JPH0221594A - High voltage pulse generator for electric discharge lamp - Google Patents

Abstract

PURPOSE:To obtain a voltage sufficiently capable of lighting even if an electric discharge lamp is still hot and reduce heating by using a coil for ballast to superpose a high voltage obtainable with charge and discharge of a capacitor on that ballast coil. CONSTITUTION:When power is turned on, a capacitor C1 is rapidly charged by DC power E and a signal is given to the gate of a transistor Q1 from a pulse synchronous circuit 10 after a time of t1 (after charging time of the capacitor C1 elapses). The transistor Q1 is on by this gate signal and a charge of the capacitor C1 is discharged through a coil 7, a resistor R1 and the transistor Q1 for generating a high voltage. Then, the capacitor C1 is charged and discharged by the switching control of this pulse synchronous circuit 10 so that a high voltage is superposed on the ballast coil 6. This makes it possible to surely light up an electric discharge lamp 4 even when it is hot immediately after its lights-out, and also to reduce heating because the coil 6 is used for ballast.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-voltage pulse generator for a discharge lamp that boosts an alternating current voltage output from an inverter and supplies it to a discharge lamp.

[Conventional technology]

As a device for lighting a discharge lamp using an inverter,
For example, there is one shown in FIG.

In the figure, 1 is a power supply unit that obtains a stable DC voltage from an AC or DC power supply, and 2 is a DC' output from the power supply unit l.
3 is a step-up transformer that boosts the AC voltage and supplies it to the discharge lamp 4; 5 is the secondary side of the step-up transformer 3 and the discharge lamp; This is a ballast resistor interposed between 4 and 4.

In the device configured as described above, the DC voltage output from the power supply unit 1 is converted into an AC voltage by the inverter 2, and this AC voltage is stepped up by the step-up transformer 3 and supplied to the discharge lamp 4. At this time, the inverter 2 generates a voltage with a frequency of kl□ to several tens of kHz□, and this AC vL voltage is increased by the step-up transformer 3 to a voltage of about 400v to 1000v.

The discharge lamp 4 is then turned on by this high AC voltage.

(3 problems to be solved by the invention) However, when a discharge lamp is turned on, the temperature of the lamp (tube) rises, so when turning off the discharge lamp and then turning it on again, a lighting voltage of several kV to several mokv is supplied. Although it is necessary, L
Conventional high-voltage generators such as the one described above have the problem that they can only generate a voltage of about 1000V as mentioned above, so the jet cannot be lit until the discharge lamp has cooled down. Furthermore, when the circuit shown in FIG. 3 is used to generate a high voltage of several kilovolts, there is a problem in that the loss in the ballast resistor is large and heat is generated.

This invention was made with attention to these problems, and allows the discharge lamp to be lit reliably even when it is hot.
The present invention also provides a high-voltage pulse generator for a discharge lamp that generates less heat.

(Means for Solving the Problems) A high-voltage pulse generator for a discharge lamp according to the present invention includes a ballast coil interposed between the secondary side of a step-up transformer and a discharge lamp, and a ballast coil connected to the ballast coil. A high voltage generation coil with a small number of turns is connected, a capacitor is connected to one end of this high voltage generation coil, and a switching element for charging and discharging the capacitor is connected to the other end, and this switching element is connected to the cycle of the step-up transformer. A pulse synchronous circuit is provided to perform switching control in accordance with the ballast coil, and the switching control of this pulse synchronous circuit charges and discharges the capacitor to superimpose a high voltage on the ballast coil.

Further, in the high-voltage pulse generator for a discharge lamp of the present invention, a control coil capable of controlling the current flow is provided in an insulated state in the ballast transformer around which the ballast coil is wound, and the current flowing through the control coil is controlled to increase the inductance. It is made to be variable.

[Effect]

In the high-pressure pulse generator for discharge lamps of this invention, a coil is used for the ballast, and the high voltage obtained by charging and discharging the capacitor is superimposed on this ballast coil, so even if the temperature of the discharge lamp is high, it is sufficient. It is possible to obtain a voltage that allows lighting, and also to reduce heat generation.

Further, by controlling the current flowing through the control coil, the inductance of the ballast coil can be varied, and a ballast suitable for the discharge lamp can be made.

(Embodiment) FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention.
The same reference numerals as in FIG. 3 indicate the same components. In the figure, 1 is a power supply unit that outputs a stable DC voltage, 2 is an inverter that converts the DC voltage into AC voltage, 3 is a step-up transformer that boosts the AC voltage output from the inverter 2, and 4 is a load. A discharge lamp, 6 a ballast coil interposed between the secondary side of the step-up transformer 3 and the discharge lamp 4;
is a high voltage generation coil connected to the ballast coil 6,
The number of turns N of this high voltage generation coil 7 is the ballast coil 6
The number of turns is less than N2 (Nl <N2) and is 6
Reference numeral 8 denotes a control coil (number of turns N3) that is provided insulated from the ballast coil 6 and is capable of controlling current, and constitutes a ballast transformer 9 together with the ballast coil 6 and the high voltage generating coil 7.

