JPS5956396A - Method of starting discharge lamp - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge lamp starting method for starting a cold cathode high pressure discharge lamp using high frequency and high voltage, and particularly to a discharge lamp starting method for restarting a metal halide lamp or the like in a hot state immediately after being turned off. Regarding the method.

When starting and lighting a high-pressure discharge lamp using a commercial power source, generally, as shown in Figure 1, a current limiting choke 2 is connected to the commercial AC power source 1.
The discharge lamp 3 is continued continuously through the discharge lamp 3.

The discharge lamp 3 has an arc tube housed in an outer bulb. In addition to a pair of main electrodes, a normal arc tube has an auxiliary starting electrode adjacent to one of the main electrodes, and a main electrode opposite to the auxiliary starting electrode. A potential is applied through a high resistance to generate a glow discharge. If necessary, a starting means 4 is connected in parallel to the discharge lamp 3. However, providing a starting auxiliary electrode to the arc tube not only complicates the structure of the arc tube itself, but also complicates the structure inside the outer bulb, which is not only difficult to manufacture, especially for small-power lamps. Characteristic 2 also has the disadvantage of reduced efficiency. In addition, although it is possible to start the lamp for the first time using the power supply voltage application method, even if you try to turn off the discharge lamp that is already lit and then restart it when the lamp is turned on,
Instant restart was not possible because the vapor pressure inside the arc tube was extremely high and the restart voltage was also significant. Even when starting means 4 was used, instantaneous restart was not possible. T-kari V? Even if instantaneous restart is possible, it requires an extremely high voltage, which poses practical difficulties in terms of insulation, etc. In contrast, the present applicant has proposed that, as a starting means for the hot cathode low pressure discharge lamp 3a, a series circuit of a boost inductor 6 and a thyristor 7 is connected in parallel to the oscillation capacitor 5, as shown in FIG. It is proposed to use a boost oscillator circuit 8. Although this step-up oscillation circuit 8 is an excellent starting means for the hot cathode low-pressure discharge lamp 3a, the step-up ratio is insufficient as an instantaneous restart means for the cold cathode high-pressure discharge lamp 3, and this -! - cannot be used.

Therefore, the main purpose of this invention is to facilitate instantaneous restart of a cold cathode high-pressure discharge lamp and reduce the time of extinguishment (unlit time).
An object of the present invention is to provide a discharge lamp starting method that can shorten the time.

In summary, this invention converts a commercial AC power supply voltage into a high frequency high voltage and applies it to a cold cathode high pressure discharge lamp, and a pair of electrodes of the cold cathode high pressure discharge lamp is configured so that the capacitance between them increases. The present invention is characterized in that the discharge breakdown is promoted by the high-frequency displacement current.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 shows a block diagram of a discharge lamp lighting device using the discharge lamp starting method sound of the present invention. In the figure, IO is a commercial low frequency AC power supply, 11 is a current limiting device housing, 12 is a conversion circuit that converts the low frequency AC power supply voltage "f" to a high voltage of the same frequency, and 13 is a start-up when the output of the conversion circuit 12 is applied. This is a cold cathode high pressure discharge lamp.

FIG. 4 is a specific circuit diagram of one embodiment of FIG. 3. In the figure, the current limiting device 11 is composed of a single choke coil, that is, a current limiting choke.

The conversion circuit 12 basically consists of two parts. One of them is an intermittent boost oscillation circuit 80 whose basic circuit is the boost oscillation circuit 8 shown in FIG. That is what we are doing. The other one is a high frequency voltage boosting means 14 that boosts the high frequency voltage generated by the intermittent oscillation capacitor 9, and the illustrated example is constituted by a series resonant circuit consisting of a series circuit of an inductor 15 and a capacitor 16.

