JPH0594078A - Electrostatic charging device - Google Patents

Abstract

PURPOSE:To perform discharge even at low voltage, to sufficiently electrostatically charge a photosensitive body and to reduce the quantity of ozone and nitrogen oxide produced by discharge in an electrostatic charging device for electrostatically charging the photosensitive body by the discharge. CONSTITUTION:In the electrostatic charging device for electrostatically charging an image carrier such as the photosensitive body 1 by the discharge, an insulating substrata 12, many projecting electrodes 11 which are provided to be projected in a cone shape on the insulating substrate 12, a counter electrode 14 provided by interposing a specified gap between the electrodes 11 and 14, and a voltage impressing means for impressing the voltage to cause the discharge between the electrodes 11 and 14 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device used for charging an image bearing member such as a photoconductor in an electrophotographic apparatus such as a copying machine or a printer, and more particularly, to a photoconductor such as a photoconductor by discharging. The present invention relates to a charging device that charges an image carrier.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic apparatus such as a copying machine or a printer, various charging devices have been used to charge a photoconductor to form an image.

Here, as a charging device for charging the photoreceptor as described above, a corotron charger or a scorotron charger is generally used in the past, and such a charging device performs corona discharge. It was designed to charge the photoreceptor.

However, when performing corona discharge using a corotron charger or a scorotron charger, a very high voltage is required to perform the discharge, and the cost required for the power source and the like is high, and such a high voltage is also required. When a corona discharge is performed in this way, this discharge causes a lot of ozone and nitrogen oxides, which have been a problem in recent years.
There was a problem of harming the environment.

On the other hand, in recent years, in order to suppress the generation of ozone, nitrogen oxides, etc. when charging the photoreceptor as described above, it has been considered to use a charging device other than a corotron charger or a scorotron charger. For example, as disclosed in Japanese Patent Application Laid-Open No. 57-78582, one in which a conductive brush is contacted with the surface of the photoconductor to charge the photoconductor, or a conductive roller is contacted with the surface of the photoconductor. A contact type device has been developed in which a conductive member is brought into contact with the surface of the photoconductor to charge the photoconductor, such as one in which the photoconductor is charged.

However, when the conductive brush or the conductive roller is brought into contact with the surface of the photoconductor to charge the photoconductor as described above, the surface of the photoconductor is deteriorated by such contact, and the photoconductor's surface is deteriorated. There is a problem that streaky noise is generated because charging is not performed uniformly.

[0007]

SUMMARY OF THE INVENTION The present invention has various problems as described above in a charging device used for charging an image carrier such as a photoconductor in an electrophotographic apparatus such as a copying machine or a printer. The problem is to solve.

Further, in the present invention, the image carrier such as the photoconductor is not contact type in which the electroconductive brush or the electroconductive roller is brought into contact to charge the photoconductor as described above, but non-contact discharge. In a charging device that is designed to charge, the discharge is performed even at a low voltage so that the photoconductor is sufficiently charged and the generation of ozone, nitrogen oxides, etc. due to the discharge is reduced. This is an issue.

[0009]

According to the present invention, in order to solve the above problems, in a charging device for charging an image carrier by electric discharge, an insulating base and a large number of insulating bases are provided on the insulating base. A protruding electrode protruding in a cone shape, a counter electrode provided so as to be spaced apart from each of the protruding electrodes by a required distance, and a voltage for applying a voltage to generate a discharge between the protruding electrode and the counter electrode. The application means is provided.

Here, when the protruding electrode protruding in a cone shape is provided on the insulating substrate as described above, the protruding electrode can be generally provided by a method such as vacuum deposition, electron beam, ion assist, and ICB.

The materials used for such electrodes are chromium, copper, tungsten, aluminum, gold,
A metal such as platinum, indium or titanium, or a conductive material such as ITO or carbon can be used.

Further, as the above-mentioned cone-shaped protrusion electrodes, in addition to the bottom electrode having a circular shape,
A polygonal shape such as a triangle, a quadrangle, a hexagon, or an octagon may be used.

