JPH07153435A - Bulb - Google Patents

Abstract

PURPOSE:To prevent peeling-off of a coating film so as to enhance efficiency irrespective of the shape of a bulb by specifying an optical film thickness of each metal oxide film in the bulb where the metal oxide films of high and low refraction factors are laminated alternately. CONSTITUTION:First metal oxide films 5H1-5H17 each exhibiting a high refraction factor and second metal oxide films 5L2-5L18 each exhibiting a low refraction factor are laminated alternately on the outer surface of a glass bulb 1 sealing a filament therein, thus forming a multilayer light interference film. In this bulb, each of the first metal oxide film 5H1-5H17 has an optical film lambda/2 thick while each of the second metal oxide films 5L2-5L18 is lambda/4 thick. Consequently, it is possible to prevent generation of a crack or peeling-off of a coating film in the case where a non-cylindrical bulb likely affected in a soaking method is coated with a film, to thus provide a bulb having enhanced light emitting efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light bulb in which a multilayer optical interference film having a visible light transmitting and infrared reflecting function is formed on the surface of a glass bulb such as a halogen bulb.

[0002]

2. Description of the Related Art Various efforts have been made in the field of light bulbs as part of energy saving. For example, in a halogen light bulb, a multilayer light interference film having a visible light transmitting and infrared reflecting effect is formed on the surface of a bulb. It is known that visible light emitted from the filament is transmitted through the bulb, and infrared light is reflected by the light interference film and returned to the filament, thereby heating the filament and increasing luminous efficiency.

As such a light interference film having a visible light transmitting / infrared reflecting function, a titanium oxide (TiO ₂ ) film having a high refractive index and a silicon oxide (SiO ₂ ) film having a low refractive index are used. By alternately stacking layers to form multiple layers and appropriately selecting the number of layers and the thickness of the layers, light interference is utilized to selectively transmit and reflect light in a desired wavelength range.

In this light bulb, the larger the number of layers of the film, the higher the reflectance of infrared rays and the greater the effect of power saving.

Generally, this optical interference film having a visible light transmitting infrared reflecting action is a so-called λ / 4 optical interference film, and its wavelength λ is adjusted to the peak wavelength (in the vicinity of 1 μ) of infrared radiant energy of the bulb filament. However, when forming films having the same film thickness, the film forming operation is easy and is often adopted.

However, in view of the recent energy situation, there is a demand for further energy saving and high efficiency of the light bulb.
By selecting the material of the light interference film, the number of film layers, the film thickness of each layer, and the forming method, it has become possible to obtain a light bulb of higher quality. In addition, as a method of forming this optical interference film,
The immersion method has been widely adopted due to cost reasons.

In this dipping system, for example, a titanium solution obtained by reacting an organic titanium compound such as tetraisopropyl titanate with acetylacetone or polyethylene glycol and dissolving it in an ethanol-based solvent and an organic silicon compound such as an ethyl silicate polymer are similarly prepared. A multi-layer film was formed using a silicon solution.

However, in such a multilayer film, when the number of layers is increased, the film is cracked or peeled between layers due to the strain due to the difference in the coefficient of thermal expansion between the materials. In the case of forming the multilayer coating shown, the limit was about 14 layers.

That is, FIG. 6 schematically shows a conventional visible-light-transmitting infrared-reflecting film, and a titanium oxide (TiO ₂ ) film showing a high refractive index and an oxidizing film showing a low refractive index from the surface side of the bulb 1 (glass). It is a layer in which silicon (SiO ₂ ) films are alternately laminated by a dipping method. Each of these films is made of titanium oxide (TiO ₂ ) forming a high refractive index layer on the first to thirteenth layers on the buffer film 6 which will be described later formed on the surface of the bulb 1.
The films 5H1 to 5H13 have an optical film thickness of λ / 4, and the second and fourth layers are made of silicon oxide (S
iO ₂ ) films 5L2 and 5L4 have an optical film thickness of λ / 2,
The silicon oxide (SiO ₂ ) films 5L6 to 5L12 forming a low refractive index layer have an optical film thickness λ / 4 in the first to twelfth layers, and the oxidation forming a low refractive index layer in the outermost layer of the fourteenth layer. Silicon (S
The iO ₂ ) film 5L14 is formed with an optical film thickness of λ / 8.

The buffer film 6 is made of quartz glass forming the bulb 1 and titanium oxide (Ti) forming a high refractive index layer.
It is a silicon oxide (SiO ₂ ) film having an optical film thickness of λ / 8, which has an intermediate coefficient of thermal expansion with that of O ₂ ), and has a refractive index close to that of the glass of the bulb 1 and an optical film thickness of the wavelength of the target light. It is smaller than 1/4 and relaxes the strain due to the difference in coefficient of thermal expansion without changing the optical characteristics of the optical interference film.