FIG. 5 shows an arc tube 13a of a cold cathode high-pressure discharge lamp 13, in which seals are provided at both ends of an arc tube body 17 made of quartz.
a, l 9, made of nickel, 1 outgoing wire 20
21 is electrically connected to a pair of tungsten lead-in wires 24, 25 via molybdenum foils 22, 23 and hermetically sealed. A tungsten electrode 26.2 containing thorium is provided at the inner end of each lead-in wire 24°25.
7 are arranged with a relatively short facing distance (about 5 ms) and a large facing area so that the total capacitance between them is increased. Inside the arc tube body 17, iodides such as mercury, sodium, scandium, etc. are sealed together with a rare gas such as argon.

In the above configuration, when the low frequency AC power supply 10 is connected, the oscillation capacitor 5 is charged via the current limiting choke 11, and when the terminal voltage reaches the breakover voltage "BO" of the thyristor 75-, the thyristor 7 becomes conductive. , due to the cooperation of the oscillation capacitor 5 and the boost inductor 6, 100KHz is applied across the oscillation capacitor 5.
A high frequency and high voltage that includes the above harmonics and is about 8 times the power supply voltage is generated. This step-up oscillation operation is performed intermittently every half cycle of the low frequency AC power supply voltage due to the presence of the intermittent oscillation capacitor 9. This intermittent boost oscillation circuit 8
The high frequency high voltage output from the high frequency high voltage means 14
The voltage is further increased to about 6 times by 1, and applied to the cold cathode pressure discharge lamp 13. At this time, the voltage applied to the cold cathode high pressure discharge lamp 13 is a high frequency of 100 KH2 or more and a high voltage of loKV or more, and the pair of electrodes of the cold cathode high pressure discharge lamp 13 is connected to the electrode 26.2.
7 facing each other to increase the capacitance between the electrodes 26 and 27, the electric field between the electrodes 26 and 27 is reduced to E.
, when the dielectric constant is ε, the displacement current of 61δt = ” ”/us increases according to Maxwell's electromagnetic equation,
This displacement current activates the gas in the space of the electrodes 26, 27i4j, and increases the current that serves as a trigger, thereby promoting discharge destruction. When the arc tube 13a is destroyed by discharge, the glow discharge changes to the arc discharge, but the general oscillation circuit
As shown in curve 1 shown by the dotted line in the figure, as the load increases, the load supply power decreases rapidly. 8), as shown in curve 2 shown by the solid line in the figure, contrary to the above, the load supply power increases as the load increases, so it inevitably shifts to arc discharge. Therefore, a very low internal impedance is obtained, and sufficient energy can be supplied to the arc tube 13 during the transition from glow discharge to arc discharge, so that the cold cathode high pressure discharge lamp 13 can be easily started and lit.

Thereafter, when the power switch (not shown) is opened to turn off the cold cathode high pressure discharge lamp 13, and the power switch is turned on again, the conversion circuit 12 is activated again to generate high frequency and high voltage, and the cold cathode high pressure discharge lamp 13 is turned off. 13. In the cold cathode high pressure discharge lamp 13, the electrode 2
A displacement current flows between 6.27 and 27. For this reason, whereas normal heat damage starting requires a high DC voltage of about 20 KV, the conditions for instantaneous restart of the cold cathode high pressure discharge lamp 13 can be satisfied with relatively low high frequency IT pressure and energy. The cold cathode high-pressure discharge lamp 13 can be restarted instantaneously or in a short period of time without a starting auxiliary electrode. By simply generating a high frequency and high voltage of about 10 KV using the conversion circuit 12, it is possible to instantaneously restart a high pressure mercury lamp or a high pressure sodium lamp, but instantaneous restart of a metal halide lamp is unstable. By configuring the cold cathode high pressure discharge lamp 13 as described above, stable restart of the metal halide lamp is also possible due to the synergistic effect with the high frequency and high voltage.

