Patent Grant
9863602
This application claims the priority benefit under 35 U.S.C. §119 of Japanese Patent Application No. 2014-195170 filed on Sep. 25, 2014, which is hereby incorporated in its entirety by reference.
The presently disclosed subject matter relates to LED light source devices and lighting fixtures using the same, and in particular, to an LED light source device having an LED including an LED element as a light emission source and capable of possessing the same light distribution characteristics and luminance distribution as those of a common bulb having a coiled filament as a light emission source. The LED light source device is also capable of providing the same light distribution pattern when it is used for a lighting fixture that utilizes a bulb as a light source, in place of a bulb. Also, the presently disclosed subject matter relates to a lighting fixture using the LED light source device.
Japanese Patent No. 4689762 discloses an LED bulb as conventional LED light source devices of this type, which can include an optical system as illustrated in
The disclosed LED bulb can include an LED light emitting element 100 and a reflecting member 101 disposed forward of the LED light emitting element 100 in its light illumination direction. The reflecting member 101 can include a reflecting surface 105 facing to the light emission surface 102 of the LED light emitting element 100 and having a center axis 106. The reflecting surface 105 can be composed of an apex 103 projecting toward the light emission surface 102 of the LED light emitting element 100, and a curved conical reflecting surface 104 that is a side surface extending from the apex 103 and concavely curved toward the center axis 106.
With this configuration, the light emitted from the LED light emitting element 100 can be radially reflected sideward and obliquely rearward with respect to the light illumination direction by means of the curved conical reflecting surface 104 of the reflecting member 101. Then the curved conical reflecting surface 104 can form a pseud light source (E) by the reflected light (F) therefrom. According to the conventional light source device disclosed in the conventional art, the light emission direction of light from the pseud light source (E) can be substantially the same as the light emission direction of light from a halogen bulb with a filament. Consequently, the formed position and the size of the light emission region of the pseud light source (E) can be the same as those of such a halogen bulb.
In the LED bulb disclosed in Japanese Patent No. 4689762, the light from the pseud light source (E) can be reflected by the curved conical reflecting surface 104, so that the reflected light (D) can form the light distribution pattern 107 as illustrated in
In other words, the light distribution characteristics of the pseud light source (E) can correspond to those of a coiled filament (F) that is prepared by winding filament while gradually changing the winding diameter to form a curved conical shape. Therefore, the pseud light source (E) can emit light rays including first light rays emitted from first portions corresponding to those of filament wound with larger diameters and second light rays emitted from second portions corresponding to those of filament wound with smaller diameters. When such a pseud light source (E) is mounted within a lighting fixture having a light distribution control system, the first light rays from the first portions of the pseud light source (E) can be controlled in light distribution characteristics in such a manner that they are spread by the light distribution control system while the second light rays from the second portions thereof can be controlled in light distribution characteristics in such a manner that they are converged to a certain direction.
As a result, the lighting fixture with such a pseud light source (E) installed therein is difficult to obtain the same or similar light distribution characteristics and illuminance distribution as or to those of a conventional lighting fixture including a coiled filament with a constant diameter. In short, even if a bulb is replaced with such an LED bulb, the light distribution characteristics of such a lighting fixture are remarkably different from those of a lighting fixture with a conventional bulb.
Furthermore, the reflecting member 101 having the curved conical reflecting surface 104 that can provide such a pseud light source (E) needs to be supported by a columnar support, and such a columnar support must be arranged in the vicinity of the reflecting member 101 due to the limited space within the lighting fixture. This, however, results in formation of a shadow by the columnar support shielding the light emitted from the pseud light source (E).
The presently disclosed subject matter was devised in view of these and other problems and features in association with the conventional art. According to an aspect of the presently disclosed subject matter, an LED light source can employ an LED including an LED element as a light emission source and is capable of possessing the same or similar light distribution characteristics and luminance distribution as or to those of a common electric bulb having a coiled filament as a light emission source. The LED light source device is also capable of providing the same light distribution pattern when it is used for a lighting fixture that utilizes a bulb as a light source, in place of a bulb.
