JPH04143777A - Powder electrostatic charging device - Google Patents

Abstract

PURPOSE:To perform the electrostatic charging of powder uniformly and sufficiently and to eliminate the problem of ozone, etc., by providing an electrostatic charging electrode which is incorporated in a powder container and has a thin wire type discharging electrode applied partially with a voltage. CONSTITUTION:Toner 5, a carrier 8, and the electrostatic charging electrode 4 are incorporated in the container 1, which consists of a grounded conductor. The electrostatic charging electrode 4 consists of a base shaft 3 and discharging electrodes 2, which are arranged on the base shaft 3 and made of a conductor, e.g. a discharging material with small deterioration such as a stainless steel wire. When the discharging electrodes 2 start corona discharge with the grounded powder container, ions generated by the corona discharge are diffused in the powder container and the powder put in the container is charged electrostatically by adsorbing those ions; and the corona ions and ozone are almost all adsorbed by the powder and never discharged. Consequently, the electrostatic charging is performed uniform and sufficiently and the electrostatic charging device which is free from the problem of ozone, etc., is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a powder charging device for charging powder such as toner.

[Prior Art] Powder-like particles have conventionally been used in electrophotographic image recording devices and image recording devices using color developer-coated photosensitive and pressure-sensitive media. The powder is triboelectrically charged within each device. By applying electrostatic control suitable for each, the powder flies and is formed as an image. In particular, conventional methods for charging this powder include methods that utilize frictional charging and methods that utilize corona discharge. The former includes a so-called two-component charging method in which a carrier powder is mixed and charged, and a charging part of a polymer charge +
There is a one-component charging method that uses frictional charging. In the latter case, a corona discharger with a discharge wire is used to charge the powder.

[Problems to be Solved by the Invention] However, the following problems have occurred in the above-mentioned charging method. When using triboelectric charging,
In particular, when using the -component method, it was possible to provide a sufficient charging portion to the powder, but it was also not possible to increase the charging speed. In the case of the two-component method, the amount of charge is relatively higher than that of the -component method, but a supplementary material called a gear is required separately, which has recently become a problem in terms of maintainability and economic efficiency.

In addition, problems common to both types using triboelectric charging include the presence or generation of toner of opposite polarity and poor charging stability.

In addition, when corona discharge is used, although the charging polarity and the amount of charging are satisfactory, there is a problem in that ozone is generated and a strange odor is felt.

The present invention was made to solve the above-mentioned problems, and its purpose is to impart a uniform and sufficient charge to powder, eliminate problems such as ozone, and eliminate consumables. The object of the present invention is to provide an economical powder charging device.

[Means for Solving the Problems] In order to achieve this object, the powder charging device of the present invention includes a powder container that is grounded, and a powder container that is built in the powder container, and a voltage is applied to at least a part of the powder container. It is composed of a charging electrode having a thin wire-shaped discharge electrode. The powder container is grounded, and the charging electrode is built in the powder container and has a thin wire-shaped discharge electrode to which a voltage is applied to at least a portion of the charging electrode.

[Effect] The present invention having the above configuration performs the following operations.

A voltage is applied to the charging electrode. Then, the discharge electrode attached to the charging electrode starts corona discharge between the grounded powder containers. Ions generated by corona discharge diffuse inside the powder container. The powder contained in the container becomes electrically charged by adsorbing these ions. Since the powder has a surface area that corresponds to the particle size, the ion adsorption surface is also made constant. Furthermore, the ions have uniform polarity. Therefore, the powder has uniform polarity and is uniformly charged.

Furthermore, unlike conventional corotron discharge, since the discharge is performed in a nearly sealed container, almost all of the corona ions and ozone are adsorbed by the powder and are not released.

Therefore, it is possible to provide a charging device that can uniformly and sufficiently charge powder and is free from problems such as ozone. Furthermore, by eliminating consumables, a highly economical device can be provided.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a powder charging device according to an embodiment of the present invention. Inside the container 1, a toner 5, a carrier 8, and a charging electrode 4 are contained. The container 1 is made of a grounded conductor. The toner 5 may be a so-called insulating powder and may be an electrophotographic toner or a color developer toner. The charging electrode 4 is composed of a base shaft 3 and a discharge electrode 2. The base shaft 3 is made of a conductive shaft such as steel or aluminum, and is connected to a power source that generates a positive voltage. A discharge electrode 2 is arranged on the base shaft 3. The discharge electrode 2 is made of a conductor, such as stainless steel wire, niobium, tantalum, zirconium, or other material that is suitable for use as a discharge material and has little deterioration.

