JP3153825B2 - Display fluorescent lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a large-sized image display device,
The present invention relates to a fluorescent lamp for display which is suitable as a light emitting element used in a color image display device such as an electric bulletin board.

[0002]

2. Description of the Related Art Conventionally, as a display fluorescent lamp used in a display device such as a large-sized image display device, for example, a fluorescent lamp having a structure such as a discharge lamp disclosed in Japanese Utility Model Laid-Open No. 61-127562 is known. ing. These are provided with a pair of filament hot cathodes and anodes close to each other in a discharge tube, sealed with mercury and a rare gas inside, and discharged by the voltage applied between the preheated hot cathode and the anodes, mercury atoms Is excited to generate ultraviolet light, and is converted into visible light by a phosphor applied to the inner surface of the discharge tube to obtain a desired emission color.

[0003] Since these discharge lamps use negative glow light emission due to discharge, they have poor luminous efficiency. Further, in addition to the power required for discharge light emission, power for preheating the filament hot cathode is required. There is a problem that a large amount of heat is generated and the efficiency of the light emitting element as a whole is not good when used in an image display device. In addition, since the filament hot cathode cannot be made very small, the size of the light emitting element itself cannot be reduced, and there is also a problem that a high-definition image display device cannot be configured.

In order to reduce the size of the light emitting element itself, it is conceivable to use a cold cathode as the hot cathode of the filament. However, since the cold cathode cannot provide a large lamp current, a light emitting element with high brightness can be obtained. In addition, an appropriate distance between electrodes for generating a negative glow is required, and there is a limit in reducing the size of the light emitting element itself.

[0005] Further, since the display fluorescent lamp as described above has a low luminous efficiency, when a large number of display devices are used to constitute a display device, the problem of heat generation is serious, and a large-scale cooling device must be provided.

[0006] As means for solving the above-mentioned problems caused by providing a pair of electrodes inside the discharge tube, there is a method of using an internal electrode provided inside the discharge tube and an external electrode provided outside the discharge tube. There is a discharge lamp configured to discharge and emit light between them.

FIG. 8 is a longitudinal sectional view showing a conventional discharge lamp disclosed in, for example, Japanese Patent Publication No. 3-30259. In FIG. 8, reference numeral 1 denotes a conventional discharge lamp, and 2 denotes a rare gas such as internal xenon gas. Gas is several Torr to several hundred To
rr-enclosed glass bulb, 3 is an internal electrode provided substantially over the entire length of the glass bulb 2, 4 is an external electrode formed of a transparent conductive thin film and provided on the outer periphery of the glass bulb 2 facing the internal electrode 3, and 5 is an external electrode. This is a lead wire for connecting the electrode 4 to a power supply.

[0008] Between the internal electrode 3 and the external electrode 4, 200 to 2
When an AC voltage of about 000 V is applied, discharge occurs through a glass bulb 2 made of a dielectric material,
Almost all regions emit light with uniform luminance. In particular, when neon is used as the rare gas to be sealed, the glass bulb 2 emits orange light, and when krypton or xenon is used, it emits blue light. On the other hand, a desired luminescent color can be obtained by applying a fluorescent substance to the inner wall of the glass bulb 2.

The discharge lamp having the above-described structure is a glass bulb 2
Since the distance between the internal electrode 3 and the external electrode 4 is short even if the length is long, almost the entire area of the glass bulb 2 can be illuminated with a uniform luminance at a low voltage. A discharge lamp can be obtained and can be used as a display means for emitting letters, numbers, symbols, etc. by combining a single or a plurality of discharge lamps.

[0010]

Since the discharge lamp having the above-mentioned structure has a structure in which only one rod-shaped internal electrode 3 is contained in the glass bulb 2, a plurality of electrodes are contained in the glass bulb. It can be smaller than a discharge lamp having a structure. However, a phosphor layer is formed inside the glass bulb 2 and is not suitable for use as a light emitting element of a color display device such as a large-sized image display device or an electric signboard.