As described above, according to the embodiment shown in FIG. 4, the intermittent boost oscillation circuit 8
0 contains a high frequency of 100 KHz or more and converts it into a voltage of about IKV, and uses this high frequency voltage and the high frequency voltage boosting means 14 to boost the voltage to 10KV or higher in two steps, and also increases the capacitance between opposing electrodes of the cold cathode high pressure discharge lamp 13. Due to this increase, not only high-pressure mercury lamps and high-pressure sodium lamps but also metal halide lamps can be started easily and reliably for the first time and instantaneous restart. Moreover, the intermittent boost oscillation circuit 80 and the high frequency voltage boost means 14 are small and
Can be configured at low cost. In particular, although the output frequency of the intermittent boost oscillation circuit 80 is approximately several tens of KHz, the output voltage waveform has a sawtooth waveform and includes harmonics of 100 KHz or more. Inductor 15 and capacitor 1 are connected to each other for series resonance.
By setting a constant of 6, the high frequency voltage boosting means 14 can be further miniaturized.

The seventh example shows a circuit diagram of a different embodiment of a discharge lamp lighting device for carrying out the starting method of the present invention.

The figure is similar to FIG. 4 except for the following points, and the same parts are given the same reference numerals. This embodiment differs from FIG. 4 in that a positive bias winding 6a' is connected to the boost inductor 6 in the intermittent boost oscillation circuit 809-.
tet magnetically coupled, and this positive bias winding fix6
A is connected in series with the oscillation capacitor 5 to generate a predetermined high frequency voltage using a smaller boost inductor. Further, a discharge resistor 29 is connected in parallel to the intermittent oscillation capacitor 9. Furthermore, a parallel circuit of a second thyristor 30, a resistor 32, and a capacitor 33 is connected in series to the intermittent boost oscillation circuit 8o. Further, the high frequency voltage boosting means 14' is constructed of a high frequency saturable transformer. The high frequency saturable transformer has a primary winding 34 and a secondary winding 35, and the primary winding 34 is connected in parallel to a series circuit of a low frequency AC current 111o and a current limiting choke through a capacitor 36. ing. Secondary winding 3
It is connected in series to five cold cathode high pressure discharge lamps 13.

In the above configuration, when the low frequency AC power supply 10 is connected, the low frequency AC power supply 1o - the current limiting station 11 - the capacitor 33 - the positive bias winding 6a - the oscillation capacitor 5 -
The oscillation capacitor 5 is charged through the path 10 and 10, and the capacitor 3
The capacitor 36 is charged through the path of the 6-primary winding 34-10. Thus, when the terminal voltage of the oscillation capacitor 5 and/or capacitor 36 reaches the breakover voltage of the thyristor 7, the thyristor 7 becomes conductive, and due to the cooperative action of the oscillation capacitor 5 and/or capacitor 36 and the boost inductor 6, the voltage is intermittently boosted. The oscillation circuit 8o starts boost oscillation operation and becomes low impedance, and the resistor 32
Thyristor 3o becomes conductive due to an increase in the partial pressure of . Write 1
In ~, the intermittent boost oscillation circuit 80 intermittently generates a high frequency voltage in the same way as described above, and in response, a high frequency pulse current flows through the primary winding 34 of the high frequency saturable transformer. The generated pulse voltage is induced to rise in the secondary winding 35 and is applied to the cold cathode high pressure discharge lamp 13.

In this way, when the high-frequency voltage step-up means 14 is constituted by a high-frequency transformer, the step-up ratio can be freely set by changing the turns ratio between the primary winding 34 and the secondary winding 35, and the saturable structure allows the turns number to be set freely. It can be made smaller compared to the ratio.

In the above embodiment, the thyristor 30 has an inner tube temperature of approximately 200°C during the starting process of the cold cathode discharge lamp 13.
When the voltage reaches a certain level, the restrike voltage increases to prevent the intermittent boost oscillation circuit 80 from malfunctioning. Moreover, it is for sequentially conducting the thyristors 7 and 3° of 32 resistors in the order just described, and is connected in parallel to the thyristor 7.
The thyristors 30.7 may be made conductive in sequence.

