JPH04337761A - Electrostatic charging device - Google Patents

Abstract

PURPOSE:To obtain an electrostatic charging device which is used in an image forming device such as an electrophotographic copying machine or a printer, which electrostatically charges a photosensitive body and a transfer drum, by impressing high voltage on a corona discharge electrode, where the corona discharge electrode is cleaned and a cleaning member is separated from the electrode without imposing a large load on a driving source which drives a cleaning device for the corona discharge electrode and which is provided with the cleaning device which cleans the inside surface of a shield case. CONSTITUTION:A cleaning device 1 which moves in the axial direction of the corona discharge electrode 3 is provided with a sliding and rubbing part 5 which slides and rubs the inside surface of the shield case 2, and the part 5 and the cleaning member 11 are provided so that frictional force in one direction which acts on the part 5 becomes force for interposing the corona discharge electrode 3 by the cleaning member 4. When the moving direction of the device 1 becomes reverse, the frictional force which acts on the part 5 also acts in a reverse direction, so that the member 4 is separated from the electrode 3.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a charging device used in image forming apparatuses such as electrophotographic copying machines and printers, which charges a photoreceptor, transfer drum, etc. by applying a high voltage to a corona discharge electrode. In particular, the present invention relates to a charging device having a device for cleaning a corona discharge electrode made of a wire.

0002

[Prior Art] Conventionally, as a device for charging a photoreceptor, a transfer drum, etc. of an image forming apparatus, a wire is stretched parallel to the surface of the drum, etc., and a high voltage is applied to the wire to discharge corona discharge. There are known devices that generate electric charges and apply charges to the surface of a drum or the like. In such devices, a shield case is provided to surround the corona discharge electrode in order to prevent the electric field generated by the application of high voltage from spreading to the surrounding area. A strong electric field is created between the electrode and the shielding case. Along with this, the corona discharge electrode and the inside of the shield case,
Charged particles such as toner may adhere. If a large number of such particles adhere, the charging characteristics will deteriorate, so a device for removing them is required.

[0003] As a charging device having a cleaning device for a wire which is a corona discharge electrode, for example, Japanese Utility Model Application No. 60-90466
Publication No. 19253, Utility Model Application No. 61-19253, Publication No. 19253-
There is one described in 43367 publication.

[0004] The charging device disclosed in Japanese Utility Model Application Publication No. 60-90466 has a pair of clamping arms (cleaning members) protruding from a member that moves in a direction parallel to a wire that is a corona discharge electrode. The vicinity of the tip of the arm is biased to sandwich the wire through cloth or the like. The clamping arms move in the axial direction of the wire while clamping the wire to clean the wire, and when cleaning is not performed, the clamping arms are moved to a permanent position provided at the end. In this permanent position, a fixed block-shaped opening/closing member is inserted between the pair of clamping arms to release the wire.

The charging device disclosed in Japanese Utility Model Application Publication No. 61-19253 has a cleaning member that sandwiches a wire near the tips of a pair of elastic members and moves in the axial direction of the wire. When the cleaning member reaches the end, a protruding pin that is fixed and protrudes in the axial direction of the wire is inserted between a pair of elastic members to separate one end of the cleaning member from the wire and clamp it again.

The charging device disclosed in Japanese Utility Model Application Publication No. 62-43367 has a cleaning member which is movable in the axial direction while holding a wire therein, and a wedge-shaped expansion is formed at the movement limit position of the cleaning member. The member is fixedly provided, and when the cleaning member moves to this area, the expanding member abuts the tip of the cleaning member and expands.

[0007] All of the above-mentioned charging devices have a cleaning device that clamps the wire and moves in the axial direction, but it is necessary to separate the cleaning member from the wire when cleaning is not performed or when cleaning is completed. As for this method, all of the above conventional examples utilize a force that moves the cleaning device in the axial direction, and are equipped with a fixing member that pushes and spreads the cleaning member against the force that clamps the wire when it reaches a predetermined position. There is.

