JPH08273591A - Cold-cathode discharge lamp, lighting device thereof, and lighting system, backlight, and liquid-crystal display device using same - Google Patents

Abstract

PURPOSE: To provide a cold-cathode discharge lamp which can prevent interference between a cold cathode and a bulb and has an extended life, a lighting device thereof, a lighting system, a backlight, and a liquid-crystal display device. CONSTITUTION: A cold cathode 12, comprising an electrode sleeve 14 the end of which is crushed, flattened and thereby joined to an electrode shaft 13, is provided at the end of a bulb 10, and when the bore of the bulb 10 is Dmm and the flattened width of the flat end 14a of the electrode sleeve is (w) mm, D-(w)>=0.2mm. With the relation of D-(w)-0.2mm between the bore Dmm of the bulb and the width (w)mm of the flat end of the electrode sleeve, a gap is secured between the inner surface of the bulb and the electrode sleeve, interference between the bulb and the electrode sleeve is prevented to facilitate insertion of an electrode, and the rate at which the electrode material clings to the bulb wall is reduced to keep the bulb from the heat of the electrode so as to enhance life characteristic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold cathode discharge lamp, a lighting device for the same, an illuminating device using the same, a backlight and a liquid crystal display device.

[0002]

2. Description of the Related Art A cold cathode fluorescent lamp is used as a backlight light source for a small liquid crystal display device. This type of cold cathode fluorescent lamp has a structure in which the surface area of the electrode is relatively large and a large amount of electrons are emitted.
The electrode structure is constructed by joining a flat or mountain-shaped electrode plate or a cylindrical electrode sleeve to the tip of the electrode shaft.
Among them, the structure using the electrode sleeve has advantages that the surface area can be increased and the mercury alloy and the getter material can be held inside the sleeve.

Such a cold cathode employs a structure in which the end portion of the electrode sleeve is crushed to bring the end portion into pressure contact with the electrode shaft, and the electrode sleeve is welded to the electrode shaft in this pressure contact state.

[0004]

However, in the case of the structure in which the end portion of the electrode sleeve is crushed and pressed against the electrode shaft, the crushed end portion is deformed into a flat shape. If the width of the flat portion is increased, the flat portion is likely to come into contact with the inner surface of the valve, which hinders the electrode insertion work.

Particularly in recent liquid crystal display devices, it is desired to improve the brightness of the liquid crystal screen, and for this purpose, it is necessary to increase the brightness of the cold cathode fluorescent lamp as the light source. In order to increase the brightness of the lamp, it is effective to reduce the bulb diameter.However, if the bulb is made thin, the flat part approaches the bulb wall in the case of the cold cathode having the above structure, and it is easy to interfere. Occurs. Further, when the cold cathode approaches the bulb wall, the electrode material is likely to adhere to the bulb wall, which not only causes blackening, but also causes a discharge between the opposing electrodes.

If the electrode sleeve is made thin in order to prevent such a problem, there are disadvantages that the amount of electron emission is reduced, the efficiency is reduced, and the life is shortened.
The present invention has been made based on such a situation, and an object thereof is a cold cathode discharge lamp capable of preventing interference between a cold cathode and a bulb and having improved life characteristics, a lighting device thereof, and a lighting device thereof. It is intended to provide a lighting device, a backlight, and a liquid crystal display device used.

[0007]

According to a first aspect of the present invention, there is provided a valve in which an ionizing medium is enclosed; and an electrode shaft and an electrode sleeve provided at the end of the valve, the end of the electrode sleeve being A cold cathode in which the end portions are pressed against the electrode shaft by being crushed to join the electrode sleeve and the electrode shaft; the inner diameter of the bulb is Dmm, and the electrode sleeve is crushed to be flat. In the cold cathode discharge lamp, when the width dimension in the flattened direction is wmm, Dw ≧ 0.2 mm.

