Abstract:
A removable, reusable cover assembly for a light assembly has a light filtering cover with an interior that surrounds a lamp of the light assembly and a connector that attaches to the light assembly. The cover assembly has first and second vent holes that communicate with the interior of the cover. During energization of the lamp, the air in the interior of the cover is heated and escapes through the first vent hole. Cooling air is drawn through the second vent hole into the interior of the cover to cool the lamp.

Description:
BACKGROUND OF THE INVENTION 
     (1) Field of the Invention 
     The present invention pertains to a protective cover for a lamp and in particular to a reusable color filter that can be removably attached to the mounting assembly of a halogen lamp used in an emergency warning light to protect the lamp and change the color of the light emitted by the lamp while providing a flow of air to cool the lamp. 
     (2) Description of the Related Art 
     From 1915 to 1950, virtually all emergency warning lights were devices that incorporated an incandescent lamp and a parabolic reflector, both mounted behind an essentially flat color glass filter. The reflector directed light emitted from the lamp through the colored glass filter. The flashing of the light was produced by interrupting the current to the lamp. Although these devices were simple and inexpensive, they were considered to have two serious deficiencies. 
     First, the emergency warning lights were highly directional and projected a flash of warning light in only a fraction of the perimeter around the vehicle on which the warning light was mounted. Second, because it was necessary to reheat the lamp filament at the start of each flash, the warning lights were very inefficient. 
     In the late 1940&#39;s, the rotating beacon warning light was developed. The rotating beacon also used an incandescent lamp and a parabolic reflector positioned behind the lamp. However, flashes of the lamp were obtained by using a small motor to rotate the lamp and reflector together inside a colored, circular lens. Although the rotating beacon warning light eliminated the previous directional deficiencies of warning lights, using the same single light source as the previous directional warning light (typically a 30-60 watt bulb), the 360° signal emanating from the rotating beacon was not nearly as intense as that generated by the older directional devices that concentrated their energy in an arc of about 30°. 
     To overcome the shortcomings of the rotating beacon signal light, a sealed beam spotlight lamp was used in place of the bulb and reflector. By using as many as 4 sealed beam spotlight lamps mounted on a common turntable, acceptable levels of warning light flashes were achieved in all directions around the vehicle on which the rotating sealed beam spotlight lamp warning light was mounted. 
     Whether a directional warning light, a single lamp rotating or multiple lamps rotating warning light, all warning lights typically used a colored lens to produce a light signal of a single color. For a few special applications, two lenses were cut in half and glued together to form a split lens that, for example, flashed red to the front and yellow to the rear. 
     After the introduction of the multiple sealed beam spotlight lamp beacon, they were modified by putting colored faces on the spotlight lamps and enclosing the multiple spotlight lamps inside a clear lens. Combinations of red and clear colored faces on the spotlight lamps were also used. However, the sealed beam spotlight lamps were disadvantaged in that they were expensive and relatively heavy. They required large and expensive motors and turntables to support and rotate the spotlight lamps. In addition, it was noticed that in those signal lights employing colored faces on the spotlight lamps that the colors were not very heat resistant and would burn away. 
     In the mid-1970&#39;s, the lightbar emergency warning light was introduced. Basically, the lightbar was constructed of a series of rotating spotlight beacons mounted in a row under rectangular lenses. However, it was soon discovered by police departments that their cars equipped with lightbars using colored lenses could be seen for miles, even when the warning lights were off. Cars using lightbars with clear lenses over colored sealed beam lamps were equally effective with their lights on, but were much less visible with their lights off. 
     Halogen headlights using replaceable halogen capsules were introduced in the 1980&#39;s and soon ended the use of conventional sealed beam lamps for headlights. By using the same inexpensive halogen capsule, warning light manufacturers realized they could produce a less expensive but higher performance product. However, the halogen lamp could not be used with the conventional clear lenses. The halogen lamps burn very hot and required envelopes of special glass and it was found to be impractical to color the glass as was done for sealed beam spotlight lamps. 
