JPH11329781A - Light modulating transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light modulating transformer that can miniaturize a circuit board on which a high-frequency lighting device capable of modulating the light of a high-voltage discharge lamp is mounted and can reduce the mounting work to the circuit board. SOLUTION: This light modulation transformer T4 is provided with a primary coil L11 that is so wound on an iron core having first to fourth iron leg parts 12b, 13b-12e, 13e formed on the four corners of yokes 12a 13a as to straddle the first and second iron leg parts 12b, 12c and is connected to a control power source, and a secondary coil L12 that is so wound as to straddle the second and third iron leg parts 13c, 13d and is connected to a lighting circuit of a discharge lamp 1, and thus, light modulation is performed by the single light modulating transformer by preventing the interlinkage between the magnetic flux ϕ1 generated by the primary coil L11 and the secondary coil L12 and between the magnetic flux ϕ2 generated by the secondary coil L12 and the primary coil L11 and thereby preventing a high voltage from being induced in the primary coil L11 by the secondary coil L12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dimming transformer used for dimming a high-pressure discharge lamp.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a circuit of a high-frequency lighting device capable of dimming a high-pressure discharge lamp such as a hot cathode discharge lamp, a cold cathode discharge lamp, a neon lamp, and a xenon lamp. The discharge lamp 1 is connected to a secondary coil L2 of an oscillating transformer T1 of an inverter 2 for converting into a high frequency and high voltage.

As is well known, the inverter 2 alternately turns on and off the transistors Q1 and Q2 by a voltage generated in the feedback coil L3, and alternately changes the direction of the current flowing through the primary coil L1 of the oscillation transformer T1. Reverse, thereby converting the voltage of the DC power supply 3 to AC,
A high-frequency high voltage is generated in the secondary coil L2. Then, the voltage generated in the secondary coil L2 of the oscillation transformer T1 is applied to the discharge lamp 1, and the discharge lamp 1 is turned on.

In this example, the dimming of the discharge lamp 1 is performed by inserting the transformers T2 and T3 into a lighting circuit composed of the secondary coil L2 of the oscillation transformer T1 and the discharge lamp 1, and the primary coils of the transformers T2 and T3. By supplying current from the control power supply 4 to L6 and L7, the discharge lamp 1 of each transformer T2 and T3
The lamp current is increased by decreasing the inductance of the secondary coils L4 and L5 connected to the primary coil L4.
6, dimming is performed by reducing the current flowing through L7 and increasing the inductance on the secondary side of each of the transformers T2 and T3 to reduce the lamp current.

The reason for using the transformers T2 and T3 and the two transformers is that, for example, if only one of the transformers T2 is used, the secondary coil L4 of the transformer T2 is connected to the high frequency high voltage circuit, so that the primary coil L6 is used. , A high-frequency high voltage is induced. This voltage is supplied to the control power supply 4 or the smoothing capacitor C
2 may be destroyed.

In order to avoid this destruction, two transformers T
2 and T3, the secondary coils L4 and L5 of the transformers T2 and T3 are connected in series and connected to the discharge lamp 1, and the primary coils L6 and L7 of the transformers T2 and T3 are inverted in polarity with respect to each other. By connecting in series and connecting to the control power supply 4, the high frequency high voltage induced in the primary coils L6 and L7 is canceled.

FIG. 4 shows the structure of a transformer section inserted into the lighting circuit. Each of the transformers T2 and T3 is formed by an E-type core 6a and an I-type core 6b.
2. Primary coils L6, L are attached to the center leg of the E-shaped core 6a of T3.
7 and secondary coils L4 and L5 are wound. And
The primary coils L6 and L7 of the transformers T2 and T3 are connected in series with the same polarity, and the secondary coils L4 and L5 are connected in series with inverted polarities.

[0008]

However, in such a configuration using two transformers for dimming the discharge lamp,
The circuit board on which the high-frequency lighting device is mounted needs a space for mounting two transformers. Therefore, a large circuit board is required, so that the circuit board cannot be downsized. is there.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made to reduce the size of a circuit board on which a high-frequency lighting device capable of dimming a high-pressure discharge lamp is mounted and to mount the circuit board on a circuit board. An object of the present invention is to provide a dimming transformer that can reduce labor.

[0010]

According to the present invention, there is provided an iron core having first to fourth iron legs connected to each other by a yoke, and wound around the first and second iron legs, A primary coil connected to a control power supply; and a secondary coil wound over the second and third legs and connected to a discharge lamp, wherein the first and fourth legs are provided. Part and the second
And two closed magnetic paths via the third leg portion are used as the closed magnetic paths for the primary coil, and two closed magnetic paths via the second and first leg portions and the third and fourth leg portions are provided. The closed magnetic path is a closed magnetic path formed by the secondary coil.

In the present invention, the magnetic path formed by the primary coil generated by the current flowing from the control power supply differs from the magnetic path formed by the secondary coil generated by the current flowing through the discharge lamp. No voltage is induced in the primary coil. Further, by controlling the current flowing through the primary coil, the magnetic state of the iron core changes, and the inductance on the secondary coil side can be changed. Therefore, dimming of the high-pressure discharge lamp is enabled by one transformer.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a dimming transformer according to the present invention will be described below with reference to FIGS. FIG. 1 is a perspective view showing a configuration of a dimming transformer according to an embodiment, and FIG. 2 is a circuit diagram of a high-frequency lighting device using the dimming transformer according to the present invention. In FIG. 2, FIG.
The same parts as those described above are denoted by the same reference numerals, and redundant description will be omitted.