Here, the cold cathode discharge lamp includes a cold cathode fluorescent lamp and a cold cathode rare gas discharge lamp. The invention of claim 2 is characterized in that, when the inner diameter of the electrode sleeve is d ₁ mm and the outer diameter of the electrode shaft is d ₂ mm, d ₁ −d ₂ ≦ 0.3 mm. It is a cold cathode discharge lamp.

According to a third aspect of the invention, the inner diameter D of the valve is 3.
It is 0 mm or less, It is a cold cathode discharge lamp of Claim 1 or Claim 2 characterized by the above-mentioned. The invention of claim 4 is the cold cathode discharge lamp according to any one of claims 1 to 3, characterized in that at least an amalgam is held in the electrode sleeve.

The invention of claim 5 is characterized by comprising the cold cathode discharge lamp according to any one of claims 1 to 4; and a lighting circuit for lighting the cold cathode discharge lamp. It is a lighting device for a cold cathode discharge lamp.

The invention of claim 6 comprises the cold cathode discharge lamp according to any one of claims 1 to 4, and a lighting fixture to which the cold cathode discharge lamp is attached. Lighting device.

The invention of claim 7 is the cold cathode discharge lamp according to any one of claims 1 to 4, a reflector for reflecting the light emitted from the cold cathode discharge lamp, and this reflector. And a diffuse transmission means for diffusing and transmitting the light reflected by.

An eighth aspect of the present invention is a liquid crystal display device comprising: the backlight according to the sixth aspect; and a liquid crystal display plate illuminated by the backlight.

[0014]

According to the invention of claim 1, the inner diameter of the valve is set to Dm.
m, if the width of the flattened flattened direction of the electrode sleeve in the flattened direction is wmm, Dw ≧ 0.2mm, so a small gap should be secured between the valve inner surface and the electrode sleeve. Therefore, interference between the valve and the electrode sleeve can be prevented, and the electrode can be easily inserted. In addition, since the gap is secured between the valve and the electrode sleeve,
The ratio of the electrode substance adhering to the bulb wall is reduced, and the bulb is less likely to receive heat from the electrode, so that the life characteristics are improved.

According to the second aspect of the invention, when the inner diameter of the electrode sleeve is d ₁ mm and the outer diameter of the electrode shaft is d ₂ mm, d ₁
Since −d ₂ ≦ 0.3 mm, the flat width w of the crushed end of the electrode sleeve can be reduced.
Therefore, the interference between the valve and the electrode sleeve can be prevented.

According to the invention of claim 3, the inner diameter D of the valve is
Is 3.0 mm or less, which is effective in improving the brightness. However, since the valve becomes relatively thin, interference between the valve and the electrode sleeve is likely to occur, but Dw ≧ 0.2 mm
By doing so, it is possible to avoid interference between the valve and the electrode despite the valve becoming thinner.

According to the fourth aspect of the invention, since at least the amalgam is held in the electrode sleeve, a fixed amount of mercury can be easily enclosed. According to the inventions of claims 5 to 7, it is possible to provide a lighting device, a lighting device, a backlight, and a liquid crystal display device, which make the most of the advantages of the cold cathode discharge lamp.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings. FIG. 1 shows the structure of a lighting device for a cold cathode discharge lamp including a cold cathode fluorescent lamp 1 and a high-frequency lighting circuit device 2 for lighting the lamp, FIG. 2 shows the structure of the cold cathode, and FIG. 3 shows this cold cathode. An exploded perspective view of a liquid crystal display device using a discharge lamp device is shown, and FIG. 4 is a sectional view thereof.

The cold cathode fluorescent lamp 1 shown in FIG.
Is 3.0 mm or less, and in this embodiment, there is an elongated bulb 10 having an inner diameter D = 2.0 mm (outer diameter 2.6 mm) and a total length of 200 mm. This bulb 10 is made of lead glass.
On the inner surface of the bulb 10, a phosphor layer 1 made of a phosphor that is excited by ultraviolet rays having a wavelength of 185 nm and 254 nm emitted by mercury to emit visible light, for example, a three-wavelength emitting phosphor.
1 is formed. The three-wavelength emission type phosphor is, for example,
Y ₂ O ₃ : Eu as a red phosphor, L as a green phosphor
aPO _4: BaMgAl Ce, Tb, as blue phosphors
₁₄ O ₂₃ : Eu is used.

