JPH02196671A - ionography head - Google Patents

Abstract

PURPOSE:To obtain an ionography head which does not generate a noise in a peripheral electric circuit and is driven at a low voltage by composing a second electrode of a plurality of electrode groups separated from each other, and providing means for varying the distance between the electrode of the electrode group and a first electrode independently. CONSTITUTION:An insulating board 11 is secured with a piezoelectric element 13 interposed between electrodes 12 and 14. Further, an electrode 2 is secured to the electrode 13 through an insulating layer 15. A piezoelectric element driving circuit 16 can apply a voltage to the piezoelectric element driving electrodes 12, 14 of the electrode 2. When the voltage is applied, the piezoelectric element 13 is elongated in an electrode direction, and an interval between the electrodes 1 and 2 is narrowed. When the interval between the electrodes is shortened, a critical voltage between the electrodes becomes lower than the voltage applied between the electrode 1 and the electrode 2, a partial discharging is started to charge an insulating substance 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ionographic head used for image formation in an electrostatic image forming apparatus.

[Conventional technology] The conventional ionography head is Nat i.

nal Technical Report V
ol 24 No 4 Aug 1978
p674-p684. 3rd Non-Impact Printing Technology Symposium Collection of Papers p145~
As stated in page 148, it was necessary to apply a high voltage to each discharge electrode or extraction electrode of each pixel.

[Problems to be Solved by the Invention] However, the above-mentioned conventional technology has a problem in that high voltage is applied to a plurality of electrodes, which causes noise in the surrounding electric circuits.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an ionographic head that is driven at a low voltage and does not cause noise in the surrounding electrical circuits.

[Means for solving the problem] The second electrode is composed of a plurality of electrode groups separated from each other,
Each electrode of the electrode group is characterized in that it has means for independently changing the distance from the first electrode.

[Function] According to the above structure of the present invention, an ionographic head can be realized by driving the electrodes corresponding to each pixel at a low voltage.

In the ionographic head of the present invention, a DC voltage is applied between the first electrode, which serves as an ion generation source, and the second electrode, which serves as a counter electrode. FIG. 5 is a voltage-current characteristic diagram between the electrodes. In Figure 5, the curve L-1 has an inter-electrode distance of d.
This is a voltage-current characteristic curve when l is a certain value, a-1 is the critical voltage at which discharge starts, and a-2 is the threshold voltage at which partial discharge transitions to total circuit breakdown, that is, spark discharge. .

When the distance between the electrodes becomes d2 (di>d2), the curve showing the voltage-current characteristics shifts to L-2. Therefore, the critical voltage at which discharge occurs between the electrodes also changes to a-3, and the threshold voltage at which total circuit breakdown occurs also changes to a-4.

If the value of the voltage applied between the ion generating electrode and the counter electrode is set to a-11 (a-3<a-11<a-1), when the distance between the electrodes becomes d2, a- 11 is the critical voltage a-
Since it exceeds 3, partial discharge occurs between the electrodes. When the distance between the electrodes returns to dl, the voltage applied between the electrodes a-1
1 becomes below the critical voltage and the discharge stops.

[Example] Hereinafter, the present invention will be explained in detail based on examples.

FIG. 1 is a schematic diagram of an ionographic head in an embodiment of the present invention. In FIG. 6, 1 is a linear electrode, and 2 is a linear electrode.
The electrode groups are opposite electrodes each corresponding to one pixel and are alternately arranged in rows on both sides with the electrode 1 in between. Metals such as tungsten and tungsten alloys are generally used as materials constituting the electrodes. Voltage 1,
A DC voltage is applied between 2 and 2. Each of the electrodes 2 shortens the distance from the electrode 1 by independently applying a voltage to the piezoelectric element on the substrate side to generate a discharge, and the discharge between the electrodes 1 and 2 is caused by the insulating material 4 adjacent to them. to be charged.

FIG. 2 is a cross-sectional view of the ionographic head of Example 1. In FIG.
The piezoelectric element 13 sandwiched between is fixed. Furthermore, electrode 1
The electrode 2 is fixed to 3 through an insulating layer 15. In the figure, 16 is a piezoelectric element drive circuit, which can apply a voltage to each of the piezoelectric element drive electrodes 12 and 14 of the electrodes 2. When a voltage is applied, the piezoelectric element 13 expands in the direction of the electrodes, and the distance between the electrodes 1 and 2 becomes narrower. As the distance between the electrodes becomes shorter, the critical voltage between the electrodes becomes lower than the voltage applied between the electrodes 1 and 2, starting a partial discharge and charging the insulating material 4.

FIG. 3 is a schematic diagram of an ionography head in another embodiment of the present invention. In FIG. 1, reference numeral 21 indicates a substrate 22 having a shape in which needle-like electrodes protrude from linear electrodes at a pixel pitch.
It is fixed to . The electrode groups 23 each have opposing electrodes corresponding to one pixel, and are arranged in a line at the pixel pitch, and are fixed so as to face the protruding portions of the electrodes 21. Electrode 21
A voltage is applied between the electrodes 23 and 23 by a voltage source 32. In the figure, 25 is an insulating sheet that passes between the electrodes 21 and 23.

FIG. 4 is a cross-sectional view of the ionographic head in Example 2. In FIG.
．． A piezoelectric element 28 held between 29 is fixed. Further, the electrode 23 is fixed to the electrode 29 via an insulating layer 30. In the figure, 31 is a drive circuit for the piezoelectric element, which applies a voltage between the piezoelectric element drive electrodes 27 and 29 of each of the electrodes 23. Can be done. When a voltage is applied to the electrodes 27 and 29, the piezoelectric element 28 expands in the direction of the electrodes, and the distance between the electrodes 21 and 23 narrows, causing a partial discharge in the electrodes.The partial discharge generated near the electrodes 22 is insulating. The sheet 25 is charged.

Note that the means for moving the second electrode is not limited to the method using the piezoelectric element shown in the above-mentioned embodiments, but may also be performed using other microactuators. Examples 1 and 2
In both cases, the shape of the insulating material is effective for drum-like, sheet-like, and other shapes. Further, in both Examples 1 and 2, the counter electrode group may be configured in one row or in two rows depending on the density thereof.

[Effects of the Invention] As described above, according to the present invention, in order to generate an ion current positionally, wiring for each unit position is not required for the ion generation electrode or extraction electrode, and the ion flow can be easily structured. This has the advantage that a graphics head can provide this.

FIG. 4 is a sectional view of the ionography head in Example 2, and FIG. 5 is a voltage-current characteristic diagram between electrodes.

1... Linear electrode 2...Counter electrode 3. Voltage source 13...Piezoelectric element 16... Drive circuit that's all Applicant: Seiko Epson Corporation

Claims (3)

[Claims] (1) a first electrode that generates at least an ion flow;
In an ionography head comprising a second electrode opposite to the first electrode, and a third electrode that selectively extracts the ion flow according to an image signal, the second electrode An ionographic head comprising a plurality of electrode groups separated from each other, each electrode of the electrode group having means for independently changing the distance from the first electrode. (2) The ionographic head according to claim 1, wherein the first electrode and the second electrode are on the same side with respect to an insulating layer forming an electrostatic latent image. (3) The ionographic head according to claim 1, wherein the first electrode and the second electrode are located on both sides of an insulating layer that forms an electrostatic latent image.