JPH04146436A - Electrostatic charger for color developer - Google Patents

Abstract

PURPOSE:To provide the electrostatic charger for a color developer which does not generate ozone, etc., by bringing a charging roller impressed with a voltage into contact with the color developer carried on a carrying roller, thereby impressing the uniform and sufficient charge to the color developer. CONSTITUTION:The color developer 3 is rubbed between a supply roller 30 and the carrying roller 10 and the triboelectrostatically charged color developer 3 is carried on the surface of the carrying roller 10 and is transported. The color developer 3 carried on the carrying roller 10 and transported by this roller comes into contact with the charging roller 20. Since the negative voltage is held impressed to the charging roller 20 at this time, a slight discharge is generated between the charging roller 20 and the grounded carrying roller 10. The discharge ions generated by this discharge are attracted to the color developer 3. Consequently, the color developr 3 is charged sufficiently to the satd. electrostatic charge quantity and forms the particles charged to a uniform negative polarity. This electrostatic charge quantity is unequivocally determined by the surface area on which the discharge ions can be attracted and, therefore, the charge stability and electrostatic charge quantity are superior to a so-called triboelectrostatic charge method.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is a method for electrostatically applying a color developer that reacts with a dye precursor to form a color onto a support such as a photosensitive pressure-sensitive medium or plain paper. This invention relates to a color developer charging device.

[Prior Art] Conventionally, an image recording apparatus using a photosensitive pressure-sensitive medium using a color developer coating method has utilized a powdered color developer. The color developer is charged and given an electric charge within the device. The color developer supported on the carrier is caused to fly under electrostatic control and is applied to a support such as a photosensitive pressure sensitive medium or plain paper.

As a charging method for this color developer, there are a method using frictional charging and a method using corona discharge.

The former method is a two-component charging method in which the mixture is charged with a so-called carrier color developer, or a one-component charging method in which the material is charged by friction with a charging member made of a polymeric material. In the latter case, a color developer is charged using a corona discharger equipped with a discharge wire.

[Problems to be Solved by the Invention] However, the above-mentioned charging method has the following problems. When using triboelectric charging, especially in the case of a -component system, it has not been possible to provide a sufficient amount of charge to the color developer, and it has also been impossible to increase the charging speed. In addition, in the case of the two-component method, although the amount of charge is relatively higher than that of the -component method, a supplementary material called a carrier is required separately, which causes many problems in terms of maintainability and economic efficiency. Further, problems common to both types using triboelectric charging include the presence of toner of opposite polarity and poor charging stability.

Further, 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 has been made to solve the above-mentioned problems, and provides a color developer charging device that imparts a homogeneous and sufficient charge to a color developer, is highly economical, and does not generate ozone, etc. is intended to provide.

[Means for Solving the Problems] In order to achieve this object, the color developer charging device of the present invention includes a color developer used for image formation, and a color developer supported on the surface of the color developer and transported. The charging roller is provided so that at least a portion of its surface is in contact with the color developer carried on the carrier and is applied with a voltage.

[Function] According to the present invention having the above configuration, when a voltage is applied to the charging roller, fine corona discharge is started between the charging roller and the carrier carrying the color developer. Ions generated by corona discharge diffuse within the color developer sandwiched between the carrier and the charging roller. The color developer becomes electrically charged by adsorbing these ions. Since the color developer 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 developer has uniform polarity and is uniformly charged. Furthermore, unlike conventional corotron discharge, since the discharge occurs in a very small space, almost all of the corona ions and ozone are adsorbed by the color developer and are not released.

Therefore, it is possible to provide a color developer charging device that imparts a uniform and sufficient charge to the color developer, is economical, and does not generate ozone.

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

First, the structure of the developer charging device fill of this embodiment will be explained with reference to FIGS. 1 and 2.

The color developer charging device 1 is roughly divided into a case 2 which is equipped with various mechanisms and houses a color developer 3, an agitator 4 provided in the case 2 and which agitates the color developer 3 stored therein, A carrier that is rotatably provided inside the case 2 and has a part exposed to the outside of the case 2, and that supports the charged color developer 3 on its surface and transports it to the outside of the case 2. A barrel carrying roller 10 is rotatably provided in the case 2, and by contacting this carrying roller 10, the color developer 3 is rubbed and supplied so that the color developer 3 is carried on the surface of the carrying roller 10. It consists of a roller 30 and a charging roller 20 which is rotatably provided in the case 2 and charges the color developer 3 carried on the surface of the carrier roller 10 uniformly and to the same polarity. There is. The color developer 3 may be a so-called insulating color developer.

The carrier roller 10 includes a roller 12 provided around a shaft 11 made of steel. The roller 12 may be made of metal, or may have a structure in which a dielectric material such as resin is disposed on a portion thereof.

