JPS63150891A - Discharge lamp lighter - 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]

[Technical Field] The present invention relates to a discharge lamp lighting device for operating a 7α discharge lamp that requires a high pulse voltage at the time of starting.

[Background technology]

FIG. 3 shows a conventional example of a lighting device for a discharge lamp that requires a high-voltage pulse at startup. Here, vl is an AC power supply, CH is a choke coil, and DL is a discharge lamp that requires a high-voltage pulse when starting. The α lamp circuit is mainly composed of the AC power supply ■1, the choke coil CH, and the discharge lamp DL. ing. This discharge lamp lighting device includes a discharge lamp starting circuit 2 for lighting the discharge lamp DL.
Charge is supplied to the capacitor C1 via the capacitor C1. Windings N and N2 of choke coil CH (N 1 < N
2) and is used as a transformer 1, and this tap is connected to the capacitor C1 mentioned above.
is connected, and a triac Q1 is connected to the midpoint between the capacitor C1 and the resistor R1 and the opening between the choke coil CH, and an imaging circuit is configured by the winding N1 of the choke coil CH and the capacitor C1. Yes, capacitor C! The electric charges charged in the triac Q1 are discharged as a pulsed current through the winding N1 by conduction of the triac Q1. Q2 is a voltage responsive switch of a thyristor (SSS), which is drawn out from the midpoint between a capacitor C2 and a resistor R2, which are inserted in parallel with the discharge lamp DL, and is connected to the date of the triac Q1. When the voltage charged in the capacitor C2 from the AC power source V1 via the resistor R2 reaches the breakover voltage of the voltage responsive switch Q2, the voltage responsive switch Q2 breaks over and becomes conductive, turning on the triac Q1. When the triac Q becomes conductive, the charge stored in the capacitor C5 is released as a pulsed current through the winding #iN, and the pulsed current is caused by the pulsed current')8! The voltage generated in MN is applied to the outside by winding #iN2, and therefore a high voltage pulse is generated in the choke coil CH. This high voltage pulse is superimposed on the voltage of the AC power supply Vl and is applied to the discharge lamp DL, resulting in discharge. The electric light DL is started by applying a high voltage pulse and enters a lighting state. When the discharge lamp DL enters the lighting state, the voltage decreases and the main lighting circuit maintains the α lamp state. Fourth
The figure shows main waveforms in the electric circuit of FIG. 3. The figure (a) shows the voltage waveform of the AC power supply ■, which is a sine waveform, and the figure (b) shows the voltage Vc2 across the capacitor C2, which is the time t1 from the zero point of the AC power supply ■.
Later, the breakover voltage of the voltage responsive switch Q2 is reached, and at this time the voltage responsive switches Q2 and 1 are activated.
This indicates that conduction occurs. FIG. 4(C) shows the pulse current IQ1 flowing through the triac Q after the triac Q1 is turned on, and this waveform becomes a damped oscillation with a resonant frequency approximately determined by the constants C1 and N of the oscillating circuit. ing. Figure (d) shows the voltage Vch generated across the choke coil CH, and since the voltage generated at the winding #IN is boosted to the winding #[N2 by electromagnetic induction, the voltage Vch generated at the choke coil CH is becomes a damped oscillating high-voltage pulse as shown in FIG. 2(d). The one shown in FIG. 5 is another conventional example, and the same elements are given the same reference numerals (the same applies hereinafter). The difference between the electric circuit in Figure 5 and the electric circuit in Figure 3 is that in the electric circuit in Figure 3, the choke coil CH serves both as a current limiter and as an external pressure generator for generating high-voltage pulses. In the electric circuit shown in Figure 5, the current limiting choke coil C
The point is that H' and the pulse transformer PT used as the external voltage transformer 1 for generating high voltage pulses are separated and made independent. In other words, in the conventional example shown in Fig. 3, the sum of the number of turns N l + N 2 of the windings of the choke coil CH is automatically determined from the inductance value required for current limiting, so the required high voltage pulse height is Since it was not possible to determine the ratio of N1 and N2 to obtain the desired height and width, and it was not possible to obtain a good design point, the choke coil CH' and the pulse transformer PT were separated in the conventional example shown in Fig. 5. . As a result,
The current limiting constant is determined only by the choke coil CH',
