This application claims the priority benefit under 35 U.S.C. §119 of Japanese Patent Application No. 2008-003877 filed on Jan. 11, 2008, which is hereby incorporated in its entirety by reference.
1. Technical Field
The presently disclosed subject matter relates to lighting devices, and in particular, to lighting devices which include a substrate provided with a light source and a lens with a lens cut portion formed on a rear surface thereof, the lens cut portion being configured to control the illumination direction of the device.
2. Description of the Related Art
Known conventional lighting devices have a substrate, a lens (lens portion), and a light source (for example, an LED chip) disposed inside a lighting chamber (for example, a space) defined by the substrate and the lens (see, for example, Japanese Patent Application Laid-Open No. Sho 60-130001). This type of lighting device is shown in
In this lighting device, light beams emitted from the light source 20 at a relatively small angle with respect to the main optical axis of the light source 20 can be incident on and be refracted by the lens cut portion 70 so as to be projected in the illumination direction of the lighting device. Light beams emitted from the light source 20 at a relatively large angle with respect to the main optical axis can be incident on the lens cut portion 70, but also reflected by the same so as to be projected in the illumination direction.
In the above configuration of the lighting device, when the lens 50 is formed of a resin material, corners of the lens cut portion 70 may not be able to take an acute shape due to some molding condition restrictions (for example, draft angle of a molding die or the like). In this case, the corners thereof may take a rounded shape (with a corner R).
As a result, when light beams are emitted from the light source at an angle of about 45° or the like with respect to the main optical axis of the light source, part of the light beams may not be refracted or reflected by the lens cut portion 70, but may be reflected by the front surface of the lens 50 to be directed to, and transmit through, the outer peripheral surface (side face 50a) of the lens 50. In this case, the light beams may be projected outside of the designated projection area. This may lower the light utilization efficiency. In addition, the projected light beams may become glare light.
The presently disclosed subject matter was devised in view of these and other features, problems, and characteristics in association with the conventional art. According to an aspect of the presently disclosed subject matter, a lighting device can prevent at least some of light beams emitted from a light source at a certain angle with respect to the main optical axis of the light source from being projected out of the projection area when the light beams are not reflected by a lens cut portion, but are reflected by the front surface of the lens and pass through an outer periphery of the lens.
According to another aspect of the presently disclosed subject matter, a lighting device can include a substrate; a lens disposed to be opposed to the substrate, the lens having an outer peripheral surface and being provided with a first lens cut portion formed on a rear surface of the lens with respect to an illumination direction of the lighting device, the substrate and the lens defining a lighting chamber therebetween; a light source disposed inside the lighting chamber and having a main optical axis substantially aligned with the illumination direction, the light source configured to emit light beams at certain angles with respect to the main optical axis, some of the light beams being reflected by the first lens cut portion to be projected in the illumination direction; a reflection surface configured to reflect light beams that are emitted from the light source at a certain angle with respect to the main optical axis, reflected inside the lens, and enter the outer peripheral surface of the lens, the reflection surface being provided on or near the outer peripheral surface of the lens; and a reflecting portion configured to reflect the light beams reflected from the reflection surface to be projected in the illumination direction, the reflecting portion being disposed on a front side of the substrate with respect to the illumination direction.
In the lighting device configured as above, the reflection surface can be formed by subjecting the outer peripheral surface of the lens to a reflection treatment such as a brightness treatment.
The lens can be provided with a transmission area between the first lens cut portion and the outer peripheral surface of the lens, the transmission area being configured to allow light beams that are reflected by the reflecting portion to pass therethrough so as to be projected in the illumination direction.
In the lighting device configured as described above, the lens can be provided with a second lens cut portion in the transmission area, and the second lens cut portion can control the light distribution property of light beams passing through the transmission area.
In the lighting device configured as above, the substrate can be formed of a reflective material so that the reflecting portion can be integrated with the substrate.
In the lighting device configured according to the presently disclosed subject matter, the light source can be disposed within the lighting chamber defined by the substrate and the lens. The first lens cut portion can be formed on the rear surface of the lens with respect to the main optical axis. In the above configuration, some of the light beams emitted from the light source at a certain angle with respect to the main optical axis of the light source can be reflected by the first lens cut portion so as to be projected in the illumination direction of the lighting device.
