Patent Publication Number: US-10779372-B1

Title: Lighting device with communication function

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The disclosure generally relates to a lighting device, and more particularly, to a lighting device with a communication function. 
     Description of the Related Art 
     With the advancement of technology, future street light devices will have the function of connecting to the Internet, so as to achieve the goal of building smart cities. However, the design space in a street light device is very limited, and it cannot easily accommodate Internet-relative components. Accordingly, there is a need to propose a lighting device with a communication function for solving the problems of the prior art. 
     BRIEF SUMMARY OF THE INVENTION 
     In a preferred embodiment, the invention is directed to a lighting device with a communication function. The light device includes a frequency selective surface, a control circuit board, and at least one light-emitting diode. The frequency selective surface includes at least one first metal piece. The first metal piece has an opening. The light-emitting diode is disposed on the control circuit board. The light-emitting diode is substantially aligned with the opening of the first metal piece. 
     In some embodiments, the frequency selective surface covers a central operation frequency equal to about 28 GHz, about 39 GHz, or about 60 GHz. 
     In some embodiments, the first metal piece substantially has a hollow square shape, and the opening substantially has a relatively small square shape. 
     In some embodiments, an edge of the first metal piece has a notch connected to the opening, such that the first metal piece substantially has a C-shape. 
     In some embodiments, the lighting device further includes at least one transparent lens embedded in the opening of the first metal piece. 
     In some embodiments, the perimeter of the first metal piece is smaller than 1 wavelength of the central operation frequency. 
     In some embodiments, the frequency selective surface further includes at least one second metal piece without any openings. 
     In some embodiments, the second metal piece substantially has a solid square shape. 
     In some embodiments, the perimeter of the second metal piece is smaller than 1 wavelength of the central operation frequency. 
     In some embodiments, the distance between the first metal piece and the second metal piece is smaller than 0.1 wavelength of the central operation frequency. 
     In some embodiments, the lighting device further includes an antenna element and a ground metal plane. The antenna element is disposed adjacent to the frequency selective surface. The antenna element is disposed between the frequency selective surface and the ground metal plane, or the frequency selective surface is disposed between the antenna element and the ground metal plane. 
     In some embodiments, the distance between the antenna element and the frequency selective surface is smaller than 0.5 wavelength of the central operation frequency. 
     In some embodiments, the lighting device further includes at least one switch element and at least one connection metal element. The switch element is selectively closed or opened. The first metal piece is selectively coupled through the connection metal element and the switch element to the ground metal plane. 
     In some embodiments, the central operation frequency of the frequency selective surface can be adjusted by controlling the switch element. 
     In some embodiments, the reflective direction of the frequency selective surface can be adjusted by controlling the switch element. 
     In some embodiments, the frequency selective surface includes a plurality of first metal pieces and a plurality of second metal pieces. The lighting device includes a plurality of light-emitting diodes. 
     In some embodiments, each of the first metal pieces has an opening. The light-emitting diodes are substantially aligned with the openings of the first metal pieces, respectively. 
     In some embodiments, the first metal pieces are substantially surrounded by the second metal pieces. 
     In some embodiments, the lighting device further includes a transparent substrate. The frequency selective surface is disposed on the transparent substrate. 
     In some embodiments, the lighting device is implemented with a street light device. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIG. 1A  is a top view of a lighting device according to an embodiment of the invention; 
         FIG. 1B  is a sectional view of a lighting device according to an embodiment of the invention; 
         FIG. 2  is a top view of a first metal piece according to an embodiment of the invention; 
         FIG. 3A  is a top view of a first metal piece according to another embodiment of the invention; 
         FIG. 3B  is a top view of a first metal piece according to another embodiment of the invention; 
         FIG. 4A  is a top view of a lighting device according to another embodiment of the invention; 
         FIG. 4B  is a sectional view of a lighting device according to another embodiment of the invention; 
         FIG. 5A  is a top view of a lighting device according to an embodiment of the invention; 
         FIG. 5B  is a sectional view of a lighting device according to an embodiment of the invention; 
         FIG. 6A  is a sectional view of a lighting device according to another embodiment of the invention; 
         FIG. 6B  is a sectional view of a lighting device according to another embodiment of the invention; 
         FIG. 7  is a sectional view of a lighting device according to an embodiment of the invention; 
         FIG. 8  is a sectional view of a lighting device according to another embodiment of the invention; and 
         FIG. 9  is a diagram of a frequency selective surface according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In order to illustrate the foregoing and other purposes, features and advantages of the invention, the embodiments and figures of the invention will be described in detail as follows. 