According to another aspect of the presently disclosed subject matter, an LED light source device can include: an LED including an LED element as a light emission source; and a light reflecting body configured to include a light reflecting surface configured to reflect light emitted from the LED in a predetermined direction. The light reflecting surface can include at least a first light reflecting surface composed of a first hyperbolic cylindrical surface. The first hyperbolic cylindrical surface can have an inner focal line inside the light reflecting body and be obtained by moving part of a hyperbolic line in a perpendicular direction to a plane including the hyperbolic line, the hyperbolic line having an outer focal point at or near a position at which the LED element is located.
According to another aspect of the presently disclosed subject matter, the LED light source device according to the above-described aspect can be configured such that the first light reflecting surface can further include a second hyperbolic cylindrical surface. The second hyperbolic cylindrical surface can have an inner focal line located at the inner focal line of the first hyperbolic cylindrical surface and be obtained by moving part of a hyperbolic line in a perpendicular direction to a plane including the hyperbolic line, the hyperbolic line having an outer focal point at a position different from the outer focal point of the hyperbolic line of the first hyperbolic cylindrical surface.
According to still another aspect of the presently disclosed subject matter, the LED light source device according to the above-described aspect can be configured such that the LED can comprise at least a first LED and a second LED, and the first LED can be located at or near an outer focal line obtained by moving the outer focal point of the hyperbolic line of the first hyperbolic cylindrical surface and the second LED can be located at or near an outer focal line obtained by moving the outer focal point of the hyperbolic line the second hyperbolic cylindrical surface.
According to still another aspect of the presently disclosed subject matter, the LED light source device according to any one of the above-described aspects can be configured such that the light reflecting surface can further include a second light reflecting surface. The second light reflecting surface can be configured by a free curved surface provided so as to protrude in a direction substantially perpendicular to an optical axis of the LED element and away from the LED farther than the first light reflecting surface. In this LED light source, light rays emitted from the LED element within a predetermined emission angular range around the optical axis can be incident on the first light reflecting surface and light rays emitted from the LED element by a larger angle than the predetermined emission angular range can be incident on the second light reflecting surface.
According to still another aspect of the presently disclosed subject matter, the LED light source device according to any one of the above-described aspects can be configured such that the LED can be produced by resin-sealing an LED element with a translucent resin so as to have an aspheric light emission surface. The light rays emitted from the LED element to enter the translucent resin can be refracted by the light emission surface of the translucent resin by means of lens effects to be bent toward the optical axis of the LED element when exiting the translucent resin.
Furthermore, according to still another aspect of the presently disclosed subject matter, a lighting fixture can include a reflector having a lighting chamber, an outer lens made of a transparent resin and configured to cover the reflector to define the lighting chamber, and the LED light source device according to any one of the above-described aspects, the LED light source device disposed in the lighting chamber.
As described above, the LED light source device of the presently disclosed subject matter can include the LED having the LED element as a light emission source and a light reflecting body configured to include the first and second light reflecting surfaces that are configured to reflect the light rays emitted from the LED element to predetermined directions. Further, the first light reflecting surface can be formed from a hyperbolic cylindrical surface with an outer focal line, at a certain point of which the LED can be located while the LED can be disposed to face the first light reflecting surface.
With the above-described configuration, the light rays emitted from the LED and incident on the first light reflecting surface can be reflected to an extending direction of a line connecting the incident point of the first light reflecting surface of the hyperbolic cylindrical surface and a point of an inner focal line of a hyperbolic line passing the incident point and the hyperbolic cylindrical surface. Accordingly, when the LED is assumed to be disposed above the light reflecting body and emit light rays downward, the reflected light rays can be irradiated toward a directional range of from sideward and obliquely upward direction to sideward and obliquely downward direction with respect to the first light reflecting surface, as if the reflected light rays are emitted from an apparent light source (pseud light source) disposed on a point of the inner focal line. This means that the light rays can be directed in substantially the same directions as the optical paths of light rays emitted from a coiled filament with a constant diameter (linearly extending coiled filament) and irradiated from an electric bulb toward a directional range of from sideward and obliquely upward direction to sideward and obliquely downward direction.