C1 is a capacitor connected to one end of the high voltage generating coil 7, and a DC type #E is connected in parallel with this capacitor. Ql is a transistor connected to the other end of the high voltage generating coil 7 via a current limiting resistor R1, and is provided as a switching element for charging and discharging the capacitor C1. ZNR is a surge absorber provided to protect the transistor Q, 10 is a pulse synchronous circuit that controls the switching of the transistor Q1 in accordance with the cycle of the step-up transformer 3, D, to D4 are diodes, Q2 is a transistor, R2 and R3 are It is resistance.

Next, the operation will be explained using the waveform diagram shown in FIG.

FIG. 2 shows the applied voltage when the discharge lamp 4 starts lighting and the gate voltage of the transistor Q1 at that time.

Similar to the device shown in Fig. 3, a voltage obtained by boosting the output AC voltage of the inverter 2 to several hundred volts by the step-up transformer 5 is applied to the discharge lamp 4, but at the start of lighting, high voltage is superimposed as shown in Fig. 2. This voltage is applied to the discharge lamp 4. That is, when the power is turned on, the capacitor C1 is rapidly charged by the DC power supply E, and after t+ [sec] time (after the charging time of the capacitor C2 has elapsed), the pulse synchronization circuit 10 is charged at the timing shown in FIG. A signal is applied to the gate of transistor Q. This data No. 818 turns on the transistor Q, and the charge in the capacitor C1 is discharged through the high voltage generating coil 7, the resistor R1, and the transistor Q1. Then, the capacitor C1 is charged and discharged by the switching control of the pulse synchronization circuit 10,
High voltage is superimposed on the ballast coil 6.

At this time, the voltage V1 generated in the high voltage generating Coria is expressed as follows. In addition, the voltage V2 generated in the ballast coil 6 is as follows, and by substituting equation (A) into equation (B), it is possible to generate a high voltage pulse of several kV to several + kV, and this high voltage pulse boosts the voltage. It is superimposed on the voltage Va from the transformer 5 and applied to the discharge lamp 4. For this reason, the discharge lamp 4
The light can be turned on reliably even when it is hot right after the light has been turned off.
Furthermore, since the coil 6 is used as the ballast, heat generation can be reduced.

Then, when the discharge lamp 4 is turned on by the high-voltage pulse, the pulse synchronization circuit 10 detects that current has flowed through the discharge lamp 4, and stops the gate signal to the transistor Q1. As a result, the generation of the high voltage pulse is stopped and the applied voltage returns to the voltage applied during normal lighting.

Here, in order to generate a high voltage pulse, the turns ratio and the transistor Q2 are turned off, and both ends of the IIJ control coil 8 are shorted. As a result, the inductance 2 of the high-voltage generating coil 7 and the ballast coil 6 of the transformer 9 becomes smaller, current flows more easily, and circuit loss decreases.

At this time, by controlling the current flowing through the control coil 8, the inductances L, L2 of the high voltage generating coil 7 and the ballast coil 6 can be varied, and the discharge lamp 4
It is possible to use a ballast suitable for

In the above embodiment, it is necessary to wind the ballast coil 7 with the high voltage generating coil 7, but this increases the inductance L2 of the ballast coil 6. This inductance L2
If the output frequency of the inverter 2 is f[11,], then L2=2πfL, and if this is too large, it becomes difficult for the current to flow. Therefore, in this embodiment, the control coil 8
is provided in the ballast transformer 9, and the pulse synchronization circuit 10 can detect the flow of current into the discharge lamp 4 and generate the necessary high-voltage pulse arbitrarily, but it is possible to reduce the charging time of the capacitor C1. By doing so, the discharge lamp 4 can be turned on instantly.

(Effects of the Invention) As described above, according to the present invention, a coil is used for the ballast, and the high voltage obtained by charging and discharging the capacitor is superimposed on the ballast coil, so that the temperature of the discharge lamp decreases immediately after the lamp is turned off. This has the effect that a sufficient voltage for lighting can be obtained even when it is hot, the discharge lamp can be lit reliably, and heat generation can be reduced.

In addition, by controlling the current flowing through the control coil, the inductance of the ballast coil can be varied, resulting in the effect that the ballast can be made suitable for the discharge lamp.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a waveform diagram showing the operation of the circuit shown in FIG. 1, and FIG. 3 is a block diagram showing a conventional device. 1--------Power supply section 2-----Inverter 3 ・-----Step-up transformer 4----Discharge lamp 6--Ballast coil 7--High voltage generation coil 8 -------Control coil 9...Ballast transformer...Capacitor...Transistor (switching element)

Claims (2)

[Claims] (1) In a high-voltage pulse generator that boosts the AC voltage output from an inverter using a step-up transformer and supplies it to a discharge lamp, a ballast coil is interposed between the secondary side of the step-up transformer and the discharge lamp, and A high voltage generation coil with a smaller number of turns than the ballast coil is connected to this ballast coil, a capacitor is connected to one end of this high voltage generation coil, and a switching element for charging and discharging the capacitor is connected to the other end. A pulse synchronous circuit is provided for controlling switching of a switching element in accordance with the cycle of the step-up transformer, and the switching control of the pulse synchronous circuit charges and discharges the capacitor, thereby superimposing high voltage on the ballast coil. High-pressure pulse generator for discharge lamps. (2) a ballast transformer around which the ballast coil is wound is provided with an insulated control coil capable of controlling the current;
2. The high-pressure pulse generator for a discharge lamp according to claim 1, wherein the inductance is varied by controlling the current flowing through the control coil.