ENVIRONMENTAL SHROUD

Abstract: The invention provides an environmental shroud (490, 590) and a camera assembly (40, 50) including such environmental shroud (490, 590) which absorbs and dissipates heat energy that is not reflected and/or deflected from radiation and heat energy that is generated by the contents of the camera housing so that the camera housing temperature does not exceed the maximum rated temperature. In one embodiment, the camera assembly (40) includes a camera housing (430) which has a mounting cap (440) attached to sidewalls (426) to which is attached an optical surface (135). The camera housing encloses a camera system. An environmental shroud (490) is attached to the camera housing and includes a plurality of vertical strips (441, 445) situated concentrically with the camera housing (430) and with each other with gaps being present between the vertical strips (441, 445) and between the camera housing (430). In another embodiment, the environmental shroud is a turbine and includes a plurality of vertical blades (506) situated concentrically with the camera housing (530), whereby wind which contacts the blades causes the shroud to rotate and generate a centrifugal force effective to remove moisture from the camera housing (530).

Description: Environmental shroud. FIELD OF THE INVENTION This invention relates to an environmental shroud that may be used in indoor/outdoor surveillance equipment and systems, and more particularly, to an improved camera assembly which has a housing that includes an environmental shroud. BACKGROUND OF THE INVENTION Closed-circuit surveillance equipment is well established and can include fixed-position cameras and zoom lenses mounted on pan and tilt mechanisms which are typically controlled by security personnel. In outdoor locations, an enclosure for the camera housing is usually employed and domed housing for such cameras are desirable due to their appearance as well as the fact that the camera itself is not easily visible, though the camera can scan a wide area. In a typical outdoor camera enclosure, a single main housing part is utilized, wherein a top thereof is connected to a pipe. Electrical connections are generally routed from a main power source through the pipe and into the housing. In addition, a hemispheric dome and additional internal components, such as the camera power supply, camera body, lens, pan & tilt mechanism, and controller electronics, are removably attached to an inside of the single housing part. Such camera assemblies are subject to damage and require means to protect the camera from moisture and precipitation, extremes in temperature, and unauthorized tampering. For example, some conventional housings permit rain water or other moisture to accumulate and run down the conical side of the housing and onto the dome itself. Another concern is with the heat caused by sunlight or generated in the housing during use of the camera and the need to deflect such heat energy and /or to dissipate the same from the camera housing to prevent damage thereto. Prior attempts to address some of these problems include U.S. Patent No. 4,320,949 which, for example, in one embodiment provides a housing with a cover with a skirt over which rainwater may flow, form pendant drops, and fall, and a camera mount adapted to carry a camera and a camera positioning motor. A dome unidirectionally transparent to light is secured to the cover. The cover and dome form an air space between them. A fan is disposed in a side wall of the upper support housing to provide forced cool air circulation in the housing to cool the housing when the temperature reaches a certain predetermined level. The assembly also includes heaters which are operated when the temperature in the housing approaches freezing. In a second embodiment, air is brought into the assembly by natural circulation, i.e. a space or inlet area is provided at the interface of the support housing and cover member so that air can naturally enter the support housing about the circumference of the housing. This air is circulated downwardly adjacent the inner wall of the cover member and then up into the support housing where it is exhausted through an air exhaust port. In U.S. Patent 5,689,304, commonly assigned herewith, there is disclosed a surveillance housing assembly which comprises an outer shell having a top wall portion and side wall portion, wherein the side wall portion extends in a downward direction from the top wall portion to thereby define a first cavity. An inner shell comprises a top wall portion for mounting engagement with an underside of the top wall portion of the outer shell within the first cavity. The inner shell further comprises a top wall portion and a side wall portion, wherein the side wall portion extends in a downward direction from the top wall portion to thereby define a second cavity. The top wall portion 18 of the outer shell 12 has an exhaust aperture 32 positioned off-center from a central axis 34 of the outer shell; a generally circular aperture 36 is centered on the central axis and is provided in the top wall portion 18 to enable cable to pass through; and the top wall portion 22 of the inner shell 14 has an air exhaust aperture designed to be coincident with the air exhaust aperture 32 of the top wall portion 18 of the outer shell 12; and still further, the top wall portion 22 of the inner shell 14 has a generally circular aperture which is coincident with the aperture 36. Air inlet apertures 44 define an air flow to exhaust 32. The housing also has a decorative cap 70 which has a plurality of notches along its bottom edge which, cooperate with other parts to provide a path for an exhaust air flow and provides for protection against an ingress of unwanted