FIELD

Embodiments of the present disclosure generally relates to the field of lighting, and particularly, to a lighting device and a luminaire including such a lighting device.

BACKGROUND

As energy conservation is increasing concerned, lighting devices using LEDs as light sources are increasingly used to replace incandescent luminaires in lighting applications. Light distribution of conventional LED lighting devices is not satisfactory since some areas of the lighting devices are brighter and some areas are darker. Lor example, as for a globular bulb, a bright area appears near top of the bulb, and light intensity at this area is greater than at other areas in the diffuser. This bright area often causes a dazzling feeling to the user while it causes insufficient light intensity at other areas.

At present, there is no solution that can well solve the problem of uneven distribution of light intensity for traditional bulbs. Therefore, it is desirable to improve the conventional lighting device to make the light intensity distribution of the lighting device more uniform.

SUMMARY

One of objectives of the present disclosure is to provide a lighting device which can improve uniformity of light distribution and user experience.

In a first aspect of the present disclosure, there is provided a lighting device. The lighting device comprises: a light source comprising at least one LED; and a light transmissive cover surrounding the at least one LED, the light transmissive cover comprising a bright area at which light intensity of the light emitted by the at least one LED is greater than the light intensity at other areas of the light transmissive cover; wherein at least a portion of the bright area of the light transmissive cover is provided with a reflective area on for reflecting light emitted from the at least one LED. In an embodiment of the present disclosure, with the reflective area, a beam angle of the lighting device can be increased, so that luminance of the lighting device is more uniform, and a dazzling feeling of the lighting device at the bright area is reduced.

In an embodiment of the present disclosure, the reflective area includes a reflective spot-like pattern. According to an embodiment of the present disclosure, the reflective area comprises a reflective pattern of phyllotaxis. The reflective area may include various patterns. According to one embodiment of the present disclosure, the spot-like pattern is selected one or more of the following: a dot, a cluster of dots, a star shape, a polygon, and combinations thereof. The use of a spot-like pattern or a pattern of phyllotaxis can enhance appearance of the lighting device.

In an embodiment of the present disclosure, a density of the pattern gradually becomes sparse from a central area of the reflective area toward a periphery of the reflective area, and the light intensity of the light emitted by the at least one LED is maximal at the central area. Thereby, the light intensity of the lighting device changes smoothly, such that the light intensity distribution of the lighting device can be further made uniform. The beam angle of the lighting device can be further increased.

In an embodiment of the present disclosure, the pattern includes a pattern formed by a laser marking process. According to an embodiment of the present disclosure, the pattern includes a pattern formed by a printing process. According to an embodiment of the present disclosure, the pattern includes a pattern formed by printing ink. Thereby, the pattern can be easily formed in a simple and low-cost manner.

In an embodiment of the present disclosure, the lighting device is a globular bulb, a columnar bulb, a spiral bulb, or a candle bulb. In the case where the lighting device is a globular bulb, the reflective area is typically arranged at top of the light transmissive cover.

In a second aspect of the present disclosure, there is provided a luminaire comprising the lighting device according to the above aspect. Therefore, the luminance of the luminaire is more uniform, and the dazzling feeling of the lighting device in the bright area is reduced.

As will be understood from the following description, the lighting device and the luminaire provided herein can provide more uniform luminance, reducing glare, thereby enhancing the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objectives, features and advantages of embodiments of the present disclosure will be made clear through the following detailed depictions with reference to figures. In the figures, several embodiments of the present disclosure are shown in an exemplary and non-restrictive manner, wherein:

FIG. 1 illustrates a structural schematic diagram of a conventional lighting device according to an example embodiment of the present disclosure;

FIG. 2 illustrates a structural schematic diagram of a lighting device according to an example embodiment of the present disclosure;

FIGs. 3-5 illustrate schematic diagrams of an example embodiment that may be used in a pattern of an reflective area in FIG. 2 respectively;

FIG. 6 illustrates a contrast diagram of light intensity distribution between a conventional lighting device and a lighting device according to an embodiment of the present disclosure;

FIG. 7 illustrates a contrast diagram of light luminance between a conventional lighting device and a lighting device according to an embodiment of the present disclosure;

FIGs. 8 and 9 illustrate a contrast diagram of light intensity distribution between a conventional lighting device and a lighting device according to an embodiment of the present disclosure respectively; and

FIG. 10 illustrates a contrast diagram of light intensity distribution between a conventional lighting device and a lighting device according to another embodiment of the present disclosure.

