JPH0251896A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To prevent the reduction of pulse voltage with a simple structure by operating an igniter circuit by use of a DC power as supply the power supply of a discharge lamp lighting device. CONSTITUTION:A DC power supply being an INV power source is used as the power supply of an igniter circuit IGN. When a transistor is under ON operation, a condenser C1, resistor R2, transistor Q6, condenser C3, diode D2, transistor Q4, resistance Rs, and condenser C1 are charged in the above order. Further, when a transistor Q1 is under ON operation, a condenser C1, resistance R3, transistor Q1, condenser C2, diode D1, transistor Q3, resistance Rs, condenser C1 are charged in the above order. It is thus possible to generate high voltage pulses in an igniter circuit irrespective of the secondary voltage applied to the discharge lamp and to prevent the reduction of pulse voltage.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention provides a discharge lamp having a function of lighting the discharge lamp with a low-frequency rectangular wave and reducing the voltage applied to the discharge lamp when there is no load;
This relates to an alpha lamp device.

[Prior Art 1] A conventional discharge lamp lighting device is shown in FIG. This discharge lamp, α
The lighting device connects the commercial power supply VS with a diode bridge DB″c
9 and smoothed by a smoothing capacitor CL, the DC voltage obtained is applied to the transistors Q, ~Q<, and the control circuit 1 that controls the on/off of these transistors Q1 to Qi.
The inverter INV converts the voltage into an alternating current voltage and applies it to the discharge lamp DL, thereby lighting the discharge lamp DL. The control circuit 1 of this inverter INV detects the current flowing to the inverter rNV from the voltage across the resistor Rs, and controls the transistors Q, -Q according to this detected current.

The discharge lamp DL is connected to the connection point of the transistors Q, , Q, and the transistor Q2. Q is connected to α via a choke film, and a capacitor C2 is connected in parallel.

FIG. 4 is a timing chart showing the operation of transistors Q, ~Q, and as shown in (a) and (+3) in the same figure, transistors Q and -Q2 are high frequency, and (c) in the same figure,
As shown in (d), transistors Q, , Q, turn on and off at low frequencies. Then, the transistors Q,,Q, are alternately turned on and off, and the on period of the transistor Q, is l.
The transistor Q2 performs on/off operations during the on period of the transistor Q. Note that the duty ratio of transistors Q, Q2 is determined by the current detection resistor R.
It is varied by the control circuit 1 depending on the magnitude of the voltage across s.

Specifically, when transistor Q is turned on, capacitor C3, transistor Q choke coil L1, discharge lamp DL (capacitor C2L), transistor Q resistor Rs
, a closed circuit of capacitor C3 is formed. Also, when transistor Q2 is turned on, capacitor C is turned on. Transistor Q2, discharge lamp DL (capacitor C2), choke coil L7, transistor Q1, resistor R5,
1 m circuits are formed. Therefore, a rectangular wave alternating current (I[IL) including a high frequency γ pull shown in FIG. 4(e) flows through the discharge lamp DL.

By the way, the discharge lamp lighting device described above periodically applies high voltage pulses to the discharge lamp D1. The discharge lamp DL is provided with an igniter circuit IGN that applies a voltage to start the discharge lamp DL. This igniter circuit IGN includes a pulse transformer PT having a secondary winding connected in series with the discharge lamp DI-, and a resistor R0 connected in parallel to a series circuit of the discharge lamp DL and the primary 8M of the pulse transformer PT. It consists of a capacitor C3, a triac Q connected to both ends of the capacitor C2 via the primary winding of a pulse transformer PT, and a capacitor C4. , triac Q, is turned on, capacitor C3, triac 7
Q9, the capacitor C is suddenly discharged in the circuit of the primary winding of the pulse transformer PT, induces a high voltage pulse in the secondary winding of the pulse transformer PT, and this high voltage pulse is passed through the capacitor C2 to the discharge lamp DL. is applied to start the discharge lamp DL. 5(a) to (cl) show the secondary voltage VO2 applied to the discharge lamp DL and the voltage V e3 across the capacitor C1.
, voltage Ve across capacitor C4 triac Q,
The voltage across V. .