     To overcome this problem, several filter designs were developed, such as that disclosed in U.S. Pat. No. 4,543,622. The filter design of this patent was successful when used with 360° rotating light elements and is still widely used. With rotating signal light elements, the common method for obtaining color signals from a halogen lamp under a clear lens is to attach a filter to the reflector of the signal light element so that it rotates with the reflector. However, when this is attempted with an oscillating signal light having an oscillating reflector of the type described in U.S. Pat. No. 5,385,062; U.S. Pat. No. 5,697,691; U.S. Pat. No. 5,842,768 and U.S. Pat. No. 5,676,447, the filter adds substantial weight to the light element and changes the arc of coverage of the warning light signal. 
     Colored halogen warning signal lamps have been designed that have a close fitting colored glass tube positioned over the halogen bulb. One end of the colored glass tube is closed and the other end is open. A standard halogen lamp is inserted into the tube and a high temperature cement is used to permanently bond the open end of the colored glass filter tube to the metallic base of the halogen lamp. However, the close fitting glass tube appreciably increases the operating temperature of the halogen lamp. These lamps with colored tubes were primarily designed for use in a current interrupted flashing warning light with less than a 50% duty cycle. It was found when these lamps were used in a 100% duty cycle device, such as a rotating or oscillating beacon, the halogen lamp life was less than half of that obtained when the halogen lamp is operated without the colored filter. The addition of the close fitting, closed filter increases the internal temperature of the halogen bulb and leads to its rapid failure. In addition, the manufacture of a halogen lamp with a permanent color filter secured over the lamp bulb significantly increases the price of the halogen lamp alone. With less than half of the useful life of the halogen lamp at a significant increase in cost over the halogen lamp, the use of the halogen lamp with the colored filtered tube was considered too impractical for use in continuous duty warning lights. 
     What is needed to overcome the shortcomings experienced in providing color to a signal light produced by a halogen lamp in an oscillating or rotating signal light assembly under a clear lens is a high temperature, colored filter that does not affect the performance of either the halogen lamp or the signal light assembly. The filter should be easily removable from the standard halogen lamp to permit reuse whenever the halogen lamp is replaced. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the disadvantages of the prior art by providing a reusable cover assembly that attaches to a standard halogen lamp or any other high temperature light source having a socket and a lamp in the socket. The cover assembly preferably changes a color of light emitted by the lamp while providing a sufficient flow of cooling air through the reusable cover assembly to minimize any reduction in the operating life of the lamp. The reusable cover assembly of the invention does not impede the operation of the oscillating or rotating element or require expensive segmented lenses around the oscillating element. The cover assembly not only filters light emitted by the lamp, but also functions as a protective cover over the lamp that protects the lamp from accidental contact. 
     The reusable cover assembly of the present invention includes a metallic connector that attaches to the lamp or lamp socket of a signal light assembly and a cover in the form of a high temperature colored filter that surrounds the lamp. The connector easily snaps over a standard halogen lamp and lamp socket and holds the reusable cover assembly securely to the signal light assembly. The connector permits easy removal of the cover assembly from the signal light assembly when the lamp burns out and allows easy installation of the reusable cover assembly over a replacement lamp. 
     The connector of the cover assembly has a filter or cover mounting portion that is connected to a lamp or lamp socket mounting portion. The lamp or lamp socket mounting portion attaches to the lamp or lamp socket of the signal light assembly and the cover mounting portion supports the colored filter over the signal light lamp. The connection between the filter or cover mounting portion of the connector and the colored filter or cover is flexible to compensate for the differences in the coefficient of thermal expansion between the filter and the filter mounting portion of the connector. Because the connection between the connector and filter is subjected to a wide range of temperatures as the lamp is switched from a de-energized state to a prolonged operating state, the flexible connection between the connector and filter ensures the integrity of the cover assembly. 
