The present invention relates to an incandescent type electric lamp including a halogen lamp, etc., and more particularly, to an electric lamp used as a light source of an optical fiber lighting system.
Conventionally, an optical fiber lighting system is widely used for lighting to illuminate areas near the hands of workers who perform elaborate work, for example, at a factory, and decorative lighting of a show case or show window on one hand, and for irradiation necessary for an endoscope, scanner, photoenlarger, photopolymerizer, etc., on the other.
For the optical fiber 200, a quartz-based optical fiber, multi-component optical fiber or plastic optical fiber, etc., may be used. In the figure, only one optical fiber is shown, but several to several tens of thousands of fibers are normally used as tied in a bundle. Furthermore, the optical fiber 200 has a numerical aperture NA which indicates an angle at which it can receive a light on its end face. According to the numerical aperture NA of the optical fiber 200 used and a curvature of the reflective portion 105 of the reflector 102 of the halogen lamp 100, the halogen lamp 100 and optical fiber 200 are positioned at an appropriate distance X from each other. In this case, the halogen lamp 100 and optical fiber 200 are concentrically positioned so that the axis of the (bundled) optical fiber 200 coincides with the optical axis of the reflective portion 105 of the reflector 102(see single-dot dashed line in the figure).
In the optical fiber lighting system in
As is evident from the light distribution in
Furthermore, when the halogen lamp 100 shown in the figure is used, a mold for molding the glass reflector 102 is very expensive, and it is therefore difficult to provide many types of ellipsoidal reflective portions 105 of the reflector 102 with different curvatures and providing them involves an enormous cost. It is an actual situation that only a few types of reflector can be provided and they are adapted by adapting the size, form, etc., of the bulb according to the application or displacing the bulb inside the reflector according to the application. However, with such adaptations, it is difficult to obtain a desired light distribution characteristic and may be even impossible to do so.
Furthermore, when the halogen lamp 100 in the figure is used, the reflector 102 as a part independent of the bulb is required, which results in a problem that it is difficult to reduce the size of the optical fiber lighting system.
Note that an optical fiber lighting system using an incandescent electric lamp as a light source is known in German Utility Model No.DE-7904647 U. This optical fiber lighting system is provided with a reflective layer on the bulb of the incandescent electric lamp. This optical fiber lighting system also has a characteristic that luminous intensity near the central area in a light distribution of the light emerged from the optical fiber drops compared to the luminous intensity on the periphery.
It is an object of the present invention to provide an incandescent type electric lamp, a halogen lamp in particular, which is suitable as a light source for an optical fiber lighting system, which can be manufactured at a low cost and which is small.
In order to attain this object, the electric lamp according to the present invention is characterized by comprising a bulb comprising a first curved face, the first curved face having a substantially ellipsoidal shape in cross section with a first focal point and a second focal point, and being convex outwardly, and, a filament comprising a coil part formed by winding a wire and generating a light by being energized, the filament being so arranged that the coil part is positioned in an inner space of the bulb, wherein a reflective coating is formed on the whole of outer surface or the whole of inner surface of the first curved face, and the first curved face is so adapted that the first focal point is positioned at the coil part, and the second focal point is positioned at a light transmission medium to which an emerged light generated at the coil part and reflected on the first curved face is provided.
According to the electric lamp in the above-described structure, the first curved face having a substantially ellipsoidal shape in cross section is made in the bulb itself of the electric lamp and the reflective coating is formed on the whole of outer surface or the whole of inner surface of the first curved face, and therefore it is possible to manufacture the electric lamp at a low cost and reduce the size of the electric lamp considerably. Furthermore, in the light transmission medium lighting system using the electric lamp in the above-described structure as a light source, emerged light of the light transmission medium such as an optical fiber can have a light distribution characteristic having a peak in the vicinity of the center. A light having such a light distribution characteristic is quite suitable for an application of optical fiber lighting.
Preferably, in the above-described electric lamp, a second face, facing the first curved face, includes a substantially spherical shape and the bulb further comprises a circumferential face for interconnecting a circumferential end portion of the first curved face and a circumferential end portion of the second face.