     Certain terms are used throughout the description and following claims to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms “include” and “comprise” are used in an open-ended fashion, and thus should be interpreted to mean “include, but not limited to . . . ”. The term “substantially” means the value is within an acceptable error range. One skilled in the art can solve the technical problem within a predetermined error range and achieve the proposed technical performance. Also, the term “couple” is intended to mean either an indirect or direct electrical connection. Accordingly, if one device is coupled to another device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections. 
       FIG. 1A  is a top view of a lighting device  100  according to an embodiment of the invention.  FIG. 1B  is a sectional view of the lighting device  100  according to an embodiment of the invention (along a sectional line LL 1  of  FIG. 1A ). Please refer to  FIG. 1A  and  FIG. 1B  together. The smart lighting device  100  has a communication function. For example, the lighting device  100  may be implemented with a street light device, but it is not limited thereto. As shown in  FIG. 1A  and  FIG. 1B , the lighting device  100  includes a frequency selective surface (FSS)  110 , a control circuit board  150 , and at least one light-emitting diode (LED)  160 . It should be understood that the lighting device  100  may further include other components, such as a light holder, a power supply module, and a housing, although they are not displayed in  FIG. 1A  and  FIG. 1B . 
     The frequency selective surface  110  includes at least one first metal piece  120 . The first metal piece  120  has an opening  140 . For example, the first metal piece  120  may substantially have a hollow square shape, and the opening  140  may substantially have a relatively small square shape. In alternative embodiments, the shapes of the first metal piece  120  and its opening  140  are adjustable according to different requirements. The frequency selective surface  110  can cover a central operation frequency, so as to achieve the function of communication. For example, the aforementioned central operation frequency may be equal to about 28 GHz, about 39 GHz, or about 60 GHz corresponding to 5G and WiGig communication systems, but it is not limited thereto. The control circuit board  150  may be a flame retardant  4  (FR4) substrate, a printed circuit board (PCB), or a flexible circuit board (FCB). The control circuit board  150  is configured to carry a variety of circuit components and provide electric power for the light-emitting diode  160 . The light-emitting diode  160  is disposed on the control circuit board  150 . The light-emitting diode  160  is substantially aligned with the opening  140  of the first metal piece  120 . That is, the opening  140  of the first metal piece  120  has a vertical projection on the control circuit board  150 , and the whole light-emitting diode  160  is inside the vertical projection of the opening  140 . With such a design, the light generated by the light-emitting diode  160  (as the dash-line arrow of  FIG. 1B ) can be transmitted through the opening  140  of the first metal piece  120 . 
     The following embodiments will introduce a variety of configurations of the frequency selective surface  110 . It should be understood that these figures and descriptions are merely exemplary, rather than limitations of the invention. 
       FIG. 2  is a top view of the first metal piece  120  according to an embodiment of the invention. In the embodiment of  FIG. 2 , the lighting device  100  further includes a transparent lens  270 , which is embedded in the opening  140  of the first metal piece  120 . In alternative embodiments, the first metal piece  120  with the structure of the opening  140  is formed on the transparent lens  270  by using the method of plastic surface treatment metal plating (e.g., laser direct structuring). For example, the transparent lens  270  may substantially have a square shape, so as to fit the shape of the opening  140  of the first metal piece  120 . The transparent lens  270  is configured to adjust the focal length or the light scattering of the light-emitting diode  160 . In some embodiments, the perimeter L 1  of the first metal piece  120  is smaller than 1 wavelength (1λ) of the central operation frequency of the frequency selective surface  110 , such as 0.5 wavelength (λ/2) or 0.25 wavelength (λ/4). 
