Abstract:
The present invention is to provide a better design, and a uniform and bright lighting to a cover lens. A lamp holder holds a lamp L and a lamp bezel holds the lamp holder. The lamp bezel is attached to a roof of a vehicle. The cover lens covers a front side of the lamp bezel and the lamp holder. A part of the cover lens is embossed so as that the lamp holder is hardly visible through the cover lens from a front side of the cover lens. The part is thinly embossed as approaching to a periphery of the part in order to increase a light transmittance.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a lamp unit, more specifically to a lamp unit having a lamp holder to hold a lamp, a lamp attachment for holding the lamp holder and being attached to an object, and a transparent cover attached to the lamp attachment and covering a front side of the lamp attachment and the lamp holder.  
         [0003]     2. Description of the Related Art  
         [0004]      FIGS. 6A and 6B  show a conventional room lamp as a lamp unit to be attached to a roof of a vehicle. Refer to JP-2004-203344,A.  FIG. 6A  is a front view of the room lamp and  FIG. 6B  is a front perspective view thereof with a cover lens  30  being removed.  
         [0005]     As shown in  FIGS. 6A and 6B , the room lamp includes a lamp holder  10  to hold a lamp L, a lamp bezel (lamp attachment)  20  for holding the lamp holder  10  and being attached to the roof of the vehicle, and the cover lens (transparent cover)  30  attached to the lamp bezel  20  and covering all over a front side of the lamp bezel  20  and the lamp holder  10 .  
         [0006]     The lamp bezel  20  has a lamp window  21  in the center and holds the lamp holder  10  for the lamp L to be exposed to the front side thereof through the lamp window  21 . The lamp bezel  20  has attachment portions  24 , such as engaging claws, to be engaged with engaged holes (not shown) disposed at the roof of the vehicle, at a rear surface thereof. The lamp bezel  20  has a plurality of through-holes  25  therein. The plurality of the through-holes  25  are formed when the attachment portions  24  are formed by die-cutting the lamp bezel  20 . Screw holes also become the through-holes  25 .  
         [0007]     As shown in  FIG. 6B , the lamp bezel  20  has sliding grooves  23  in a longitudinal direction thereof. A sliding member  40  is slidably engaged with the sliding grooves  23  at the front side of the lamp bezel  20 . A knob  41  is disposed at a front side of the sliding member  40  and exposed to outside from a front opening  31  of the cover lens  30 . The sliding member  40  is slid by means of the knob  41  so as to turn on and off the lamp L.  
         [0008]     A whole area of a rear surface of the cover lens  30  is embossed so as that the lamp holder  10 , the through-holes  25  formed in the lamp bezel  20 , and the sliding grooves  23  are not visible from a front side of the room lamp, i.e., the cover lens  30  appears cloudy.  
         [0009]     Then, the cover lens  30  loses transparency and appearance design. In the conventional lamp unit, the cover lens  30  is embossed entirely and has a uniform light transmittance. However, when the cover lens  30  is embossed thinly in order to increase the light transmittance and brightness, the lamp holder  10  or through-holes  25  formed in the lamp bezel  20  becomes visible through the cover lens  30 . On the contrary, when the cover lens  30  is embossed densely for the lamp holder  10  or the through-holes  25  to be invisible, the brightness is reduced.  
         [0010]     The uniform light transmittance of the conventional cover lens  30  results in that the brightness of the cover lens  30  is high at an area close to the lamp L and becomes lower with a distance from the lamp L.  
       SUMMARY OF THE INVENTION  
       [0011]     The present invention is to provide a better design, and a uniform and higher brightness to a cover lens of a lamp unit.  
         [0012]     According to a first aspect of the present invention, a lamp unit includes a lamp holder to hold a lamp; a lamp attachment for holding the lamp holder and being attached to an object; a transparent cover attached to the lamp attachment and for covering a front side of the lamp attachment and the lamp holder; wherein the transparent cover has a part having a less light transmittance than that of an area outside the part, the lamp holder being visible through the part from a front side of the transparent cover.  
         [0013]     Preferably, the part of the transparent cover is embossed.  