[0008]

However, such a charging device has the following problems. Since the power to move the cleaning device is used to push apart the cleaning member that elastically holds the wire and separate it from the wire, the load on the power increases when the cleaning member is separated from the wire. . For this reason, the difference in load during cleaning becomes large, and a power source capable of high output is required. As a result, the power source becomes large, making it difficult to downsize the entire device. In addition, in order to perform uniform and stable cleaning, cleaning materials must be
Parts to be cleaned (wire and/or shield)
It is necessary to provide a certain degree of freedom in positioning. For this reason, the fixing members that push and spread the cleaning members are subject to restrictions on their relative positional accuracy and ensuring the condition of the cleaning members when opening or cleaning. Furthermore, since toner and the like adhere to the inside of the shield case, cleaning the inside of the shield case is an effective means to maintain the discharge characteristics of the charging device for a long time. It is necessary to separately provide a member for this purpose.

The present invention was made in view of the above-mentioned problems, and its purpose is to clean the wire and stabilize the cleaning member from the wire without imposing a large load on the power for driving the cleaning device. It is possible to perform a certain separation,
To provide a charging device equipped with a cleaning device capable of cleaning the inner surface of a shield case.

0010

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a corona discharge electrode formed by stretching a wire,
In the charging device, the charging device includes a shield case surrounding the corona discharge electrode and having a discharge opening, and a cleaning device movable in the axial direction of the corona discharge electrode, wherein the cleaning device includes a pair of cleaning devices that sandwich the corona discharge electrode. A cleaning member;
a sliding 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 a portion that acts between the sliding portion and the inner surface of the shield case. The cleaning member and the rubbing portion are provided so that the frictional force in the direction serves as a force for sandwiching the corona discharge electrode of the cleaning member.

[0011] Further, in the above-mentioned charging device, the pair of cleaning members are each rotatably provided, and the sliding portion is composed of two parts that are each integral with the pair of cleaning members, and is charged by frictional force. The pair of cleaning members may be rubbed so as to apply rotational forces in mutually opposite directions.

Furthermore, in the above charging device, one end of the corona discharge electrode is supported via a spring,
When the cleaning device moves toward the opposite side from the end supported by the spring of the corona discharge electrode, the frictional force acting on the sliding portion separates the cleaning member from the corona discharge electrode. It is desirable that the cleaning member and the rubbing portion be arranged so that the acting force is in the direction of the cleaning member.

Although the cleaning member may directly sandwich the wire serving as the corona discharge electrode, it is preferable to sandwich the wire through a cleaning pad made of nonwoven fabric, urethane foam, or the like. The rubbing portion may include a cleaning pad made of nonwoven fabric, urethane foam, or the like, and this cleaning pad can be rubbed against the inner surface of the shield case to clean the inner surface of the shield case. The sliding portion is provided on a member that can be displaced relative to the member driven in the axial direction of the wire, to prevent relative displacement of both members due to the frictional force acting on the sliding portion. It is desirable to provide a cleaning member and a sliding portion so that the wire is restrained and the restraining force at this time is converted into a force for clamping the wire of the cleaning member.

[0014]

[Operation] In the charging device configured as described above, when the cleaning device is driven in the axial direction of the corona discharge electrode, the sliding portion is rubbed on the inner surface of the shield case, so that the contact between this sliding portion and the shield case is Frictional force acts between them, and this force is transmitted to sandwich the corona discharge electrodes of the pair of cleaning members. Therefore, the cleaning members sandwich the corona discharge electrode, and in this state, the cleaning device moves in the axial direction of the corona discharge electrode to perform cleaning. Furthermore, by providing a cleaning pad or the like in the sliding portion, the inner surface of the shield case can be cleaned at the same time. When such 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 sliding portion acts in opposite directions on the outward and return trips, and When cleaning is performed by holding the corona discharge electrode in one of the two, frictional force acts on the other to separate the cleaning member and the corona discharge electrode. Therefore, when the corona discharge electrode is cleaned on the outward journey, the cleaning member leaves the corona discharge electrode open on the return journey, and when the cleaning member stops at the end of the electrode, the cleaning member is separated from the corona charging electrode and applies a high voltage. The state is now ready for application.

