JPS60208094A - Device for firing discharge lamp - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Technical field of invention The present invention relates to a discharge lamp lighting device.

Technical Background of the Invention and Problems Therein Generally, in an apparatus for lighting a discharge lamp using an inverter transformer, it is desirable to sufficiently preheat the filament 1 and warm start it.

Figure 1 shows an example of a conventional AC power supply l.

Inverter transformer 2, inverter transformer 3 and discharge lamp 4
In the lamp circuit, a switch element 5 is connected between the filaments 4a and 4b of the discharge lamp 1, and the switch element 5 is turned on by a timer circuit 6 for a certain period of time after the power is turned on.
This preheats the filament. However, when the secondary circuit is opened and closed by the switch element 5 in this manner, a high voltage withstand element is required as the switch element, resulting in high cost and large drive power.

This is because hllE of the transistor becomes smaller. Furthermore, in this method, the preheating current is small and preheating takes time. In this regard, in order to increase the preheating current, a method has been considered in which a differential winding is provided on the secondary side of the inverter transformer and a switch element is used to short-circuit at startup, but this switch element also has a high withstand voltage of 600 to 800 ■ class Q. This requires an element.

On the other hand, there is also a rapid method as shown in FIG.

In this method, the output voltage on the secondary side is lowered by lowering the input voltage of the inverter circuit or changing the oscillation mode to cause a warm star. However, as the secondary voltage decreases, the filament voltage also decreases, making it impossible to preheat the filament sufficiently in a short time.

In order to warm start the ν1 station, it is necessary to preheat the filament by lowering the secondary voltage of the inverter transformer without lowering the filament voltage.

In addition, in a discharge lamp lighting device, there are cases where it is desired to turn off dimmed lighting, but this is achieved by disabling the inverter circuit.

Safety measures against lamp load abnormalities are also necessary, and this safety circuit also makes the inverter circuit a one-of-a-kind product. Therefore, the number of switching elements increases due to these effects.

Purpose of the Invention The present invention has been made in view of the above points, and it is easy to control the secondary voltage so as to contribute to warm start, and also contributes as a safety circuit in the case of dimming lighting and lamp load abnormality. An object of the present invention is to obtain a discharge lamp lighting device equipped with an inverter transformer.

Summary of the Invention The present invention includes an inverter transformer wound with a control winding that forms a local magnetic saturation area by applying a DC voltage or a pulse voltage to a part of the secondary core. When the control winding is energized, its local magnetic saturation portion weakens the coupling between the secondary core and the secondary voltage becomes low. The device is configured so that a warm star can be activated by passing a preheating current, and the dimming lighting and safety functions can also be handled by such a drop in secondary voltage.

Embodiment of the Invention An embodiment of the present invention will be explained with reference to FIGS. 3 to 5. First, the structure of the inverter transformer 10 is shown in the third figure. This is based on a leakage transformer with an iron core structure in which the secondary E-type core 11 and the secondary E-type core 12 are opposed to each other with a gap (space 'J') 1 :() between them. Control cores 14a and L4b, which are divided into two parts, are attached to the tip of the central leg 12c of the secondary E-shaped core 12.The central leg lie of the secondary E-shaped core 11 is connected to the primary winding Nl. , a bias winding Nu is wound around, and a secondary winding RIANz is wound around the central leg 12c of the secondary E-shaped core 12. Also, control windings Ncd, Ncb is wound.

Here, the winding wires Nca and Ncb are connected in series as shown in FIG. 4, with terminals T a and T at both ends.
By applying a DC voltage or a pulse voltage between the control cores 14a and 14b, magnetic flux of opposite polarity is applied to the control cores 14a and 14b as indicated by arrows, thereby forming a local magnetic saturation section 15. .

Therefore, by applying a DC voltage or a pulse voltage to the control windings N ca and N eb , the central leg 1 of the secondary E-shaped core 12
By magnetically saturating the tip of 2c and forming a local magnetic saturation part 15, the magnetic resistance of this part becomes similar to that of the near gap, and the coupling between - and secondary is weakened, so that the secondary winding N ) is caused by a decrease in the secondary voltage generated.

