JPH0897069A - High breakdown voltage capacitor - Google Patents

Abstract

PURPOSE: To obtain a capacitor endurable against high voltage and high current at low cost by employing quartz as a dielectric between conductors. CONSTITUTION: Tubular inner conductor 2 and outer conductor 3 are secured, respectively, to the inner and outer circumferential surfaces of a tubular quartz tube 1. The inner and outer conductors 2, 3 are made of copper or aluminum. The tubular quartz tube 1 is employed as a dielectric. When the capacitor is employed in the lighting unit for electrodeless high luminance discharge lamp where a high voltage is applied at the time of starting, the inner and outer conductors 2, 3 are coated, at the edges thereof, with insulation films 4, 5 of silicon rubber, or the like, in order to prevent corona discharge from taking place thereat. This structure realizes a high quality capacitor durable against high voltage and high current easily. Furthermore, a compact capacitor having variable capacitance can be constituted easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a high voltage capacitor,
In particular, the present invention relates to a high withstand voltage capacitor used in a lighting device for an electrodeless high intensity discharge (HID) lamp.

[0002]

2. Description of the Related Art A high-intensity discharge lamp is one in which metal ions are excited by a current flowing in a high-pressure ionized gas such as mercury or sodium vapor to emit visible light, and this excitation is generally performed between two electrodes. It is generated by applying a voltage to and applying a current. By the way, various main electrodeless high-intensity discharge lamps have been proposed, which have the advantage that the main cause of the failure in the high-intensity discharge lamp having such a structure is the electrodes, and therefore there is no phenomenon of life due to the electrodes.

FIG. 5 is a diagram showing a configuration example of a conventional lighting device for an electrodeless high-intensity discharge lamp. 101 is a high frequency power supply,
102 is an electrodeless high-intensity discharge lamp, L is a coupling coil (excitation coil) for supplying electric power to the electrodeless high-intensity discharge lamp 2, C2 is a capacitor connected in parallel with the coupling coil and forming a parallel resonance circuit, C1 Is a capacitor that determines the degree of coupling between the parallel resonant circuit and the high frequency power supply 1.

In the electrodeless high-intensity discharge lamp lighting device having such a structure, when high-frequency power is supplied from the high-frequency power supply 101, the parallel resonance circuit composed of the coupling coil L and the capacitor C2 is supplied with the power supply voltage Q ( Resonance circuit quality
factor) times the voltage is induced, and a strong solenoidal electric field is generated in the enclosed gas of the discharge lamp 102. This solenoidal electric field is formed by the changing magnetic field in the coupling coil L. In this state, when a discharge seed is applied to the discharge lamp, a toroidal arc discharge is started. When the discharge is started, the inductance due to the arc discharge in the discharge lamp is added to the coupling coil L, and the capacitor C2 needs to be reduced,
The capacitor C1 needs to be increased in order to supply more power to the discharge lamp. Particularly, at the time of starting, a high voltage of several thousand volts is applied to the capacitors C1 and C2.
C2 must be of high quality with high breakdown voltage and small dielectric loss.

[0005]

As a high withstand voltage capacitor used in the electrodeless high-intensity discharge lamp lighting device having the above-described structure, there is also a method of using a large number of standard RF (high frequency) capacitors connected in parallel and in series. However, in this case, there is a drawback that the loss of the lead wire and the like becomes large. Further, although the vacuum capacitor has a high withstand voltage characteristic, there is a problem that it is not only very expensive but also becomes large in size.

The present invention has been made in order to solve the above-mentioned problems in conventional high voltage capacitors, and an object thereof is to provide a capacitor that can withstand high voltage and high current at low cost.

[0007]

In order to solve the above problems, the present invention constitutes a high voltage withstanding capacitor by using quartz as a dielectric material interposed between conductors.

As described above, since quartz used as a dielectric has excellent withstand voltage and heat resistance and a small dielectric loss, it is possible to endure a high voltage and a high current and easily realize a high-quality capacitor. Further, by forming the dielectric made of quartz in a cylindrical shape, it is possible to easily accommodate a compact and variable capacitance type.

[0009]

EXAMPLES Next, examples will be described. 1 (A) and 1 (B) show a first high withstand voltage capacitor according to the present invention.
It is the external view and sectional drawing which show an Example. In the figure, 1
Is a cylindrical quartz tube, and cylindrical inner conductors 2 and outer conductors 3 are fixedly provided on the inner peripheral surface and the outer peripheral surface of the quartz tube 1, respectively. Copper is the most suitable material for the inner conductor 2 and the outer conductor 3, but other metals such as aluminum can also be used. When it is used in a lighting device for an electrodeless high-intensity discharge lamp, a high voltage is applied at the time of starting, so that corona discharge does not occur at the edge portions of the inner conductor 2 and the outer conductor 3 so that they do not occur at the edge portions. Insulating films 4 and 5 made of silicon rubber or the like (not shown in FIG. 1A) are applied and formed.