[0015] In the charging device according to the second aspect, the rubbing portion and the cleaning member are integrated, and each constitutes a pair.
When the cleaning device is driven, it rotates in opposite directions, so the pair of cleaning members sandwich the corona discharge electrode during the forward movement of the cleaning device, and the pair of cleaning members clean the corona discharge electrode during the return movement. Even when it moves away from the electrode and stops, it does not come into contact with the corona discharge electrode, making it possible to apply high voltage and discharge.

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 toward the opposite side, the corona discharge electrode is not held between the cleaning devices and the cleaning device is in an open state. This prevents excessive tension from being applied to the spring that supports the corona discharge electrode, and prevents the corona discharge electrode from becoming misaligned due to loosening of the wire that is the corona discharge electrode in the direction of movement of the cleaning device. This prevents the lock from coming off.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of a charging device according to an embodiment of the present invention, in which FIG. 1A is a schematic plan view and FIG. 1B is a schematic side view. Further, FIG. 2 is a schematic perspective view showing the cleaning device for the charging device of the above embodiment. In this charging device, a front block 9 and an end block 10 are connected to each other through a shield case 2 so as to maintain a constant interval, and a corona discharge electrode 3 to which a high voltage is applied is connected between these blocks.
is stretched out. One end of this corona discharge electrode 3 is attached via a spring 13, and a certain tension is introduced by this spring. The shield case 2 is provided so as to surround the corona discharge electrode 3 on three sides around its axis, and prevents the electric field from spreading to the periphery. A cleaning device 1 movable in the axial direction of the corona discharge electrode 3 is provided inside the shield case 2 . In FIG. 1, reference numeral 15 is a guide member that prevents paper or the like from being caught in the charging device and breaking the wire.

The supporting member 9 of the cleaning device 1 is inserted into the shield case 2 through a slit provided in the shield case 2.
The driver screw 8 is connected to the outside of the holder. The driver shaft 7 passes through the through hole 8a of the driver screw 8, and the spiral protrusion of the driver shaft 7 and the spiral protrusion provided on the inner surface of the through hole of the driver screw 8 engage with each other. When the driver screw 8 is rotationally driven by the drive unit 14, the driver screw 8 moves in the axial direction.

Two cleaning member bases 6, 6 are rotatably attached to the support member 9 of the cleaning device 1 via rotation shafts 12, 12. These cleaning member bases 6, 6
Cleaning members 4, 4 are provided so as to protrude from these, and these cleaning members sandwich the corona discharge electrode 3 via cleaning pads 4a, 4a. In addition, a nonwoven fabric is attached to the side surfaces of the cleaning member bases 6, 6, and is in contact with the inner surface of the shield case 2, forming rubbing parts 5, 5 that are rubbed when the cleaning device moves. .

Furthermore, protrusions 6a, 6a, 6b, and 6b are provided near the upper and lower parts of the cleaning member bases 6, 6, respectively, so that the cleaning members 4, 4 rotate in a direction opposite to the direction in which the corona discharge electrode 3 is held. When the shield case 2 is rotated, it comes into contact with the inner surface of the shield case 2 and restricts rotation. Further, the protrusions 6b, 6b provided at the bottom engage with the L-shaped protrusions 9a, 9a provided on the cleaning member base 6, and have a structure that can prevent the cleaning member bases 6, 6 from coming off the rotating shafts 12, 12. It becomes.

In such a charging device, the cleaning device 1 is parked at a position close to the end block 10 when cleaning is not performed. When cleaning is performed, the driver shaft 7 is rotationally driven by the drive unit 14, and the driver screw 8 moves toward the opposite end of the corona discharge electrode 3. At this time, as shown in FIG. 3(a), the moving direction of the cleaning device 1 is the direction of arrow A, and the sliding parts 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, 6 tend to rotate in opposite directions due to frictional force. Due to this rotational force, the two cleaning members 4, 4 sandwich the corona discharge electrode 3 and move in the axial direction of the corona discharge electrode 3 in this state, so that the corona discharge electrode 3 is cleaned. Further, the inner surface of the shield case 2 is also rubbed by the rubbing parts 5, 5 to which a nonwoven fabric is attached, and cleaning is performed.