Cold cathodes 12, 12 are sealed at both ends in the longitudinal direction of the bulb 10. Each of the cold cathodes 12, 12 is made of nickel Ni or the like, and has a cylindrical electrode body, that is, the electrode sleeve 1, on the electrode shaft 13 which also serves as a lead wire.
4 are joined together. The electrode sleeve 14 is formed of a nickel tube, and as shown in FIG. 2, the inside thereof is filled with a mixture 15 of a getter made of an alloy of zirconium Zr and aluminum Al and an amalgam made of mercury and titanium.

The electrode sleeve 14 is joined to the electrode shaft 13 at its end. In this case, the electrode sleeve 14
In order to set the center position of the electrode shaft 13 and the electrode shaft 13 coaxially, the end portion of the electrode sleeve 14 is crushed in the radial direction, and the electrode shaft 13 is held by the end portion 14a which is flatly deformed by this crushing. It is supposed to do. Then, the electrode sleeve 13 and the electrode shaft 13 are spot-welded with the flat end 14a holding the electrode shaft 13 therebetween. Therefore, the flat end 14a of the electrode sleeve 14 is
The dimension outside the original outer diameter of the electrode sleeve 14 in the flat direction is taken as the flat width w, and the valve 1
If the inner diameter of 0 is Dmm, the relationship of Dw ≧ 0.2mm (1) is established. That is, valve 1
When the inner diameter D of 0 is 2.0 mm, the flat width w is restricted to 1.8 mm or less.

The electrode sleeve 14 has an inner diameter d ₁
Is 0.8 mm and the wall thickness t is 0.1 mm, so that the outer diameter of the electrode sleeve 14 is 1.0 mm. The inner diameter d ₁ of the electrode sleeve 14 and the outer diameter d ₂ of the electrode shaft satisfy the relationship of d ₁ −d ₂ ≦ 0.3 mm (2). The outer diameter d ₂ mm is 0.5 mm.

The cold cathode 12 having such a structure is composed of the electrode shaft 1
3 is connected to a sealing wire 16 made of a metal having a thermal expansion coefficient similar to that of glass, for example, a large diameter Dumet wire, and the sealing wire 16 is sealed to a sealing portion 18 at the end of the valve 10. . The sealing wires 16 are connected to external lead wires 17, respectively.

In addition to the mercury released from the amalgam, the valve 10 is filled with a mixed rare gas composed of argon Ar and neon Ne at a predetermined pressure. The filling pressure of the mixed rare gas is about 100 Torr.

Such a cold cathode fluorescent lamp 1 is connected to the high frequency lighting circuit device 2 shown in FIG. The high-frequency lighting circuit device 2 supplies high-frequency power having a frequency of about 50 kHz, and the high-frequency power supplies the cold-cathode fluorescent lamp 1.
Lights up.

The operation of the cold cathode fluorescent lamp lighting device having such a configuration will be described. High frequency lighting circuit feeder 2
More cold cathode fluorescent lamp 1, frequency 50kHz, voltage 1
When a high frequency voltage of about 200 V (rms) is supplied, the cold cathodes 12 and 12 provided at both ends in the cold cathode fluorescent lamp 1 are supplied.
The high-frequency voltage is applied between the cold cathode 1 and the cold cathode 1.
Discharge occurs between 2 and 12. The ionizing medium composed of mercury and a rare gas in the discharge space is ionized and excited by the above discharge, and emits ultraviolet rays. This ultraviolet ray is converted into visible light by the phosphor layer 11, so that the visible light is transmitted to the outside through the wall of the bulb 11.

