 15, and a cleaning device 20 for removing residual toner on the photosensitive drum 15 are arranged.

A paper feed cassette 8 is detachably attached to the lower part of the copying machine main body 11. And this paper feed cassette 8
A sheet feeding path 21 is provided between the image forming section formed by the photosensitive drum 15 and the like. Further, a paper discharge path 22 is provided on the downstream side of the image forming unit, and a fixing device 30 for fixing the toner image on the conveyed paper is arranged further downstream of the paper discharge path 22. .

Next, details of the corona discharger will be described in detail with reference to FIGS. 1 to 5B. In this embodiment, the transfer corona discharger 18 and the paper separating corona discharger 19 are unitized and integrally configured. FIG. 1 is an exploded view of the unitized corona dischargers 18 and 19 (hereinafter, these unitized corona dischargers are simply referred to as corona dischargers). Double corona discharger 1 as shown
The reference numerals 8 and 19 are symmetrical about the partition wall 9.

Each corona discharger has a metal shield case 25
And a shield frame 26 slidably fitted in the shield case 25, box-shaped insulating blocks 27 and 28 made of resin, and a charge stretched between the insulating blocks 27 and 28. And a wire 29. The insulating block 27,2
8 is fixed to both upper surfaces of both ends of the shield frame body 26 with screws or the like, and the shield frame body 26, the insulating blocks 27 and 28, and the charge wire 29 are integrally drawn out from the shield case 25 as shown in FIG. , Or can be inserted.

The insulating block 27, as shown in FIGS. 1 and 4A,
A boss 30 is provided near the outer wall 27a. A protrusion 31 is formed on the upper surface of the boss 30, and a spring 32 for setting the tension of the charge wire 29 is locked to the protrusion 31. Then, one end of the charge wire 29 is fixed to the spring 32. Further, on the inner wall 27b side, a V for supporting the charge wire 29 on the upper surface via a predetermined gap with the inner wall 27b.
A wire support portion 33 having a groove is formed. Further, as shown in FIG. 1, a cleaning member 34 formed of an acrylic pile seal material or the like is attached to the end of the side wall 27c of the insulating block 27. The cleaning member 34 is arranged so as to come into sliding contact with the inner surface of the shield case 25 when the shield frame 26 slides in the shield case 25.

The insulating block 28, as shown in FIGS. 1 and 5A,
It has a boss 35 in its approximately central portion. A female screw is formed at the center of the boss 35, and the other end of the charge wire 29 is fixed to the boss 35 by a washer 36 and a screw 37. In addition, the insulating block 28
In the vicinity of the inner wall 28b of the, with a predetermined gap with the inner wall 28b,
A wire support portion 38 having a V groove formed on the upper surface is formed.

Further, as shown in FIG. 3, a terminal 46 for applying a high voltage to the charge wire 29 is provided below the insulating block 28.
Is provided. The terminal 46 is electrically connected to the charge wire 29 via a screw 37.

Above the locking portions of the charge wires 29 of the insulating blocks 27 and 28, that is, above the spring 32 and the screw 37,
Insulating films 40 and 41 are arranged so as to cover them. The shape of these insulating films 40, 41 when mounted is
Fig. 4B and Fig. 5B show the respective states when they are deployed.

The insulating film 40 disposed on the insulating block 27 side is
As shown in Figure 4B, it is formed in a substantially rectangular shape and has a notch.
It has 40a and 40b. Notch 40a is isolated block 2
The protrusions 31 of FIG. 7 and the spring pressing protrusions on the lower surface of the lid, which will be described later, are to escape, and the notch 40b is formed in the insulating block 27
Screw boss 27d (4th
(See Figure A).

Further, the insulating film 41 arranged on the insulating block 28 side.
Also, as shown in FIG. 5B, it is formed in a substantially rectangular shape and has notches 41b and 41c and a notch 41a. Cutout 4
1c is for escaping the connecting portion 28e formed between the side wall 28c of the insulating block 28 and the boss 35, and the notch 41b.
Is for escaping the screw boss 28d (see FIG. 5A) for attaching the insulating block 28 to the shield frame 26. The notch 41a is for escaping a protrusion formed on the lower surface of the lid, which will be described later.

As shown in FIG. 1, lids 42 and 43 are detachably attached to the upper surfaces of the insulating blocks 27 and 28, respectively. Locking portions 42a and 43a projecting downward are formed on the side portions of the lids 42 and 43, and the locking portions 42a and 43a are formed on the side walls of the insulating blocks 27 and 28, respectively. It can be locked to the claws 27f and 28f. A protrusion 42b is formed on the lower surface of the lid 42. The lower end of the protrusion 42b passes through the notch 40a of the insulating film 40, and the protrusion 3 in the insulating block 27
One end of the spring 32 locked to 1 is pushed down. The lid 43 on the insulating block 28 side does not need the protrusion 42b as described above, but the protrusion 43b is also provided in order to share the both lids 42 and 43.

The shield case 25 has a discharge opening at the top, is formed in a U-shaped cross section, and is attachable to the frame side plate of the copying machine main body 11. The upper end of the side wall is bent in the paper transport direction. A protrusion 25c is formed by cutting and raising a part of the one bent portion 25a, and a notch 25d is formed in the other bent portion 25b. And
As shown in FIG. 2, a nylon wire 45 is hung on the upper surface of the shield case 25 by utilizing the projections 25c and the cutouts 25d.

