JPS6316879B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge lamp lighting device that lights a discharge lamp using high frequency and is dimmable.

The AC power supply is controlled by phase control, etc., and the output is full-wave rectified, and the DC voltage is input to the inverter, and a discharge lamp such as a fluorescent lamp is lit at a high frequency of 2 to 3 KHz or higher using the inverter, and Attempts have been made in the past to perform light control by changing the phase angle because it provides good light control with less flicker. Conventionally, it is the first such device.
The device shown in the figure is known.

In FIG. 1, reference numeral 1 denotes an AC power supply, and 2 a dimming device for controlling the phase of the voltage of the AC power supply 1, which is comprised of a bidirectional thyristor 3 and a control device 4 for controlling its conduction start phase.

Further, 6 is an inverter, which here is constituted by a push-pull type transistor inverter having a resonant circuit, and its input is a DC voltage obtained by rectifying the output of the dimmer 2 by a full-wave rectifier 5. 7 is a discharge lamp having preheating electrodes 7f ₁ and 7f ₂ such as a fluorescent lamp.

Inverter 6 has output winding 8s and collector winding 8
c ₁ , 8c ₂ , a base feedback winding 8b, and a flight winding 8f ₁ , 8f ₂ , an output transformer 8 consisting of a leakage transformer, switching transistors 9a, 9b, a high frequency choke coil 10, a resonant capacitor 11, It is composed of bias resistors 12a, 12b, etc.

That is, the connection point with the collector windings 8c ₁ and 8c ₂ is connected to the positive output end of the full-wave rectifier 5. The positive output end of the full-wave rectifier 5 is also connected to the bases of switching transistors 9a and 9b via bias resistors 12a and 12b, respectively. One end of each of the collector windings 8c ₁ and 8c ₂ is connected to the collectors of switching transistors 9a and 9b, respectively. The emitters of switching transistors 9a and 9b are respectively connected to both ends of base feedback winding 8b. A resonant capacitor 11 is connected between each end of the collector windings 8c ₁ and 8c ₂ .
is connected. switching transistor 9
Both emitters a and 9b are high frequency choke coil 1
0 to the negative output terminal of the full-wave rectifier 5. Thus, the inverter 6 is formed by the output transformer 8, the switching transistors 9a and 9b, the high frequency choke coil 10, the resonant capacitor 11, and the bias resistors 12a and 12b.

In addition, the filament winding 8 of the output transformer 8
f ₁ and 8f ₂ are connected to preheating electrodes 7f ₁ and 7f ₂ of the discharge lamp 7. As this discharge lamp 7, for example,
Fluorescent lights are used.

The output transformer 8 is also provided with an auxiliary winding 8k, and both ends of the auxiliary winding 8k are connected to a rectifier circuit 14.
is connected to the input end of the A capacitor 16 is connected between the positive and negative output terminals of the rectifier circuit 14, and the positive output terminal is connected to the positive output terminal of the full-wave rectifier 5 via a diode 15. There is. The negative output terminal of the full-wave rectifier 5 and the negative output terminal of the rectifier circuit 14 are connected in common. Thus, the auxiliary winding 8k, the rectifier circuit 14, the diode 15, and the capacitor 16 constitute an auxiliary DC power source.

In the apparatus configured as described above, when the AC power supply 1 is turned on, a full-wave rectified voltage is generated at the output end of the full-wave rectifier 5 as shown in FIG. 2a. When the bidirectional thyristor 3 sets its conduction start phase to a phase _of θ ₁ as shown in FIG. is supplied. Bias resistors 12a and 1 are connected to the bases of the switching transistors 9a and 9b of the inverter 6 for a period of time _T1 .
2b, the base feedback winding 8b performs self-oscillation as is well known, and a high frequency voltage is generated in each winding of the output transformer 8, and the filament windings 8f ₁ and 8f ₂ generate a preheating electrode 7f. _{1,7f 2}
, and the discharge lamp 7 is turned on.