That is, since light is extracted from almost the entire area of the surface of the glass bulb, if the discharge lamps are laid sideways, the area of the pixels cannot be reduced, and light in directions other than the display surface cannot be reduced. It is wasted without being used.

[0012] When the discharge lamps are arranged upright,
Although the pixel area is almost the same as the cross-sectional area of the tube and can be arranged with high density, most of the light comes out from the side of the glass bulb that is not related to the display surface, so high brightness cannot be taken out with a small area and high brightness However, a high-definition image display device cannot be configured.

The present invention has been made to solve the above-mentioned problems of the prior art, and has a small light output area, a high luminance, a low heat generation and a high density display fluorescent lamp. The purpose is to obtain.

[0014]

For this reason, a fluorescent lamp for display according to the present invention comprises a cylindrical container made of a dielectric filled with a rare gas and a light-transmitting member formed on one end face of the container. A light output portion having, an internal electrode inserted into the container from the other end face portion of the container, a phosphor layer formed on an inner surface other than the light output portion of the container, and a light emitting portion other than the light output portion of the container. An object of the present invention is to achieve the above object by a configuration including an external electrode provided on an outer surface.

Also, a cylindrical container made of a dielectric material filled with a rare gas, a light-transmitting portion formed at one end of the container, and a light-transmitting portion formed at one end of the container. An internal electrode inserted therein, a plurality of phosphor layers having different emission colors formed on an inner surface other than the light output portion of the container, and the plurality of phosphor layers provided on an outer surface other than the light output portion of the container. A plurality of external electrodes are provided so as to oppose each other, and a voltage is applied between the plurality of external electrodes and the internal electrodes to achieve the above object. Things.

In each of the above structures, the surface of the external electrode on the container side is a substantially mirror-like surface for reflecting light, and the light for reflecting light from inside the container is provided between the phosphor layer and the inner wall surface of the container. It is an object of the present invention to achieve the above-described object by a configuration including a reflective film.

[0017]

The display fluorescent lamp according to the present invention discharges between the external electrode and the internal electrode through the dielectric cylindrical container with the above-described configuration. Such discharge forms a rare gas excimer near the inner wall of the container.
Ultraviolet rays emitted from the excimer do not cause self-absorption unlike the atomic resonance ultraviolet rays, and most of them reach the phosphor layer and are converted into visible light. This visible light is repeatedly reflected by the phosphor layer formed on the inner surface of the container, and is radiated from the light-transmitting light output portion in a concentrated manner.

Further, a structure is provided which includes a plurality of phosphor layers having different emission colors and a plurality of external electrodes facing the plurality of phosphor layers. When a voltage is applied to the device, the discharge occurs only in the portion where the voltage is applied, and a specific color and light emission are performed with high efficiency as described above, and the light is intensively irradiated from the light output portion.

Further, in the configuration in which the container-side surface of the external electrode is a substantially mirror-like surface that reflects light, the light that passes through the phosphor layer and leaks to the outside is prevented from being leaked to the outside by the container of the substantially mirror-shaped external electrode. The light is reflected from the side surface into the container, and is radiated from the light output portion in a concentrated manner.

Further, in a configuration in which a light reflecting film for reflecting light from inside the container is provided between the phosphor layer and the inner wall surface of the container, light passing through the phosphor layer is reflected by the light reflecting film on the inner wall side of the container. The light is reflected into the container and is radiated from the light output unit.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a display fluorescent lamp according to the present invention will be described with reference to embodiments.

(First Embodiment) FIG. 1 is a perspective view, partly in section, of a first embodiment, and FIG. 2 is a longitudinal sectional view of the first embodiment. is there.

Reference numeral 1 denotes a display fluorescent lamp according to the present invention;
Is a container constituting the display fluorescent lamp 1 and has a diameter of 3 m.
It is a straight cylindrical glass bulb with a length of 10 mm. From the lower end surface of the glass bulb 2, the internal electrode 3 is
The external electrode 4 is provided on the outer peripheral surface of the glass bulb 2, and the internal electrode 3 and the external electrode 4 are connected to a power source 6 by lead wires 5 a and 5 b.

