JPH07140754A - Electrostatic charger and image forming device - Google Patents

Abstract

PURPOSE:To always stably tense an electrostatic charging wire in an excellent state whenever and whoever tenses the wire by providing a means for setting the length of the wire to be tensed inside an electrostatic charger. CONSTITUTION:Inside a shielding case 1, one end of the electrostatic charging wire 3 is held by a spring 2 attached to a hook 6 and the other end of the wire 3 is fixed at the end part of the shielding case 1, which is connected to a power source. Then, a length setting mark 5 for fixing the length of the wire 3 is put at a proper position on the end part side of the case 1 from a positioning plate 4 for deciding the position of the wire 3. In the case of tensing the wire 3, the end part of the wire 3 unwound from a bobbin is fixed at one end of the case 1, and the wire 3 is extended in a longitudinal direction in the case 1 and hooked on the end of the spring 2 detached from the hook 6 at the position of the mark 5. Then, the spring 2 is twisted, the wire 3 is fixed at the end of the spring 2 and cut, and the other end of the spring 2 is engaged with the hook 6.

Description

Detailed Description of the Invention

[0001]

[Object of the Invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrostatic transfer process, such as an electrostatic copying machine and a printer, and a charger for the same.

[0002]

In the well-known image forming apparatus as described above, charging of the photosensitive layer on the surface of the image carrier,
It is well known that a corona discharger (hereinafter referred to as a charger) is widely used for transferring a toner image on an image carrier to a transfer material, separating the transfer material from the image carrier, and other parts. It is as follows.

In general, this type of charger has a structure in which a charging wire is spread in a shield case having a substantially U-shaped cross section with one surface open. It is necessary to determine the length of the wire so that it can be stretched with an appropriate tension, but there is usually no standard for setting the wire length in the shield case, and the range of the appropriate length of the wire is very limited. The actual situation is that it is performed depending on the experience and experience of a serviceman who replaces the wires.

Therefore, in the case of an inexperienced service person,
It was unavoidable that the wire re-swapping failed, the wire wasted, and the service took too long.

The present invention has been made to cope with such a situation, and a means for determining the length of the extended wire is provided in the shield case of the charger so that the charged wire is always charged no matter who the time is. It is an object of the present invention to provide a charger which can stably spread the toner in a good condition.

[0006]

[Constitution of the invention]

In order to achieve the above object, the present invention is provided with means for setting the length of the charging wire to be extended inside the charging device. Of the charging device or the surface of the image carrier is charged, then a toner image is formed on the electrostatic latent image formed on the charged surface, the toner image is transferred to a transfer material, and the transfer material is separated from the image carrier. In the image forming apparatus including a step of using a corona discharger for at least one of the steps of latent image formation, pre-transfer charging, transfer and separation, the length of the charging wire in the corona discharger is increased. It is characterized in that means for setting the height is provided.

With this configuration, any person can easily and accurately replace the charging wire in a short time without requiring special experience or skill.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS "FIG. 1" is a perspective view of a part of a charger showing an embodiment of the present invention, in which a charging wire 3 is provided inside a shield case 1 having a U-shaped cross section with its upper surface opened. One end of is held by a spring 2 attached to a hook 6.
Reference numeral 4 in the drawing is a positioning plate that determines the position of the charging wire 3. The other end of the wire 3 is fixed to an end of the shield case 1 on the side not shown, and the end is connected to a power source (not shown).

In such a charging device, in the apparatus shown in the figure, a length setting mark 5 for determining the length of the wire is provided at a proper position on the end side of the shield case from the positioning plate 4.

With such a structure, when the charging wire is extended, the end of the wire unwound from the bobbin 7 is shielded by the shield case 1 as shown in FIG.
After being fixed to one end of the wire, the inside of the shield case is extended in the longitudinal direction and hooked at the end of the spring 2 removed from the hook 6 at the position of the length setting mark 5, and then the spring 2 is twisted to twist the wire 3 Is fixed to the end of the spring 6, the wire is cut, and the other end of the spring 2 is engaged with the hook 6.

By such an operation, the charging wire is
The charging wire can be stretched in the shield case with moderate tension for any person without requiring special skill.