       FIG. 3A  is a top view of a first metal piece  320  according to another embodiment of the invention. The first metal piece  320  may be applied to the frequency selective surface  110  of  FIG. 1 . In the embodiment of  FIG. 3A , an edge  321  of the first metal piece  320  has a notch  325 . The notch  325  is connected to the opening  340  of the first metal piece  320 , such that the first metal piece  320  substantially has a C-shape or a U-shape. In some embodiments, the perimeter L 2  of the first metal piece  320  is smaller than 1 wavelength (1λ) of the central operation frequency of the frequency selective surface  110 , such as 0.5 wavelength (λ/2) or 0.25 wavelength (λ/4). 
       FIG. 3B  is a top view of a first metal piece  360  according to another embodiment of the invention. The first metal piece  360  may be applied to the frequency selective surface  110  of  FIG. 1 . In the embodiment of  FIG. 3B , the first metal piece  360  has a plurality of openings  371 ,  372 ,  373  and  374 . The number of openings  371 ,  372 ,  373  and  374  is not limited. For example, each of the openings  371 ,  372 ,  373  and  374  may substantially have a small square shape. In alternative embodiments, the shapes of the first metal piece  360  and its openings  371 ,  372 ,  373  and  374  are adjustable according to different requirements. The light-emitting diode  160  may be substantially aligned with any of the openings  371 ,  372 ,  373  and  374 . Furthermore, if the lighting device  100  includes a plurality of light-emitting diodes  160 , these light-emitting diodes  160  may be substantially aligned with the openings  371 ,  372 ,  373  and  374  of the first metal piece  360 , respectively. In some embodiments, the perimeter L 3  of the first metal piece  360  is smaller than 1 wavelength (1λ) of the central operation frequency of the frequency selective surface  110 , such as 0.5 wavelength (λ/2) or 0.25 wavelength (λ/4). 
       FIG. 4A  is a top view of a lighting device  400  according to another embodiment of the invention.  FIG. 4B  is a sectional view of the lighting device  400  according to another embodiment of the invention (along a sectional line LL 2  of  FIG. 4A ). Please refer to  FIG. 4A  and  FIG. 4B  together.  FIG. 4A  and  FIG. 4B  are similar to  FIG. 1A  and  FIG. 1B . In the embodiment of  FIG. 4A  and  FIG. 4B , a frequency selective surface  410  of the lighting device  400  includes at least one first metal piece  120  and at least one second metal piece  430 . The second metal piece  430  does not have any openings. For example, the second metal piece  430  may substantially have a solid square shape, whose size may be the same as the size of the first metal piece  120 . In alternative embodiments, the shape of the second metal piece  430  is adjustable according to different requirements. Since the effective resonant length of the second metal piece  430  is different from that of the first metal piece  120 , the incorporation of the second metal piece  430  can increase the operation bandwidth of the frequency selective surface  410 . In some embodiments, the perimeter L 4  of the second metal piece  430  is smaller than 1 wavelength (1λ) of the central operation frequency of the frequency selective surface  410 , such as 0.5 wavelength (λ/2) or 0.25 wavelength (λ/4), and the distance D 1  between the first metal piece  120  and the second metal piece  430  is smaller than 0.1 wavelength (λ/10) of the central operation frequency of the frequency selective surface  410 . It should be noted that the above ranges of the perimeters and distances are calculated and obtained according to many experiment results, and they help to optimize the selection performance of each frequency selective surface. 
