JPH09265945A - Fluorescent lamp, back light device and manufacture of fluorescent lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce drive electric power, and enhance illumination effect. SOLUTION: On the inner face of a glass bulb 2 first layer phosphor layer 4 is formed leaving an opening portion 3 which becomes one part area in a peripheral direction, and second layer phosphor layer 5 having higher transmittance than the transmittance of the first phosphor layer 4 is formed on the opening portion 3 area and the inner peripheral face of the first layer phosphor layer 4. Accordingly, the second layer phosphor layer 5 penetrates one part of light but reflects the remaining light toward the opening portion 3, and the first layer phosphor layer 4 reflects the most light penetrated the second layer phosphor layer 5 toward the opening portion 3. By collecting the light generated in the glass bulb 2 and radiating the light from the opening portion 3, electric power is reduced and illumination effect is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent lamp, a backlight device and a method for manufacturing a fluorescent lamp.

[0002]

2. Description of the Related Art Conventionally, there is a fluorescent lamp in which a single phosphor layer is coated on the inner peripheral surface of a glass tube. Such a fluorescent lamp has a substantially uniform luminous flux distribution in the radial direction from the center of the glass tube. However, various types of fluorescent lamps have been proposed because the utilization efficiency of light is poor when illuminating a specific direction.

For example, as disclosed in Japanese Patent Publication No. 63-37458, it is disclosed that two phosphor layers are formed on the inner peripheral surface of a glass tube. In this case, in order to form an opening functioning as an aperture on the inner peripheral surface of the glass tube, the fluorescent layer of the second layer is different from the conventional fluorescent lamp which regulates the application area of the fluorescent layer of the first layer. A fluorescent lamp has been proposed that regulates the application area of the.

[0004]

As the performance of a fluorescent lamp, it is one of the important issues to improve the light utilization efficiency. Further, it is very difficult to regulate the application area of the phosphor layer on the inner peripheral surface of the glass tube to form the opening. In particular, in the case of a glass tube having an inner diameter of 4 mm or less, it is not possible to mask and apply the phosphor layer. After applying the phosphor layer on the entire surface, the phosphor layer in the area corresponding to the opening is scratched and removed. Laborious work to do. Such work may cause a problem that the inner surface of the opening is damaged.

An object of the present invention is to provide a method for manufacturing a fluorescent lamp, a backlight, which can improve the light utilization efficiency, and a fluorescent lamp in which a phosphor layer and an opening can be easily formed.

[0006]

A fluorescent lamp according to the present invention is a linear glass bulb, which is formed on the inner surface of the glass bulb leaving an opening which is a partial region in the circumferential direction. A first phosphor layer; formed on the region of the opening of the glass bulb and the inner peripheral surface of the first phosphor layer, and having a higher transmittance than the first phosphor layer; A second phosphor layer; electrodes disposed at both ends of the glass bulb; and a discharge medium sealed in the glass bulb.

Various glass materials such as soda lime glass, borosilicate glass and quartz glass can be applied to the glass bulb. If it is translucent, it may be replaced with a material such as ceramics. The transmittance τ is τ = F, where Fi is an incident light flux incident on the phosphor layer and Ft is a transmitted light flux.
It is defined by t / Fi. This transmittance is the thickness of the phosphor layer,
It is possible to set a desired value by adjusting the particle size, shape, type, etc. of the phosphor particles. Mercury, xenon, etc. are used as the discharge medium, and argon, neon,
It may be a mixture of noble gases such as krypton.

Ultraviolet rays are radiated from the discharge medium into the glass bulb due to the discharge between the electrodes.
The layer and the second phosphor layer are excited to be converted into visible light.
The second phosphor layer transmits a relatively large amount of light. The first phosphor layer reflects most of the light transmitted through the second phosphor layer toward the opening.

The invention according to claim 2 is the fluorescent lamp according to claim 1, wherein the glass bulb has an inner diameter of 4 mm or less, and the electrode is a cold cathode.

[0010] The third aspect of the present invention is the first or second aspect.
In the fluorescent lamp according to any one of items 1 to 5, the transmittance of the first phosphor layer is set to 30% or less.

The invention according to a fourth aspect is the first to the third aspects.
In the fluorescent lamp according to any one of 1 to 3, the opening angle of the opening is set to 30 ° to 180 °.

