JP2007123085A - Rare gas fluorescent lamp and formation method of phosphor layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rare gas fluorescent lamp allowing thickness irregularity of a phosphor layer to be reduced by improving adhesiveness of a coating film of a phosphor; and to provide a formation method of a phosphor layer excelling in adhesiveness of the phosphor layer to a glass surface and capable of preventing the phosphor layer from being easily separated even when impact or the like is applied. <P>SOLUTION: This rare gas fluorescent lamp is characterized in that a porous base film formed by binding superfine particles each having a particle diameter not greater than 100 nm to one another is formed between an inside surface of an arc tube and the phosphor layer. This formation method of a phosphor layer is characterized by including processes of: preparing a suspension liquid with superfine particles dispersed therein by mixing a mixture solution of a Si alkoxide polymer, superfine particles of insulating powder each having a particle diameter not greater than 100 nm and an organic solvent; forming the porous base film with the superfine particles bound to one another by applying the suspension liquid of the superfine particles to a surface of a glass substrate and drying it; and applying a fluorescent substance to the glass substrate surface with the base film formed thereon by running down a suspension liquid with the fluorescent substance dispersed therein thereto. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rare gas fluorescent lamp, and more particularly to a method for forming a phosphor layer.

Conventionally, a lamp used in a backlight device such as a liquid crystal display body is one in which mercury and a rare gas are sealed in an arc tube made of an elongated glass tube, and a phosphor is coated on the inner surface. This is a so-called low-pressure mercury lamp provided with a pair of internal electrodes. Such a lamp excites a phosphor with ultraviolet rays of 254 nm obtained by low-pressure mercury vapor discharge to obtain visible light.
Lamps using such mercury have poor luminous flux rise characteristics at low temperatures, and because they use mercury with a large environmental load, recently, replacement with a low environmental load lamp that does not have such problems has been studied. It has been sought (see Patent Document 1).

  On the other hand, a rare gas fluorescent lamp that has been conventionally used favorably as a light source for illuminating a document does not use mercury, and excites a phosphor mainly with light from a low-pressure Xe gas discharge of about 5 to 10 kPa to emit light. It is a lamp. The structure includes an arc tube made of a dielectric material such as glass, and a pair of external electrodes extending in the length direction of the arc tube on the outer surface of the arc tube. A phosphor layer is formed on the inner surface of the tube. When a voltage is applied to the external electrode, a discharge with a dielectric interposed between the electrodes is generated, and as described above, emission of Xe gas having a wavelength of 172 nm is obtained, and this ultraviolet light excites the phosphor to make visible light. It is to be converted.

  The rare gas fluorescent lamp has good start-up characteristics and does not use mercury unlike a low-pressure mercury lamp, and is considered suitable from the viewpoint of environmental burden. Also, since mercury is not used in the lamp structure, there is no fear that the alkali component of the glass constituting the arc tube reacts with mercury, and it is not necessary to form a protective film on the inner surface of the arc tube.

JP-A-11-339729

Thus, when the rare gas fluorescent lamp is used for a so-called direct-type backlight light source or general illumination, it is necessary to extract the entire luminous flux and irradiate the light exit surface. And when a some lamp | ramp is arranged in parallel on the same plane, it is necessary to suppress the nonuniformity of a brightness | luminance in a light-projection surface.
For this reason, unlike the aperture-type structure that is common for document illumination, the phosphor is applied to the entire circumference of the tube, and the visible light formed in the arc tube is transmitted through the phosphor layer. A structure for extracting light is adopted. Therefore, in order to efficiently obtain the transmitted light from the phosphor layer, the phosphor layer is formed thinner than the one for illuminating the original, and the phosphor layer is formed without forming a reflective film. A structure that is directly applied to the glass tube constituting the arc tube is considered suitable.

Here, the phosphor coating process in the production of the rare gas fluorescent lamp will be briefly described.
First, a suspension is prepared by dispersing a powdery fluorescent substance in a butyl acetate solution in which a small amount of nitrocellulose is dissolved. The suspension in which the fluorescent material is dispersed is introduced into a long glass tube by a technique such as suction, and is applied by dropping naturally at an appropriate speed. Thereafter, the phosphor layer is finally formed through steps such as drying and baking.

  However, since the phosphor layer is a glass substrate having a smooth surface, the suspension of the fluorescent material is uniformly distributed due to various factors such as uneven wettability with the inner wall of the tube and uneven internal gas flow. It is difficult to form, and the phosphor film thickness is displaced by ± 10% or more in both the circumferential direction and the axial direction. For this reason, the thickness of the phosphor layer becomes non-uniform, and brightness unevenness may occur when the final rare gas fluorescent lamp is formed.

