JPH11119513A - Electrifier for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve improvement of an electrifying wire in terms of assemblage and to stabilize the tension of the electrifying wire at a low cost by fixing both ends of the electrifying wire to one insulation block, engaging the turned- back part of the electrifying wire, almost the middle of it, by means of an elastic member, and fixing the elastic member to the other insulation block. SOLUTION: The electrifying wire 40 is a wire made of a single piece of tungsten material or the like, and both its ends 403 and 404 form rings and are locked in the position of a locking part 302. Also, the turned-back part of nearly the middle of the electrifying wire 40, situated on a middle line 11, is attached to a locking part 211 via an extension spring 50 being the elastic member, and tension is thus applied to the electrifying wire 40. Because the engagement part of the extension spring 50 for the electrifying wire 40 is engaged with the middle of the electrifying wire 40 with almost no frictional resistance, more uniform tension is steadily applied to the discharging parts 401 and 402 of the electrifying wire 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charger for an image forming apparatus (also referred to as a charger), and more particularly, to a discharging charger used in an image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, for example, a charger shown in FIG. 2 has been known as a discharge charger used in an image forming apparatus. FIG. 2 is a front view (a) and side view A of a conventional charger.
It is A sectional drawing (b). In the figure, metal shield case 1
Insulating blocks 60 and 62 are attached to both ends of
A charging wire 6 for discharging between the insulating blocks 60 and 62
4 is installed. End 6 of one charging wire 64
44 is attached to the locking portion 611 of the conductive member 61 fixed to the insulating block 60, passes through the groove 601, passes through the groove 621 of the insulating block 62, and is folded back at the center at the locking portion 622, so that the groove 621 of the insulating block 60 is Street, locking part 611
Is attached via a tension spring 67.
A conductive member 61 for applying a voltage to the charging wire 64 is fixed to the insulating block 60. Note that 64
1, 642 is a discharge unit.

FIG. 3 shows a front view (a) and a side view AA cross section (b) of another conventional charger. In the figure, insulating blocks 70 and 72 are attached to both ends of a metal case 10, and a charging wire 74 for discharging is attached between the insulating blocks 70 and 72. One charging wire 7
The four ends 743 and 744 of the fourth member pass through the groove 701 and are fixed by balls 751 and 752, and the balls 751 and 752 are fixed to the wire holder 71 made of an insulating material. The charging wire 74 is fixed to the insulating block 70 via a tension spring 76, and the folded portion at the center of the charging wire 74 is connected to the lead rod 7 of the other insulating block 72.
3 is fixed. Note that 741, 742
Denotes a discharge unit (Japanese Patent Application Laid-Open No. 48-94443).

[0004]

In the former charger shown in FIG. 2, however, tension is applied to the discharge portion 641 side of the charging wire 64 stretched between the insulating blocks by the tension spring 67. On the side 642, the tension of the tension spring is given via the discharge part 641, the groove 621 and the locking part 622. Therefore, the tension on the discharge unit 642 side is smaller than that on the discharge unit 641 side, and therefore, the discharge unit 642 side cannot maintain the accuracy of the interval between the charging wire (not shown) and the photoconductor, and the uniformity of the discharge is poor. Further, the latter charger of FIG. 3 requires the wire holder 71 of the charging wire, and thus has a problem that the cost is increased and the assembly is complicated.

SUMMARY OF THE INVENTION The object of the present invention has been made in view of the above-mentioned problems, and has an assembling property of a charging wire, a low cost,
An object of the present invention is to provide a charger for an image forming apparatus in which the tension of a charging wire is stable.

[0006]

The above object is achieved by the following means. That is, a charger for an image forming apparatus including a metal shield case, insulating blocks attached to both ends of the shield case, and a discharge charging wire whose periphery is covered by the shield case between the insulating blocks. In the above, both ends of the charging wire is fixed to one of the insulating blocks, a substantially central folded portion of the charging wire is engaged by an elastic member,
A charging device for an image forming apparatus, wherein the elastic member is fixed to the other insulating block.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. FIG. 1 is a front view (a) and a side view AA cross-sectional view (b) of the charger of the embodiment.

In the figure, a shield case 10 is a metal case surrounding the periphery of a charging wire 40, and insulating blocks 20 and 30 are attached to both ends of the case 10. The insulating block 30 has a locking portion 302 for locking both ends of the charging wire 40, and has two grooves 301 for positioning the charging wire 40 in parallel with the center line 11. Also,
The insulating block 20 has a locking portion 211 for locking the central folded portion of the charging wire 40 via the tension spring 50, and has two grooves 201 for positioning the charging wire 40 parallel to the center line 11. Note that the locking portion 211 is fixed to the insulating block 20 and the charging wire 4 is
It is provided on a conductive member 21 for applying a voltage to zero.
Note that the locking portions 302 and 211 are provided on the center line 11.

The charging wire 40 is a single wire made of tungsten or the like, and has both ends 403 and 404 in a ring shape. Further, a folded portion on the center line 11 substantially at the center of the charging wire 40 is attached to the locking portion 211 via a tension spring 50 as an elastic member, so that tension is applied to the charging wire 40. Discharge portions 401 and 4 of charging wire 40
Numeral 02 is charged on, for example, the surface of the photoreceptor indicated by a two-dot chain line 12 in FIG. Since the engaging portion of the charging wire of the tension spring 50 engages the central portion of the charging wire 40 with almost no frictional resistance, it applies a stable and even tension to the discharging portions 401 and 402 of the charging wire. I have.

In the embodiment, both ends 403 and 404 of the wire are locked to the locking portion 302.
The wire may be provided at each position and both ends of the wire may be locked. Further, although a tension spring is used as the elastic member, the present invention is not limited to this, and a leaf spring or the like may be used.

[0011]

As described above, according to the present invention, the charging device has good assemblability of the charging wire, is low in cost, and has a stable tension of the charging wire.

[Brief description of the drawings]

FIG. 1 is a front view and a side sectional view of a charger of an embodiment.

FIG. 2 is a front view and a side sectional view of a conventional charger.

FIG. 3 is a front view and a side sectional view of another conventional charger.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Shield case (case) 20 Insulating block 21 Conductive member 211 Locking part 30 Insulating block 302 Locking part 40 Charging wire 50 Tension spring

Claims (1)

[Claims] 1. A metal shield case, and insulating blocks attached to both ends of the shield case, respectively.
In an image forming apparatus charger having a discharge charging wire whose periphery is covered by the shield case between the insulating blocks, both ends of the charging wire are fixed to one of the insulating blocks, and A charging device for an image forming apparatus, wherein a substantially central folded portion is engaged with an elastic member, and the elastic member is fixed to the other insulating block.