Abstract:
A lamp has a cover at least partially enveloping a light receptacle so as to define a receptacle chamber. A light trap is provided atop the cover with a first heat vent communicating between the receptacle chamber and an interior of said light trap and a second heat vent communicating between an interior of said light trap and an ambient environment. The light trap is arranged to at least substantially prevent light which enters the first heat vent from reaching the second heat vent while allowing heat which enters said first heat vent to pass through said second heat vent. With this arrangement, the light emitted from the cover may be blocked with a shroud without overheating the lamp.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority from U.S. provisional application No. 60/490,248, filed Jul. 28, 2003. 
     
    
     BACKGROUND OF INVENTION  
       [0002]     This invention relates to a lamp.  
         [0003]     Sabbath observant Jews may not turn electrical switches on or off during the Sabbath: from sundown on Friday until after dark on Saturday. This can force a family to leave some lights on during this period, however, the illumination may disturb others, especially those trying to sleep.  
         [0004]     This invention seeks to ameliorate this problem.  
       SUMMARY OF INVENTION  
       [0005]     The subject lamp reduces the inconvenience caused by a lamp that remains electrically turned on by providing a lamp suitable for reading or other purposes that is adapted to selectively provide light.  
         [0006]     The lamp has a cover at least partially enveloping a light receptacle so as to define a receptacle chamber. A light trap is provided atop the cover with a first heat vent communicating between the receptacle chamber and an interior of said light trap and a second heat vent communicating between an interior of said light trap and an ambient environment. The light trap is arranged to at least substantially prevent light which enters the first heat vent from reaching the second heat vent while allowing heat which enters said first heat vent to pass through said second heat vent. With this arrangement, the light emitted from the cover may be blocked with a shroud without overheating the lamp.  
         [0007]     Accordingly, the present invention provides a lamp comprising: a light receptacle; a cover at least partially enveloping said light receptacle so as to define a receptacle chamber; a light trap atop said cover; a first heat vent communicating between said receptacle chamber and an interior of said light trap; a second heat vent communicating between an interior of said light trap and an ambient environment; said light trap arranged to at least substantially prevent light which enters said first heat vent from reaching said second heat vent while allowing heat which enters said first heat vent to pass through said second heat vent.  
         [0008]     Other features and advantages will become apparent from a review of the following description in conjunction with the drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     In the figures which illustrate example embodiments of the invention,  
         [0010]      FIG. 1  is and exploded view of a lamp made in accordance with this invention,  
         [0011]      FIG. 2  is a cross-sectional view of the lamp of  FIG. 1 ,  
         [0012]      FIG. 3  is a cross-sectional view along the lines  3 - 3  of  FIG. 2 ,  
         [0013]      FIG. 4  is a perspective view of a lamp made in accordance with another aspect of this invention, and  
         [0014]      FIG. 5  is a cross-sectional view of the lamp of  FIG. 4 . 
     