According to the electric lamp in the above-described structure, it is advantageous because the thickness of the bulb of the electric lamp is substantially fixed in the portion of the inner space of the bulb. Equalizing the thickness of the glass is advantageous in preventing bursting of the bulb.
Preferably, in the above-described electric lamp, the second face includes a flat portion and preferably, the flat portion has a circular shape, and has at least a size of passing almost all of emerged light generated at the coil part at the first focal point and reflected on the first curved face.
According to the electric lamp in the above-described structure, it is advantageous in that it is possible to easily position the electric lamp and light transmission medium by letting the flat portion contact a flat reference surface provided in the light transmission medium lighting system. It is also advantageous in that that the emerged light that passes through the flat portion refracts only at a small degree at the flat portion. It is further advantageous in that it is possible to accurately visually confirm the position of the filament through the flat portion.
Preferably, in the above-described electric lamp, the second face comprises a protrusion portion, which protrudes toward the light transmission medium.
According to the electric lamp in the above-described structure, it is advantageous in that the electric lamp and light transmission medium can be positioned extremely easily by inserting the protrusion portion in the hole of the reference surface provided in the light transmission medium lighting system.
Preferably, in the above-described electric lamp, the second face has a coating for reflecting, transmitting or absorbing a light of a particular wavelength.
According to the electric lamp in the above-described structure, it is advantageous in the aspects of cost and miniaturization of the light transmission medium lighting system, because there is no need to separately provide a filter having characteristics such as infrared cutting.
Furthermore, the electric lamp according to the present invention is characterized by comprising a bulb comprising a first curved face, the first curved face having a substantially ellipsoidal shape in cross section with a first focal point and a second focal point, and being convex outwardly, and a second curved face, facing the first curved face, the second curved face having a substantially ellipsoidal shape in cross section with a first focal point and a second focal point, and being convex outwardly, and a filament comprising a coil part formed by winding a wire and generating a light by being energized, the filament being so arranged that the coil part is positioned in an inner space of the bulb, wherein the respective reflective coatings are formed on the first curved face and the second curved face, wherein the reflective coating comprises an opening for passing an emerged light generated at the coil part and reflected on the first curved face or the second curved face, the first curved face is so adapted that the first focal point is positioned at the coil part, and the second focal point is positioned at a light transmission medium to which an emerged light generated at the coil part and reflected on the first curved face is provided through the opening, and the second curved face is so adapted that the first focal point is positioned at the coil part, and the second focal point is positioned at a light transmission medium to which an emerged light generated at the coil part and reflected on the second curved face is provided through the opening. Preferably, the first and second curved faces have the same curvature. Furthermore, preferably, at least one of the openings has a circular shape, and has at least a size of passing almost all of emerged light generated at the coil part at the first focal point of the first curved face or the second curved face and reflected on the first curved face or the second curved face.
According to the electric lamp in the above-described structure, the first and second curved faces having a substantially ellipsoidal shape in cross section are made in the bulb itself of the electric lamp and a reflective coating is formed on the first and second curved faces, and therefore it is possible to manufacture the electric lamp at a low cost and reduce the size of the electric lamp considerably. Furthermore, the light transmission medium lighting system using the electric lamp in the above-described structure as a light source allows light to enter light transmission media such as two optical fibers by this one electric lamp and allows emerged lights from these light transmission media to have a light distribution characteristic having a peak in the vicinity of the center. Such a light distribution characteristic is quite suitable for applications of optical fiber lighting.
Preferably, in the above-described electric lamp, at least one of the openings includes a flat portion.
According to the electric lamp in the above-described structure, it is advantageous in that it is possible to easily position the electric lamp and light transmission medium by letting the flat portion contact the flat reference surface provided in the light transmission medium lighting system. It is also advantageous that the emerged light which passes through the flat portion refracts only at a small degree at that flat portion. It is further advantageous in that it is possible to visually accurately confirm the position of the filament through the flat portion.
Preferably, in the above-described electric lamp, at least one of the openings comprises a protrusion portion, which protrudes toward the light transmission medium.