Therefore, the lighting fixture employing the LED light source device according to the presently disclosed subject matter can form substantially the same light distribution pattern as those obtained from a conventional lighting fixture employing an electric bulb as a light source. Therefore, even when the LED light source device of the presently disclosed subject matter is employed as a light source for a common lighting fixture in place of a common electric bulb, the same or similar light distribution characteristics and luminance distribution can be achieved without modifying the lighting fixture. Furthermore, such a common lighting fixture can employ the LED light source device simply by replacing the light source bulb of such a common lighting fixture with the LED light source device, whereby the service life of the lighting fixture can be prolonged.
These and other characteristics, features, and advantages of the presently disclosed subject matter will become clear from the following description with reference to the accompanying drawings, wherein:
A description will now be made below to LED light source devices of the presently disclosed subject matter with reference to the accompanying drawings,
In the description, the directions are based on the posture of a light source device in which an LED element is disposed above a light reflecting body and can emit light rays downward as illustrated in
The LED light source device 1 can mainly include, as illustrated in
The LED mounting board 10 can include a substrate 11 on which a plurality of (in the illustrated exemplary embodiment, two) LEDs, first and second LEDs 12 and 15, are mounted. As illustrated in
With reference to
The light reflecting body 30 can include a dome portion 40 horizontally long at its upper portion and a pair of flange portions 50 and 55 extending along the lower edge of the dome portion 40 and outward from opposite portions of the lower edge of the dome portion 40. The dome portion 40 can have a ridge portion 43 at its top and a dome-shaped outer peripheral surface while being vertically cut at both ends in the lengthwise direction across its width, and a groove (circuit board insertion groove) 41 configured to receive and fix the circuit board 25 by fitting can be formed from at least one end side of the dome portion 40.
The outer peripheral surface of the dome portion 40 can include a composite reflecting mirror surface (hereinafter, may be referred to simply as the “composite reflecting surface”) composed of a plurality of continuous reflecting mirror surfaces. In particular, as also illustrated in
Each of the pair of supporting main bodies 60 and 80 can include a heatsink portion 65, 85, a trunk portion 70, 90, and a semispherical-cup shaped base portion 75, 95. The heatsink portion 65, 85 can include a plurality of heat dissipation fins 61, 81 provided so as to radially extend, and a horizontally extending groove (LED mounting board insertion groove) 62, 82 thereinside so as to receive and support the LED mounting board 10. The trunk portions 70 and 90 extending from the corresponding heatsink portions 65 and 85 with a narrow width can hold the light reflecting body 30 and the circuit board 25 together. The semispherical-cup shaped base portion 75, 95 can be formed continuously from the corresponding trunk portion 70, 90 and have an insertion hole (circuit board insertion hole) 75a, 95a for receiving the circuit board 25 so that the one end of the circuit board 25 can extend outside of the semispherical-cup shaped base portion 75, 95. When assembling, the pair of supporting main bodies 60 and 80 can be united as a single unit while the LED mounting board 10, the circuit board 25, and the light reflecting body 30 are housed therein and supported thereby.
Furthermore, the supporting main body 60, 80 can include a semi-cylindrical coupling support 66, 86 provided so as to protrude upward at the heatsink portion 65, 85. When uniting the pair of supporting main bodies 60 and 80, while the semi-cylindrical coupling supports 66 and 86 are being mated with each other at their inner surfaces 66a and 86a, the cylindrical coupling ring 5 can surround the mated coupling supports 66 and 86. In this state, a cylinder shape can be completed by the coupling supports 66 and 86, and, as illustrated in
The LED mounting board 10 and the circuit board 25 can be electrically connected to each other by lead wires 6. In order to arrange the lead wires 6, the light reflecting body 30 can be provided with a lead wire insertion groove 42 extending upward from the circuit board insertion groove 41. The electrical connection between the LED mounting board 10 and the circuit board 25 is not limited by the lead wires, but may be achieved by employing a circuit board formed from a flexible substrate or rigid substrate.