     The metallic connector has an arrangement of vent openings that permit entry of cooling air into the cover assembly and between the colored filter lamp cover and the lamp. The filter cover is provided with a top vent hole to permit exiting of air heated by the lamp from inside the cover. Cooling air enters through the arrangement of vent openings in the cover assembly, flows between an interior space between the lamp and the filter cover thereby cooling the lamp to keep it operating properly for a longer period of time, and then escapes through the top vent hole of the filter cover. The top of the colored filter cover or the area of the cover around the top vent hole is preferably rounded and/or tapered to minimize the passage of unfiltered white light from the lamp through the vent hole. 
     The reusable cover assembly of the present invention provides colored light for a warning signal light yet does not appreciably affect the performance of the halogen lamp or the oscillation means by which the signal light assembly is rotated or oscillated through an arc. The reusable cover assembly of the invention is easily removable from the lamp or lamp socket of the standard signal light assembly and permits reuse whenever the halogen lamp is replaced. In addition to providing a colored filter for the halogen lamp, the cover assembly also protects the lamp from accidental contact. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further objects and features of the invention are revealed in the following detailed description of the preferred embodiment of the invention and in the drawing figures wherein: 
     FIG. 1 is a front perspective view of a cover assembly of the present invention; 
     FIG. 2A is a front perspective view of a lamp and lamp socket of a signal light assembly on which the cover assembly of FIG. 1 is used; 
     FIG. 2B is a front perspective view of an alternative embodiment of a lamp and lamp socket of a signal light assembly on which the cover assembly of FIG. 1 is used; 
     FIG. 3A is a front perspective view of the cover assembly of FIG. 1 installed on the lamp and lamp socket of the signal light assembly of FIG. 2A or FIG. 2B; 
     FIG. 3B is a partial sectional view of the cover assembly and the signal light assembly of FIG. 3A; 
     FIG. 4 is a rear perspective view of the cover assembly of FIG. 1; 
     FIG. 5A is front elevation view of the cover assembly of FIG. 1; 
     FIG. 5B is a top cross-sectional view of the cover assembly of FIG. 1 along lines  5 B— 5 B of FIG. 5A; 
     FIG. 6 is a perspective view of the connector of the cover assembly; and 
     FIG. 7 is a perspective view of the cover assembly and signal light assembly of FIG. 3A installed on an oscillating or rotating element. 
     Corresponding reference numerals indicate corresponding parts through the several views of the drawings. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1 and 4 show the cover assembly  10  of the invention with FIG. 1 showing one side of the cover assembly and FIG. 4 showing the opposite side. The cover assembly is basically comprised of a signal light connector  12  and a lamp cover  14 . In the preferred embodiment, the signal light connector  12  has a cylindrical shape as shown in the drawing figures that enables it to be mounted over the cylindrical exterior surface of a conventional signal light assembly  15 . However, when the cover assembly  10  is intended to be used with a signal light assembly having an exterior configuration that is other than cylindrical, the shape of the signal light connector  12  will change to enable it to be mounted over the particular signal light assembly in the manner to be described. In the preferred embodiment, the signal light connector  12  is constructed of metal that gives the connector a resiliency. However, other similar types of resilient materials may also be employed. 
     The lamp cover  14  in the preferred embodiment is constructed of glass that is color tinted. This enables the lamp cover  14  to function as a colored filter for the halogen lamp or other high temperature bulb of the signal light assembly on which the cover assembly is used. However, the lamp cover  14  will also protect the halogen lamp from inadvertent contact. If the cover  14  is to function as only a protection for the halogen lamp or other high temperature lamp with which the cover assembly is used, it is not necessary that it be constructed of a color tinted glass and could be constructed of a clear glass. Still further, the lamp cover  14  could function as both a protector for a high temperature lamp on which the cover assembly is used and also function as a means for directing a beam of light from the lamp through a hole in the cover to be described. When the lamp cover  14  is used for this particular function, it could be constructed of opaque glass or other opaque materials such as ceramics. In the drawing figures, the lamp cover  14  is shown as having a general cylindrical configuration. However, the configuration of the lamp cover  14  will be determined by the configuration of the high temperature lamp with which it is used and could have other configurations, for example spherical. 