According to the electric lamp in the above-described structure, it is advantageous in that it is possible to position the electric lamp and light transmission medium extremely easily by inserting the protrusion portion in the hole of the reference surface provided in the light transmission medium lighting system.
Preferably, in the above-described electric lamp, an end face of the protrusion portion has a lens effect.
According to the electric lamp in the above-described structure, it is advantageous in that it is possible to condense, diffuse or collimate a light in a desired direction.
Preferably, in the above-described electric lamp, a reflective coating is formed on a side face of the protrusion portion.
According to the electric lamp in the above-described structure, it is advantageous in that the light does not escape from the side face of the protrusion portion.
Preferably, in the above-described electric lamp, the coil part has a square shape or a circular shape as viewed from the light transmission medium side.
According to the above-described electric lamp in the above-described structure, it is advantageous in that it is possible to prevent the light generated at the coil part of the filament and reflected on the first or second curved face from being intercepted by the filament.
Preferably, in the above-described electric lamp, the bulb comprises a circumferential face for interconnecting a circumferential end portion of the first curved face and a circumferential end portion of the second curved face.
According to the electric lamp in the above-described structure, it is advantageous in that the thickness of the bulb of the electric lamp can be substantially fixed in the portion of the inner space of the bulb. Equalizing the thickness of the glass is also advantageous in preventing bursting of the bulb.
Preferably, in the above-described electric lamp, the material of the reflective coating is Ta2O5/SiO2.Ta205/SiO2 is excellent in the aspects of heat resistance and exfoliation resistance.
Preferably, in the above-described electric lamp, the first curved face and/or the second curved face consist of plural portions with different curvatures.
According to the electric lamp in the above-described structure, it is advantageous in that it is possible to condense light on different second focal points on a light transmission medium such as an optical fiber.
Preferably, in the above-described electric lamp, halogen is filled in the inner space of the bulb.
Furthermore, according to the present invention, a light transmission medium lighting system, or an optical fiber lighting system in particular, is characterized by comprising an electric lamp and a light transmission medium, the electric lamp comprising a bulb comprising a first curved face, the first curved face having a substantially ellipsoidal shape in cross section with a first focal point and a second focal point, and being convex outwardly, and a second face, facing the first curved face, and a filament comprising a coil part formed by winding a wire and generating a light by being energized, the filament being so arranged that the coil part is positioned in an inner space of the bulb, and the light transmission medium being arranged in the vicinity of the second face, to which an emerged light generated at the coil part and reflected on the first curved face is provided, wherein a reflective coating is formed on the whole of outer surface or the whole of inner surface of the first curved face, and the first curved face is so adapted that the first focal point is positioned at the coil part, and the second focal point is positioned at the light transmission medium.
Furthermore, according to the present invention, a light transmission medium lighting system, or an optical fiber lighting system in particular, is characterized by comprising an electric lamp and two light transmission media, the electric lamp comprising a bulb comprising a first curved face, the first curved face having a substantially ellipsoidal shape in cross section with a first focal point and a second focal point, and being convex outwardly, and a second curved face, facing the first curved face, the second curved face having a substantially ellipsoidal shape in cross section with a first focal point and a second focal point, and being convex outwardly, and a filament comprising a coil part formed by winding a wire and generating a light by being energized, the filament being so arranged that the coil part is positioned in an inner space of the bulb, and the two light transmission media being arranged in the vicinity of the first curved face and the second curved face, respectively, to which an emerged light generated at the coil part and reflected on the first curved face or the second curved face is provided, wherein the respective reflective coatings are formed on the first curved face and the second curved face, the reflective coating comprises an opening for passing an emerged light generated at the coil part and reflected on the first curved face or the second curved face, the first curved face is so adapted that the first focal point is positioned at the coil part, and the second focal point is positioned at one light transmission medium to which an emerged light reflected on the first curved face is provided through the opening, and the second curved face is so adapted that the first focal point is positioned at the coil part, and the second focal point is positioned at the other light transmission medium to which an emerged light reflected on the second curved face is provided through the opening.
With reference now to the attached drawings, embodiments of the present invention will be explained in detail below.
