JP2978593B2 - Charging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device which is used in an image forming apparatus such as an electrophotographic copying machine or a printer and applies a high voltage to a corona discharge electrode to charge a photosensitive member or a transfer drum. In particular, the present invention relates to a charging device having a device for cleaning a corona discharge electrode made of a wire.

[0002]

2. Description of the Related Art Conventionally, as a device for charging a photoreceptor or a transfer drum of an image forming apparatus, a wire is stretched in parallel with a surface of a drum or the like, and a corona discharge is performed by applying a high voltage thereto. Causing a charge on the surface of a drum or the like. In such a device, a shield case is provided so as to surround the corona discharge electrode in order to prevent an electric field generated by application of a high voltage from spreading to the periphery. A strong electric field is generated between the electrode and the shield case. Along with this, on the inner surface of the corona discharge electrode and shield case,
Charged particles such as toner may adhere. If a large amount of such particles adhere, the charging characteristics deteriorate, and an apparatus for removing these particles is required.

As a charging device having a wire cleaning device as a corona discharge electrode, for example, Japanese Utility Model Application Laid-Open No. 60-90466.
No., Japanese Utility Model Application Laid-Open No. 61-19253, Japanese Utility Model Application Laid-Open No. 62-
There is one described in US Pat.

The charging device disclosed in Japanese Utility Model Laid-Open Publication No. 60-90466 has a pair of holding arms (cleaning members) projecting from a member that moves in a direction parallel to a wire serving as a corona discharge electrode. The vicinity of the tip of the arm is urged to hold the wire via a cloth or the like. The wire is cleaned by moving the holding arm in the axial direction of the wire while holding the wire, and when not performing the cleaning, the holding arm is moved to the resident position provided at the end. In this resident position, a fixed block-shaped opening / closing member is inserted between a pair of holding arms to open and close the wire.

The charging device disclosed in Japanese Utility Model Laid-Open Publication No. 61-19253 has a cleaning member that holds a wire near the tip of a pair of elastic members and moves in the axial direction of the wire. When is located at the end, a protruding pin protruding and fixed in the axial direction of the wire is inserted between the pair of elastic members so as to separate the cleaning member from the wire at one end and re-clamp the cleaning member.

The charging device disclosed in Japanese Utility Model Laid-Open Publication No. Sho 63-43367 has a cleaning member which is movable in the axial direction with a wire interposed therebetween. The member is fixedly provided, and when the cleaning member moves to this portion, the expanding member comes into contact with the distal end portion of the cleaning member and expands.

[0007] Each of the above charging devices has a cleaning device that moves in the axial direction while holding the wire, but it is necessary to separate the cleaning member from the wire when cleaning is not performed or when cleaning is completed. As this method, each of the above-mentioned conventional examples uses a force for moving the cleaning device in the axial direction, and includes a fixing member that pushes and spreads the cleaning member against the force for pinching the wire when it comes to a predetermined position. I have.

[0008]

However, such a charging device has the following problems. Since the power for moving the cleaning device is used to push the cleaning member elastically holding the wire apart from the wire, the load on the power is increased when the cleaning member is separated from the wire. . For this reason, the difference from the load at the time of cleaning becomes large, and a power source capable of large output is required. Accordingly, the power source becomes large, and it is difficult to reduce the size of the entire apparatus.
In addition, in order to perform uniform and stable cleaning, the cleaning member
It must be provided so that the degree of freedom of position with respect to the member to be cleaned (wire and / or shield) is increased to some extent. For this reason, the fixing member that pushes and expands the cleaning member is restricted by the mutual positional accuracy and the state of the cleaning member at the time of opening or cleaning. Further, since the toner and the like adhere to the inside of the shield case, cleaning the inside of the shield case is also an effective means for maintaining the discharge characteristics of the charging device for a long time, and the conventional charging device cleans the shield case. It is necessary to separately provide a member for this.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to clean a wire and stabilize a cleaning member from the wire without imposing a large load on the power for driving the cleaning device. Separation can be performed,
An object of the present invention is to provide a charging device including a cleaning device capable of cleaning the inner surface of a shield case.

