JPH03114200A - Starter device for metal halide lamp - Google Patents

Abstract

PURPOSE:To provide a metal halide lamp starter device with which resumption of the lamp can be made certainly, by furnishing a thermo-response switch which uses a W coil to one side of the contact to shortcircuit a main electrode with a start assist electrode, and thereby preventing premature degradation of a non-linear capacitor (FEC). CONSTITUTION:A bi-metal 232 fixed to a COM contact 230c is mounted on a thermo-response switch board 252. This bi-metal 232 has contacts 234, 236 on both contact sides of an NC contact 230a and a NO contact 230b. A W coil 250 is mounted to the NC contact 230b. When this lamp concerned is started, the thermo-response switch separates at approx. 80 deg.C from the NC contact 132a, and touches the NO contact 130b at aprox. 200 deg.C. When the lamp is extinguished (resume), the thermo-response switch separates at approx. 200 deg.C from the NO contact 130a and touches the NC contact 130b at approx. 80 deg.C. Between 200 and 450 deg.C the W coil deforms, and no stress is applied the bi-metal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a metal halide lamp starting device and its switch.

Particularly [Prior Art] Metal halide lamps have a spectrum covering the entire visible range, excellent color rendering properties, and good luminous efficiency, so they are widely used in the field of lighting for sports, commercial facilities, and the like.

By the way, since it is generally difficult to start this metal halide lamp by applying a power supply voltage to it, a starting device having a configuration as shown in FIG. 5 has conventionally been incorporated into the lamp.

First, the starting device shown in FIG. 5 includes a thermally responsive switch 12 and a nonlinear capacitor (hereinafter referred to as FEC) 14 connected in series with the switch 12.

Further, an arc tube 16 is connected in parallel to the series circuit of the thermally responsive switch 12 and the FECI 4.

Since the starting device according to the illustrated example is roughly configured as described above, when voltage is applied to the starting device via the choke coil 18 while the arc tube 16 is off, the starting device is activated via the thermally responsive switch 12. A voltage is applied to the starting circuit of FECI4. With respect to this applied voltage, the non-linear capacitance change causes a change in the switching current of the circuit, and ■
A pulse voltage expressed as , =-L di/dt is generated,
The lamp starts (Special Publication No. 48-28726).

Further, FIG. 6 shows a circuit in which a starting resistor 20 and a starting auxiliary electrode 22 are provided inside the arc tube 16 in the circuit shown in FIG. The starting auxiliary electrode 22 allows the main electrodes 24a and 24b of the arc tube 16 to
During this period, discharge is more likely to occur than in the case of the circuit shown in FIG. 5, and due to the pulse oscillation by the FEC 14, discharge is started between the bipolar electrodes 24a and 24b, and the arc tube 16 is lit.

Then, while the lamp is on (when stable), the thermal response switch 1
The switch 12 is turned off by being heated by the radiant heat from the arc tube. As a result, FEC
The oscillation of 14 is also stopped.

In addition to this, a starting device as shown in FIG. 7 has been developed.

The starting device shown in the figure is provided with an auxiliary electrode side thermally responsive switch 26 that corresponds to the starting resistor 20, separately from an FEC side thermally responsive switch 12 that corresponds to the FEC 14.

[Problems to be Solved by the Invention] However, the starting device shown in FIG. 6 has the following drawbacks when the lamp is lit for a long time.

That is, during lamp lighting (when stable), main electrode 24a - arc discharge column - starting auxiliary electrode 22 - starting resistor 2O - FEC
The voltage shown in FIG. 8 continues to be applied to the FEC 14 via the circuit consisting of 14.

Generally, the holding temperature of FEC14 during lamp operation is approximately 300°C when installed near the neck of the lamp;
FEC 14 becomes higher than the Curie temperature of FEC 14 (approximately 90° C. in this case), and FEC 14 becomes a paraelectric material, and its dielectric constant decreases and its capacitance also decreases. Therefore, since the impedance becomes high, the voltage between the terminals of the FEC 14 also becomes high as shown in FIG.

As described above, when a high voltage is applied for a long time in a high temperature state, the silver in the silver film electrode of FEC14 diffuses (migrate) along the grain boundaries, and as a result, FEC1
4 is deteriorated, leading to a decrease in the Norculus voltage. According to experiments, when attached to a 400W lamp, approximately 10
It has been found that after 00 to 2,000 hours of lighting, a phenomenon occurs in which self-destruction occurs due to the generated pulses due to deterioration of the insulation resistance of the FEC.