     In the preferred embodiment, the lamp cover  14  functions as both a color filter for a halogen or other high temperature lamp and as a protective cover for the lamp. The lamp cover  14  has a cylindrical configuration along most of its length with a circular lamp opening  16  at one end of its length and a rounded end  18  at the opposite end of its length. The cylindrical configuration of the lamp cover  14  is determined to be sufficiently large to provide the lamp cover  14  with an interior volume  22  that will easily accommodate the lamp of the signal light assembly  15  with which the cover assembly is to be used and provide a spacing between the exterior surface of the lamp and the interior surface  24  of the lamp cover  14  when the cover is positioned over the lamp. Centered in the rounded end  18  of the filter cover is a first vent hole  26 . The vent hole  26  is dimensioned significantly smaller than the lamp opening  16  of the cover. The reduced size of the vent hole  26  is provided to reduce or minimize the passage of any unfiltered light from the lamp with which the cover assembly is used through the vent hole. However, the vent hole  26  is still dimensioned sufficiently large to allow air heated in the cover interior volume  22  to easily escape from the interior through the vent hole  26 . 
     The signal light connector  12  has a cylindrical length with a socket opening  32  at one end a lamp opening  34  at the opposite end. An axial slot  36  is formed through the connector between its socket opening end  32  and the lamp opening end  34 . The slot  36  is traversed by a circumferential cut  38  formed in the connector. The circumferential cut  38  extends almost entirely through the signal light connector  12  and extends from the axial slot  36  beyond a center axis  42  of the connector and stops short of entirely passing through the connector leaving a web  44  on the connector opposite the axial slot  36 . The cut  38  functions as second vent hole or vent opening of the cover assembly  10  as will be explained. The cut  38  separates the signal light connector  12  into two sections, a cover mounting section  46  and a socket mounting section  48 . As can be seen in the drawing figures, the socket mounting section  48  has a larger axial length than the cover mounting section  46 . The position of the cut  38  and the axial slot  36  form the cover mounting section  46  of the signal light connector  12  as two resilient, arcuate fingers  52 . The circumferential cut  38  and the axial slot  36  also form the signal light connector  12  with a pair of resilient, arcuate base members  54 . The fingers  52  are enlarged radially outwardly from the connector center axis  42  so that an interior diameter of the arcuate fingers  52  is slightly larger than the interior diameter of the arcuate base members  54 . The arcuate fingers  52  are deformed radially outwardly so that an exterior diameter defined by the arcuate fingers is slightly larger than an interior diameter of the lamp opening  16  of the lamp cover  14 . 
     A third venting opening or aperture  62  is formed in the web  44  of the signal light connector  12 . This third vent aperture  62  is formed by cutting a small, inverted U-shaped cut in the web  44  and bending the tab formed by the cut radially inwardly from the web  44 . This forms the vent aperture  62  in the web  44  and also forms a web protrusion  64  on the interior surface  66  of the signal light connector  12 . 
     The circumferential cut  38  and the axial slot  36  in the signal light connector  12  also form the arcuate base members  54  with spaced distal ends having mutually opposed cut corners  72  adjacent the circumferential cut  38  and socket corners  74  adjacent the signal light connector socket opening  32 . The cut corners  72  are bent slightly, radially inwardly. The cut corners  72 , together with the web protrusion  64  accurately position the cover assembly  10  on the lamp or lamp socket of the signal light assembly  15  as will be explained. The socket corners  74  are bent slightly, radially outwardly. This configuration of the socket corners  74  facilitates the attachment of the socket connector  12  on the signal light assembly  15 . 