Therefore, FIG. 5 shows such an inverter transformer 10.
This figure shows a discharge lamp lighting device using a discharge lamp. First, the negative winding N1 is connected to an AC power source 17 via an inverter circuit 16. Further, both ends of the secondary winding N2 are connected to filaments 18a and 18b of the discharge lamp 18. A preheating transformer 19 is provided for the discharge lamp 18. . This preheating transformer 19 has a secondary side preheating winding N+.
a, Np and b are connected to the filaments 1ga and 18b, and the negative winding Ndo 1 is connected to the bias winding Nu via a switch element controlled by a timer circuit 20, such as a bidirectional thyristor 21. . On the other hand, the above-
For the next side control windings Nca and Neb, terminals Ta and Tb
A DC bias circuit 22 that applies a DC voltage between them is provided. This negative current bias circuit 22 and the bias winding N11 for the preheating transformer 19 are shared as a power source, and the timer circuit 20 and thyristor 21 are also
illll, this 0. In addition, it is composed of a diode 23 and a capacitor 24.

In such a configuration, when the power switch is turned on, the timer circuit 20 is activated and the thyristor 21 is turned off for a certain period of time.
Do N. As a result, the preheating transformer 19 operates using the bias winding Nu as a power source, and the filaments 18a and 18b
A preheating current flows through the

At this time, the secondary voltage of the secondary winding Nl of the inverter transformer 10 is decreasing. That is, by turning on the thyristor 21 and by turning on the current bias circuit 22, the control winding Nca,
A DC voltage is applied to Ncb, and the local magnetic saturation part 1
5 is formed, and as explained in FIG. 4, the coupling between the two dimensions is weakened.

In this way, the secondary voltage of the inverter transformer 10 does not drop and discharge does not occur, and the filament 18a
, 18b, a sufficient preheating current flows through them without reducing the filament voltage, so that the filament temperature rises in a short time.

Thereafter, when the thyristor 21 is turned off after a certain period of time determined by the timer circuit 20 has passed, the control windings Nea, Nc
The DC bias for b is cut.

As a result, the local magnetic saturation portion 15 is eliminated, and the control cores 14a, 14b act in the same manner as the central leg 12e.
Since the coupling between the secondary windings becomes steady, the secondary voltage generated in the secondary winding N2 also rises and becomes a steady state, and the filament 18a
, 18b, and the discharge lamp 13 is turned on. A warm start is performed in this way, but
At this time.

The preheating transformer 19 also ceases to function, and filament cutting is performed at the same time. In other words, according to this embodiment,
The transistor 21 can perform warm start control and filament power cut control at the same time, and it is possible to simplify and save power without providing a separate filament power cut circuit. Also, the switching elements such as this thyristor 21 should have a withstand voltage of 100V (
There is no need for a high-voltage element, making it inexpensive. Furthermore, since the oscillation mode of the inverter circuit 16 is not changed, no stress is applied to the switching transistor.

By the way, one end of the negative winding Np+ may be directly connected to the bias winding Nu without using the thyristor 21, as shown by the broken line in FIG. 5, so that the filament is constantly preheated. This is effective when lighting the discharge lamp 18 in a controlled manner. That is, since the lamp current decreases when lighting is dimmed, by preheating the filament for 1:30°, the temperature of the socket 1, which affects the lamp life, is compensated for and kept approximately constant. With this valve λ, preheating is always performed even when all lights are on, so using a dimming detection circuit, a timer circuit, a switch element, etc., the filament is preheated only at the start when all lights are on, and when the lights are dimmed, the filament is preheated only at the start. The filament may be preheated at all times.

Further, by using the inverter transformer 10 of the present invention, it is possible to control the lighting without making the inverter circuit 16 inoperable. An example of this application is shown in FIG. Specifically, for the circuit shown in FIG.
A timer circuit 20 and a pulse generator 27 whose duty is adjusted by a variable resistor 26 are connected to the gate of the pulse generator 27 via an OR gate 25.