On the other hand, in the starting device shown in FIG.
Once turned on, the side heat response switch 12.26 is turned off, no unnecessary voltage is applied to the FEC 14, and deterioration of the FEC 14 can be suppressed.

However, there is a problem in that the lamp may not be able to be turned on when restarting the lamp.

In other words, when the lamp is on, the switch 12.26
Both are in the OFF state, but when the lamp is turned off and restarted, they are cooled down and the FECEC side thermally responsive switch 12 turns ON earlier than the auxiliary electrode side thermally responsive switch 26, the main electrode 24a and the starting auxiliary electrode 22 The FEC 14 starts oscillating before it is possible to discharge between the two. For this reason, a state in which it is difficult to start a discharge continues between the main electrodes 24a and 24b, and although a starting noise occurs due to the FEC 14, the arc tube 16 does not light up.

Furthermore, due to the temperature characteristics of FEC14, if the above-mentioned voltage continues to be applied, the pulse voltage will decrease due to self-heating (see IES of Au5tralia' 88, paper), making it increasingly difficult to restart the lamp. there were.

The present invention has been made in view of the problems of the prior art, and its purpose is to provide a metal halide lamp starting device that can prevent early deterioration of the FEC and reliably restart the lamp. It is in.

[Means for Solving the Problems] In order to achieve the above object, a metal halide lamp starting device according to the present invention includes a thermally responsive switch using a tungsten coil at one of the contacts that short-circuits the main electrode and the starting auxiliary electrode. It is characterized by

[Function] Since the metal halide lamp starting device according to the present invention has the above-described means, the main electrode and the starting auxiliary electrode are short-circuited during lamp lighting, so no unnecessary voltage is applied to the FEC. Furthermore, when the temperature is constant, the tungsten coil at one contact of the thermally responsive switch deforms, and no stress is applied to the bimetal. Therefore, the bimetal will not be deformed. On the other hand, when the temperature drops below a certain level, the deformed tungsten coil returns to its original shape, making it possible to reliably restart the lamp.

[Example] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIGS. 1A and 1B show circuit configuration diagrams of the present invention.

Note that parts corresponding to those in the prior art described above are indicated by the reference numeral 100, and their explanation will be omitted.

In the circuit shown in Figure (A), when the lamp is started, the thermally responsive switch 130 is composed of a three-contact switch, and the common contact (COM contact) 130c contacts the normally closed contact ('NC contact) 130a. , the NC contact 130
A voltage is applied to the FEC 114 through a to generate a pulse, which is passed through the starting resistor 120 to the main electrode 124.
b and the starting auxiliary electrode 122, and the main electrode 124a,
124b.

Next, while the lamp is lit, the thermally responsive switch 130 contacts the normal temperature open contact (No contact) 130b, and the main electrode 124
b and the starting auxiliary electrode 122 are short-circuited via the starting resistor 120, so no voltage is applied to the FEC 114 and the FE
Early deterioration of C114 can be prevented. Further, in this circuit, since there is no potential difference between the main electrode 124b and the starting auxiliary electrode 122 during lamp lighting, it is possible to prevent electrolytic phenomena during this time.

Then, when restarting the lamp, the thermally responsive switch 130
must be removed from the NO contact 130b before the NC contact 130
Since it comes into contact with a, it is possible to restart the lamp reliably.

Note that FIG. 1(B) shows a starting device for medium to high wattage, in which a parallel circuit of a semiconductor switch 140 and a resistor 142 is connected in series with the FECI 14.

Incidentally, although a bimetal is used as the thermally responsive switch 130, the following characteristics are required in the circuit shown in FIGS. 1(A) and 1(B).

a) When starting the lamp, the bimetal should be in contact with the NC contact 130a.

b) When the lamp is on (stable), the bimetal is in contact with the NO contact 130b.

C) When restarting the lamp, the bimetal first closes NO contact 13.
0b and when the temperature near the bimetal reaches approximately 80° C., contact the NC contact 130a. If the lamp is lit naked, the time must be within 15 minutes at 30 degrees Celsius with no wind.

d) After starting the lamp, the bimetal should be
Leave contact 130a and move <N as quickly as possible.

