JPS618842A - Discharge lamp device for display element - Google Patents

Abstract

PURPOSE:To prevent a discharge lamp from going out when its light is reduced, by adding a light control circuit section, which varies an input current, to a high-frequency oscillation circuit which supplies a high-frequency current to a coil, and by providing an auxiliary electrode for continuously causing glow discharge in a bulb when power is applied to the coil. CONSTITUTION:When a high-frequency current caused by the high-frequency output transformer 15 of a high-frequency oscillation circuit 13 flows through a coil 11, a closed-loop magnetic flux along the axis of a core 10 is generated and a high-frequency electric field is produced around the core. At that time, a discharge medium is stimulated to generate ultraviolet rays so that visible rays of light are emitted from a fluorescent film 8. After the visible rays of light are reflected by a light reflection film 7, the rays of light are radiated outwards through a lens 4. When a light control signal is applied to a light control circuit section 16, an input current is increased or decreased to control the quantity of the visible rays of light. An output voltage is applied to the high-frequency output transformer 20 of a high-frequency oscillation circuit 21 so that a high-frequency voltage is produced through a secondary winding 19. The high-frequency voltage is applied between the coil 11 and an auxiliary electrode 17 to cause glow discharge in a bulb 3 to prevent the visible rays of light from vanishing when the input to the coil 11 is reduced to control the quantity of the visible rays of light.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a discharge lamp device for a display element constituting a single pixel in, for example, a color image display device.

[Technical background of the invention]

Conventionally, CRTs, color light bulbs, fluorescent lamps, etc. that emit monochrome lights of red, green, and blue have been known as display elements of this type, but recently the present inventor has developed a method using discharge media such as inert gas and mercury. A magnetic core is housed in a bulb enclosing a magnetic core, and by supplying a high-frequency current to a coil wound around the magnetic core, a high-frequency electromagnetic field is created in the bulb to generate an electric discharge in the bulb, We are trying to use a so-called electrodeless discharge lamp in which this discharge excites a phosphor inside the bulb to emit light.

[Problems with background technology]

By the way, the above-mentioned video display device is a television camera or VTR.
In order to display various images recorded on a screen board on a screen board, each display element constituting a single pixel is dimmed within a range of 0 to 100% according to the image signal.

Therefore, when using an electrodeless discharge lamp as this display element, it is conceivable to add a dimming control circuit section that increases or decreases the input current to the coil to the circuit that supplies the high-frequency current to the coil. If only a dimming control circuit section was provided, there would be a problem in that the light would go out when the light was dimmed.

In other words, this discharge lamp is equivalently
- When considered as a lance, the discharge path generated around the magnetic core can be considered as a one-turn secondary coil, so when the input current is reduced for dimming, the discharge path generated in the secondary coil The voltage applied to the lamp is lower than the discharge voltage. This will lengthen the current rest period from when the phase of the lamp voltage is reversed until the voltage required for re-ignition is reached.
Since the impedance of the lamp becomes higher and a correspondingly higher restriking voltage is required, the lamp goes out and becomes impossible to dim.

[Purpose of the invention]

The present invention was made in view of these circumstances.
An object of the present invention is to provide a discharge lamp device for a display element that can prevent the light from going out during dimming.

(Summary of the Invention) That is, in order to achieve the above object, the present invention adds a dimming control circuit section that varies the input current to the coil to a high frequency oscillation circuit that supplies a high frequency current to the coil, and also The bulb is characterized by being provided with an auxiliary electrode connected to a high-frequency oscillation circuit to constantly generate glow discharge within the bulb when input to the coil.

[Embodiments of the invention]

The present invention will be explained below based on one embodiment shown in the drawings.

Figure 2 shows, for example, a scoreboard at a baseball field or stadium.
-Alternatively, it shows an outline of a large display screen that is used by being built into the wall of a building, and on a substantially rectangular screen board 1, thousands to tens of thousands of discharge lamp devices 2 for display elements are mounted.・are arranged closely in parallel.

Details of each of these discharge lamp devices 2 for display elements are shown in FIG. That is, reference numeral 3 indicates a glass bulb, and this bulb 3 has an elongated hollow cylindrical shape. One end opening of the bulb 3 is closed by a lens 4, and the other end opening is sealed by a stem 5, and a predetermined amount of discharge medium is discharged into the bulb 3 after being exhausted through a thin tube 6. It is filled with mercury and inert gas. Further, a light reflective film 7 such as an alumina coating film is coated on the inner wall surface of the bulb 3, and a phosphor film 8 is overlaid on the light reflective film 7 and on the inner wall surface of the lens 4. is worn and therefore
This glass tube 3 has translucency only at the lens 4 portion, and the outer surface of this lens 4 serves as a light emitting surface 9 for display purposes. Note that a colored filter may be attached to the light emitting surface 9 of this lens 4 if necessary.

