JPH05273936A - Discharge lighting circuit - Google Patents

Abstract

PURPOSE:To control lighting with an optimum and the minimum voltage for a discharge path by providing a power source in each discharge path having a different current/voltage characteristic from each other. CONSTITUTION:Discharge tubes LR, LG, LB are used as color discharge tubes corresponding to red, green and blue, respectively. The respective discharge tubes LR, LG, LB are connected to the constant current control circuits 281-283 and given with voltages VB1-VB3 different from each other from power supplies 291-293 through the respective constant current control circuits 281-283. Respective operating voltages are required to be 30V, 33V, 28V based on the current/voltage characteristics of the respective discharge tubes LR, LG, LB and, when the sum of the operating voltages of the constant current control circuits 281-283 and a voltage width due to the voltage dispersion of the respective discharge tubes LR, LG, LB is estimated to be the amount of 10V, voltages VB1, VB2 VB3 become 40V, 43V, 38V, respectively. In such a constitution, voltages are applied on the respective discharge tubes LR, LG, LB, the irreducible minimum lighting control is realized and the heat loss is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting circuit such as a DC lighting discharge tube (hereinafter, simply referred to as a discharge tube) used in a large-sized image display device installed in a baseball field, a racetrack, etc. Is.

[0002]

2. Description of the Related Art As shown in FIG. 4, a large-sized image display device has a frame 1 on which a plurality of display units 2 are arranged in a matrix to form a display screen.

Details of the display unit 2 are shown in FIG. The surface plate 3 is formed with holes in a matrix shape, and the head of the discharge tube 4 is provided so as to project from the holes. Discharge tube 4
The base portion of the holder is engaged with the holder 5, and a circuit for controlling the lighting of the discharge tube 4 is provided in the case 6 behind the holder 5. On the back surface of the case 6, there are provided connectors and the like connected to the lines leading to each circuit.

A circuit for controlling lighting is constructed, for example, as shown in FIG. That is, the video signal is the terminal 21
The signal arrives at the A / D converter 22 via, is converted into a digital signal, and is sent to the signal processing unit 23. On the other hand, a synchronization signal synchronized with the video signal is given to the timing pulse generation circuit 25 via the terminal 24, and a pulse having a predetermined frequency synchronized with the video signal is created. This pulse is given to the signal processing unit 23, where the digital signal is converted into data, and at a speed corresponding to the pulse, for example, the blinking control unit 2 provided corresponding to each display unit 2.
Sent to 6. The blinking control unit 26 performs blinking control on each discharge tube by pulse width control based on the digital data, and gradation control is performed on each discharge tube.

Conventionally, the control signal related to the above blinking control (gradation control) is given to the terminal 27 of the discharge lighting circuit shown in FIG. Cathode discharge tube L - The de power supply voltage V _F of the filament heating is applied, the heating has been made.
A DC voltage V _B is applied to the discharge tube L from a power supply 29 via a constant current control circuit 28. Constant voltage control circuit 28
The resistor _{R 1} transistor _{Q 2} to which is connected to the emitter of the base - Zener between scan and the resistance _{R 1} - diode - connects the de ZD, the Zener voltage _{V ZD,} resistance _R 1 of the resistor _{R 1,}
Base-emitter voltage V _BE (Q
1) is a constant value and V _ZD = I _L × R ₁ + V _BE (Q ₁ ) is used to make the constant current I _L flow in the discharge tube L. Control signal S arriving at terminal 27
Controls the lighting of the discharge tube L by turning on / off the transistor Q ₂ via the resistor R ₃ to control the on / off of the transistor Q ₁ .

This circuit acts as a variable resistor,
When a current flows through this, heat loss occurs. This loss can be suppressed to a small range on condition that the power supply voltage is low and the difference with the voltage of the discharge tube during discharge is small.

[Problems to be Solved by the Invention]

However, in the above circuit, it is necessary to consider variations in the voltage characteristics of the discharge tube. That is,
As the power supply voltage V _B, it is necessary to adopt a voltage obtained by adding the maximum voltage in the variation range among the operating voltages of the discharge tube and the minimum operating voltage of the constant current control circuit. Therefore, if the circuit of FIG. 7 is applied to the discharge tube (discharge path) of the color display device as it is, it is adjusted to the maximum voltage even though the operating voltage is different for each color discharge tube, resulting in heat loss. There was a problem that it was generated unnecessarily and was inefficient.

The present invention has been made to solve the above problems, and its purpose is to perform discharge lighting of a device having discharge paths having different current-voltage characteristics, such as a large color display device. An object of the present invention is to provide a discharge lighting circuit that can be efficiently performed.