It should be noted that the nylon wire 45 is stretched outwardly along the paper transport direction (from the upper side to the lower side in FIG. 2) with the central portion of the shield case 25 in the longitudinal direction as a boundary. . As a result, even if the curled paper is conveyed, the end of the paper is spread outward along the nylon wire 45 and does not enter the shield case 25.

 Next, the function and effect will be described.

The operation of the copying machine main body 11 is exactly the same as the conventional one.
The original is placed on the original table 12 by the rollers such as the original conveying means 13.
The document is conveyed above and the information of this document is optically read by the exposure device 14. The image information of the document is recorded on the photosensitive drum 15 as an electrostatic latent image and developed by the developing device 17. On the other hand, from the paper feed cassette 8 or the like to the paper feed path 21
The sheet is conveyed through the sheet, and the toner image is transferred onto the sheet by the transfer corona discharger 18. The sheet on which the toner image has been transferred is separated from the photoconductor drum 15 by the sheet separation corona discharger 19, and the sheet discharge path 22 and the fixing device 30.
Then, the sheet is discharged to a sheet discharge tray (not shown).

In such a copying operation, especially in a large device,
A high voltage is applied to the charge wires 29 of the transfer corona discharger 18 and the paper separation corona discharger 19. Therefore,
Through the insulating blocks 27, 28 and the lids 42, 43, a creeping discharge is likely to occur between the shield wire 25 and the charge wire 29, the means for locking the charge wire 29, that is, the screw 37 and the spring 32. In particular, the top of the spring 32 or screw 37 and the lid 4
Since the gap is narrow between 2, 43, creeping discharge is more likely to occur. However, in this embodiment, since the insulating films 40 and 41 are respectively provided between them, the insulating films 40 and 41 increase the creepage distance between the spring 32 or the screw 37 and the shield case 25. As described above, even if a high voltage is applied to the charge wire 29, creeping discharge is unlikely to occur.

Further, the insulating films 40, 41 of the present embodiment have notches 40b, 41b, respectively, so that the notches 40b, 41b engage with the screw bosses 27d, 28d of the insulating blocks 27, 28, respectively. Therefore, the positioning can be easily performed by utilizing these engagements, and the assembling workability is improved.

In addition, in the corona discharger of this embodiment, the insulating block 27
Since the cleaning member 34 is attached to the
When the shield frame 26 is pulled out from the shield case 25, the cleaning member 34 removes foreign matter such as dust adhering to the inner surface of the shield case 25. Therefore, it is not necessary to wipe the inner surface of the shield case with a waste cloth.

[Other Examples]

(A) In the above embodiment, the case where the number of the charge wires 29 is one has been described. However, in order to reduce the voltage applied to the charge wires, two coronas formed by stretching two charge wires in one shield case. The present invention can be similarly applied to a discharger.

(B) In the above embodiments, the present invention is applied to the transfer corona discharger and the paper separation corona discharger, but it is needless to say that the present invention can be similarly applied to the main charging corona discharger and the like.

(C) In the above embodiment, a spring is used as the wire locking means.
Although the description has been made using 32 and screws 37 as an example, the present invention is applied to creeping wires if they are for locking wires and if creeping discharge is generated between the case and the shield case through the insulating block. Discharge can be prevented.

(D) In the above embodiment, the case where the present invention is applied to the corona discharger of the copying machine has been described, but it goes without saying that the present invention can be applied to the corona discharger of other image forming apparatuses.

[Effect of device]

Thus, according to the present invention, the insulating member is provided so as to cover the locking means of the charge wire, and the creepage distance between the wire locking member and the shield case in the insulating block portion is lengthened. In a high speed copying machine or the like, creeping discharge can be prevented even when a high voltage needs to be applied to the charge wire.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a corona discharger according to an embodiment of the present invention, FIG. 2 is a plan view of the corona discharger, FIG. 3 is a partial perspective view thereof, and FIG. 4A is a view of the corona discharger. Partial view of the insulating block on one end side, FIG. 4B is a developed view of the insulating film disposed in the insulating block, FIG. 5A is a partial view of the insulating block on the other end of the corona discharger, and FIG. FIG. 6 is a development view of the insulating film disposed in the insulating block, and FIG. 6 is a general configuration diagram of a copying machine to which the corona discharger according to the embodiment of the present invention is applied. 25 …… Shield case, 26 …… Shield frame, 27, 28…
… Insulation block, 29 …… Charge wire, 32 …… Charge wire tension setting spring, 37 …… Screw, 40,41 …… Insulating film, 42,43 …… Lid.

Claims (1)

[Scope of utility model registration request] 1. An insulating block having a locking portion for holding an end portion of a corona discharge wire and a lid portion for covering the locking portion is provided at both ends of a shield case, and the corona discharge wire is provided between the insulating blocks. A corona discharger in which a wire is stretched, and a wire locking member that locks an end portion of the corona discharge wire to the locking portion, and connects the corona discharge wire to an external lead terminal, The lid portion and the wire locking member are made of an elastic material and have positioning notches corresponding to the shapes of the locking portion and the lid portion of the insulating block, and cover the wire locking member. A corona discharger comprising: an insulating member that is positioned between and by using the notch.