JPH0328796B2 - - 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]

For discharge lamps that require high-voltage pulses for starting, we developed the first starting pulse generator that is less affected by power supply voltage fluctuations and eliminates power loss after the pulse stops.
What is proposed is shown in the figure. That is, V _S
is an AC power supply, B is a single-turn ballast that is a reactance element for current limiting, L is a discharge lamp, C ₁ is a capacitor that is the first capacitive element, C ₂ is a capacitor that is the second capacitive element, D ₁ is a diode which is a first rectifying element, _D2 is a diode which is a second rectifying element, Q is a triac which is a switching means, and T is a trigger circuit. The operation of this circuit is
When the S ₁ end of V _S (Figure 2a) is positive, capacitor C ₁ has been charged in the previous half cycle as shown in Figure 2c, and capacitor C ₂ has been charged as shown in Figure 2b. It will be charged. 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 . Here, when the triac Q, which is the switching means, is triggered and turned on at an arbitrary phase (Fig. 2 d), the capacitor
A closed circuit consisting of C ₁ , C ₂ and the primary winding a of ballast B is used to discharge the voltage of the series circuit of capacitors C ₁ and C ₂ . This voltage is boosted and transmitted to the secondary side of the ballast B, and a high voltage pulse is generated across the lamp L (FIG. 2e). Further, the capacitor _C1 is charged by the AC power supply V _S via the triax Q and the diode _D2 , and is inverted as shown in FIG. 2c. Also, the capacitor _C2 is immediately charged back to its original state via the primary winding a of the ballast B and the diode _D2 , and the triac Q is turned off. On the other hand, when the _S2 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 triack Q is turned on is The direction is the same as in the previous case, and therefore the direction of the high voltage pulses generated at both ends of the lamp L is also the same.

However, this starting pulse generator has a drawback that the heights h ₁ and h ₂ and the widths w ₁ and w ₂ of the output pulses differ depending on the positive and negative polarity of the AC power supply V _S and each half cycle, as shown in FIG. This means that when the capacitor _C1 is charged and the triax Q is turned on during the positive half cycle of the _S1 end of the AC power supply V _S , the capacitor _C1 is connected to the capacitor _C2 and the primary winding a of the ballast B.
The voltage applied to the primary winding a of the ballast B decreases because it is discharged through the AC power supply V _S , the capacitor C ₁ , the triax Q and the diode D ₂ in a closed loop and charged in the opposite direction. It happens. Also, at this time, as mentioned above, V _S →C ₁ →Q→
The current flowing through D ₂ is extremely large because the impedance of the AC power supply V _S is ideally 0, and as well as the power supply feedback noise increases, the peak current values of the triax Q and diode D ₂ increase, and the current capacity decreases. I had to use a larger one.

[Purpose of the invention]

Therefore, an object of the present invention is to provide a starting pulse generator for a discharge lamp lighting device that can generate stable pulses with less fluctuation, reduce power supply feedback noise, and reduce the current capacity of switching means and rectifying elements. The purpose is to provide equipment.

[Disclosure of the invention]

This invention includes an AC power source, a discharge lamp connected to the AC power source via a current-limiting reactance element connected to one end of the AC power source, and a first capacitive element on the reactance element side. A first charging circuit in which the first capacitive element and a first rectifying element are connected in series to both ends of the AC power supply, and a second capacitive element and a second rectifying element are connected in series. The second capacitive element is on the reactance element side, and the second rectifying element is on the first side.
a second charging circuit connected to both ends of the AC power source via a part of the reactance element so as to have a polarity opposite to that of the rectifying element; and a capacitive element and a rectifying element of the first and second charging circuits. and a series circuit of at least the first capacitive element, the switching means, and the second rectifying element. and an impedance element connected to both ends of the alternating current power source via the AC power source.

According to the configuration of the present invention, each time the switch means is turned on, the first capacitive element, the second capacitive element,
A closed circuit of a part of the reactance element is formed, so that the discharge voltage of the first capacitive element and the second capacitive element is applied to a part of the reactance element, which generates a discharge lamp starting pulse in the reactance element. do. On the other hand, when the switch means is turned on, the first capacitor element is reversely charged by a half cycle in the same direction as the second rectifier element of the AC power source through the series circuit of the first capacitor element, the switch means, and the second rectifier element. However, since an impedance element is connected to the series circuit, a decrease in the discharge voltage of the first capacitive element can be suppressed, and a decrease in the discharge voltage to the part of the reactance element can be suppressed. Therefore, compared to the conventional example, it is possible to suppress fluctuations in the output pulse every half cycle of the AC power supply and achieve stability. Further, the impedance element can reduce power supply feedback noise and reduce the current capacity of the element.

FIG. 4 shows a discharge lamp lighting device to which a first embodiment of the present invention is applied. That is, the difference from Fig. 1 is that a resistor R, which is an impedance element, is connected to the diode _D2 , which is the charging side when the capacitor _C1 is discharged.
is inserted in series. This resistor R allows the capacitor C ₁ to close when the S ₁ end of the AC power supply V _S is positive.
By reverse charging, the voltage applied to the primary winding a of ballast B is suppressed from decreasing, and when the _S2 terminal of the AC power supply V _S is positive, the voltage applied to the primary winding a of ballast B is It is possible to reduce the difference between the pulse width and the voltage value between the positive and negative half cycles. Furthermore, the resistor R reduces power supply feedback noise and further reduces the current capacity of the triac Q and diode _D2 .