  In addition, since the fluorescent material has a smooth glass substrate surface, the fluorescent material has poor adhesion, and the phosphor layer may be easily peeled off with a slight impact.

The present invention has been made in view of the above circumstances, and an object of the present invention is to improve the adhesion of the phosphor coating film, to reduce thickness unevenness in the final phosphor layer, and to provide a rare gas fluorescent lamp. It is an object of the present invention to provide a rare gas fluorescent lamp with high uniformity of luminance distribution.
Furthermore, in the method for forming the phosphor layer on the glass substrate, the phosphor layer has good adhesion between the phosphor layer and the glass surface, and the phosphor layer is not easily peeled off even when an impact is applied. It is to provide a method.

In the present invention, the above problem is solved as follows.
It has a straight tubular arc tube in which a rare gas is enclosed and a phosphor layer is formed on the inner surface,
One electrode is formed on the outer surface of the arc tube in the longitudinal direction outside the arc tube, and the other electrode is formed with a dielectric interposed between the one electrode and the other electrode,
In a rare gas fluorescent lamp that emits excimer light in the arc tube by discharging through a dielectric between one and the other electrode,
A porous base film in which ultrafine particles having a particle size of 100 nm or less are bonded is formed between the inner surface of the arc tube and the phosphor layer.

Further, a siloxane bond is formed between the base film and the inner surface of the arc tube.
The ultrafine particles include any one of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , MgF ₂ , and AlN.

The phosphor coating method according to the present invention is a phosphor layer forming method for forming a phosphor layer on the surface of a glass substrate,
A step of preparing a suspension in which ultrafine particles are dispersed by mixing a mixed solution of Si alkoxide polymer, ultrafine particles of insulating powder having a particle size of 100 nm or less, and an organic solvent;
Applying a suspension of the ultrafine particles on the surface of the glass substrate and drying to form a porous base film formed by bonding the ultrafine particles;
And a step of applying a fluorescent material by flowing down a suspension in which the fluorescent material is dispersed on the surface of the glass substrate on which the base film is formed.

(1) Since the porous base film is formed on the surface of the glass tube, the fluorescent material is formed with a uniform thickness when the suspension of the fluorescent material is applied. The bonded state of the particles is good, and the fluorescent material is prevented from peeling off.
(2) Since a siloxane bond (-Si-O-) is formed between the base film and the glass tube, the bonding state between the base film and the glass tube surface is also good, and the phosphor layer is peeled off. There is no.
(3) By selecting from oxides such as SiO ₂ , Al ₂ O ₃ , ZrO ₂ , MgF ₂ , and AlN, fluorides, and nitrides, it is superior in chemical stability and availability. In particular, when SiO ₂ or MgF ₂ is used, these materials are preferable because they have a relatively low refractive index and can avoid reflection loss in the coating film.
(4) According to the method for forming a phosphor layer according to the present invention, since the solution of the Si alkoxide polymer is mixed with the suspension of ultrafine particles, the ultrafine particles are bonded together in a space, and the porous state A base film can be formed. Further, since a solution of the Si alkoxide polymer is used, a siloxane bond (—Si—O—) can be formed on the glass substrate, and the bond of the base film to the glass substrate surface becomes strong. Furthermore, since the suspension of the fluorescent substance is applied while the porous base film is formed, a phosphor layer having a uniform film thickness is obtained and the base film and the phosphor layer are bonded. Good condition is obtained.

  Hereinafter, although embodiment of this invention is described, this invention is not limited to this.

FIG. 1 is a diagram showing the configuration of a rare gas fluorescent lamp according to an embodiment of the present invention. FIG. 1 (a) is a perspective view of the rare gas fluorescent lamp according to the embodiment of the present invention, and FIG. 1 (b) is a rare gas fluorescent lamp. A sectional view of the lamp cut along a plane perpendicular to the tube axis is shown.
The arc tube 11 is made of translucent glass, and examples of the material thereof include soda lime glass, aluminosilicate glass, borosilicate glass, and barium glass. The dimensions of the tube are, for example, an inner diameter of 1.4 to 9.0 mm, an outer diameter of 2.0 to 10.0 mm, and a wall thickness of 0.3 to 0.5 mm. On the outer surface of the arc tube 11, a pair of strip-shaped electrodes 12 a and 12 b are arranged so as to extend in the length direction of the arc tube 11. These electrodes 12a and 12b are arranged so as to face each other in the cross-sectional view perpendicular to the tube axis shown in FIG.
The external electrodes 12a and 12b are not particularly limited as long as they are electrically conductive. For example, gold, silver, nickel, carbon, gold palladium, silver palladium, platinum, or the like can be suitably used. This is realized by sticking a tape-like metal to the outer surface of the arc tube 10 or screen-printing and baking a conductive paste.