In this embodiment, the bulb 2 has a substantially ellipsoidal shape in cross section with a first focal point F1 and a second focal point F2 and has an outwardly convex first curved face 10. A reflective coating (diagonally shaded area in
In this embodiment, the bulb 2 has a substantially spherical second face 11, facing the first curved face 10. Furthermore, the bulb 2 comprises a circumferential face 12 for interconnecting a circumferential end portion of the first curved face 10 and a circumferential end portion of the second face 11. The circumferential face 12 and seal 3 are interconnected through a transition portion 13. Providing the spherical second face 11 and circumferential face 12 is advantageous for substantially fixing the thickness of the bulb 2 of the electric lamp 1 in the portion of the inner space 5. The reason for this will be explained with reference to a manufacturing step of the lamp of this embodiment.
Manufacturing of the electric lamp of this embodiment is basically the same as that of the conventional halogen lamp. Furthermore, the method of molding the bulb is also the same as the conventional manufacturing method. The first curved face 10 having a substantially ellipsoidal shape in cross section, the substantially spherical second face 11 and the circumferential face 12 of the bulb 2 are molded by heating a predetermined portion of a glass tube having a predetermined tube diameter first, then surrounding the heated portion with a mold, blowing air into the tube and inflating the heated portion. In that case, a similar wind pressure is applied to portions equidistant from the axis of the glass tube, and therefore the thickness of glass after molding becomes uniform. In this embodiment, in the case of the above-described inflation, the distances from a point on the axis of the glass tube to the second face 11 and circumferential face 12 and part of the first curved face 10 are generally equal, and therefore the thickness of the glass after molding becomes equal. Equalizing the thickness of the glass is advantageous in preventing bursting of the bulb.
Furthermore, when the above-described bulb 2 is molded, the portion corresponding to the seal 3 and transition portion are also molded. The glass tube thus molded is shown in
On the other hand, the filament 6 provided with the coil part 16, inner leads 7a, 7b, outer leads 8a, 8b and Mo foils 9a, 9b are electrically welded, whereby a filament structure shown in
Then, a reflective coating is formed on the whole of outer surface of the first curved face 10 by means of vapor deposition such as CVD and the electric lamp is completed (see
Note that it is preferable to narrow the above-described transition portion 13 (especially see
Furthermore, according to the above-described manufacturing method, the first curved face 10, second face 11 and circumferential face 12, portion corresponding to the seal 3 and transition portion are molded from one glass tube, but these components may also be molded from different glass tubes and then united.
In the above-described explanation, the first curved face 10, second face 11 and circumferential face 12 are treated as different components, but the present invention may also be adapted so that a circumferential face is included in the first and/or second curved face and is formed when the first curved face and second face are contacted so as to form an inner space.
In contrast to the conventional halogen lamp, according to the electric lamp of this embodiment, the reflective coating is directly formed on the outer surface of the bulb, and therefore the material of the reflective coating is required to have heat resistance.
Furthermore, since it is expected that the electric lamp is frequently touched by human hands during the manufacturing work, a high degree of peeling resistance is also required. With all these points taken into consideration, in this embodiment, Ta2O5/SiO2 which is excellent in the aspects of heat resistance and strength is used as the material for the reflective coating. However, it is also possible to use materials such as aluminum, gold, ZnS/MgF2, ZnS/SiO2, TiO2/SiO2as required.
In this embodiment, the filament 6 provided with the coil part 16 is of a so-called transverse CF-6 type, has a square shape as viewed from the optical fiber 20 side and is placed in the inner space 5 of the bulb 2 such that the optical axis of the first curved face 10 passes through the center of the square shape. Furthermore, the first focal point F1 of the first curved face 10 is positioned in the center of the coil part 16 of the filament 6. This is advantageous in that the emerged light generated at the coil part 16 of the filament 6 and reflected on the first curved face 10 is prevented from being intercepted by the filament 6. However, in this respect, it is preferable for this embodiment that the filament 6 is of a CF-6 type, has a circular shape as viewed from the optical fiber 20 side and placed in the inner space 5 of the bulb 2 such that the optical axis of the first curved face 10 passes through the center of the circular part.
