JPS599847A - Small size metal halide lamp - Google Patents

Abstract

PURPOSE:To make a lamp possible to start with a starting voltage of less than 2,000V and its glow start-up performable smoothly and surely as well as dielectric breakdown preventable, by starting the lamp with the vaporization density of mercury raised up in advance so as to cause a pressure ratio between argon and mercury to produce an optimum penning effect. CONSTITUTION:A ratio of vaporization density in mercury to argon sealing partial pressure is adjusted so as to be more than 5X10<-5> but less than 3X10<-3>, and in time of starting, the mercury is vaporized by a preheating heater. Temperature inside a glow tube 2 rises and if the temperature reaches somewhere around 60 deg.C by way of example, the starting voltage comes below 2,000V so that when the pulse voltage produced by a glow starter 20 is impressed, the glow tube 2 starts glowing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a small metal halide lung having an operating power of 100 watts or less, and to improving the starting characteristics thereof.

[Technical background of the invention and its problems]

In recent years, progress has been made in the development of small metal-ride lamps that can replace general incandescent light bulbs as an energy-saving light source. Metal halide lamps have high efficiency and high color rendering properties, so they can save money if used in place of general incandescent light bulbs. It has a big effect on electricity.

To replace metal halide lamps with incandescent bulbs,
It is necessary to reduce the power during rated operation to 100 watts or less, and metal halide lamps in the 20 to 50 watt class have recently been researched and developed. In such a small metal halide lamp, the internal volume of the arc tube is small, and the distance t between the main electrodes is extremely small, on the order of 2 to 10 degrees.

In this type of small metal halide lung of 100 watt class or less, a gas containing argon as a main component is used as the starting rare gas sealed in the arc tube. The reason for using argon is to facilitate starting due to the Penning effect with mercury. In addition to argon, helium and neon are known to exhibit the Penning effect with mercury, but helium and neon have high thermal conductivity, so they reduce luminous efficiency, and they also It is not recommended to use it because it has the property of easily transmitting helium and neon, and there is a problem that helium and neon will disappear with long-term use.

When using a gas whose main component is argon as the starting rare gas, conventionally, in large metal halide lamps, it is used at a sealing pressure of 10-odd Torr to less than 50 Torr; In small metal halide lamps, the electrodes are small and the distance between the electrodes is short, so when trying to form a cathode bright spot, the electron impact is relatively large, and the electrodes are severely worn out due to growth 4-driving, resulting in early blackening. This also causes a decrease in luminous flux maintenance rate. In order to prevent this, argon is sealed at a pressure of 50 Torr or higher at room temperature (15° C.), specifically at a high pressure such as 1 20 Torr.

However, if argon is filled in at high pressure, there is a problem in that startability deteriorates. In particular, this type of small metal Ride Lang has a small arc tube, so it is not possible to attach an auxiliary electrode for startup, and the argon sealing pressure is high, so the ratio to the mercury vapor density at startup is low. This is due to the fact that the partial pressure ratio (ratio of mercury vapor density to argon pressure) that produces the optimal 4-ning effect is not reached, and the starting voltage is required to be 2000 V or more.
It is easy to cause dielectric breakdown.

There is a problem.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and its purpose is to raise the density of mercury vapor and start it up so that the pressure ratio between argon and mercury produces the optimum Penning effect. The object of the present invention is to provide a small metal ride rung that can be started with a starting voltage lower than the initial voltage, can be started smoothly and reliably, and does not cause dielectric breakdown.

[Summary of the invention]

In the present invention, argon and mercury have a starting voltage of 2000? The ratio of the mercury vapor density to the argon fill partial pressure that produces an optimal inning effect below 5 x ] 0-
It has been confirmed through experiments that mercury is less than or equal to 5 and less than 3.times.10@-3, and the mercury is evaporated by a preheating heater so as to produce the above pressure ratio at the time of startup.

[Embodiments of the invention]

An embodiment of the present invention will be described below based on the drawings.

In the figure, 1 is an outer tube, and within this outer tube 1 is housed an arc tube 2 made of quartz glass.

The arc tube 2 is formed into a spherical shape, for example, and has an internal volume as small as that of an ICC. Inside the arc tube 2 is a main electrode 3.
4 is hermetically sealed, and these main electrodes 3, 4 are connected to a molybdenum foil 5.6 within the sealing part. The distance t between the main electrodes 3 and 4 is set to 2 trrrn to 10 mm.

