JPS60254597A - Circuit 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 (Field of the Invention) The present invention relates to a discharge lamp lighting circuit using a direct current lighting method, and more particularly to a discharge lamp lighting circuit suitable for use in a device for individually dimming a plurality of discharge lamps, such as a display device. .

(Background of the Invention) Conventionally, picture elements made of light sources such as incandescent lamps, fluorescent lamps, and CRTs have been used as display devices for scoreboards, various displays, and outdoor advertisements in baseball stadiums, stadiums, amusement parks, etc. It is known that a display surface is constructed by arranging a large number of such elements in a matrix.

When a discharge lamp (lamp) is used as a picture element in such a display device, it is necessary to perform dimming lighting based on a video signal, but for this purpose, it is easy to use a switching element such as a transistor for each lamp. It is desirable to use direct current for lighting.

However, if an attempt is made to directly light a discharge lamp with a DC power source, a resistance must be used as a current limiting element of the discharge lamp, which is a negative resistance, resulting in a large loss. In addition, using a bulk power supply that generates high frequency output from a DC power supply using a high frequency generator such as an inverter,
A lighting circuit is known in which this high-frequency output is limited by an inductor and is full-wave rectified by a diode bridge to light the discharge lamp. But in this case,
Although the current limiting element becomes an inductor and the above loss problem is solved, when using multiple such lighting circuits,
If a common potential point cannot be obtained between each lighting circuit, a power supply for filament preheating or a DC power supply for the dimming control circuit must be provided for each lighting circuit, or a transformer that connects the dimming switch element and the dimming control circuit, etc. , which has the disadvantage of complicating the circuit configuration and increasing the size of the circuit. Furthermore, a lighting circuit is also known in which a discharge lamp is lit with a current obtained by current-limiting and half-wave rectifying the high-frequency output from the above-mentioned -slide power source using a series circuit of an inductor and a diode. According to this lighting circuit, the above problems of loss and common potential point are solved. However, in this case, the power transformer and the current-limiting inductor become biased due to leakage current, which is particularly disadvantageous in that the power transformer becomes larger.

(Object of the invention) The object of the present invention is to solve the problems of the conventional type described above.
In a DC lighting discharge lamp lighting circuit that lights multiple discharge lamps with a half-wave rectified output in which the AC output supplied via the power transformer is limited and rectified using an inductor and a diode, biased magnetism in the power transformer is reduced. By doing so, the power transformer and therefore the circuit can be made smaller.

(Structure of the Invention) In order to achieve the above object, the present invention includes a power transformer,
A series circuit consisting of a plurality of DC lighting discharge lamps, a first inductor and a first diode connected to one end of a secondary winding of the power transformer, and an AC output supplied through the power transformer. In a DC lighting discharge lamp lighting circuit comprising a first half-wave rectifier circuit that performs half-wave rectification and supplies the main discharge current of the discharge lamp, the first half-wave rectifier circuit is connected to one end of the secondary winding of the power transformer. It is composed of a series circuit of a second inductor and a second diode, and generates a half-wave rectified output having a polarity opposite to the main discharge current of the discharge lamp from the AC output, so that a filament current of a part of the plurality of discharge lamps is generated. It is characterized by having a second half-wave rectifier circuit that supplies a second half-wave rectifier circuit.

(Explanation of Examples) Hereinafter, the present invention will be explained in detail using the drawings.

The attached drawing shows the configuration of a discharge lamp lighting circuit according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a high frequency generator such as an AC power source, such as an inverter, and 2 denotes a power transformer, which is also used as an output transformer if the AC N source 1 is an inverter or the like.

3.7 is an inductor, 4.6 is a diode, and 5 is a discharge lamp.

A half-wave rectifier circuit consisting of an inductor 3 and a diode 4 supplies a lamp current to the main discharge circuit of the lamp 5 in a downward direction in the figure. A half-wave rectifier circuit consisting of a diode 6 and an inductor 7 supplies a filament current to the filament circuit of the lamp 5 upward in the figure.

Here, the total number of lamps is N, the main discharge current (lamp current)
, Jfa is the filament current in the opposite direction to the main discharge current IL, I fb is the filament current in the same direction as the main discharge current IL, Na is the number of lamps to which the filament current 1fa is supplied, and Na is the number of lamps to which the filament current 1fb is supplied. If the number of lamps to be used is Nb, then in order to eliminate biased magnetization of the power transformer 2, N IL +Nb Ifb=Na Ifa
The direction of the filament current of each lamp should be determined so as to satisfy the following. For example, assuming that the characteristics of each lamp 5 are the same, TL = 0.15 A, If (-1fa =
If I fb ) = 0.3 A, the ratio of the lamp in which the filament current is in the forward direction and the lamp in which the filament current is in the reverse direction may be set so as to satisfy the condition of Na = 3 Nb.

(Scope of Application of the Invention) The present invention is not limited to the above-described embodiments, but can be implemented with appropriate modifications. For example, in the above embodiment, a half-wave rectified output in the forward or reverse direction is supplied to the filaments of all the lamps. For example, Na-N/2 lamps may be supplied with a negative current Ifa in the opposite direction to the main discharge current I, and the remaining lamps may be supplied with an alternating current that is not rectified.

(Effects of the Invention) As described above, according to the present invention, in a discharge lamp lighting circuit using a DC lighting method that lights a discharge lamp using a half-wave rectified output of an AC power source, the filament current in the direction opposite to the main discharge current of the lamp is controlled. Since the supplied φ lamps are appropriately mixed to balance the bidirectional current flowing through the power transformer, the biased magnetic effect of the power transformer can be minimized, and the power transformer and therefore the device can be downsized.

[Brief explanation of drawings]

The accompanying drawing is a circuit diagram of a discharge lamp lighting circuit according to an embodiment of the present invention. 1... AC side L 2... Power transformer, 3.7... Inductor, 4.6.6'... Diode, 5... Discharge lamp. Patent applicant: Toshiba Electric Materials Co., Ltd. Attorney: Attorney Tatsuo Ito Attorney: Tetsuya Ito

Claims (1)

[Claims] 1. A series circuit consisting of a power transformer, a plurality of DC lighting discharge lamps, and a first inductor and a first diode connected to one end of a secondary winding of the power transformer. and a first half-wave rectifier circuit that half-wave rectifies the AC output supplied via the power transformer and supplies the main discharge current of the discharge lamp, wherein the power supply It consists of a series circuit of a second inductor and a second diode connected to one end of the secondary winding of the transformer, and the AC output generates a half-wave rectified output with a polarity opposite to the main discharge current of the discharge lamp. A discharge lamp lighting circuit characterized in that it has a t=6 second half-wave rectifier circuit that supplies part of the filament current to the plurality of discharge lamps. 2. A series circuit consisting of a third inductor and a third diode, which correspond to the second inductor and the second diode, is connected to one end of the secondary winding of the power transformer, and is connected to the output from the AC output. Claim 1, further comprising a third half-wave rectifier circuit that generates a half-wave rectifier output having the same polarity as the main discharge current of the electric lamp and supplies the remaining filament currents of the plurality of discharge lamps. Discharge lamp lighting circuit described in section. 3. The first rectifier circuits are provided in the same number as the discharge lamps to supply the main discharge current to each of the discharge lamps, and the second and third rectifier circuits are provided in the same number as the discharge lamps. Claim 2, wherein the filament current is supplied from each discharge lamp to each discharge lamp.
Discharge lamp lighting circuit described in section.