As described above, the LED light source device 1 can be constituted by the coupling ring 5, the LED mounting board 10, the circuit board 25, the light reflecting body 30, the pair of supporting main bodies 60 and 80. After assembling them, the cylindrically combined coupling supports 66 and 86 protruded from the respective heatsink portions 65 and 85 of the supporting main bodies 60 and 80 can be clamped by the cylindrical coupling ring 5, and the formed space within the cylindrically combined coupling supports 66 and 86 can be filled with the adhesive 7. In this manner, the supporting main bodies 60 and 80 can be integrally formed while the heatsink portions 65 and 85 and the base portions 75 and 95 are in close contact with each other, and the LED mounting board 10, the circuit board 25, the light reflecting body 30 can be housed within the integrated supporting main bodies 60 and 80.
In this configuration, the LED mounting board 10 can be inserted into and fit to the LED mounting board insertion grooves 62 and 82 of the heatsink portions 65 and 85, and the circuit board 25 can be inserted into and fit to the circuit board insertion groove 41 provided to the dome portion 40 of the light reflecting body 30.
In addition to this, the circuit board 25 can be interposed and held by the trunk portions 70 and 90 of the respective supporting main bodies 60 and 80, and the light reflecting body 30 can be interposed and held by the trunk portions 70 and 90 at its dome portion 40 and by the base portions 75 and 95 at its flange portions 50 and 55.
The LEDs 12 and 15 can be mounted on the lower surface of the LED mounting board 10 so that the irradiation direction thereof is directed toward the dome portion 40 of the light reflecting body 30, and can be electrically coupled with the circuit board 25 by the lead wires 6. Furthermore, the circuit board 10 at its one end can be inserted into and pass through the circuit board insertion holes 75a and 95a provided to the respective base portions 75 and 95 of the supporting main bodies 60 and 80.
A description will now be given of the optical system of the LED light source device with the above-described configuration with reference to the partial enlarged cross-sectional view of
The pair of first light reflecting surfaces 44 and 45 of the dome portion 40 in the light reflecting body 30 can each be formed from a hyperbolic cylindrical surface extending in the lengthwise direction and showing a cross section 44a, 45a in the width direction being a certain hyperbolic surface. The hyperbolic cylindrical surfaces of the first light reflecting surfaces 44 and 45 can have a common inner focal line f1.
Furthermore, the first LED 12 can be disposed to face the hyperbolic cylindrical surface of the first light reflecting surface 44 having the inner focal line f1, so that the LED element 13 is positioned near or at a position which is a focal point f2a of a hyperbolic line 44a′ that is paired with the hyperbolic line 44a (with the focal point f2a being located on an outer focal line paired with the inner focal line f1). In the same manner, the second LED 15 can be disposed to face the hyperbolic cylindrical surface of the first light reflecting surface 45 having the inner focal line f1, so that the LED element 16 is positioned near or at a position which is a focal point f2b of a hyperbolic line 45a′ that is paired with the hyperbolic line 45a (with the focal point f2b being located on an outer focal line paired with the inner focal line f1).
With this configuration, out of light rays emitted from the LED element 13 of the first LED 12 and exiting through the light emission surface 14a via the sealing resin 14, light rays L1a directed within a predetermined emission angular range about the optical axis Xa of the LED element 13 can be incident on the first light reflecting surface 44 formed from the hyperbolic cylindrical surface having the focal line f1.
The light rays L1a incident on the first light reflecting surface 44 can be reflected to an extending direction of a line connecting the incident point P of the first light reflecting surface 44 and a point of the inner focal line f1. Specifically, the light rays L1a emitted from the light emission source at the position of focal point f2a and reflected by the first light reflecting surface 44 can be irradiated toward a directional range of from sideward and obliquely upward direction to sideward and obliquely downward direction with respect to the first light reflecting surface 44, as if the reflected light rays L1a are emitted from an apparent light source (pseud light source) disposed on a point of the inner focal line f1.