According to this, for a certain period of time after power is turned on, the timer circuit 20
Under the control of , the thyristor 21 performs the above-mentioned filament preheating operation and soft star 1 operation in ONL (
At this time, even if a pulse signal is output from the pulse generator 27, the OR gate 25 gives priority to the timer output and has no effect.

However, after the timer circuit 20 times up,
Dimming lighting control is performed in accordance with the pulse output from the pulse generator 27. That is, during the pulse output period by the pulse generator 27, the thyristor 21 is turned ON again, and the control winding N
A DC pulse voltage is applied to ea and Net+, forming a local magnetic saturation section 15 and lowering the lamp applied voltage, but during the pulse pause period of the pulse generation 'It i'N 127, the thyristor 21 is set to 01.F. Control winding Nca,・N
The DC bias of cb is cut and the secondary voltage (lamp applied voltage) increases.

Therefore, the duty 84 is adjusted by the 5 variable resistor 26.
By moving the lamp, the tune of the voltage applied to the lamp can be changed, and dimming can be performed. Therefore, inverter times! ii]
This allows dimming and lighting to be performed without disabling G, and a dedicated switch element is not required.

Moreover, when the lamp is turned off, the filament is preheated by the preheating transformer 19, resulting in extremely low power consumption, stabilizing the cathode spot temperature, and achieving good dimming lighting at fT.
You can do it.

Furthermore, by using the inverter transformer lO, a stabilizing circuit can be constructed in the event of lamp load abnormality. That is, although not shown in the drawings, by configuring the control windings Ncd and NCLI to apply a DC voltage when a negative 6:1A lamp is detected, the secondary voltage decreases and the discharge is reduced. This is equivalent to disconnecting the electric light 18 from the secondary winding N2. Therefore, without rendering the inverter circuit 16 inoperable, the lamps are protected, damage to the lamps is prevented, and it is possible to leave the room safely.

FIG. 7 shows a modification example in which different control cores 14a, 1
Without using the central leg 12cf ((rikawa), a hole 28 is formed in a part of the central leg and a control winding Nd, 5Ncb is applied to generate a magnetic flux as shown by the arrow and the local magnetic saturation area is 1
5.

Although E-shaped cores are used on the primary and secondary sides in this embodiment, a combination of U-shaped cores, a combination of vase-shaped cores with silk, etc. can be similarly applied.

Also, in Figures 5 and 6, the diode 223L;
A current limiting impedance such as a resistance, inductance, or capacitance may be connected in series.

Effects of the Invention As described above, the present invention includes an inverter transformer in which a control winding is wound around a part of the central leg of the secondary core to form a local magnetic saturation area by applying a DC voltage or a pulse voltage.・If this control winding is energized for a certain period of time, its local magnetic saturation will weaken the secondary side temperature coupling and lower the secondary voltage, and in this state the filament preheats. By doing this, you can perform a warm start, and in the same way, you can control dimmed lighting and lamp load abnormalities without making the inverter circuit inoperable.
The safety measures '1 can also be taken.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing a conventional example, Fig. 2 is a circuit diagram showing a different conventional example, Fig. 3 is a circuit diagram showing an example of an undiscovered invention, and Fig. 4 is a partially enlarged circuit diagram. 5 is a circuit diagram, FIG. 6 is a circuit diagram showing an applied example, and FIG. 7 is a side view showing a modified example. 11...-Next side E'JJa Koge (-Next side core), 12
・Secondary side E-type core (secondary side core), 13 ・Gap, 15...Local magnetic saturation part, 18...Discharge lamp, N
2... Secondary winding, N ea - N eb... Control winding ratio Applicant Toshiba Electric Materials Corporation, %J Country, 757-Fig.

Claims (1)

[Claims] The discharge lamp lighting device is equipped with an inverter transformer in which the secondary cores are opposed to each other through a gap, and a secondary winding to which the discharge lamp is connected is wound around the secondary core. A discharge lamp lighting device characterized in that a control winding is wound around a part of the secondary core of the inverter transformer to form a local magnetic saturation region by applying a DC voltage or a pulse voltage.