  The arc tube 11 is filled with a rare gas of, for example, 30% Xe (xenon) and 70% Ne (neon) with a total enclosed pressure of 5 to 100 kPa. When applied, a discharge with a dielectric interposed between the external electrodes 12a and 12b is generated, and this discharge generates excimer molecular light emission by xenon.

  On the inner surface of the arc tube 11, a base film 14 having a porous structure in which ultrafine particles having an average particle size of 100 nm or less are bonded is formed, and the phosphor layer is laminated on the base film. 13 is formed. That is, prior to the application of the fluorescent material 13, the base film 14 is formed on the inner surface of the glass tube constituting the arc tube 11.

  As described above, since the porous base film 14 is formed on the surface of the arc tube 11, the fluorescent material is uniformly applied when the fluorescent material suspension is applied in the step of forming the fluorescent material layer 13. It is formed on the base film 14 with a thickness. And since the base film is made of a connective structure of ultrafine particles, it has surface characteristics different from a smooth surface such as glass, the phosphor particles are easily bonded to the base film 14, and the adhesion state is good. The peeling off is suppressed.

  As a phosphor for forming the phosphor layer 13, a known phosphor for a rare gas discharge lamp can be used. Specifically, a known phosphor such as a rare earth phosphor or a halophosphate phosphor is used. Substances can be used.

More specifically, the ultrafine insulating powder for forming the base film 14 is made of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , MgF ₂ , AlN or the like because of chemical stability or availability. Among them, SiO ₂ and MgF ₂ are particularly preferable because they have a small refractive index.
By using a material having a low refractive index as the base film 14 (specifically, a refractive index n = 1.5 or less), it is possible to avoid a visible light reflection loss when the lamp is used, and it is efficient. A lamp can be obtained.

In particular, when the base film 14 is formed, by using a Si alkoxide polymer, a —Si—O— siloxane bond is formed between the base film 14 and the glass substrate constituting the arc tube 11. The bond between the base film 14 and the glass substrate becomes stronger.
Therefore, there is no problem that the phosphor layer 13 is peeled off from the arc tube 11 together with the base film 14.

  According to the rare gas fluorescent lamp according to the present invention described above, vacuum ultraviolet light having a wavelength of 172 nm obtained by excimer emission is excited by irradiating the fluorescent material in the phosphor layer 13 to emit visible light. Most of the visible light is reflected by the phosphor layer 13, and the reflected light passes through the phosphor layer 13 and the base film 14 at the opposing portion with a certain probability and is emitted to the outside of the arc tube 11.

Here, a method for forming a phosphor layer according to the present invention will be described with reference to the drawings.
[1]
A suspension in which ultrafine particles are dispersed is prepared by mixing ultrafine particles of an insulating powder having a particle size of 100 nm or less, an organic solvent, and a mixed solution of an Si alkoxide polymer.
[2]
This ultrafine particle dispersion suspension is applied to the surface of a glass tube for arc tube construction and dried.
As shown in FIG. 2 (a), immediately after the suspension is applied, the suspension contains a solution of the Si alkoxide polymer, so that the -O-Si-O-siloxane bond of the same element is formed on the surface of the glass substrate 30. Is formed, and the coating film is firmly adhered to the glass substrate 30.
FIGS. 2B and 2C are views in which the surface of the glass substrate 30 is observed more macroscopically than in FIG. The viscosity of the suspension increases rapidly due to the increase in concentration due to evaporation of the solvent and further polymerization of the Si alkoxide. When ultrafine particles are blended, the ultrafine particles 31 are randomly floating in the solvent as shown in (b), but in the drying process after coating, the viscosity of the liquid increases rapidly due to evaporation of the solvent. For this reason, it is fixed and hardened before the closest filling (FIG. 2C).
The binder composed of the organic solvent and the Si alkoxide polymer finally becomes a dense and hard glassy cured product.
In this way, the base film 14 having a porous structure is formed.
Since Si alkoxide finally becomes SiO ₂ after drying, it is a substance of the same quality as SiO ₂ which is the main component of glass, and is strong in Si—O and —Si—O—Si— of substrate glass 30. It is considered that the adhesion of the base film 14 is strengthened by forming a siloxane bond.
[3]
After the base film 14 is formed, a suspension in which a fluorescent material is dispersed on the surface of the glass substrate 30 is prepared and allowed to flow down to form a coating film.
FIG. 3 is a diagram explaining this situation. When the suspension in which the fluorescent material 32 is dispersed is caused to flow down on the base film 14, a part of the solvent penetrates between the ultrafine particles 31, and the fluorescent material 32 floating in the solvent is on the base film 14. accumulate. The fluorescent material 32 is locked to the irregularities formed by the ultrafine particles 31 of the base film 14 and stably adheres, so that the fluorescent material 32 is applied in a substantially uniform state, and there is no unevenness in thickness. A coating film can be formed.
[4]
After that, when the coating film of the fluorescent material 32 is dried and baked in a predetermined atmosphere and temperature, simple molecules such as CO ₂ and H ₂ O are decomposed and volatilized, and finally formed by the ultrafine particles 31. A glass substrate 30 in which the phosphor layer 15 is formed in a laminated state on the porous base film 14 is obtained.

