JPS60136151A - High pressure electric-discharge lamp - Google Patents

Abstract

PURPOSE:To prevent any breakage of the glass bulb and any burning of the stabilizer which might occur in the last stage of the life of a high pressure electric-discharge lamp by properly selecting the structure and dimensions of a highly-dielectric ceramic capacitor which constitutes a starter. CONSTITUTION:In order to prevent the electrostatic radiation of electrons, the electric field of the electrode film surface is decreased by coating the base body of a ceramic capacitor 2 with a material having a higher electric constant than the base body. During the usual lighting of a high pressure electric-discharge lamp, any electric discharge in the ceramic capacitor 2 can be prevented by properly selecting the distance between the periphery of silver film electrodes 8a and 8b and the periphery of a ceramic base plate, the thickness of a highly-dielectric crystalline glass film and several factors including the partial pressure of xenon gas in the internal atmosphere. Owing to the above constitution, it is possible to prevent any breakage of the glass bulb and any burning of the stabilizer which might occur in the last stage of the life of the lamp.

Description

Detailed Description of the Invention A. Field of Industrial Application This invention relates to the improvement of high-pressure discharge lamps such as high-pressure sodium lamps used for general lighting, and in particular to the improvement of high-pressure discharge lamps with a starting device housed inside the outer bulb. It is about improvement.

High-pressure emission lamps such as prior art high-pressure sodium lamps are difficult to start with normal commercial power supply voltage, and require the application of a high-voltage pulse voltage to start them. Lamps in which a device for generating such a pulse voltage is installed inside the outer bulb of the lamp and are used in combination with a general high-pressure mercury lamp ballast have become popular. 1 and 2 are circuit diagrams of such a lamp. This lamp basically consists of an arc tube 1 and a ferroelectric ceramic capacitor 2 connected in parallel, which is connected to a semiconductor switch 3.
A high voltage pulse voltage is generated by combining it with a diode 4, and is applied to the arc tube 1 together with the starting pressure to start the lamp. By the way, in order to start such a high-pressure sodium lamp, it is generally necessary to apply a pulse voltage having a peak value of 2000 V or more, although it depends on the xenon gas pressure in the light emitting C1 that constitutes this lamp. . It is effective to use a ferroelectric ceramic capacitor as a means for stably generating such a high pulse voltage.

This capacitor has D (charge)-E (coercive electric field) characteristics as shown in FIG. By utilizing the rectangular characteristics of this capacitor to perform a switching action, it is possible to generate the above-mentioned high-voltage pulse voltage.

Although generation of such a high-pressure pulse voltage is very effective for starting a high-pressure sodium lamp, it is necessary to consider problems that occur at the end of the life of a high-pressure sodium lamp. That is, in general, pressure sodium lamps tend to leak at the electrode seal part of the arc tube 1 at the end of their life, and this can cause xenon gas, sodium, and mercury in the arc tube 1 to come out into the outer bulb 5. many. In this case, since the inside of the lamp's outer bulb is in a high vacuum, when a pulse voltage is applied to the lamp, a discharge starts throughout the lamp's outer bulb, and naturally a large current accompanying arc discharge is generated. flows. If this condition continues for a long time, the ballast 6 installed outside the lamp may be burnt out, and, most dangerously, the outer bulb 5 may be damaged by the arc inside the outer bulb. .

C. Purpose of the Invention The present invention has been made in view of the above points, and is a high-pressure discharge lamp equipped with a safety function to prevent damage to the glass bulb or burnout of the ballast at the end of the lamp's life. The purpose is to provide In order to achieve this objective, the present invention has a receptacle structure that destroys the ferroelectric ceramic capacitor that constitutes the starter device against the leakage of xenon gas into the outer bulb due to leakage of the arc tube at the end of its life. It is characterized by:

Structure of the Invention An example of the circuit structure of the high pressure discharge lamp according to the present invention is as shown in FIGS. 1 and 2, and a specific example of the structure is as shown in FIG. 3.

In each case, a ferroelectric ceramic capacitor 2 is connected in parallel with the arc tube 1, and these are housed in an outer bulb 5 whose interior is kept in a high vacuum. The above-mentioned ferroelectric ceramic capacitor 2 is generally made by adding several moles of strontium titanate, zirconium-plated barium, barium stannate, etc., and a trace amount of rare earth oxide powder to barium ditanate powder, and granulating it into a disk shape. A ceramic substrate 7 as shown in FIG. 5 is produced by press molding and firing in air, and electrode films 8a and 8b are formed on both surfaces of the ceramic substrate 7 using silver paste or the like. This is overcoated with ferroelectric crystallized glass paste 9 except for the lead terminal portions, and then lead terminals 10a110b are adhered to the lead wire terminal portions. The above-mentioned ferroelectric crystallized glass paste 9 for overcoat is literally xBaTi03+ (17x)Ba/Igz, 5
The dielectric constant ε can be set to 300 to 1200 depending on the firing temperature and its holding time. If the capacitor is housed in the outer bulb without an overcoat as described above, discharge will occur from the entire surface or edge of the silver film electrode when a high voltage pulse is generated, which may damage the electrode film or damage the ceramic substrate. I will destroy it. This is because the high electric field is narrow and concentrated on the electrode film, and the silver
Since the k-electrode itself is mixed with oxide, that is, glass frit, the function of the silver film electrode itself is low.
This is because the electric field emission of electrons becomes easier. In order to prevent such electric field radiation, as described above, the electric field on the surface of the electrode J can be lowered by overcoating the base of the ceramic capacitor with a material having a higher dioptric index. In other words, one such capacitor
When using this method, factors such as the distance between the periphery of the silver j imitation electrode and the temporary periphery of the ceramic 2F, the thickness of the ferroelectric crystallized glass film, and the gysenon gas pressure as the atmosphere should be selected appropriately. This prevents discharge in the ceramic capacitor during normal lighting of the high-pressure discharge lamp, and at the end of the lamp's life, it can conversely cause electrical protection and destroy the suppressing pulse voltage generation function. Therefore, among the above factors, the inventors focused on the fact that the distance between the periphery of the silver film electrode and the periphery of the ceramic substrate had a particularly large effect, and conducted the following experiment on discharge breakdown of a capacitor.

