JPS6054760B2 - discharge lamp lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises an AC power source 1, a series circuit of an inductance element 2, a capacitor 3, and a switch element 4 to form a first closed circuit. A second closed circuit is constituted by the current limiting element 5, which includes at least one of the elements 3 and composed of only an inductance element or an inductance element and a capacitor element, and the discharge lamp 6, and the voltage VAC of the AC power supply 1 is The voltage is set to maintain the lighting of the discharge lamp 6, and the switching element 4 is controlled to be turned on and off once every half cycle of the AC power source 1 with an appropriate phase, and the first closing is performed by the operation of the switching element 4. This invention relates to a discharge lamp lighting device characterized in that a state in which a resonant voltage generated in a circuit is applied to the discharge lamp 6 is full lighting, and an on state in which the on/off operation of the switch element 4 is stopped is controlled lighting. The purpose is to provide a compact and lightweight discharge lamp lighting device that can dim the discharge lamp.

Figures 1 to 4 show the circuits of conventional discharge lamp lighting devices capable of dimming. The device in FIG. 3 adjusts the light by changing the applied voltage itself by turning on or off the switch 7, and the device in FIG. ' is connected in series to the input circuit to dim the input, and the discharge lamp 6
This is a continuous dimming method in which a pulse voltage is applied to both ends by a pulse generating circuit 8'.

However, these conventional devices have disadvantages in that it is difficult to downsize the current limiting element 5, and the current limiting element 5 is large and heavy. The present invention has been provided in view of the above-mentioned problems, and will be described below with reference to Examples.

FIG. 5 shows a basic circuit diagram of the present invention, in which a series circuit of an inductance element 2, a capacitor 3, and a switch element 4 is connected to an AC power supply 1 to form a first closed circuit, and a switch element A discharge lamp 6 is connected in parallel to the AC power source 1, a current-limiting element 5 formed from an inductance element 2, a capacitor 3, and the discharge lamp 6 to form a second closed circuit. Reference numeral 9 denotes a control circuit for the switch element 4, and this control circuit 9 turns the switch element 4 on and off once in a half cycle of the AC power source 1 at appropriate phases.