On the other hand, when light beams are emitted from the light source at a certain angle with respect to the main optical axis of the light source, some of the light beams cannot be refracted or reflected by the first lens cut portion, but instead may be reflected by the front surface (rear side of the front surface) of the lens to be directed to, and transmit through, the outer peripheral surface (side face) of the lens. In this case, the light beams may be projected out of the projection area in the illumination direction of the lighting device without being effectively utilized. Furthermore, the light beams projected through the outer peripheral surface may become glare light. On the contrary, in an embodiment of a lighting device made in accordance with principles of the presently disclosed subject matter, a reflection surface can be configured to reflect those light beams and can be provided at the outer peripheral surface of the lens. The reflection surface can be formed by subjecting the lens outer periphery to a reflection treatment such as a brightness treatment.
Furthermore, the reflecting portion can be provided on a front surface of the substrate in order to direct the light beams reflected from the reflection surface provided at the outer peripheral surface of the lens towards the illumination direction for projection.
Specifically, when light beams are emitted from the light source at a certain angle with respect to the main optical axis of the light source, some of the light beams that cannot be refracted or reflected by the first lens cut portion, but are reflected by the front surface of the lens can be reflected by the reflection surface of the outer peripheral surface of the lens that includes the reflection surface. Then, the light beams can be reflected by the reflecting portion disposed on the front surface of the substrate to be projected in the illumination direction of the lighting device.
According to the above configuration, the lighting device can prevent at least some of the light beams emitted from a light source which are directed at a certain angle with respect to the main optical axis of the light source from being projected out of a projection area in the illumination direction of the lighting device when the light beams are not reflected by the first lens cut portion, but are instead reflected by the front surface of the lens and then pass through an outer periphery of the lens.
In another embodiment of a lighting device of the presently disclosed subject matter, the transmission area can be provided between the first lens cut portion and the outer peripheral surface of the lens in order to allow the light beams reflected by the reflecting portion to pass therethrough so as to be projected in the illumination direction.
In other words, light beams that are emitted from the light source at a certain range of angles with respect to the main optical axis of the light source and that are reflected not by the first lens cut portion but by the front surface of the lens can be reflected by the reflection surface of the outer peripheral surface of the lens. Then, the light beams can be reflected by the reflecting portion disposed on the front side of the substrate, and subsequently can pass through the transmission area disposed between the first lens cut portion and the outer peripheral surface of the lens to be projected in the illumination direction of the lighting device.
Accordingly, the lighting device as configured above can control the light beams reflected from the reflecting portion so as not to allow them to pass through the first lens cut portion that can reflect light beams from the light source, but to allow them to pass through the transmission area disposed between the first lens cut portion and the outer peripheral surface of the lens.
This lighting device can prevent the reflected light beams from the reflecting portion from being projected outside of the projection area in the illumination direction of the lighting device. Otherwise, the light beams pass through the first lens cut portion to be projected out of the projection area.
In the lighting device with the above configuration, the second lens cut portion can be formed in the transmission area in order to control the light distribution property of light passing through the transmission area. In this instance, the reflected light from the reflecting portion does not simply pass through the transmission area, but passes through the second lens cut portion in the transmission area and is controlled in terms of light distribution property. Accordingly, the lighting device can form a different light distribution pattern as compared with the case where the reflected light from the reflecting portion simply passes through the transmission area.
When the substrate is formed of a reflective material so that the reflecting portion is integrated with the substrate, the parts cost and the assembly cost as a whole can be suppressed as compared with the case where the substrate and the reflecting portion are provided separately.
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 with respect to exemplary lighting devices made in accordance with principles of the presently disclosed subject matter with reference to the accompanying drawings. A first exemplary embodiment will be discussed hereinafter with reference to
In the lighting device of the first exemplary embodiment, as shown in
The lighting device of the present exemplary embodiment includes a lens 2. As shown in
In the lighting device of the present exemplary embodiment, as shown in
In the lighting device of the exemplary embodiment configured as described above, and as shown in
Specifically, light beams L1 emitted from the light source 4 along the main optical axis L of the light source 4 can pass through the transmission surface 2a1 of the lens cut portion 2a of the lens 2, and then can pass through a front surface 2a12 of the lens 2 to be projected in the illumination direction of the lighting device.
The light beams L2 emitted from the light source 4 at a small angle with respect to the main optical axis L of the light source 4 can pass through the transmission surface 2a1 of the lens cut portion 2a of the lens 2, and then can be refracted thereby and pass through the front surface 2a12 of the lens 2 to be projected in the illumination direction of the lighting device.