A phosphor layer 7 is formed on almost the entire inner wall of the glass bulb 2 except for the upper end face. The upper end face of the glass bulb 2 has a light transmitting property and serves as a light output section 8. Xenon, which is a rare gas, is 200 To
rr enclosed.

The operation of the display fluorescent lamp (hereinafter, referred to as a lamp) 1 having the above configuration will be described. When a voltage is applied between the internal electrode 3 and the external electrode 4 from the power supply 6, a voltage is applied to the rare gas / xenon in the lamp via glass, which is a dielectric, to cause a discharge. The ultraviolet light generated at that time excites the phosphor layer 7 and is converted into a specific visible light determined by the phosphor.

Since the phosphor itself is white, the visible light generated from the phosphor is almost totally reflected by the phosphor layer 7 formed on the inner wall of the glass bulb 2 and returns to the inside of the glass bulb 2. Since this visible light is intensively applied to the outside of the glass bulb 2 from the light output section 8 having only a light transmitting property, a high-luminance light emitting element can be obtained.

Hereinafter, the principle of light emission will be described in detail. Because discharge is performed through glass that is a dielectric,
The current is limited by the dielectric, and the form of glow discharge to arc discharge does not develop. Further, the discharge does not concentrate on a specific place, and the discharge is generated from the entire inner surface of the glass bulb facing the external electrode. The current flows only immediately after the polarity of the applied voltage is reversed, otherwise the current stops due to the accumulation of charge on the inner surface of the glass bulb. Therefore, a pulsed current flows through the lamp.

When the internal discharge state of a lamp having no phosphor layer formed on the inner surface of the glass bulb is observed in detail, the entire inner surface of the lamp facing the external electrode is covered with substantially uniform blue-violet light. It can be seen that many thin string-like discharges connecting the internal electrode and the external electrode are generated. In such a discharge, the electrode drop voltage near the inner wall of the glass bulb where the external electrode is provided is large, and the current does not concentrate, so that the current density near the external electrode does not increase.

When a rare gas is sealed in a glass bulb, first, a rare gas atom is excited to a resonance level by collision with an electron accelerated by a strong electric field at the electrode falling part. Due to the high pressure of the rare gas, the excited atoms at the resonance level collide with other rare gas atoms at the ground level to form a diatomic molecule excimer. The excimer emits ultraviolet light and returns to two ground level rare gas atoms. Most of the ultraviolet light emitted by the excimer does not undergo self-absorption unlike the atomic resonance ultraviolet light, and most of the ultraviolet light reaches the inner wall of the glass bulb and is converted into visible light by the phosphor.
That is, in the case of excimer light emission, brighter light is obtained with high efficiency.

When xenon is used as a rare gas, a glow discharge lamp having electrodes therein has 14
While there is much 7 nm xenon resonant ultraviolet light, this fluorescent lamp for display mainly emits 172 nm excimer radiation. Further, when the wavelength of the ultraviolet light is long, the luminous efficiency of the phosphor is good and the deterioration is suppressed, so that it is advantageous in that a fluorescent lamp for display with high efficiency, high luminance and long life can be obtained.

FIG. 3 shows a change in the vacuum ultraviolet spectral distribution when the xenon sealing pressure is changed.
FIG. 3 does not show the wavelength sensitivity of the vacuum ultraviolet spectrometer. Since vacuum ultraviolet rays do not transmit through glass,
Instead of a glass bulb, a container of single crystal alumina (sapphire) transparent to vacuum ultraviolet rays was used. Of course, no phosphor layer is formed on the inner wall.

As shown in FIG. 3, the higher the sealing pressure, the smaller the 147 nm which is the atomic resonance ultraviolet ray.
Conversely, it can be seen that 172 nm of the ultraviolet light emitted by the excimer becomes dominant.

FIG. 4 shows the xenon sealing pressure and the lamp efficiency in the glass bulb 2 having the phosphor layer 7 formed on the inner wall. The lamp efficiency is obtained from a value obtained by dividing the luminance by the electric power.

