JPS6349340B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a low pressure mercury lamp device.

Conventional low-pressure mercury lamp devices are used for fluorescent lamps, germicidal lamps, photochemical reactions, etc., and the lamp current is usually around 0.4A. And even what is said to be an ultra-high output type is only about 2A. By the way, if the lamp current is increased to 2A or more, the lamp power per unit length of the light emitting part increases, which makes it possible to relatively miniaturize the device and increase the radiation spectral density, thereby increasing the yield of the photoreaction. We can expect the possibility of increasing the sterilization capacity and the amount of sterilization per unit time. For this reason, in industrial applications, a low-pressure mercury lamp device that can provide a large lamp current without increasing the size of the device is desired. However, in conventional low-pressure mercury lamp devices, when a large alternating current is applied to the electrode, the electrode temperature rises due to electron bombardment when the electrode is in anode mode, causing consumption of the electron radioactive material (commonly known as emitter) coated on the electrode. This is severe, causing blackening of the bulb and poor lighting, resulting in a shortened lifespan. In order to prevent this, conventionally an auxiliary anode has been installed to alleviate the electron impact, but even so, it has no mitigation effect when the lamp current exceeds about 2A, and conventional low-pressure mercury lamp devices can maintain a small size and long life. However, there was no industrial low-pressure mercury lamp device that could carry a large current of 2A or more.

Therefore, an object of the present invention is to provide a low-pressure mercury lamp device that can flow a large current while maintaining a small size and long life. 2 in the valve
In each "electrode assembly," the anode is connected to the cathode without intervening a semiconductor rectifying element, and the anode is arranged in front of the cathode and in the radial direction of the bulb. It has a cross-sectional area of 80% or less of the area, 5% or more, and a length of 5 mm or more in the axial direction of the bulb, and the bulb contains at least 1 mmHg or less of mercury at a pressure during lighting. This is characterized in that the anodes and cathodes belonging to different sets discharge each other, and this is repeated alternately to sustain the discharge.

The present invention will be specifically described below with reference to the drawings.

FIG. 1 is an explanatory diagram of a low-pressure mercury lamp device including the features of the present invention, in which 1a and 2a are a directly heated hot cathode and anode, respectively, belonging to the first set, and 1b and 2b are respectively belonging to the second set. A directly heated hot cathode and an anode, in which the anode is connected to one side of the cathode in each pair. The anode of each set is arranged in front of the cathode, and the size of the anode is such that the shielding rate (the ratio of cross-sectional area expressed in %) in the radial direction of the bulb 6 is 5 to 80%, and The length in the direction is 5 mm or more. This pair of anode and cathode is sealed to both ends 6a and 6b of the bulb 6, respectively. The inside of the bulb 6 is filled with a trace amount of mercury or a rare gas such as mercury and argon.
Reference numeral 4 indicates a current limiting current limiting coil; 5 indicates a transformer; secondary windings 5a and 5b are used as power sources for directly heated hot cathodes 1a and 1b belonging to the first and second sets, respectively; are connected to the anodes 2a and 2b belonging to each set, so as to provide discharge light emission. The primary winding 5d is a commercial power source, e.g.
Connected to 100V or 200V power supply 7.

In the above-mentioned low-pressure mercury lamp device, discharge formation is performed as follows.

In the first AC half cycle, the current flows as shown by arrow 8, and in the next AC half cycle, the current flows as shown by arrow 9.
Current flows as shown in . This is repeated alternately to sustain the discharge. Note that the direction of the current is opposite to the flow of electrons.

That is, a discharge is formed by pairs of anodes and cathodes belonging to different sets alternately passing through the same discharge medium.

The basic advantages of the above low pressure mercury lamp device are listed below.

(1) Since the anode and cathode have different design concepts, in the case of the present invention, the anode can be designed only based on the design concept of the anode, and the cathode can be designed only based on the design concept of the cathode. , a large current, low pressure mercury lamp device can be provided. In addition, it becomes easier to design an electrode with a long service life and a low discharge starting voltage.