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 opposite direction and the cleaning device 1 moves in the opposite direction. At this time, as shown in FIG. 3(b), the cleaning device 1 moves in the direction of arrow B, and the two cleaning member bases 6, 6 try to rotate in the directions of arrows E, F. As a result, the cleaning members 4, 4 become 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 photoreceptor, etc., the cleaning members 4, 4 are in a state separated from the corona discharge electrode 3.

Furthermore, since the cleaning device 1 cleans the corona discharge electrode 3 only when moving in one direction, the toner etc. peeled off from the wire that is the corona discharge electrode 3 will be removed from one end. This means that the function to collect this can be concentrated in one place. Particularly when the charging device is used to charge an OPC photoreceptor, the OPC photoreceptor has a large ineffective area (non-image area) at one end, and the OPC photoreceptor may be peeled off from the corona discharge electrode 3. Functions are efficiently integrated by dropping toner and the like into this area and collecting it.

Furthermore, the cleaning device 1 connects the wire to the spring 13.
When the wire is moved in the opposite direction from the side supported by the corona discharge electrode 3, the corona discharge electrode 3 is not pinched but separated, so that no excessive tension is applied to the spring, and the wire is moved on the opposite side of the corona discharge electrode 3. No loosening, shifting of the installation position, or disengagement of the support part will occur.

FIG. 4 is a schematic diagram showing a cleaning device included in a charging device according to another embodiment of the present invention. In the device shown in FIG. 4, the support member 109 is driven by the drive means.
A pair of cleaning members 104, 104 are attached to rotating shafts 112, 11.
2, and this support member 1
A sliding part 105 is provided on the frame body 106 which is movable relative to the sliding part 105.
105 is provided. This frame 106 and the pair of cleaning members 104, 104 are connected to rods 115, 115, respectively.
are connected with.

When the support member 109 is driven in the direction of arrow G as shown in FIG.
Compressive force acts on the cleaning members 104, 10
4 sandwich the corona discharge electrode 103. On the other hand, Figure 4(b)
When the support member 109 is driven in the direction of the arrow H as shown in FIG. come into contact with In this way, the embodiment shown in FIG. 4 also has the same functions as the embodiment shown in FIG.

[0027]

[Effects of the Invention] As explained above, in the charging device of the present invention, the corona discharge electrode is clamped by the frictional force generated between the inner surface of the shield case and the sliding portion when the corona discharge electrode moves in the axial direction. Since a cleaning device for cleaning this is provided, it is possible to also clean the inner surface of the shield case, and a large force is not required to keep the cleaning member separated from the corona discharge electrode when not being cleaned. Therefore, it is sufficient to use a drive unit with a small output for the cleaning device, thereby making it possible to downsize the entire device.

In addition, the cleaning device can clean the corona discharge electrode only in one direction of the reciprocating movement, and can be separated when moving in the other direction, and has a mechanism for processing toner peeled off from the corona discharge electrode by cleaning. can be centralized. Furthermore, the tension applied to the wire that serves as the corona discharge electrode due to cleaning acts only in one direction, and even if the wire tensioning method is simple, the tensioning position may shift or the locking part may fall off. Does not occur.

[Brief explanation of drawings]

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

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

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

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

[Explanation of sign]

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

Claims (3)

[Claims] 1. A charging device comprising a corona discharge electrode formed by stretching a wire, a shield case surrounding the corona discharge electrode and having a discharge opening, and a cleaning device movable in the 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, and a sliding 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. the cleaning member and the sliding portion so that a unidirectional frictional force acting between the sliding portion and the inner surface of the shield case serves as a force for sandwiching the corona discharge electrode of the cleaning member. A charging device characterized by being provided with. 2. In the charging device according to claim 1, each of the pair of cleaning members is rotatably provided, and the sliding portion is formed of two parts each integral with the pair of cleaning members. A charging device characterized in that the pair of cleaning members are rubbed so as to apply rotational forces in opposite directions to each other by frictional force. 3. The charging device according to claim 1 or 2, wherein one end of the corona discharge electrode is supported via a spring, and the cleaning device is supported via the spring of the corona discharge electrode. When moving from the end toward the opposite side, the frictional force acting on the sliding portion is a force acting in the direction of separating the cleaning member from the corona discharge electrode. A charging device characterized in that a rubbing part is arranged.