JPH08241698A - External electrode type fluorescent discharge tube - Google Patents

Abstract

PURPOSE: To generate stable visible light and ultraviolet rays by furnishing the first electrode in the form of band or wire on the outer surface of a bulb as stretching in its axial direction, and providing a pair of band- or wire-shaped second electrodes on the outer surface of the bulb as stretching along its axis in positions at equal distance on both sides from the first electrode. CONSTITUTION: The first electrode 6 in the form of band or wire is furnished along the axis of a bulb 1 which is coated on the inner surface with a fluorescent coating material, while a pair of band- or wire-shaped second electrodes 7, 8 are provided on both sides of the electrode 6 on the outer surface of the bulb 1 along its axis in positions at equal distance from the electrode 6. It is preferable that the phosphor substance is removed from the inner surface of the bulb 1 located between the opposing edges 102, 103 of the electrodes 7, 8 and instead an aperture 13 is furnished. The high frequency current from a high frequency power supply 4 flows to the electrodes 7, 8 upon being diverged from the electrode 6 into a left and a right discharge path 11, 12. From the effective light emission surface 9, a part of striation with unstable electric discharge will scarcely be seen. Provision of an electric circuit element between the electrode 6 and the ones 7, 8 generates a further stabilized electric discharging.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external electrode type fluorescent discharge tube for illuminating originals used in information equipment such as facsimiles, copying machines and image readers, and in backlight devices for liquid crystal display panels. Hereinafter referred to as a fluorescent lamp or simply a lamp).

[0002]

2. Description of the Related Art In some fluorescent lamps used as a light source of OA equipment, a backlight of a display device, etc., discharge is maintained by a pair of external electrodes formed on the outer wall of a bulb. Referring to the drawings, FIG. 1 is an explanatory view of a lamp and a power supply, and FIG. 2 is an explanatory view of a cross section taken along the line AA of the lamp.
A pair of external electrodes 2, which are circumferentially spaced from each other on the outer surface of the
3 is provided, and these external electrodes 2 and 3 are connected to a high frequency power source 4. The external electrodes 2 and 3 are formed in a strip shape along the axial direction of the valve by a metal tape such as an aluminum tape and a copper tape, or a conductive paint such as a silver paste. The inner surface of the bulb 1 is coated with a phosphor substance 5. Some of the bulbs contain only a rare gas such as xenon, or some contain a predetermined amount of mercury and a rare gas. is there.

In such a lamp, when a high frequency current is passed from the high frequency power source 4 between the external electrodes 2 and 3, the bulb 1
A discharge 10 is generated inside, and the rare gas or mercury is ionized and excited to emit ultraviolet rays, which are converted into visible light by the phosphor substance 5 and emitted to the outside.

[0004]

The high-frequency current generated by the external electrodes 2 and 3 is caused by a variation in the contact between the glass forming the bulb and the external electrode, a variation in the thickness of the glass tube, and a small amount of the high-frequency current. Due to a change or the like, the discharge 10 may become in a striped pattern along the effective light emitting surface 9 and become in an unstable state, and in particular, it becomes more remarkable as the high-frequency current decreases. The unstable discharge 10 also affects the visible light emitted from the phosphor substance 5, and the visible light emitted from the effective light emitting surface 9 also becomes striped and becomes unstable.

Such a phenomenon causes a problem that information cannot be accurately transmitted in a document illumination used in an information device such as a facsimile, a copying machine or an image reader, and a backlight device of a liquid crystal display panel or the like. If it is used for, there will be problems such as screen shaking and flickering.

The present invention has been made in view of such circumstances, and an object thereof is to provide an external electrode type fluorescent discharge tube having a structure capable of obtaining stable visible light and / or ultraviolet light by an external electrode system. It is what

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an external electrode type fluorescent discharge tube with a linear or strip-shaped first electrode on the outer surface of a tubular bulb in the axial direction of the bulb. This is achieved by providing a pair of linear or strip-shaped second electrodes at equal intervals from the first electrode along the valve axial direction on the outer surface of the valve.

[0008]

According to the present invention, since the high frequency current flows stably, the visible light emitted from the fluorescent lamp can also be emitted stably. Further, more stable visible light can be obtained by adjusting the electrical characteristics such as the capacitance of the capacitor between the high voltage side and the ground voltage side.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. 3 is an explanatory view of a lamp and a power source of the present invention, FIG. 4 is an explanatory view of an AA cross section of the lamp of the present invention, in which 1 is a bulb whose both ends 100 and 101 are closed,
The inner surface of the bulb 1 is coated with a phosphor substance, and the edges 102 of the pair of second electrodes 7 and 8 facing each other,
The phosphor material on the inner surface of the bulb located between 103 is removed and an aperture 13 is provided. First electrode 6
Is a strip-shaped electrode provided along the valve axial direction of the valve 1, and the pair of second electrodes 7 and 8 is provided as a pair along the valve axial direction on the outer surface of the valve on both sides of the first electrode 6. It is a strip-shaped electrode and is provided at positions equidistant from the electrode 6. The electrodes 6, 7 and 8 are formed of a metal tape such as an aluminum tape or a copper tape, or a conductive paint such as a silver paste. Here, the edge 102 of the electrode 7 and the edge 103 of the electrode 8 are preferably arranged along the edge 104 of the opening angle of the aperture 13 determined by the removal of the phosphor substance. The front side of the electrode 6 is an effective light emitting surface 9.