In the cold cathode fluorescent lamp 1, since the inner diameter D of the bulb is 3.0 mm or less, the brightness is improved. When the inner diameter of the valve 10 is Dmm and the flat width of the flat end portion 14a of the electrode sleeve 14 is wmm, Dw ≧ 0.2.
Since the relationship of mm is satisfied, a gap is secured between the inner surface of the bulb 10 and the electrode sleeve 14. Therefore, when the cold cathode 12 is inserted into the bulb 10, the flat end portion 14a of the electrode sleeve 14 is less likely to contact the inner surface of the bulb 10, and the cold cathode 12 can be easily inserted. In addition, since there is a gap between the inner surface of the bulb 10 and the electrode sleeve 14, the cold cathode 12 does not come too close to the bulb wall, and the electrode substance adheres to the bulb wall to be blackened or the opposite electrode. A defect such as a discharge occurring between and is suppressed.

The dimension of Dw, that is, the valve 10
The larger gap between the inner surface and the flat end portion 14a of the electrode sleeve 14 means that the electrode sleeve 14 is made thinner, which reduces the electron emission amount.
The efficiency is reduced and the life is shortened. For this reason,
Dw is preferably 0.6mm or less (0.6mm
≧ D−w ≧ 0.2 mm).

The lamp 1 has an electrode sleeve 14
If the inner diameter of the electrode shaft 13 is d ₁ mm and the outer diameter of the electrode shaft 13 is d ₂ mm, then d ₁ −d ₂ ≦ 0.3 mm.
The flat width w of the flat portion 14a formed at the end of No. 4 can be reduced. That is, the outer diameter d ₂ of the electrode shaft 13
Needs a certain thickness to flow a certain current,
Since the size of the electrode sleeve 14 is set to the condition of the expression (2) for the electrode shaft 13 as described above, the electrode sleeve 14
Will be regulated relatively thinly. Therefore, when the end portion of the electrode sleeve 14 is crushed, the center positions of the electrode sleeve 14 and the electrode shaft 13 are less likely to shift, and the flatness ratio can be reduced, so that the flat width w of the flat portion 14a is reduced. Therefore, it is possible to prevent interference between the flat portion 14a and the inner surface of the valve.

The electrode sleeve 14 is required to have a large surface area in order to emit a large amount of electrons and promote heat dissipation of the electrode. Therefore, the electrode sleeve 14
If the thickness is too thin, the amount of emitted electrons will decrease and the heat dissipation will deteriorate. From such a viewpoint, d ₁ −d ₂ is 0.
It is desirable that it is 1 mm or more (0.1 mm ≦ d ₁ −d ₂
≦ 0.3 mm).

Further, in the above embodiment, the electrode sleeve 1
Since 4 is filled with the mixture 15 of amalgam and getter, the mercury can be easily enclosed in a fixed amount, the mercury can be enclosed with high precision, and the getter holding structure is simplified.

3 and 4 show an example in which the cold cathode discharge lamp 1 shown in FIG. 1 is used as a light source device of a liquid crystal display device. That is, in FIGS. 3 and 4, 30 is a backlight and 40 is a liquid crystal display panel.

The backlight 30 includes a light guide plate 31, a pair of the cold cathode fluorescent lamps 1 and 1 and reflectors 32 and 32 that surround the fluorescent lamps 1 and 1. The light guide plate 31 is made of acrylic resin or the like. It is formed in a rectangular flat plate shape by a transparent or milky white light transmissive material such as.
The fluorescent lamps 1 and 1 are arranged at both ends of the light guide plate 31 so as to face the end faces of the light guide plate 31. The fluorescent lamps 1 and 1 are the cold cathode fluorescent lamps shown in FIG. 1, and are connected as shown in FIG. 1 to a high frequency lighting circuit device 2 not shown in FIGS. 3 and 4.