  In the above, in the suspension in which the ultrafine particles are dispersed, when the binder content decreases, the amount of the ultrafine particles bonded to each other decreases, the strength of the cured body decreases, and it is used for bonding to the glass. It is considered that the amount of the binder also decreases, and the adhesion between the glass tube and the coating film decreases. Therefore, it is considered that there is a condition that the mixing ratio is appropriate.

In the case where the Si alkoxide polymer is not used, the film is dried densely as shown in FIG. In this case, when forming the fluorescent material coating film, the base film does not absorb the solvent, is not much different from the state in which the fluorescent material is directly applied to the surface of the glass substrate, and the thickness of the fluorescent material coating film is not uniform. become. In addition, the fluorescent material may fall off after the phosphor layer is formed and the lamp is manufactured.
Furthermore, since a cycloxan bond is not formed between the base film and the glass substrate, the adhesion between the base film and the glass substrate is also inferior to that of the present invention.

As described above, according to the rare gas fluorescent lamp of the present invention, the porous base film composed of SiO ₂ and the ultrafine particles of the insulating material is interposed between the glass tube and the phosphor layer constituting the arc tube. Since it is formed, the thickness of the phosphor coating film can be made uniform in the phosphor powder coating process, so that the phosphor layer obtained after the main baking is well bonded to the base film and easily peeled off. There is nothing wrong. Further, since the base film is formed using Si alkoxide, it is possible to obtain a strong bond between SiO ₂ in the base film and the glass constituting the arc tube, and the base film can be easily peeled off. Absent. Therefore, in the rare gas fluorescent lamp as the final product, the thickness of the phosphor layer is substantially constant, and the occurrence of uneven brightness when the lamp is lit can be suppressed.

  As described above, the present invention has been described in detail. However, the present invention is not limited to the above-described embodiment, and it is needless to say that changes can be made as appropriate. It does not matter.

  Hereinafter, the phosphor layer was formed by the manufacturing method according to the present invention. Hereinafter, although an experiment example is demonstrated, this invention is not limited to this content.

<Experimental example 1>
(1) Preparation of dip coat (undercoat film) solution 350 g of tetraethyl orthosilicate (chemical formula: Si (OC ₂ H ₅ ) ₄ ), 1030 g of ethanol, 330 g of acetic acid, and 0.6 g of hydrochloric acid were placed in a reflux flask and stirred well. Thereafter, the mixture was refluxed with a mantle heater for 12 hours to prepare a Si alkoxide polymer solution.
This polymerization solution and SIAI Kasei SIAP 10 wt% -X360 solution (trade name) are mixed at a weight ratio of 1: x (where x is 0 to 15.0), and ethyl acetate is added to the mixture by weight. The mixture was mixed at a ratio of 1: 1 to prepare a suspension in which ultrafine particles for forming the base film were dispersed.
Although manufactured by CI Kasei Co., SIAP10wt% -X360 solution is an ultra-fine particles of CI Kasei Co., of SiO _2, and SiO ₂ ultrafine particles are sold also from other companies, for example catalyst Chemical Industry Co., Ltd. of Oscar series, Nissan Chemical Industries, Ltd. of Snowtex series It is. Other ultrafine particles can be easily obtained from CII Kasei Co., Ltd. such as Al ₂ O ₃ , ZrO ₂ , ZnO. The porosity varies depending on the size of x to be blended.
(2) Formation of base film The previously prepared suspension of ultrafine particles was coated on the inner surface of a glass tube having an outer diameter of 8 mm, a wall thickness of 0.4 mm, and a length of 100 mm using a dipping / pulling method. When this pulling speed is changed, the film thickness changes. Here, it pulled up at a pulling speed of 4 to 5 mm / sec. Thereafter, it was dried at about 150 ° C. to obtain a hard coat film having a thickness of 100 to 200 nm.
(3) Preparation of phosphor slurry An appropriate amount of phosphor powder was mixed in a small amount of a mixed solution of nitrocellulose and butyl acetate to prepare a suspension in which the phosphor was dispersed so that the viscosity was 15 centipoise. The resulting suspension was an emulsion dispersion.
(4)
This phosphor slurry was applied to the inner surface of the glass tube on which the previously formed base film was formed. The application method was a suction / natural drop method.
(5)
After drying at 200 ° C. for 10 minutes, main baking was performed at 500 ° C. for 20 minutes.