In the same manner, out of light rays emitted from the LED element 16 of the second LED 15 and exiting through the light emission surface 17a via the sealing resin 17, light rays L2a directed within a predetermined emission angular range about the optical axis Xb of the LED element 16 can be incident on the first light reflecting surface 45 formed from the hyperbolic cylindrical surface having the focal line f1.
The light rays L2a incident on the first light reflecting surface 45 can be reflected to an extending direction of a line connecting the incident point Q of the first light reflecting surface 45 and a point of the inner focal line f1. Specifically, the light rays L2a emitted from the light emission source at the position of focal point f2b and reflected by the first light reflecting surface 45 can be irradiated toward a directional range of from sideward and obliquely upward direction to sideward and obliquely downward direction with respect to the first light reflecting surface 45, as if the reflected light rays L2a are emitted from an apparent light source (pseud light source) disposed on a point of the inner focal line f1.
Furthermore, out of light rays emitted from the LED element 13 of the first LED 12 and exiting through the light emission surface 14a via the sealing resin 14, light rays L1b directed by a larger angle (larger angular range) than the predetermined emission angular range about the optical axis Xa of the LED element 13 can be incident on the second light reflecting surface 51 of the flange portion 50. Then, the light rays L1b incident on the second light reflecting surface 51 can be reflected to an obliquely upward direction with respect to the second light reflecting surface 51.
In the same manner, out of light rays emitted from the LED element 16 of the second LED 15 and exiting through the light emission surface 17a via the sealing resin 17, light rays L2b directed by a larger angle (larger angular range) than the predetermined emission angular range about the optical axis Xb of the LED element 16 can be incident on the second light reflecting surface 56 of the flange portion 55. Then, the light rays L2b incident on the second light reflecting surface 56 can be reflected to an obliquely upward direction with respect to the second light reflecting surface 56.
It should be noted that the light rays L1a reflected by the first light reflecting surface 44 and directed toward a directional range of from sideward and obliquely upward direction to sideward and obliquely downward direction with respect to the first light reflecting surface 44 and the light rays L1b reflected by the second light reflecting surface 51 and directed to an obliquely upward direction with respect to the second light reflecting surface 51 can be irradiated outward through an opening 97 formed by the integrated supporting main bodies 60 and 80. (See
Therefore, the light rays reflected by the first light reflecting surfaces 44 and 45 and the second light reflecting surfaces 51 and 56 can be irradiated outside of the LED light source device without being shielded, which can increase the light utilization efficiency as well as achieve the brighter LED light source device 1.
Then, the light emission direction of the exiting light rays from the LED light source device with the above configuration will be compared with the light emission direction of the exiting light rays from the linearly extended coiled filament 150.
Next, further comparison will be made between a conventional lighting fixture, as illustrated in
Furthermore, the optical paths of the light rays L10b emitted from the filament 150 and irradiated from the electric bulb 151 to be directed to obliquely upward directions with respect to the electric bulb 151 can be substantially the same as those of the light rays L20b emitted from the apparent pseud light source at the position of focal line f1 and irradiated from the LED light source device 1 to be directed to obliquely upward directions with respect to the LED light source device 1 due to the second light reflecting surfaces 51 and 56.
With this conventional lighting fixture 154 utilizing the electric bulb 151 as a light source, the light rays L10a irradiated to be directed toward the directional range of from sideward and obliquely upward direction to sideward and obliquely downward direction with respect to the electric bulb 151 and reflected by a light reflecting surface 152 of a reflector 153 and passing through a forward outer lens 155 and the light rays L10b irradiated to be directed to the obliquely upward directions with respect to the electric bulb 151 and directly passing through the outer lens 155 can be combined to form a light distribution pattern. On the other hand, with the lighting fixture 200 utilizing the LED light source device 1 as a light source, the light rays L20a irradiated to be directed toward the directional range of from sideward and obliquely upward direction to sideward and obliquely downward direction with respect to the LED light source device 1 and reflected by a light reflecting surface 152 of a reflector 153 and passing through a forward outer lens 155 and the light rays L20b irradiated to be directed to obliquely upward directions with respect to the LED light source device 1 and directly passing through the outer lens 155 can be combined to form a light distribution pattern. The resulting light distribution pattern formed by the lighting fixture 200 utilizing the LED light source device 1 can be almost the same as that formed by the conventional lighting fixture 154 utilizing the electric bulb 151 (filament 150).