DETAIFED DESCRIPTION

Hereinafter, several example embodiments shown in the drawings will be referred to describe the principle of the present disclosure. It is be understood that these embodiments are described only for enabling those skilled in the art to better understand and then further implement the present disclosure, not intended to limit the scope of the present disclosure in any manner. It is noted that wherever practicable similar or like reference numbers may be used in the figures, and may indicate similar or like functionality. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the present disclosure described therein. Structures of a lighting device according to an example embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings. Although the present disclosure takes a globular bulb as an example of a lighting device to describe the inventive concept of the present disclosure, it is be understood that the inventive concepts of the present disclosure may be applied to other types of lighting devices including, but not limited to, for example, globular bulb, a columnar bulb, a spiral bulb, or a candle bulb , etc.

FIG. 1 shows a schematic structural view of a conventional lighting device. As shown in FIG. 1, the lighting device includes a light source 10' and a light transmissive cover 20' surrounding the light source, and the light source 10' includes at least one LED. A schematic view of an optical path of light from the LED is also shown, and light emitted from the LED is transmitted through the light transmissive cover 20’ to the surroundings. The light transmissive cover 20’ may be made of glass or plastic.

With such a conventional lighting device, areas with different luminance are formed around the lighting device due to lighting characteristics of a LED itself. In the case of a globular bulb, a bright area appears near, for example, top of the bulb, and the intensity at this area is greater than that at other areas of the light transmissive cover. It is understood that, due to illuminating characteristics of the lighting device and the use of the lighting device, the bright area herein does not mean an area where the light intensity is the brightest, but includes an area where the light intensity is the brightest and areas extending from the brightest area to the periphery which have light intensity greater than other areas.

FIGs. 6 and 8 show schematic diagrams of light intensity distributions of a conventional lighting device in a Cartesian coordinate system and a polar coordinate system respectively. As shown by a curve 600’ in FIG. 6 and a curve 800’ in FIG. 8, luminance at the vicinity of top of the bulb is significantly higher than the luminance at other areas of the bulb. In other words, presence of such a bright area will give the user a dazzling feeling while it causes insufficient light intensity in other areas.

In order to at least partially solve the above problems, in accordance with an embodiment of the present disclosure, at least a portion of the bright area of the light transmissive cover 20 is provided with a reflective area 30 for reflecting light emitted from the at least one LED.

FIG. 2 illustrates a schematic structural view of a lighting device according to an example embodiment of the present disclosure. As shown in FIG. 2, a reflective area 30 is included at top of the lighting device. Arrows Pl, P2 in FIG. 2 illustrate an example optical path of light emitted from a light source 10 (e.g., one or more LED of any type). It can be seen that the reflective area 30 is adapted to reflect a portion of the light emitted from the light source 10 back into the interior of the light transmissive cover 20 and to transmit portion of the light emitted from the light source 10 out of the light transmissive cover.

In aid of the reflective area 30, the light intensity at the top of the lighting device is lowered. Since the reflective area 30 reflects a portion of the light in different directions back to the inside of the light transmissive cover 20, the light intensity at other areas can be enhanced. As a result, the arrangement of the reflective area increases the beam angle of the lighting device, so that luminance of the lighting device is more uniform, and dazzling feeling of the lighting device at the bright area is reduced.

According to some embodiments of the present disclosure, the reflective area 30 may include a spot-like pattern. Shapes of the spot-like pattern are not particularly limited as long as at least partial incident light can be reflected. As an example, in some

embodiments, the spot-like pattern is selected one or more of the following: a dot, a cluster of dots, a star shape, a polygon, and combinations thereof.

In some embodiments, the pattern of the reflective area 30 is not limited to the spot-like pattern, and may include a petal pattern, a phyllotaxis pattern, or a combination thereof (not shown). Such a pattern can further enhance the appearance of the lighting device. For example, in some embodiments, the pattern may be formed in the shape of a petal, which may be the petals of various plants, or may be in the shape of various designed petals that are aesthetically pleasing. Also, shape of the leaves in the pattern of phyllotaxis herein may be a leaf shape of various plants, or may be a shape of various aesthetic designed leaves. In some embodiments, a repeating spiral pattern may be used as a phyllotaxis pattern, as is shown in Fig. 3, which can create an optical effect of crisscrossing spirals. By adopting the phyllotaxis patterns, a natural light effect can be provided in a cost-efficient way.