The arc tube 2 is filled with a predetermined amount of mercury, a metal rhodanide such as scandium sodium iodide, and argon gas at a pressure of l 20 Torr at room temperature of 15°C. The molybdenum foil 5.6 is connected to external lead wires 7 and 8, and one of the external lead wires 7 is connected to one of the wells 1 stuck to the stem 10 via a support frame 9. , the other external lead wire 8 is connected to the stem 1
The well 12 is connected to the other well 12 which is sealed to the other well 12 .

The wells 11 and 12 are the caps 1 attached to the ends of the outer tube 1.
3 and central terminal 14.

Reference numeral 15 designates a filament coil as a preheater, one end of which is connected to the other well 12 via a lead wire 16, and the other end is connected to a bimetal switch 17. Nonoi metal switch 17 is insulator 1
8 , which insulator 18 is fixed to the well 11 by support wires 19 . The bimetal switch 17 is connected to one well 1 via a lighting tube 20. Therefore, the filament coil 15, the bimetallic switch 17, and the lighting tube 20 constitute an electrical series circuit as shown in FIG. has been done. The filament coil 15 is provided close to the arc tube 2, and is placed in such a position that the arc tube 2 is heated when the filament coil 15 generates heat. The bimetal switch 17 is closed at room temperature and is set to open when the ambient temperature reaches, for example, 70° C. or higher.

Note that 2 indicates a getter, and 22 indicates a stabilizer.

In the small metal halide lamp having such a configuration, when voltage is applied through the ballast 22, current flows through the filament coil 15 and the lighting tube 20 because the bimetal switch 17 is closed. The lighting tube 20 repeatedly blinks, and while the contacts are closed, the filament coil 15 becomes red hot, emits light heat, and heats the arc tube 2. The arc tube 2 evaporates mercury by being heated, and the ratio of the mercury vapor density to the argon gas pressure approaches a range where the Penning effect can be exerted, thereby lowering the starting voltage.

During this time, the lighting tube 20 continues to supply current to the filament coil 15, generating a voltage of 1,000 ls each time it blinks, and the pulse peak value is approximately 2,000 ls. It is Nruto. When the temperature inside the arc tube 2 rises and reaches around 60°C, for example, the starting voltage becomes 2000 volts or less, so when the voltage generated by the lighting tube 20 is applied, the arc tube 2 starts. do.

When the arc tube 2 starts, the outer tube 1 is heated due to the heat generated by the arc tube itself.
When the temperature inside rises, for example exceeding 70° C., the bimetal switch 17 is opened. Therefore, the filament coil 15 is no longer energized, and the filament coil 1
5 red heat is stopped.

In such a configuration, the filament coil 15 emits light after the power supply voltage is turned on until the arc tube 2 starts, so brightness can be obtained from the light emission of the filament coil 5 ( After the arc tube 2 is activated, brightness is obtained by the light emitted from the arc tube 2. Therefore, illumination light can be obtained immediately after the power is turned on.

However, the small Metalno Ride Lang mentioned above is 2000
The reason why it can be started at a voltage lower than , W rut is as follows.

First, the vapor pressure of mercury changes depending on the ambient temperature, and the rate of change is as shown in Table 1 below.

Table 1 On the other hand, Figure 3 shows the mercury vapor density (=mercury vapor pressure) PH and the case where the product (pAxz) of the main electrode distance L (cm) and the Alkon gas pressure PA (Torr) has various values. FIG. 3 is a relationship diagram in which the starting voltage Vll ('root) is investigated when the ratio PH/PA of the argon filling pressure PA is changed. It is known that the starting voltage depends on the product of the distance t between the electrodes and the gas pressure of the sealed gas, for example, from ``Discharge...Ndozok'' (edited by the Institute of Electrical Engineers of Japan, published by Ohm Publishing, p. 99, 1972). That's true. From Figure 3 above, the range in which the mercury and alco-9ne effects are particularly pronounced is as follows:
It is observed that P, is approximately 2×10−′ times as large as PA.

For example, the distance t between the electrodes is] Ortrm (= 1 c
In the lamp in which the argon filling pressure PA is 120 Torr, the mercury vapor pressure PH is 7.7 X l O-' Torr from Table 1 at a room temperature of 15°C, so P) I/PA = 6. 4X ] O-6, which is outside the range where the Penning effect can be effectively exerted, and requires a high starting voltage of 2100 to 2200°.

Therefore, with such a lamp, the value of PH/PA is 2
To make l O-', the mercury vapor pressure PH should be 2.4x10
-2 Torr, that is, the ambient temperature can be raised to about 60'C according to Table 1. As can be seen from FIG. 3, if the ambient temperature is preheated to about 60° C., starting can be achieved even with a starting voltage of about 500 delts.