It can be seen from FIG. 4 that the efficiency drops sharply as the sealing pressure decreases. This is because the emission of this lamp is due to ultraviolet rays generated by excimer, and the generation of excimer is due to collision between rare gas atoms.Therefore, if the sealing pressure is low, the probability of collision decreases and the probability of excimer formation Is considered to be low, and it is well understood that the result is also consistent with the result shown in FIG.

Excimer emitted ultraviolet light becomes remarkable at 30 Torr or more. At a pressure lower than 30 Torr, the discharge spreads like a glow discharge, and near-infrared radiation, which is an atomic spectrum of a rare gas, becomes strong. In terms of efficient generation of excimer and utilization of its emission, the sealing pressure is 30
Torr or more is desirable.

As described above, since the lamp 1 of this embodiment utilizes ultraviolet light generated by the excimer of a rare gas, the same amount of light can be obtained as compared with a normal fluorescent lamp utilizing excitation and emission of atoms in which self-absorption occurs. Is very small and the structure is suitable for taking out the generated light from the light output unit 8 having a small area, so that high brightness can be obtained with small power.

For example, a large-sized image display device used outdoors requires an average luminance of the display surface of about 5000 cd / m ^{2. In} this case, the aperture ratio of the general display surface is 40 to 50%.
Therefore, in the case of the RGB pixel array,
About 0000 cd / m ² is required. In general, such an outdoor large-sized image display device often has a pixel pitch of 10 mm or more, but the display fluorescent lamp of the present invention uses, for example, a glass bulb 2 having an outer diameter of 8 mm and a length of 12 mm.
Assuming that the sealing pressure of xenon is 200 Torr, about 0.1 W is sufficient, although it depends on the lighting conditions.

Compared to the high efficiency of the lamp of the above embodiment, about 1 W is required for the conventional fluorescent lamp in which a pair of filament hot cathode and anode are provided in the glass bulb. Further, even a fluorescent lamp having a structure in which one common hot cathode and a plurality of anodes, which are currently the mainstream, is provided, about 0.3 W is required. The efficiency of these conventional fluorescent lamps is low because the distance between the cathode and the anode cannot be made large, so that a positive column having the highest luminous efficiency is hardly formed.

On the other hand, the efficiency of the fluorescent lamp for display according to the present invention does not depend on the size of the lamp because the fluorescent lamp for display according to the present invention utilizes the ultraviolet light generated by the excimer. Further, since the above two conventional fluorescent lamps use a filament hot cathode, electric power for preheating is required. Heat loss is a major problem in these conventional fluorescent lamps because heat is lost during the input power except for conversion into light.

As described above, the fluorescent lamp for display according to the present invention has high brightness, small size, low heat generation, and can be arranged at high density. It is most suitable as an element. Further, it is not necessary to use a large-scale cooling device, the structure of the light-emitting display element is extremely simple, and the manufacture is easy.

(Second Embodiment) FIG. 5 is a longitudinal sectional view of the second embodiment, and FIG. 6 is a transverse sectional view of the second embodiment. Description is omitted.

The lamp 1 of the second embodiment has a glass bulb 2
A plurality of phosphor layers of different emission colors are provided on the inner wall so as to divide the inner wall. That is,
The phosphor layers 7R, 7G, and 7B are phosphors that emit red, green, and blue light, respectively, and are provided on the inner wall surface of the glass bulb 2 so as to have substantially the same area. Further, phosphors 7R and 7R having different emission colors are provided on the outer wall surface side of the glass bulb 2.
External electrodes 4R, 4G, and 4B are provided to face G and 7B. Each external electrode 4G, 4R, 4B is
It is connected to a power supply 6 via switching elements 9R, 9G, 9B so that a voltage can be selectively applied to the internal electrode 3.