[0010]

In order to solve the above-mentioned problems, the present invention provides a corona discharge electrode having a wire stretched thereon, a shield case surrounding the corona discharge electrode and having a discharge opening, and the corona discharge electrode. A charging device including a cleaning device that is movable in an axial direction of an electrode, wherein the cleaning device moves in the axial direction of the corona discharge electrode, and a pair of cleaning members that sandwich the corona discharge electrode. A rubbing portion that rubs against the inner surface of the shield case, and a unidirectional frictional force acting between the rubbing portion and the inner surface of the shield case causes the corona discharge electrode of the cleaning member to rub. It is assumed that the cleaning member and the rubbing portion are provided so as to provide a holding force.

In the above-mentioned charging device, the pair of cleaning members are provided rotatably, and the rubbing portion is composed of two portions that are respectively integrated with the pair of cleaning members, and is formed by frictional force. The pair of cleaning members may be rubbed so as to apply rotational forces in directions opposite to each other.

Further, in the charging device described above, one end of the corona discharge electrode is supported via a spring, and the cleaning device moves from the end of the corona discharge electrode supported via a spring toward an opposite side. When the cleaning member and the rubbing part are arranged such that the frictional force acting on the rubbing part becomes an acting force in a direction separating the cleaning member from the corona discharge electrode. It is desirable that

The cleaning member may directly hold a wire serving as a corona discharge electrode, but it is preferable to hold the cleaning member via a cleaning pad made of nonwoven fabric, foamed urethane, or the like. The rubbing portion has a cleaning pad made of a nonwoven fabric, foamed urethane, or the like, and the cleaning pad can be rubbed against the inner surface of the shield case so that the inner surface of the shield case can be cleaned. Further, the rubbing portion is provided on a member which can be relatively displaced from a member driven in the axial direction of the wire, and it is intended that the frictional force acting on the rubbing portion causes relative displacement between the two members. It is desirable to provide the cleaning member and the rubbing part so that the restricting force at this time is converted into a force for clamping the wire of the cleaning member.

[0014]

In the charging device having the above structure, when the cleaning device is driven in the axial direction of the corona discharge electrode, the sliding portion is rubbed against the inner surface of the shield case. A frictional force acts between them, and the force is transmitted so as to be a force for clamping the corona discharge electrodes of the pair of cleaning members. Accordingly, the cleaning member holds the corona discharge electrode, and in this state, the cleaning device moves in the axial direction of the corona discharge electrode to perform cleaning. By providing a cleaning pad or the like in the rubbing portion, the inner surface of the shield case is also cleaned at the same time. When such a movement of the cleaning device is performed as a reciprocating motion between one end and the other end of the corona discharge electrode, the frictional force acting on the rubbing portion acts in the opposite direction between the forward path and the backward path, and the forward path or the backward path. When the cleaning is performed by holding the corona discharge electrode in one of the above, the frictional force acts on the other to separate the cleaning member from the corona discharge electrode. Therefore, when the corona discharge electrode is cleaned on the outward path, the cleaning member opens the corona discharge electrode on the return path, and when stopped at the end of the electrode, the cleaning member is separated from the corona charged electrode, and a high voltage is applied. It is in a state where it can be applied.

In the charging device according to the second aspect, the rubbing portion and the cleaning member are integrated with each other, and each is a pair.
When the cleaning device is driven, the cleaning devices rotate in opposite directions, so that a pair of cleaning members sandwich the corona discharge electrode on the outward movement of the cleaning device and perform cleaning, and on the return path, the cleaning member performs corona discharge. Even when it moves away from the electrode and stops, it does not come into contact with the corona discharge electrode, and becomes in a state where discharge by applying a high voltage is possible.

In the charging device according to the third aspect, when the cleaning device moves from the end supported by the spring of the corona discharge electrode to the opposite side, the cleaning device is opened without sandwiching the corona discharge electrode. Therefore, without applying excessive tension to the spring supporting the corona discharge electrode, the wire that is the corona discharge electrode is slackened in the traveling direction of the cleaning device, and the installation position of the corona discharge electrode is shifted, The lock does not come off.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1A and 1B are diagrams showing a configuration of a charging device according to one embodiment of the present invention. FIG. 1A is a schematic plan view, and FIG. 1B is a schematic side view. FIG. 2 is a schematic perspective view showing the cleaning device of the charging device of the embodiment. In this charging device, a front block 9 and an end block 10 are connected via a shield case 2 so as to keep a constant interval, and a corona discharge electrode 3 to which a high voltage is applied extends between these blocks. Have been. One end of the corona discharge electrode 3 is attached via a spring 13, and a constant tension is introduced by the spring. The shield case 2 is provided so as to surround three directions around the axis of the corona discharge electrode 3, and prevents the electric field from spreading to the periphery.
A cleaning device 1 is provided inside the shield case 2 so as to be movable in the axial direction of the corona discharge electrode 3. In FIG. 1, reference numeral 15 denotes a guide member for preventing paper or the like from being caught in the charging device and breaking the wire.