Here, in forming the protruding electrode having a circular bottom surface, as shown in FIG. 1, the length a of the bottom portion of the protruding electrode 11 and the protruding height of the protruding electrode 11 are formed. The relationship with h is preferably 3h <a <50h, more preferably 5h <a <
Try to satisfy the relationship of 30h. This is because when the height h of the protruding electrode 11 is too large with respect to the length a of the bottom portion, the protruding electrode 11 becomes brittle, and the protruding electrode 11 is vaporized and evaporated by discharge, and the life of the protruding electrode 11 is shortened. And conversely with respect to the length a of the bottom side, the protruding electrode 1
This is because if the height h of 1 is small, the discharge is unlikely to occur, a high voltage is required to perform the discharge, and the discharge becomes unstable.

Further, in order to enable stable use of the protruding electrode formed on the insulating substrate as described above for a long period of time, the surface of the protruding electrode is formed of a metal oxide-based inorganic thin film or a diamond-like carbon film. It is preferable to coat.

Further, in order to generate a discharge between the protruding electrode and the counter electrode, the voltage applied between the protruding electrode and the counter electrode by the voltage applying means is DC, AC or a combination of DC and AC. It may be any of the voltages.

Further, in this way, when the voltage is applied between the projecting electrode and the counter electrode by the voltage applying means to discharge, and thereby the image carrier is charged,
It is preferable to provide a blowing unit that sends the charged gas generated by this discharge to the image carrier side.

[0017]

In the charging device according to the present invention, a large number of protruding electrodes are provided so as to project in a cone shape on the insulating substrate as described above, and the protruding electrodes are provided so as to be spaced apart from each other by a required distance. A voltage for discharging is applied from the voltage applying means to the counter electrode to discharge between the projecting electrode and the counter electrode, and the image carrier is charged by the charging gas generated by this discharge. To

Here, when a discharge is generated between the protruding electrode protruding in a cone shape and the counter electrode as described above, the protruding electrode and the counter electrode are different from those of the conventional corotron charger or scorotron charger. Even if the voltage applied during the period is low, sufficient discharge is performed, the image carrier is sufficiently charged, and ozone and nitrogen oxides due to the discharge are reduced.

Further, by providing the air blowing means for sending the charged gas generated by the discharge between the protruding electrode and the counter electrode to the image carrier side as described above, the charging efficiency of the photosensitive member is further improved.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A charging device according to an embodiment of the present invention will be specifically described below with reference to the accompanying drawings.

In this embodiment, when a large number of protruding electrodes 11 protruding in a cone shape are provided on the insulating substrate 12, a vacuum vapor deposition device 20 as shown in FIG. 2 is used.

Here, in the vacuum vapor deposition apparatus 20, a tray 22 provided at the bottom of the apparatus main body 21.
A vapor deposition source 22 made of a conductive material such as chromium used for forming the protruding electrode 11 is set on a, and a guard portion 23 is provided around the vapor deposition source 22 and a shutter 24 is provided above the vapor deposition source 22. I did it.

Further, the insulating substrate 12 is arranged at a position above the shutter 24 in the main body 11 of the apparatus through a pattern mask 25 having a large number of holes 25a as shown in FIG. ..

Then, the inside of the main body 21 of the apparatus is 10 ⁻⁶ To
When the vapor pressure is 10 ^-4 T or less, a voltage is applied from a power source (not shown) to the saucer 22a on which the vapor deposition source 22 is set to evaporate the vapor deposition source 22.
orr or less, and while rotating the pattern mask 25 and the insulating substrate 12 in a tilted state as shown in FIG. 2, the insulating substrate is passed through the plurality of holes 25a provided in the pattern mask 25. The vapor deposition material 22 was vapor-deposited on 12 and was made to grow gradually in a cone shape.

In this way, in this embodiment, as shown in FIG. 4, a large number of protruding electrodes 11 protruding in a cone shape are provided in a line on the insulating substrate 12, and each protruding electrode 11 is provided.
Are connected by the lead electrode 13.

On the other hand, as described above, the counter electrode 1 is provided with a predetermined gap from each protruding electrode 11 provided on the insulating substrate 12.
4 may be provided by using, as the counter electrode 14, the pattern mask 25 itself used when the protruding electrode 11 is formed as described above, but in this embodiment, as shown in FIG. The insulating base 12
A large number of holes 15a are provided in the elongated flat plate member 15 so as to correspond to the protruding electrodes 11 provided above, and each of the holes 15a
An electrode 14a was provided around a, and each of these electrodes 14a was connected by an extraction electrode 14b.

