JPH0328795B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a starting pulse generator for a discharge lamp lighting device.

[Background technology]

2. Description of the Related Art Conventional lighting devices for discharge lamps that require a high voltage pulse for starting are shown in FIGS. 1 and 2. In other words, in the one in Figure 1, ballast B and discharge lamp L are connected in series to AC power supply V _S , and a series circuit of capacitor C and triac Q is connected to primary winding a of ballast B. form a primary circuit. T is a trigger circuit. When the switch Q is turned on at any phase of the AC power supply V _S when the discharge lamp L is not lit, a closed loop is formed between the AC power supply V _S , the primary winding a of the ballast B, and the capacitor C. , in this closed loop, an oscillating current flows from the AC power supply V _S by the inductance of the primary winding a and the capacitor C, and at this time, the voltage generated in the primary winding a has a larger number of turns than the primary winding a. A pulse voltage is generated across the discharge lamp L by boosting the voltage in the secondary winding.

However, since this pulse generator generates pulses using an oscillating current, it has the drawbacks of large fluctuations in the power supply voltage and large noise that is fed back to the AC power supply _VS.

The one in Figure 2 connects a capacitor C' and a triax Q' in series to both ends of the primary winding a of ballast B, and connects a resistor R to the connection point between them to form a primary circuit. ing. When the discharge lamp L is not lit, when the triax Q' is turned on at any phase of the AC power supply V _S , the capacitor C' is originally connected to the AC power supply V _S
Since the capacitor C' is charged through the resistor R, the capacitor C' is discharged in the closed loop of the capacitor C', the triax Q', and the primary winding a of the ballast B, and at this time, 1
The voltage generated in the secondary winding a is boosted to the secondary winding, which has a larger number of turns than the primary winding a, so that the discharge lamp L
A pulse voltage is generated across the . In this device, since the oscillating current is not involved in pulse generation as described above, fluctuations in the pulse voltage value with respect to fluctuations in the power supply voltage are improved.

However, after the discharge lamp L is lit, that is, when the triax Q' is always off, current flows through the closed loop of the AC power supply V _S , the capacitor C ₁ and the resistor R, and there is a drawback that power loss occurs due to the resistor R. .

[Purpose of the invention]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a starting pulse generator for a discharge lamp lighting device that suppresses fluctuations in pulse voltage due to fluctuations in power supply voltage and eliminates power loss after lighting.

[Disclosure of the invention]

In this invention, the capacitive element sides of the first and second charging circuits are connected to both ends of the primary winding of an autotransformer to which a secondary voltage is applied to the discharge lamp, and each charging circuit has opposite polarity. A rectifier element is connected in series to a capacitive element, and a switch means is connected between the connection points. For this reason, when the switch means is turned on, each capacitive element and the single-winding transformer are
A closed loop is formed by the next winding, and the capacitive element is discharged, thereby generating a pulse voltage on the secondary side of the autotransformer. Therefore, pulse voltage fluctuations due to power supply fluctuations are small, and since there is no resistance in the charging circuit after the pulse voltage is stopped, there is no power loss. Furthermore, since there are two capacitive elements, it is easier to generate high voltage pulses, and the pulse width and height can be obtained at the same time.

A discharge lamp lighting device to which a first embodiment of the present invention is applied is shown in FIGS. 3 and 4. In other words, its basic configuration is two capacitors (capacitive elements) C ₁ ,
A closed circuit consisting of C ₂ , the primary winding a of the ballast (autotransformer) B, and the triax Q ₁ which is the switching means, and when the triax Q ₁ is in a non-conducting state, the AC power supply V _S and the two Capacitor C ₁ , C ₂
It is composed of two charging circuits via diodes (rectifiers) D ₁ and D ₂ so that the diodes (rectifiers) D 1 and D 2 are charged in opposite directions. Furthermore, L ₁ is a lamp that does not require preheating, such as an HID lamp, and T ₁ is a trigger circuit.