Therefore, even when the LED light source device 1 of the presently disclosed subject matter is employed as a light source for a common lighting fixture in place of a common electric bulb, the same or similar light distribution characteristics and luminance distribution can be achieved without modifying the lighting fixture. Furthermore, such a common lighting fixture can employ the LED light source device simply by replacing the electric bulb of such a common lighting fixture with the LED light source device, whereby the service life of the lighting fixture can be prolonged.
Next, a description will be give of a comparison of the LED light source device of the presently disclosed subject matter (first exemplary embodiment) with a conventional LED bulb as disclosed in Japanese Patent No. 4689762.
As disclosed therein, the conventional LED bulb can provide an elongated oval shape as a pseud light source shape due to the curved conical reflecting surface of the reflecting member, which serves as a pseud light source by the reflected light therefrom, and thus, the shape of the pseud light source of the conventional LED bulb is absolutely different from the common filament shape (linearly extending with a constant diameter) as a light source for a common electric bulb. As a result, even if an electric bulb of a lighting fixture is replaced with the conventional LED bulb, since the light distribution pattern provided by the lighting fixture using the conventional LED bulb is different from the original one, the simple replacement cannot achieve the normal use of such a lighting fixture with the different light distribution pattern.
Furthermore, in the lighting fixture using such a conventional LED bulb, almost all the light rays emitted from the LED light emitting element are irradiated outside of the lighting fixture via two times reflection by the reflecting surface of the reflecting member and a concave reflecting mirror of the lighting fixture. This results in failure of reproduction of direct light rays from a bulb. In view of this point, the lighting fixture with the conventional LED bulb replacing the electric bulb cannot reproduce the same light distribution pattern.
On the contrary, the LED light source device of the presently disclosed subject matter can provide almost the same shape as the common filament shape (linearly extending with a constant diameter) because the shape of the pseud light source by the reflected light from the LED light source can be formed by the first light reflecting surface with a hyperbolic cylindrical surface having an extended focal line, and the pseud light source can be shaped corresponding to the shape extending along the focal line. Consequently, even when the LED light source device of the presently disclosed subject matter is employed as a light source for a common lighting fixture in place of a common electric bulb, the same or similar light distribution pattern can be formed without modifying the lighting fixture.
In addition to this feature, in the lighting fixture utilizing the LED light source device of the presently disclosed subject matter, part of the light rays emitted from the LED light source can be reflected by the second light reflecting surfaces of the light reflecting body to obliquely upward directions and irradiated outward directly. Thus, the LED light source device with this configuration can achieve the reproduction of direct light rays from a bulb. In view of this point, the LED light source device can contribute to the formation of the light distribution pattern by the lighting fixture even when a bulb is replaced with the LED light source device.
Furthermore, in the LED light source device 1, the first LED 12 can irradiate the first light reflecting surface 44 and the second light reflecting surface 51 of the light reflecting body 30 with the emission light rays therefrom while the second LED 15 can irradiate the first light reflecting surface 45 and the second light reflecting surface 56 of the light reflecting body 30 with the emission light rays therefrom. This configuration can increase the amount of light rays reflected by the respective light reflecting surfaces 44, 51, 45, and 56, thereby achieving a brighter lighting fixture.
Next,
The second exemplary embodiment is different from the first exemplary embodiment in that the configuration of the first light reflecting surface of the light reflecting body and the positional relationship between the LED and the first light reflecting surface.
Specifically, the composite reflecting surface can include the first light reflecting surface 46 that can be formed from a hyperbolic cylindrical surface including the ridge portion 43 while being disposed at the center of the light reflecting body in the lengthwise direction when viewed from above. The hyperbolic cylindrical surface can extend in the lengthwise direction and show a cross section 46a in the width direction being a certain hyperbolic line.