     The lamp cover  14  is assembled on the signal light connector  12  by first resiliently biasing the arcuate fingers  52  of the cover mounting section  46  radially inwardly toward each other. The displaced fingers  52  are then inserted into the lamp opening  16  of the filter cover  14 . The radially inwardly biasing force on the arcuate fingers  52  is then released, allowing them to expand radially outwardly and engage with the interior surface  22  of the filter cover adjacent the cover lamp opening  16 . To securely hold the bulb filter cover  14  to the signal light connector  12 , a high temperature elastomer, such as a silicone rubber, can be applied to the connection between the lamp cover  14  and the arcuate fingers  52  of the signal light connector  12 . By employing a high temperature elastomer, the lamp cover  14  and, in particular, the portion of the cover adjacent the lamp opening  16  is free to expand and contract when subjected to the heat of a signal light lamp independently of the expansion and contraction of the arcuate fingers  52  also subjected to the lamp heat. The high temperature elastomer compensates for any difference in the expansion and contraction of the lamp cover  14  and the arcuate fingers  52  and maintains a secure connection between the lamp cover  14  and the signal light connector  12 . 
     The cover assembly  10  is removably attached to the signal light assembly  15  by inserting the signal light connector  12  over the signal light assembly  15  with the lamp  84  passing through the signal light connector socket opening  32  and the lamp opening  16  of the lamp cover  14 . The socket corners  74  facilitate in the passage of the signal light connector socket opening  32  over the signal light assembly exterior surface  86 . 
     FIG. 2A show one type of signal light assembly  15  that is comprised of a lamp  84  mounted in a lamp socket  87 . In this embodiment of the signal light assembly, the lamp  84  has a protruding rim  88  on its base. In attaching the cover assembly to the signal light assembly  15  of FIG. 2A, the arcuate base members  54  of the signal light connector  12  pass over the lamp  84  and the exterior surface of the lamp socket  87  until the two cut corners  72  of the base members snap over the protruding rim  88  on the lamp  84  and the web protrusion  64  of the connector comes into contact with a top edge of the protruding rim  88 , thereby removably attaching the lamp cover  14  on the signal lamp assembly  15 . 
     FIG. 2B shows a slightly different type of signal light assembly that is comprised of a lamp  84  mounted in- a lamp socket  90 , but in this embodiment of the signal light assembly, the socket  90  has a protruding rim  92 . In attaching the cover assembly to the signal light assembly  15  of FIG. 2B, the arcuate base members  54  of the signal light connector  12  pass over the lamp  84  and the exterior surface of the lamp socket  90  until the two cut corners  72  of the base members snap over the protruding rim  92  on the lamp socket  90  and the web protrusion  64  of the connector comes into contact with a top edge of the protruding rim  92 , thereby removably attaching the lamp cover  14  on the signal lamp assembly  15 . 
     The web protrusion  64  limits the downward movement of the cover assembly  10  on the signal light assembly  15  while the cut corners  72  prevent upward movement of the cover assembly  10  on the signal light assembly  15 . The web protrusion  64  and the cut corners  72  act on opposite sides of the protruding rim to prevent the cover assembly  10  from inadvertently separating from the signal light assembly  15  during operation. However, pulling upward with modest force allows the cover assembly  10  to be removed from the signal light assembly  15 , for instance, as would be necessary when changing the lamp  84 . The lamp  84  has a bayonet style base that allows the lamp  84  to be removed from the socket by rotating the lamp  84  in the socket and pulling upward. 
     With the cover assembly  10  positioned on the signal light assembly  15 , operation of the lamp  84  will generate heat in the interior volume  22  of the lamp cover  14 . With the cover assembly  10  and signal light assembly  15  positioned in an upward orientation, the heated air in the lamp cover  14  will rise and pass through the vent opening  26  at the top of the lamp cover  14 . This will draw cooling air through the second vent opening provided by the circumferential cut  38  and the third vent opening provided by the vent aperture  62  of the web into the interior volume  22  of the filter cover, thus cooling the lamp  84 . In this manner, the cover assembly  10  provides a color tint to the halogen lamp  84  or other high temperature lamp  84  of the signal light assembly  15  without appreciably increasing its operating temperature due to the venting of the lamp cover  14 . The lamp cover  14  also functions to prevent inadvertent contact with the lamp  84  of the signal light assembly  15 . 
     While the present invention has been described by reference to a specific embodiment, it should be understood that modifications and variations of the invention may be constructed without departing form the scope of the invention defined in the following claims.