Then, the insulating substrate 12 provided with a large number of cone-shaped protruding electrodes 11 as described above is set on the support member 16, and the inside is hollow on the insulating substrate 12 set in this way. The spacer member 17 is formed, and the flat plate member 15 in which the electrodes 14a are provided around the large number of holes 15a as described above is set on the spacer member 17 so as to face each protruding electrode 11. Electrode 14
Are provided via a required interval. In this embodiment, the distance d ₁ shown in FIG. 5 is 10
˜100 μm.

Next, a case will be described in which an image is formed by charging the photoconductor 1 with the charging device 10 of this embodiment formed as described above.

Here, as the photosensitive member 1 charged by the charging device 10 of this embodiment, as shown in FIG. 6, a belt-shaped photosensitive member 1 wound around a rotating roller 31 is used.

The cone-shaped protruding electrode 11 of the charging device 10 faces the belt-shaped photosensitive member 1 so that the charging device 10 is spaced from the belt-shaped photosensitive member 1 at a constant interval. I decided to provide it.

Here, in providing the charging device 10 with the belt-shaped photoconductor 1 at a constant interval,
As shown in FIGS. 6 and 7, at the position facing the charging device 10, a positioning roller 32 is provided on the back surface side of the belt-shaped photoconductor 1 and the longitudinal end portion of the charging device 10 slides. An insulating spacer 33 made of a good material is provided so as to project toward the photoconductor 1.

Then, the charging device 10 is pushed toward the photoconductor 1 by the biasing member 34 such as a spring, and the side end of the photoconductor 1 in the form of a belt is moved by the positioning roller 32 and the insulating spacer 33. The insulating spacer 33 adjusts the distance between the photoconductor 1 and the charging device 10 so that the distance is about 0.02 to 1 mm, and the charging device 10 protrudes in a cone shape. The electrode 11 was provided so as to face the photoconductor 1.

In the charging device 10, a large number of projecting electrodes 11 are provided so as to project in a cone shape as described above, and a counter electrode 14 is provided between the projecting electrodes 11 with a required space. In the meantime, a voltage of 700 V to 2 KV was applied from a power source (not shown) to cause discharge between each protruding electrode 11 and the counter electrode 14, thereby charging the photoreceptor 1.

When the photoconductor 1 was charged as described above, the surface potential of the photoconductor 1 was 400 V to 1 KV, and the photoconductor 1 was sufficiently charged.

When the surface of the photoconductor 1 is charged in this manner, the same state as when the photoconductor 1 is charged by applying a voltage of 4 to 8 KV to a commonly used scorotron charger. Further, the photoreceptor 1 is charged, and the amount of gas such as ozone and nitrogen oxide generated by the discharge is 1/30 or less as compared with the case where the scorotron charger is used.

After the surface of the photoconductor 1 is charged by the charging device 10 in this way, the surface of the photoconductor 1 thus charged is exposed by suitable exposure means 2 based on image information, An electrostatic latent image is formed on the surface of the photoconductor 1, and toner is supplied from the developing device 3 to the surface of the photoconductor 1 on which the electrostatic latent image is formed, so that a toner image is formed. ..

After the toner image is formed on the surface of the photoconductor 1 in this way, the toner image formed on the surface of the photoconductor 1 is transferred onto the recording paper 5 via the transfer roller 4, and The recording paper 5 on which the toner image has been transferred is guided to a fixing device (not shown) to fix the transferred toner image on the recording paper 5, while the toner image remains on the surface of the photoconductor 1 to which the toner image has been transferred. The cleaning device 6 to remove the remaining toner,
After that, the surface of the photoconductor 1 was irradiated with light from the eraser lamp 7 to eliminate the charge on the surface of the photoconductor 1, and then the photoconductor 1 was charged again by the charging device 10.

Here, as a result of continuing the image formation as described above, when toner or the like adheres to the protruding electrodes 11 and the counter electrode 14 of the charging device 10 and the electrodes 11 and 14 are contaminated. The electrodes 11 and 14
A bias voltage having a polarity opposite to that of the case of charging the photoconductor 1 is applied between the electrodes 11 and 14, and the toner and the like attached to the electrodes 11 and 14 are blown from the electrodes 11 and 14 to the photoconductor 1 side. The toner and the like applied to the surface of the photoconductor 1 in this way are removed from the surface of the photoconductor 1 by the cleaning device 6.