The supply roller 30 triboelectrically charges the color developer 3 at a position where it contacts the carrier roller 10 by rotating in the same direction as the carrier roller 10 . The supply roller 30 is formed of a metal shaft 31 and a roller 32 arranged around it. The roller 32 is made of sponge, rubber, or the like. The carrier roller 10 and the supply roller 30 are grounded.

The charging roller 20 is connected to the carrying roller 12 as shown in FIG.
is arranged so as to be in contact with the color developer 3 carried on the surface of the color developer 3. The charging roller 20 includes a shaft 21, a conductive elastic layer 22, a medium resistance layer 23, and a protective layer 2 from the inside.
It consists of 4.

The shaft 21 is a metal shaft. The conductive elastic layer 22 is provided to maintain good contact between the charging roller 20 and the carrier roller 10 . On the top of the conductive elastic layer 22, 1
There is a medium resistance layer 23 with a resistance of 06-101° Ω/m (ohms per meter).

The medium resistance layer 23 prevents a voltage drop due to an overcurrent that occurs due to a change in the amount of color developer supported. Furthermore, the medium resistance layer 23
A protective layer 24 is arranged on the outside. This protective layer 2
4 protects the charging roller 20 and the carrying roller 10. Further, the charging roller 20 is connected to a DC power source E that generates several hundred volts. Note that the charging roller 20 is configured to rotate in the opposite direction to the carrying roller 10.

Further, a developer applying mechanism is arranged to face the developer charging device, but it is not shown because it is not the point of the present invention.

Next, the operation of the developer charging device 1 of this embodiment will be explained with reference to FIGS. 1 and 2.

When the process of applying the color developer 3 to a medium such as a photosensitive pressure sensitive medium or plain paper is started, the carrying roller 10, the charging roller 20, the supply roller 30, and the agitator 4 provided in the case 2, Rotation is started by a drive device (not shown). Then, the color developer 3 is stirred and conveyed by the rotation of the agitator 4 and sent to the supply roller 30 . Since the supply roller 30 is rotating in the same direction as the carrying roller 10 and is partially in contact with the carrying roller 10, the supply roller 30 and the carrying roller 10 are
The color developer 3 is rubbed between the rollers 10 and 10, and the frictionally charged color developer 3 is carried on the surface of the carrier roller 10 and conveyed. next,
The color developer 3 carried and conveyed by the carrying roller 10 comes into contact with the charging roller 20 .

At this time, the color developer 3 is applied to the charging roller 20 and the carrying roller 10.
However, since a negative voltage is applied to the charging roller 20, the charging roller 20 and the grounded carrier roller 10
A weak discharge occurs between the two. Discharge ions generated by this discharge are adsorbed to the color developer 3. As a result, the color developer 3 is sufficiently charged to a saturation charge amount, and becomes uniformly negatively charged particles. Since the amount of charge is uniquely determined by the surface area on which discharged ions can be adsorbed, charging stability and amount of charge are superior to that of the so-called triboelectric charging method. Further, since only a small gap exists between the carrying roller 10 and the charging roller 20, the discharged ions do not come out and are mostly adsorbed by the color developer 3. Therefore, it is possible to prevent odor caused by ozone generation, which has been a problem when conventional corona discharge was used.

Furthermore, the charged color developer 3 is held and conveyed by a carrier roller 10 and is transported outside the color developer charging device 1 . after that,
The color developer 3 flies onto a medium such as a photosensitive pressure sensitive medium or plain paper, and the color developer application process is completed.

It should be noted that the invention is not limited to the above-mentioned embodiments,
Changes may be made without departing from the spirit. For example, in this example, a negative voltage was used as the applied voltage. However, it is of course possible that a positive voltage may be used depending on the charging polarity. Furthermore, good results can be obtained even when an alternating current voltage is applied for the purpose of preventing charging unevenness.

[Effects of the Invention] As is clear from the detailed explanation above, according to the present invention, the charging roller to which a voltage is applied comes into contact with the color developer supported on the carrier, thereby causing the color developer to This has industrial advantages in that it is possible to provide a color developer charging device that imparts uniform and sufficient charging, is economical, and does not generate ozone or the like.

[Brief explanation of drawings]

1 and 2 show an embodiment embodying the present invention. FIG. 1 is a configuration diagram of a developer charging device, and FIG. 2 is a detailed perspective view of the vicinity of a charging roller. In the figure, 3 is a color developer, 1o is a carrying roller, and 20 is a charging roller.

Claims (1)

[Claims] 1. A color developer used for image formation, a carrier carrying the color developer on its surface and transporting it, and a color developer carried on the carrier and transported. 1. A color developer charging device comprising: a charging roller which is provided so that at least a part of its surface is in contact with a charging roller and to which a voltage is applied.