Patent Application
20210288717
Embodiments of the subject matter disclosed herein generally relate to a device for illuminating and also transmitting information in a wireless manner, and more particularly, to a laser light bank device that converts electrical power into light energy for illumination and light waves for communication.
Light sources that generate electromagnetic radiation in the visible color regime have a variety of applications including lighting, illumination, imaging and display. Incandescent and gas discharge lamps have been widely used in the past few decades. The incandescent light bulb utilizes a tungsten filament sealed in a vacuum glass bulb, which is powered by alternating current (AC) or direct current (DC) power supply. The white light sources are widely used in both indoor and outdoor applications, including household, buildings, streets, halls etc. The technology of incandescent light bulb has, unfortunately, many drawbacks. One of them is that the conventional incandescent bulb converts over 80% of the electrical energy into thermal energy, and only less than 20% of the electrical power is utilized for generating white light. In addition, the conventional incandescent lamp routinely fails and has a lifespan of less than 1,200 hours owing to the thermal expansion and contraction of the filament element during operation.
To overcome some of the disadvantages of the conventional incandescent lamp, the fluorescent lamp and the compact fluorescent lamp (CFL) have been developed. In the CFL lamp, there are electrodes placed in a sealed tube, which is filled with a halogen gas and typically together with mercury. Once the lamp is powered on, electrons that are bound to the mercury atoms are excited to states where they will radiate ultraviolet light as they return to a lower energy level. The tube in the CFL lamp is coated with a phosphor material, which then coverts the emitted UV light into visible light. CFL lamp can be manufactured in a variety of fixtures and forms to fit in different applications, such as building structure lighting. However, the fluorescent lamp has a drawback as its poses an environmental risk due to the mercury gas in the lighting tube.
A more recent development in the illumination field has come due to the light emitting diode (LED). LED that emit white light has rapidly emerged as the solid-state lighting technology with advantages of high efficiency, long lifespan, and non-toxicity. LED lamp is based on a semiconductor light emitter, typically constructed based on a p-n junction diode emitting violet-blue-green-red light when activated using a current injection. The LED lamp relies on spontaneous emission of light. LED based white lamps have been developed based on groups III-V semiconductor materials, including GaN, InGaN, GaAs, and InP. LED lamps are now used in replacing conventional incandescent lamps and fluorescent lamps in general illumination, traffic signals, indoor lighting and street lighting.
However, the LED lamps are facing one common issue, namely the “efficiency droop,” where their power conversion efficiency reaches a peak at relative low-power density and then, rapidly drops when the operation power increases. In other words, the LED based lamp will suffer from low-efficiency for high brightness applications when the LEDs are driven by high electrical power.
As the illumination devices are facing the problems noted above, there is a similar situation in the wireless data communication industry, where a high demand of data exchanging capabilities is required, i.e., it is important to enable Internet access, live video streaming, and Internet of things (IOT) applications to many locations where it may be difficult install wireless communication capabilities. Currently, radio frequency (RF) based wireless communication technologies have been widely used. Those include Bluetooth, WiFi, wlan, cellular network, and they cover both indoor and outdoor applications. However, the RF-based wireless communications have drawbacks such as the electromagnetic interference (EMI) and security concerns. The EMI limits the RF wireless communication usage in airplanes, hospitals and other areas that are sensitive to such RF signal interference.
This is so because the RF signal usually emits in all directions and can easily transmit through walls, which is undesirable for applications requiring strong directionality and confining the signal to control the potential information leakage. Visible light communication (VLC) using LEDs has recently been proposed to address those concerns. Data communication by encoding the modulation signal in the white light bulb and detection of the data using a photodetector has been proposed and is known as Li-Fi technology. Such technology enables the illumination and data communication to take place in a same device using the same LED as the emitter. However, owing to the spontaneous emission nature of the LED lamp, the modulation bandwidth of the LED communication is limited to less than 100 MHz.
Various devices been tried to be used for both illumination and wireless data communication are now briefly discussed. U.S. Pat. No. 5,535,230, entitled “Illuminating light source device using semiconductor laser element” discloses an illuminating light source device suitable for illumination at a vibrating place or a portion where an electric lamp is hardly exchangeable for a new one. The illuminating light source device includes a semiconductor laser element for outputting a laser beam of a particular wavelength in the range from infrared rays to ultraviolet rays, a lens for diffusing the laser beam from the semiconductor laser element, and a fluorophore for converting the diffused laser beam from the diffusion lens into visible light. The illuminating light source device includes a group of semiconductor laser elements for respectively outputting laser beams of three primary colors consisting of red, green and blue, a lens for diffusing the laser beam from each of the semiconductor laser elements, and lenses for superposing the diffused laser beams from the diffusion lenses. Mercury atoms or rare earth substances are doped into the active layer of the semiconductor laser element and a second harmonic generation medium is provided on the output side of the semiconductor laser element. However, using mercury atoms poses a danger to the environment and it is undesirable.