However, it is also possible to adopt a rectangular shape as viewed from the optical fiber 20 side and also use a filament of a C-6 type, CF-8 type, etc., as required.
Then, an experiment was conducted in the same optical fiber lighting system to compare quantities of light emerged from the optical fiber when a conventional halogen lamp provided with a separate reflector and the electric lamp according to the present invention are respectively lit at the same voltage (5 V). As a result, it has been confirmed that an increase of light quantity of approximately 32% is obtained using the electric lamp of the present invention.
Furthermore, compared to the cost for molding the conventional separate reflector, the cost for molding the bulb 2 is extremely cheep.
Moreover, the electric lamp of the present invention is very small in size because it includes no separate reflector. Furthermore, the ellipsoidal shaped portion of the bulb of the electric lamp of the present invention is small and can have an extremely short focus. Compared to the conventional electric lamp, this allows the electric lamp of the present invention to be brought closer to the optical fiber. Therefore, in the conventional optical fiber lighting system using the conventional electric lamp with a separate reflector as a light source, the space required for the conventional electric lamp is enough for the electric lamp according to the present invention. Therefore, it is possible to adapt the electric lamp according to the present invention to the conventional optical fiber lighting system by only changing the mounting structure of the electric lamp. On the other hand, when a new optical fiber lighting system is manufactured, the size of such a system can be made smaller than the conventional optical fiber lighting system.
Among conventional optical fiber lighting systems, one with a separate infrared cut filter, etc., interposed between the electric lamp and optical fiber is known. It is possible to omit such a separate filter by forming a coating having an infrared cut filter characteristic on the second face 11 of the electric lamp in
According to this embodiment, the reflective coating formed on the outer surface of the first curved face 52 has a first opening 54. The first opening 54 has a circular shape and has a size of passing almost all of emerged light generated at the coil part 16 of the filament 6 at the first focal point F1 of the second curved face 53 and reflected on the second curved face 53. Also, the reflective coating formed on the outer surface of the second curved face 53 has a second opening 55. The second opening 55 also has a circular shape and has a size of passing almost all of emerged light generated at the coil part 16 of the filament 6 at the first focal point F1 of the first curved face 52 and reflected on the first curved face 52. In the area of the first opening 54, the first curved face 52 has a first flat portion and in the area of the second opening 55, the second curved face 53 has a second flat portion. These flat portions have the same works and effects as those described in the embodiment in
Furthermore, the bulb 52 comprises a circumferential face 56 for interconnecting a circumferential end portion of the first curved face 52 and a circumferential end portion of the second curved face 53. As described above, providing the circumferential face 56 is advantageous for substantially fixing the thickness of the bulb 51 of the electric lamp 50 in the area of the inner space 57. Furthermore, providing the circumferential face 56 is advantageous in that when designing the bulb 51, by adapting, in dependence of the numerical aperture NA of the optical fiber used, not only the curvatures of the first curved face 52 and second curved face 53, but also the size in the width direction of the circumferential face 56 in association therewith, it is possible to make the area of the reflective surface of the bulb 51 as large as possible and make the first opening 54 and second opening 55 as small as possible. Note that no reflective coating is formed on the outer surface of the circumferential face 56. This is because the portion of the coil part 16 surrounded by the circumferential face 56 does not produce so a large light quantity. However, if desired, it is also possible to form a reflective coating, infrared cut filter or coating of other nature on the circumferential face 56.
In the optical fiber lighting system using the electric lamp 50 in this embodiment as a light source, two optical fibers are placed facing each other on both sides of the electric lamp 50 and the electric lamp 50 and these optical fibers are positioned as described in
In the embodiments explained with reference to
The present invention can be used as a light source for an optical fiber lighting system used for irradiation of light necessary for lighting to illuminate areas near the hands of workers who perform elaborate work, for example, at a factory, decorative illumination of a show case or show window, and for irradiation necessary for an endoscope, scanner, photoenlarger, photopolymerizer, etc.
Number | Date | Country | Kind |
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PCT/IB03/03335 | Jul 2003 | WO | international |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/IB04/51288 | 7/26/2004 | WO | 1/25/2006 |