       FIG. 5A  is a top view of a lighting device  500  according to an embodiment of the invention.  FIG. 5B  is a sectional view of the lighting device  500  according to an embodiment of the invention (along a sectional line LL 3  of  FIG. 5A ). Please refer to  FIG. 5A  and  FIG. 5B  together.  FIG. 5A  and  FIG. 5B  are similar to  FIG. 1A  and  FIG. 1B . In the embodiment of  FIG. 5A  and  FIG. 5B , the lighting device  500  includes a frequency selective surface  510 , a control circuit board  550 , and a plurality of light-emitting diodes  560 . The light-emitting diodes  560  are all disposed on the control circuit board  550 . The frequency selective surface  510  has a periodic structure and includes a plurality of first metal pieces  520  and a plurality of second metal pieces  530 . The number of first metal pieces  520  may be greater than or equal to the number of light-emitting diodes  560 . Specifically, each of the first metal pieces  520  has an opening  540 , and the light-emitting diodes  560  are substantially aligned with the openings  540  of the first metal pieces  520 , respectively. Thus, the light generated by the light-emitting diodes  560  (as the dash-line arrow of  FIG. 5B ) can be transmitted through the openings  540  of the first metal pieces  520 . In some embodiments, the combination of the second metal pieces  530  substantially has a hollow rectangular shape, and the first metal pieces  520  are substantially surrounded by the second metal pieces  530 . According to practical measurements, such an arrangement of the second metal pieces  530  surrounding the first metal pieces  520  can further increase the operation bandwidth of the frequency selective surface  510 . 
       FIG. 6A  is a sectional view of a lighting device  600  according to another embodiment of the invention.  FIG. 6A  is similar to  FIG. 5B . In the embodiment of  FIG. 6A , the lighting device  600  includes a frequency selective surface  510 , a control circuit board  550 , a plurality of light-emitting diodes  560 , an antenna element  680 , and a ground metal plane  690 . The shapes and types of the antenna element  680  are not limited in the invention. For example, the antenna element  680  may be a monopole antenna, a dipole antenna, a loop antenna, a patch antenna, or a chip antenna. The antenna element  680  is adjacent to the frequency selective surface  510 . It should be noted that the term “adjacent” or “close” over the disclosure means that the distance (spacing) between two corresponding elements is smaller than a predetermined distance (e.g., 10 mm or shorter), but does not mean that the two corresponding elements directly touch each other (i.e., the aforementioned distance/spacing therebetween is reduced to 0). The ground metal plane  690  can provide a ground voltage. The antenna element  680  is disposed between the frequency selective surface  510  and the ground metal plane  690 . The antenna element  680  is configured to generate electromagnetic waves. The electromagnetic waves may be partially transmitted through the frequency selective surface  510 , and partially reflected by the frequency selective surface  510  and the ground metal plane  690 . Within the central operation frequency of the frequency selective surface  510 , the electromagnetic waves of the antenna element  680  can generate constructive interference due to the frequency selective surface  510 , thereby increasing the total gain of the antenna element  680 . In order to enhance the constructive interference, the distance D 2  between the antenna element  680  and the frequency selective surface  510  may be smaller than 0.5 wavelength (λ/2) of the central operation frequency of the frequency selective surface  510 , such as 0.25 wavelength (λ/4). 
       FIG. 6B  is a sectional view of a lighting device  650  according to another embodiment of the invention.  FIG. 6B  is similar to  FIG. 6A . In the lighting device  650  of the embodiment of  FIG. 6B , the frequency selective surface  510  is changed and disposed between the antenna element  680  and the ground metal plane  690 , such that the electromagnetic waves of the antenna element  680  can be reflected by the frequency selective surface  510  and the ground metal plane  690 . Similarly, within the central operation frequency of the frequency selective surface  510 , the electromagnetic waves of the antenna element  680  can generate constructive interference due to the frequency selective surface  510 , thereby increasing the total gain of the antenna element  680 . In order to enhance the constructive interference, the distance D 3  between the antenna element  680  and the frequency selective surface  510  may be smaller than 0.5 wavelength (λ/2) of the central operation frequency of the frequency selective surface  510 , such as 0.25 wavelength (λ/4). 
       FIG. 7  is a sectional view of a lighting device  700  according to an embodiment of the invention. In the embodiment of  FIG. 7 , the lighting device  700  further includes a transparent substrate  750 . A plurality of first metal pieces  520  and a plurality of second metal pieces  530  of a frequency selective surface  710  are all disposed on the transparent substrate  750 . For example, the transparent substrate  750  may be made of a polycarbonate material. It should be noted that the transparent substrate  750  neither blocks the light generated by a plurality of light-emitting diodes  560 , nor interferes with the transmission of any electromagnetic waves. Thus, the transparent substrate  750  is used as a good carrier of the frequency selective surface  710 . 