U.S. Pat. No. 7,959,312 B2 entitled “White light emitting device and white light source module using the same” describes a white light emitting device including: a blue light emitting diode chip having a dominant wavelength of 443 to 455 nm; a red phosphor disposed around the blue light emitting diode chip, the red phosphor excited by the blue light emitting diode chip to emit red light; and a green phosphor disposed around the blue light emitting diode chip, the green phosphor excited by the blue light emitting diode chip to emit green light. Further, this reference discloses that a white LED is used and includes a resin encapsulant encapsulating the blue light emitting diode chip, where the green phosphor and the red phosphor are dispersed in the resin encapsulant. However, the efficiency of this device is limited by the efficiency droop discussed above.
U.S. Pat. No. 8,851,694 B2 entitled “Semiconductor light source apparatus” describes a semiconductor light source apparatus that includes a clad layer, a phosphor layer surrounded by the clad layer and a laser diode emitting a laser light. The phosphor layer can include a cavity having an opening for receiving the laser light, a phosphor material and a light-emitting surface of the apparatus. The laser light entering into the cavity can repeatedly reflect on an inner surface of the phosphor layer, each and every time most of the laser light entering into the phosphor layer. The laser light can be efficiently wavelength-converted by the phosphor material and the wavelength converted light can be emitted from the light-emitting surface having various shapes exposed from the clad layer. This reference also discloses guiding the light into a closed cavity or confined in a conical shape with sidewall coated with phosphors, which is difficult to implement in a practical device.
U.S. Patent Application Publication No. 2012/0106178 A1 entitled “Light emitting device, vehicle headlamp, illumination device, and laser element” describes a light-emitting section for generating fluorescence by receiving a laser beam, and a light irradiation unit for irradiating a light irradiated surface of the light emitting section with a laser beam that increases regularly in beam diameter in a direction in which the laser beam travels. The reference also discloses a light emitting device that includes one or more excitation light sources for emitting an excitation light with one concave mirror for converging the excitation light and a light emitting section for emitting fluorescence by receiving the excitation light converged by the concave mirror. However, implementing in a practical application a concave mirror and controlling the shape of the laser beam with such a mirror is cumbersome.
U.S. Patent Application Publication no. 2017/0051883 A1 entitled “Specialized integrated light source using a laser diode” describes an integrated white light source that includes a laser diode, a phosphor, a common support member to support the laser diode device and the phosphor member, a heat sink, a submount member, an output facet, a free space within a vicinity of the common support member with a non-guided characteristic capable of transmitting the laser beam from the laser diode to the phosphor member, an angle of incidence configured between the laser beam and the phosphor member, a transmissive mode characterizing the phosphor such that the laser beam is incident on an excitation surface of the phosphor member, a white light emitted from at least one emission surface of the phosphor member, and a form factor characterizing the integrated white light source.
All these devices either use elements that pose a danger to the environment, or use complicated designs that are difficult to be practically implemented in a commercial product. Therefore, there is a need to develop a better illuminating light source that is not only better at generating light for illuminating the surrounding, but also it is better in terms of data transmitting capabilities, i.e., having a better bandwidth and higher-speed.
According to an embodiment, there is an illuminating and wireless communication device that includes a base, a shell attached to the base and forming a closed chamber, a laser diode located inside the closed chamber and configured to generate visible light, and a photodetector located inside the closed chamber and configured to detect incoming light. A parameter of the generated visible light is modulated to encode information.
According to another embodiment, there is a method for illuminating and wireless communication, and the method includes providing an illuminating and wireless communication element, modulating an electrical current supplied to the illuminating and wireless communication element, generating modulated visible light with a laser diode, based on the modulated electrical current, and detecting incoming modulated light with a photodetector. The laser diode and the photodetector are attached to a base that is covered with a shell.
For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
The following description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following embodiments are discussed, for simplicity, with regard to the terminology and structure of a laser light apparatus with wireless communication transmitter function that can be used indoor for illumination and wireless communication. However, the embodiments to be discussed next are not limited to a configuration that can be used for indoor only, but may be used with other configurations, for example, outdoor illumination, etc.
Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.
An illuminating and wireless communication device 100 is illustrated in
Returning to
A mounting mechanism 140 is also attached to the base 102 and configured to support the laser diode 110 and the photodetector 120. The mounting mechanism 140 may include two units 142 and 144 that surround the single package 104. In one embodiment, the two units 142 and 144 are formed as a unitary body that has a cavity 146, in which the single package 104 is placed.