FIG. 3 and FIG. 4 are plan views showing the essential parts of another embodiment, and FIG. 5 is a side view of the same portion to which the wire is fixed. As shown in "FIG. 3", a pair of wire sandwiching members 8, 8 are arranged in a portion of the shield case where one end of the charging wire is fixed. The sandwiching members 8 and 8 have fine irregularities formed on the surfaces for sandwiching the wire 3, and cutters 8'and 8'are provided on the end side of the case 1.

The sandwiching members 8 and 8 extend below the shield case as shown in FIG. 5, one of which is fixed to the shield case 1, and a screw 9 is arranged between both members. Both members 8 are brought into contact with and separated from each other by the rotation of the screw 9. Therefore, when the wire 3 in the shield case is positioned between the sandwiching members 8 and 8 and the screws 9 are brought into contact with each other,
The wire 3 is firmly held on the uneven surfaces of the members 8 facing each other.

As described above, each of the sandwiching members 8, 8 is provided with a cutter 8 ', 8'. After the sandwiching member holds the wire, when the screw 9 is further tightened, the cutter is attached to the wire 3. 8'and 8'act and cut this.

With such a structure, it is possible to always attach the charging wire at a predetermined position with a constant tension without requiring special skill. In this case, the sandwiching member 8 is preferably made of a material having some elasticity such as rubber having high hardness.

FIG. 6 is a plan view of a main part of still another embodiment, and FIG. 7 is a side view of the wire holding member. A wire winding member 11 is fixed at a predetermined position closer to the shield case than the positioning plate 4, and a restraining member 10 is disposed in the vicinity of the wire winding member 11 so as to be able to come into contact with and separate from the member 11.

Both the winding member 11 and the restraining member 10 extend below the shield case, and a screw 9 can be used to connect and separate these members.

One end of the charging wire unwound from the bobbin is attached to an end position (not shown) of the shield case, and the wire portion extending inside the case and beyond the positioning plate 4 is wound around the winding member 11 once or once. Set the wire length by winding several times.

Then, the holding member 10 is brought into contact with the winding member 11 by the screw 9 to fix the wire at this position, and then the unnecessary portion is cut. The winding member 11 is preferably made of a material having appropriate elasticity such as rubber having high hardness. With such a configuration, the charging wire can be spread in a constant state without requiring special skill.

[0020]

As described above, according to the present invention,
Since the charging device with the charging wire extended is equipped with a means for setting the length of the charging wire at the proper position of the charging device, it does not require special skill, and it is possible to replace the charging wire with appropriate tension without taking time to perform the work. It will be possible.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of a charging device according to an embodiment of the present invention.

FIG. 2 is a plan view for explaining how to spread the charging wire.

FIG. 3 and

FIG. 4 is a plan view of an essential part showing another embodiment.

FIG. 5 is a side view showing the fixing means for the charging wire.

FIG. 6 is a plan view showing still another embodiment.

FIG. 7 is a side view showing the fixing means of the charging wire of the same.

[Explanation of symbols]

 1 Shield Case 2 Spring 3 Charging Wire 4 Positioning Plate 5 Length Setting Mark 8 Clipping Member 8'Cutter 9 Screw 10 Wire Fixing Member 11 Wire Holding Member

Claims (5)

[Claims] 1. A charger for an image forming apparatus, comprising means for setting a length of a charging wire to be extended inside the charger. 2. The charger according to claim 1, wherein the means for setting the length of the charging wire is a length setting mark provided in the shield case. 3. The charger according to claim 1, wherein the means for setting the length of the charging wire is a pinching member for holding and cutting the charging wire provided in the shield case. 4. The charging wire length setting means comprises a winding member for winding the charging wire, which is provided in the shield case, and a restraining member for fixing the charging wire to and away from the winding member. The charging device described above. 5. A toner image is formed on an electrostatic latent image formed on the charged surface after charging the surface of the image carrier, the toner image is transferred to a transfer material, and the transfer material is separated from the image carrier. An image forming apparatus including a step, wherein the corona discharger is used in at least one of latent image formation, pre-transfer charging, transfer, and separation steps. An image forming apparatus, characterized in that a means for setting is set.