Incidentally, such a bulb 3 houses an annular core 10 made of a magnetic material such as ferrite, and a coil 11 is wound around a part of the circumferential surface of the core 10. Both ends of the coil 11 are led inside the valve 3 to the stem 5 side, and are connected to a lead 112 sealed in the stem 5.
．． It is connected to a high frequency oscillation circuit 13 via 12.

This high-frequency oscillation circuit 13 converts the output of a DC power supply 14 into a high-frequency current using a high-frequency quadrature lance 15 and outputs the converted high-frequency current, and this high-frequency current is supplied to the coil 11. This high-frequency oscillation circuit 13 is provided with a dimming control circuit section 16 for varying the input of high-frequency current to the coil 11, and this dimming control circuit section 1G is provided with a predetermined control signal through a video control section (not shown). A dimming signal is input.

Further, an auxiliary electrode 17 is attached to the outer peripheral wall surface of the bulb 3 in the vicinity of the core 10, and this auxiliary electrode 17 constitutes a high-frequency oscillation circuit 21 separate from the high-frequency oscillation circuit 13. Secondary winding 19 of high frequency cadence 20
It is connected to the.

Next, the operation of the above configuration will be explained.

When the high-frequency current generated by the high-frequency cadence 15 of the high-frequency oscillation circuit 13 flows to the coil 11 through the lead wire 12.12, the core 11 around which the coil 11 is wound
passes through the frontage of this core 10, and
A closed loop magnetic flux is generated along the axial direction of the core 10, and as a result, a high frequency electric field is formed around the core 10. The high-frequency electric field excites the discharge medium enclosed in the bulb 3 to generate ultraviolet light, and the ultraviolet light excites the phosphor coating 8 to emit visible light. This visible light is reflected by the light reflecting film 7 and then radiated outward through the lens 4.

On the other hand, the dimming signal from the video control section is transmitted to the dimming control circuit section 16.
When the input current is input to the coil 11, the input current to the coil 11 is adjusted to increase or decrease, and dimming is performed within the range of 0 to 100%. In addition, at the time of this dimming, the output voltage is also applied to the high frequency cadence 20 of another high frequency oscillation circuit 21, so the high frequency voltage generated in the secondary winding 1i119 is transmitted between the auxiliary electrode 17 and the coil 11. This causes a G, O discharge in the bulb 3. The above high frequency voltage is applied to the coil 11.
Even when the supply of high-frequency current to the auxiliary tube t is stopped,
remains applied to ft17, and therefore,
Glow discharge continues to be generated in the bulb 3 even during dimming.

According to such a display element discharge lamp 2..., since glow discharge is constantly generated in the bulb 3 when inputted to the coil 11, the restriking voltage can be suppressed to a low level.
Even when the input to the coil 11 begins to decrease due to dimming, a main discharge is easily initiated within the bulb 3. therefore,
It is possible to prevent fading during dimming from 0 to 100%. Furthermore, the auxiliary electrode 17 should be installed near the magnetic core 10 in order to ensure sufficient dimming even under adverse conditions such as a drop in power supply voltage or low outside temperature. is desirable. In particular, the auxiliary electrode 17
The closer the magnetic core 10 is to the magnetic core 10, the lower the rate of occurrence of extinction under adverse conditions.

In the present invention, the auxiliary electrode is not limited to being provided on the outer wall surface of the bulb, but may be provided on the inner wall surface of the bulb as the case may be.

〔Effect of the invention〕

According to the present invention described in detail above, glow discharge is constantly generated in the bulb when input to the coil, so the fractional ignition voltage can be suppressed to a low level. Even when the input decreases, it is possible to easily generate a main discharge within the bulb, and there is an advantage in that it is possible to prevent a rise during dimming from 0 to 100%.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a sectional view of a discharge lamp device for a display element, and FIG. 2 is a schematic configuration diagram of a display screen. 3... Bulb, 8... Fluorescent coating, 10... Core, 11... Coil, 13.21... High frequency oscillation circuit, 16... Dimming control circuit section, 17 ...Auxiliary electrode.

Claims (3)

[Claims] (1) A bulb with a discharge medium sealed inside and a phosphor film coated on the inner wall surface, a magnetic core housed in the bulb, and a coil wound around the magnetic core. and a high-frequency oscillation circuit that supplies a high-frequency current to the coil, the display element discharge lamp device being used for lighting with the bulb facing the display direction, the high-frequency oscillation circuit having an input current to the coil. A discharge lamp device for a display element, characterized in that the bulb is provided with a dimming control circuit section for varying the brightness, and an auxiliary electrode connected to a high frequency oscillation circuit to constantly generate glow discharge in the bulb. (2) The discharge lamp device for a display element according to claim (1), wherein the auxiliary electrode is provided near the magnetic core. (3) The discharge lamp device for a display element according to claim (2), wherein the auxiliary electrode is a proximal conductor attached to the outer wall of the bulb.