JPH0154838B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is applicable to
This invention relates to a discharge lamp lighting device that can always sufficiently preheat the filament of a discharge lamp.

FIG. 1 shows a conventional discharge lamp lighting device, in which a discharge lamp ballast 3 is connected to a commercial power source 1 via a discharge lamp dimmer 2, and the output of the discharge lamp ballast 3 is The discharge lamp 4 is turned on. 5 is a filament preheating transformer, the primary winding of which is connected to the output side of the discharge lamp dimmer 2. By the way, in such a device, when starting the discharge lamp 4, if the dimming level of the discharge lamp dimmer device 2 is set low, the effective input voltage applied to the filament preheating transformer 5 will also be low, and the discharge lamp will start. 4 had the disadvantage that the preheating current was insufficient. If the preheating current of the discharge lamp 4 becomes insufficient in this way, the amount of thermionic emission from the filament 6 will be insufficient, and a cold cathode discharge will actually occur, which will significantly deteriorate the filament 6 and cause the discharge lamp to deteriorate. The disadvantage was that the lifespan of 4 was shortened. Of course, if the primary winding of the filament preheating transformer 5 is directly connected to the commercial power supply 1, the preheating current will always be constant. The disadvantage was that it required a common three wires to connect between the lines, which required a lot of work for the wiring work. Conventionally, as shown in FIG. 2, the bidirectional thyristor 8c is turned on for a certain period of time after energization by the action of the delay timer 7, and the filament 6 of the discharge lamp 4 is preheated to increase the thermionic emission effect. A discharge lamp lighting device has been proposed in which a lighting voltage is applied to the discharge lamp 4 with the bidirectional thyristor 8c in a non-conducting state, but even in such a device, the dimming level of the discharge lamp dimmer 2 is When the temperature is low, the filament 6 of the discharge lamp 4 is not sufficiently preheated, and startup due to cold cathode discharge may occur, resulting in a disadvantage that the life of the discharge lamp 4 is shortened.

The present invention has been made in order to eliminate such drawbacks of the conventional example, and it is possible to always sufficiently preheat the filament regardless of the dimming level of the discharge lamp dimming device, and the filament can be preheated sufficiently. Provided is a discharge lamp lighting device that prevents the discharge lamp from turning off due to insufficient preheating or forced starting due to cold cathode discharge, reduces stress on the discharge lamp, and extends the life of the discharge lamp. The purpose is to

The configuration of the present invention will be explained below with reference to illustrated embodiments. As shown in FIGS. 3 to 7, a commercial power source 1
In a discharge lamp lighting device, a discharge lamp ballast 3 is connected to a discharge lamp dimmer 2 via a discharge lamp dimmer 2, and a discharge lamp 4 is lit by the output of the discharge lamp ballast 3. A delay timer 7 whose delay time becomes longer as the effective output voltage decreases is provided, and a switching element 8 is provided which prevents the lighting voltage from being applied to both ends of the discharge lamp 4 during the delay operation of the delay timer 7. During the delay operation, a filament preheating means 5a is provided for supplying a preheating current proportional to the effective output voltage of the discharge lamp dimmer 2 to the filament 6 of the discharge lamp 4. Third
In the embodiment shown in FIG. 4 and FIG. 4, the discharge lamp dimmer 2 is most commonly constructed using a phase control type dimmer using a bidirectional thyristor such as a triac. It is also possible to use an amplitude control dimming device that controls the amplitude itself of the traffic power supply voltage. The delay timer 7 is connected to the output side of the discharge lamp dimmer 2, and is configured such that its delay time becomes longer as the effective output voltage of the discharge lamp dimmer 2 becomes smaller.
FIGS. 5 and 6 show an example of the delay timer 7, which is used as the delay timer 7 in the embodiments shown in FIGS. 3 and 4, respectively.
First, to explain the operation of the delay timer 7 shown in FIG. It is full-wave rectified by and stored in the smoothing capacitor _C0 . The terminal voltage V _c0 of this capacitor C ₀ increases according to the effective output voltage of the discharge lamp dimmer 2, and therefore the output voltage of the time constant circuit 11 consisting of the resistor R ₁ and the capacitor C ₁ , In other words, the rate of increase in the terminal voltage V _c1 of capacitor C _{1 is}
It changes depending on the magnitude of the terminal voltage V _c0 . The graph shown in Figure 7 shows how the terminal voltage V _c1 of capacitor C ₁ changes, and as shown in the figure, when the terminal voltage V _c0 of capacitor C ₀ is large, the rate of increase in terminal voltage V _c1 is However, when the terminal voltage V _c0 of the capacitor C ₀ is small, the rate of increase becomes low. The terminal voltage V _c1 of such capacitor C ₁ is PUT1
The voltage is applied to the anode terminal of 2, and this PUT
A constant reference voltage V ₀ determined by a Zener diode ZD is applied to the gate terminal of No. 12. Therefore, the PUT 12 becomes conductive when the terminal voltage V _c1 of the capacitor C ₁ exceeds the reference voltage V ₀ , and thereafter remains in the conductive state. The timing at which the PUT 12 becomes conductive changes depending on the terminal voltage V _c0 of the capacitor C ₀ , that is, the effective output voltage of the discharge lamp dimmer 2, and as shown in FIG. When the power switch 13 of the discharge lamp lighting device is turned on, the PUT 12 becomes conductive relatively early at time t ₁ when the effective output voltage of the discharge lamp dimmer 2 is large, but when the effective output voltage is small, the PUT 12 becomes conductive. At time _t2 , the PUT 12 becomes conductive with a slight delay. In the delay timer 7 shown in FIG. 5, the output of PUT12 is connected to the transistor inverter 1
4 and is applied to the gate input of the bidirectional thyristor 8a as shown in FIG. When preheating of the discharge lamp 6 is performed and the PUT 12 becomes conductive, the thyristor 8a becomes non-conductive, and a lighting voltage is applied to both ends of the discharge lamp 4. The preheating time of the filament 6 is configured to become longer as the effective output voltage of the discharge lamp dimmer 2 becomes lower, so that the filament 6 of the discharge lamp 4 is It will always be sufficiently preheated. On the other hand, the delay timer 7 shown in FIG. 6 is used in the embodiment shown in FIG. The lighting voltage is applied to the In this embodiment, the filament preheating current of the discharge lamp 4 is always supplied to the filament 6 via the filament preheating transformer 5, so that the preheating current continues to flow even after the discharge lamp 4 is lit. It's summery. In any of the above embodiments, the discharge lamp ballast 3 may be a normal iron core type ballast using an inductance, or a semiconductor type ballast using an inverter or the like.