Each cold cathode fluorescent lamp 1, 1 is covered with a reflector 32, 32, respectively. These reflectors 32,
Reference numeral 32 is made of metal or resin, and has a substantially gutter shape whose section forms a quadratic curve and extends along the tube axis direction of the cold cathode fluorescent lamps 1, 1. Reflection surfaces 33, 33 are formed on the inner surfaces of the reflectors 32, 32 to reflect the light emitted from the fluorescent lamps 1, 1 and direct the light toward the end surface of the light guide plate 41.

A reflection plate 35 or a reflection sheet is provided on the lower surface of the light guide plate 31, that is, the back surface. The reflection plate 35 reflects the light introduced into the light guide plate 31 and is directed to the upper surface (front surface) side. Tell A light diffusing plate 36 or a light diffusing sheet having a milky white color made of acrylic resin or the like is provided on the upper surface of the light guiding plate 31, and the light diffusing plate 36 diffuses the light emitted from the upper surface of the light guiding plate 31. Control is performed so that a uniform brightness distribution is obtained, and thereby uneven brightness is eliminated.

The backlight 30 is constructed with such a configuration, and the liquid crystal display panel 40 is installed on the front surface of the light diffusion plate 36 of the backlight 30. Therefore, the backlight 30 and the liquid crystal display panel 40 constitute a liquid crystal display device.

In the liquid crystal display device having such a structure, when the cold cathode fluorescent lamps 1 and 1 as the light source are lit at high frequency, the light emitted from the fluorescent lamps 1 and 1 is reflected directly and by the reflectors 32 and 32. The light is reflected by the surfaces 33, 33, faces the end surface of the light guide plate 31, and enters the inside of the light guide plate 31 from this end surface. Inside the light guide plate 31, light travels while repeating total reflection on each surface, and is reflected by the reflection plate 35 provided on the back surface, so that the light is eventually emitted toward the front surface. In this way, the light traveling toward the front surface of the light guide plate 31 is diffused by the light diffusion plate 36, and the diffused light is reflected by the liquid crystal display panel 40.
Illuminate the back of the. Therefore, the liquid crystal display panel 40 is illuminated by the light from the backlight 30, and a predetermined display can be displayed on the front surface.

Such a backlight 30 includes the lamp 1
Since the diameter of the liquid crystal display is reduced and the brightness is improved, the brightness of the liquid crystal display panel 40 is also increased, and the liquid crystal display surface is easy to see. The reflector 32 and the cold cathode fluorescent lamp 1 constitute the lighting device of the present invention, and the reflector 32 corresponds to a lighting fixture.

The present invention is not limited to the above embodiment. That is, in the above embodiment, the valve 10
Cold cathode fluorescent lamp 1 having cold cathodes 12, 12 at both ends of
Although the cold cathode 12 is provided only at one end of the bulb 10 and an external electrode is provided at the other end of the bulb 10, the present invention can be implemented.

In the above embodiment, the cold cathode fluorescent lamp in which the ionizing medium composed of mercury and rare gas is enclosed in the bulb 10 and the phosphor layer 11 is formed on the inner surface of the bulb 10 has been described. The present invention is not limited to this, and it is possible to use a so-called cold cathode xenon discharge lamp in which xenon Xe or a rare gas mainly containing xenon Xe is enclosed in the bulb 10 instead of mercury and a rare gas, and the bulb 10 can be used. The present invention can be implemented even with a discharge lamp in which the phosphor layer 11 is not formed on the inner surface. Furthermore, the cross-sectional shape of the valve may be any of a circular shape, an elliptical shape, and an oval shape.

[0041]

As described above, according to the invention of claim 1, when the inner diameter of the valve is Dmm and the width dimension of the flat end portion of the electrode sleeve is wmm, Dw ≧ 0.2 mm. As a result, a gap is secured between the inner surface of the valve and the electrode sleeve, interference between the valve and the electrode sleeve is prevented, insertion of the electrode is facilitated, and the ratio of electrode substances adhering to the valve wall is reduced. In addition, the bulb is less likely to receive heat from the electrode, and the life characteristics are improved.

