JPS6251463A - Electric discharge device - Google Patents

Abstract

PURPOSE:To increase ion extraction efficiency by providing the second electrode interposed with a dielectric material isolated from a pair of first electrodes installed with an interposed dielectric material and applying an alternate voltage between the first electrodes. CONSTITUTION:If an alternate voltage is applied between electrodes 1-1, 1-2, a positive and a negative ion generate in the opening of an electrode 2. Since the negative DC voltage is applied to an electrode 3, only the negative ion passes through an opening 14, reaching a static recording medium 20. When 'hi' signal is transmitted to the electrode 2 from an image signal source 18, the negative ion is discharged between the electrode 2 and the electrode 3, because the potential of the former is higher than that of the latter. This does not allow the negative ion to reach the static recording medium 20. In the meantime, if 'lo' signal is transmitted from the image signal source 18, the negative ion, attracted by the potential of a conductive member 21, is charged with a solid dielectric 22, adhering to the static recording medium 20, because of the lower potential of the electrode 2 than that of the electrode 3. Thus it is possible to extract an adequate quantity of ions, even if the ion generation volume per cycle were reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge device and an electrostatic recording device using the same.

11. As shown in FIG.
A discharge device is disclosed in, for example, US Patent No. It is known as disclosed in Japanese Patent No. 4,155,093. A bias voltage is applied between the electrode 2 and the member to be charged 20, thereby extracting only ions of a specific polarity among the positive Q negative ions and directing them toward the member to be charged, thereby charging the member to be charged. Can be charged to desired polarity.

Furthermore, as shown in FIG. 2, an electrostatic recording device using this is also known, as disclosed in, for example, US Pat. No. 4,160,257.

This electrostatic recording device includes a plurality of first electrodes 1 extending in a first direction, a second electrode 2 extending in a direction different from the first direction and forming a matrix together with the first electrode 1, and the second electrode 1 extending in a first direction. a third electrode 3 provided on the opposite side of the first electrode l with respect to the electrode 2 and having an opening corresponding to the matrix; a first dielectric 11 between the first electrode 1 and the second electrode 2; ,
The first electrode 1 is selected in a time-sharing manner using a recording head having a second dielectric 12 provided between the second electrode 2 and the third electrode 3 and having a plurality of openings 14 corresponding to the matrix. Then, an alternating voltage is sequentially applied between the selected first electrode 1 and the second electrode 2, and the second electrode 2 and the first dielectric 11
Ions are generated by electric discharge between the surface of the recording material and the recording material. forming a digital charge pattern on the surface of the

All of these methods are considered to be useful, but each method has the disadvantage that ions of both polarities are generated and only ions of one polarity are extracted from these, resulting in poor extraction efficiency.

Therefore, an object of the present invention is to provide a discharge device with high ion extraction efficiency.

According to the present invention, a pair of first electrodes are provided with a dielectric material interposed therebetween, and a first electrode is provided separated from each of the pair of electrodes and with a dielectric material interposed therebetween. There is provided a discharge device characterized by having means for applying an alternating voltage between a second electrode and a pair of first electrodes, so that ions of a desired constant polarity can be generated in any cycle of the alternating voltage. can be extracted and the ion extraction efficiency can be increased.

Strut 1 FIG. 3 is a sectional view of a discharge device according to an embodiment of the present invention. The discharge device has a pair of first electrodes 1-1 and 1-2, a second electrode 2, a dielectric 11 and an alternating piezoelectric [16].

The first electrodes 1-1 and 1-2 have a thin plate shape and are embedded in the dielectric 11 at a distance. -Therefore, the first electrode 1-
In this embodiment, a dielectric material is interposed between the first electrode 1-1 and the first electrode 1-2.
are provided on the same plane.

The second electrode 2 is fixed to the bottom surface of the dielectric 11 and exposed to the outside. Therefore, the first electrode 1-1 and the second electrode 2
A dielectric material is also interposed between the first electrode 1-2 and the second electrode 2. As described later, the first electrode 1-1 and the first electrode 1-2 are connected to the alternating voltage power source 16, but the second electrode 2 is not electrically connected to any of the other elements. It is said to be electrically floating.

The material of the first electrode 1-1.1-2 and the second electrode 2 is a conductive metal, such as nickel, stainless steel, tungsten, gold, or nickel-plated copper.

As the material of the dielectric 11, for example, an inorganic material such as ceramic, mica, or glass, or an organic polymer material such as polyimide, Teflon, polyester, or polyimide is used.