The silicon oxide (SiO ₂ ) film 5L, which constitutes the low refractive index layer by the above-mentioned film formation by dipping, has a limit in the film thickness that can be formed by one dipping, and the second layer film is formed. In order to form the λ / 2 film of the 5L2 and the fourth-layer coating 5L4, it is necessary to form the λ / 4 film by stacking it twice.

However, this silicon oxide (SiO ₂ ) film has a strong compressive intrinsic stress (stress due to the fine structure of the film depending on the method of forming the film) (40-60 megapascals according to the literature), and the layer The strain increases as the number increases, and when the film strength (intra-film interface) is exceeded, cracks start from the defective portion in the film, and the cracks rise to cause peeling. Silicon oxide (SiO ₂ )
Since the intrinsic stress of the film 5L depends on the number of times of dip coating,
The maximum number of layers that can be stacked is about 14 layers.

Particularly, in the case of a valve having a complicated curved surface such as a spheroidal shape or a non-cylindrical valve having a small curvature and a large anisotropy, cracks or peeling occur in the film around a portion slightly deviated from the center of the center. It starts to work and is more affected than a cylindrical valve.

[0014]

SUMMARY OF THE INVENTION In consideration of the film thickness limit of the immersion method, the present invention can remove the coating film not only on a cylindrical valve but also on a non-cylindrical valve which is easily affected by the immersion method. It is an object of the present invention to provide a halogen light bulb that can improve efficiency without the need.

[0015]

According to a first aspect of the present invention, there is provided a light bulb having a first metal oxide film having a high refractive index and a second metal oxide film having a low refractive index on an outer surface of a glass bulb in which a filament is sealed. In the electric bulb in which the multilayer optical interference film is formed by alternately laminating the metal oxide films of the above, one of the first metal oxide films has an optical film thickness of λ / 2 and a second metal oxide film of It is characterized in that the optical film thickness is λ / 4.

The light bulb according to claim 2 of the present invention is characterized in that the optical film thickness of the outermost layer of the multilayer optical interference film is λ / 8.

According to a third aspect of the present invention, the bulb has a cylindrical shape.

A light bulb according to a fourth aspect of the present invention is characterized in that the bulb has a non-cylindrical shape.

A light bulb according to a fifth aspect of the present invention is characterized in that a halogen is enclosed.

[0020]

[Function] Since the silicon oxide (SiO ₂ ) film forming the visible light transmitting infrared reflecting film has a high compressive stress, the film thickness of each layer is made the same, and the film thickness on the titanium oxide (TiO ₂ ) film side having a strong tensile stress is used. By relieving the stress of both films,
Even if the tensile stress is reduced and the number of coating layers is increased, cracks are unlikely to occur in the coating and cracks and peeling do not occur, and
The transmittance of visible light is high and the reflectance of infrared light is also high, so that the luminous efficiency can be improved.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a halogen light bulb L. In FIG. 1, reference numeral 1 denotes a cylindrical bulb made of quartz glass, in which a filament 2, a halogen compound and an inert gas such as argon are enclosed. The filament 2 is supported by the inner conductors 3a and 3b and the anchor 4, and
Are arranged along the central axis of the. In addition, 7 is a valve 1
It is a base joined to the end of.

Reference numeral 5 is a visible light transmitting infrared reflecting film composed of a multilayer optical interference film formed on the buffer film 6 on the outer surface of the bulb 1 corresponding to the portion where the filament 2 is disposed. The visible light transmitting / infrared reflecting film 5 (hereinafter referred to as "red film") is, for example, an oxide showing a high refractive index from the buffer film 6 on the outer surface of the bulb 1 (glass) as shown in FIG. First metal oxide film 5 made of titanium (TiO ₂ )
H ... and low refractive index such as silicon oxide (SiO ₂ )
The second metal oxide film 5L ... Is alternately laminated to form a total of, for example, 18 layers.

The optical film thickness of each of these layers is, for example, a titanium oxide (TiO ₂ ) film (an odd number of 5H1 to 5H17) forming a high refractive index layer formed on the surface of the buffer film 6 as the first layer 5H1, for example, the 9th layer. Λ / 2 up to 5H9, 11th layer 5H
Λ / 4 from the 11th to the 17th layer 5H17, and a silicon oxide (SiO ₂ ) film (5L2 to 5L5) forming a low refractive index layer.
L18 even number) is λ / 4 from the second layer 5L2 to the 16th layer, and λ / 8 is the outermost 18th layer.