[0009]

Therefore, in the present invention, in a discharge lighting circuit for performing discharge lighting on a plurality of discharge paths having different current-voltage characteristics, a constant current control for supplying a predetermined current to each of the discharge paths. A discharge lighting circuit is configured by including a circuit and a power supply unit that gives different voltages corresponding to the current-voltage characteristics of the discharge paths via the constant current control circuit.

[0010]

According to the above construction, a power source is prepared for each discharge path having different current-voltage characteristics, and lighting control can be performed at an optimum voltage for that discharge path.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a discharge lighting circuit according to an embodiment of the present invention. Discharge tube _{L R, L G, L B} are each color - the discharge tube, red, green, corresponding to blue. FIG. 2 shows the current-voltage characteristics of the discharge tubes L _R , L _G , and L _B. That shows that the discharge tube _{L G} to stream 10 mA, it is necessary operating voltage of 33V. Further, it is shown that an operating voltage of 30 V is required to flow 15 mA in the discharge tube L _R. Furthermore, it is shown that an operating voltage of 28 V is required to flow 20 mA in the discharge tube L _B.

Therefore, in this embodiment, the discharge tubes L _R , L _G ,
Each of the L _B has the same configuration as that shown in FIG. 7, and the constant current control circuits 28 ₁ and 28 that flow the current shown in FIG.
₂ and 28 ₃ are connected to each other, and the constant current control circuits 28 ₁ and 28 ₃ are connected.
_2, 28 power source ₂₉ 1 through each of _3, 29 2, 29 ₃
To provide different voltages V _B1 , V _B2 , and V _B3 . Here, the operating voltage of the constant current control circuits 28 ₁ , 28 ₂ , 28 _{3 and} the voltage width due to the variation of each discharge tube are 10 V in total.
Then, by adding the respective operating voltages of the discharge tubes L _R , L _G , and L _B of FIG. 2, the voltages V _B1 , V _B2 , and V _B3 become 40 V, 43 V, and 38 V, respectively. Other configurations are the same as those in FIG. 7.

With the above structure, a voltage is applied to each of the discharge tubes L _R , L _G , and L _B , and lighting control is performed with a minimum required voltage. Therefore, heat loss is also small.

In the above embodiment, the case where the discharge tube is provided with a single discharge element (discharge path) has been described, but the present invention is effective even when the discharge tube includes a plurality of discharge elements. is there. That is, in the discharge tube, as shown in FIG. 3, one cathode K and a plurality of anodes B are provided in a single tube.
Although there are those provided with R, G ₁ and G ₂ , the present invention is also applicable to the case where such a plurality of discharge paths 31 to 34 are provided.

[0015]

As described above, according to the present invention,
A power supply is prepared for each discharge path having different current-voltage characteristics, and since the voltage of this power supply is different, lighting control can be performed at the optimum and minimum voltage for that discharge path. For this reason, efficient power consumption is achieved, and sufficient lighting control is performed for each discharge path.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a discharge lighting circuit according to an embodiment of the present invention.

2 is a diagram showing current-voltage characteristics of each discharge tube used in the embodiment of FIG.

FIG. 3 is a configuration diagram of a discharge tube that can be used in an embodiment of the present invention.

FIG. 4 is a perspective view of a large image display device.

FIG. 5 is a perspective view of a main part configuration of a large-sized image display device.

FIG. 6 is a block diagram of a lighting control circuit of a discharge tube used in a large-sized image display device.

FIG. 7 is a configuration diagram of a conventional discharge lighting circuit.

[Explanation of symbols]

28 _{1, 28} 2, 28 ₃ constant current control circuit 29 _{1, 29} 2, 29 ₃ power S _{1, S} 2, _{S 3} terminal _{L R,} L G, L _B
Discharge tube

Claims (3)

[Claims] 1. A discharge lighting circuit for performing discharge lighting for a plurality of discharge paths having different current-voltage characteristics, a constant current control circuit for supplying a predetermined current to each of the discharge paths, and each of the discharge paths, A discharge lighting circuit, comprising: a power supply section that applies different voltages corresponding to the current-voltage characteristics through the constant current control circuit. 2. The discharge lighting circuit according to claim 1, wherein the power supply unit outputs a voltage obtained by adding an operating voltage of the constant current control circuit and a discharge lighting voltage of a corresponding discharge path. 3. The discharge path is provided in plural within a single discharge lighting tube.
The discharge lighting circuit described.