The discharge electrode 2 may have a diameter of about several tens of microns and a length of several mm. A voltage is also applied to the discharge electrode 2 by the power source E.

The charging electrode 4 is rotatable. and discharge electrode 2
is arranged with a slight gap between it and the container 1.

Further, there is a carrier 8 which is arranged to protrude from the container 1. The carrier 8 is made up of a roller 6 and a shaft 7. Both may be made of conductors or insulators, but they are connected to the optimal potential depending on the conditions. Furthermore, a well-known electrophotographic process device and a developer coating process device (not shown) are arranged around the carrier 8.

Next, the operation of the present invention will be explained.

The carrier 8 contained within the container 1 and the charging electrode 4 begin to function. That is, both begin to rotate and voltage is also applied. A positive voltage is applied to the discharge electrode 2, and a corona discharge is started between the discharge electrode 2 and the grounded container 1. At this time, corona ions are generated by the discharge. These ions are physically adsorbed to the toner 5.

The discharge electrode 2 is always rotating and close to the container 1 to continue discharging. As a result, the toner 5 increases to a sufficiently saturated charge amount and becomes uniformly positively charged particles. Since this amount of charge is uniquely determined by the surface area on which corona ions can be adsorbed, the charging stability and amount of charge are more stable than in the so-called triboelectric charging method.

Furthermore, since only a very small gap exists around the carrier 8, the corona ions do not come out from inside the charger and are absorbed by the toner 5. Therefore, it is possible to sufficiently prevent the odor caused by ozone generation, which was a problem when conventional corona discharge was used. The charged toner 5 is held by a roller 6. Then, it is rotated and transported outside the charger. Thereafter, in the case of an electrophotographic apparatus, the toner 5 flies to a photoreceptor, and a developing process is performed.

In the case of a developer coating device, the developer is sprayed onto the photosensitive pressure sensitive medium (7 coating steps are completed).

Next, a second embodiment of the present invention will be briefly described.

FIG. 2 is a sectional view showing a second embodiment of the invention. As in the first embodiment, a toner 15, a charging electrode 14, a carrier 18, a partition wall 19, etc. are arranged in a container 11. The partition wall 19 is a so-called mesh-like screen, and the toner 5
prevent the entry of

The charging electrode 14 is composed of a base shaft 13 and a discharge electrode 12. Further, the carrier is composed of a roller 16 and a shaft 17.

When this device is started, corona discharge occurs between the discharge electrode 12 and the container 11. The corona ions pass through the partition wall 19 and land on the toner 15. Toner 15 produces good effects similar to the first embodiment described above.

[Effects of the Invention] As is clear from the detailed description above, according to the present invention, when a voltage is applied to the charged electrode, the discharge electrode attached to the charged electrode connects between the grounded powder container and the corona. Discharge begins, and ions generated by corona discharge diffuse within the powder container. The powder contained in the container becomes electrically charged by adsorbing these ions. Since the powder has a surface area corresponding to the particle size, the ion adsorption surface is also made constant. Furthermore, the ions have uniform polarity. Therefore, the powder has uniform polarity and is uniformly charged. Furthermore, unlike conventional corotron discharge, since the discharge is performed in a nearly sealed container, almost all of the corona ions and ozone are adsorbed by the powder and are not released.

Therefore, it is possible to provide a charging device that can uniformly and sufficiently charge powder and is free from problems such as ozone. Furthermore, by eliminating consumables, it can be made more economical and inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a powder charging device according to a first embodiment of the present invention, and FIG. 2 is a schematic sectional view showing a second embodiment of the present invention. In the figure, 1 and 11 are powder containers, 2 and 12 are discharge electrodes, 4,
14 is a charging electrode, 5.15 is a toner, and 8.18 is a carrier.

Claims (1)

[Claims] 1. Consisting of a grounded powder container, and a charging electrode having a thin wire-shaped discharge electrode built into the powder container and to which a voltage is applied to at least a portion thereof. A powder charging device characterized by: