JP3269697B2 - Discharge 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 discharge device used for an image forming apparatus such as a copying machine, a facsimile, a printer, etc. or various devices having a charging means and the like. The present invention relates to a discharge device including a discharger having a shield case, a discharge electrode stretched in the shield case, and a means for applying a voltage to the discharge electrode.

[0002]

2. Description of the Related Art Conventionally, as a discharge device of this type, for example, as shown in FIGS. 2A and 2B, a position facing a photosensitive drum 4 to be discharged is used. A shield case 1 is provided as a back electrode member having a grid electrode 3 in an opening of a corona wire 2 serving as a main discharge electrode member.
And a corotron charger having no grid electrode 3 are known. FIG. 2 (a)
2 has a shape in which three sides of the corona wire 2 are surrounded by the shield case 1 except for the opening on the photosensitive drum 4 side. In the charger shown in FIG. Although an opening is also provided on the opposite side of the facing position, the opening extends to a position immediately above the corona wire 2. By using the shield case 1 having such a shape, the discharge current flowing through the shield case 1 grounded to the ground can be increased, the discharge can be stabilized, and an image without unevenness can be obtained.

[0003] In a discharge device utilizing corona discharge, discharge-generating substances such as ozone and nitrogen oxides are generated with the discharge. If this ozone stays in the shield case 1 and the concentration increases, or if nitrogen oxides adhere to the inside of the shield case 1, the corona wire 2, the grid electrode 3, etc., stable discharge cannot be obtained. Or unevenness in density or white spots on the image.

Therefore, as shown in FIGS. 3 (a) and 3 (b), a discharge device is used to remove and clean a discharge-producing substance attached to the inside of the shield case 1, the corona wire 2, the grid electrode 3, and the like. At least one of the inside of the shield case 1, the corona wire 2, the grid electrode 3, and the like is cleaned by rubbing with a cleaning pad 6b fixed to a pad holding portion 6a of the cleaning member 6. Here, in order to move the cleaning member 6 along the direction in which the corona wire 2 is stretched, a screw hole is formed in the slider portion 6c of the cleaning member 6, and the feed screw 5 is inserted so as to engage with the screw hole. The feed screw 5 is appropriately rotated and driven by a cleaning member driving means (not shown) such as a motor. This feed screw 5
Is provided outside the shield case 1 so as not to be affected by the discharge current.

Further, in the above-mentioned conventional discharge device, measures are taken so that the discharge-producing substance does not stay in the vicinity of the corona wire 2, especially in the shield case 1. For example, a slit 1c for an air flow path is provided in the shield case 1 above the corona wire 2 to exhaust ozone and nitrogen oxides, and an exhaust device that prevents ozone and nitrogen oxides from staying in the shield case 1 is provided. Can be provided. Here, in order to efficiently discharge ozone, nitrogen oxides, and the like in the shield case 1, it is necessary to provide an opening as large as possible on the surface of the shield case 1 other than the opening on the photosensitive drum 4 side.

[0006]

However, in the above-mentioned conventional discharge device, as shown in FIG. 3A, the feed screw 5 needs to be provided outside the shield case 1, so that the height of the discharge device is high. There is a problem that the dimension in the vertical direction becomes large, and the machine body provided with this discharge device also becomes large.

Further, in the above-described conventional discharge device, it is necessary to provide an opening as large as possible on a surface other than the opening on the photosensitive drum 4 side of the shield case 1, so that the area of the shield case 1 is reduced. The performance as a back electrode is reduced, and the margin of stable discharge is reduced. In order to allow a larger discharge current to flow when the shield case 1 having such a small area is used, the shield case 1 may be brought closer to the corona wire 2, but in this case, the margin for the electric leakage is provided. And the fluctuation of the current when the shield case 1 is contaminated becomes large.

The present invention has been made in view of the above problems, and a first object of the present invention is to provide a discharge device capable of improving exhaust performance without significantly impairing discharge stability. It is a second object of the present invention to provide a discharge device capable of reducing the size of the cleaning mechanism and the size of the discharge device without significantly deteriorating the discharge stability.