In order to form the red film 5 and the buffer film 6 as described above, first, the bulb 2 is sealed in the bulb 1, exhausted, and a light bulb in which halogen and an inert gas are sealed is prepared. To do. Separately, a titanium solution prepared by reacting an organic titanium compound such as tetraisopropyl titanate with acetylacetone or polyethylene glycol to dissolve it in an ethanol-based solvent to a titanium content of 2 to 10% by weight and a viscosity of about 2.0 cps, An organic silicon compound such as an ethyl silicate polymer is dissolved in an organic solvent to have a silicon content of 2 to 10% by weight and a viscosity of about 1.
Prepare a silicon solution adjusted to 0 cps.

First, the bulb 1 of the electric bulb is immersed in the silicon solution described above in a constant temperature and constant humidity atmosphere, pulled up at a predetermined speed, dried and then baked in air at about 700 ° C. for 10 minutes to obtain silicon oxide. A buffer film 6 made of a (SiO ₂ ) film and having an optical film thickness of λ / 8 is formed.

Next, the valve 1 in which the buffer film 6 is formed
Is immersed in the above titanium solution in a constant temperature and constant humidity atmosphere, pulled up at a predetermined speed, dried, and then baked in air at about 700 ° C. for 10 minutes to form a first layer of titanium oxide (TiO ₂ ) film 5H1.
To form a high refractive index layer.

Next, the titanium oxide (Ti
O ₂ ) The valve 1 having the film 5H1 formed thereon is dipped in the above silicon solution in a constant temperature and constant humidity atmosphere, pulled up at a predetermined speed, dried and then baked in air at about 700 ° C. for 10 minutes to form a second layer. Low-refractive-index layer 5L made of a silicon oxide (SiO ₂ ) film
Form 2.

In this way, titanium oxide (TiO ₂ )
High refractive index layer made of film 5H ... and silicon oxide (SiO ₂ )
18 layers (5H1, 5L2 to 5H17, 5L18) are laminated by alternately forming low refractive index layers made of films 5L.

In the film formation by the above-mentioned dipping, there is a limit to the film thickness that can be formed by one dipping, and it is necessary to form the λ / 2 film twice as a double layer to form the λ / 2 film.

As described above, the silicon oxide (SiO ₂ ) films 5L ... Which constitute the low refractive index layer have a strong compressive intrinsic stress, and the λ / 4 film is formed twice when forming the λ / 2 film. When forming multiple layers, cracks and peeling were likely to occur in the coating.

On the other hand, in the present invention, silicon oxide (Si
O ₂ ) film 5L ... is applied less frequently, and the titanium oxide (TiO ₂ ) film 5H ... by dipping is weakly formed (1/10 or less of the silicon oxide (SiO ₂ ) film). Since it has a tensile stress opposite to that of the silicon (SiO ₂ ) film 5L, the stress of the entire film is relaxed as the number of times of coating of titanium oxide (TiO ₂ ) is increased, and there is no occurrence of cracks or peeling in a balanced manner. , The number of layers can be increased. Λ / 2 of titanium oxide (TiO ₂ ) film using the same solution as above
It was also possible to form 18 times or more and coat 18 layers.

When the light bulb L having such a configuration is turned on, the filament 2 arranged on the central axis of the bulb 1 generates heat and emits a large amount of infrared rays together with visible light, and the filament 2
Visible light among the light emitted from the bulb 1 and the red anti-membrane 5
Is emitted to the outside of the bulb 1. Further, the infrared rays emitted from the filament 2 are reflected by the red anti-reflection film 5 and return to the filament 2 to heat the filament 2 to further increase the light emission. As a result, the visible light emission from the filament 2 is increased and the luminous efficiency is increased. I was able to improve.

When the number of layers of the coating layer of the present invention is the same as the above-mentioned conventional 14 layers, the luminous efficiency is reduced by about 10% as compared with the conventional bulb, but the number of coating layers is 1.
Even with 8 layers, it is a strong coating that does not peel off, and the luminous efficiency of the conventional coated product is improved by about 25% compared to the light bulb in which the red coating 5 is not formed, whereas the coated product of the present invention exceeds the conventional coated product. We were able to see an improvement of about 34%.

Next, the optical characteristics of the product of the present invention and the conventional product are shown in the graph of FIG. In FIG. 3, the horizontal axis indicates the wavelength (n
m), the vertical axis is the light transmittance (%), and the curve A shows the light transmittance / spectral characteristics of the product of the present invention, and the curve B shows the light transmittance / spectral characteristics of the conventional product.

As is clear from FIG. 3, the red film applied to the light bulb of the present invention is almost the same as the conventional product in the visible light range, but the transmittance is lowered in the infrared range (1000 nm or more) and the infrared reflection is caused. The luminous efficiency was improved because the filament efficiency was increased and the filament was heated.