A backlight device according to a fifth aspect of the present invention includes the fluorescent lamp according to any one of the first to fourth aspects, on a side surface of a light guide unit provided along a back surface of the liquid crystal display element. . Therefore, ultraviolet rays are radiated from the discharge medium into the glass bulb by the discharge between the electrodes, and the ultraviolet rays excite the first and second phosphor layers to be converted into visible light. The second phosphor layer transmits a relatively large amount of light. The first phosphor layer reflects most of the light transmitted through the second phosphor layer toward the opening. The light from the fluorescent lamp is applied to the light guide unit.

According to a sixth aspect of the present invention, there is provided a method for manufacturing a fluorescent lamp, wherein a glass bulb having an inner diameter of 4 mm or less is supported by being inclined at a predetermined angle in the vertical direction from one end to the other end, and a liquid fluorescent agent having a low transmittance is provided. By pouring from the upper end to the lower end of the glass bulb in a state where it does not reach the opening which is a part of the circumferential direction of the inner circumferential surface of the glass bulb, thereby opening the inner circumferential surface of the glass bulb. And a first-layer phosphor layer forming step of forming a first-layer phosphor layer that covers the region other than the opening, and the inside of the region of the opening of the glass bulb and the first-layer phosphor layer. A second layer phosphor layer forming step of forming a second layer phosphor layer having a transmittance higher than that of the first phosphor layer on the peripheral surface; and a discharge medium inside the glass bulb. Encapsulation process: Encapsulating electrodes on both ends of the glass bulb An electrode sealing step that; the more. Therefore, in the first phosphor layer forming step, when the tilt angle of the glass bulb, the specific gravity of the liquid phosphor, the pouring speed of the phosphor, etc. are controlled, the phosphor tends to spread in the circumferential direction of the glass bulb. Is maintained in an optimum state by the surface tension and flows in the glass bulb. As a result, when the fluorescent agent reaches from the upper end to the lower end of the glass bulb, the first phosphor layer is formed, and at the same time, the opening is formed in the area where the fluorescent agent does not reach.

In this case, the specific gravity of the liquid fluorescent agent forming the first fluorescent layer is preferably 1.60 or less, and the pouring speed into the glass bulb is preferably 0.01 cc / sec.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a fluorescent lamp of the present invention will be described with reference to FIG. FIG. 1 is a vertical sectional side view of a fluorescent lamp. In FIG. 1, the glass bulb 2 of the fluorescent lamp 1 has an outer diameter of 2.6 mm and an inner diameter of 2.0 in this example.
mm and the length is set to 230 mm. A first phosphor layer 4 is formed on the inner surface of the glass bulb 2, leaving an opening 3 that is a partial region in the circumferential direction.
A second-layer phosphor layer 5 is formed on the above region and the inner peripheral surface of the first-layer phosphor layer 4. The opening angle α of the opening 3 is 1
It is set at 20 °. The first phosphor layer 4 has a transmittance of 20%, and the second phosphor layer 5 has a transmittance of 40%. Rare earth phosphors having three wavelengths are used. A discharge medium made of argon gas and mercury vapor is sealed inside the glass bulb 2 and electrodes (not shown) made of cold cathodes are provided at both ends in the longitudinal direction. The electrodes may be hot cathodes made of filaments.

Next, the operation will be described. When a certain voltage is applied to the electrodes, the glass bulb 2 is discharged due to the discharge between the electrodes.
Ultraviolet rays are radiated from the discharge medium, and the ultraviolet rays excite the first and second phosphor layers 4 and 5 to be converted into visible light. The second phosphor layer 5 transmits a relatively large amount of light, but the first phosphor layer 4 reflects most of the light transmitted through the second phosphor layer 5 toward the opening 3. To do. In this way, since the light generated in the glass bulb 2 can be condensed and emitted from the opening 3, brighter illumination can be performed with a small driving power.