An alternating voltage power source 1 is connected between the pair of first electrodes 1-1 and 1-2.
Alternating voltages are applied by 6. Here, the waveform of the alternating voltage is a sine wave, a rectangular wave, a pulse wave,
When an alternating voltage, such as a triangular wave, is applied between the pair of first electrodes by the alternating voltage power supply 16, the second electrode
A glow discharge occurs in the air gap between both sides of the electrode 2 and the bottom surface of the dielectric 11, and positive and negative ions are generated. The second electrode 2 is in an electrically floating state as described above.

They are simply coupled capacitively. This second electrode 2
The effects are as follows. Considering the configuration without the second electrode 2, a fairly high alternating voltage is applied between the two hot electrodes in order to form a sufficient electric field to initiate a glow discharge in the air gap on the dielectric surface adjacent to the first electrode. Alternatively, it is necessary to place the two hot electrodes close to each other, and in this case, the problem of dielectric breakdown between the two cylinder electrodes occurs. By providing the electrodes, we have substantially reduced the distance between the first electrodes, which increases the electric field strength so that, at relatively low alternating voltages, the air between the dielectric surface and the second electrode is Since an electric field sufficient for dielectric breakdown of the air is formed in the gap, a glow discharge starts at a relatively low alternating voltage, and positive and negative ions are generated.

FIG. 4 shows a case where a member to be charged 20 is charged by this discharge device. The member to be charged 20 is arranged opposite to the second electrode 2 of the discharge device, and the member to be charged 20 is connected to a conductive member 21. A solid dielectric 22 is provided, and the solid dielectric 22 is installed facing the second electrode 2 . A bias voltage is applied between the second electrode 2 and the conductive member 21 by a bias power supply 17 . Due to the electric field formed by this bias power supply 17, among the ions generated in the vicinity of the second electrode 2, ions with a polarity determined by the direction of the bias electric field move toward the solid dielectric 22, causing the solid dielectric 22 to be Charged with polarity.

FIG. 5 is a perspective view of the configuration of FIG. 4. Along with the above ion generation and ion movement operations, the charged member 20
It moves in the direction of the arrow in the figure by a drive mechanism (not shown), and charges the surface of the member to be charged 20 .

Next, the mechanism of ion generation in the discharge device of this embodiment will be explained in detail.

FIG. 6 is a schematic diagram for understanding the electrical connection relationship of the discharge device of this embodiment. First electrode 1-1 and first electrode 1-
Since there is a dielectric material between the electrodes 2 and 2 as described above, these electrodes are electrically connected via the equivalent capacitance C1.

Furthermore, since this is done through the dielectric 11 between the first electrode 1-1 and the second electrode 2 and the air gap between the bottom surface of the dielectric 11 and the second electrode 2, the equivalent capacitance C2
and C3.

FIG. 7 shows this as an electric circuit. An electric field sufficient for dielectric breakdown of the air is formed in the air gap,
When discharge occurs, the equivalent capacitance C3 is short-circuited, so the capacitance C3
A Zener diode is connected in parallel to 3.

FIGS. 8 and 9 explain the mechanism of ion generation in the conventional discharge device shown in FIG.
Figure 8 shows the phase in which a positive voltage is applied to the upper electrode;
The figure shows the electric field lines and the movement of ions in opposite phases; as can be seen, the direction of the electric field lines on both sides of the bottom electrode is the same in each phase, and therefore the extraction in each phase For example, in the phase shown in FIG. 8, the lines of electric force are directed toward the lower electrode, and only negative ions that move in the opposite vector to the lines of electric force can be extracted. This is true for both left and right sides of the lower electrode. Therefore, in the phase shown in FIG. 8, only negative ions can be extracted, and in the phase shown in FIG. 9, only positive ions can be extracted.

FIGS. 10 and 11 illustrate the direction of the electric lines of force between the electrodes and the generated ions at two different phases of the alternating voltage applied by the alternating voltage power supply 16 in an embodiment of the present invention.

FIG. 1O shows the phase in which a positive voltage is applied to the first electrode 1-2, and FIG. 11 shows the state in the opposite phase. As understood from these figures, the second electrode 2
The directions of the electric lines of force on both sides (left and right sides in the figure) are opposite to each other, regardless of the phase of the alternating voltages. As a result, in the case of positive ion extraction, for example, positive ions move in the direction of the electric field lines, so the second
If there are electric lines of force from the electrode 2 to the surface of the dielectric 11,
Positive ions can be extracted and the electric field lines are present on either side of the second electrode 2 in either phase, as can be seen from the figure. Therefore, positive ions can be extracted in either phase. It is understood from these figures that negative ions can be extracted as long as there are electric lines of force in the opposite direction, and that these also exist in any phase.