In the pulse transformer PT, the number of turns N, N2 of the winding can be determined only by the conditions necessary to obtain the necessary waveform, and the degree of freedom in designing for generating high voltage pulses is increased. The next figure, ttIJ6, further shows a conventional example of a pond. This is an attempt to light the discharge lamp DL using the DC power source (2). In this electronic circuit, one chip circuit is constituted by the DC power supply ■2, the switching element Q3, the choke coil CH2, the capacitor C3, and the switching element Q, and the DC power supply ■2 and the switching element Q4
The other chopper circuit is constituted by the capacitor c:l, the choke filter CH2, and the switching element Q6, and the switching element Q, the switching element Q,
is performing high frequency switching operation. Also, Dl,
D2. DtyD4 is a conventional flow guide. Therefore, when the switching element Q is closed and the switching element Q6 is opened, a substantially DC voltage is generated across the capacitor C1 due to the high frequency switching of the switching element Q, and conversely, the switching element Q6 is When the capacitor C3 is closed and the switching element Q5 is opened, a substantially DC voltage having a polarity opposite to that in the above case is generated across the capacitor C3 due to high frequency switching of the switching element Q4. Therefore, by alternately opening and closing the switching element Q5 and the switching element Q6 at a constant frequency, the switching element Q is connected to both ends of the capacitor C3.
A rectangular wave AC voltage having the same frequency as the switching frequency of stQ is generated. Since the capacitor C1 equivalent to this AC power source is connected to the discharge lamp starting circuit 2 which operates in the same way as the discharge lamp and α lamp circuit shown in Fig. 5, the discharge lamp DL is stably lit at 7α. be. By the way, when we examine the occurrence of high-voltage pulses in the three conventional examples shown in Figs. 3, 5, and 6, we find the following.6 Fig. 7(a) shows that the triac Q, Fig. 7(b) shows the waveform of the current IQ+ flowing in the pulse transformer PT shown in Fig. 4(b), which is greatly enlarged in the time axis direction. The waveform of voltage Vn2 is greatly expanded in the time axis direction, but as shown in the figure, current IQ+ and voltage Vn2 have a frequency higher than the frequency of the oscillating circuit determined by the constants of winding N1 and capacitor C3 during lighting operation. A vibration waveform is shown, and a high-voltage pulse with a higher frequency than intended in the design appears above the design waveform indicated by the broken line. Generally, in order to start the discharge lamp DL, a high voltage pulse applied to the discharge lamp DL is opened for a certain period of time. A certain level above ■. Must be maintained at a higher level. In other words, the time it takes for arc discharge to start from one end of the discharge lamp DL and reach the other end until the arc discharge stabilizes within the discharge lamp DL, or the energy required to cause stable arc discharge to the discharge lamp DL. The high voltage pulse needs to be maintained at a constant level for longer than the time required to supply it. For this reason, even if the constants of winding IIANl and capacitor C1 are designed to ensure stable lighting operation, in reality, the vibration frequency is larger than the shiko design frequency as shown in Figure 7 (a) and (b). When a high voltage pulse occurs,
■Constant high-voltage pulse bell. There is a problem in that the above maintenance time T becomes short and the actual discharge lamp DL cannot be started reliably. As a result of investigating this cause, the applicant of the present invention discovered the first conventional example (Fig. 3).
It was determined that this is due to stray capacitances jl Cs I, CS 2 parasitic to the choke coil CH of , and the pulse transformers PT of the second conventional example (FIG. 5) and the third conventional example (FIG. 6). That is, as shown in FIGS. 8(a) and 8(b), floating capacitances flcs, cs2 are placed on the choke coil CH and pulse transformer PT, and this capacitance Cs
Since the value of I t CS 2 is generally much smaller than the value of capacitor CI, it is a manifestation of large frequency parasitic oscillations. The above problem becomes a big problem, especially in a circuit like the one shown in FIG. That is, when configuring a discharge lamp lighting circuit using an electronic circuit, it is necessary to reduce the inductance in order to make the device lighter and smaller, but reducing the inductance increases stray capacitance. Also, a certain level ■. In order to widen the above time width T1, it is possible to increase the peak value of the high voltage pulse generated by the choke coil CH or pulse transformer PT, but this may cause problems with the withstand voltage of other electrical components, and Using electrical components will increase the cost, or it may be possible to increase the capacitance of the capacitor C1 to increase the period of the basic oscillating circuit, but this will increase the capacitance of the capacitor C1 and increase the price. There was a problem.