Next, the backlight device of the present invention will be described with reference to FIG. FIG. 2 is a vertical sectional side view of the backlight device. Since the fluorescent lamp 1 is similar to that of the previous embodiment, the same reference numerals are used and the description thereof is omitted. As shown in FIG. 2, the backlight device 6 includes a light guide unit 7 and a plurality of fluorescent lamps 1 arranged on both sides of the light guide unit 7. The light guide unit 7 includes a reflection sheet 8, a light guide plate 9, and a light diffusion sheet 10.
And prism sheets 11 and 12 are laminated. The base frame 13 is arranged on the side of the reflection sheet 8 of the light guide unit 7, and the prism sheet 12 is provided.
A frame-shaped front frame 14 is arranged on the side. The front frame 14 is arranged so as to face an entrance surface of a transmissive liquid crystal display element (not shown). Then, holders 15 are fitted to both ends of the fluorescent lamp 1, these holders 15 are fitted to both ends of a U-shaped curved reflection sheet 16, and both sides of the light guide unit 7 are fitted to these reflection sheets 16. Then, in this state, the light guide unit 7, the reflection sheet 16, the base frame 13, and the front frame 14 are fastened in a laminated state to assemble the backlight device 6. In this case, the opening 3 of the fluorescent lamp 1 is directed to the side surface of the light guide plate 9.

Next, the operation will be described. When a certain voltage is applied to the electrodes, the glass bulb 2 is discharged due to the discharge between the electrodes.
Ultraviolet rays are radiated from the discharge medium, and the ultraviolet rays excite the first and second phosphor layers 4 and 5 to be converted into visible light. The second phosphor layer 5 transmits a relatively large amount of light, but the first phosphor layer 4 reflects most of the light transmitted through the second phosphor layer 5 toward the opening 3. To do. The first-layer fluorescent body 4 transmits a part of light, and the transmitted light is reflected by the reflection sheet 16 to the opening 3.
The light emitted from the fluorescent lamp 1 in this way is incident from the side surface of the light guide plate 9, and the incident light is reflected by the reflection sheet 8, transmitted through the light guide plate 9, diffused by the light diffusion sheet 10, and formed into a prism. The emission direction is determined by the sheets 11 and 12, and the light is incident on the incident surface of the liquid crystal display element.

Here, the outer diameter of the glass bulb 2 of the fluorescent lamp 1 is 2.6 mm, the inner diameter is 2.0 mm, the opening angle α of the opening 3 is 120 °, and the transmittance of the first phosphor layer 4 is 20
%, The transmittance of the second phosphor layer 5 is 40%, the power applied to the electrode (cold cathode) is 2.4 W (5 mA), and the size of the light guide plate 9 is 10.4 inches (thickness 3 mm). The tube surface brightness of the fluorescent lamp 1 is 44000 cd / m on the opening 3 side.
² , the result was 21000 cd / m ² on the side opposite to the opening 3, and the plate surface luminance of the backlight device 6 was 2500 cd / m ² .

By the way, in comparison with the case where a conventional fluorescent lamp in which a single phosphor layer is formed on the entire inner peripheral surface of the glass bulb is used and other parameters are given the above-mentioned values,
Tube surface luminance of the fluorescent lamp 32000cd / m ^2, the plate surface luminance of the backlight device was 2000 cd / m ^2.

That is, according to the configuration of the present invention, the plate surface luminance of the backlight device 6 can be improved by about 25%. If the brightness is made equal, the power consumption can be reduced by about 25%.

Next, an embodiment of the method for manufacturing a fluorescent lamp according to the present invention will be described with reference to FIGS. FIG. 3 is a vertical sectional front view showing a state in the first phosphor layer forming step,
FIG. 4 is a vertical cross-sectional side view of the glass bulb in a state where a first phosphor layer forming step has been performed. The same parts as those in the previous embodiment are designated by the same reference numerals and the description thereof will be omitted. The fluorescent lamp 1 of the present invention is the first
The layer phosphor layer forming step, the second layer phosphor layer forming step, the encapsulating step, and the electrode forming step are performed.

In the first phosphor layer forming step, as shown in FIG. 3, the glass bulb 2 having an inner diameter of 4 mm or less (in the present embodiment, an outer diameter of 2.6 mm and an inner diameter of 2 mm) is connected from one end to another. It is supported by inclining vertically toward the end by a predetermined angle. Then, the liquid fluorescent material 18 with low transmittance stored in the container 17
From the upper end of the glass bulb 2 to the lower end thereof, which is a part of the inner peripheral surface of the glass bulb 2 in the circumferential direction.
(See FIG. 4), the opening 3 and the first phosphor layer 4 covering the area other than the opening 3 are formed on the inner peripheral surface of the glass bulb 2 by pouring in a state not reaching the opening.