    
     DETAILED DESCRIPTION  
       [0015]     Broadly, the lamp allows the escape of heat even when light from the lamp is blocked. In this regard, the lamp may have a moveable shade body providing a selectively sized aperture for allowing emission of a selective amount of light.  
         [0016]     Turning to  FIGS. 1 through 3 , a table lamp  10  has a top unit  12  having a cylindrical tubular shroud  14  with a side wall  16  having an opening  18  therethrough. The opening is covered with a translucent light diffusing sheet  19 . The lumen of the shroud is lined with a reflective sheet  21  opposite opening  18 . A light trap  20  extends from the top end of the tubular shroud  14 . As seen in  FIGS. 2 and 3 , there is an off-center heat vent hole  22  in the bottom wall  24  of the light trap inside of the cylindrical side wall  16  of tubular body  14 . There is a second heat vent hole  26  in a side wall  28  of the light trap. A series of baffles  30  extend between the two heat vents so as to provide a tortuous path between the two heat vents.  
         [0017]     A bottom unit  32  has a base  34  with a tubular cover  36  extending upwardly therefrom. The tubular cover  36  has a side wall  38  having an aperture  40  (the other like shaped areas of side wall  38  are not apertures). The base houses a light receptacle  42  extending inside of the cover  36  for a light  44 . Thus, the cover defines a receptacle chamber  45 . A cord  46  for the receptacle runs through the base  34 . An annular support  50  extends from the base  34  within the cover  36 . A bearing ring  52  rests on the annular support  50  and the base of the shroud  14  rests on the bearing ring  52 . The shroud  14  and cover  36  are sized so that the clearance between the top of the cover and the bottom wall  24  of the light trap is small. Additionally, the clearance between the side wall  16  of the shroud and the side wall  38  of the cover  36  may be small. In consequence little, if any, light can escape through the top of the cover with the shroud resting on the ring bearing  52 .  
         [0018]     In operation, the light trap  20  may be grasped by a user and the top unit  12  rotated with respect to the bottom unit  36  so that the opening  18  in the shroud wall  16  may be partially or fully aligned with the aperture  40  in the cover  36 . In this way, with the light  44  illuminated, a selective amount of light may be emitted from the lamp  10 . Further, with the light illuminated, heat is vented through the vent holes  22 ,  26  in the light trap  20 . However, little if any light can escape from the light trap because of the baffles  30  intervening between the vent holes.  
         [0019]     Sabbath observant Jews are not permitted to move a light source. It will be apparent from the foregoing that when a user grasps the light trap  20  of lamp  10  and rotates the top unit  12 , the bottom unit  36  does not move. Further, it is the bottom unit that supports the light receptacle  42 . Consequently, the user does not move the light supporting bottom unit when rotating the top unit. Therefore, lamp  10  may be operated by Sabbath observant Jews.  
         [0020]     The amount of light leaving the lamp is dependent upon the degree of overlap of the opening  18  in the shroud wall  16  and the aperture  40  in the side wall  38  of the cover  36 . This degree of overlap is selected by a user rotating the top unit  12 .  
         [0021]     The shroud opening  18  may have a diffuser sheet  19  to diffuse light emitted by the lamp. The lamp may use high efficiency (low energy) bulbs. The reflective backdrop  21  increases the light emerging from the lamp when the cut-outs are aligned.  
         [0022]     There are at least the following unique aspects of this lamp: 
        A non-electric dimming function: the amount of light emitted can be varied manually by rotating the shroud; the effect of a “dimmer” is accomplished with no special electronics nor special bulb.     A directional reading lamp: the shroud and cover, with their defined openings allow, for example, one person in a bedroom to read without the light disturbing another person sleeping in the room.     Sabbath use: the lamp can be effectively “turned off” without requiring electrically switching off the light and without moving the light source; this allows Sabbath observant Jews who may not turn electrical switches on or off to use the lamp as a bedside reading lamp on the Sabbath.        
 
         [0026]     Thus, Sabbath use is only one of the uses of the subject lamp and lamp shade.  
         [0027]     Optionally, more than one vent hole  22  and vent hole  26  may be provided so long as the baffles provide a tortuous path between all of the vent holes  22  in the bottom of the light trap and the vent holes  26  in the side of the light trap. Optionally, the base  34  may be enclosed and have an upper wall with at least one vent into the base separated from one or more holes in the side of the base by baffles. This would provide another egress for heat, while trapping light.  
         [0028]     Rather than have the reflective backdrop lining the lumen of the shroud, it may be affixed to the inner surface of the base such that the light bulb is between the reflective backdrop and the aperture  40  in the side wall  38  of the cover  36 .  
         [0029]     Other arrangements may also be used to provide a table lamp which may allow a selective amount of light to emerge. For example, the shroud could comprise a box which may be opened a selective amount, which box may have a mirror as the backdrop such that the box also functions as a jewellery box. As a further alternative, the lamp could have a shroud with a sliding door or shutters. In all instances, a light trap may be provided above the light receptacle.  
         [0030]     This invention may also be embodied in a wall lamp as, for example, the wall lamp  100  of  FIGS. 4 and 5 . Turning to these FIGS., wall lamp  100  has a cover  136  with a frusto-conical cover side wall  137  and a bottom wall  138  with an arcuate aperture  140  therein. The top wall  124  of the cover supports a light receptacle  142  for a light  144 . Thus, the cover defines a receptacle chamber  145 . A cord  146  for the receptacle runs through a tube  139  extending from the side wall  137  of the cover to a base  134 . A light trap  120  extends from the top end of the cover  136 . As seen in  FIG. 5 , there is an off-center heat vent hole  122  in the top wall  124  of the cover—which is also the bottom wall of the light trap—inside of the frusto-conical side wall  137  of cover  136 . There is a second heat vent hole  126  in a side wall  128  of the light trap. A series of baffles  130  extend between the two heat vents so as to provide a tortuous path between the two heat vents.  
         [0031]     The wall  116  of a disk-shaped shroud  114  has an arcuate opening  118  therethrough. The shroud  114  is centrally mounted to the bottom wall  138  of cover  136  by pivot  152  so that the shroud can be rotated with respect to the bottom wall  138  of cover  136 .  
         [0032]     In operation, the shroud may be rotated (by rotating the pivot  152 ) so that the opening  118  in the shroud is selectively aligned with aperture  140  in the bottom wall  138  of the cover  136 . In this way, a selective amount of light may be emitted from lamp  100 . Again, the light trap  120  acts to vent heat from the lamp, while trapping light.  
         [0033]     Other modifications will be apparent to those skilled in the art and, therefore, the invention is defined in the claims.