[Purpose of the invention]

The present invention has been made in view of the technical background of vehicle collection, and its purpose is to reduce the frequency of vibrations parasitic to the lighting voltage applied to discharge lamps and to release The goal is to ensure that electric lights are turned on properly.

[Disclosure of the invention]

The discharge lamp lighting circuit of the present invention includes a discharge lamp starting circuit 2 in which at least a discharge lamp DL that requires a high voltage pulse at startup and a high voltage side winding N2 of a transformer 1 for generating high voltage pulses are present in a closed circuit. A discharge lamp lighting device including a capacitor capable of maintaining an applied voltage at a voltage level necessary for starting the discharge lamp DL for a necessary time at a frequency lower than the parasitic oscillation frequency at the time of starting the discharge lamp starting circuit 2. The capacitor C1 is the low voltage side winding of the transformer 1! It is characterized in that it is connected to at least one of the wire N and the high voltage side winding N2. By connecting the capacitor C1 to the transformer 1, the small stray capacitance Cs parasitic to the transformer 1 can be reduced.
,, the combined capacitance of Cs2 and this capacitor C1 can be increased, and by increasing the combined capacitance, the period of the high frequency pulse parasitic to the voltage applied to the discharge lamp DL can be reduced, and the period of the high frequency pulse parasitic to the voltage applied to the discharge lamp DL can be reduced. A constant level of voltage required to stably light the DL ■. The voltage applied to the discharge lamp D can be maintained for a long time.
Since the capacitance of the capacitor C4 is selected in such a way that the time required for L is reliably longer than the time required to turn on the α lamp, the discharge lamp DL can be reliably turned on. Moreover, since the transformer 1 is simply loaded with the capacitor C1, the electrical circuit does not become complicated, and the discharge lamp starting circuit 2
There is no need to increase the capacity of the capacitor C1 for the external voltage, and there is no need to increase the peak value of the high voltage pulse generated in the transformer 1. Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. What is shown in FIG. 1 is an embodiment of the present invention, in which a capacitor C4 is connected to both sides of the winding N on the low voltage side of the pulse transformer PT in the electrical circuit shown in FIG. 5 as a conventional example. be. Therefore, the operation is similar to that shown in FIG. 5, but only the pulse transformer PT
By connecting the capacitor C1 to the stray capacitance Cs,
The combined capacitance of the capacitor C4 and the capacitor C4 increases, and therefore the frequency of parasitic vibrations on the high voltage pulse of the pulse transformer PT decreases. FIG. 2(a) shows the waveform of the current rQ+ flowing through the triac Q1, greatly expanded in the time axis direction, and FIG. 2(b) shows the waveform of the current rQ+ flowing through the triac Q1.
The figure shows the waveform of the voltage Vch of the high voltage pulse generated at both ends of H, greatly expanded in the time axis direction. ■The voltage level required for starting from the high voltage pulse peak. The time T2 required for the voltage to drop to f? ! It is longer than IT, and the capacity of capacitor C1 remains the same, and the voltage peak value does not become extremely large, ensuring discharge lamp DL.
can be started. In other words, the capacitance of the capacitor C1 is such that the parasitic frequency at the time of starting the discharge lamp starting circuit 2 can be reduced, and the voltage can be reduced from the peak level to the level required for starting the discharge lamp DL.
. The time T2 (pulse width at level V) required to start the discharge lamp DL while the time T2 is maintained at . It is selected so that it is larger than . Note that the capacitor C4 may be connected to the high voltage side winding plAN2, or may be connected to both windings #tN, , N2. In addition, the capacitor C4 may be connected to the choke coil CHLy′) winding @N , , N 2 of the electric circuit shown in FIG. A capacitor C1 may be connected to the windings N2, N2.

【Effect of the invention】

As described above, the present invention provides a discharge lamp lighting device including a discharge lamp starting circuit in which a discharge lamp that requires a high-voltage pulse at the time of starting and a high-voltage side winding of a transformer for generating high-voltage pulses are present in a closed circuit. , a capacitor having a frequency lower than the parasitic oscillation frequency at the time of starting the discharge lamp starting circuit and having a capacity capable of holding the applied voltage at the voltage level necessary for starting the discharge lamp for the necessary time is connected to the low voltage of the transformer. Since it is connected to at least one of the side winding and the high voltage side winding, the combined capacitance of this capacitor and the small stray capacitance parasitic to the transformer can be increased, and the combined capacitance can be increased. By doing so, it is possible to reduce the period of the high-frequency pulse that is parasitic to the voltage applied to the discharge lamp, and to maintain the applied voltage for a long time at a constant level of voltage necessary to stably light the discharge lamp. Since the capacity of the capacitor is selected so that this maintenance time is longer than the time required to reliably light the discharge lamp, it is possible to reliably light the discharge lamp. Furthermore, since the transformer is simply loaded with a capacitor, the electric circuit does not become complicated, and the vR of the boost capacitor in the discharge lamp starting circuit does not need to be increased. Furthermore, the peak value of high voltage pulses generated in the transformer is not increased.

[Brief explanation of the drawing]

Fig. 1 is an electric circuit diagram showing one embodiment of the present invention, Fig. 2 is a waveform diagram for explaining the operation of the same as above, Fig. 3 is an electric circuit diagram of a conventional example, and Fig. 4 is the main waveform of the same as above. FIG. 5 is an electric circuit diagram of another conventional example, FIG. 6 is an electric circuit diagram of still another conventional example, FIG. 7 is an enlarged view of a part of FIG. 4, and FIG. 8 ( FIGS. 2A and 2B are explanatory diagrams showing stray capacitances parasitic in a choke coil and a pulse transformer, respectively. 1...Transformer, 2...Discharge lamp starting circuit, N,, N2
・・・Transformer winding, C1...Capacitor, DL・
...discharge lamp. Agent Patent Attorney Ishi 1) Go to Figure 7, Figure 2, Figure 5, Figure 6 \ O 0, Ω Q ℃ Figure 7, Figure 8 CG)

Claims (1)

[Claims] (1) In a discharge lamp lighting device including a discharge lamp starting circuit in which a discharge lamp that requires a high-voltage pulse at least at startup and a high-voltage side winding of a transformer for generating high-voltage pulses are present in a closed circuit, the discharge lamp A capacitor having a frequency lower than the parasitic vibration frequency at the time of starting the starting circuit and having a capacity capable of maintaining the applied voltage for the necessary time at the voltage level necessary for starting the discharge lamp is connected to the low voltage side winding of the transformer. A discharge lamp lighting device characterized by being connected to at least one of the high-voltage side windings.