In operation, when the S ₁ end of the AC power source V _S (Figure 4a) is positive, the capacitor C ₁ has been charged during the previous half cycle as shown in Figure 4d, and the capacitor C 1 is charged as shown in Figure 4d.
_C2 is charged as shown in Figure 4e. At this time, the charging path of the capacitor _C2 is performed from the AC power supply V _S via the primary winding a of the ballast B and the diode _D2 . When the lamp _L1 is not lit, _the voltage across the lamp _VD is _VSVD , as shown in FIG. 4f. Also, in the trigger circuit _T1 , the capacitor _C3 is charged via the resistor _R1 (FIG. 4b). The trigger circuit T ₁ is set so that the triac Q ₁ becomes conductive at an arbitrary phase angle during a half cycle of the AC power supply V _S and becomes non-conductive within at least that half cycle, and the voltage of the capacitor C ₃ V _C3 When _Q2 reaches the response voltage of a bidirectional voltage-responsive switching element (DIATSU, SSS, SBS, etc.), it turns on and the capacitor
A discharge current flows from C ₃ to the primary winding of the pulse transformer PT, and the discharge current flows to the secondary side of the pulse transformer PT as shown in Fig. 4c.
The gate trigger signal for triac Q1 shown in Figure ₁ is generated. R ₂ and R ₃ are resistances. As a result, the triac _Q1 is turned on, and the capacitors _C1 and _C2 are discharged in a closed circuit formed by the primary winding a of the ballast B, the capacitors _C1 and _C2, and the triac _Q1 . At this time, the voltage applied to the primary winding a is the capacitor
It is the sum of the voltages of C ₁ and C ₂ and reaches the peak value of the AC power supply voltage V _S x 2 at maximum. This voltage is boosted to the secondary side of ballast B, producing a high voltage pulse across lamp _L1 (FIG. 4f). At this time, the capacitor C ₁ is charged by the AC power source V _S via the triax Q ₁ and the diode D ₂ , and is inverted as shown in FIG. 4d. The capacitor _C2 is immediately charged back to its original state via the primary winding a and the diode _D2 (Fig. 4e), and the triax _Q1
is turned off. On the other hand, when the S ₂ terminal of the AC power supply V _S is positive, the charging and discharging relationship of the capacitors C ₁ and C ₂ is reversed, but the charging and discharging relationship of the capacitors C ₁ and C ₂ when the triax Q ₁ is turned on is The direction is the same as in the previous case, so the direction of the high voltage pulses generated at both ends of the lamp _L1 is also the same. Also, when the lamp L ₁ lights up, the capacitor C ₃ of the trigger circuit T ₁
Since the voltage V _C3 of the switch element Q ₂ no longer reaches the response voltage V _Q2 of the switch element Q 2 , no pulse is generated. In other words, since the triax Q ₁ remains off, the capacitors C ₁ and C ₂ always remain charged, and no power loss occurs.

Because of this configuration, this embodiment has less pulse voltage fluctuations due to power supply fluctuations, eliminates power loss when pulses are stopped, and can increase pulse width and height at the same time. High-voltage pulses can be generated more easily.

A second embodiment of the invention is shown in FIG. In this embodiment, diodes D ₁ ′ and D ₂ ′ are connected so that the charging direction of each capacitor C ₁ and C ₂ is opposite to that of the first embodiment, and the other features are the same as in the first embodiment. be.

A third embodiment of the invention is shown in FIG. This uses a four-layer diode-thyristor with a control pole instead of the above-mentioned triax _Q1 , which is the switching means.
SCRs, Schottsley diodes, transistors, and other devices with polarity in the direction of current flow are used, and the connection direction is set by each diode D ₁ ,
In the closed circuit formed by D ₂ and the thyristor SCR, the three elements are connected to each other with the same polarity. In other words capacitor
C ₁ and C ₂ are connected in the direction of conduction in the discharge direction. The rest is the same as the first embodiment.

A discharge lamp lighting device to which a fourth embodiment of the present invention is applied is shown in FIG. In this case, _the primary end of the ballast B is connected to _the lamp L ₁ side, _and a voltage responsive switching element (SSS
etc.). In this case, after the lamp is turned on, pulse generation stops when the sum of the voltages of capacitors C ₁ and C ₂ becomes less than the response voltage of switch element Q ₃ . Therefore, there is an advantage that a trigger circuit is not required.

A discharge lamp lighting device to which a fifth embodiment of the present invention is applied is shown in FIG. This uses an auto-transformer B'' for pulse generation in addition to the ballast B'.
_C4 is a pulse bypass capacitor. In this case, a general type of ballast B' can be used, and there is no need to create a separate tap to separate the primary and secondary ballasts.

〔Effect of the invention〕

As described above, according to the starting pulse generator for a discharge lamp lighting device of the present invention, pulse fluctuations due to power supply voltage fluctuations are small, there is no power loss after the pulse stops, and high voltage pulses can be easily obtained. effective.

[Brief explanation of drawings]

1 and 2 are circuit diagrams of a conventional example, FIG. 3 is a discharge lamp lighting circuit diagram to which the first embodiment of the present invention is applied, FIG. 4 is a waveform diagram of each part, and FIG. 6 is a circuit diagram of the third embodiment, FIG. 7 is a discharge lamp lighting circuit diagram applying the fourth embodiment, and FIG. 8 is a circuit diagram of the fifth embodiment. It is a discharge lamp lighting circuit diagram. B...Ballast (autotransformer), B''...Autotransformer, a...Primary winding, _C1 , _C2 ...Capacitor (capacitance element), _D1 , _D1 ', _D2 , D ₂ ′...Diode (rectifier), L ₁ ...Discharge lamp (lamp), V _S ...
...AC power supply, Q ₁ ...Triack (switching means), SCR...Thyristor (switching means), Q ₃
...Voltage responsive switch element (switch means).

Claims (1)

[Scope of Claims] 1. A pair of circuits in which a capacitive element and a rectifying element are connected in series, and the rectifying elements are connected in opposite polarities to each other. and an autotransformer in which each capacitive element side of the second charging circuit is connected to both ends of the primary winding, and a secondary voltage of the secondary winding is applied to the discharge lamp;
a switch means connected between the connection points of the capacitive element and the rectifying element of the first and second charging circuits to conduct in the discharge direction of the capacitive element at a certain phase angle in each half cycle of the AC power source; A starting pulse generator for a discharge lamp lighting device in which each charging circuit is charged by the AC power source. 2. The starting pulse generator for a discharge lamp lighting device according to claim 1, wherein the single-turn transformer is a discharge lamp ballast. 3. The starting pulse generator for a discharge lamp lighting device according to claim 1, wherein the switch means is a voltage responsive switch element.