The invention generally relates to luminaires. More particularly but not exclusively, this invention relates to packaging of an outdoor luminaire mounted microphone for achieving waterproof and minimized unwanted noise performance.
Outdoor luminaires have begun to be pressed into service as power and mounting platforms for a variety of electronic sensor and data processing systems. The sensors used in these systems can be one or more from a wide variety including, but not limited to, cameras, microphones, environmental gas sensors, accelerometers, gyroscopes, antennas, and many others.
Due to the nature of outdoor placement, exposure to a variety of weather conditions must be considered when contemplating the construction of such a system. A variety of traditional sealing and weatherproofing methods exist for the creation of a housing that can contain the electronics portion of the system, and standard methods exist for means to protect optical elements, such as protective windows and performance enhancement coatings for use with cameras and lenses. A special case exists when considering the means to package a microphone for use on such an outdoor luminaire platform, as further described herein.
According to a first aspect of the invention, an outdoor luminaire, comprising: an exterior housing comprising a wall being waterproof and comprising one or more holes, where each of the one or more holes is covered on an interior surface of the wall with a membrane, e.g., comprising polytetrafluoroethylene (ePTFE), using a waterproof seal, wherein the membrane is waterproof and impervious to ultraviolet radiation but substantially transparent to sound waves; one or more microphones, each located in a vicinity of a corresponding hole of the one or more holes and configured to receive a corresponding sound wave signal through the corresponding hole; and a foam material (e.g., low density foam material) surrounding the each of the one or more microphones (i.e., mounted inside of the foam material) to mechanically de-couple the each microphone from the exterior housing to protect the each microphone from detecting unwanted outside noises (which may include one or more of: an impact noise of falling rain drops, sleet or hail), wherein an exterior surface of the wall including each hole and all parts of corresponding one or more areas surrounding each of the one or more microphones are unobtrusive into an exterior air column surrounding the exterior surface of the wall in order to reduce creation of a wind noise which is detectable by at least one of the one or more microphones.
According further to the first aspect of the invention, the each of the one or more microphones may be separated from the membrane by a predefined distance, which can be provided by a spacer also made from a foam material.
According to a second aspect of the invention, a sensor module attachable to and detachable from an outdoor luminaire, the sensor module comprising: an exterior housing comprising a wall being waterproof and comprising one or more holes, where each of the one or more holes is covered on an interior surface of the wall with a membrane, e.g., comprising polytetrafluoroethylene (ePTFE), using a waterproof seal, wherein the membrane is waterproof and impervious to ultraviolet radiation but substantially transparent to sound waves; one or more microphones, each located in a vicinity of a corresponding hole of the one or more holes and configured to receive a corresponding sound wave signal through the corresponding hole; and a foam material (e.g., low density foam material) surrounding the each of the one or more microphones (i.e., mounted inside of the foam material) to mechanically de-couple the each microphone from the exterior housing to protect the each microphone from detecting unwanted outside noises (which may include one or more of: an impact noise of falling rain drops, sleet or hail), wherein an exterior surface of the wall including each hole and all parts of corresponding one or more areas surrounding each of the one or more microphones are unobtrusive into an exterior air column surrounding the exterior surface of the wall in order to reduce creation of a wind noise which is detectable by at least one of the one or more microphones.
According further to the second aspect of the invention, the each of the one or more microphones may be separated from the membrane by a predefined distance, which can be provided by a spacer also made from a foam material.
These and other features and aspects of the present disclosure will become better understood when the following detailed description is read, with reference to the accompanying drawings, in which like characters represent like parts throughout the drawings, wherein:
New packaging is presented for integrating a microphone into an outdoor luminaire that provides high sensitivity and dynamic range together with being waterproof, resistant to impact and wind noise, environmentally resistant and unobtrusive to passers-by. Various embodiments describe packaging of outdoor luminaire mounted microphones to achieve waterproof and minimized unwanted noise performance, and other desirable features.
For use with an outdoor luminaire, and by virtue of its high position relative to the street, as well as due to outdoor environmental requirements, a microphone needs to be able to have the following characteristics (referred to as a “List of Requirements” in this document):
The various embodiment of the invention described herein provide a solution for mounting a microphone into an outdoor luminaire and simultaneously meeting all of the desired characteristics above, namely being waterproof, having good dynamic range and sensitivity, having high impact noise resistance, wind noise resistance, unobtrusiveness and environmental resistance.
In different embodiments, a material known to manufacturers of outdoor luminaires as GORE-TEX vents, can be used. GORE-TEX vents have a desirable property such that gases can pass easily through their extremely small pore expanded polytetrafluoroethylene (ePTFE) structure, while not allowing liquids to pass through due to their high relative surface tension. Also the ePTFE material is a UV resistant material. Traditionally, GORE-TEX vents have been used to allow the luminaire to “breathe” between the interior of the housing and outside environment. This gas permeability, together with the non-rigid structure of GORE-TEX ePTFE material, makes it an ideal material for shielding a microphone. Sound waves may be able to pass through the Gore-Tex vent with very little loss in acoustic energy, while liquids are prevented from doing so. The non-rigid structure of the ePTFE material typically does not reverberate and does not modally respond to in-band acoustic energy.