The thickness of the phosphor layer formed on the inner surface of the glass tube was measured at a total of 12 measurement points per sample, and the standard deviation was obtained to measure the degree of variation in the phosphor film thickness. Four measurement points were collected at regular intervals in the circumferential direction at three axial positions of both ends and the center of the glass tube. In measuring the film thickness, the tube was cut and the cross section was enlarged with an optical microscope. The evaluation of adhesion was evaluated as ◯ when it was easily peeled off with linen, x was peeled off easily, Δ was partially peeled off, Δ was not peeled off at all.
The variation in film thickness is a standard deviation of 12 measurement points per sample, 2σ.

FIG. 3 shows a variation state of the phosphor layer when the mixing ratio of the SiO ₂ ultrafine particles is changed.
If there is no SiO ₂ ultrafine particles, or if the amount is too small, the phosphor layer will vary widely, and if it is too large, that is, if the amount of the Si alkoxide polymerization solution is too small, the adhesion will be reduced. According to this example, when a 10 wt% solution of SiO ₂ is used, the optimum range of the mixing ratio with respect to the mixing of the Si alkoxide polymerization solution of the above specifications is from 0.5 to the Si alkoxide polymer solution. It was found to be in the range of 10.

  The above embodiment is merely an example for carrying out the present invention, and it goes without saying that it can be changed as appropriate.

It is the perspective view and sectional drawing of the noble gas fluorescent lamp concerning this invention. It is explanatory drawing explaining the formation method of the base film concerning this invention. It is explanatory drawing explaining the formation method of the fluorescent substance layer concerning this invention. It is a figure which shows typically the deposition state of the ultrafine particle in the case of not using Si alkoxide polymerization liquid. It is a table | surface which shows the result of an Example collectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Arc tube 12a, 12b External electrode 13 Base film 14 Phosphor layer 20 Lighting power source 30 Glass base material 31 Ultrafine particle 32 Fluorescent substance

Claims (4)

It has a straight tubular arc tube in which a rare gas is enclosed and a phosphor layer is formed on the inner surface,
One electrode is formed on the outer surface of the arc tube in the longitudinal direction outside the arc tube, and the other electrode is formed with a dielectric interposed between the one electrode and the other electrode,
In a rare gas fluorescent lamp that emits excimer light in the arc tube by discharging through a dielectric between one and the other electrode,
A rare gas fluorescent lamp, wherein a porous base film in which ultrafine particles having a particle size of 100 nm or less are bonded is formed between the inner surface of the arc tube and a phosphor layer.   The rare gas fluorescent lamp according to claim 1, wherein a siloxane bond is formed between the base film and the inner surface of the arc tube. _2. The rare gas fluorescent lamp according to claim 1, wherein the ultrafine particles include any one of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , MgF ₂ , and AlN. A method for forming a phosphor layer that forms a phosphor layer on the surface of a glass substrate,
A step of preparing a suspension in which ultrafine particles are dispersed by mixing a mixed solution of Si alkoxide polymer, ultrafine particles of insulating powder having a particle size of 100 nm or less, and an organic solvent;
Applying a suspension of the ultrafine particles on the surface of the glass substrate and drying to form a porous base film formed by bonding the ultrafine particles;
And a step of applying a fluorescent material by flowing a suspension in which the fluorescent material is dispersed onto the surface of the glass substrate on which the base film is formed.

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