12 and 13 show an embodiment in which the discharge device of the present invention is used in an electrostatic recording head. be.

This recording head includes a first electrode 1-1, 1-2, a second electrode 2, a third electrode 3, a first galvanic body 11, and a second galvanic body 12.
has.

There are a plurality of pairs of first electrodes 1-1 and 1-2, which extend in a first direction (horizontal direction in FIG. 12). Second
The electrodes 2 are also arranged in a plurality of stages, and these extend in a direction different from the first direction described above, forming a matrix together with the first electrode pair. The third electrode 3 ′ is connected to the second electrode 2
On the other hand, the first electrode pair is provided oppositely to the first electrode pair. Third
The electrode 3 has openings 4 corresponding to the intersections of the matrix.

The first dielectric 11 is at least the same as the first electrode 1-1 and 1-2.
A dielectric material is interposed between them and the second electrode 2, and the second J electric body 12 is sandwiched between the second electrode 2 and the third electrode 3. The second dielectric 12 has a plurality of openings 14 corresponding to the matrix, which openings 14 are aligned with the openings 4 .

An alternating voltage power source 16 is connected between the first electrode 1-1 and the first electrode 1-2.
is connected, and the second electrode 2 is connected to the image signal source 18. The third electrode 3 is connected to a bias power supply 17 and a constant bias voltage is applied thereto. A cylindrical electrostatic recording medium 20 is installed facing the recording head, that is, facing the third electrode 3, and the electrostatic recording medium 20 has a conductive member 21 and a solid dielectric material 22 on top of the conductive member 21. In operation An alternating voltage is applied between the two first electrodes 1-1 and 1-2. Specifically, alternating voltages are sequentially applied to a plurality of pairs of first electrodes in a time-sharing manner, and positive and negative ions are generated at the openings of the second electrodes 2 in the rows to which this voltage is applied. In this embodiment, a negative DC voltage is applied to the third electrode 3 as shown in the figure, so that only the negative ions among the generated positive and negative ions pass through the opening 14 and pass through the electrostatic recording medium. It can reach 20. The positive ions are discharged and extinguished between the third electrode 3 and do not contribute to electrostatic recording.

A high or low signal is applied to the second electrode 2 from an image signal source 18 . When a high signal is output, the potential of the second electrode 2 is higher than the potential of the third electrode 3, so negative ions are discharged between the third electrode 3 and do not reach the electrostatic recording medium 20. on the other hand.

When a low signal is output from the image signal source 18, the second electrode 2
Since the electric potential of When 600V is applied, the image signal is -750V.
By applying a voltage of -600V, the circuit is turned on, and by applying a voltage of -600V or less, it is turned off. In this way, negative ions adhere to the electrostatic recording medium 20 in response to the low signal from the image signal source 18. For example, an I MHz sine wave is used as the alternating voltage.

The electrostatic recording medium 20 rotates in the direction of the arrow in FIG. 13, and alternating voltages are sequentially applied to the plurality of first electrodes 1 in a time-division manner at a speed synchronized with this rotational speed. Then, by applying a low signal to a desired one of the apertures 14 corresponding to the intersections of the matrix, negative ions adhere to the electrostatic recording medium 20 in the form of an image, and an electrostatic latent image is obtained.

Improving ion extraction efficiency is particularly important in digital latent image formation using these ions. In order to create high-definition digital images, it is necessary to reduce the area of the electrostatic charge dots formed on the recording medium, but if the ion extraction efficiency is poor, the amount of ions generated by one discharge, that is, the ion density, will increase. It was found that increasing the ion density increases the self-field strength and tends to cause the ions to diffuse. Therefore, large electrostatic dots are formed on the recording material, making it impossible to obtain high-definition images.

According to the present invention, since the ion extraction effect is high, it is possible to obtain a constant charge even if the amount of ions generated by -times of discharge, and therefore the ion density, is suppressed.

FIG. 14 is a plan view of an electrostatic recording head according to another embodiment of the present invention. In this embodiment, adjacent first electrodes are commonly used to form a single electrode. 1-2 is used for its upper second electrode and its lower second electrode. The rest of the configuration is the same as the embodiment shown in FIGS. 12 and 13, so detailed explanation will be omitted. This makes it possible to reduce the matrix spacing in the recording material moving direction.

