JPS5842586B2 - flash discharge lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flash discharge lamp suitable for use in, for example, photographic strobes and flash devices.

Conventionally, various metals, including alkaline earth metals, have been used in various forms as electron-emissive substances for the cathodes of flash discharge lamps.

Since the cathodes of these discharge lamps have advantages and disadvantages in terms of collapse, they are usually selected and used depending on their light emitting output or purpose.

In general, the lower the starting voltage for a discharge lamp to emit light, the better it is. Since there are many things that must be done, and the voltage cannot be set very high, the characteristics described above are strongly desired.

On the other hand, recently there has been a strong demand for compact, high-output, long-life flash discharge lamps, and research into flash discharge lamps using sintered cathodes,
Development is progressing.

However, in the case of conventional flash discharge lamps using sintered cathodes, although they have the advantage of good input resistance characteristics and long lifespans, on the other hand, the starting voltage decreases in the initial stage when the number of times of light emission is small. It has a rather high disadvantage.

By the way, as is well known, cesium has good secondary electron emissivity and is used, for example, as a cathode material in phototubes. Depending on the conditions, cesium also has good thermionic emission properties, so it has been used in discharge lamps since ancient times. It is considered to be used as a cathode material.

However, cesium is a substance that is difficult to handle as a cathode material for discharge lamps due to its chemical and physical stability and vapor pressure characteristics. Furthermore, since it has low resistance to temperature, it is not suitable for discharge lamps where the electrode temperature rises significantly, such as high-pressure mercury lamps and xenon short arc lamps.

However, the market demand for flash lamps with large luminous materials and low operating voltages is stronger than ever before, and the present invention was made from this point of view. This is one of the research results.

An object of the present invention is to provide a flash discharge lamp equipped with a sintered cathode having a low operating voltage, particularly one in which sputtering phenomenon is suppressed. The sintered cathode is constructed by containing 0.1 to 4% by weight of cesium oxide.

As mentioned above, cesium or cesium compounds have drawbacks that make them difficult to handle, but they are
46355 (Co-invented by Akira Morita and Harumi Handa), patent application 1977
9-80215 (Invented by Kensaku Moriya) Jitsugan Showa 5O-8905
5 (co-invented by Yasuo Onishi and Harumi Handa), and has reached the stage of practical use, since the sputtering phenomenon during use of a discharge lamp is significant, this point is particularly taken into consideration in the present application.

Examples will be described below.

Example 1 For a flash discharge lamp with a bulb diameter of 3.2 mm, a distance between cathodes and anodes of 20 mm, and a xenon gas pressure of 50011 LrILHg, the initial operating voltage is 200 V when a barium-based (cesium-free) sintered cathode is used. So it's 170V, which is 30V lower.

If this cesium system can be operated at the conventional 200 mm, on the other hand, the gas pressure can be increased to about 100 mm) (g), and in that case, the amount of light emitted can be increased by 10%.

Example 2 A comparison similar to the above was made for a flash discharge lamp with a bulb diameter of 4.011tTL%, a cathode-anode distance of 40 mm, and a xenon gas pressure of 280 mmHg.
If the operating voltage is the same with a lower gas pressure of about 100 mmH, 9 extra filling, the amount of light emitted will increase by 25%.

Example 3 Valve diameter 10 mm, distance between cathode and anode 200 mB, xenon gas pressure 120 m1H,! In a li+ flash discharge lamp, the cesium-based lamp is 150 mm lower, and if the gas pressure is increased by about 80 mmH9 and the operating voltage is kept the same, a 60% increase in light emission can be obtained.

The following is understood from the above embodiments.

(b) If you use a cesium-based sintered cathode, you can choose between a low operating voltage or a high luminescence amount, and if you choose an intermediate value, you will be able to achieve better results than conventional products. A device with a low operating voltage and a large amount of light emission can be obtained.

(b) The technical effect described in item (a) above is greater as the flash discharge lamp becomes larger.

The data in Figure 1 is one of the experimental data showing the above, and for a flash discharge lamp with a xenon gas pressure of 500mlH, 9, the horizontal axis represents the cathode-anode distance, and the vertical axis represents the operating voltage.
The parameters are shown for non-cesium type (Curve A) and cesium type (Curve B).The larger the distance between the cathode and the anode, the larger the expected voltage drop, and if necessary, the larger the amount of light emitted. can be expected.

By the way, the cesium type mentioned above has a greater sputtering phenomenon during use than the barium type, and this tendency increases as the flash discharge lamp becomes larger, canceling out the merits mentioned above. Alternatively, the content of cesium compounds was specified.

The data in Figure 2 shows the weight percentage of cesium oxide relative to the base metal on the horizontal axis, the number of ignitions on the vertical axis, and the target life of 30.
This is one of the data that investigated the sputtering phenomenon at 00 times 1, and as can be understood from the figure, the target life is 80
% or more, the content is preferably 01 to 4.0%.

If the content is less than 0.1%, it is undesirable because the electron-emitting radioactive substance is insufficient and is quickly consumed, resulting in an increase in operating voltage and sputtering of the base metal due to difficulty in ignition.

If the content exceeds 4.0%, the sputtering phenomenon will become significant at about 80% of the target life or less, which is undesirable.In the end, by setting the content to 01 to 460%, the above-mentioned merits can be offset. It is possible to provide a flash discharge lamp with good quality without any problems.

As detailed above, the present invention has the advantage of providing a flash discharge lamp with a sintered cathode that has a low operating voltage, particularly one that suppresses sputtering phenomena.

As mentioned above, cesium-based materials have the drawback of low physical and chemical stability, so base metals such as di, zirconium,
By adding a getter agent such as tantalum, titanium, or magnesium to absorb impurity gas generated within the bulb during use of the discharge lamp, the flash discharge lamp of the present invention can be provided with even more stable performance.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of experimental data on voltage drop, and FIG. 2 is an explanatory diagram of experimental data on life.

Claims (1)

[Claims] 1. In addition to the base metal, cesium or a cesium compound may be added to the base metal in an amount of 0.0% in terms of cesium oxide.
A flash discharge lamp comprising a sintered cathode containing 1 to 4% by weight. 2 The sintered cathode is made of zirconium, tantalum, titanium,
2. The flash discharge lamp according to claim 1, wherein a getter agent such as magnesium is added.