Electricity: electrical systems and devices – Electric charge generating or conducting means
Patent
1980-03-11
1982-06-15
Miller, J. D.
Electricity: electrical systems and devices
Electric charge generating or conducting means
250325, 355 3CH, H01T 1904
Patent
active
043354203
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a corona discharge device of the scorotron system used for electrophotographic copying machines, which requires only one connector that connects to a corona discharge wire, and which is adapted to be easily positioned with respect to the main body and is adapted to prevent poor electrical connection.
2. Description of the Prior Art
Corotron and scorotron have widely been known as corona discharge devices. In particular, the scorotron charger has been frequently employed as a discharge device for negatively charging owing to its small dispersion in discharge performance. With regard to the construction, however, a connector for grid wires is separately provided from a connector for corona discharge wire, such that the grid wires are impressed with a constant voltage from an external power supply. Since at least two or more connectors are necessary, the shape of the connector portion tends to become complex. Besides, the device requires clumsy positioning operation and imposes a problem of poor connection.
In view of such circumstances, the object of the present invention is to provide a corona discharge device which requires only one connector to facilitate the positioning operation as well as to prevent the occurrence of poor connection.
SUMMARY OF INVENTION
The present invention deals with a corona discharge device comprising a discharger having a wire for corona discharging, an electrically conductive shielding plate and grid wires; and an impedance element which is connected in series between the grid wires and the ground and which generates a voltage responsive to a corona current flowing into the grid wires; wherein the impedance element is connected between the grid wires and the electrically conductive shielding plate and is formed as a unitary structure in the discharger. Thus, since the impedance element is connected between the grid wires and the electrically conductive shielding plate and is formed as a unitary structure together with the discharger, the connector is needed only for the corona discharge wire, enabling the positioning operation to be facilitated and poor connection to be prevented.
Furthermore, according to the present invention, the impedance of the impedance element is made variable to compensate the aging of photosensitive materials, as well as to change the picture characteristics .
BRIEF DESCRIPTION OF THE DRAWINGS
The drawings illustrate an embodiment according to the present invention; in which;
FIG. 1 is a plan view;
FIG. 2 is a side view of FIG. 1;
FIG. 3 is a plan view showing, in a partially cut-away manner, the device of the invention on an enlarged scale;
FIG. 4 is a vertically cut-away side view on an enlarged scale;
FIG. 5 is a vertically cut-away front view;
FIG. 6 is a vertically cut-away front view showing a modified embodiment; and
FIG. 7 is a diagram illustrating characteristics.
DETAILED DESCRIPTION
An embodiment of the invention is illustrated below with reference to the drawings. Referring, first, to FIGS. 1 to 4, a casing 3 which serves as an electrically conductive shielding plate is formed in a ]-shape by a back plate 1 and side plates 2 (refer to FIG. 5). On both sides of the casing 3 are provided electrically insulating brackets 4 and 5 across which are stretched a plurality of grid wires 6 which are located on the open side of the casing 3 and are pulled by spring 7. Further, nearly at the center of the casing 3, a corona discharge wire 8 is stretched being pulled by a spring 9 between the brackets 4 and 5 in the lengthwise direction of the casing 3. Thus, a discharger 10 of the scorotron system is constructed by the casing 3, grid wires 6 and corona discharge wire 8. A constant-voltage element 11 which is an impedance element is provided at one end of the casing 3. One end of the constant-voltage element 11 is connected to the ends on one side of the grid wires 6, and the other end thereof is connected to the side plate 2. To the other end of the casing 3
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patent: 4233511 (1980-11-01), Harada et al.
Kazuaki Tagawa
Mitsuo Tanaka
Takashi Yano
Miller J. D.
Ricoh Co. Ltd.
Schroeder L. C.
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