, and the voltage VO5 across the trier γri Q5 is the voltage Ve3 across the capacitor C1 and the voltage V across the capacitor C2.
The voltage difference is c4.

By the way, in this discharge lamp 1 lighting device, if the no-load state continues, such as when the discharge lamp DL is not attached, the two major voltages Vo2 will remain at a high voltage, which is not desirable for safety.

Therefore, in this discharge lamp 1g and lamp device, when the no-load state is detected by the current detection resistor Rs, as shown in Fig. 6 (
As shown in a) and (b), the transistor Q IjQ2
This is to stop the oscillation of , and to reduce the effective value of the two major voltages Vo2 during no-load. Note that this transistor Q,
, Q2 stop oscillating every time the transistors Q, , Q turn on, and the two large voltages Vo2 become as shown in FIG. 6(e).

When the no-load state is detected as shown in Fig. 6(e), the two major voltages Vo2 decrease after α(tl), as shown in Figs. 7(b) and (e). igniter circuit I
Since the voltage across the capacitors C, , C, of GN is also reduced, the peak value of the high voltage pulse generated in the igniter circuit IGN is reduced as shown in FIG. 7(a). By the way, in the control circuit 1 of this discharge lamp and alpha lamp device, the current detection resistor R
Since the no-load state is detected from the voltage across s, it is not possible to distinguish between a no-load state and a state close to a no-load state when the discharge lamp DL is not lit. As the two major voltages Vo2 decrease, the discharge lamp D
L.

There was a problem with the engine not being able to start.

Therefore, as shown in Figure 8, the resistor R and capacitor C
A rectangular wave power supply PS for charging the capacitor C1 is connected to both ends of the series circuit with the igniter circuit IGN.
It is possible to prevent #li from decreasing, but in this case, a rectangular wave power source with a complicated circuit configuration would be newly provided, which would lead to an increase in cost.

[Problem to be Solved by the Invention 1] The present invention has been made in view of the above points, and its purpose is to provide a discharge lamp lighting device that can prevent reduction in pulse voltage with a simple configuration. Our goal is to provide the following.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides two sets of series circuits each consisting of a high frequency switching element that switches at high frequency and a low frequency switching element that switches at low frequency at both ends of a DC power supply. A discharge lamp is connected to connecting point 1 of the switching elements of each series circuit, and the high-frequency switching element of one series circuit and the low-frequency switching element of the other series circuit are paired and driven alternately. do,
An inverter that converts the DC power supply voltage into a low-frequency rectangular wave voltage to light the discharge lamp, an igniter circuit that applies a high-voltage pulse to the discharge lamp to start it, and drive control of the switching elements of the α lamp circuit. and a control circuit that detects a no-load state from the inverter current, stops the high frequency switching element every half cycle period of the low frequency, and reduces the voltage applied to the discharge lamp, and the igniter circuit. The above DC power supply is used as a power source.

(Function) As described above, the present invention can be used as a power source for an igniter circuit.
By using the DC power source that powers the inverter,
By enabling the igniter circuit to generate high-voltage pulses regardless of the secondary voltage applied to the discharge lamp, preventing reduction in pulse voltage, and not requiring a separate power supply for the igniter circuit. , the circuit is not complicated and the cost does not increase.

(Embodiment) FIG. 1 shows an embodiment of the present invention. In this embodiment, a series circuit of a resistor R2, a transistor Q6, and a diode D is connected in parallel to the transistor Q1, and a resistor is connected in parallel to the transistor Q2. A series circuit of R5, transistor Q7, and diode D2 is connected, and a capacitor C2 is connected between the five connection points of transistor Q6 and diode D and the connection point of transistor Q7 and diode D2. Transistors Q, 1 transistor Q, and transistor Q7 are turned on and off in synchronization with transistor Q, respectively.

