JP3291853B2 - Discharge lamp lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device for lighting a discharge lamp at a high frequency, and more particularly to turning off a discharge lamp.

[0002]

2. Description of the Related Art FIG. 7 shows a circuit diagram of a conventional discharge lamp lighting device. The output of the DC power supply circuit 1 includes transistors Q ₁ ,
Series circuit of Q ₂ are connected. Diodes D ₁ and D ₂ are connected to both ends of each transistor Q ₁ and Q ₂ , respectively.
Are connected in anti-parallel. The collector of the transistor Q ₁ is, is connected to one end of the discharge lamp 2 via the capacitor C _2, the other end of the discharge lamp 2, the transistor Q ₁ through a primary winding of the inductor L ₁ and the current transformer CT Connected to the emitter. Between the non-power side of the discharge lamp 2 filament terminal, the capacitor C ₁ is connected in parallel. The secondary windings n ₁ and n ₂ of the current transformer CT are connected between the base and the emitter of the transistors Q ₁ and Q ₂ via the resistors R ₁ and R ₂ .

[0003] between the base and the emitter of the transistor Q _2, the transistor Q ₃ are connected in parallel. The base of the transistor Q ₃ is pulled up to the level of the DC power supply 5 by the resistor R _3, and is pulled down to the ground level when the open collector output of the comparator 3 becomes conductive. A duty-variable control signal is input from the control signal source 4 to the negative input terminal of the comparator 3. The voltage of the capacitor C ₆ charged by the resistor R ₆ is input to the positive input terminal of the comparator 3. The both ends of the capacitor C _6, the collector and emitter of the transistor Q ₄ is connected. The base of transistor Q ₄ are being pulled up to the level of the DC power source 5 by a resistor R _4, between the base and emitter of the transistor Q ₄ are, the transistor Q ₅ is connected. Between the base and emitter of the transistor Q ₅ is connected via a resistor R ₅ is the secondary winding n ₂ of the current transformer CT are connected.

[0004] A self-excited self-excited series inverter shown in FIG.
In the circuit, as shown in FIG.₁
And Q_TwoIs applied to the discharge lamp 2 when the ON times of
The voltage is shown in FIG.₁become that way. At this time,
Capacitor C_TwoThe DC component shared by
2. Diode D₁, D_Two, Transistor Q₁,
Q_TwoThe series inverter circuit composed of
Secondary winding n ₁, N_TwoTransit supplied by
Star Q₁, Q_TwoSelf-oscillates with the base current of
DC power from the power supply circuit 1 is converted into high-frequency power.
The power converted to the high frequency is a capacitor C₁And Indac
L₁And the discharge lamp 2 is turned on.

[0005] Next, when the ON time of the transistor Q ₁ is greater than the ON time of the transistor Q ₂ is, e of FIG. 9
It becomes like ₁ and becomes smaller than the case of FIG. At this time, the DC component shared by the capacitor C ₂ is E / 2
Smaller. And ON time of the transistor Q _2, the relationship between the DC voltage capacitor C ₂ is sharing changes as shown in FIG. 10. In other words, the ratio of the ON time of the transistor Q _1, the ON time of the transistor Q _2, the amount of the AC component as a supply energy to the discharge lamp 2 becomes controllable, is the enabling of dimming the discharge lamp 2. As described above, the dimming of the discharge lamp can be performed by changing the duty ratio of the inverter circuit.
No. 3716 and JP-A-60-113717.

The transistor Q in the circuit of FIG.₁~ Q
_FiveOperation and the capacitor C₆Voltage Vc₆Figure 1 shows the relationship
3 is shown. Transistor Q₁Is in the section where
Secondary winding n of the transformer CT_TwoBy transistor
Q_Two, Q_FiveIs pulled out, the transistor Q
_Two, Q_FiveBecomes OFF. Transistor Q_FiveOFF
Transistor Q_FourTurns ON and the capacitor C₆of
Pull out the charge. As a result, the positive input of the comparator 3 becomes
Because it is lower than the dimming signal voltage of the negative input, the transistor
Q_ThreeIs turned off. Next, self-excited oscillation
Transistor Q₁Is turned off, the current transformer CT
Secondary winding n_TwoAs a result, the transistor Q _Two, Q_FiveNibe
Current is supplied to the transistor Q_Two, Q_FiveIs ON
You. Also, the transistor Q_FiveIs turned on, Transis
TA Q_FourTurns off and the capacitor C₆Charging starts
You. Here, the capacitor C₆Voltage reaches the dimming signal voltage
When it reaches, transistor Q_ThreeTurns ON and the transistor Q
_TwoBy extracting the base current of
_TwoIs forcibly turned off. Repeat this series of operations.
And the transistor Q₁, Q_TwoIs a constant duty ratio
To repeat ON / OFF alternately. The dimming signal voltage
Of the capacitor C by changing the level of ₆No electricity
The time for the pressure to reach the dimming signal voltage level changes,
Transistor Q_TwoON time, that is, the inverter circuit
The duty ratio of the switching operation can be controlled. Dimming signal
Voltage and transistor Q_TwoON time, dimming signal voltage and dimming
The relationship between the luminous intensity is shown in FIGS.