Further, the degree of dimming is performed by changing the conduction start phase θ ₁ by the dimming device 2.

During the period T ₂ , DC power is not supplied from the dimmer 2 to the inverter 6, so during the period T ₁ when DC power is supplied from the dimmer 2, the auxiliary winding 8
The voltage of k is passed through the rectifier circuit 14 to the capacitor 16.
is charged and its terminal voltage Vcp is supplied to the input of the inverter 6 during the period _T2 , and the input voltage of the inverter 6 becomes as shown in FIG. 2b.

Since the terminal voltage Vcp of the capacitor 16 is set so that the discharge lamp 7 is turned off during the period _T2 when the voltage of the capacitor 16 is applied to the inverter 6, the discharge lamp 7 is turned off and the discharge lamp 7 is turned off. The preheating electrodes 7f ₁ , 7f ₂ are preheated by the filament windings 8f ₁ , 8f ₂ , and the preheating voltage is as shown in FIG. 2d. Note that FIG. 2c shows the discharge current of the discharge lamp 7.

As described above, the terminal voltage of the capacitor 16 is
By appropriately setting Vcp and capacity, it is possible to preheat the preheating electrodes 7f ₁ and 7f ₂ even during the period when the discharge current is not in use. This is intended to suppress deterioration of the electrodes and extend the life of the discharge lamp 7.

However, in such a conventional device, when the DC voltage from the dimmer 2 becomes low and the input voltage of the inverter 6 reaches the voltage of the capacitor 16, the voltage of the capacitor 16 increases due to fluctuations in the AC power supply 1. If the height is too high, the discharge of the discharge lamp 7 tends to continue without stopping.

If the discharge continues, not only will dimming not be performed smoothly, but the charge in the capacitor 16 will be rapidly discharged, and the terminal voltage will drop rapidly, making it difficult to sufficiently preheat the preheating electrodes 7f ₁ and 7f ₂ . I become unable to do it.

Furthermore, if the voltage of the capacitor 16 is set low to prevent the discharge from continuing, the input voltage of the inverter 6 will drop, and the voltage of the filament windings 8f ₁ and 8f ₂ will drop, allowing sufficient preheating of the preheating electrodes 7f ₁ and 7f ₂ . I find myself unable to do anything.

Furthermore, since the capacitor 16 requires a large-capacity electrolytic capacitor, the lighting device tends to be large, and the life of the electrolytic capacitor tends to be shortened.

The present invention eliminates the above-mentioned conventional drawbacks and provides a discharge lamp lighting device that can perform smooth dimming by sufficiently preheating the inverter during the period when DC power is supplied from the dimming device. The purpose is to provide

Embodiments of the discharge lamp lighting device of the present invention will be described below with reference to the drawings. FIG. 3 is a circuit diagram showing the configuration of one embodiment. In order to avoid duplication in the figure, the same parts as those in FIG. I will focus on the different parts.

In FIG. 3, an AC power supply 1, a dimmer 2, a bidirectional thyristor 3, a control device 4, a full-wave rectifier 5, an inverter 6, a discharge lamp 7, an output transformer 8, switching transistors 9a and 9b, and a high-frequency Chiyoke coil 10, resonance capacitor 11,
The bias resistors 12a and 12b are similar to those shown in FIG. In this invention, a preheating control circuit 17 and a preheating circuit 25 are newly added.

That is, the preheating control circuit 17 is the trigger circuit 1
8, 20, a delay circuit 19 that determines the preheating start phase, a delay circuit 21 that determines the preheating time, and a DC power source 23 obtained by stepping down the voltage of the AC power source 1 or the like.

The trigger circuit 18 is configured as follows. That is, resistors 18a and 18c are connected in series between the positive and negative output terminals of the full-wave rectifier 5, and the connection point between the resistors 18a and 18c is connected to the base of the transistor 18f via the resistor 18b. It is connected. The emitter of the transistor 18f is connected to the negative pole of the DC power supply 23, and the collector is connected to the positive pole of the DC power supply 23 via the resistor 18d, and is also connected to the input terminal of the delay circuit 19 via the capacitor 18e. . This input terminal is connected to the negative electrode of the DC power supply 23 via a resistor 18g.