(2) When a metal vapor discharge lamp with a long arc length is designed as a conventional DC discharge lamp, the metal ions are biased toward the cathode side, causing uneven light emission. Defects are eliminated.

The above advantages can be better understood by looking at the following design example.

The bulb is made of ozone-free quartz with an inner diameter of 10 mm, the arc length is 300 mm, and the discharge medium is mercury and 0.3 mmHg of argon gas, which has a vapor pressure of 6 x 10 ^-3 mmHg during discharge light emission. In this case, the voltage of the low-pressure mercury lamp was approximately 59V, the current was 4A, and the power consumption was approximately 200W. As a cathode, a tungsten filament (BaSrCa) is used.
The design is coated with BeO ₂ (barium strontium calcium ternary berylate) to achieve the best electron emissivity, and the anode is made of tungsten rod to withstand the impact of large electron currents, with the basic concept of durability. I am designing. Therefore, the above-mentioned low-pressure mercury lamp device is not only smaller in length to about one-sixth of the conventional size, but also has a significantly larger current value, and as a result, ultraviolet radiation is significantly reduced. It can be increased.

In a low-pressure mercury lamp, if the current value is increased,
Although it is known that ultraviolet radiation is increased, a compact, long-life, low-pressure mercury lamp device cannot be obtained using conventional design concepts. This is clear when considering that the current values of currently commercially available fluorescent lamps, low-pressure mercury lamps, and germicidal lamps are all less than 2A.

If we compare the conventional germicidal lamp of about 200W and the low-pressure mercury lamp device described above in terms of the amount of radiation from an arc length of 2537 Å per cm, the radiation intensity of the present invention is several tens of times higher. , the productivity when used for industrial purposes is incomparably high.

As can be understood from the above design example of a low-pressure mercury lamp device, (3) A small, long-life low-pressure mercury lamp device that can be used with a current value of about several tens of amperes can be easily obtained and can be combined with other conventional technologies. (4) If quartz glass, which transmits 1849 Å well, is used as the material for the bulb, a low-pressure mercury lamp device for powerful ozone generation can be obtained.

(5) If you choose ozone-free quartz glass or hard glass for germicidal lamps as the material for the bulb, you can obtain a powerful sterilizing device that does not generate ozone.

There are advantages to saying that.

Quartz glass, ozone-free quartz glass, and germicidal lamp glass are all commercially available, and their spectral transmittance characteristics are described, for example, in Toshiba Review (Vol. 34, No. 5, p. 448).
Glass Engineering Handbook, page 670 (Asakura Shoten Showa)
(10th edition published June 20, 1948). In addition to the above-mentioned materials, translucent ceramic tubes such as polycrystalline alumina (trade name Lucarox) can also be used.

The mercury vapor pressure during discharge light emission can be determined by the amount of mercury filled in when manufacturing the discharge lamp, or by providing a mercury stopper in the bulb and keeping the temperature of the mercury stopper at a predetermined constant value. You can achieve it,
Moreover, an indirectly heated type may be used as the hot cathode.
Known methods can be used for all of these. Furthermore, a fluorescent lamp may be constructed by coating the inner or outer surface of the bulb 6 with a fluorescent substance to obtain strong light emission.

By the way, in the low-pressure mercury lamp device of the above design example, for practical use, the anode and cathode in each set have different design concepts as described above, so the current flow must completely flow between the anode and the cathode every half cycle of AC. It must be made to flow into the cathode.
And it highly depends on the position, shape and dimensions of each electrode. Taking the first set of electrodes as an example, during a half cycle in which the first set of electrodes is at a positive potential with respect to the second set of electrodes, the current must flow completely from the anode. Current flowing out of the cathode means that there is an electron bombardment on the cathode, and when the lamp current is as large as in the lamp of the present invention, the temperature of the cathode becomes very high. And emitters such as (BaSrCa)BeO ₂ cause rapid evaporation, significantly shortening the life of the electrode.

