JP2007324372A - Nonlinear capacitor, its manufacturing method, and high-pressure metal vapor discharge lamp using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress creeping discharge caused by the lowering of insulation performance of a ferroelectric crystallized glass film in a nonlinear ceramic capacitor used for a low start voltage high pressure vapor discharge lamp. <P>SOLUTION: The nonlinear ceramic capacitor is configured as follows: electrode films 2a, 2b are formed on both surfaces of a disk shaped ferroelectric ceramic substrate used for a low start voltage high pressure vapor discharge lamp. The surfaces of these electrode films are covered with ferroelectric crystallized glass except for power supplies 6a, 6b to the electrode films and a circumferential edge of the ferroelectric ceramic substrate, and a lead wire is connected to the power supply parts to the electrode films. In the nonlinear ceramic capacitor, the thickness of coating of the ferroelectric crystallized glass is made thicker at the neighborhood of the electrode film circumferential part than at a part covering a central part of the electrode films. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention mainly relates to an improvement of a pulse generator used for starting and lighting a low starting voltage type high pressure metal vapor discharge lamp.

A low starting voltage type high pressure metal vapor discharge lamp is known as a high pressure metal vapor discharge lamp used for general lighting applications.

Since a high-pressure metal vapor discharge lamp such as a high-pressure sodium lamp generally has a high starting voltage and is difficult to start with a normal commercial power supply voltage, for example, a pulse generator is incorporated inside the discharge lamp to generate the pulse. A voltage pulse is generated by a generator, and this is applied to a discharge lamp together with a power supply voltage to start and light up.

  A nonlinear ceramic capacitor (hereinafter referred to as “FEC”) is used as a kind of pulse generator used for such applications. As an example, the present applicant has disclosed a configuration as shown in FIG. 6 (Patent Document 1). That is, the electrode films 2a and 2b are formed on both surfaces of the ferroelectric ceramic substrate 1, and the surfaces of these electrode films 2a and 2b are removed from the ferroelectric crystallized glass film 3a except for the current-carrying portions 6a and 6b. 3b, and on the outer surfaces of the glass films 3a and 3b, circular conductive films 7a and 7b are formed concentrically with the ceramic substrate 1 so as to cover the current-carrying portions 6a and 6b of the electrode film, The lead terminals 5a and 5b are fixed by the conductive adhesives 4a and 4b on the conductive films 7a and 7b avoiding the connection portion with the energization portion.

By the way, in the previously proposed FEC, the film thickness of the ferroelectric crystallized glass film becomes thinner at the outer peripheral portion thereof, and creeps along the outer edge of the FEC as the start pulse is repeatedly generated in a lamp that requires a larger start pulse energy. It has been found that discharge may occur and FEC burnout may occur.

That is, in the process of coating the ferroelectric crystallized glass, the coating material is applied so that the ferroelectric crystallized glass application part 8a has a constant film thickness as shown in FIG. The material flow occurred, and the film thickness of the outer peripheral portion of the ferroelectric crystallized glass film 3a produced after firing was relatively thinner than the central portion as shown in FIG. As a result, the insulation with respect to the pulse voltage is lowered at a part of the outer peripheral portion of the ferroelectric crystallized glass film, and the dielectric breakdown of the ferroelectric crystallized glass films 3a and 3b occurs, so that the strong resistance from the outer edge of the electrode film 2a occurs. It was confirmed that creeping discharge occurred through the outer edge of the dielectric ceramic substrate 1 to the outer edge of the electrode film 2b.

When this type of FEC is used in an atmosphere with a high vacuum inside the outer sphere and high insulation (withstand voltage), such as a high pressure sodium lamp (HPS), there are few problems. However, there are many types of metal halide lamps in which nitrogen gas is sealed in the outer bulb at about 1/2 atm. For this reason, the insulating property is lower than that of a lamp in which an outer bulb such as a high pressure sodium lamp is evacuated, and surface discharge of FEC is likely to occur through nitrogen gas.

As described above, when the FEC is housed inside the lamp outer bulb in an easy discharge atmosphere, after forming electrode films on both surfaces of the ferroelectric ceramic substrate, the ferroelectric crystal is removed except for the outer edge portion of the ceramic substrate. What coat | covered in order of the vitrified glass and the insulation reinforcement | strengthening layer is used (patent document 2).

Recently, however, new lamps with specifications that require higher starting pulse voltage and higher pulse energy, such as high-pressure steam discharge lamps and ceramic metal halide lamps having a more compact arc tube than conventional products, have appeared. Even in the case of the FEC having the configuration, the number of cases where the insulation performance of the outer edge portion is not sufficient has increased.

