This invention relates to a high intensity lamp capable of radiating an illuminating light generated from a bright light source to a side of a face to be illuminated after an ultraviolet ray component thereof has effectively been cut-off.

BACKGROUND ART Recently, there have been many cases wherein a high intensity lamp such as a halogen lamp having a heat radiating light source or a metal halide lamp having a luminescence light source, is employed as a head lamp or a fog lamp for an automobile, or a lamp for spot illumination such as in a display illumination or in a projection-type liquid crystal TV set.

Furthermore, in the high intensity lamp employed as above, as a bulb glass or a front glass for a bulb constituting the high intensity lamp, a glass is normally employed which allows transmission of an ultraviolet light ray having a wavelength in a range of 250 through 400 nm, such as quartz glass, borosilicate glass, or aluminium silicate glass.

Furthermore, in the high intensity lamp, with the promotion of a function thereof, a density of the

illuminating light has gradually been increasing. Corresponding thereto an illumination density of the ultraviolet light ray radiated from a light source tends to increase all the more. On the other hand, in recent automobiles, there is a strong requirement of design in which aerodynamic resistance on a car surface is reduced. As a result,, with respect to the head lamp or the fog lamp, a construction is often adopted wherein an outer cover made of a synthetic resin having a face height the same with that of the car surface is covered thereon.

In case of employing the high intensity lamp, an excellent effect can be provided wherein the side of the face to be illuminated can be illuminated by the illuminating light brighter than in a conventional case. However, in case of employing the high intensity lamp of this kind in the head lamp of an automobile or the lamp for spot illumination as in the display illumination or the projection-type liquid crystal TV set, with increase of the illuminating density of the illuminating light, an ultraviolet light ray of which illuminated density is increased, transmits through the bulb glass or the front glass of a bulb. Accordingly, for instance, the outer cover which covers the car surface of an automobile, a display material composed of textiles such as a clothing which is disposed at the face to be illuminated, or a liquid crystal panel which is

essentially apt to be deteriorated by the ultraviolet light ray, is exposed to the ultraviolet light ray having high density. Therefore, there is an inconvenience wherein the transmitted ultraviolet light ray deteriorates quality and function of a member disposed at the face to be illuminated, or wherein colors thereof are faded. Furthermore, since a light ray having a wavelength of not more than 315 nm is particularly poisonous to a human body, an improvement is desired in view of safety.

DISCLOSURE OF INVENTION It is an object of the present invention to provide a high intensity lamp capable of radiating an illuminating light on a face to be illuminated after cutting-off an ultraviolet light ray thereof effectively, in view of the above problems in the conventional technology.

According to an aspect of the present invention, there is provided a high intensity lamp which radiates an illuminating light generated from a heat radiating light source or a luminescence light source to a side of a face to be illuminated by transmitting the illuminating light through a bulb glass and/or a front glass of a bulb, wherein the bulb glass and/or the front glass of a glass is or are formed by a glass provided with an ultraviolet light ray cutting-off function having a cutting-off limit in a wavelength range of 350 through 430 nm and a width

of cutting-off inclination of not larger than 20 nm.

According to the present invention, the illuminating light generated by the light source of the high intensity lamp radiates the face to be illuminated after effectively cutting-off the ultraviolet light ray component thereof by the bulb glass and/or the front glass of a bulb. Therefore, the member disposed on the side of the face to be illuminated is protected from a ultraviolet ray hazard such as color fading or quality deterioration, durability thereof is promoted and bad influence on the human body can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a partially cut-off sectional diagram of a high intensity lamp integrated with a halogen lamp according to the present invention;

Figure 2 is an enlarged front diagram of the halogen lamp in Figure 1;

Figure 3 is a front diagram of a metal halide lamp of this invention; and Figure 4 is a graph comparing situations of cutting- off ultraviolet light ray components of a high intensity lamp formed by using a bulb glass composing this invention and a high intensity lamp formed by using a conventional bulb glass. BEST MODE FOR CARRYING OUT THE INVENTION

A detailed explanation will be given of embodiments of this invention referring to the drawings, as follows.

A high intensity lamp 11 shown in Figure 1, is integrated with a halogen lamp. In the halogen lamp, as shown in Figure 2 in details, an enclosed gas such as inert argon, iodine, bromine and the like, are enclosed in a bulb glass 12 having a base 21, a tungsten filament 15 glows and a light having high density generated by the glow, can be radiated. The light radiated by the halogen lamp, is reflected by a reflecting face 13, and transmits through a front glass 14 of the bulb by which the light is condensed, thereby enabling to be radiated to the side of a face to be illuminated.

Furthermore, the high intensity lamp 11 shown in Figure 3, shows an example of a metal halide lamp which can preferably be employed as a lamp for spot illumination such as in a display illumination or a projection-type liquid crystal TV set since a color rendition thereof is excellent. Inside a bulb glass 17 having the base 21, a quartz arc tube 18 is provided enclosed with mercury, argon and a metal halide. Light generation of metallic atoms decomposed in a mercury arc generated between electrodes 19 and 20 in the quartz arc tube 18, is utilized as a luminescence light source, which is radiated to the side of the face to be illuminated. Normally, the high intensity lamp 11 is often integrated with a reflecting plate (not shown) and a front glass (not shown) in front of a bulb, thereby enabling to concentratingly radiate in one direction.

In this specification, "cutting-off limit" is defined by a wavelength disposed at a median between two wavelengths having transmittances of 5% and 72%, and "width of cutting-off inclination" is defined by a difference between the wavelengths having the transmittances of 5% and 72%.