In the lamp 1 of the second embodiment having the above-described structure, when the external electrodes 4R, 4G, and 4B are selected and a voltage is applied, a discharge occurs between the selected external electrode and the internal electrode 3, and the non-selected electrode is formed. The discharge does not spread to the portion, and excimer is generated only on the selected external electrode surface. The ultraviolet light generated by the excimer excites the selected phosphor layer and emits light in the color of the phosphor. However, since the discharge does not spread, the non-selected phosphor layer is hardly excited. The visible light converted by the selected phosphor does not excite the phosphor and the glass bulb 2
The light is repeatedly reflected inside, and is radiated from the light output unit 8 in a concentrated manner.

By adjusting the power applied to the external electrode facing each phosphor layer by a method such as on / off time control, the amount of red, green and blue light can be adjusted. Thus, a mixed fluorescent light is emitted to obtain a display fluorescent lamp that can display full color with one light emitting element.

In this embodiment, the areas of the phosphor layers 7R, 7G, 7B having different emission colors are formed to be substantially the same.
An arbitrary ratio may be provided according to the luminous efficiency of the phosphor.

(Third Embodiment) In the first and second embodiments, if the inner surface of the external electrode is made of a metal film such as aluminum or silver, or a mirror-like surface such as a metal tape, the lamp can be used. Since the light leaking from the side surface to the outside is completely reflected inside the lamp, the brightness of the light output unit 4 can be further increased. A similar effect can be obtained by a structure in which a non-conductive mirror-like film is provided on the inner surface of a non-mirror-like external electrode.

(Fourth Embodiment) FIG. 7 is a cross-sectional view of the fourth embodiment, in which a light reflecting film 10 is formed between a glass bulb 2 and a phosphor layer 7. is there.

If the light reflecting film 10 has, for example, a property of reflecting visible light, visible light which passes through the phosphor layer 7 on the inner wall of the glass bulb 2 and slightly leaks to the outside is also introduced into the glass bulb 2. Reflection can further improve the efficiency.

If the light reflecting film 10 has a characteristic of reflecting ultraviolet light, it is not converted into visible light by the phosphor layer 7;
The ultraviolet rays reaching the inner wall of the glass bulb are reflected back into the glass bulb 2. Since this display fluorescent lamp uses the ultraviolet light of excimer in particular, the ultraviolet light reflected in the glass bulb 2 reaches the phosphor layer 7 without self-absorption again to increase the luminance, so that the excitation of atoms is performed. This is particularly effective as compared with a fluorescent lamp using ultraviolet light by light emission.

A film provided with both a visible light reflecting film and an ultraviolet light reflecting film can obtain both of the above characteristics.

(Fifth Embodiment) In each of the above embodiments, the lower end face of the glass bulb 2 is not particularly described. However, the lower end face may be made of a material such as white, or the phosphor layer may be provided up to the lower end face. The light generated inside the lamp can be almost completely extracted from the light output unit 8 only.

Sixth Embodiment In each of the above embodiments, a case was described in which xenon was sealed in the lamp. However, another rare gas such as krypton, argon, neon, helium, or a mixture of two or more rare gases was used. May be sealed.

(Seventh Embodiment) In each of the above embodiments,
Although the glass bulb 2 for enclosing the rare gas is cylindrical, any shape may be used as long as it can enclose the rare gas, for example, a prism or the like, and the end face may be flat or curved. The material is not limited to glass but may be a dielectric, and the size is not limited.

(Eighth Embodiment) In each of the above embodiments, the external electrode is a sheet-like electrode. However, a net-like electrode or an electrode in which a plurality of linear electrodes are arranged in parallel may be used. The internal electrodes are also rod-shaped, but any shape may be used as long as the electrodes are conductive. Metal is desirable as the material. Further, an electron emitting substance may be applied to the internal electrode.

[0055]

As described above, according to the present invention, a discharge is generated between an external electrode and an internal electrode via a cylindrical container which is a dielectric, and excimer of a rare gas is formed near the inner wall of the container. Is done. The ultraviolet light emitted from this excimer does not cause self-absorption unlike the atomic resonance ultraviolet light,
Most of them reach the phosphor layer and are converted into visible light with high efficiency. This visible light is repeatedly reflected by the phosphor layer formed on the inner surface of the container, and concentrated from the light output portion having translucency.
Irradiation results in high efficiency and high brightness, and low heat generation.