That is, in order to guarantee the performance of the FEC and prevent a defective product from flowing in the subsequent process, it is necessary to perform 100% inspection for confirming the performance after manufacturing. The acceptance standard value of the inspection became stricter according to the required specifications of the new lamp. For this reason, when the FEC is designed with the configuration disclosed in Patent Document 2, if any of the three types of defects, “insufficient pulse”, “surface creeping”, and “crack” is improved, other defects increase and the manufacturing yield increases. It was difficult to improve.
The present invention relates to the improvement of Patent Document 2.

Japanese Patent Laid-Open No. 2-177412 JP-A-4-62794

The present invention was made in order to solve the above-mentioned problems in the FEC proposed previously, and by setting the outer peripheral film thickness of the ferroelectric crystallized glass film to a thickness that does not cause dielectric breakdown, An object of the present invention is to provide an FEC capable of preventing dielectric breakdown at the outer peripheral portion.

  In order to achieve the above object, the present invention provides an electrode film formed on both surfaces of a disk-shaped ferroelectric ceramic substrate, and the surface of these electrode films is provided with a current-carrying portion for the electrode film and the ferroelectric ceramic substrate. In a non-linear ceramic capacitor having a hysteresis in electric field-charge characteristics, which is covered with a ferroelectric crystallized glass except for an outer peripheral portion of the electrode, and a lead wire is connected to a current-carrying portion for the electrode film, the ferroelectric crystallization It is assumed that the thickness of the coating with glass is FEC in which the portion covering the vicinity of the outer periphery of the electrode film is thicker than the portion covering the central portion of the electrode film.

In addition, in the FEC in which the ferroelectric crystallized glass is coated, the FEC is formed by further coating an insulating reinforcing layer on the coating.

In addition, as a method of manufacturing the FEC, the ferroelectric crystallized glass is applied to the same size and shape as the ferroelectric ceramic substrate in a uniform thickness, and then the ferroelectric crystal is applied only in the vicinity of the outer periphery. By applying a ferroelectric crystallized glass of the same material as the vitrified glass, followed by firing, the thickness of the coating is closer to the portion surrounding the electrode film outer peripheral portion than the portion covering the central portion of the electrode film It is set as the manufacturing method of FEC including the process of forming the film | membrane formed thickly.

Furthermore, the present invention relating to the low starting voltage type high-pressure metal vapor discharge lamp is a high-pressure metal vapor discharge lamp using the FEC.

By setting the thickness of the coating with the ferroelectric crystallized glass to be thicker at the portion covering the vicinity of the outer periphery of the electrode film than the portion covering the central portion of the electrode film, Suppresses creeping discharge through the outer edge.

Note that crystallized glass is an expensive material, and an increase in material cost can be reduced by using FEC that is additionally applied only to the outer peripheral portion.

Further, in an FEC coated with ferroelectric crystallized glass, an FEC in which an insulating reinforcing layer is further coated on the coating is used, so that it is strong even in an outer bulb of a metal halide lamp in an easy discharge atmosphere. The insulation strengthening layer coated on the dielectric crystallized glass prevents the discharge between the FEC electrodes including the creeping discharge and can surely eliminate the FEC burnout.

In addition, after applying the ferroelectric crystallized glass with the same size and shape as the ferroelectric ceramic substrate to a uniform thickness, the ferroelectric crystallized glass of the same material is applied only to the vicinity of the outer periphery, and then fired. By forming a film in which the coating thickness is thicker in the portion covering the vicinity of the outer periphery of the electrode film than in the portion covering the central portion of the electrode film, the present invention is achieved in a simple manner. The applied product can be manufactured.

Furthermore, the high-pressure metal vapor discharge lamp employing FEC manufactured by the above method eliminates the possibility of a short life due to FEC burnout and has a practically long life.

  Next, an embodiment will be described with reference to FIGS.

FIG. 1 is a partial cross-sectional view showing an embodiment of an FEC according to the present invention.
Although it is comprised with the fundamentally same member as the prior art example shown in FIG. 6, the film | membrane shape of the ferroelectric crystallized glass films 3a and 3b differs.

That is, in the FEC according to the prior art, as shown in FIG. 5, the thickness of the ferroelectric crystallized glass film 3a is reduced in the outer peripheral portion of the FEC, whereas in the FEC according to the present invention, the ferroelectric shown in FIG. Like the crystalline glass film 3a, the film thickness is thicker at the outer periphery of the FEC than at the center. Accordingly, creeping discharge does not occur from the outer edge portion of the electrode film 2a as described in the paragraph numbers 0005 and 0006 to the outer edge portion of the electrode film 2b through the outer edge portion of the ferroelectric ceramic substrate 1.

  The outermost low melting point glass films 8a and 8b are insulation reinforcing layers, and are necessary when the FEC to which the present invention is applied is used for a metal halide lamp for the same reason as described in the paragraphs 0007 and 0008. It becomes.

The FEC with the low melting point glass coated on the outermost layer tends to have a lower peak value of the generated voltage pulse than the case without the coating. Therefore, in a high pressure sodium lamp that requires a high peak voltage at the start of the lamp, It is appropriate to use FEC without a glass film.