In FIGS. 11 and 12, it is assumed that the dimming of the discharge lamp occurs when the dimming signal voltage is lowered to the level of V ₁ and the dimming of the discharge lamp is performed. A method of applying a pulse voltage as a means for maintaining stable lighting of the discharge lamp in such a deep dimming state will be described. In this method, in order to apply a high-voltage pulse to the discharge lamp in a deep dimming state, the on-duty of the switching element of the inverter circuit is periodically changed to such an extent that a high-voltage pulse can be applied to the discharge lamp. It is.

More specifically, referring to FIG. 14, a signal for periodically generating a pulsed voltage as shown in FIG. 14A is given as a dimming signal voltage. Accordingly, the duty of the inverter circuit changes according to the dimming signal voltage, and periodically provides high energy to the discharge lamp. If the cycle of applying the pulse voltage is set relatively long with respect to the oscillation frequency of the inverter, the voltage Va across the discharge lamp becomes as shown in FIG.
It changes as shown in FIG. By periodically applying a high voltage to both ends of the discharge lamp, a discharge path of the discharge lamp is secured, and a stable lighting state without flickering or flickering can be maintained even in a deep dimming state.

As a means for turning off the discharge lamp in a state where the pulsed voltage is applied to the discharge lamp, the dimming signal voltage is stopped, and as shown in FIG. 15, both the inverter and the pulse voltage are stopped. Means are used. However, since the light-off means stops the inverter, when the light is turned on again from the light-off state, it is necessary to restart the inverter and perform preheating again. For this reason, there is a problem that the transition from turning off to relighting cannot be performed smoothly.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned point, and an object of the present invention is to apply a pulsed voltage periodically in a low luminous flux lighting state. In a discharge lamp lighting device, a discharge lamp in a low luminous flux lighting state is turned off without stopping an inverter circuit, so that a transition from an off state to a relighting state can be smoothly performed.

[0011]

According to the present invention, in order to solve the above-mentioned problems, a stable low luminous flux lighting is achieved by periodically applying a high voltage to both ends of a discharge lamp which is lit at a high frequency. In a discharge lamp lighting device provided with a means for maintaining the high frequency, the high frequency applied to both ends of the discharge lamp is stopped.
And a means for turning off the discharge lamp by stopping the periodic application of a high voltage to the discharge lamp. Also, the fade-out of the discharge lamp should be performed by gradually lowering the peak value of the high voltage periodically applied to the discharge lamp or gradually increasing the application period of the high voltage periodically applied to the discharge lamp. Is also possible.

[0012]

According to the present invention, there is provided an apparatus for applying a high frequency to both ends of a discharge lamp and periodically applying a high voltage to keep the discharge lamp lit with a low luminous flux.
Without stopping the high frequency applied to the discharge lamp,
Since the discharge lamp is turned off by stopping the application of the periodic high voltage, there is no need to stop the inverter circuit, and therefore, the transition from the light-off state to the relighting can be smoothly performed. .

[0013]

FIG. 1 is a diagram for explaining the operation of a first embodiment of the present invention.
And shows the relationship between the dimming signal voltage and the lamp voltage Va.
You. In this embodiment, in the circuit of FIG.₁
When the dimming signal voltage (low luminous flux lighting state) is applied,
It is impossible to keep the light on, and it will go out.
You. Now, level V₁To the level V _Twoof
Lighting of low luminous flux of discharge lamp by applying pulsed dimming signal voltage
Stops the pulse-like dimming signal voltage when maintaining
Then, the discharge lamp is turned off. At this time, dimming
Signal voltage is level V₁Discharge lamp is turned off.
Even after lighting, the inverter circuit will continue to oscillate.
You.

FIG. 2 is a diagram for explaining the operation of the second embodiment of the present invention. In the present embodiment, instead of suddenly stopping the pulse-like dimming signal voltage as in the embodiment of FIG.
As shown in (1), the level of the pulse-like dimming signal voltage is gradually reduced. Thus, the discharge lamp can be faded out without turning off the oscillation of the inverter circuit.

FIG. 3 is a diagram for explaining the operation of the third embodiment of the present invention. In this embodiment, as shown in FIG. 3, the discharge lamp is faded out by gradually increasing the period of applying the pulsed dimming signal voltage. Thus, there is no need to stop the inverter, and the inverter circuit continues to oscillate even after the discharge lamp is turned off.