When the red anti-reflection film 5 is composed of all 18 layers, titanium oxide (TiO ₂ ) 5H having the above high refractive index is formed.
When the number of layers of the film having an optical film thickness of λ / 2 was variously changed and the change in efficiency was examined, the results shown in FIG. 4 were obtained.
In FIG. 4, the horizontal axis represents the number of layers of λ / 2, and the vertical axis represents the improvement rate of the luminous efficiency (Lm / W) (assuming that the efficiency of a light bulb that does not form a red anti-reflection film is 0%). As is clear from the figure, λ / 2
The luminous efficiency (Lm / W) was improved by forming the layers, and the case of 5 layers among the 18 layers was the best, but in the experiment of the inventor, it was found that λ /
It was confirmed that it is necessary to increase the number of layers of 2, and the more the number of layers, the more the efficiency can be improved. Further, when the λ / 2 layer is formed on the outermost layer side, the stress up to that time is accumulated, and the disorder of the film increases, and when a thick film is formed on the film, peeling occurs. Is preferably formed on the side closer to the valve, that is, on the first layer side.

The present invention is not limited to the above embodiment. For example, the number of layers of the high refractive index layer, the low refractive index layer and the λ / 2 layer constituting the visible light transmitting infrared reflecting film is 18 in the total number of layers in the above embodiment and 5 in the λ / 2 layer. It is not limited.

The material of the first metal oxide film having a high refractive index is not limited to titanium oxide (TiO ₂ ) but tantalum oxide (Ta ₂ O ₅ ) and zirconium oxide (Zr).
O ₂ ), zinc oxide (ZnS), etc., and silicon oxide (S) as a material for the second metal oxide film exhibiting a low refractive index.
It is not limited to iO ₂ ) and may be magnesium fluoride (MgF) or the like.

In the above-mentioned embodiment, the buffer film is previously formed on the outer surface of the valve. However, the buffer film is not essential and it is not necessary that the materials have a small difference in coefficient of thermal expansion.

Further, the light bulb is not limited to a light-emitting halogen light bulb in which a sealing portion is formed at one end of a bulb, but may be a light bulb of other type or a type in which halogen is not enclosed. It is used by being installed in a reflecting mirror or a variety of lighting fixtures on which a visible light reflecting infrared ray transmitting film such as a reflecting film or a dichroic film is formed. Alternatively, the bulb may be a double-ended bulb in which the sealing portions are provided at both ends of the bulb.

Further, the glass material of the bulb is not limited to quartz glass, and any other hard or soft glass material may be used as long as it has the required translucency, optical refractive index and heat resistance. Furthermore, the present invention is not limited to the light bulb L using the above-mentioned cylindrical bulb 1, and may be a light bulb using a non-cylindrical bulb 1 having a spheroidal shape or a spherical shape as shown in FIG. Of course, the formation of the coating film on the valve 1 having such a curved surface may be adjusted by changing the pulling rate of the valve 1 immersed in the solution according to the state of the curved surface to adjust the film thickness.

[0042]

As described above in detail, according to the present invention, a multiple light interference film (visible light transmitting infrared reflecting film) is coated on a cylindrical valve as well as a non-cylindrical valve which is easily affected by the dipping method. Even in such a case, it is possible to provide a light bulb in which the stress is relieved, the coating film is not cracked or separated, and the luminous efficiency is improved.

[Brief description of drawings]

FIG. 1 is a front view of a halogen bulb for floodlight showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a visible light transmitting infrared reflecting film portion of FIG.

FIG. 3 is a graph showing the relationship between wavelength and light transmittance.

FIG. 4 is a graph showing the relationship between the number of λ / 2 layers having an optical film thickness of a high refractive index layer and efficiency.

FIG. 5 is a front view of a halogen light bulb according to another embodiment of the present invention.

FIG. 6 is an enlarged cross-sectional view showing a visible light transmitting infrared reflecting film portion of a conventional product.

[Explanation of Codes] L: Light Bulb 1: Glass Bulb 2: Filament 5: Multilayer Optical Interference Film (Visible Light Transmitting Infrared Reflecting Film) 5H1 to 5H17: First Metal Oxide Film (High Refractive Index Layer) 5L2 to 5L18: Second metal oxide film (low refractive index layer) 6: Buffer film

Claims (5)

[Claims] 1. A multilayer optical interference film in which a first metal oxide film having a high refractive index and a second metal oxide film having a low refractive index are alternately laminated on the outer surface of a glass bulb in which a filament is sealed. In the light bulb having the above-mentioned structure, one of the first metal oxide films has an optical film thickness of λ / 2, and the second metal oxide film has an optical film thickness of λ / 4. 2. The light bulb according to claim 1, wherein the outermost layer of the multilayer optical interference film has an optical film thickness of λ / 8. 3. The light bulb according to claim 1, wherein the bulb has a cylindrical shape. 4. The light bulb according to claim 1, wherein the bulb has a non-cylindrical shape. 5. A light bulb according to claim 1, wherein the light bulb is filled with halogen.