ENVIRONMENTAL SHROUD

Abstract: The invention provides an environmental shroud (190) and a camera assembly (10) including the shroud. The environmental shroud (190) absorbs and dissipates heat energy that is not reflected 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 includes a camera housing (130) having a mounting cap (140) attached to sidewalls (126) to which is attached an optical surface (135), the camera housing enclosing a camera system; and an environmental shroud (190) attached to the camera housing . The shroud has a lower section (100) having sidewalls (126A) that descend to a drip edge (108), and at least one vent (105) in a top portion; and an upper section (120), at least the lower section having means that reflects or deflects radiant heat energy and means to remove unreflected or undeflected heat from the camera housing (130) through said vent (105), the upper section (120) covering the vent (105) and having a lower edge (125) situated below the vent and over the sidewalls (126A) to provide a tortuous path which prevents the penetration of water into the camera housing (130).

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. 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 first embodiment of a camera assembly of this invention; Fig. IB is a vertical cross-section of the embodiment illustrated in Fig. 1A taken along line A-A; Fig. 2A shows an external view of a second embodiment of a camera assembly of this invention; Fig. 2B is a vertical cross-section of the embodiment illustrated in Fig. 2A taken along line A-A; Fig. 2C is a bottom view of the embodiment of the invention illustrated in Figs. 2A and 2B; Fig. 2D is a top view of the embodiment illustrated in Fig. 2 A; Fig. 2E is a vertical cross-section similar to Fig. 2B and showing an alternative embodiment of the invention; Fig. 3 A shows an external view of a third embodiment of a camera assembly of this invention; Fig. 3B is a vertical cross-section of the embodiment illustrated in Fig. 3 A taken along line A-A; DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS With reference to Figs. 1 A and IB, there is illustrated a camera assembly 10 which comprises a mounting cap 140 attached to sidewalls 126 which are in turn attached to an optical surface 135 to form a camera housing 130 which surrounds a camera or lens assembly, not shown, all as is well known in the art. Attached to the camera housing 130 is an environmental shroud 190 which is effective to deflect heat energy, dissipate heat energy not reflected, protect the camera from water and/or other moisture, and enables a high level of heat dissipation even when the camera is operated in sunlight at high ambient temperature. According to a first embodiment of the invention illustrated in Fig. 1 A, a two-piece environmental shroud 190 surrounds the camera housing 130 substantially completely and comprises a lower section 100 and an upper section 120. The lower section 100 of the environmental shroud provides the protection from radiant heat energy for the camera housing 130 and may include a coating on a surface thereof or the surface itself may be specified so that the emissivity is such that it reflects or deflects most of the radiant heat energy from the sun or any other hot body. Suitable coatings may include polyester, polyurethane, epoxy, transparent metallized polycarbonate coatings, aluminum foil inside various transparent materials, galvanized steel, powder coatings, etc. The shroud also includes means to remove heat either absorbed from radiated heat energy or convected from the camera housing 130 through a vent 105 included in the top of the lower section 100. The upper section 120 of the environmental shield covers the vent 105 in the lower section 100. The lower edge 125 of the upper section is below the vent 105, thus providing a tortuous path that prevents water from penetrating and adhering to the camera housing 130. Instead the water is lead away from the housing via the environmental shroud to a drip edge 108 from which water, rain, melted snow, or other moisture will run off the environmental shroud. This configuration prevents water from adhering to the optical surface 135 and impairing optical performance. In a preferred version of this embodiment, a ridge or a valley 103 is formed in front of the vent 105 to further assist in preventing the egress of water or other moisture into the vent. This is particularly preferred when the difference in height between the lower edge 125 of the top portion 120 and the vent 105 is not great enough to establish a tortuous path which prevents water penetration of the camera housing 130. The embodiment of the invention illustrated in Figs. 3A and 3B is substantially the same as the Figure 1 embodiment described above except that it of a one- piece construction. Thus the environmental shroud embodiment of this figure achieves the same function as that achieved by the Fig. 1 A embodiment except that it is a one piece design. The single piece of the environmental shroud 390 prevents water from entering the cavity between the shroud and the camera housing, protects the camera housing from radiant heat energy, and provides a drip edge 308 to prevent water from running on to the optical surface 135. Louvres 305 are located on the sides near the top let the hot air escape and also provide protection from rain penetrating and adhering to the camera housing 330 and impairing the optical surface 135. In the embodiment of the invention illustrated in Figures 2 A, 2B, and 2C, the environmental shroud 290 achieves the same function as shroud 190 illustrated in Fig. 1A but has a different mode of operation. Shroud 290 is a two piece design having an inner shroud 220 and an outer shroud 200 where the outer shroud 200 performs multiple functions. The outer shroud 200 provides protection for the camera housing 230 by reflecting and removing radiant heat energy. It prevents rain from penetrating the camera housing 230. The outer shroud 200 also provides the means of preventing water from adhering to the optical surface 135 by providing a drip edge 208. The outer shroud 200 has vents 205 in a top portion that not only allow hot air to escape, but also allow the water to penetrate inside the outer shroud 200. The inner shroud 220 then collects the water that penetrates the vent 205 and redirects it along the inside surface 202 of the outer shroud 200 through water channels 225 located on the inner shroud 220. The inner shroud also has vents 228 in the top that let the hot air escape. These vents are above and/or offset to the vents 205 in the outer shroud 200. Thus, the water does not penetrate the inner shroud 220 and does not adhere to the camera housing 230 and impair the optical surface 135. In an alternative embodiment illustrated in Fig. 2E, at least a pair of bimetallic strips 241 are positioned over or under the vents 205. These strips are actuated to close the vents when the temperature falls below a certain level such that warm air cannot escape from the assembly during colder weather. These strips also provide insulation to keep the contents of the camera housing 130 from dropping below a certain temperature level. It will be understood that such bi-metallic strips may be used in combination with any embodiment of the invention that includes vents and function as described above. 