The support member 9 of the cleaning device 1 passes through a slit provided in the shield case 2 so that the shield case 2
Is connected to a driver screw 8 located outside of the vehicle.
The driver shaft 7 penetrates through the through hole 8a of the driver screw 8, and the helical projection of the driver shaft 7 and the helical projection provided on the inner surface of the through hole of the driver screw 8 engage. Is driven by the drive unit 14, the driver screw 8 moves in the axial direction.

Two cleaning member bases 6, 6 are rotatably mounted on the support member 9 of the cleaning device 1 by rotating shafts 12, 12. These cleaning member bases 6, 6
The cleaning members 4 and 4 are provided so as to protrude therefrom, and the cleaning members sandwich the corona discharge electrode 3 via the cleaning pads 4a and 4a. A nonwoven fabric is stuck to the side surfaces of the cleaning member bases 6 and 6 and is in contact with the inner surface of the shield case 2 to form the rubbing portions 5 and 5 rubbed when the cleaning device moves. .

Further, projections 6a, 6a, 6b, 6b are provided near the upper and lower portions of the cleaning member bases 6, 6, respectively, and the cleaning members 4, 4 rotate in the direction opposite to the direction in which the corona discharge electrode 3 is clamped. When this occurs, the shield case 2 comes into contact with the inner surface to restrict rotation. The protrusions 6b provided on the lower portion are engaged with the L-shaped protrusions 9a provided on the cleaning member base 6, so that the cleaning member bases 6, 6 can be prevented from coming off from the rotating shafts 12, 12. It has become.

In such a charging device, when cleaning is not performed, the cleaning device 1 is parked at a position close to the end block 10. When cleaning is performed, the driver shaft 7 is rotationally driven by the drive unit 14, and the driver screw 8 moves toward the end on the opposite side of the corona discharge electrode 3. At this time, as shown in FIG. 3A, the moving direction of the cleaning device 1 is in the direction of arrow A, and the rubbing portions 5, 5 on the side surfaces of the cleaning member bases 6, 6 are rubbed against the inner surface of the shield case 2. As shown by arrows C and D in the figure, the two cleaning member bases 6 and 6 try to rotate in opposite directions due to frictional force. The two cleaning members 4, 4 pinch the corona discharge electrode 3 by this rotational force and move in the axial direction of the corona discharge electrode 3 in this state, so that the corona discharge electrode 3 is cleaned. Also shield case 2
Is also rubbed by the rubbing parts 5 and 5 to which the nonwoven fabric is adhered, and is cleaned.

When the cleaning device 1 reaches the opposite end of the corona discharge electrode 3, the drive unit 14 rotates the driver shaft 7 in the reverse direction, and the cleaning device 1 moves in the reverse direction. At this time, as shown in FIG. 3B, the moving direction of the cleaning device 1 is the direction of the arrow B, and the two cleaning member bases 6, 6
Tries to rotate in the directions of arrows E and F. As a result, the cleaning members 4, 4 are separated from the corona discharge electrode 3, return to their original positions while maintaining this state, and stop. Therefore, when a high voltage is applied to the corona discharge electrode 3 to charge the photoconductor and the like, the cleaning members 4 and 4 are in a state of being separated from the corona discharge electrode 3.

Further, since the corona discharge electrode 3 is cleaned only when the cleaning device 1 moves in one direction, the toner or the like peeled off from the wire which is the corona discharge electrode 3 has one end. Only to be paid off, and the function of collecting it can be concentrated in one place. In particular, when the charging device is used to charge the OPC photoconductor, the OPC photoconductor has a wide ineffective area (non-image area) at one end, and is separated from the corona discharge electrode 3. The functions are efficiently concentrated by dropping and collecting the toner and the like on this portion.

Further, the cleaning device 1 uses the spring 13
When moving in the opposite direction from the supporting side via the support, the corona discharge electrode 3 cannot be sandwiched and is separated, so that excessive tension does not act on the spring. There is no loosening, no dislocation of the installation position, and no disengagement of the support.