Power terminals of this delay circuit 19 are connected to the positive and negative electrodes of a DC power source 23, respectively. The output terminal of the delay circuit 19 is connected to the resistor 20a of the trigger circuit 20.
It is connected to the base of transistor 20d via.

The emitter of this trigger circuit 20 is the DC power supply 23
The collector is connected to the positive electrode of the DC power supply 23 via a resistor 20b, and is also connected to the input end of the delay circuit 21 via a capacitor 20c. The input end of this delay circuit 21 is grounded via a resistor 20f. The trigger circuit 20 is thus configured.

A power terminal of the delay circuit 21 is connected to a positive electrode and a negative electrode of a DC power source 23. The output terminal of this delay circuit 21 is connected through a resistor 22 to the base of a transistor 28 in a preheating circuit 24. The two delay circuits 19 and 21 are each composed of a monostable multivibrator or the like.

Also, the transistor 28 in the preheating circuit 24
The collector of the transistor 28 is connected to the positive terminal of the DC power supply 23, and the emitter of the transistor 28 is connected to the input terminal of the oscillation circuit 27. The output terminal of the oscillation circuit 27 is connected to the base of the transistor 26. The transistor 28 controls the operation of the oscillation circuit 27 and drives the transistor 26. Furthermore, the transistor 26 drives a preheating transformer.

The emitter of the transistor 26 is connected to the negative electrode of the DC power supply 23, and the collector is connected to the positive output end of the full-wave rectifier 5 via the primary winding 25c of the preheating transformer 25. This preheating transformer 25
has two filament windings 25f _{1 and} 25f ₂ , which are connected to preheating electrodes 7f ₁ and 7f ₂ of the discharge lamp 7 _, respectively.

Next, the operation of the discharge lamp lighting device of the present invention configured as described above will be explained. AC power supply 1
When the bidirectional thyristor 3 is turned on, the conduction start phase of the bidirectional thyristor 3 is controlled by the signal from the control device 4, and the bidirectional thyristor 3 has a full-wave rectified voltage (Fig. 4a) due to the total conduction angle of the bidirectional thyristor 3. For example, when the phase is set to θ ₂ as shown in FIG. 4b, DC power is supplied to the inverter 6 via the full-wave rectifier 5 for a period of T ₃ as shown in the input voltage of the inverter 6 in FIG. 4b. be done.

During this period _T3 , base current is supplied to the bases of the switching transistors 9a and 9b of the inverter 6 from the bias resistors 12a and 12b, and self-oscillation occurs as is well known due to the action of the base feedback winding 8b. A high frequency voltage is generated in each winding of the output transformer 8 to light the discharge lamp 7.

In addition, the degree of dimming is achieved by changing the conduction start phase θ ₂ by the dimmer 2 and changing the period T ₃ during which the discharge lamp 7 is lit by applying DC voltage to the inverter 6. It is something.

On the other hand, in the preheating control circuit 17, the AC power supply 1 etc. is stepped down and rectified to provide a DC power supply 23 and an inverter 6.
When an input voltage of is applied, the trigger circuit 18 generates a trigger signal at a phase of θ ₀ when the AC power supply 1 becomes OV, as shown in FIG. 4d.

This trigger signal is applied to the delay circuit 19, the delay circuit 19 operates, and the delay time T ₄ shown in FIG. 4d is reached.
After a period of time has elapsed, an output is generated at a phase of θ ₃ and the output becomes “L”. This output is further transmitted to the trigger circuit 20
The trigger circuit 20 generates a trigger signal with a phase of θ ₃ and applies it to the delay circuit 21 .