A manufacturing method for obtaining a film shape as in the present invention will be described.
For example, as shown in FIG. 2, when a material of a ferroelectric crystallized glass film is applied to a constant film thickness using a technique such as screen printing, a ferroelectric crystallized glass application part 9 is formed on the electrode film 2a. The Further, the ferroelectric crystallized glass additional coating portion 10 is formed by coating in a ring shape so that the ferroelectric crystallized glass film material is added only in the vicinity of the outer peripheral portion.

As shown in FIG. 2, the method for applying the material of the ferroelectric crystallized glass film to a constant film thickness is not limited to the above-described screen printing method, but includes a dipping method, a spraying method, a quantitative dispenser, and a numerical control table. An interlocked coating method can also be used, but since the thickness of the insulating film greatly affects the FEC characteristics after manufacture, consideration must be given to minimize the coating amount error.

The ferroelectric crystallized glass flows by the subsequent baking process, and the shapes of the ferroelectric crystallized glass application part 9 and the ferroelectric crystallized glass additional application part 10 shown in FIG. 2 change. As a result, the shape of the ferroelectric crystallized glass film 3a after firing is such that the outer peripheral insulating layer is reliably thicker than the central portion as shown in FIG. 3, and creeping discharge from the outer edge portion can be suppressed.

Actually, the film thickness of the ferroelectric crystallized glass film 3a may be relatively thin. As an example, when the manufacturing method of the present invention is applied to an FEC having a thickness of the ferroelectric ceramic substrate 1 of 1.0 mm, the ferroelectric crystallized glass film 3a has a maximum film thickness near the outer periphery. At 32 μm, the thickness of the other part was 25 μm. The FEC of this specification not only passed the characteristic confirmation test of the FEC alone, but also had a good life test result when incorporated in a metal halide lamp.

By adopting the configuration of the present invention, creeping discharge from the outer edge of the FEC is suppressed, and therefore, among the three types of defects of “insufficient pulse”, “creeping discharge”, and “crack” described in paragraph 0010, creeping The restrictions on electric discharge have been relaxed, and it has become possible to design FECs that can generate more pulses than are required for new lamps and are less likely to crack. Therefore, in the 100% inspection with the same reference value as the paragraph number 0010, the defect rate can be greatly reduced.

  The present invention is a technique that prevents the FEC from being burned out by creeping discharge at the outer edge of the FEC, and enables the FEC to be used even for a new high-pressure metal vapor discharge lamp that requires a higher voltage or higher energy starting pulse.

1 is a partial cross-sectional view showing an embodiment according to the present invention. The partial cross section figure for demonstrating the manufacturing method which concerns on this invention. The partial cross section figure for demonstrating the manufacturing method which concerns on this invention. The partial cross section figure for demonstrating the manufacturing method which concerns on a prior art. The partial cross section figure for demonstrating the manufacturing method which concerns on a prior art. The partial cross section figure which shows the Example which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ferroelectric ceramic substrate 2a, 2b Electrode film | membrane 3a, 3b Ferroelectric crystallized glass film | membrane 4a, 4b Conductive adhesive agent 5a, 5b Lead terminal 6a, 6b Current supply part 7a, 7b Electrode film | membrane 8a, 8b Low Melting point glass coating 9 Ferroelectric crystallized glass application part 10 Ferroelectric crystallized glass additional application part

Claims (4)

Electrode films are formed on both surfaces of a disk-shaped ferroelectric ceramic substrate, and the surfaces of these electrode films are ferroelectric except for the current-carrying portion for the electrode film and the outer peripheral edge of the ferroelectric ceramic substrate. In a non-linear ceramic capacitor that is covered with crystallized glass and has a lead wire connected to a current-carrying portion with respect to the electrode film and exhibits hysteresis in electric field-charge characteristics, the thickness of the coating with the ferroelectric crystallized glass is the center of the electrode film A nonlinear ceramic capacitor in which a portion covering the vicinity of the outer peripheral portion of the electrode film is formed thicker than a portion covering the portion.
2. The non-linear ceramic capacitor according to claim 1, wherein an insulating reinforcing layer is further coated on the coating with the ferroelectric crystallized glass.
3. A method of manufacturing a nonlinear ceramic capacitor according to claim 1 or 2, wherein the ferroelectric crystallized glass is coated in a uniform thickness with the same size and shape as the ferroelectric ceramic substrate, and then an outer peripheral portion. By applying a ferroelectric crystallized glass of the same material as that of the ferroelectric crystallized glass only in the vicinity, and then firing, the thickness of the coating is greater than the part covering the central part of the electrode film. A method of manufacturing a non-linear ceramic capacitor including a step of forming a film in which a portion covering the vicinity of the portion is formed thicker.
A high-pressure metal vapor discharge lamp using the nonlinear ceramic capacitor according to claim 1 or 2.

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