Furthermore, an LED 18 can be disposed to face the hyperbolic cylindrical surface of the first light reflecting surface 46 having the inner focal line f1, with an LED element 19 positioned near or at a position which is a focal point f2 of a hyperbolic line 46a′ that is paired with the hyperbolic line 46a (with the focal point f2 being located on an outer focal line paired with the inner focal line f1).
With this configuration, out of light rays emitted from the LED element 19 of the LED 18 and exiting through the light emission surface 20a via the sealing resin 20, light rays L5a directed within a predetermined emission angular range about and including the optical axis X of the LED element 19 can be incident on the first light reflecting surface 46 formed from the hyperbolic cylindrical surface having the focal line f1.
The light rays L5a incident on the first light reflecting surface 46 can be reflected by the same to an extending direction of a line connecting the incident point R of the first light reflecting surface 46 and the closest point of the inner focal line f1 to the incident point R. Specifically, the light rays L5a emitted from the light emission source at the position of focal point f2 and reflected by the first light reflecting surface 46 can be irradiated toward a directional range of from sideward and obliquely upward direction to sideward and obliquely downward direction with respect to the first light reflecting surface 46, as if the reflected light rays L5a are emitted from an apparent light source (pseud light source) disposed on a point of the inner focal line f1.
Furthermore, out of light rays emitted from the LED element 19 of the LED 18 and exiting through the light emission surface 20a via the sealing resin 20, light rays L5b directed by a larger angle (larger angular ranges with the optical axis X interposed therebetween) than the predetermined emission angular range about and including the optical axis X of the LED element 19 can be incident on the second light reflecting surfaces 51 and 56 of the flange portions 50 and 55. Then, the light rays L5b incident on the second light reflecting surfaces 51 and 56 can be reflected to obliquely upward directions with respect to the second light reflecting surfaces 51 and 56.
With this configuration, as in the first exemplary embodiment, the optical paths of light rays in the conventional lighting fixture are substantially the same as the optical paths of light rays in the lighting fixture utilizing the LED light source device. In the conventional lighting fixture, the light rays can be emitted from the filament (linearly extended coiled filament with a constant diameter) and irradiated from the electric bulb to be directed toward a directional range of from sideward and obliquely upward direction to sideward and obliquely downward direction with respect to the electric bulb. In the lighting fixture using the LED light source device of the presently disclosed subject matter, the light rays can be emitted from the apparent pseud light source disposed at a certain point on the focal line f1 and irradiated from the LED light source device to be directed toward the same or similar directional range as the conventional electric bulb (of from sideward and obliquely upward direction to sideward and obliquely downward direction with respect to the LED light source device).
Therefore, the resulting light distribution pattern formed by the lighting fixture utilizing the LED light source device according to the second exemplary embodiment can be almost the same as that formed by the conventional lighting fixture utilizing the electric bulb (filament). Therefore, even when the LED light source device of the presently disclosed subject matter is employed as a light source for a common lighting fixture in place of a common electric bulb, the same or similar light distribution characteristics and luminance distribution can be achieved without modifying the lighting fixture. Furthermore, such a common lighting fixture can employ the LED light source device simply by replacing the electric bulb of such a common lighting fixture with the LED light source device, whereby the service life of the lighting fixture can be prolonged.
Note that in the second exemplary embodiment, a single LED 18 can irradiate with light rays the first light reflecting surface 46 disposed on both sides in the width direction with the ridge portion 43 interposed therebetween. This configuration can reduce the number of used LED elements, thereby achieving cost reduction in manufacture of the LED light source device as well as parts cost.
It will be apparent to those skilled in the art that various modifications and variations can be made in the presently disclosed subject matter without departing from the spirit or scope of the presently disclosed subject matter. Thus, it is intended that the presently disclosed subject matter cover the modifications and variations of the presently disclosed subject matter provided they come within the scope of the appended claims and their equivalents. All related art references described above are hereby incorporated in their entirety by reference.
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