water. This assembly also comprises various combinations of heaters and blowers. Further in this arrangement, a sequence of wall surfaces and plateau surfaces are arranged for securing components of the surveillance equipment thereto in a prescribed manner such that first components of the surveillance equipment are disposed in between the underside of the outer shell and an outerside of the inner shell, and second components of the surveillance equipment are disposed within the second cavity. While air circulation via fans and exhaust ports and/or air-intake valves and air-exhaust valves is satisfactory to compensate for environmental temperature changes in some surveillance systems, it has its limitations, most notably in terms of added cost and complexity, size and power constraints occasioned by the need to incorporate such components into the surveillance assembly. There remains a need in the art for a camera surveillance system which does not suffer from the disadvantages set forth above and which provides protection to the camera from moisture and heat without imposing undesirable size and power constraints. SUMMARY OF THE INVENTION An object of the invention is to provide (a camera housing with) an improved environmental shroud. To this end , the invention provides camera housings and shrouds as defined in the independent claims. The dependent claims define advantageous embodiments. In one embodiment, the shroud is designed to deflect or reflect the radiant heat energy generated by the sun or any other heat source so that the heat does not penetrate the camera housing. An object of an embodiment of the invention is to provide a camera housing having an environmental shroud which absorbs and dissipates heat energy that is not reflected from radiation and heat energy that is generated by the contents of the camera housing so that the camera housing temperature does not exceed the maximum rated temperature. An object of an embodiment is to provide such an environmental shroud which protects the camera housing from rain or any other type of moisture by providing a tortuous path for which prevents water penetration inside the environmental shroud. Another object of an embodiment of the invention is to provide an environmental shroud having a "drip edge" so that the water has a means of falling off the environmental shroud to avoid obstructing the optical surface of the camera housing. A preferred embodiment of the invention is formed by a camera assembly having a housing which comprises an environmental shroud having a configuration which reflects and/or deflects heat energy, dissipates heat energy not reflected and/or deflected, protects the camera from water or other moisture, and enables a high level of heat dissipation even when the camera is operated in sunlight at high ambient temperature. Preferably, the environmental shroud includes a coating to deflect the heat energy and a vent to dissipate the heat energy. In the most preferred embodiments, the shroud also includes a drip edge for water or moisture to run off of the camera housing. WO 01/04855 * PCT7EP0O/O6329 These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 A shows an external view of a fourth embodiment of a camera assembly of this invention; Fig. IB is a bottom view of the embodiment of Fig. 1 A; Fig. 1C is vertical offset cross-section of the embodiment of Fig. IB taken along the line C-C; Fig. ID is a sectional view taken along line F-F of Fig. 1 A; Fig. IE is a sectional view of an alternative embodiment of the invention illustrated in Fig. 1A; Fig. 2 A is a vertical cross-section of a fifth embodiment of the a camera assembly of this invention; and Fig. 2B is a top cross-section of the embodiment illustrated in Fig. 2 A. With reference to Figures 1 and 2, the embodiments illustrated therein do not present a largely smooth surface appearance. This is to promote enhanced convection heat transfer from a larger portion of the surface of the housing than is obtained by the natural convection to produce a lower internal housing temperature at the maximum ambient temperature. These embodiments also avoid a large cavity in which insects or other pests might be likely to take up residence. Secondly, these embodiments are of modular construction which allows for smaller tooling and part shipping volume prior to assembly. As will be seen, the overall outer profile need not be a "bell" or domed shape and allows for a the multi-piece construction that "wraps" around the housing to give design appearance alternatives. Thirdly, since convection plays a larger heat transfer role than conduction, the various parts of these embodiments may preferably be constructed of weather-resistant non- metallic materials, resulting in considerable cost savings. With reference to Fig. 1, there is illustrated a modified aero-foil environmental shroud 490, which has no moving parts. As illustrated in Figs. 1 A and IB, a camera assembly 40 has a camera housing 430 having a mounting cap 440 attached to sidewalls 426 which are attached to an optical surface 135. As best seen in Figs. IB and ID, two rings of vertical strips 441 and 445 are placed concentric with the housing 430. The inner ring of strips 441 is placed at some distance from the housing 430, and the outer ring of strips 445 at some distance from the inner ring of strips 441, such that air can circulate between all three, i.e. in the gaps between 430, 441 and 445. The inner strips 441 are positioned at the gaps (x) between the outer strips 445 so an air stream 413 traveling to the housing surface 430 must turn and flow tangentially for some distance after radially entering the outer gap (x). Therefore precipitation moisture entering radially through the outer gap (x) will strike