In this example, the inclination angle of the glass bulb 2 is about 45 ° and the specific gravity of the phosphor slurry (fluorescent agent) 18 is 1.
6 or less, by pouring the phosphor slurry 18 in the container 17 using a pipe 19 having a thickness about one third of the inner diameter of the glass bulb 2, the pouring speed is 0.01 cc / se.
Specified in c. As a result, the phosphor slurry 18 flows in the glass bulb 2 while the action of expanding the glass bulb 2 in the circumferential direction of the glass bulb 2 is maintained in an optimum state by the surface tension.
Thus, when the phosphor slurry 18 reaches the lower end from the upper end of the glass bulb 2, the first phosphor layer 4 is formed, and at the same time, the opening 3 is formed in a region where the phosphor slurry 18 does not reach. Both sides of the opening 3 (edges of the boundary with the first phosphor layer 4) form a clean straight line.

In the second layer phosphor layer forming step, the second layer phosphor layer 5 is formed on the inner peripheral surface of the glass bulb 2. In this step, the region of the opening 3 of the glass bulb 2 and the first layer are formed. Since the second layer phosphor layer 5 is formed on the inner peripheral surface of the first layer phosphor layer 4, it is not necessary to define the area of the opening 3, and it can be easily formed by various methods including conventional methods. You can

The sealing process for sealing the discharge medium inside the glass bulb 2 and the electrode sealing process for sealing the electrodes on both ends of the glass bulb 2 are the same as those in the conventional method, and therefore their explanations are omitted.

The first phosphor layer forming step shown in FIG. 3 can also be used as a step of forming a reflective film in a reflective fluorescent lamp. In this case, in place of the phosphor slurry 18, titanium oxide or aluminum oxide is melted with a binder to be liquefied and poured into the glass bulb 2, so that titanium oxide is left on the inner surface of the glass bulb 2 with an opening left. It is possible to form a reflective film of aluminum oxide or the like.

In the previous embodiment, the fluorescent lamp 1 shown in FIG. 1 was used as the light source of the backlight device 6, but a modification of the light source will be described with reference to FIGS. 5 and 6. FIG. 5 is a vertical cross-sectional front view showing the double-tube type fluorescent lamp, and FIG. 6 is a vertical cross-sectional front view showing the state in which the outer leads connected to the electrodes are covered with an insulating material. The double-tube fluorescent lamp 20 shown in FIG. 5 is a glass in which a phosphor layer (not shown) is formed, argon gas or mercury is filled, and electrodes 22 to which outer leads 21 are connected are provided at both ends. Valve 23
And a glass bulb 24 that covers the outside of the glass bulb 23 by maintaining a vacuum inside or enclosing a buffer gas such as mercury.

The double-tube type fluorescent lamp 20 as described above is
When the both ends of the inner and outer glass bulbs 23 and 24 are sealed, dents and cracks may occur at both ends of the inner glass bulb 23. This is the inner glass bulb 23
The outer lead 21 is exposed between the outer glass bulb 24 and the inside of the outer glass bulb 24.

Therefore, in this example, as shown in FIG.
The outer lead 21 is covered with an insulating material 25 such as glass beads over a predetermined range from the electrode 22 side (a range reaching the sealing portion with the outer glass bulb 24), and then the glass bulbs 23, 24 are joined together. As shown in FIG. 5, the outer lead 21 can be prevented from being exposed inside the glass bulb 24 by sealing.

[0031]

According to the inventions of claims 1 to 4, the first phosphor layer is formed on the inner surface of the glass bulb, leaving an opening which is a partial region in the circumferential direction. A second phosphor layer having a transmittance higher than that of the first phosphor layer is formed in the area of the opening of the glass bulb and the inner peripheral surface of the first phosphor layer. Therefore, the phosphor layer of the second layer transmits a part of the light but reflects the remaining light toward the opening, and the phosphor layer of the first layer reflects the light transmitted through the phosphor layer of the second layer. Most of the light is reflected toward the opening. In this way, since the light generated in the glass bulb can be condensed and emitted from the opening, brighter illumination can be performed with a small driving power.