[0009]

In order to achieve the first object, the invention according to claim 1 comprises a shield case having at least an opening directed to an object to be discharged and a discharge case stretched in the shield case. a discharger and an electrode, in the discharge device provided with a voltage application means to the discharge electrode, an opening is formed in a portion of the shield case, the opening one
In part, extend in stretched direction of the discharge electrodes, One or and is characterized in that a metal bar which is grounded directly or via the voltage generator.

In order to achieve the second object,
According to a second aspect of the present invention, there is provided a discharger having at least a shield case having an opening directed toward an object to be discharged and a discharge electrode stretched in the shield case, and at least a part of members constituting the discharger. A cleaning member for cleaning, a guide member for guiding the cleaning member in a direction in which the discharge electrode extends, a driving unit for moving the cleaning member along the guide portion, and A discharge device provided with the power supply device, wherein an opening is formed in a part of the shield case, and the guide member having at least a surface formed of a conductive material is disposed in the opening, and the guide member is provided. Are grounded directly or via voltage generating means.

[0011] The invention of claim 3 is the invention according to claim 1 or 2.
In the above discharge device, cleaning means for cleaning the surface of the conductive member or the guide member is provided.

[0012]

According to the first aspect of the present invention, the conductive member having at least a surface formed of a conductive material extends in a direction in which the discharge electrode extends in an opening formed in a part of the shield case. And is grounded directly or via voltage generating means. As a result, the discharge current also flows through the conductive member, so that the opening area of the opening of the shield case can be increased while maintaining a stable discharge, and the pressure loss of the airflow when exhausting from the opening is made. Is to be reduced.

According to the second aspect of the present invention, the guide member, at least a surface of which is formed of a conductive material, extends in a direction in which the discharge electrode extends in an opening formed in a part of the shield case, In addition, they are grounded directly or via voltage generating means. As a result, a discharge current also flows through the guide member, thereby reducing the height of the discharger while maintaining stable discharge.

According to the third aspect of the present invention, the surface of the conductive member or the guide member is cleaned by the cleaning means. This is to prevent insulation.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a charger used in an electrophotographic copying machine (hereinafter referred to as a copying machine) as an image forming apparatus will be described. FIG. 1A is a front view showing a schematic configuration of the scorotron charger according to the present embodiment, and FIG. 1B is a plan view seen from the direction of arrow B in FIG. 1A. This charger is a scorotron charger for uniformly charging the photoconductor layer on the surface of the photoconductor drum 4 to be discharged, and includes a shield case 1 and two discharge electrodes stretched in the shield case 1. And a grid electrode 3 and the like.

The shield case 1 extends in the longitudinal direction of the cylindrical photosensitive drum 4 and is formed of a metal plate member so as to surround the corona wire 2. Openings 1a, 1
b is formed. A grid electrode 3 is provided in the opening 1a at a position facing the photosensitive drum 4.
Although the shield case 1 is grounded to the ground, a predetermined voltage may be applied to stabilize the discharge, or a voltage stabilizing element such as a Zener diode for maintaining the predetermined voltage may be connected. .

The corona wire 2 is connected to the shield case 1
Are stretched by applying a predetermined tension by an elastic member (not shown) between end blocks (not shown) provided at both ends in the longitudinal direction. Further, a high voltage is applied to the corona wire 2 by a high voltage power supply for corona wire as a voltage applying means (not shown), and the charging potential on the photosensitive drum 4 is applied to the grid electrode 3 from a power supply for grid. It can be controlled by changing the voltage. The above-mentioned scorotron charger as a discharger and the power supply constitute a charging device as a discharger.

By the way, discharge-producing substances such as toner and nitrogen oxides generated by electric discharge tend to adhere to the corona wire 2, and this adhesion causes discharge unevenness. Therefore, it is necessary to appropriately clean the corona wire 2. There is. Therefore, in this embodiment, a cleaning member 6 for cleaning by rubbing the corona wire 2 is provided. The cleaning member 6 is connected to the corona wire 2
In order to move the shield case 1 in a direction opposite to the photosensitive drum 4 in the direction in which the wire 1 is stretched (hereinafter referred to as a wire stretching direction), the opening 1 is opened wider than in the past.
A feed screw 5 as a guide member or a conductive member parallel to the wire extending direction is provided at b. This feed screw 5
Is located closer to the corona wire 2 than before. The feed screw 5 is made of a conductive material, for example, a metal material, and is electrically connected to the shield case 1 by abutting a leaf spring (not shown) or the like, and is grounded together with the shield case 1 to ground. Have been. Instead of directly grounding the feed screw 5 to the ground, a power source as a voltage generating means or a voltage stabilizing element such as a Zener diode may be connected to stabilize discharge. The feed screw 5 is used as a base of an insulator,
The surface may be formed of a conductive material. The feed screw 5 is connected to, for example, a motor as driving means (not shown), and rotates forward / reversely by a forward / reverse rotation of a motor drive shaft or a gear interposed between the feed screw 5 and the motor. It is configured as follows.