As shown in
Specifically, the light beams L3 emitted from the light source 4 at a larger angle than that of the light beams L2 with respect to the main optical axis L of the light source 4 can pass through the transmission surface 2a2 of the lens cut portion 2a of the lens 2, and then can be reflected by the reflection surface 2a3 and pass through the front surface 2a12 of the lens 2 to be projected in the illumination direction of the lighting device.
As shown in
Specifically, the light beams L4 emitted from the light source 4 at a larger angle than that of the light beams L3 with respect to the main optical axis L of the light source 4 can pass through the transmission surface 2a4 of the lens cut portion 2a of the lens 2, and then can be reflected by the reflection surface 2a5 and pass through the front surface 2a12 of the lens 2 to be projected in the illumination direction of the lighting device.
As shown in
Specifically, the light beams L5 emitted from the light source 4 at a larger angle than that of the light beams L4 with respect to the main optical axis L of the light source 4 can pass through the transmission surface 2a6 of the lens cut portion 2a of the lens 2, and then can be reflected by the reflection surface 2a7 and pass through the front surface 2a12 of the lens 2 to be projected in the illumination direction of the lighting device.
Furthermore, as shown in
Specifically, the light beams L6 emitted from the light source 4 at a larger angle than that of the light beams L5 with respect to the main optical axis L of the light source 4 can pass through the transmission surface 2a8 of the lens cut portion 2a of the lens 2, and then can be reflected by the reflection surface 2a9 and pass through the front surface 2a12 of the lens 2 to be projected in the illumination direction of the lighting device.
In the lighting device of the first exemplary embodiment, as shown in the drawings, the lens 2 can have an outer peripheral surface 2a11 that is subjected to a reflection treatment including a brightness treatment such as aluminum vapor deposition or the like to form a reflecting film 5 thereon (reflection surface).
In particular, as shown in
Furthermore, as shown in
Accordingly, as shown in
Furthermore, as shown in
The thus configured lighting device, when applied to a roadway illumination assembly or an outdoor illumination assembly, can prevent light beams emitted from the light source from becoming glare light when the light beams are projected out of the projection area in the illumination direction of the lighting device.
A description will now be given of a second exemplary embodiment of a lighting device made in accordance with principles of the presently disclosed subject matter. The lighting device of the second exemplary embodiment is configured in the same manner as the lighting device of the first exemplary embodiment except for the following points. Accordingly, the lighting device of the second exemplary embodiment can provide the same or similar advantageous effects as those of the lighting device of the first exemplary embodiment except possibly with respect to the following points.
A description will now be given of a third exemplary embodiment of a lighting device made in accordance with principles of the presently disclosed subject matter. The lighting device of the third exemplary embodiment can be configured in the same manner as the lighting device of the first exemplary embodiment except for the following points. Accordingly, the lighting device of the third exemplary embodiment can provide the same or similar advantageous effects as those of the lighting device of the first exemplary embodiment except possibly for the following points.
In the lighting device of the first exemplary embodiment, as shown in
Specifically, in the lighting device of the first exemplary embodiment, the light beams L8 that are emitted from the light source 4 at a certain angle with respect to the main optical axis L of the light source 4 and pass through the transmission area 2a10 of the lens 2 can be projected in the illumination direction at a relatively large angle with respect to the main optical axis L of the light source 4. On the contrary, since the lighting device of the third exemplary embodiment has the second lens cut portion 2a13 formed in the transmission area 2a10 of the lens 2, the light beams L8 that are emitted from the light source 4 at the certain angle with respect to the main optical axis L of the light source 4 and pass through the second lens cut portion 2a13 in the transmission area 2a10 of the lens 2 can be projected in the illumination direction at a relatively small angle with respect to the main optical axis L of the light source 4. This can improve the light distribution property in the illumination direction.
Note that the lighting devices of the present exemplary embodiments described above are configured to take a square shape when viewed from its front as shown in
The above described exemplary embodiments and modifications can be combined with each other in accordance with the intended applications.
The lighting devices of the presently disclosed subject matter can be applied to a roadway illumination assembly, an outdoor illumination assembly, and the like.
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 invention. 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.
Number | Date | Country | Kind |
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2008-003877 | Jan 2008 | JP | national |
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20090180286 A1 | Jul 2009 | US |