A shell 150 is attached to the base 102 in such a way that the shell 150 and the base 102 define a closed chamber 152, in which the single package 104 and the mounting mechanism 140 are located. In one embodiment, the shell 150 is directly attached to the base 102 and the chamber 152 is completely sealed from the ambient. The chamber 152 may be filled with a filing material 154, which may be air, a noble gas, a gel or a solid material that are good heat conductors to conduct away the heat generated by the laser diode 110 and have a refractive index matching the refractive index of the material of the laser diode. At the same time, the filing material has to have good optical properties, i.e., to allow the light 162 emitted by the laser diode 110 to propagate to the shell 150 with minimum loss and deviation, and at the same time, to allow an incoming light 164 to arrive to the photodetector 120 with minimum loss. The filing material 154 needs to be an electrical insulator so that it will not generate a short circuit during the operation of the laser diode and the photodetector. In one application, the shell 150 does not touch the single package 104 or the mounting mechanism 140. The shell 150 may have a semi-spherical shape as shown in
The shell 150 may include a diffuser layer 156 that is made of a light transparent material. The material of the diffuser layer 156 is selected to be a material that diffuses or scatters light in some manner to transmit soft light. Diffused light can be obtained by reflecting light from a white surface, while more compact diffusers may use translucent material, including ground glass, teflon, holographs, opal glass, and greyed glass. The purpose of the diffuser layer 156 is to make the emitted light 160 appropriate for illumination purposes.
The diffuser layer 156 is covered with a solid color converter layer 158. The color converter layer 158 may include a solid material that is coating the diffuser layer 156. The color converter layer 158 is configured to change the blue or violet light 162 emitted by the laser diode 110 to white light, which is desired for illumination purposes. Note that in one embodiment, the laser diode 110 is a side emitting semiconductor device. In one embodiment, the shell may include, in addition to the diffuser layer, micro-gratings, blue phosphor, green phosphor, yellow phosphor, red phosphor, surface roughening layer, anti-reflection layer, or a combination of them.
The embodiments illustrated in
The device 100 shown in
The data input of the signal generator/FPGA circuit might be originated from data generating device 420, for example, a server, a computer, a laptop, a cell phone, or any device that might generate data. The data exchange between the data generating device 420 and the data processing device 410 may be implemented in a wired or wireless manner. If implemented in a wired manner, the data processing device 410 is connected to a port 414 (e.g., USB, Ethernet, etc.). If implemented in a wireless manner, the data processing device 410 may include a transceiver 416 for communicating with the data generating device 420.
The data received from the data generating device 420 is then encoded by the data processing device 410 and transmitted with the laser diode 110. In one application, the intensity of the light emitted by the laser diode 110 is modulated with the signal from the data processing device to transmit the data in a wireless manner. Thus, the data processing device 410 may be in communication with a global controller 430, also located on the circuit board 402, and the global controller 430 controls the electrical power supplied to the laser diode 110 for modulating the emitted light 162. Other parameters of the light (for example frequency or phase) may be modulated for transmitting the data.
To receive data, modulated light 164 generated by a user 440 is received by the photodetector 120, through the shell 150, for each element 100 (if more than one element 100 is present). The resulting signal is sent to the data processing device 410 for demodulation and then the demodulated data may sent to the data generating device 420. Note that the data generating device 420 may be part of a data provider entity, and may be connected to the Internet through other means so that a user's device 440 (e.g., computer, cell phone, etc.) is capable to fully connect to the internet through the laser light power bank device 400 and the data generating device 420.
Different from the embodiment of
About the shell 150 used in the previous embodiments, it is noted that it can be shaped to be dome-shaped or other shapes, and it may be made of ceramic, crystal, plastic or other compound materials that is used to cover the laser diode. The dome-shape shell may contain two or more layers (as shown in
The structure of the shell 150 may be implemented, as illustrated in
The element 100 of
The element 100 may be used not only for indoor purposes (illumination and wireless communication), but also for outdoor purposes, for example, vehicle headlights that are used to communicate in a wireless manner with surrounding vehicles (e.g., cars, airplanes, drones, boats, etc.) for collision avoidance, headlight for underground mining, diving, torch light, etc. In this regard, the elements discussed above are configured to simultaneously perform the functions of light generation and data communication while also being able to illuminate a given area without performing data communication.
A method for illuminating and wireless communication with the element 100 is now discussed with regard to
The method may further include a step of changing with a color converter layer a wavelength of the generated light to obtain white light, wherein the color converter layer is part of the shell, and/or a step of diffusing the white light with a diffuser layer, wherein the diffuser layer is part of the shell, and/or a step of measuring with a temperature sensor, which is placed inside the closed chamber, a temperature of the laser diode.
The disclosed embodiments provide a device that is capable to illuminate its surroundings with white light and also to achieve wireless communication of data through the same white light. It should be understood that this description is not intended to limit the invention. On the contrary, the exemplary embodiments are intended to cover alternatives, modifications and equivalents, which are included in the spirit and scope of the invention as defined by the appended claims. Further, in the detailed description of the exemplary embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details.
Although the features and elements of the present embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein.
This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims.
This application claims priority to U.S. Provisional Patent Application No. 62/703,592, filed on Jul. 26, 2018, entitled “AN APPARATUS OF ILLUMINATING AND WIRELESS COMMUNICATION TRANSMITTER USING VISIBLE LASER DIODES,” the disclosure of which is incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2019/055843 | 7/9/2019 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62703592 | Jul 2018 | US |