A discharge lamp lighting device to which a second embodiment of the present invention is applied is shown in FIG. This is achieved by inserting resistors R ₁ and R ₂ in series with the diodes D ₁ and D ₂ of each charging circuit. As a result, the resistance R ₂ causes the AC power supply V _S
The capacitor C ₁ at the time of pulse generation when the S ₁ end is positive,
In addition to suppressing the reverse charging current flowing through the triax Q and the diode _D2 , the resistor _R1 suppresses the reverse charging current that flows when the _S2 terminal of the AC power supply V _S is positive when a pulse is generated.
By regulating the oscillating current flowing along the path V _S →D ₁ →C ₂ →a, it is possible to further reduce the difference in fluctuation between pulses than in the first embodiment.

A discharge lamp lighting device to which a third embodiment of the present invention is applied is shown in FIG. This is applied to a saturated vapor pressure type high pressure discharge lamp L ₁ , and the starting pulse generator I replaces the resistors R ₁ and R ₂ of the second embodiment with one resistor R _P
It is composed of. In the figure, P is a phase control type fixed tube voltage control circuit, which incorporates a pulse transformer _PT2 for triggering the triax Q. Also, while synchronizing with the voltage on the AC power supply side,
The tube voltage of the discharge lamp _L1 on the load side of the inductance element _L2 is detected, and an integrated circuit IC detects the pulse transformer for triggering the triac _Q1 according to the fluctuation of the tube voltage.
By changing the pulse generation point of PT ₁ , try-out is possible.
By changing the phase angle of _Q1 , the tube voltage is always kept constant, and the color temperature of the discharge lamp _L1 is kept constant. T is a step-down transformer,
DB ₁ , DB ₂ are rectifiers, D ₁ to D ₁₀ , D _g1 are diodes, Z ₁ to _{Z 5} are Zener diodes, C ₁ to _{C 9} , C _S ,
C _N is a capacitor, Q ₁ to Q ₆ are transistors, R ₁ to
R ₁₆ , R _S , R _a to R _c , R _g1 , and R _g2 are resistors, and ZNR is a voltage responsive element.

A discharge lamp lighting device to which a fourth embodiment of the present invention is applied is shown in FIG. In comparison with Fig. 1, this means that the _S1 end of the AC power supply V _S is connected to the midpoint N including the midpoint of the primary winding a, and the primary winding a is connected to each charging circuit.
The structure is such that the inductances DL ₁ and DL ₂ are inserted. Thereby, the pulses generated in each half cycle can be made equal, and it is possible to prevent the voltage reduction of the capacitor _C1 when pulses are generated as in the conventional case.

In addition, in this invention, a single-turn transformer separate from the ballast may be used. Further, the switch means is not limited to a triax, and may have any configuration as long as it is turned on at a certain phase angle every half cycle of the AC power supply.

〔Effect of the invention〕

As described above, according to the starting pulse generator for a discharge lamp lighting device of the present invention, the width and voltage value of the generated pulse can be stabilized, power supply feedback noise can be reduced, and the current capacity of the switching means and rectifying element can be reduced. It has the effect of being able to be made smaller.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of a conventional example, Figure 2 is a waveform diagram of each part, Figure 3 is a detailed waveform diagram of generated pulses, and Figure 4 is a diagram of a detailed waveform of generated pulses.
The figure is a discharge lamp lighting circuit diagram to which the first embodiment of the present invention is applied, FIG. 5 is a discharge lamp lighting circuit diagram to which the second embodiment is applied, and FIG. 6 is a discharge lamp lighting circuit diagram to which the third embodiment is applied. Lamp Lighting Circuit Diagram FIG. 7 is a discharge lamp lighting circuit diagram to which the fourth embodiment is applied. B...Single-turn ballast that is a reactance element for current limiting, L, _L1 ...Discharge lamp, _C1 ...Capacitor that is the first capacitive element, _C2 ...Capacitor that is the second capacitive element , D ₁ ...Diode which is the first rectifying element, D ₂ ... Diode which is the second rectifying element, Q... Triax which is the switching means, V _S ... AC power supply, R, R ₂ , R _p ...Resistance is an impedance element.

Claims (1)

[Claims] 1. An AC power source, a discharge lamp connected to the AC power source via a current-limiting reactance element connected to one end of the AC power source, and a first capacitive element connected to the reactance element side. A first charging circuit in which the first capacitive element and a first rectifying element are connected in series to both ends of the AC power supply, and a second capacitive element and a second rectifying element are connected in series. and the second capacitive element is on the reactance element side, and the second rectifying element is connected to both ends of the AC power supply via a part of the reactance element so that the polarity is opposite to that of the first rectifying element. a switch means connected between a connected second charging circuit and a connection point between a capacitive element and a rectifying element of the first and second charging circuits and conductive at a predetermined phase of each half cycle of the AC power supply; and an impedance element connected to both ends of the AC power source via a series circuit of at least the first capacitive element, the switching means, and the second rectifying element. Generator. 2. The starting pulse generator for a discharge lamp lighting device according to claim 1, wherein the impedance element is a resistor connected in series to the second rectifying element of the second charging circuit. 3. The impedance element is an inductance connected in series to the first capacitive element of the first charging circuit by connecting one end of the AC power source to an intermediate point of the part of the reactance element. A starting pulse generator for a discharge lamp lighting device according to claim 1.