Since the cylindrical quartz tube 1 is used as a dielectric in this way, it is possible to easily realize a compact capacitor having high withstand voltage and high current.

Next, a second embodiment will be described. Figure 2
(A) and (B) are an external view and a cross-sectional view showing a second embodiment, and the same or corresponding members as those of the first embodiment shown in (A) and (B) of FIG. Is attached.
In this embodiment, a sliding inner conductor 6 having a spherical tip and a cylindrical tip is slidably arranged inside a cylindrical quartz tube 1.

Since the slidable inner conductor 6 is slidably arranged inside the cylindrical quartz tube 1 as described above, the outer conductor 3 is formed.
It is possible to change the electrostatic capacity by changing the facing area with, and thus to form a variable capacitor,
Further, since the tip of the sliding type internal conductor 6 is spherical,
Corona discharge can be effectively prevented.

Next, a third embodiment will be described. Figure 3
(A) and (B) are an external view and a cross-sectional view showing a third embodiment, and the same or corresponding members as those of the first embodiment shown in (A) and (B) of FIG. Is attached.
This embodiment is shown inside the fixed cylindrical inner conductor 2 of the first embodiment shown in FIGS. 1A and 1B, and further shown in FIGS. 2A and 2B. Sliding inner conductor 6 of the second embodiment
The sliding-type internal conductor 7 having a spherical tip and a cylindrical shape and having the same structure as the above is slidably arranged. In the third embodiment, it is possible to realize a fixed capacitor whose capacitance is partially variable.

Next, a fourth embodiment will be described. Figure 4
(A) and (B) are an external view and a sectional view showing a third embodiment, and (A) and (B) of FIG. 1 to (A) and (B) of FIG.
Members which are the same as or correspond to those in the respective embodiments shown in are designated by the same reference numerals. In this embodiment, the outer conductor 3 is commonly used, and one side of the quartz tube 1 has a structure shown in FIG.
The sliding-type inner conductor 6 of the second embodiment shown in FIG. 3B is slidably arranged, and the other side of the quartz tube 1 has a structure shown in FIG.
The internal conductor 2 of the third embodiment shown in (B) and the sliding type internal conductor 7 slidably disposed inside the internal conductor 2 are arranged.

In this embodiment, the variable capacitor and the partially variable fixed capacitor can be integrally formed. For example, two capacitors C1 and C2 in the electrodeless high-intensity discharge lamp lighting device shown in FIG.
When used as, since the external conductor 3 is shared, the parasitic inductance due to the lead wire can be reduced and the Q of the resonance circuit can be further increased. Moreover, the impedance matching state of the lighting circuit can be accurately adjusted by adjusting the variable capacitance.

[0016]

As described above on the basis of the embodiments,
According to the present invention, since quartz having excellent withstand voltage and heat resistance and low dielectric loss is used as the dielectric, it is possible to easily realize a high-quality capacitor that can withstand high voltage and high current. Further, by forming the dielectric made of quartz into a cylindrical shape, a compact and variable capacitance type can be easily constructed.

[Brief description of drawings]

FIG. 1 is an external view and a sectional view showing a first embodiment of a high voltage capacitor according to the present invention.

FIG. 2 is an external view and a cross-sectional view showing a second embodiment.

FIG. 3 is an external view and a sectional view showing a third embodiment.

FIG. 4 is an external view and a sectional view showing a fourth embodiment.

FIG. 5 is a diagram showing a configuration example of a conventional electrodeless high-intensity discharge lamp lighting device.

[Explanation of symbols]

 1 Cylindrical Quartz Tube 2 Inner Conductor 3 Outer Conductor 4,5 Insulating Film 6,7 Sliding Type Inner Conductor

Claims (7)

[Claims] 1. A high withstand voltage capacitor characterized in that quartz is used as a dielectric interposed between conductors. 2. The dielectric material made of quartz is formed in a cylindrical shape, and an inner conductor and an outer conductor are provided on an inner peripheral surface and an outer peripheral surface of the cylindrical dielectric material, respectively. High voltage capacitor. 3. The inner conductor and the outer conductor are formed of copper or aluminum.
High-voltage capacitor described. 4. The high breakdown voltage capacitor according to claim 2, wherein the inner conductor and the outer conductor are fixedly arranged. 5. The high breakdown voltage capacitor according to claim 2, wherein the inner conductor or the outer conductor is movably arranged. 6. The high withstand voltage capacitor according to claim 2, wherein the inner conductor includes a fixed arrangement portion and a movable arrangement portion. 7. The high withstand voltage capacitor according to claim 2, wherein the inner conductor is composed of a first inner conductor and a second inner conductor which are separated from each other.