Moreover, the area of the light output section can be made substantially equal to the cross-sectional area of the container, and a fluorescent lamp for display suitable as a light emitting display element of an image display device can be obtained. An image display device with high luminance and high definition can be configured.

Further, a plurality of phosphor layers having different emission colors and a plurality of external electrodes facing the plurality of phosphor layers are provided, and a voltage is applied between the plurality of external electrodes and the internal electrodes. When the voltage is applied, only the portion where the voltage is applied discharges and emits a specific color and light with high efficiency and is radiated from the light output portion in a concentrated manner as described above. A multi-color light can be emitted by a lamp, and a display fluorescent lamp suitable for a light-emitting display element of a full-color image display device can be obtained. A high-density arrangement and high-luminance, high-definition full-color image display device can be obtained. be able to.

Further, in the configuration in which the container-side surface of the external electrode is formed as a substantially mirror-like surface that reflects light, light that passes through the phosphor layer and leaks to the outside is prevented from leaking to the outside of the substantially mirror-shaped container of the external electrode. The light is reflected from the side surface into the container, and can be irradiated with higher efficiency and higher brightness from the light output unit. Further, in a configuration including a light reflecting film that reflects light from inside the container between the phosphor layer and the inner wall surface of the container, light passing through the phosphor layer is transmitted into the container by the light reflecting film on the inner wall side of the container. from the reflected light output section can be illuminated with higher efficiency and high luminance.

[Brief description of the drawings]

FIG. 1 is a partially sectional perspective view showing a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the first embodiment.

FIG. 3 is a diagram showing a change in a vacuum ultraviolet spectral distribution depending on a sealing pressure of xenon.

FIG. 4 is a diagram showing a relationship between a rare gas charging pressure and lamp efficiency.

FIG. 5 is a longitudinal sectional view showing a second embodiment of the present invention.

FIG. 6 is a cross-sectional view of the second embodiment.

FIG. 7 is a sectional view showing a fourth example of the present invention.

FIG. 8 is a longitudinal sectional view showing a conventional fluorescent lamp.

[Description of References] 1 Fluorescent lamp for display 2 Container (glass bulb) 4 External electrode 7 Phosphor layer 8 Light output part In the drawings, the same reference numerals indicate the same or corresponding parts.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichiro Hoshizaki 2-14-40, Ofuna, Kamakura City, Kanagawa Prefecture Mitsubishi Electric Corporation Living System Laboratory (56) References JP-A-2-309552 (JP, A) JP-A-63-37556 (JP, A) JP-A-61-63760 (JP, U) JP-A-3-50752 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 65/00 G09F 9/313 G09F 13/26

Claims (4)

(57) [Claims] 1. A cylindrical container which is a dielectric filled with a rare gas, a light-transmitting portion formed on one end surface of the container, and a light output portion having a light-transmitting property. An internal electrode inserted therein, a phosphor layer formed on an inner surface of the container other than the light output portion, and an external electrode provided on an outer surface of the container other than the light output portion. Fluorescent lamp. 2. A container formed of a dielectric material filled with a rare gas, a light-transmitting portion formed on one end of the container, and a light-transmitting portion formed on one end of the container. Internal electrodes inserted therein, and a plurality of phosphor layers having different emission colors formed on the inner surface other than the light output portion of the container,
A plurality of external electrodes facing the plurality of phosphor layers provided on the outer surface other than the light output portion of the container, wherein a voltage is applied between the plurality of external electrodes and the internal electrodes by selecting the plurality of external electrodes. A display fluorescent lamp, characterized in that: 3. A container-side surface of the external electrode is a substantially mirror-like surface that reflects light.
Fluorescent lamp for display as described. 4. The fluorescent lamp for display according to claim 1, further comprising a light reflecting film for reflecting light from inside the container between the phosphor layer and the inner wall surface of the container.