In this arrangement, as shown in FIG. 4, the high frequency power source 4 to the first electrode 6 to the second electrodes 7 and 8 are arranged.
When a high-frequency current is applied to the electrode 6, the high-frequency current flowing from the electrode 6, for example, flows to the pair of second electrodes 7 and 8 provided at equally spaced positions on the left and right of the valve 1 when viewed from the electrode 6, and at this time The flow path of is divided into the left and right from the electrode 6, and flows to the electrodes 7 and 8 through the discharge paths 11 and 12.

In the lamp which discharges in this way, when viewed from the effective light emitting surface 9, almost no unstable striped pattern portion of the discharge can be seen, and stable visible light can be emitted. Also,
As shown in FIG. 3, it is possible to obtain a more stable discharge by setting an electric circuit element such as a capacitor 14 and a resistor 15 at arbitrary values between the first electrode 6 and the second electrodes 7 and 8. It was possible to obtain a stable discharge so that the striped discharge could not be seen at any angle. That is, it is advisable to provide an electric circuit element such as a capacitor or a resistor on the output side of the high frequency power supply as needed.

FIG. 5 is a luminance stability characteristic diagram of the effective light emitting surface 9 when lighting is performed by the conventional discharge method shown in FIG.
FIG. 3 shows a luminance stability characteristic diagram of the effective light emitting surface 9 when lighting is performed by the discharge method of the present invention shown in FIG. This FIG. 5 and FIG.
Comparing the characteristics of the above, the conventional discharge method produces an optical ripple of about ± 6%, whereas the discharge method of the present invention produces almost no optical ripple due to the brightness measurement.
%It has become.

[0013]

As described above, according to the present invention, it is possible to emit very stable visible light and / or ultraviolet light, and it is used for illuminating an original used in information equipment and a backlight device for a liquid crystal display panel. When used for such purposes, it becomes possible to provide stable light.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a conventional fluorescent lamp and a power supply.

FIG. 2 is an explanatory view of an AA cross section of a conventional fluorescent lamp.

FIG. 3 is an explanatory diagram of an embodiment of a fluorescent lamp and a power supply of the present invention.

FIG. 4 is an explanatory view of an AA cross section of the fluorescent lamp of the present invention.

FIG. 5 is a luminance stability characteristic diagram of a conventional fluorescent lamp and a power supply.

FIG. 6 is a luminance stability characteristic diagram of the fluorescent lamp and the power source of the present invention.

[Explanation of symbols]

 1 Tube type bulb 2,3 External electrode 4 High frequency power source 5 Phosphor substance 6 First electrode 7,8 Second electrode 9 Effective light emitting surface 13 Aperture

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toyohiko Kumada 1194 Sado, Bessho-cho, Himeji-shi, Hyogo Ushio Electric Co., Ltd.

Claims (5)

[Claims] 1. He, Ne, Ar,
In a fluorescent discharge tube in which a predetermined amount of at least one kind of rare gas such as Xe or Kr is sealed and sealed, and the inner surface of the bulb is coated with a phosphor material, a linear or strip-shaped first electrode on the outer surface of the bulb in the axial direction of the bulb External electrode type characterized in that a pair of linear or strip-shaped second electrodes are provided at positions equidistant from the first electrode along the valve axial direction on the outer surface of the valve on both sides of this electrode. Fluorescent discharge tube. 2. The high frequency voltage applied between the first electrode and the second electrode is supplied from a power source composed of a high frequency oscillator and a step-up transformer composed of, for example, a transistor or a field effect transistor. Claim 1
The external electrode type fluorescent discharge tube according to 1. 3. The external electrode type fluorescent discharge tube according to claim 2, wherein an electric circuit element such as a capacitor or a resistor is connected to the output side of the high frequency power source. 4. The external electrode type fluorescent discharge tube according to claim 1, wherein mercury vapor is sealed inside the bulb. 5. The phosphor material on the inner surface of the bulb located between the edges of the pair of second electrodes facing each other is removed to provide an aperture. The external electrode type fluorescent discharge tube according to item 4.