Here, the charging device 10 of this embodiment is used.
Although the case where the belt-shaped photoconductor 1 is charged has been described above, it is naturally possible to charge the drum-shaped photoconductor 1.

Further, in the charging device 10 of this embodiment, as shown in FIG. 8, it is arranged between the insulating substrate 12 provided with the protruding electrode 11 and the flat plate member 15 provided with the counter electrode 14. An air circulation nozzle 18 for guiding air is provided in the formed spacer member 17.
Air is introduced into the spacer member 17 by means of the above, and the charged gas generated by the discharge between the protruding electrode 11 and the counter electrode 14 is taken together with the air thus introduced to the counter electrode 14
By feeding the light to the surface of the photoconductor 1 through the hole 25a provided in the photoconductor 1, the charging efficiency of the photoconductor 1 is further improved.

In the charging device 10 of this embodiment, a large number of cone-shaped protruding electrodes 11 are provided in a row as described above, but such protruding electrodes 11 are insulated. It is also possible to use a zigzag pattern on the base 12 and a plurality of rows provided.

Further, in this embodiment, the counter electrode 14 facing each protruding electrode 11 is provided with the spacer member 1.
Although it is arranged to be provided via 7, it is shown in FIGS. 9 (A) and 9 (B).
As shown in, it is also possible to provide the counter electrode 14 around the protruding electrode 11 provided on the insulating substrate 12 with a required space. When the counter electrode 14 is provided around the protruding electrode 11 provided on the insulating substrate 12 with a required space, the distance d ₂ between the protruding electrode 11 and the counter electrode 14 is about 10 to 40 μm. I liked it.

[0043]

As described above in detail, in the charging device according to the present invention, a large number of projecting electrodes provided so as to project in a cone shape on the insulating substrate, and the required spacing between the projecting electrodes. Since a voltage is applied from the voltage applying means to the counter electrode provided so as to intervene to discharge between the protruding electrode and the counter electrode, a conventional corotron charger or scorotron charger is used. Compared with the above, the discharge is performed at a lower voltage, and thus the image carrier such as the photoconductor is sufficiently charged.

As a result, when the charging device according to the present invention is used to charge the image carrier, the image carrier can be sufficiently charged at a low voltage, and the cost required for the power source and the like. And the generation of harmful substances such as ozone and nitrogen oxides generated by discharge was reduced.

In the charging device of the present invention, the voltage applied from the voltage applying means between the projecting electrode and the counter electrode for discharging and the distance between the projecting electrode and the counter electrode are changed. It can also be used as a transfer charger or a charge removal charger.

[Brief description of drawings]

FIG. 1 is a side view showing a state of a protruding electrode used in a charging device of the present invention.

FIG. 2 is a schematic explanatory view of a vacuum vapor deposition apparatus used for forming a protruding electrode in a cone shape on an insulating substrate in an embodiment of the present invention.

FIG. 3 is a perspective view of a pattern mask used to provide cone-shaped protruding electrodes on an insulating substrate in an embodiment of the present invention.

FIG. 4 is an exploded perspective view of the charging device according to the embodiment of the present invention.

FIG. 5 is a partial explanatory view of the charging device according to the embodiment of the present invention.

FIG. 6 is a schematic explanatory view showing a state in which an image carrier is charged by the charging device according to the embodiment of the present invention to form an image.

FIG. 7 is a partially enlarged explanatory view showing a state in which the charging device of this embodiment is provided with an image carrier with a constant space.

FIG. 8 is a perspective view showing a state in which the charging device according to the embodiment of the present invention is provided with an air circulation nozzle for sending the charging gas generated by the discharge to the image carrier side.

FIG. 9 is an explanatory diagram showing a modified example of the charging device of the present invention.

[Explanation of symbols]

 1 Image Carrier 10 Charging Device 11 Projecting Electrode 12 Insulating Substrate 14 Counter Electrode

Claims (1)

[Claims] 1. A charging device for charging an image carrier by electric discharge, comprising an insulating substrate, a large number of cone-shaped protruding electrodes provided on the insulating substrate, and a predetermined space between each protruding electrode. A charging device comprising: a counter electrode thus provided; and a voltage applying means for applying a voltage to generate a discharge between the protruding electrode and the counter electrode.