the inner strips 441 and drain downward without reaching the camera housing 430 or the optical dome surface 135. The strips 441 and 445 are secured at top and bottom by structural cap 407, 408 and ring 409, 410 parts such that they maintain their relative alignment. In addition, the mounting cap piece 440 mates with the camera housing 430 to prevent water ingress at the top of the environmental shield 490. In one embodiment, the external vertical strips 445 are partial cylinder shapes attached to the inside lip of a circular top cap 407 such that the overall shape is cylindrical. The internal vertical strips 441 are also attached to the lip of another smaller circular cap 408 attached underneath the larger cap. As illustrated in Fig. IE, the internal strips 441 preferably have a central outfacing vertical ridge profile 411 to direct the air stream behind the external strips when wind impinges normal to the outer gap, and set up a circulating venturi effect when the wind impinges normal to the center of the external strip 445. In a variation thereof, outwardly facing radial edges 412 on both sides of the inner strips 441 are turned to further prevent precipitation from blowing into contact with the camera housing 430. Fig. 2 illustrates an embodiment of the invention in which the camera assembly 50 comprises an environmental shroud 590 which is a modified turbine with moving parts. The shroud includes a bearing 507 which is centrally positioned at the top of the camera housing 530. This bearing is large enough to permit camera power supply, video, and control wires (not shown) to pass through the center bore. In the case of a ball bearing, the center race is firmly attached to the camera housing 530. An example of a turbine blade assembly 505 is illustrated in Fig. 2B. The turbine blades 506 are attached firmly to the outer race of the bearing 507 and is coupled to the camera housing 503 and the mounting cap 540 via a coupling plate 504, thus forming a structure that protects the bearing from the elements and prevents water ingress at the top. The turbine blades 506 consist of strips of metal that are formed into arcs and overlapped at an angle to the radial direction such that they form vanes to catch the wind and rotate the turbine irregardless of the wind direction. Any wind threatening to force precipitation into the gaps between blades will also rotate the assembly, generating centrifugal force to push the moisture away from the interior. When no breeze is blowing, the gaps between the blades provide significant area for natural convection. When a breeze is blowing, the stirring action of the turbine blades will promote forced convection at the camera housing surface, further increasing heat transfer. In addition, as a result of this construction, heat transfer conditions around the entire housing are very uniform. The sun shining from one direction will not heat just one side, but the heat will be distributed evenly. In an alternative embodiment thereof, a continuous ridge or depression running down the center of the blade is added to channel moisture down to the bottom where a taper is provided for a drip edge 508. A ring may be attached at the bottom circumference to provide structural support and is also configured to facilitate the movement of moisture away from the camera housing window 135. The aesthetic appearance of the moving turbine blades can be modified as desired. For example, strips similar to those illustrated in the Fig 1 embodiment may be attached over the blades to minimize this effect. In this instance, with no wind, the area available for natural convection is somewhat decreased and when the breeze is blowing, less energy will reach the vanes to turn the turbine assembly. However, the blades will be protected from damage and will be effective to remove heat and protect the camera housing as contemplated herein. It is also contemplated that other combinations of the Fig.1 and Fig.2 embodiments may be realized. For example, inner and outer vertical strips may be employed to partially or completely cover the turbine blades. While the invention has been described for convenience in the context of an environmental shroud for a camera assembly, and particularly when used to protect outdoor surveillance cameras, it will be understood that the invention is not limited to these embodiments. The environmental shrouds of the invention may be used in any context where it is necessary to protect the contents of a housing from moisture and heat, for example enclosed lighting, electronic equipment, other surveillance equipment such as switches, multiplexers, etc. Additionally, the invention may be embodied in other specific forms without departing from the scope or essential characteristics thereof, the present disclosed examples being only preferred embodiments thereof. It should thus be noted that the above- mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps other than those listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means can be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims: CLAIMS: 1. A camera assembly (40) which comprises: a camera housing (430) having a mounting cap (440) attached to sidewalls (426) to which is attached an optical surface (135), the camera housing enclosing a camera system; and an environmental shroud (490) attached to the camera housing and effective to reflect and/or deflect heat energy, dissipate heat energy not reflected or deflected, and protect the camera housing from the ingress of moisture, wherein said shroud comprises a plurality of vertical strips (441,445) situated concentrically with the camera housing (430) and with each other, gaps being present between the vertical strips (441,445) and between the camera housing (430). 