JPH08287714A - Fluorescent lighting system - Google Patents

Abstract

PURPOSE: To improve luminescence efficiency of a fluorescent lighting system to be employed for a planar light source so called as a side light type. CONSTITUTION: Mercury and a rare gas such argon gas at low pressure are sealed in the interior of a glass tube 11 whose inside is kept air-tight and which has either a linear shape or at least one curved part and discharge electrodes are arranged in both end parts of the glass tube 11 to compose a discharge lamp 18. A reflecting plate 20 to reflect ultraviolet-rays is installed in the outside of the glass tube 11 and a phosphor body 12 to convert the ultraviolet-rays to visible light-rays is applied to the face to which the ultraviolet-rays 16 emitted from the glass tube 11 and reflected by the reflecting plate 20 are radiated. Since not like a case of a conventional fluorescent lamp, the light-rays reflected and turned back to the inside of the tube are not absorbed in the phosphor layer, the luminescence efficiency is heightened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a back lighting for signs and various display devices, and more particularly to a fluorescent lighting device used for a thin planar light source device such as a back lighting means of a liquid crystal display device.

[0002]

2. Description of the Related Art As means for realizing a thin planar light source,
Conventionally, a side light method (light guide plate method) is known. One example thereof will be described with reference to FIG. Reference numeral 1 denotes a transparent resin substrate having a substantially rectangular cross section made of a highly transparent material such as acrylic. The back surface 2 of the transparent resin substrate 1 is provided with a scattering pattern printed with white or milky white ink so that its density changes from one end side to the other end side. This coating method is disclosed in JP-A-63-62105.

A reflecting plate 3 is provided behind the transparent resin substrate 1, and a diffusing plate 5 is provided on the front surface 4 side (observation side). Furthermore, at least one or more end portions 6 of the transparent resin substrate 1 are provided with one or a plurality of cold cathode or hot cathode fluorescent tubes 7 so as to substantially contact the end portions 6,
The outer periphery thereof is covered with a reflective film 8 having an inner surface deposited with silver or the like. Both ends of the reflective film 8 are adhered to the front and back of the transparent resin substrate 1, respectively. A reflective material 9 such as a reflective tape is added to the surface of the end portion 6 of the transparent resin substrate 1 on which the fluorescent tube 7 is not placed.

As a light emitting source of the side light type planar light source device having the above structure, a fluorescent tube is generally used because of its good light emitting efficiency. As shown in FIG. 6, the fluorescent tube 7 has a glass tube 11 with electrodes 10 attached to both ends and kept airtight.
The structure is such that the phosphor 12 is applied to the inner surface of the. In the airtight space, after the internal air is exhausted, a rare gas such as argon of 0.2 to 0.7 kPa and a small amount of mercury are usually mixed. A part of this mercury is evaporated in the space inside the tube, and it becomes a mixed gas with the mixed rare gas.

When a discharge is started between the electrodes 10 at both ends of the glass tube 11, electric energy is converted into ultraviolet rays having a main wavelength of 254 mm and 185 mm in the discharge space inside the tube, and this ultraviolet radiation excites the fluorescent substance on the tube wall. Source and phosphor 12
Visible light converted by is emitted. The fluorescent tubes are roughly classified into a cold cathode tube that uses a glow discharge area and a hot cathode tube that uses an arc discharge area. 6 shows an example of the structure of the hot cathode tube, the cold cathode tube has the same basic structure as the hot cathode tube except that the electrode shape is slightly different. Both have been conventionally used as a light source of a light source.

FIG. 7 is a schematic cross-sectional view for explaining the behavior of light rays at the connecting portion between the fluorescent tube 7 and the end portion 6 of the transparent resin substrate 1 in the conventional structure. Fluorescent tube 7
Of the ultraviolet rays generated in the interior 13 of the inside, the ultraviolet rays 14 that reach the phosphor layer 12 on the resin substrate edge 6 side are converted into visible light 15, and most of them reach the resin substrate edge 6, and the planar light source device It becomes a light ray that acts on the surface emission of.