When a trigger signal is applied to the delay circuit 21 at a phase of θ ₃ , the output becomes “H” and a predetermined delay time is reached.
After _T5 has elapsed, the output becomes "L" at a phase of _θ4 .
That is, the output of the delay circuit 21 becomes "H" for a period _T5 from the phase θ ₃ to the phase θ ₄ as shown in FIG. 4d.

During the period when the output of the delay circuit 21 is "H", the transistor 28 of the preheating circuit 24 is conductive, the DC power supply 23 is applied to the oscillation circuit 27 through the transistor 28, the oscillation circuit 24 starts oscillating, and the switching operation of the transistor 26 is performed. By the action of the preheating transformer 25, a preheating voltage is generated in the filament windings 25f ₁ and 25f ₂ to preheat the preheating electrodes 7f ₁ and 7f ₂ .

When the output of the delay circuit 21 becomes "L" at a phase of θ ₄ , the transistor 28 is cut off and the oscillation circuit 27 stops oscillating. That is, as shown in FIG. 4c, the discharge current of the discharge lamp 7 flows for a period of T ₃ while the DC power is applied to the inverter 6, and the discharge current of T ₃ flows for preheating of the preheating electrodes 7f ₁ and 7f ₂ . As shown in FIGS. 4d and 4e, the period _T5 is from the phase θ ₃ to the phase θ ₄ .

By performing sufficient preheating during this period _T5 , the time during which no discharge current is flowing is short, so there is almost no drop in the temperature of the preheating electrodes 7f ₁ and 7f ₂ .
The preheating electrode 7f ₁ when the discharge current starts flowing again,
The temperature of 7f ₂ can be kept sufficiently high, and the discharge lamp 7 can be prevented from continuing to discharge during the period when DC power is not supplied from the dimmer 2 to the inverter 6, so that smooth dimming can be performed. It is something.

In addition, since the phase of preheating the preheating electrodes 7f ₁ and 7f ₂ is constant regardless of the degree of dimming, the preheating electrode 7
Since the preheating voltages of f ₁ and 7f ₂ can be kept constant, the life of the discharge lamp 7 can be made equal to that of the conventional device.

FIG. 5 is a circuit diagram showing the configuration of another embodiment of the invention. 5 is the same as the embodiment shown in FIG. 4 except that an output circuit 29 is connected to the preheating control circuit 17 in place of the trigger circuit 20 and delay circuit 21 of the embodiment shown in FIG.

This output circuit 29 mainly includes a transistor 29c. That is, the output of the delay circuit 29 is connected to the base of a transistor 29c via a resistor 29a. The emitter of transistor 29c is connected to the negative electrode of DC power supply 23. The collector of this transistor 29c is connected to the positive electrode of the DC power supply 23 via a resistor 29b, and is also connected to the base of a transistor 28 of the preheating circuit 24 via a resistor 22. Other parts are the same as in FIG. 3.

In the embodiment of FIG. 5 constructed as described above, the output becomes "L" at a phase of θ 6 after the delay time T ₄ of the delay circuit 19 has elapsed, as shown in FIG. ₆ c. This output is output to the output circuit 2 as shown in Figure 6b.
9, the output of the output circuit 29 becomes "H", the transistor 28 becomes conductive, and the preheating circuit 24 operates to preheat the preheating electrodes 7f ₁ and 7f ₂ .

Thereafter, the preheating operation continues until the phase θ ₀ when the AC power supply 1 becomes approximately OV. That is, the preheating electrode 7
Preheating of f ₁ and 7f ₂ is performed using discharge lamp 7 as shown in Figure 6a.
As shown in FIG. 6c, there is a period during which the discharge current flows from the phase θ ₆ until the AC power source 1 becomes approximately OV.

In this way, since the preheating period is set to the latter half of the phase of the output of the dimmer 2, the dimming range is widened, and the time from the end of the preheating period until the discharge current starts flowing again is shortened, and the preheating electrode 7f ₁ ,7f ₂
The decrease in temperature can be further suppressed.

In the above embodiments, the inverter 6 is a push-pull type transistor inverter equipped with a high-frequency choke coil 10, but it goes without saying that other inverters can also be used.