Now, if a no-load state is detected from the voltage across the resistor Rs, the control circuit 1 puts the transistor into the tranostor QQ2 state and reduces the two major voltages Vo2 as described above. However, in the discharge lamp lighting device of this embodiment, the transistors Q, , Q, which continue on-off operation at all times, and the transistors Q, , Q, which continuously turn on and off, and the transistors Q, , , Q, which operate on and off at all times. The capacitor C3 is charged by the transistors Q, , Q, which are connected to each other. That is, when transistor Q6 is on, capacitor C1, resistor R2, transistor Q6, capacitor C1, diode D2, transistor Q4, resistor Rs,
Capacitor C1 is charged in the path of capacitor CI, and transistor Q is on.
Resistor R1, transistor Q? , capacitor C3, diode D2, transistor Q0, resistor Rs.

Capacitor C3 is charged through the path of capacitor C1.

Therefore, even if the two major voltages Vo2 are reduced by turning off the transistors Q, , Q, the capacitor C3 is sufficiently charged by the voltage across the capacitor C3, so The peak value of the high-voltage pulse becomes low, and the inconvenience of not being able to light up the discharge lamp DL that is in the non-lighting state can be resolved.The transistors Q, ,Q
, is the transistor Q3. Since the on/off operation is performed in synchronization with Q, there is no need to provide a separate base drive circuit for these trannostars Q, ,Q.

By the way, in the present invention, the DC voltage obtained by rectifying the commercial power supply Vs shown in FIG. 2 is applied to the transistor Q. , diode D0, inductance I-aoz, and capacitor C0.
It can also be applied to a discharge lamp lighting device that converts the NV into AC voltage and lights the discharge lamp DL.

[Effect of the invention 1] As described above, in the present invention, the igniter circuit is operated using the DC power supply, so the igniter circuit can generate high voltage pulses regardless of the secondary voltage applied to the discharge lamp. Therefore, the pulse voltage does not decrease, and a separate power supply for the evening circuit is not required, so the circuit configuration does not become complicated and the cost does not increase.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of one embodiment of the present invention, Figure 2 is a circuit diagram of another embodiment, Figure 3 is a circuit diagram of a conventional example, Figure 4 is an explanatory diagram of the same operation, and Figure 5 is a circuit diagram of another embodiment. FIG. 6 is an explanatory diagram of the operation of the igniter circuit, FIG. 6 is an explanatory diagram of the operation under no load, FIG. 7 is an explanatory diagram of the operation of the igniter under no load, and FIG. 8 is a circuit diagram of the main part of another conventional example. 1 is a control circuit, INV is an inverter, IGN is an igniter circuit, DL is a discharge lamp, Q, ~Q are trannostars, R
s is resistance. Dai F! ! Person Patent Attorney Stone 1) Ai No. 7 4g Figure 1 Figure 2 To

Claims (1)

[Claims] (1) Two series circuits consisting of a high-frequency switching element that switches at high frequency and a low-frequency switching element that switches at low frequency are connected in parallel across both ends of a DC power supply, and air is released between the connection points of the switching elements of each series circuit. A lamp is connected, and the high-frequency switching element in one series circuit and the low-frequency switching element in the other series circuit are driven alternately to convert the DC power voltage into a low-frequency rectangular wave voltage and discharge it. an inverter that turns on the electric lamp; an igniter circuit that applies a high-voltage pulse to the discharge lamp to start it;
In addition to controlling the driving of the switching element of the lighting circuit, the no-load state is detected from the current of the inverter, and the high-frequency switching element is stopped every low-frequency half cycle period to reduce the voltage applied to the discharge lamp. 1. A discharge lamp lighting device comprising: a control circuit; and an igniter circuit operated using the DC power source as a power source.