Of the ultraviolet rays generated in the inside 13 of the fluorescent tube 7, the ultraviolet rays 16 reaching the fluorescent layer 12 on the opposite side of the resin substrate end 6 are converted into visible rays 17, and most of the rays are again inside the tube. Returning to the phosphor layer 12 in the peripheral portion, most of the light is absorbed here, resulting in a large loss.

At present, the luminous efficiency of this portion is 5
It is said that it is about 0 to 60%, and various proposals have been made regarding methods for reducing the emitted light rays to the inside of the tube as much as possible by devising the shape of the reflective film 8. In the current situation where the outer diameter of 7 does not become sufficiently small,
No big improvement can be expected.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of this point, and an object of the present invention is to provide a fluorescent lighting device capable of guiding light into a transparent resin substrate more efficiently.

[0010]

As a means for solving the above-mentioned problems, the present invention is the invention as set forth in claim 1, wherein the inside is airtightly straight or at least 1.
A low-pressure mercury gas and a rare gas such as argon gas are enclosed in a glass tube having at least one bent portion, and discharge electrodes are arranged at both ends of the glass tube to form a discharge tube. Form a reflective layer that reflects ultraviolet rays to the outside,
The surface of the glass tube that is exposed to the reflected ultraviolet light is coated with a phosphor for converting the ultraviolet light into visible light.

According to the invention described in claim 2, in the invention described in claim 1, the glass tube is made of a material which transmits 60% or more of ultraviolet rays in a wavelength range of at least 150 to 300 nm. And

In the invention described in claim 3, in the invention described in claim 1, the material of the glass tube is
It is characterized by being quartz glass.

According to the invention described in claim 4, in the structure described in claim 1, the reflective layer has a thickness of 150 to
It is characterized by being a material that reflects 60% or more of ultraviolet rays in the wavelength range of 300 nm.

According to a fifth aspect of the present invention, in the first aspect, the reflective layer is formed in close contact with a part of the glass tube.

According to a sixth aspect of the present invention, in the first aspect, the reflection layer is formed separately on the outer peripheral portion of the glass tube in a flat or curved shape. To do.

The invention described in claim 7 is characterized in that, in the invention described in claim 1, at least a contact portion of the reflective layer with the light beam is a metal thin film.

According to the invention described in claim 8, in the invention described in claim 7, the metal thin film is aluminum.

According to a ninth aspect, in the first aspect, the phosphor is formed in close contact with a part of the glass tube.

In the invention described in claim 10,
The phosphor according to claim 1 is characterized in that the phosphor is separately formed on the glass substrate outside the glass tube.

In the invention described in claim 11,
The phosphor according to claim 4 or claim 9 is characterized in that the phosphor is formed on the entire portion of the glass tube where the reflective layer is not formed.

According to the invention described in claim 12,
In what was described in Claim 9 or Claim 11,
The phosphor is covered with a transparent moisture-proof protective layer.

[0022]

In the invention described in claim 1, the low-pressure mercury and the rare gas such as argon gas enclosed in the glass tube are converted into ultraviolet rays by the discharge of the discharge electrodes arranged at both ends of the glass tube. This ultraviolet ray is reflected by the reflection layer provided outside the glass tube. Then, the fluorescent material for converting the ultraviolet rays into visible light, which is applied to the surface of the glass tube on which the reflected ultraviolet rays strike, efficiently emits light.

In the invention described in claim 2, by limiting the material of the glass tube as specified, it is possible to increase the transmittance of ultraviolet rays having a wavelength effective for light emission, so that the light emission efficiency can be improved. Be raised as much as possible.

In the invention described in claim 3, since the glass tube is made of quartz glass, the transmittance of ultraviolet rays is kept high.

In the invention described in claim 4, the luminous efficiency is improved by setting the reflectance of ultraviolet rays to be high.

In the invention described in claim 5, ultraviolet rays are efficiently reflected by the reflective layer which is formed in close contact with a part of the glass tube.

In the invention described in claim 6, the flat or curved reflecting layer formed separately on the outer peripheral portion of the glass tube efficiently reflects ultraviolet rays.