In some embodiments, the pattern of the reflective area 30 may be a pattern formed by a laser marking process, and the pattern of the reflective area 30 may include a pattern formed by a printing process. Further, the pattern may be formed by printing ink. Preferably, the pattern of the reflective area 30 is arranged on the outer surface of the light transmissive cover 20. As a result, the pattern can be easily formed in a simple and low-cost manner.

In some embodiments, the reflectivity rate of the pattern of the reflective area 30 is 60% to 95%, and the optical efficiency and the beam angle are further adjusted by providing patterns with different reflectivity rates. In some embodiments, density of the pattern may gradually become sparse from a central area of the reflective area toward the periphery of the reflective area, and the light intensity of the light emitted from the at least one LED is maximal at the central area. FIGs. 3 to 5 show schematic views of an example embodiment of patterns of the reflective area respectively. In the bright area, the pattern is arranged in a manner of gradually changing from an area with a maximal light intensity to an area with a lower light intensity. In this way, the light intensity of the lighting device can be smoothly changed, the light intensity distribution can be further made uniform, and the beam angle of the lighting device can be further increased.

Technical effects according to the embodiments of the present disclosure will become apparent by comparison as shown in FIGs. 6 to 9. FIG. 6 shows a schematic contrast diagram of light intensity distributions between a conventional lighting device and a lighting device according to some embodiments of the present disclosure; FIG. 7 shows a schematic contrast diagram of light luminance between a conventional lighting device and a lighting device according to some embodiments of the present disclosure in a Cartesian coordinate system; FIGs. 8 and 9 show schematic diagram of light intensity distributions between a conventional lighting device and a lighting device according to some embodiments of the present disclosure respectively.

As shown in FIG. 6, as compared to the light distribution curve 600' of the conventional lighting device, the light intensity distribution curve 600 of the lighting device according to the present disclosure is significantly reduced at the central area and the beam angle in other regions is significantly increased.

As shown in FIG. 7, the light luminance curve 700 of the lighting device according to the present disclosure is more uniform and softer in the central area than the light luminance curve 700’ of the conventional lighting device, and it can also be clearly seen that the beam angle is significantly increased.

Fikewise, the technical effects according to some embodiments of the present disclosure can also be clearly seen by comparison between the light intensity distribution diagrams of the lighting devices in the polar coordinates shown in FIGs. 8 and 9 respectively. Compared with FIG. 8, the light intensity distribution diagram 900 in the polar coordinates of the lighting device according to some embodiments of the present disclosure is more uniform and softer in the central area, and the beam angle is significantly increased, and thus the user can feel the light more comfortable. In some embodiments, the pattern is not arranged in a manner of gradually changing from an area with maximal light intensity toward an area with lower light intensity. FIG. 10 shows a schematic contrast diagram between light intensity distribution curve 100’ according to a conventional lighting device and light intensity distribution curve 100 of a lighting device according to further embodiments of the present disclosure in a Cartesian coordinate system. As shown in the figure, since the pattern is not arranged in a manner of gradually changing from an area with a maximal light intensity to an area with a lower light intensity, the beam angle is also increased and the light intensity distribution is improved. But there is possibility that light intensity in the central area may be insufficient.

According to an embodiment of the present disclosure, there is also provided a luminaire comprising the above lighting device. The luminaire has the above-described advantages with respect to the lighting device. To avoid repetition, a detailed description thereof will be omitted.

It is to be understood that the above depictions are provided for illustration purpose, not for restrictive purpose. Those skilled in the art should understand that the present invention may be implemented in other implementation modes departing from these specific details. Furthermore, in order to make the present invention apparent, unnecessary details of known functions and structures are omitted in the current description.

Although specific embodiments are already illustrated and described, those skilled in the art can recognize that any arrangements intended to achieve the same purpose may be used to replace the illustrated specific embodiments, and the present invention has other applications under other environments. The present application is intended to cover any modifications or variations of the present invention. The following claims should not be understood in a way that the scope of the present invention is limited to the specific embodiments described here.