2. A camera assembly as claimed in Claim 1 , wherein said strips comprise an inner ring of strips (441) and an outer ring of strips (445) and wherein the inner ring of strips (441) is located at a predetermined distance from the camera housing (430), and the outer ring of strips (445) is located at a predetermined distance from the inner ring of strips (441), and wherein air convection circulates in the gaps present between the strips and the camera housing. 3. A camera assembly as claimed in Claim 2, wherein the inner strips (441) are positioned at gaps (x) between the outer strips (445). 4. A camera assembly as claimed in Claim 2, wherein the strips (441) and (445) are secured at top and bottom by structural cap (407,408) and ring (409, 410) parts such that they maintain their relative alignment. 5. A camera assembly as claimed in Claim 4, wherein the structural cap piece (440) mates with the camera housing (430) to prevent water ingress at the top of the environmental shroud. 6. A camera assembly as claimed in Claim 5, wherein the outer vertical strips (445) are partial cylinder shapes attached to the inside lip of a circular top cap (407) such that the overall shape is cylindrical. 7. A camera assembly as claimed in Claim 6, wherein the inner vertical strips (441) are also attached to the lip of a smaller circular cap (408) attached underneath the circular top cap (407). 8. A camera assembly as claimed in Claim 2, wherein the inner strips (441) have a central out-facing vertical ridge profile (411) to direct the air stream behind the outer strips (445) when wind impinges normal to the gap (x), and set up a circulating venturi effect when the wind impinges normal to the center of the outer strip (445). 9. A camera assembly as claimed in Claim 2, wherein outwardly facing radial edges (412) on both sides of the inner strips (441) are turned to further prevent precipitation from blowing into contact with the camera housing (430). 10. A camera assembly (50) which comprises: a camera housing (530) having a mounting cap (540) attached to a top wall which includes a connecting device (504) and a bearing (507), and sidewalls (526) to which is attached an optical surface (135), the camera housing enclosing a camera system; and an environmental shroud (590) attached to the camera housing and effective to reflect and/or deflect heat energy, dissipate heat energy not reflected or deflected, and protect the camera housing from the ingress of moisture, wherein said shroud is a turbine and comprises a plurality of vertical blades (506) situated concentrically with the camera housing (530), gaps being present at least between selected vertical blades (506), whereby wind which contacts the blades causes the shroud to rotate and generate a centrifugal force effective to remove moisture from the camera housing (530). 1 1. A camera assembly as claimed in Claim 10, wherein said bearing (507) is centrally positioned at the top of the camera housing (530). 12. A camera assembly as claimed in Claim 11 , wherein the bearing is a ball bearing. 13. A camera assembly as claimed in Claim 12, wherein the bearing (507) has a plurality of attachment points to the outer race and center race attached to the camera housing (530). 14. A camera assembly as claimed in Claim 13, wherein the blades of the turbine (506) are attached to the outer race of the bearing. 15. A camera assembly as claimed in Claim 11, wherein the blades of the turbine (506) consist of strips of metal formed into arcs and overlapped at an angle to the radial direction such that they form vanes. 16. A camera assembly as claimed in Claim 15, wherein said vanes are effective to catch the wind and rotate the turbine irregardless of the wind direction. 17. A camera assembly as claimed in Claim 11 , wherein a ridge is present on a surface of at least multiple blades of the turbine and is effective to channel moisture down to a drip edge (508). 18. A camera assembly as claimed in Claim 11 , wherein a ring is attached at a bottom circumference of said turbine to provide structural support. 19. A camera assembly as claimed in Claim 18, wherein said ring is configured to facilitate the movement of moisture away from the camera housing (530). 20. An environmental shroud (490) attached to a housing (430) having a top portion (440) attached to sidewalls (426) to which is attached a bottom wall, said environmental shroud (490 being effective to reflect and/or deflect heat energy, dissipate heat energy not reflected or deflected, and protect the housing from the ingress of moisture, wherein said shroud comprises a plurality of vertical strips (441,445) situated concentrically with the housing (430) and with each other, gaps being present between the vertical strips (441,445) and between the camera housing (430). 21. An environmental shroud (590) attached to a housing (530) having a top wall, which includes a connecting device (504) and a bearing (507), attached to sidewalls (526) to which is attached a bottom wall, said environmental shroud (590) being effective to reflect and/or deflect heat energy, dissipate heat energy not reflected or deflected, and protect the housing from the ingress of moisture, wherein said shroud is a turbine and comprises a plurality of vertical blades (506) situated concentrically with the housing (530), whereby wind which contacts the blades causes the shroud to rotate and generate a centrifugal force effective to remove moisture from the housing (530).

Inventors: JONES THEODORE L, RYAN CHRISTOPHER J, JONES, THEODORE, L., RYAN, CHRISTOPHER, J.
Applicants: KONINKL PHILIPS ELECTRONICS NV, KONINKLIJKE PHILIPS ELECTRONICS N.V.
Application year: 2000
Main classification: G08B13
IPC codes: G03B15, G03B17, G08B13, G08B15, H04N5