In the invention described in claim 7, since at least the contact portion of the reflection layer with the light ray is the metal thin film, the light ray hitting this metal thin film is efficiently reflected and guided to the phosphor layer side. Get burned.

In the invention described in claim 8, since the metal thin film is aluminum, the reflection efficiency can be made extremely high.

In the invention described in claim 9, since the phosphor is formed in close contact with a part of the glass tube, the light emitting state does not change even if the discharge tube is replaced.

In the invention described in claim 10,
By forming the phosphor separately from the outside of the glass tube, the position of the phosphor with respect to the transparent resin substrate can be adjusted regardless of the position of the discharge tube.

According to the invention described in claim 11,
Since the phosphor is formed on the entire portion of the glass tube where the reflective layer is not formed, the generated ultraviolet rays effectively emit light.

In the invention described in claim 12,
By covering the phosphor with a transparent moisture-proof protective layer, it is less likely to be affected by ambient humidity.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. Reference numeral 18 indicates a discharge tube, which is shown in FIG.
It is used in place of the fluorescent tube 7 in FIG. The discharge tube 18 is made of a material which transmits 60% or more of ultraviolet rays in the wavelength range of at least 150 to 300 nm, and the inside 13 of the glass tube 11 is filled with a mixed gas of mercury and a rare gas, like the fluorescent tube 7. And electrodes on both ends (not shown)
It is a structure with. Transparent resin substrate 1 on the surface of discharge tube 18
The phosphor 12 is applied to a part of the surface facing the end face 6 side, and the moisture-proof protective layer 19 is formed on the surface. The moisture-proof protective layer 19 needs to be a transparent body that transmits visible light.

At least 150 is provided on the outer circumference of the discharge tube 18.
A reflection plate 20 that reflects 60% or more of ultraviolet rays in the wavelength range of up to 300 nm is placed. The reflecting plate 20 may be a thin layer of a reflecting material such as metal formed on a film as in the conventional example shown in FIG. 7, or may be made of only a metallic material having a smooth surface. Good.

Of the ultraviolet rays generated inside the discharge tube 18, the ultraviolet rays 14 that directly reach the phosphor 12 are visible light 15
Is converted into, and most of it reaches the end portion 6 of the transparent resin substrate 1. Further, the ultraviolet rays 16 that cannot directly reach the phosphor 12 are reflected by the reflection plate 20 on the outer periphery, finally reach the phosphor 12 and are converted into visible light 17, and most of them are end faces of the transparent resin substrate 1. 6 will be reached.

FIG. 2 shows a second embodiment of the present invention. Also in this embodiment, the structure of the discharge tube 18 and the reflection plate 20 provided on the outer periphery thereof are the same as those of the first embodiment, but the phosphor is not directly applied to the surface of the glass tube 11, but is a separate body. The phosphor plate 21 of is arranged. Phosphor plate 21
Is obtained by applying the phosphor 12 on a transparent glass or synthetic resin substrate 22 and forming a moisture-proof protective layer 19 on the surface thereof.

In this embodiment, the substrate 22 must be made of a material that transmits ultraviolet rays, and the moisture-proof protective layer 19 must be made of a material that transmits visible light. The substrate 22 and the moisture-proof protective layer 19 can be arranged in reverse, but in such a case, the substrate 22 is made of a material that transmits visible light.
Further, the moisture-proof protective layer 19 must be made of a material that transmits ultraviolet rays. Further, the phosphor plate 21 may be formed integrally with the end surface 6 of the transparent resin substrate 1. In this case, the phosphor 12 is applied on the end face 6 of the transparent resin substrate 1, and the moisture-proof protective layer 19 is formed on the surface. Also in the structure shown in this embodiment, the same effect as that of the first embodiment shown in FIG. 1 can be obtained.