The discharge lamp lighting device shown in FIG. 8 preheats the filament 6 by keeping the preheating current of the filament 6 constant regardless of the effective output voltage of the discharge lamp dimmer 2 using a thyristor phase control method. It is designed to be able to carry out the following to a sufficient extent. Figure 9 shows its operating waveform diagram, and Figure a
indicates the conduction phase angle θ ₁ when the dimming level by the discharge lamp dimmer 2 reaches the lower limit of dimming, and the conduction phase angle θ ₁ is smaller than the state shown in FIG. It's something that never happens. Figure b shows the conduction phase angle θ ₂ of the thyristor 16 in the filament preheating circuit 15, and this conduction phase angle θ ₂ is always set to be smaller than the conduction phase angle θ ₁ . Therefore, the output voltage of this thyristor 16 is always constant regardless of the effective output voltage of the discharge lamp dimmer 2. 5 is thyristor 16
This is a filament preheating transformer for boosting the output voltage of the device to an appropriate voltage value. In the device shown in FIG. 8, only a phase control system using a thyristor can be used as the discharge lamp dimmer 2, but in the discharge lamp dimmer of the present invention shown in FIGS. 3 to 7, the above-mentioned In addition to the phase control method, an amplitude control method can also be used.

The present invention is constructed as described above, and includes a discharge lamp lighting system in which a discharge lamp ballast is connected to a commercial power source via a discharge lamp dimmer, and the discharge lamp is lit by the output of the discharge lamp ballast. In the device, a switching element is provided with a delay timer whose delay time becomes longer as the effective output voltage of the discharge lamp dimmer decreases, and which prevents a lighting voltage from being applied to both ends of the discharge lamp during the delay operation of the delay timer. and a filament preheating means for supplying a preheating current proportional to the effective output voltage of the discharge lamp dimmer to the filament of the discharge lamp at least during the delay operation. Even if you start the discharge lamp from a low output level,
When the filament preheating current is low, the preheating time becomes longer, so the filament is always sufficiently preheated regardless of the dimming level, so thermionic emission from the filament is always active. Therefore, there is no possibility of lighting failure or starting due to cold cathode discharge, and the stress applied to the discharge lamp can be reduced and the life of the discharge lamp can be extended.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional example, FIG. 2 is a block diagram of another conventional example, FIG. 3 is a block diagram of an embodiment of the present invention, and FIG. 4 is a block diagram of another embodiment of the same. Fig. 5 is a circuit diagram of the delay timer used in the embodiment of Fig. 3, Fig. 6 is a circuit diagram of the delay timer used in the embodiment of Fig. 4, Fig. 7 is an explanatory diagram of the operation of the delay timer, and Fig. 8 9 is a block diagram of another discharge lamp lighting device, and FIGS. 9a and 9b are operation explanatory diagrams of the same. 1 is a commercial power supply, 2 is a discharge lamp dimmer, 3 is a discharge lamp ballast, 4 is a discharge lamp, 5 is a filament preheating transformer, and 7 is a delay timer.

Claims (1)

[Scope of Claims] 1. A discharge lamp lighting device in which a discharge lamp ballast is connected to a commercial power source via a discharge lamp dimmer, and the discharge lamp is lit by the output of the discharge lamp ballast. A delay timer whose delay time becomes longer as the effective output voltage of the dimmer decreases is provided, and a switching element is provided to prevent the lighting voltage from being applied to both ends of the discharge lamp during the delay operation of the delay timer. A discharge lamp lighting device comprising: a filament preheating means for supplying a preheating current proportional to an effective output voltage of the discharge lamp dimmer to the filament of the discharge lamp during the delay operation. 2. One ends of the first and second filaments provided at both ends of the discharge lamp are connected to a discharge lamp ballast, and the other ends are connected to each other via a bidirectional thyristor,
During the delay operation of the delay timer, the bidirectional thyristor is turned on to preheat both filaments, and after the delay operation, the bidirectional thyristor is turned off and a lighting voltage is applied to both ends of the discharge lamp. Claim 1 characterized in that
Discharge lamp lighting device as described in . 3. A bidirectional switching element is interposed between the discharge lamp ballast and the discharge lamp, and the output of the delay timer is bidirectionally switched so that the bidirectional switching element becomes conductive after the delay timer operates. 2. The discharge lamp lighting device according to claim 1, wherein the voltage is applied to a gate input of an element.