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 (10) which comprises : a camera housing (130) having a mounting cap (140) attached to sidewalls (126) to which is attached an optical surface (135), the camera housing enclosing a camera system; and an environmental shroud (190) 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 lower section (100) having sidewalls (126A) that descend to a drip edge (108), and at least one vent (105) in a top portion thereof; and an upper section (120), at least the lower section having means that reflect and/or deflect radiant heat energy and means to remove unreflected and undeflected heat from the camera housing (130) through said vent (105), the upper section (120) covering said vent (105) and having a lower edge (125) situated below the vent and over the sidewalls (126 A) of the shroud to provide a tortuous path which prevents the penetration of water into the camera housing (130). 2. A camera assembly as claimed in Claim 1 , wherein the shroud is formed of aluminum. 3. A camera assembly as claimed in Claim 1 , wherein the means for reflecting or deflecting radiant energy is a coating on at least one surface of said shroud having a specified emissivity. 4. A camera assembly as claimed in Claim 1, wherein a ridge (103) is formed in front of the vent 105 to further assist in the removal of water from said vent. 5. A camera assembly (30) which comprises: a camera housing (330) having a mounting cap (340) attached to sidewalls (326) to which is attached an optical surface (135), the camera housing enclosing a camera system; and an environmental shroud (390) 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 section (300) having sidewalls (326 A) that descend to a drip edge (308), and at least one louvre vent (305) in a top portion thereof; at least a portion of the section (300) having means that reflects and/or deflects radiant heat energy and means to remove unreflected or undeflected heat from the camera housing (330) through said louvre vent (305), the louvre vent having a lower edge (325) situated over the sidewalls (326A) of the shroud to provide a tortuous path which prevents the penetration of water into the camera housing (330). 6. A camera assembly (20) which comprises: a camera housing (230) having a mounting cap (240) attached to sidewalls (226) to which is attached an optical surface (135), the camera housing enclosing a camera system; and an environmental shroud (290) attached to the camera housing and effective to reflect or deflect heat energy, dissipate heat energy not reflected and/or deflected, and protect the camera housing from the ingress of moisture, wherein said shroud comprises an outer shroud section (200) having sidewalls (226A) that descend to a drip edge (208), and at least one vent (205) in a top portion thereof, and an inner shroud section (220) having at least one vent (228) in a top portion thereof and at least one water channel (225) located below the vent (228)and leading to a portion of the sidewall (226A), the outer shroud vent (205) and the inner shroud vent (228) being coincident and offset relative to each other and communicating with said water channel (225) to provide a tortuous path which prevents the penetration of water into the camera housing (230), at least a portion of the outer shroud section (200) having means that reflects and/or deflects radiant heat energy and means to remove unreflected or undeflected heat from the camera housing (230) through said vents (205, 228). 7. A camera assembly as claimed in Claim 6, wherein water entering the outer shroud vent (205) is directed to the water channel(225) onto the sidewall (226A) and onto the drip edge (208) away from the camera housing (230). 8. A camera assembly as claimed in Claim 6, wherein at least a pair of bimetallic strips (241) are positioned over the outer shroud vents (205). 9. A camera assembly as claimed in Claim 8, wherein the bimetallic strips (241) are actuatable to close the vents when the temperature falls below a predetermined level. 10. An environmental shroud (190) attached to a housing (130) having a top portion (140) attached to sidewalls (126) to which is attached a bottom wall, said environmental shroud (190) 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 lower section (100) having sidewalls (126 A) that descend to a drip edge (108), and at least one vent (105) in a top portion thereof; and an upper section (120), at least the lower section having means that reflects and/or deflects radiant heat energy and means to remove unreflected and undeflected heat from the housing (130) through said vent (105), the upper section (120) covering said vent (105) and having a lower edge (125) situated below the vent and over the sidewalls (126 A) to provide a tortuous path which prevents the penetration of water into the housing (130). 11. An environmental shroud (390) attached to a housing (330) having a top portion (340) attached to sidewalls (326) to which is attached a bottom wall, said environmental shroud (390) 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 section (300) having sidewalls (326A) that descend to a drip edge (308), and at least one louvre vent (305) in a top portion thereof; at least a portion of the section (300) having means that reflects and/or deflects radiant heat energy and means to remove unreflected or undeflected heat from the housing (330) through said louvre vent (305), the louvre vent having a lower edge (325) situated over the sidewalls (326A) to provide a tortuous path which prevents the penetration of water into the housing (330). 12. An environmental shroud (290) attached to a housing (230) having a top portion (240) attached to sidewalls (226) to which is attached a bottom wall, said environmental shroud (290) being effective to reflect or deflect heat energy, dissipate heat energy not reflected and/or deflected, and protect the housing from the ingress of moisture, wherein said shroud comprises an outer shroud section (200) having sidewalls (226A) that descend to a drip edge (208), and at least one vent (205) in a top portion thereof, and an inner shroud section (220) having at least one vent (228) in a top portion thereof and at least one water channel (225) located below the vent (228)and leading to a portion of the sidewall (226A), the outer shroud vent (205) and the inner shroud vent (228) being coincident and offset relative to each other and communicating with said water channel (225) to provide a tortuous path which prevents the penetration of water into the housing (230), at least a portion of the outer shroud section (200) having means that reflects and/or deflects radiant heat energy and means to remove unreflected or undeflected heat from the housing (230) through said vents (205, 228).

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