FIG. 3 shows a third embodiment of the present invention. Also in this embodiment, the discharge tube 18 and the phosphor plate 2 are
The structure having 1 is the same as that shown in FIG. 2, but a reflection layer 23 made of a metal thin film is formed on a portion of the discharge tube 18 which does not face the phosphor plate 21. In this embodiment, the protective layer 24 is further added to the surface, but the protective layer 24 is not always necessary. Further, in the present embodiment, the reflector 20 shown in FIG. 1 is placed in at least one portion surrounding the discharge tube 18, but this reflector 20 is not always necessary if the area of the reflection layer 23 is large. .
Also in the structure shown in this embodiment, the same effect as that of the first embodiment shown in FIG. 1 can be obtained.

FIG. 4 shows a fourth embodiment of the present invention. In the present embodiment, the structure of the discharge tube 18 is basically the same as that shown in FIG. 1, but the reflection layer 23 made of a metal thin film is formed on the entire portion of the glass tube 11 of the discharge tube 18 which is not coated with the phosphor. The phosphor and the reflection layer 23.
The moisture-proof protective layer 19 is formed on the entire circumference of the surface. In addition,
In this embodiment, the reflector 20 shown in FIGS.
Although not provided, a structure in which this is added may be used.

In the embodiment described above, the discharge tube 18
Quartz glass is most preferable for the glass tube 11 because it has excellent ultraviolet ray transmission characteristics, but the present invention is not limited to this, as long as it is a material that transmits at least 60% of ultraviolet rays in the wavelength range of 150 to 300 nm. It can be used.
Further, as the metal material used for the reflection plate 20 or the reflection layer 23, aluminum is most preferable because of its high reflectance, but instead of this, at least 150 to 300
Any material that reflects 60% or more of ultraviolet rays in the wavelength range of nm can be used.

Although a side-light type structure has been described as a thin planar light source using the fluorescent lighting device of the present invention, the present invention is not limited to this, and the fluorescent tube is arranged directly below. It is also effective as an illuminating device for a so-called direct type surface light source, and can also be effectively applied to a field requiring a linear light source such as a drawing reading device.

The test of the present invention was carried out as follows, and it was possible to confirm high binding efficiency in all cases as compared with the conventional one.

Part 1: A quartz glass tube was filled with mercury and argon gas, and a discharge tube having electrodes on both ends was manufactured. A three-wavelength type rare earth phosphor is mixed in a vehicle (color-developing agent) to prepare a phosphor suspension, which is applied to the outer wall 1/3 of the quartz glass tube by a brush and applied at 500 ° C.
I baked at. Further, a moisture-proof coating material (CYTOP, manufactured by Asahi Glass Co., Ltd.) was applied to the surface of the portion where the phosphor was attached with a brush. Further, an aluminum plate whose surface was precisely polished was bent to form a reflecting plate, and the planar light source device shown in FIG. 1 was assembled.

Part 2: A quartz glass tube was filled with mercury and argon gas, and a discharge tube having electrodes on both ends was manufactured. A three-wavelength type rare earth phosphor is mixed in a vehicle (color-developing agent) to prepare a phosphor suspension, and a moisture-proof coating material (Cytop, manufactured by Asahi Glass Co., Ltd. ) Was applied with a brush. Further, an aluminum plate whose surface was precisely polished was bent to form a reflecting plate, and the planar light source device shown in FIG. 2 was assembled.

Part 3: A quartz glass tube was filled with mercury and argon gas, and a discharge tube having electrodes on both ends was manufactured. Masking the outer wall of the quartz glass tube 1/2 circumference,
Form a thin layer of aluminum by vacuum deposition, spray acrylic white paint on its surface,
Remove the masking. In addition, 3 to the vehicle (color-developing agent)
A wavelength type rare earth phosphor was mixed to prepare a phosphor suspension, which was applied to the surface of a quartz plate different from the quartz glass tube with a brush and baked at 500 ° C.
Further, a moisture-proof coating material (CYTOP, manufactured by Asahi Glass Co., Ltd.) was applied to the surface of the portion where the phosphor was attached by a brush. Further, an aluminum plate whose surface was precision-polished was bent to form a reflection plate, which was assembled as a planar light source device shown in FIG.