In FIG. 1, T4 is a dimming transformer, 1
1 is an iron core, L11 is a primary coil, and L12 is a secondary coil. The iron core 11 is a core 12 around which the primary coil L11 is wound.
And an iron core 13 around which the secondary coil L12 is wound. The iron core 12 is a flat yoke 12a.
The first to fourth leg iron portions 12b, 12c, 12
d, 12e are formed so as to protrude.
Are formed so that first to fourth leg portions 13b, 13c, 13d and 13e located at the four corners of the yoke 13a protrude. In this embodiment, the leg portions 13c and 13c are formed.
d and 13b and 3e are integrally formed in a U-shape.

The leg iron portions 12b and 12 of the iron core 12 are
c, 12d, 12e and each leg 13b, 13 of the iron core 13
The iron core 12 and the iron core 13 are joined by facing c, 13d, and 13e, respectively. The primary coil L11 is wound over each leg 12b and 12c of the iron core 12,
The secondary coil L12 is composed of the legs 13c and 13d of the iron core 13.
It is wound over.

The magnetic flux φ1 generated by the primary coil L11
Is a part of the leg iron part 12b, the leg iron part 13b, the yoke 13
a, a leg iron part 13e, a leg iron part 12e, and a yoke 12a.
c, a yoke 13a, a leg 13d, a leg 12d, and a yoke 12a. Also, the secondary coil L12
Of the magnetic flux φ2 generated by the iron part 13c, the iron part 12c, the yoke 12a, the iron part 12b, and the iron part 13c.
b, passes through a magnetic path composed of the yoke 13a, and the other part is a leg iron portion 13d, a leg iron portion 12d, a yoke 12a, a leg iron portion 12
e, a leg 13e and a yoke 13a.

Therefore, the magnetic flux φ1 generated by the primary coil L11 and the secondary coil L12 do not interlink, and the magnetic flux φ2 generated by the secondary coil L12 and the magnetic flux φ2
The primary coil L11 is not linked with the primary coil L11.
No voltage is induced at 11 by the secondary coil L12. However, the iron core 11 can be magnetically saturated by the current flowing through the primary coil L11, and the inductance of the secondary coil L12 can be reduced.

The dimming transformer T4 thus configured
Is inserted into a lighting circuit including the secondary coil L2 of the oscillation transformer T1 and the discharge lamp 1 as shown in FIG. 2, the primary coil L11 of the transformer T4 is turned on by the control power supply 4, and the secondary coil L13 is turned on. Insert and connect to the circuit. Then, the current flowing through the primary coil L11 is controlled, and the inductance on the secondary coil L13 side is controlled. This controls the lamp current to achieve dimming.

In the above embodiment, the primary coil L
The iron core 12 around which the coil 11 is wound is formed such that the leg iron portions 12b, 12c, 12d and 12e protrude from the four corners of the flat yoke 12a, but is similar to the iron core 13 around which the secondary coil L12 is wound. Legs 12b, 12c and 12d
And 12e may be integrated to form a U-shape. In this case, the iron core 13 around which the secondary coil L12 is wound may have a U-shape or may protrude from each leg. It may be formed. Also, both iron cores may be formed so that each leg iron portion protrudes.

[0019]

As described in detail above, according to the present invention,
Since there is no high voltage induced voltage on the primary coil by the secondary coil connected to the high voltage side, it is not necessary to take measures against this voltage, and the transformer for dimming the discharge lamp is one.
And the circuit configuration is greatly simplified. Therefore, it is possible to reduce the size of the circuit board on which the high-frequency lighting device capable of dimming the high-pressure discharge lamp is mounted, to reduce the time and effort required to mount the circuit board, and to reduce the cost.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a dimming transformer according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a high-frequency lighting device using the dimming transformer according to the present invention.

FIG. 3 is a circuit diagram of a conventional high-frequency lighting device.

FIG. 4 is a perspective view showing a configuration of a conventional dimming transformer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge lamp 2 Inverter 3 Power supply 4 Control power supply 11, 12, 13 Iron core 12a, 13a Yoke 12b-12e Leg iron part 13b-13e Leg iron part L11 Primary coil of dimming transformer L12 Secondary coil of dimming transformer T1 Oscillating transformer T4 Dimming transformer φ1 Magnetic flux (magnetic path) due to primary coil of dimming transformer φ2 Magnetic flux (magnetic path) due to secondary coil of dimming transformer

Claims (2)

[Claims] An iron core having first to fourth legs connected to each other by a yoke, and a primary wound around the first and second legs and connected to a control power supply. A second coil wound around the second and third leg portions and connected to a discharge lamp;
And two closed magnetic paths via a fourth iron part and the second and third iron parts are used as a closed magnetic path of the primary coil, and the second and first iron parts and the third iron part are connected to each other. And a dimming transformer, wherein two closed magnetic paths via the fourth leg portion are formed as closed magnetic paths by the secondary coil. 2. The method according to claim 1, wherein at least one of the first and second leg iron portions on the side where the primary coil is wound or the second and third leg iron portions on the side where the secondary coil is wound is formed. The light control transformer according to claim 1, wherein the transformer is formed integrally.