Further, the voltage VAO of the AC power source 1 is set to a voltage sufficient to keep the discharge lamp 6 lit. FIG. 6 shows a time chart of each lamp in the basic circuit of FIG.
The figure b shows the input current 11, the figure C shows the voltage across the capacitor 3, the figure d shows the current 14 flowing to the switch element 4, and the figure e
indicates the lamp voltage Vll, and f indicates the lamp current 11a, respectively. Now, if switch element 4 is made conductive at the moment of ignition,
Inductance element 2, capacitor 3, switch element 4
A series resonant circuit is formed by the series circuit of , a larger current 11 flows through the current limiting element 5 than when the switching element 4 is off, and a larger amount of charge is accumulated in the capacitor 3. Next, when the switch element 4 is turned off at the moment when the current 14 flowing through the switch element 4 is about to reverse to negative, the voltage accumulated in the capacitor 3 is applied to the discharge lamp 6, and at the same time the discharge lamp 6 is re-ignited, the capacitor is turned off. 3 and the energy supplied from the AC power source 1 through the current limiting element 5, the lamp current 1 is larger than when the switch element 4 is always off.
1a will flow. Thereafter, at time t1 again, the switch element 4 is turned on again, the discharge lamp 6 is short-circuited by the switch element 4, and the lamp voltage Vla and the lamp current 11a
Both become zero, and a series resonant circuit of the inductance element 2, the capacitor 3, and the switch element 4 is formed through the switch element 4. Such an operation is repeated every half cycle, and the discharge lamp 6 is maintained in a fully lit state. On the other hand, when the output of the control signal S of the control circuit 9 is stopped to stop the operation of the switch element 4 and the switch element 4 is set to the OFF state, the lamp current Ila is changed from the AC power supply 1 to
The discharge lamp 6 is turned on with a smaller current than when the switch element 4 is operated, which is determined by the current-limiting element 5, and the discharge lamp 6 is in a dimming state. By the way, in the case of such a basic circuit, in a fully lit state, a first closed circuit including an AC power source 1, an inductance element 2, a capacitor 3, and a switch element 4 includes an inductance element 2, a capacitor 3, and a switch element 4.
On/off phase of AC power supply 1, current limiting element 5, discharge lamp 6
However, at the time of dimming, it is determined only by the impedance of the second closed circuit, so there is no freedom in setting the dimming state. There is a problem with L. In addition, the solid waveform line in FIG. 6 indicates the time of full lighting, and the wavy line indicates the time of dimming. The present invention relates to a discharge lamp lighting device in which the dimming state can be freely set, and FIG. 7 shows an embodiment of the circuit. In this embodiment circuit, a discharge lamp 6 is connected in parallel to a series circuit of a capacitor 3 and a switch element 4 through a capacitor 10, and a current-limiting element 5 is formed by the inductance element 2 and the capacitor 10. In this example circuit, when all lights are on, the first closed circuit (the series circuit of the AC power source 1, the inductance element 2, the capacitor 3, and the switch element 4) is connected by the on/off operation of the switch element 4 of the basic circuit described above. A large resonant voltage generated in a closed circuit (formed by a closed circuit formed by Set to . That is, as shown in FIG. 8, when dimming, a vector diagram is drawn, and the light is turned on only with the energy supplied from the AC power source 1, resulting in a dimming state. The energy from the AC power supply 1 is then divided into a current flowing through the capacitor 3 and a current flowing through the capacitor 10. Therefore, the energy flows through the first closed circuit and the second circuit consisting of the current limiting element 5 and the discharge lamp 6.
The degree of dimming can be determined by the combined impedance of all the impedance elements with the closed circuit. In FIG. 8, Vll represents the lamp voltage, Vc and O represent the voltage of the capacitor 10, VO represents the voltage of the capacitor 3, and VCh2 represents the voltage of the inductance element 2. VAO represents the voltage of the AC power supply 1. FIG. 9 shows another embodiment of the invention, in which capacitor 3
Then, the positions of the inductance element 2 and the inductance element 2 are reversed in the circuit shown in FIG. The current-limiting element 5 is composed of the following elements, and a vector diagram as shown in FIG. 10 is drawn during dimming. VChl in Figure 10
l indicates the voltage of the inductance element 11. FIG. 11 shows another embodiment circuit in which a discharge lamp 6 is connected in parallel to a series circuit of a capacitor 3 and a switch element 4, and a current limiting element 5 is formed only by an inductance element 2. , At the time of dimming, a vector diagram as shown in FIG. 12 is drawn. The voltage VAC of the AC power source 1 is set to VAO>Vll so as to sufficiently keep the discharge lamp 6 lit. The present invention is configured as described above, and the voltage of the AC power source is set to a voltage that can maintain lighting of the discharge lamp, and the above-mentioned switch element is controlled to be turned on and off at an appropriate phase once every half cycle of the AC power source. , full lighting is achieved by applying the resonant voltage generated in the first closed circuit due to the operation of the switch element to the discharge lamp, and by keeping the switch element in a continuous ON state, only the energy of the AC power source is used. The discharge lamp can be turned on, and as a result, the energy applied to the discharge lamp is smaller than when applying a resonant voltage, and dimming can be performed.Moreover, the degree of dimming can be controlled by the first closed circuit and the second closed circuit. Since the combined impedance of the discharge lamp can be determined by the composite impedance of Since it can be determined by the composite impedance of all the impedance elements of the closed circuit and the second closed circuit, the dimming state can be set freely.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 4 are circuit configuration diagrams of the conventional example, FIG. 5 is a basic circuit configuration diagram of the present invention, FIG. 6 is a time chart of the same, and FIG. 7 is a diagram of the basic circuit configuration of the present invention. A circuit configuration diagram of one embodiment, FIG. 8 is a vector diagram of each part same as above, FIG. 9 is a circuit diagram of another embodiment of the present invention, FIG. 10 is a vector diagram of each part same as above, and FIG. 11 is a vector diagram of each part same as above. A circuit configuration diagram of another embodiment of the present invention, and FIG. 12 is a vector diagram of each part same as above, where 1 is an AC power supply, 2 is an inductance element, 3 is a capacitor, 4 is a switch element, and 5 is a current limiting element. , 6 is a discharge lamp, VA
C is the power supply voltage.

Claims (1)

[Claims] 1 A first closed circuit is configured by an AC power source and a series circuit such as an inductance element, a capacitor, and a switch, and also includes at least one of the AC power source and an inductance element and a capacitor, and includes only an inductance element or an inductance element and a capacitor. The discharge lamp and the current-limiting element constitute a second closed circuit, and the voltage of the AC power source is set to a voltage that can maintain lighting of the discharge lamp, and the switch element is connected to the voltage of the AC power source. On/off control is performed once every half cycle with an appropriate phase, and the state where the resonant voltage generated in the first closed circuit due to the operation of the switch element is applied to the discharge lamp is fully lit, and the on/off operation of the switch element is controlled. A discharge lamp lighting device characterized in that a stopped ON state is turned on as dimmed lighting.