In addition, in the case of paxz=]20 Torr-cm, 2
000? It can be seen that in order to start with a starting voltage of □ below the normal temperature, it is sufficient to heat the arc tube to about 20° C. or higher.

The argon sealed in the arc tube is 50 Torr or more6
00 Torr or less. That is, 5 Q T
As already mentioned, the electrodes are small and the distance between them is small, so the snow'? The electrodes are more likely to break or blacken due to vines, shortening their lifespan.

Moreover, if the temperature exceeds 600 Torr, the following problems will occur. In other words, the average temperature inside the arc tube during lighting operation is 100
It reaches temperatures of 0 to 2,000 degrees Celsius, and the pressure inside the arc tube reaches around 30 atmospheres just from the evaporated mercury.
At 1,500° C., the pressure of alkon gas at 0.00 Torr becomes about 6 times, or about 5 atm. Efforts have been made to ensure that the pressure resistance of the arc tube is sufficiently high by adopting a spherical shape, but it is limited to about 70 atmospheres at room temperature.

Therefore, even if the safety factor is assumed to be 0.5, it is necessary to keep the total pressure inside the arc tube below about 35 atmospheres, and it is desirable that the alcohol gas pressure during lamp operation be about 5 atmospheres at most.

Also, at 15°C, the argon gas pressure PA is 600 T.
orr, to achieve the optimal penning effect, P
H/P = 2X] 0-' to mercury vapor pressure P, is] 2X
Approximately 10-2 Torr is required. This requires an ambient temperature of approximately 90° C. according to Table 1. At such an ambient temperature, the encapsulated metals with high vapor pressure, such as tin iodide, or the metals produced by the reaction between the encapsulated metals and the arc tube material. - Silicon rodenide or mercury chloride evaporates and begins to act as an impure gas, increasing the starting voltage. Therefore, it becomes undesirable to make the ambient temperature too high, so the optimum mercury temperature cannot be made high, and the argon filling pressure is regulated at this point. The upper limit is about 600 Torr.

Fax when the argon sealing pressure PA is 600 Torr and the distance t between the electrodes is l Om (1 cm), which is the worst condition. =600 Torr-on, but in this case, 2000. As shown in FIG. 3, the range in which the device can be activated with a voltage below volts is P k/P, which is in the range of 5×10 2 to 3×10 2 .

Incidentally, Table 2 shows the results of tests conducted under various conditions.

As can be seen from Table 2 above, Pit/PA is 5X10-
If the arc tube is preheated to a range of 5 to 3 x 10, it will be 2000. It is possible to start the engine with a starting voltage below y.

Note that 100% argon gas is preferable as the starting rare gas, but helium/neon may be mixed with argon. In this case, in order to maintain the Penning effect of argon and mercury, it is necessary to enclose at least 70 parts of argon, which means that argon is the main component.

However, the present invention is not necessarily limited to providing the lighting tube 20, and as can be seen from FIG.
A starter tube is not required if the engine can be started even if the engine is at a low level.

Further, the arc tube is not limited to one made of quartz glass, but may be made of a translucent ceramic tube such as alumina Chewy.

〔Effect of the invention〕

According to the present invention as described in detail above, by heating the arc tube with a preheating heater when starting the arc tube, the ratio of the mercury vapor density to the partial pressure of argon sealed in the arc tube is 5 x 10 to 3 x 10. 20
00.1? Starting is possible even with a starting voltage lower than the default.

Therefore, starting is performed easily and reliably, and the starting voltage is lowered, which has the advantage of preventing problems such as dielectric breakdown.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a block diagram of a small metal halide lamp, FIG. 2 is a circuit diagram thereof, and FIG. 3 is a characteristic diagram. No... Outer tube, 2... Arc tube, 3, 4... Main electrode,
15... filament coil (preheater), 17.
...／? Imetal switch, 2o...lighting tube.

Claims (2)

[Claims] (1) A rare starting gas containing mercury, a metal halide, and argon as main components is sealed in an arc tube in which a pair of main electrodes are hermetically sealed, and the partial pressure of the filled gas at 15°C is set to 50 Torr or more. operating power 100
In a small metal halide lamp of watt class or less, a preheating heater that preheats the arc tube such that the ratio of the vaporized vapor density of mercury to the partial pressure of argon is 5 x 10 or more and 3 x 10 or less when the arc tube is started. A small metal ride lung characterized by the addition of. (2) The small metal halide lamp according to claim 1, wherein the preheating heater is a filament coil, and the filament coil emits visible light during preheating operation.