Also, the DC power from the dimmer 2 is transmitted to the inverter 6.
The preheating _control circuit ₁ is shown in FIGS.
7. Although the preheating circuit 24 is shown, the present invention is not limited to the above embodiments as long as it is a means that can achieve this purpose.

In each of the above embodiments, the case where the number of discharge lamps 7 is one is described, but the invention is not limited to this.
Two or more lights may be turned on.

Furthermore, in each of the above embodiments, one inverter corresponds to one dimmer, but it is possible to connect multiple inverters or multiple inverters and a full-wave rectifier to one dimmer or full-wave rectifier. Good too.

As described above, according to the discharge lamp lighting device of the present invention, DC power is applied from the dimmer to the inverter, and the preheating electrode of the discharge lamp is heated during a part of the period when the discharge lamp is lit. Since preheating is used, the preheating electrode can be sufficiently preheated, and the discharge of the discharge lamp can be interrupted during periods when DC power is not supplied to the inverter, resulting in smooth dimming. be.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of a conventional discharge lamp lighting device, and FIGS. 2a to 2d are waveform diagrams of various parts for explaining the operation of the discharge lamp lighting device of FIG.
FIG. 3 is a circuit diagram of an embodiment of the discharge lamp lighting device of the present invention, FIGS. 4a to 4e are waveform diagrams for explaining the operation of the discharge lamp lighting device of FIG. 3, and FIG.
The figure is a circuit diagram of another embodiment of the discharge lamp lighting device of the present invention, and FIGS. 6a to 6c are waveform diagrams for explaining the operation of the discharge lamp lighting device of FIG. DESCRIPTION OF SYMBOLS 1...AC power supply, 2...Dimmer, 5...Full wave rectifier, 6...Inverter, 7...Discharge lamp, _{7f1,7f2 ...}
Preheating electrode, 8... Output transformer, 9a, 9b... Switching transistor, 17... Preheating control circuit, 1
8, 20...Trigger circuit, 18f, 20d, 26,
28...Transistor, 19,21...Delay circuit, 2
5... Preheating transformer, 27... Oscillation circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. An inverter that receives as input a pulsating DC voltage obtained by full-wave rectification of the voltage of an AC power supply, a discharge lamp having a preheating electrode that is lit by the output AC voltage of the inverter, and the AC power supply. and a dimmer that is interposed between the inverter and performs phase control to dim the discharge lamp, a preheating circuit that preheats a preheating electrode of the discharge lamp, and a dimmer that supplies power to the inverter via the dimmer. A discharge lamp lighting device comprising: a preheating control circuit configured to operate the preheating circuit for a predetermined period within a period in which the voltage is applied to preheat the preheating electrode. 2. The preheating control circuit includes a first trigger circuit that generates a trigger signal at a phase when the AC power supply becomes OV;
The claimed invention comprises a delay circuit that is triggered by the output of the first trigger circuit and outputs the output after a predetermined time delay, and an output circuit that inverts the output of the delay circuit and drives the preheating circuit. The discharge lamp lighting device according to scope 1. 3. The preheating control circuit includes a first trigger circuit that generates a trigger signal at a phase when the AC power supply becomes OV;
The first trigger circuit is triggered by the output of this first trigger circuit.
a first delay circuit that delays the output by a predetermined time;
a second trigger circuit that is triggered by the output of the first delay circuit; and a second trigger circuit that is triggered by the output of the second trigger circuit, delays by a second predetermined time, outputs the signal, and drives the preheating circuit for a predetermined time. 2. The discharge lamp lighting device according to claim 1, comprising: 2 delay circuits. 4. The preheating circuit includes a first transistor driven by the output of the preheating control circuit, an oscillation circuit that performs an oscillation operation when the first transistor is turned on, and a second transistor that is turned on by the output of the oscillation circuit. The discharge lamp lighting device according to claim 1, further comprising a preheating transformer that applies a voltage to the preheating electrode when the second transistor is turned on.