Contact the contact point 130b.

Further, in order to satisfy the above condition C), the thermally responsive switch 130 needs to be kept at a temperature of 2500C to 350C when the lamp is lit vertically above the cap.

By the way, a feature of the present invention is that a tungsten coil is used as one of the contacts that short-circuits the main electrode 124b and the starting auxiliary electrode 122. Therefore, with reference to FIG. 2, we will explain the case where a bimetal switch that satisfies each of the conditions a) to d) above is used alone without using a tungsten coil, and explain why the thermally responsive switch can be used in the device of the present invention. This section explains why tungsten coils are used and why they are necessary.

As an example, the bimetal of the thermally responsive switch 130 has the following characteristics.

Curvature constant (k) = 1,18X10-11 [℃] Elastic modulus (E) = 1,70xlO' [kg/mm2] Width (
b) = 4.0 [mml Thickness (t) = 0.25 [mm] Effective length L 1 = 15 [mm] Total length = 20 [mm] And width W between NC contact 130a and NC contact 130b
is 3.0mm.

If a tungsten coil is not used, the allowable stress of the bimetal of the thermally responsive switch 130 at around 300°C is 1
2 kg/mm2, and the bimetal has an NC contact of 130
As a result of calculating the allowable temperature rise after contact with b, it was 40℃
was found to be the limit.

That is, in the thermally responsive switch 130 having the structure shown in FIG. 2, the NC contact 130a,
It was necessary to adjust the distance between the NC contacts 130b.

However, thermally responsive switches that do not use tungsten coils have the following problems.

The thermally responsive switch having the above-mentioned characteristics has the contact 134 of the bimetal 132 connected to the NC contact 130a at 30°C.
If the contact pressure is maintained at a pressure of 0.g, the contact pressure becomes 0.0 g at about 80.degree. C., and at 250.degree. C., the bimetal 134 comes into contact with the No contact point 130b. Then, when the temperature further rises to 290℃, the bimetal 134 has a temperature of 12k.
g/mm" stress occurs, and if the temperature rises above that,
The allowable stress is exceeded, and even if the temperature drops, it does not return to its original state, and the NC contact 130a cannot be contacted when the lamp is restarted. As a result, restarting the lamp becomes difficult.

However, it is actually difficult to maintain the temperature of the thermally responsive switch 130 at 250'C to 290C while the lamp is lit. For example, the above temperature range may be exceeded due to fluctuations in the line voltage of the power supply that lights the lamp, changes in the ambient temperature of the lamp, and if the lamp is lit inside a fixture, the temperature may exceed 290'C. There is a high possibility that it will be exceeded.

Next, a thermally responsive switch used in the metal halide lamp starting device according to the present invention will be explained based on FIG. 3 showing a first embodiment of the present invention.

FIG. 3 shows an example of a thermally responsive switch in which a tungsten coil is attached to a bimetal.

The thermally responsive switch 130 according to the present invention has an effective length of 15 mm, a distance L2 between the COM contact 130C and the NC contact 130b of 20 mm, and a total length L3 of the sum of the length of the bimetal 130 and the length of the tungsten coil 150 of 30 m.
m, width W between NC contact 130a and NC contact 130b is 8
．． Omm.

The tungsten coil 150 was attached to the bimetal 132 because of the need to satisfy the following conditions.

■When starting the lamp, the thermally responsive switch leaves the NC contact 132a at approximately 80°C, and reaches approximately 200°C (even if the thermally responsive switch is installed in a part where the temperature exceeds 250°C when the lamp is lit vertically above the cap). , the temperature may only reach about 200° C. if the lighting direction is changed), and the No contact point 130b is contacted.

■When the lamp is turned off (restarted), the thermal response switch is approximately 20
Leaves the No contact 130a at 0°C, and closes the NC contact 1 at about 80°C.
30b.

No stress is applied to the bimetal at temperatures above 0200°C and up to 450°C (the maximum operating temperature of a bimetal that can be used as a thermally responsive switch).

In the thermally responsive switch 130 of FIG. 2, the pressure between both contacts at 30° C. is adjusted to 40±5 g so that the contact 134 of the bimetal 132 leaves the NC contact 130a at approximately 80'Ct. Then, when the temperature reached approximately 200℃ (
The state indicated by the dotted line A in the figure), the tungsten coil 150 is No.
Contact point 130b is contacted. When the temperature rises higher than that (for example, 450°C, as indicated by the dotted line B in the figure), the temperature difference from the initial contact will far exceed 40°C, but the bimetal 132 will deform due to the tungsten coil 150 deforming. No stress applied. Then, when the temperature drops to about 200 degrees Celsius, the deformed tungsten coil returns to its original shape.