Furthermore, in each of the above embodiments, the cold cathode high pressure discharge lamp 1
After the start of step 3, the operation of the intermittent boost oscillator circuit 80 is completely stopped, and therefore, in the path of low frequency AC current 11o - current limiting choke 11 - inductor 15 (or secondary winding 35) - cold cathode high pressure discharge lamp 13 - 10, A low frequency lamp current is supplied to the cold cathode high pressure discharge lamp 13 to keep it lit. However, if the voltage of the low frequency AC power supply 1o is
If the voltage is set approximately equal to the tube voltage in step 3, the intermittent step-up oscillator circuit 8o will operate every half cycle of the low-frequency AC power supply voltage to generate a full high-frequency voltage 5, which will be boosted by the high-frequency voltage step-up means 14. Cold cathode high pressure discharge lamp with high frequency and high voltage 1
Re-ignite 3. It is also possible to turn on the light using a so-called half-cycle start lighting method.

Although a specific embodiment has been described as the conversion circuit 12, any circuit can be used as long as it has the function of converting a low frequency AC power supply voltage to a high frequency high voltage.

FIG. 8 shows a sectional view of an arc tube 13b of a cold cathode high pressure discharge lamp according to another embodiment of the present invention. That is, two lead-out wires 20, 21 and lead-in wires 24.degree. 25 were drawn out in parallel and in the same direction. It has a so-called single-ended structure, and a ring-shaped heat-resistant dielectric 28 is used to increase the capacitance between the electrodes, and coil-shaped electrodes 37 and 38 are formed by winding the ring-shaped heat-resistant dielectric 28 on opposing parts. It is the same as FIG. 5 except for. Even in such an embodiment, the same effects as in FIG. 5 can be obtained.

As described above, this invention converts a low frequency AC power supply voltage into a high frequency high voltage, and converts this high voltage into a high voltage with a counter electrode arranged so as to increase the total capacitance between the two. Since the electric current is applied to the cold cathode high pressure discharge lamp and the displacement current between the opposing electrodes causes the cold cathode high pressure discharge lamp to achieve discharge breakdown, it can easily and reliably apply to not only high pressure mercury lamps and high pressure sodium lamps but also metal halide lamps. This has the effect of allowing initial starting and instantaneous restart.

[Brief explanation of the drawing]

Figures 1 and 2 are circuit diagrams of a conventional discharge lamp lighting device;
Fig. 3 is a block diagram of a discharge lamp lighting device implementing the starting method according to the invention, Fig. 4 is a circuit diagram of a specific embodiment of Fig. 3, and Fig. 5 is a light emission of a cold cathode high-pressure discharge lamp used in the invention. Of the tube! Figure 6 is a characteristic curve diagram of load versus load supply power depending on the type of oscillator, Figure 7 is a circuit diagram of another discharge lamp lighting device according to this invention, and Figure 8 is a cold cathode high voltage used in this invention. FIG. 3 is a sectional view of an arc tube of another embodiment of the discharge lamp. -14- 10...Low frequency AC power supply, 11...Current limiting device (current limiting choke), ]2...
・Conversion circuit, Co-3...Cold cathode high pressure discharge lamp, 13a, 1
3b... Arc tube, 14... High frequency voltage boosting means, 26.27... Electrode\ 28... Heat resistant dielectric, 3'7.38... ...Coil-shaped electrode, 80...
・Intermittent boost oscillation circuit. Patent Applicant Shin Nippon Electric Co., Ltd.

Claims (1)

[Claims] The conversion circuit includes a low frequency AC power supply, a current limiting device, a conversion circuit that converts the low frequency AC power supply voltage to high frequency high voltage, and a cold cathode high pressure discharge lamp to which the high frequency high voltage of the conversion circuit is applied. The high frequency output includes a high frequency component that promotes high frequency displacement current between opposing electrodes of the cold cathode high pressure discharge lamp, and the opposing electrodes of the cold cathode discharge lamp are configured to increase the capacitance between them. A method for starting a discharge lamp, characterized in that discharge destruction is promoted by a high-frequency displacement current between electrodes.