The expanded PTFE can be a mechanically processed form of PTFE (also known as TEFLON) that gives it a porous structure with pore sizes large enough to let gases pass through, but small enough that the surface tension of liquid water cannot pass. It is possible that other open or closed cell materials may be also used, including any type of sheet membrane comprising materials like plastic, polycarbonate, and the like that can also be described as being UV resistant in order to meet the weathering requirement.
Moreover, in order to make the microphone less susceptible to impact noises, it may be necessary to mechanically decouple the microphone from any part which can easily conduct noise from the exterior housing. The impact of falling rain drops, sleet and hail can generate significant conducted and ringing noise within the structure, and any component which is tightly mechanically coupled to it can sense this noise. By utilizing a sufficient layer of a foam material such as low density foam material between the microphone and the housing according to an embodiment of the invention, this conducted noise can be greatly reduced or eliminated altogether.
Furthermore, in order to make the microphone less susceptible to wind noise, it is desirable to have the outer housing of the structure and any portion surrounding the microphone to be as smooth as possible. The housing can be made from aluminum, but can also be made from other metals or rigid materials such as plastic.
By mounting the microphone behind a small hole in the structure, it can easily sense the acoustic pressure waves which it is intended to detect. By thinning out the material on the interior or exterior surface annularly surrounding the hole, the GORE-TEX membrane can be adhesively bonded to the interior surface and restore the outer surface to a nearly smooth construction. It can be further improved by tapering the edges of the hole so that the housing and interior mounted GORE-TEX membrane meet at a “knife edge”, which can further serve to make a smooth exterior so as to avoid the creation of turbulence which can, in turn, generate noise by virtue of its rapidly changing pressure component. Traditional means for shielding against wind noise include the use of windscreens made from faux fur or low density foam, but neither of these materials would function well for long duration exposure to the elements, and would also serve to make the microphone more noticeable to passers-by.
Thus, according to one embodiment of the invention, in order to meet the List of Requirements, an outdoor luminaire can comprise: an exterior housing comprising a wall being waterproof and comprising one or more holes, where each of the one or more holes is covered on an interior surface of the wall with a membrane using a waterproof seal, wherein the membrane is waterproof and impervious to ultraviolent radiation but substantially transparent to sound waves; one or more microphones, each located in a vicinity of a corresponding hole of the one or more holes and configured to receive corresponding sound wave signal through the corresponding hole; and a foam material (such as low density foam material) surrounding the each of the one or more microphone to mechanically de-couple the each microphone from the exterior housing to protect the each microphone from detecting outside noises (which can include, e.g., one or more of: an impact noise of falling rain drops, sleet or hail), wherein an exterior surface of the wall including each hole and all parts of corresponding one or more areas surrounding each of the one or more microphones are unobtrusive into the exterior air column surrounding the surface of the wall in order to reduce the opportunity to create wind noise which may otherwise be detected by any of the one or more microphones.
According to further embodiments, each of the one or more microphones may be mounted inside of the low density foam. Also, each of the one or more microphones may be separated from the membrane (the membrane can be comprised of ePTFE) by a predefined distance for optimum detection, wherein the distance is such that the aperture of the microphone is held closely to the exterior wall, but not far enough away so that it attenuates the sound pressure detection. This is often determined empirically as a function of the various frequencies of the sounds to be preferentially detected. The predefined distance can be provided/defined (optionally) using a spacer, which can comprise a foam material (e.g., low density material). Still further according to various embodiments, the membrane can be configured to minimize reflected sound waves to avoid reverberation. Also, a presence of the one or more microphones can be provided to be non-obstructive to passers-by (see
Figures presented below provide non-limiting examples for practicing various embodiments of the invention. It is noted that identical or similar parts/elements are designated using the same reference numbers in different figures.
Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one having ordinary skill in the art to which this disclosure belongs. The terms “first”, “second”, and the like, as used herein, do not denote any order, quantity, or importance, but rather are employed to distinguish one element from another. Also, the terms “a” and “an” do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. The use of “including,” “comprising” or “having” and variations thereof herein are meant to encompass the items listed thereafter and equivalents thereof, as well as additional items. The terms “connected” and “coupled” are not restricted to physical or mechanical connections or couplings, and can include electrical and optical connections or couplings, whether direct or indirect.
Furthermore, the skilled artisan will recognize the interchangeability of various features from different embodiments. The various features described, as well as other known equivalents for each feature, can be mixed and matched by one of ordinary skill in this art, to construct additional systems and techniques in accordance with principles of this disclosure.
In describing alternate embodiments of the apparatus claimed, specific terminology is employed for the sake of clarity. The invention, however, is not intended to be limited to the specific terminology so selected. Thus, it is to be understood that each specific element includes all technical equivalents that operate in a similar manner to accomplish similar functions.
It is to be understood that the foregoing description is intended to illustrate and not to limit the scope of the invention, which is defined by the scope of the appended claims. Other embodiments are within the scope of the following claims.
It is noted that various non-limiting embodiments described and claimed herein may be used separately, combined or selectively combined for specific applications.
Further, some of the various features of the above non-limiting embodiments may be used to advantage, without the corresponding use of other described features. The foregoing description should therefore be considered as merely illustrative of the principles, teachings and exemplary embodiments of this invention, and not in limitation thereof.
Number | Date | Country | |
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62349485 | Jun 2016 | US |