FIG. 15 shows a cross-sectional view of an electrostatic recording device using the electrostatic recording head of the present invention. The body 22 rotates in the direction of the arrow. First, the solid dielectric 22 is subjected to the action of AC corona electricity removal, and electricity is removed so that its surface potential becomes approximately Ov. As explained above, an electrostatic latent image is formed on the solid dielectric material 22 by the electrostatic recording head in accordance with the image signal. This latent image is a digital charge pattern consisting of a collection of charge dots of negative polarity, for example, as pixels. This latent image is developed by a developing device 32. In this embodiment, the developing device has a positive polarity one-component insulating toner (for example, Japanese Patent Publication No. 58-32375).
Here, the distance between the developing sleeve, which is a developer carrier of the developing device, and the surface of the solid dielectric material is approximately 3004 m, and a bias voltage is applied to the sleeve by a power source (not shown). The bias voltage is 2~3KHz, 1000~150
AC of 0Vpp (peak to peak value) and -10 to -5
This is a superimposed 0V direct current. The developing device is not limited to this, and the one described in Japanese Patent Application Laid-open No. 118060/1983 can also be used. In this method, a grid is provided between a solid dielectric material and a developing sleeve, and an alternating voltage is applied between them, so that the toner powder cloud generated is attracted to the latent image by the electric field generated by the latent image. ,
In this case as well, the toner powder cloud does not reach the mesh. As a method for forming the powder cloud, ultrasonic waves may be used, or a well-known two-component developer method may be used.The developed image is transported by a transporting means (not shown) by a transfer charger. The image is transferred to a recording paper 34.

The recording material to which the toner image has been transferred undergoes image fixation by a fixing device, and is then discharged outside the apparatus.

On the other hand, the surface of the solid dielectric after the transfer is cleaned by the cleaning means 35, and the toner that has not been transferred is removed from the solid dielectric 22.

The solid dielectric material 22 after cleaning is subjected to the action of the static eliminator 36, and after the static electricity is removed, it becomes ready for the next image formation.
The recording action is repeated.

According to the present invention, as explained above, ion extraction ・
A highly efficient discharge device is provided, which allows sufficient ions to be extracted even though the amount of ions generated per cycle is reduced. Furthermore, when this is used in an electrostatic recording head, it becomes possible to produce high-definition images due to improved ion extraction efficiency.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional discharge device. FIG. 2 is a sectional view of a conventional electrostatic recording head using the discharge shown in FIG. FIG. 3 is a sectional view of a discharge device according to an embodiment of the present invention. FIG. 4 is a sectional view showing a configuration in which a member to be charged is charged by the discharge device shown in FIG. 3. FIG. FIG. 5 is a perspective view of the configuration shown in FIG. 4. FIG. 6 shows the electrical equivalent connection relationship of the discharge device of FIG. 2. FIG. 7 is an equivalent circuit diagram based on FIG. 6. FIGS. 8 and 9 are cross-sectional views showing the state of ion generation and movement in a conventional discharge device. FIGS. 10 and 11 are cross-sectional views showing the state of ion generation and movement in the embodiment of the present invention. FIG. 12 is a plan view of an embodiment in which the present invention is used in an electrostatic recording head. FIG. 13 is a sectional view taken along line XIII-XIII in FIG. 12. FIG. 14 is a plan view of an electrostatic recording head according to another embodiment of the present invention. FIG. 15 is a sectional view of an example of an image forming apparatus using the electrostatic recording head of the present invention. Figure 4: First dielectric 2: Second dielectric 10: First dielectric 11: Dielectric 12: Second dielectric 13: First dielectric 14: Opening 15: First dielectric Body 16: Alternating voltage power supply 17: Bias power supply 18: Image signal source 19: First dielectric 20: Second dielectric 21: Conductive member 22: Solid dielectric Fig. 1 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Figure v, Figure 8 Figure 9 Figure 12 Figure 13 Cause Figure 14 Figure 115 Cause

Claims (1)

[Scope of Claims] A pair of first electrodes provided with a dielectric material interposed therebetween, and a second electrode provided spaced apart from each of the pair of electrodes and with a dielectric material interposed therebetween. A discharge device comprising: an electrode; and means for applying an alternating voltage between the pair of first electrodes.