Abstract:
A lamp assembly ( 10 ) is provided. The lamp assembly includes a lamp cover ( 12 ) having a first end ( 120 ) and an opposite second end ( 122 ). The lamp cover tapers from the second end to the first end. A hydrophobic coating ( 128 ) is formed on and covers an outer surface of the lamp cover. A light source ( 16 ) is received in the lamp cover.

Description:
BACKGROUND 
   1. Technical Field 
   The present invention relates to lamp assemblies, and particularly to an outdoor lamp assembly with a self-cleaning outer surface. 
   2. Description of Related Art 
   Surfaces of outdoor lamps have been protected against encrustation and corrosion by means of painting or coatings containing polymer films. One disadvantage of such painting or coatings is that they do not achieve multi-purpose protection since they are not generally versatile enough to protect against damage from a variety of causes. 
   What is needed, therefore, is a lamp assembly which not only can protect against encrustation and corrosion, but also has a dust and humidity protection. 
   SUMMARY 
   In a present embodiment, a lamp assembly is provided. The lamp assembly includes a lamp cover having a first end and an opposite second end. The lamp cover tapers from the second end to the first end. A hydrophobic coating is formed on and covers an outer surface of the lamp cover. A light source is received in the lamp cover. 
   Other advantages and novel features of the present invention will become more apparent from the following detailed description of preferred embodiment when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Many aspects of the lamp assembly can be better understood with reference to the following drawings. The components in the drawing are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present lamp assembly. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
       FIG. 1  is a perspective view of a lamp assembly according to an embodiment of the present invention. 
       FIG. 2  is a cross-sectional view of the lamp assembly in  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Embodiments of the present lamp assembly will now be described in detail below and with reference to the drawings. 
   Referring to  FIGS. 1 and 2 , an exemplary lamp assembly  10  includes a lamp cover  12 , a light permeable cover  14 , and a light source  16 . The light source  16  is positioned within the lamp cover  12 . 
   The lamp cover  12  includes a first opening  120  and a second opening  122 . The lamp cover  12  tapers from the second opening  122  to the first opening  120 . The first opening  120  is in the center of the lamp cover  12  and configure for receiving the light source  16  thereof. The second opening  122  has a diameter comparable in the size to the light permeable cover  14 . The walls of the lamp cover  12  at the second opening  122  and the light permeable cover  14  abut against one another, and sealed together, i.e., the permeable cover  14  is attached to the second opening  122  of the lamp cover  12 . The junction between the lamp cover  12  and the light permeable cover  14  defines a reference plane  100 . The seal may be accomplished in one of a number of ways known in the art. The union of the lamp cover  12  and the light permeable cover  14  defines a cavity  18 . 
   The wall of the lamp cover  12  includes a first portion  124  at the first opening  120  and a second portion  126  at the second opening  122 . The first portion  124  has a cup-like shape and is formed from a section of a hyperbola of revolution or other similar surface. The second portion  126  is adjacent to the first portion  124 . The second portion  126  is also formed as a section of hyperbola of revolution or other similar surface. In the present embodiment, the first portion  124  appears more like a section of a cone than the second portion  126 . Each of the first portion  124  and the second portion  126  has a focal point at or near the light source  16 . The angle α between the outer surface  124   a  of the first portion  124  and the reference plane  100  is in a range between 90° and 171.5°. The angle β between the outer surface  126   a  of the second portion  126  and the reference plane  100  is in a range between 90° and 171.5°. In the present embodiment, the angle β is smaller than the angle α, the angle α equals to 160°, and the angle β equals to 120°. 
   The light source  16  includes an electrical socket/connector  160  (e.g., a standard bulb assembly) and at least one LEDs  162 . The electrical socket/connector  160  is attached to the lamp cover  12  at the first opening  120 . When the electrical socket/connector  160  is attached to the lamp cover  12 , the at least one LEDs  162  enters the cavity  18  through the first opening  120 . 
   The light permeable cover  14  is made of transparent or translucent materials, such as glass or plastic materials. The material is colored to selectively pass light of a specific wavelength or wavelengths. Thus, the light permeable cover  14  imparts a color, which light transmitted therethrough. The light permeable cover  14  can be a plate, a lens array or a lens. The outer surface of the light permeable cover  14  is a hyperbola of revolution or other similar surface, such as a conic surface. The angle γbetween the outer surface  14 a of the light permeable cover  14  and the reference plane  100  is in a range between 90° and 135°. The lamp cover  12  and the light permeable cover  14  define a filbert-like shaped lamp assembly  10 . Water and dust on the outer surface of the lamp cover  12  can easily drop away from such a lamp assembly. 
   A hydrophobic coating  128  is formed on the outer surface of the lamp cover  12 . A transparent hydrophobic coating  140  is formed on the outer surface of the light permeable cover  14 . The hydrophobic coating  128  and the transparent hydrophobic coating  140  are water-proof coatings which have immediate uses in reducing icing and fouling of outer surface of the lamp cover  12 . Such coatings can also protect from surfaces formation of water soluble electrolytes such as acids and alkalies, and by microorganisms. 
   The hydrophobic coating  128  and the transparent hydrophobic coating  140  are at a contact angle of at least 140°. In the present embodiment, the material of the hydrophobic coating  128  can be Teflon or other hydrophobic material in the art. The material of the transparent hydrophobic coating  140  can be Polydimethylsiloxane or other similar materials. The transparent hydrophobic coating  140  in the present embodiment has a high contact angle above 165°. 
   The outer surface of the hydrophobic coating  128  and the transparent hydrophobic coating  140  can further include a rough structure. The rough structure has considerably lower profile heights and distances between profile peaks than the dust and water on the outer surface of the lamp cover  12 , so as to increase the speed of water and dust drop away from the outer surface. 
   It is understood that the above-described embodiments are intended to illustrate rather than limit the invention. Variations may be made to the embodiments and methods without departing from the spirit of the invention. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.