The cleaning member 6 includes a cleaning pad 6a, a pad holder 6b, and a slider 6c. The slider portion 6c has a cylindrical shape, and a through hole is formed from one end surface to the other end surface, and a thread is formed on a peripheral surface of the through hole so as to engage with a thread of the feed screw 5 peripheral surface. , With screw holes. Then, the thread of the slider portion 6c and the thread of the peripheral surface of the feed screw 5 engage, and the feed screw 5 is inserted into the through hole of the slider portion 6c, so that the slider portion 6c is attached to the feed screw 5. ing. Thus, the cleaning member 6 can reciprocate in the wire extending direction in accordance with the rotation of the feed screw 5.

The cleaning member 6 includes a slider 6
and c) a pad holding portion 6b formed integrally with c.
The pad holding portion 6b has a width slightly larger than the diameter of the corona wire 2 in a direction perpendicular to the wire extending direction. A cleaning pad 6a is attached to the pad holding portion 6b so as to contact the corona wire 2 with a predetermined contact pressure.

Further, in this embodiment, as a cleaning means for cleaning the surface of the feed screw 5 as a guide member or a conductive member, the cleaning means 6 is provided so as to project in the wire extending direction of the cleaning member 6 and has a diameter slightly smaller than the diameter of the feed screw 5. A pad holding portion 6d having a large width is formed, and a cleaning pad 6e is attached to the pad holding portion 6d so as to contact the feed screw 5 with a predetermined contact pressure.

In the above configuration, when the driving of the motor or the like is started as required and the feed screw 5 is rotated, the cleaning member 6 moves in the wire extending direction, and the cleaning pad 6a rubs the corona wire 2. And clean. At the same time, the cleaning pad 6e is
The surface is cleaned by rubbing.

In this embodiment, as shown in FIG.
An exhaust device 7 for discharging ozone and nitrogen oxides in the discharge device is provided. In FIG. 4, illustration of the cleaning member 6 is omitted. Exhaust device 7
Is a duct 7a connecting the upper part of the shield case 1 in which the opening 1b is formed to the outside of the machine, an electrostatic filter 7b provided in the duct 7a, an ozone decomposition filter 7c, and a machine provided outside the machine of the duct 7a. It is composed of a fan 7d for generating an airflow toward the outside of the machine. Corona wire 2
Ozone, nitrogen oxides, and the like generated in the vicinity pass through the duct 7a, the nitrogen oxides and the like are removed by the electrostatic filter 7b, the ozone is decomposed by the ozone decomposition filter 7c, and exhausted to the outside by the fan 7d. .

As described above, according to this embodiment, the metal feed screw 5 is formed in the opening 1 b formed in a part of the shield case 1.
Since the wire is extended in the direction in which the corona wire 2 is stretched and is grounded to the ground together with the shield case 1, the discharge current also flows through the feed screw 5. Discharge can be maintained, and a good image can be obtained. Also, shield case 1
Since the opening area of the opening 1b is large, the pressure loss when the gas is exhausted by the exhaust device 7 is reduced, and ozone, nitrogen oxides, and the like generated in the vicinity of the corona wire 2 can be efficiently discharged outside the machine. In addition, since the feed screw 5 is disposed closer to the corona wire 2 than before, a compact discharge device having a small dimension in the height direction can be configured. In a device including this discharge device, Effective use of space can be achieved.

According to this embodiment, the corona wire 2
The cleaning pad 6e cleans the surface of the feed screw 5 by rubbing when cleaning.
Since it is possible to prevent the surface of the feed screw 5 from being insulated by a discharge-producing substance or the like over time, the performance of the feed screw 5 as an electrode can be kept good. In particular, as in the present embodiment, when the feed screw 5 is disposed at the center of the exhaust air flow path, and when the feed screw 5 and the corona wire 2 are further close to each other,
Adhesion and contamination of nitrogen oxides and floating toner are apt to occur, but even in this case, the cleaning can prevent the surface of the feed screw 5 from being insulated.