FIG. 4 shows a second embodiment of the present invention, in which a tungsten coil is attached to a rod serving as an NC contact. Figure (A) is a side view, Figure (B) is a front view at room temperature, and Figure (C) is a front view at 450'C.

In this embodiment, the bimetal 232 fixed to the COM contact 230c is attached to the thermally responsive switch board 252, and the bimetal 232 is attached to the NC contact 230a.
, bimetal contacts 234 on both contact sides of the No contact 230b.
, 236.

Then, a tungsten coil 250 having a length 11 of 10 mm is attached to the NC contact 230b. At this time, the effective length L1 of the bimetal is 15 mm, and the NO contact 23ob and CO
M contact distance L2 is 20mm, tungsten coil 2
50 and the bimetal contact 236 on the No contact 230b side, the distance l is 2. It is Omm.

In this example as well, the bimetal 2
The contact 234 attached to No. 32 is set so as to contact the tungsten coil 250 on the No. contact 230b side.

The tungsten coil used in the two examples described above was a single (-type wound) coil with a coil inner diameter of 02 mmφ and a tungsten wire weight ffi of 35 mg and 7200 mm.

The wire diameter was 0.1 mmφ, and the mandrel ratio (coil inner diameter/wire diameter) was 1.9.

In addition, in the examples shown in FIGS. 3 and 4, the tungsten coil wire is a wire type ff118mg7200mm.
It was possible to use a wire with a wire diameter of 0.08 mmφ and a mandrel ratio of 2°6, but if the wire was smaller than that, the coil would not be straight and would hang, so it was difficult to use it as a contact point. It was impossible to do so.

Furthermore, the wire weight is 70 mg, 7200 mm, and the wire diameter is 0.
゜15mmφ, mandrel ratio 3.3 (coil inner diameter 0゜5
mmφ), wire weight 120mg7200mm, wire diameter 0.20mmφ, mandrel ratio 4.5 (coil inner diameter 0.
It was also possible to use a coil of 9 mmφ). However, in order to use a wire with a heavier wire weight, the mandrel ratio must be set to 4.5 or more, which causes the coil to sag due to its own weight, making it impossible to use it as a contact point.

If the wire of a tungsten coil is used as a contact point without being coiled, the wire will be plastically deformed in its shape at 450 degrees Celsius, and will not return to its original shape even when the temperature drops. The device could not be used.

In each of the embodiments described above, the thermally responsive switch of the present invention is used as a two-contact type switch, but it is also possible to use this as a two-contact type switch.

[Effects of the Invention] As explained above, according to the metal halide lamp starting device according to the present invention, a tungsten coil is used as one of the contacts that short-circuits the main electrode and the starting auxiliary electrode. deforms and no stress is applied to the bimetal. When the temperature drops below a certain level, the deformed tungsten coil returns to its original shape, allowing the lamp to restart.

[Brief Description of the Drawings] Figures 1 (A) and (B) are circuit configuration diagrams of the present invention, Figure 2 is a configuration diagram of a bimetal switch, and Figure 3 is a diagram showing the first embodiment of the present invention. FIG. 4 is an explanatory diagram showing a second embodiment of the present invention, and FIG. 4A is a side view and FIG.
) is an explanatory diagram showing the room temperature condition, FIG. 7 is a circuit diagram of the third conventional device, and FIG. 8 is a waveform diagram of the voltage applied to the FEC. 130, 23 130a, 2 130b, 2 132.23 150, 25 0... thermal response switch, 30a... NC contact, 30b... NO contact, 2... bimetal, 0... tungsten coil.

Claims (1)

[Claims] (1) In a metal halide lamp starting device comprising a metal halide lamp equipped with a main electrode and an auxiliary starting electrode, and a nonlinear capacitor capable of applying a pulse voltage between the main electrodes, a contact that short-circuits the main electrode and the auxiliary starting electrode. A metal halide lamp starting device characterized in that one side of the metal halide lamp is equipped with a thermally responsive switch using a tungsten coil.