As the ceramic substrate 7 shown in FIG. 5, a barium titanate-based material having nonlinear characteristics as described above was fired, and a disc-shaped material with a diameter of 26.0 mm and a J thickness of 5 mm was used. Periphery of ceramic substrate 7 and silver film electrode 8
a, the circumference 1 of 8b, the distance d from the house, the thickness t1 of the ferroelectric crystallized glass 9, and the xenon gas pressure inside the outer sphere with this capacitor set (4) to generate a high-voltage pulse pressure. The state of discharge breakdown of capacitors was investigated.The results of the experiment were as shown below.The table showing the actual test results is shown below.

The symbols ×, ○, and △ in the table indicate the following conditions, respectively.

×: Do not destroy the turtle.・ ○°I broke one wave of Houki.

△: Edge discharge occurs, but it does not reach due to destructive power.

■ Ferroelectric crystallized glass film thickness: 1011 m ■ Ferroelectric crystallized glass film thickness: 20 μm (3 Ferroelectric crystallized glass film thickness: 30 μm These experiments were conducted using the circuit shown in Figure 6. .

In this circuit, when the input of the AC low source 11 is 200V150Hz, the output 4N+1 of the choke coil 6 is 20V.
A high voltage pulse voltage with a peak value of tJ f) ~2600V is generated. 2 is a ceramic capacitor, 4 is a diode, 12 is a resistor, :l;j SSS wire.

Next, the relationship between the diameter of the coated surface of the 'S film electrode of this ceramic substrate and the peak value of the high voltage pulse voltage was measured, and the result was as shown in FIG. If the diameter of the silver film electrode is smaller than 24 mm, the circumference of the electrode is 1 or more and the periphery of the ceramic substrate is 1b.
Since the pulse voltage decreases when the distance d of 1 exceeds 1.0 mm, it is disadvantageous to make the non-bonded part of the electrode thick in order to generate the high voltage pulse that will reliably light the lamp. Become. - hence the non-contact distance between said peripheral edges *I ij 1.2 mm'! What should I do?
L.

In addition, the thickness t of the coating film of strong '6 body crystal glass is 30 μn.
When the time exceeds t, the ceramic capacitor cannot be destroyed at the stage when the light emission 'g1 starts to slow down.
When the gas pressure is on the order of 1o-3 to 10-2 torr, the current flowing through the ballast 1o is 1.2 to 1.4 times the normal value, and if this time becomes longer, an overcurrent will flow to the ballast winding. Otherwise, the windings may be burnt out. Therefore, it is desirable that the thickness of the coating film of ferroelectric crystallized glass be 10 to 20 μm.

The present invention was actually implemented using a high-pressure thorium lamp with a rated human power of 360W. The content of the luminescent chamber was 5.1 cc, into which xenon scum was sealed together with appropriate amounts of mercury and sodium at a pressure of 150 Lorr. Since the outer sphere is 1000 cc, all of the xenon scum from the luminescent station 1 leaked into the outer sphere 5, resulting in a pressure of 0.8 Ir.

This outer sphere has a structure as shown in FIG. When a single dielectric ceramic capacitor was housed and a high pulse voltage was generated, the ferroelectric ceramic capacitor was successfully destroyed by the xenon scum that leaked from the seal of luminometer 1 at the end of the lamp's life.

Effects of the Invention As is clear from the above explanation, according to the present invention, by appropriately selecting the structure and dimensions of the ferroelectric raw ceramic capacitor constituting the starting device, the high voltage pulse voltage at the end of the lamp life can be reduced. It is possible to effectively prevent damage to the glass bulb and burnout of the ballast due to application.

[Brief explanation of the drawing]

1 and 2 are circuit diagrams of a high-pressure tortoise lamp embodying the present invention, FIG. 3 is a detailed groove diagram of the same lamp, and FIG.
The figure is a pressure-charge characteristic diagram of the ferroelectric ceramic capacitor used in the present invention, and Figure 5 is the pressure-charge characteristic diagram of the ferroelectric ceramic capacitor used in the present invention.
Fig. 6 is a cross-sectional view of a raw ceramic capacitor, Fig. 6 is a suction circuit of the same capacitor, and Fig. 7 is a diagram showing the relationship between the ceramic base and the circumference of the capacitor, the gap distance, and the peak value of the high-voltage pulse voltage. In Fig. 1 and Fig. 5, 1. Light emitting station, 2.. Extortion itn ceramic capacitor, 5.. Outer sphere, 7.
Ceramic substrate, 8a, 8b... silver film low 1 blood, 9...
・Ferroelectric 1 raw crystallized glass. Figure 4 Figure 6 Figure 7 (V) 0 04 0.8 1.2 (mm)

Claims (1)

[Claims] Distance Al1 between the periphery of the ceramic substrate 7 and the periphery of the conductive membrane electrode (8a, sb) provided on the ceramic broken end plate 7
A ferroelectric ceramic capacitor 2 in which d is selected to be O to 1.2 am, and the entire outer periphery of the ceramic substrate 7 and electrodes 8a and 8b is completely overcoated with ferroelectric crystallized glass 9 except for the lead terminal portions. This is a high-pressure discharge lamp in which the lamp is housed inside an outer bulb 5.