According to the invention of claim 5, the fluorescent lamp according to any one of claims 1 to 4 is provided on the side surface of the light guide unit provided along the back surface of the liquid crystal display element. The two-layer phosphor layer transmits a part of the light but reflects the remaining light toward the opening portion, and the first-layer phosphor layer absorbs most of the light transmitted through the second-layer phosphor layer. Reflect toward the opening. As described above, since the light generated in the glass bulb can be condensed and emitted from the opening, it is possible to provide a backlight device capable of performing brighter illumination with a small driving power.

According to the sixth aspect of the present invention, in the first phosphor layer forming step, the glass bulb having an inner diameter of 4 mm or less is supported by being inclined at a predetermined angle in the vertical direction from one end to the other end, and the transmittance of the glass bulb is reduced. By injecting a low liquid fluorescent agent from the upper end of the glass bulb toward the lower end in a state where it does not reach the opening which is a part of the circumferential direction of the inner peripheral surface of the glass bulb, the inside of the glass bulb Since the opening and the first phosphor layer covering the area other than the opening are formed on the peripheral surface, the inclination angle of the glass bulb, the specific gravity of the liquid fluorescent agent, the pouring speed of the fluorescent agent, etc. By controlling the temperature of the glass bulb, the action of the fluorescent agent trying to spread in the circumferential direction of the glass bulb is maintained in an optimal state by the surface tension and flows in the glass bulb. From the top The phosphor layer of the first layer is formed when it reaches the end, it is possible to form an aperture fluorescent agent to beyond the area at the same time. In addition, the boundary edge between both sides of the opening and the first phosphor layer can be made into a straight line.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of a fluorescent lamp of the present invention.

FIG. 2 is a vertical sectional side view showing an embodiment of a backlight device of the present invention.

FIG. 3 is a vertical sectional front view showing a state in a first phosphor layer forming step in the method for manufacturing a fluorescent lamp of the present invention.

FIG. 4 is a vertical cross-sectional side view of a glass bulb in a state after a first phosphor layer forming step.

FIG. 5 is a vertical sectional front view showing a double-tube fluorescent lamp as a modified example.

FIG. 6 is a vertical sectional front view showing a state in which an outer lead to which an electrode is connected is covered with an insulating material.

[Explanation of symbols]

 1: Fluorescent Lamp 2: Glass Bulb 3: Opening 4: First Layer Phosphor Layer 5: Second Layer Phosphor Layer 7: Light Guide Unit 18: Fluorescent Agent 20: Fluorescent Lamp 22: Electrodes 23, 24: Glass bulb

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01J 61/30 H01J 61/30 R

Claims (6)

[Claims] 1. A linear glass bulb; a first phosphor layer formed on the inner surface of the glass bulb, leaving an opening to be a partial region in the circumferential direction; A second phosphor having a higher transmittance than that of the first phosphor layer, the second phosphor formed on the region of the opening and the inner peripheral surface of the first phosphor layer.
A fluorescent lamp comprising: a phosphor layer of a layer; electrodes disposed at both ends of the glass bulb; and a discharge medium sealed in the glass bulb. 2. The fluorescent lamp according to claim 1, wherein the glass bulb has an inner diameter of 4 mm or less, and the electrode is a cold cathode. 3. The fluorescent lamp according to claim 1, wherein the first phosphor layer has a transmittance of 30% or less. 4. The fluorescent lamp according to claim 1, wherein the opening angle of the opening is set to 30 ° to 180 °. 5. A backlight device comprising the fluorescent lamp according to claim 1 on a side surface of a light guide unit provided along a back surface of a liquid crystal display element. 6. A glass bulb having an inner diameter of 4 mm or less is supported by tilting from one end to the other end in a vertical direction at a predetermined angle, and a liquid fluorescent agent having a low transmittance is directed from the upper end to the lower end of the glass bulb. The first layer that covers the opening and the area other than the opening on the inner peripheral surface of the glass bulb by pouring in a state where it does not reach the opening that is a partial area of the inner peripheral surface of the glass bulb in the circumferential direction. A first-layer phosphor layer forming step of forming a first phosphor layer and the inner peripheral surface of the first-layer phosphor layer having a transmittance of the first layer. A second layer phosphor layer forming step of forming a second phosphor layer having a higher transmittance than the phosphor layer; an encapsulating step of enclosing a discharge medium inside the glass bulb; both ends of the glass bulb An electrode sealing step of sealing the electrode; Fluorescent lamp manufacturing method.