FIG. 4 is a circuit diagram of a fourth embodiment of the present invention. In this embodiment, a single-stone inverter circuit is used. The output of the DC power supply circuit 1 includes a transistor to Q ₁ for switching, the capacitor C _1, is converted into a high frequency by the single-transistor type inverter consists of inductor L _1.
Furthermore, resonates by the primary winding and the capacitor C ₃ of the current transformer CT, to light the discharge lamp 2 connected in parallel to the capacitor C _3. Here, the switching element Q
The base current of ₁ is the secondary winding n of the current transformer CT.
Supplied by _one . Further, the control circuit 6 pull the base current of the transistor Q ₁ turns on the transistor Q ₃ in response to the voltage from the dimming signal source 4, changing the ON / OFF duty of the transistor Q _1. As a result, the duty ratio of the output of the inverter changes, and the dimming of the discharge lamp can be performed. It is needless to say that the same light-off control can be performed in this single-type inverter circuit by changing the dimming signal voltage as shown in FIGS. As described above, the present invention is not limited to the inverter circuit system or the control system, and may be anything that performs control for changing the voltage Va across the discharge lamp as shown in FIGS.

FIG. 5 is a circuit diagram of a fifth embodiment of the present invention. In this embodiment, a pulsed voltage superimposing means 8 is added to both ends of the discharge lamp 2 connected to the discharge lamp lighting device 7, and the discharge lamp applied from the discharge lamp lighting device 7 at the time of low luminous flux lighting. The pulsed voltage is periodically superimposed on the basic amplitude of 2 to stably maintain the low luminous flux of the discharge lamp. FIG. 6 shows a voltage waveform applied by the pulsed voltage superimposing means 8 and a waveform of the voltage Va across the discharge lamp 2. Also in the discharge lamp lighting device provided with the low luminous flux lighting maintaining means based on the pulsed voltage superimposition method, the same extinguishing is performed by controlling the superimposed pulsed voltage to give the same change as in FIGS. Control can be performed.

[0018]

According to the present invention, in the discharge lamp lighting apparatus having a means for maintaining a stable low light flux lighting by applying a periodically high voltage across the discharge lamp to be lighted at a high frequency, release Stop the high frequency applied to both ends of the lamp
Without turning off the discharge lamp, periodic application of high voltage to the discharge lamp is stopped to turn off the discharge lamp. Therefore, when turning off the discharge lamp, there is no need to stop the inverter circuit, and the light is turned off. Thus, there is an effect that relighting can be easily performed.

[Brief description of the drawings]

FIG. 1 is an operation waveform diagram of a first embodiment of the present invention.

FIG. 2 is an operation waveform diagram of a second embodiment of the present invention.

FIG. 3 is an operation waveform diagram of a third embodiment of the present invention.

FIG. 4 is a circuit diagram of a fourth embodiment of the present invention.

FIG. 5 is a circuit diagram of a fifth embodiment of the present invention.

FIG. 6 is an operation waveform diagram according to a fifth embodiment of the present invention.

FIG. 7 is a circuit diagram of a conventional example.

FIG. 8 is a waveform chart showing a switching operation at the time of steady lighting of the conventional example.

FIG. 9 is a waveform diagram showing a switching operation at the time of dimming lighting in a conventional example.

FIG. 10 is an explanatory diagram of an operation at the time of steady lighting in a conventional example.

FIG. 11 is an explanatory diagram of an operation at the time of dimming lighting in a conventional example.

FIG. 12 is a diagram showing dimming characteristics of a conventional example.

FIG. 13 is a waveform chart showing the operation of each unit in the conventional example.

FIG. 14 is a waveform chart showing the operation of a conventional low luminous flux lighting maintaining means.

FIG. 15 is a waveform chart showing the operation of the conventional low luminous flux lighting and maintaining means when the light is turned off.

[Explanation of symbols]

 Reference Signs List 1 DC power supply circuit 2 Discharge lamp 3 Comparator 4 Control signal source 5 DC power supply for control

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-217894 (JP, A) JP-A-1-2177893 (JP, A) JP-A-1-217895 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H05B 41/24

Claims (3)

(57) [Claims] 1. A discharge lamp lighting apparatus having a means for maintaining a stable low light flux lighting by applying a periodically high voltage across the discharge lamp to be lit by a high frequency discharge
Without stopping the high frequency applied to both ends of the lamp,
A discharge lamp lighting device comprising means for turning off a discharge lamp by stopping periodic application of a high voltage to an electric lamp. 2. A discharge lamp lighting apparatus having a means for maintaining a stable low light flux lighting by applying a periodically high voltage across the discharge lamp to be lit by a high frequency discharge
Without stopping the high frequency applied to both ends of the lamp, a means for fading out the discharge lamp by gradually lowering the peak value of the high voltage periodically applied to the discharge lamp is provided. Discharge lamp lighting device. 3. The discharge lamp lighting apparatus having a means for maintaining a stable low light flux lighting by applying a periodically high voltage across the discharge lamp to be lit by a high frequency discharge
The discharge lamp is provided with means for fading out the discharge lamp by gradually increasing the application period of the high voltage periodically applied to the discharge lamp without stopping the high frequency applied to both ends of the lamp. Lighting device.