In order to prevent the above-mentioned problem, there is a method of connecting the cathode of the semiconductor rectifying element to the anode and the anode to the cathode at the connection positions 3a and 3b (Japanese Unexamined Patent Application Publication No. 1983-1996-1).
160755 Inventor Arakawa et al.) However, the present invention attempts to obtain the same effect by specifying the position and size of the anode without using the semiconductor rectifying element. As a result of various experiments, it was found that the following conditions are necessary for the current to flow completely from the anode when the electrode is in the anode mode.

(1) The anode must be placed before the cathode. This is because both the anode and the cathode are connected at the connection position 3a, so they have the same potential, and the electrons moving from the front of the discharge path flow into the nearest electrode.

(2) The anode must have a certain size or more. In each electrode set, no current flows from the cathode when in anode mode. In other words, in order to prevent electrons from flowing in, the anode needs to have a certain size or more. In Figures 1 and 2, the shielding rate for the discharge path by the anode in the radial cross section of the bulb, ie,
(d/D) ² is 0.8 (80%) or less, 0.05 (5%) or more, and the length l in the axial direction of the anode discharge path is 5
mm or more is required. Tungsten, which has high electron impact resistance, is usually used for the anode. (d/D) ² is 0.8
Exceeding this will greatly narrow down the discharge path in the cathode mode, increasing the discharge resistance and impairing lighting performance. Conversely, (d/D) ² is 0.05
If it is less than 100%, when in the anode mode, all the electrons do not flow into the anode but also into the cathode, which causes the cathode to be bombarded with electrons, causing significant wear and tear on the cathode and shortening the life of the cathode. Also, in the discharge state,
The anode has a length 1 in the axial direction of the discharge path, but if this length is not sufficient, electrons will reach the cathode due to so-called "seep" of electrons. In other words, if the lamp current in a half cycle of an AC discharge is Il, the current flowing from the anode is Ia, and the current flowing from the cathode is Ic, then Il = Ia + Ic, so in anode mode Il = Ia and in cathode mode Il = It would be good if it became IC. In anode mode, when electrons ``seep'', Ic≠0 and Ic/Il becomes a certain ratio. To explain this specifically, for example, bulb diameter D = 10 mm, anode diameter d = 3.6 mm, arc length 300 mm, and vapor pressure during discharge light emission as a discharge medium is 6 × 10 ^-3 mmHg.
Fill with 0.3mmHg of mercury and argon gas. When the shielding rate of the anode was 13% and the lamp current was 5 A, Ic/Il was measured while changing the axial length l of the discharge path of the anode, and the result was as shown in Fig. 3. Even when the lamp current was changed from 2 to 20 A, the ratio of Ic/Il at each l did not change much. That is, when (d/D) ² is 0.8 or less and 0.05 or more, if l is 5 mm or more, no current will flow from the cathode when the electrode is in the anode mode due to "bleeding" of electrons. Therefore, each electrode is used based on its design concept, and a large current, low pressure mercury lamp device can be provided. When in cathode mode, electrons are not normally emitted from the anode because the work functions of the constituent materials are very different between an anode made of tungsten and a cathode coated with (BaSrCa)BeO ₂ , for example.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the main parts of the low-pressure mercury lamp device of the present invention, FIG. 2 is a sectional view taken along the line shown in FIG. 1, and FIG. 3 is an explanatory diagram of data. 1a, 1b...cathode, 2a, 2b...anode, 4...chiyoke coil, 5...transformer, 6...valve.

Claims (1)

[Claims] 1. Two sets of "electrode sets" consisting of an anode and a cathode are provided in the bulb, and in each "electrode set", the anode is connected to the cathode without intervening a semiconductor rectifying element. The anode is located in front of the cathode, has a cross-sectional area of 80% or less and 5% or more of the bulb cross-sectional area in the radial direction of the bulb, and has a cross-sectional area of 5 mm or more in the axial direction of the bulb. It has a length, and the inside of the bulb has at least a pressure of 1
A low-pressure mercury lamp device containing mercury of less than mmHg and characterized in that an anode and a cathode belonging to different sets discharge each other, and this is repeated alternately to sustain the discharge.