According to the second aspect of the invention, when the inner diameter of the electrode sleeve is d ₁ mm and the outer diameter of the electrode shaft is d ₂ mm, d ₁
Since −d ₂ ≦ 0.3 mm, the flat width w of the flat end portion of the electrode sleeve can be reduced, and therefore a gap is secured between the inner surface of the valve and the electrode sleeve. Interference of the electrode sleeve can be prevented.

According to the invention of claim 3, the inner diameter D of the valve is
Is 3.0 mm or less, which is effective in improving the brightness. According to the invention of claim 4, since at least the amalgam is held in the electrode sleeve, the fixed amount of mercury can be easily enclosed, and the enclosed amount of mercury can be regulated with high accuracy. Claim 5
According to the present invention, it is possible to provide a lighting device, a lighting device, a backlight, and a liquid crystal display device, which make the most of the advantages of the cold cathode discharge lamp.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, FIG. 1 (A) is a diagram showing a configuration of a cold cathode discharge lamp lighting device provided with a cold cathode fluorescent lamp and a high frequency lighting circuit device, and FIG. ) A sectional view taken along the line BB in the figure.

2A and 2B show a structure of a cold cathode of the embodiment, FIG. 2A is a sectional view of the cold cathode, and FIG. 2B is a side view.

FIG. 3 is an exploded perspective view of a liquid crystal display device using the cold cathode discharge lamp device.

FIG. 4 is a cross-sectional view of the liquid crystal display device of the same embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cold cathode fluorescent lamp 2 ... High frequency lighting circuit device 10 ... Bulb 11 ... Phosphor layer 12, 12 ... Cold cathode 13 ... Electrode shaft 14 ... Electrode sleeve 14a ... Flat end 15 ... Amalgam and getter filling 16 ... Sealing Wiring 17 ... External lead wire 30 ... Backlight 31 ... Light guide plate 32 ... Reflector 33 ... Reflective surface 35 ... Reflector 36 ... Light diffuser 40 ... Liquid crystal display panel

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location // H05B 41/24 H05B 41/24 A

Claims (8)

[Claims] 1. A valve in which an ionizing medium is enclosed; an electrode shaft and an electrode sleeve which are provided at an end portion of the valve and have an electrode shaft, and the end portion of the electrode sleeve is crushed so that the electrode shaft has an electrode shaft. And a cold cathode in which the electrode sleeve and the electrode shaft are joined by being pressed against each other; the inner diameter of the bulb is Dmm, and the flat width of the flattened electrode sleeve is wmm. In this case, the cold cathode discharge lamp is characterized in that Dw ≧ 0.2 mm. 2. The cooling according to claim 1, wherein when the inner diameter of the electrode sleeve is d ₁ mm and the outer diameter of the electrode shaft is d ₂ mm, d ₁ −d ₂ ≦ 0.3 mm. Cathode discharge lamp. 3. The cold cathode discharge lamp according to claim 1, wherein the inner diameter D of the bulb is 3.0 mm or less. 4. The cold cathode discharge lamp according to claim 1, wherein at least an amalgam is held on the electrode sleeve. 5. A cold cathode discharge lamp comprising: the cold cathode discharge lamp according to any one of claims 1 to 4; and a lighting circuit for lighting the cold cathode discharge lamp. Lighting device. 6. A lighting device comprising: the cold cathode discharge lamp according to claim 1; and a lighting fixture to which the cold cathode discharge lamp is attached. 7. The cold cathode discharge lamp according to any one of claims 1 to 4, a reflector for reflecting light emitted from the cold cathode discharge lamp, and light reflected by the reflector. And a diffusing and transmitting means for diffusing and transmitting the light. 8. A liquid crystal display device, comprising: the backlight according to claim 7; and a liquid crystal display plate illuminated by the backlight.