Part 4: A discharge tube having mercury and argon gas enclosed in a quartz glass tube and electrodes attached to both ends was manufactured. A three-wavelength type rare earth phosphor is mixed in a vehicle (color-developing agent) to prepare a phosphor suspension, which is applied to the outer wall 1/3 of the quartz glass tube by a brush and applied at 500 ° C.
I baked at. Further, masking is performed on a portion of the outer wall of the quartz glass tube where the phosphor is formed, and a thin layer of aluminum is formed by vacuum deposition, and then the masking is peeled off. Finally, a moisture-proof coating material (CYTOP, manufactured by Asahi Glass Co., Ltd.) was applied to the entire circumference surface of the quartz glass tube with a brush to assemble the planar light source device shown in FIG.

[0048]

The present invention is a fluorescent lighting device configured as described above, wherein a reflective layer for reflecting ultraviolet rays is formed outside the glass tube, and the surface of the glass tube exposed to the reflected ultraviolet rays is exposed to ultraviolet rays. Since it is coated with a phosphor for converting to visible light, when used in a thin planar light source device,
It is possible to obtain a light source that can guide the light into the transparent resin substrate more efficiently without the light rays reflected and returned to the inside of the tube being absorbed by the phosphor layer unlike the conventional fluorescent tube.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of a first embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of a second embodiment of the present invention.

FIG. 3 is a sectional view showing an essential part of a third embodiment of the present invention.

FIG. 4 is a sectional view showing an essential part of a fourth embodiment of the present invention.

FIG. 5 is a sectional view showing a basic structure of a conventional structure.

FIG. 6 is a cross-sectional view showing the basic structure of a fluorescent tube.

FIG. 7 is a sectional view showing a main part of a conventional device.

[Explanation of symbols]

 1 Transparent Resin Substrate 3 Anti-Swash Plate 5 Diffusion Plate 11 Glass Tube 12 Phosphor 13 Inside Glass Tube 14 UV 15 Visible Light 16 UV 17 Visible Light 18 Discharge Tube 19 Moisture Protective Layer 20 Reflector 21 Phosphor Plate 22 Substrate 23 Reflection Layer 24 Protective layer

Claims (12)

[Claims] 1. A low-pressure mercury gas and a rare gas such as argon gas are enclosed in a glass tube having a straight shape or at least one bent portion whose inside is kept airtight, and both ends of the glass tube are sealed. A discharge tube is formed by disposing discharge electrodes, a reflective layer that reflects ultraviolet rays is formed outside the glass tube, and the surface of the glass tube that is exposed to the reflected ultraviolet rays converts the ultraviolet rays into visible light. A fluorescent lighting device characterized in that a phosphor is applied. 2. A glass tube comprising at least 150-300.
The fluorescent lighting device according to claim 1, wherein the fluorescent lighting device is made of a material that transmits 60% or more of ultraviolet rays in a wavelength range of nm. 3. The fluorescent lighting device according to claim 1, wherein the material of the glass tube is quartz glass. 4. The fluorescent lighting device according to claim 1, wherein the reflective layer is made of a material that reflects 60% or more of ultraviolet rays in a wavelength range of 150 to 300 nm. 5. The fluorescent lighting device according to claim 1, wherein the reflective layer is formed in close contact with a part of the glass tube. 6. The fluorescent lighting device according to claim 1, wherein the reflective layer is formed separately on the outer peripheral portion of the glass tube in a flat or curved shape. 7. The fluorescent lighting device according to claim 1, wherein at least a contact portion of the reflective layer with the light beam is a metal thin film. 8. The fluorescent lighting device according to claim 7, wherein the metal thin film is aluminum. 9. The fluorescent lighting device according to claim 1, wherein the phosphor is formed in close contact with a part of the glass tube. 10. The fluorescent lighting device according to claim 1, wherein the phosphor is separately formed on the glass substrate outside the glass tube. 11. The fluorescent lighting device according to claim 4, wherein the phosphor is formed on the entire portion of the glass tube where the reflective layer is not formed. 12. The fluorescent lighting device according to claim 9, wherein the phosphor is covered with a transparent moisture-proof protective layer.