FIG. 4 is a schematic diagram showing a cleaning device provided in a charging device according to another embodiment of the present invention. In the apparatus shown in FIG. 4, the support member 109 driven by the driving means is provided.
And a pair of cleaning members 104, 104
2, the supporting member 1
09 on the frame body 106 which is relatively movable with respect to
105 is provided. The frame 106 and the pair of cleaning members 104, 104 are connected to rods 115, 115, respectively.
Are connected by

When the support member 109 is driven in the direction of arrow G as shown in FIG. 4 (a), the rod 11 is driven by the frictional force between the sliding portions 105, 105 and the shield case 102.
A compressive force acts on the cleaning members 104, 5 and 115.
Reference numeral 4 sandwiches the corona discharge electrode 103. On the other hand, FIG.
When the support member 109 is driven in the direction of the arrow H as shown in FIG. 7, a tensile force acts on the rods 115, 115, and the cleaning members 104, 104 are separated from the corona discharge electrode 103 and contact the stoppers 116, 116. Touch Thus, the embodiment shown in FIG. 4 has the same function as the embodiment shown in FIG.

[0027]

As described above, in the charging device of the present invention, the corona discharge electrode is pinched by the frictional force generated between the inner surface of the shield case and the rubbing portion when the charging device moves in the axial direction of the corona discharge electrode. Since the cleaning device is provided for cleaning the inner surface of the shield case, the inner surface of the shield case can be cleaned, and a large force is not required to keep the cleaning member separated from the corona discharge electrode during non-cleaning. Therefore, the drive unit of the cleaning device needs only to have a small output, and thus the size of the entire device can be reduced.

A mechanism for cleaning the corona discharge electrode only in one of the reciprocating motions of the cleaning device and separating the corona discharge electrode when moving in the other direction, and for processing the toner separated from the corona discharge electrode by cleaning. Can be centralized. In addition, the tension that is applied by cleaning to the wire that becomes the corona discharge electrode acts only in one direction, and even if the wire is stretched in a simple mechanism, the tension of the wire may shift or the locking portion may fall off. Does not occur.

[Brief description of the drawings]

FIG. 1 is a schematic plan view and a schematic side view showing a configuration of a charging device according to an embodiment of the present invention.

FIG. 2 is a perspective view of a cleaning device provided in the charging device of the embodiment.

FIG. 3 is an explanatory diagram showing an operation of a cleaning device provided in the charging device of the embodiment.

FIG. 4 is an explanatory diagram showing the configuration and operation of a cleaning device provided in a charging device according to another embodiment of the present invention.

[Description of sign]

 DESCRIPTION OF SYMBOLS 1 Cleaning device 2 Shield case 3 Corona discharge electrode 4 Cleaning member 5 Sliding part 6 Cleaning member base 7 Driver shaft 8 Driver screw 9 Front block 10 End block 12 Rotating shaft 13 Spring 14 Drive unit

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03G 15/02 H01T 19/00

Claims (3)

(57) [Claims] 1. A charging device comprising: a corona discharge electrode having a wire stretched thereon; a shield case surrounding the corona discharge electrode and having a discharge opening; and a cleaning device movable in an axial direction of the corona discharge electrode. In the apparatus, the cleaning device includes a pair of cleaning members that sandwich the corona discharge electrode,
A rubbing portion that rubs against the inner surface of the shield case when the cleaning device moves in the axial direction of the corona discharge electrode; and one that acts between the rubbing portion and the inner surface of the shield case. The charging device according to claim 1, wherein the cleaning member and the rubbing portion are provided such that a frictional force in the direction becomes a force for clamping the corona discharge electrode of the cleaning member. 2. The charging device according to claim 1, wherein the pair of cleaning members are provided rotatably, and the rubbing portion is formed of two portions each integrated with the pair of cleaning members. And a pair of cleaning members that are rubbed by frictional force so that rotational forces in opposite directions are applied to the pair of cleaning members. 3. The charging device according to claim 1, wherein one end of the corona discharge electrode is supported via a spring, and the cleaning device is supported via a spring of the corona discharge electrode. When moving from the end to the opposite side, the frictional force acting on the rubbing portion is such that the frictional force acting on the cleaning member and the sliding member is such that the frictional force acts in a direction away from the corona discharge electrode. A charging device, wherein a rubbing part is arranged.