       FIG. 8  is a sectional view of a lighting device  800  according to another embodiment of the invention. In the embodiment of  FIG. 8 , the lighting device  800  includes a frequency selective surface  810 , a control circuit board  550 , at least one light-emitting diode  560 , a transparent substrate  750 , a ground metal plane  690 , a switch element  860 , and a connection metal element  870 . The frequency selective surface  810  includes at least one first metal piece  520 . The first metal piece  520  has an opening  540 . The first metal piece  520  is disposed on the transparent substrate  750 . The light-emitting diode  560  is disposed on the control circuit board  550 . The control circuit board  550  is disposed on the ground metal plane  690 . The light generated by the light-emitting diode  560  (as the dash-line arrow of  FIG. 8 ) can be transmitted through the transparent substrate  750  and the opening  540  of the first metal piece  520 . The connection metal element  870  may be a via element, a pogo pin, or a metal spring, but it is not limited thereto. The connection metal element  870  and the switch element  860  can penetrate the transparent substrate  750  and the control circuit board  550 . The connection metal element  870  is coupled between the first metal piece  520  and the switch element  860 . The switch element  860  is coupled to the ground metal plane  690 . Specifically, the switch element  860  is selectively closed or opened according to a control signal, such that the first metal piece  520  is selectively coupled through the connection metal element  870  and the switch element  860  to the ground metal plane  690 . The aforementioned control signal may be generated by a processor according to a user&#39;s input. In some embodiments, a central operation frequency of the frequency selective surface  810  can be adjusted by controlling the switch element  860 . This not only increases the operation bandwidth of the frequency selective surface  810 , but also makes the frequency selective surface  810  have different electromagnetic reflective characteristics due to the change in the operation frequency. It should be noted that the design of the switch element  860  and the connection metal element  870  of  FIG. 8  can be applied to any first metal piece or any second metal piece of the frequency selective surface in each of the above embodiments. 
       FIG. 9  is a diagram of a frequency selective surface  910  according to an embodiment of the invention. The frequency selective surface  910  includes the switch element  860  and the connection metal element  870  of  FIG. 8  (not shown). A signal transmitter, such as an antenna element  980  for implementation, transmits electromagnetic waves toward the frequency selective surface  910 . If the switch element  860  is closed, one or more first metal pieces  520  of the frequency selective surface  910  will be grounded, such that the electromagnetic waves of the antenna element  980  can be reflected toward a first direction  991  by the frequency selective surface  910 . Conversely, if the switch element  860  is opened, one or more first metal pieces  520  of the frequency selective surface  910  will be floating, such that the electromagnetic waves of the antenna element  980  can be reflected toward a second direction  992  by the frequency selective surface  910 . The second direction  992  is different from the first direction  991 . That is, a reflective direction of the frequency selective surface  910  can be adjusted by controlling the switch element  680 . 
     The invention proposed a novel lighting device for integrating a frequency selective surface with a light-emitting diode, so as to provide both the functions of communication and lighting. Generally, the invention has at least the advantages of small size, high antenna gain, and beautiful device appearance, and it is suitable for application in a variety of communication or lighting devices. 
     Note that the above element sizes, element shapes, and frequency ranges are not limitations of the invention. A designer can fine-tune these settings or values according to different requirements. It should be understood that the lighting device of the invention is not limited to the configurations of  FIGS. 1-9 . The invention may include any one or more features of any one or more embodiments of  FIGS. 1-9 . In other words, not all of the features displayed in the figures should be implemented in the structure of lighting device of the invention. 
     Use of ordinal terms such as “first”, “second”, “third”, etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having the same name (but for use of the ordinal term) to distinguish the claim elements. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the invention. It is intended that the standard and examples be considered as exemplary only, with a true scope of the disclosed embodiments being indicated by the following claims and their equivalents.