In the high intensity lamp 11 formed as above, the bulb glass 12 or 17 and/or the front glass 14 of a bulb, are formed by a glass material provided with an ultraviolet light ray cutting-off function having a cutting-off limit in a wavelength range of 350 through 430 nm and a width of cutting-off inclination of not more than 20 nm, that is, a glass material precipitated with microcrystals of CuC^ _χ Br ₁ _ _χ (x = 0 through 1.0). In case of employing the glass material precipitated with the microcrystals of CuC^ _χ Br ₁ _ _χ (x = 0 through 1.0), since crystal grains per se thereof are provided with light absorbing effect, the provided bulb glass 12 or 17 and/or the front glass 14 of a bulb can be provided with an extremely sharp cutting-off function wherein the width of cutting-off inclination is not more than 20 nm in the ultraviolet light ray range.

In this invention, when the cutting-off limit is under 350 nm, the cutting-off the ultraviolet light ray component is insufficient. On the other hand, when the cutting-off limit exceeds 430 nm, absorption of a visible light ray takes place and, therefore, undesirable

coloration is remarkably provided.

Furthermore, when the width of cutting-off inclination exceeds 20 nm, the absorption of the visible light ray takes place, or the cutting-off the ultraviolet light ray component is insufficient.

Furthermore, normally, the cutting-off limit of the glass precipitated with microcrystals is in a range of 350 through 380 nm for CuC^ and 400 through 430 nm for CuBr, respectively. However, the range of the cutting- off limit can be controlled to be long or short in the spectro range above mentioned, by controlling the grain size of the respective precipitated microcrystals.

Furthermore, since CuC^ and CuBr make a complete solid solution in all the composition range, the cutting- off limit can be controlled in a range of 380 through 430 nm by precipitating microcrystals of an arbitrary composition of CuC^Br^ _j . (x = 0 through 1.0).

Accordingly, by pertinently combining the above methods according to the requirements, the glass material having the cutting-off limit in a range of 350 through 430 nm can be formed.

Furthermore, the glass material which is employed for forming the above glass composing the present invention, can be employed without special limitation, so far as the microcrystals of CuC^Br-^ _j . (x = 0 through 1.0) are precipitated.

Furthermore, in forming the bulb glass 12 or 17

and/or the front glass 14 of a bulb having the ultraviolet light ray cutting-off function, a heat treatment is necessary after the glass material is molten and formed for precipitating the microcrystals. By controlling the grain size of the microcrystals precipitated under the heat treatment condition, the cutting-off limit and the width of cutting-off inclination can be controlled.

The heat treatment in this case can be performed, for instance, after the glass material is formed into the bulb glass 12 or 17 and/or the front glass 14 of a bulb and annealed. Or, the heat treatment can be performed simultaneously with the annealing operation in an on-line annealing step after the melting and the forming. In any way _r the method of making thereof can be performed by the publicly-known various steps of melting, forming, annealing and heat-treating without any restriction.

The bulb glass of this invention can be formed into a hollow spherical body having a pertinent shape covering a light source such as in the bulb glass 12 or 17 illustrated as above, or a tube-like body, or an outer bulb for covering the lamp per se. Furthermore, the front glass 14 of a bulb can be formed into a pertinent desired shape by pressing, such as a plane, a curved face, a lens-like shape or the like.

Since the high intensity lamp 11 of this invention is composed as above, the illuminating light which is

generated from the heat radiating light source having the filament 15 or the luminescence light source having the quartz arc tube 18 radiates and illuminates the side of the face to be illuminated, while effectively cutting-off the generated ultraviolet light ray component, by transmitting through the bulb glass 12 or 17 and/or the front glass 14 of a bulb provided with the ultraviolet light ray cutting-off function having the cutting-off limit in a range of 350 through 430 nm and the width of cutting-off inclination of not more than 20 nm.

Accordingly, since the member composed of a synthetic resin material or a textile material disposed on the side of the face to be illuminated, is radiated without receiving the ultraviolet light ray hazard such as color fading or quality deterioration, it is possible to enjoy an illuminating effect having a high illuminating light density, while the durability of the member per se is remarkably promoted.

Figure 4 shows a radiation intensity which is measured by employing the following method, to confirm the ultraviolet light ray cutting-off function employing the high intensity lamp of this invention.

A cylindrical body (bulb glass) having a thickness of 1 mm is formed by melting alkali borosilicate glass composed to contain CuC^ and CuBr by 1.0 wt%, respectively at 1450°C, forming it in a cylindrical shape and heat-treating it at 500°C for 1 hour.

The cylindrical body (bulb glass) provided as above is covered on a metal halide lamp on sale and a radiation intensity of light radiated by transmitting through the cylindrical body (bulb glass), is measured. In Figure 4, the bold line portion 2 of the distribution curve 1 between 300 nm and 400 nm, designates a radiation intensity in case of not covering the cylindrical body (bulb glass) on the metal halide lamp, and the dotted line 3, the radiation intensity in case of covering the cylindrical body (bulb glass) on the metal halide lamp.

According to Figure 4, it is confirmed that the bulb glass (cylindrical body) is provided with the ultraviolet light ray cutting-off function having the cutting-off limit of 390 nm and the width of cutting-off inclination of 10 nm. Therefore, it is clarified that the ultraviolet light ray component in the illuminating light generated by the light source can effectively be cut-off by employing the bulb glass of this invention. INDUSTRIAL APPLICABILITY

As stated above, according to the present invention, the illuminating light generated from the light source of the high intensity lamp illuminates the surface to be illuminated while the ultraviolet light ray component thereof is effectively cut-off by the bulb glass and/or the front glass of a bulb. Accordingly, the member disposed on the side of the face to be illuminated can be

protected from the ultraviolet light ray hazard such as color fading or quality deterioration, the durability thereof can be promoted and the bad influence on a human body can be prevented.