In this embodiment, the discharge device having two corona wires 2 as the main discharge electrode member has been described. However, the number of corona wires is not limited to two, but may be one or three or more. Also, the present invention is applicable.

In this embodiment, the discharge device in which the opening 1b is provided in the back electrode of the box-shaped shield case 1 has been described. However, the opening is provided in the side electrode of the shield case 1 and the opening is provided in the opening. A feed screw 5 for guiding the cleaning member 6 may be provided, and the shield case 1 is not limited to a box shape, and may have an arc-shaped cross section.

Further, in this embodiment, the discharge device in which the guide member 5 for guiding the cleaning member 6 is disposed in the opening 1b of the shield case 1 has been described. A conductive member that is conductive may be provided in the opening 1b, and the conductive member may be configured to contact the ground directly or via a voltage generating means such as a power supply or a Zener diode.

In this embodiment, the cleaning member 6
A description has been given of the discharge device that cleans only the corona wire 2 by using the method described above. The present invention is also applicable to a discharge device configured to perform cleaning on a combination.

In this embodiment, an example is shown in which the present invention is applied to a scorotron charger of a copying machine. However, the present invention can be applied to other chargers such as a corotron charger as well as a similar configuration. The present invention can be applied to a discharge device as a transfer device or a separation device of a copying machine, or a discharge device in equipment other than the copying machine.

[0031]

According to the first aspect of the present invention, the discharge current also flows through the conductive member disposed in the opening of the shield case, so that the shield is maintained while maintaining a stable discharge. Since the opening area of the opening of the case can be increased and the pressure loss of the airflow when exhausting from the opening decreases, there is an effect that the exhaust performance can be improved.

According to the second aspect of the present invention, the discharge current also flows through the guide member disposed in the opening of the shield case, thereby maintaining the stable discharge and maintaining the height of the discharger. Since the dimension in the direction can be reduced, it is possible to reduce the size of the discharge device, and it is possible to effectively use a space in a device including the discharge device.

According to the third aspect of the present invention, by cleaning the surface of the conductive member or the guide member disposed in the opening of the shield case, the surface of the guide member due to the discharge-generating material or the like with the passage of time is cleaned. Can be prevented from being insulated, so that the conductive member or the guide member can maintain good performance as an electrode.

[Brief description of the drawings]

FIG. 1A is a front view illustrating a schematic configuration of a charger according to an embodiment. (B) is a plan view of the charger as viewed from the direction B.

FIG. 2A is a front view showing a schematic configuration of a conventional charger. (B) is a front view showing a schematic configuration of a charger according to another conventional example.

FIG. 3A is a front view illustrating a schematic configuration of a conventional charger including a cleaning member. (B) is a plan view of the charger as viewed from the direction A.

FIG. 4 is a front view of the charger and the exhaust device according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shield case 2 Corona wire 3 Grid electrode 4 Photoreceptor drum 5 Feed screw 6 Cleaning member 6a, 6e Cleaning pad 6b, 6d Pad holding part 6c Slide part 7 Exhaust device

Claims (3)

(57) [Claims] 1. A discharger comprising: a discharger having at least a shield case having an opening directed toward a discharge target, a discharge electrode stretched in the shield case, and a means for applying a voltage to the discharge electrode. in an opening formed on a part of the shield case, a part of the opening, extending in the stretched direction of the discharge electrode, <br/> one either directly or via the voltage generator A discharge device comprising a grounded metal rod . 2. A discharger having at least a shield case having an opening directed to an object to be discharged and a discharge electrode stretched in the shield case, and cleaning at least a part of members constituting the discharger. Member for guiding the cleaning member in the direction in which the discharge electrode is stretched, driving means for moving the cleaning member along the guide portion, and power supply to the discharge electrode A discharge device provided with the device, wherein an opening is formed in a part of the shield case, the guide member having at least a surface formed of a conductive material is disposed in the opening, and the guide member is directly Alternatively, the discharge device is grounded via voltage generating means. 3. The discharge device according to claim 1, further comprising cleaning means for cleaning a surface of said conductive member or guide member.