         [0014]     Preferably, the part has a high light transmittance as approaching to a periphery of the part.  
         [0015]     Preferably, the transparent cover has a plurality of prism lenses having a square pyramid shape at a rear surface thereof.  
         [0016]     Preferably, the lamp unit further includes opaque covers attached to the lamp attachment and covering all over through-holes from the front side of the lamp attachment, and the transparent cover is attached in front of the opaque covers.  
         [0017]     Preferably, the lamp attachment has sliding grooves and a sliding member, which is disposed at the front side of the lamp attachment and slidably engaged with the sliding grooves and has an operating knob exposed from the transparent cover, and the sliding member always covers all over the sliding grooves irrespective of the location of the sliding member within a sliding range.  
         [0018]     Preferably, the lamp attachment is attached to the object with the front side down, the opaque covers are attached on a line extending from a sliding direction, and the sliding member is formed to extend into the sliding direction so as to have overlapped portions with at least a portion of the opaque covers irrespective of the location of the sliding member within the sliding range. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]      FIG. 1  is an exploded front perspective view of a room lamp of an embodiment of a lamp unit of the present invention;  
         [0020]      FIG. 2  is a front view of the room lamp of  FIG. 1  with a cover lens  30  being removed;  
         [0021]      FIG. 3  is a sectional view taken along a line  3 - 3  of  FIG. 2 ;  
         [0022]      FIG. 4A  is a partial rear view of the cover lens  30  of  FIG. 1 ;  
         [0023]      FIG. 4B  is a partial side view of prism lenses P disposed at a rear surface of the cover lens;  
         [0024]      FIG. 5  is a front view of the lamp unit of  FIG. 1 ;  
         [0025]      FIG. 6A  is a front view of a conventional room lamp; and  
         [0026]      FIG. 6B  is a front perspective view of the room lamp with a cover lens  30  being removed. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]     A lamp unit of the present invention is explained by referring to figures.  FIG. 1  is an exploded front perspective view of a room lamp of an embodiment of the lamp unit of the present invention.  FIG. 2  is a front view of the room lamp with a cover lens  30  in  FIG. 1  being removed. As shown in  FIG. 1 , the room lamp has a lamp holder  10  to hold a lamp L, a lamp bezel  20  (lamp attachment) having a rectangular plate shape for holding the lamp holder  10  and being attached to a roof of a vehicle, and the transparent cover lens  30  (transparent cover) attached to the lamp bezel  20  and covering all over a front side of the lamp holder  10  and the lamp bezel  20 .  
         [0028]     The lamp bezel  20  is attached to the roof of the vehicle with a front side of the cover lens  30  down. The lamp bezel  20  has the lamp holder  10  for the lamp L to appear from a lamp window  21  disposed at the center of the cover lens  30 . As shown in  FIG. 1 , the lamp bezel  20  has attachment portions  24 , such as roof attachment projections  24   a  and body attachment projections  24   b,  disposed at a rear surface thereof and both ends in a direction Y 1  to which the lamp window  21  slides. As described later, a sliding member  40  slides into the direction of Y 1 .  
         [0029]     As shown in  FIG. 1 , the lamp bezel  20  has a plurality of through-holes  25  therein. In this embodiment, the plurality of the through-holes  25  are formed when the attachment portions  24  are formed by die-cutting the lamp bezel  20 . Screw holes also become the through-holes  25 . A pair of opaque covers  50  are disposed on both sides of the lamp bezel  20  in the direction of Y 1  and cover all over the through-holes  25  from the front side of the bezel  20 . The opaque covers  50  are engaged with engaged holes of the lamp bezel  20  by means of engaging claws  51  of the opaque covers  50 . The opaque covers  50  cover the through-holes  25  so as that the through-holes  25  are not visible when they are viewed from a front side of the lamp bezel  20  with the cover lens  30  removed.  
         [0030]     As shown in  FIG. 2 , the lamp bezel  20  has sliding grooves  23  in a longitudinal direction thereof. The sliding member  40  is slidably engaged with the sliding grooves  23  at the front of the lamp bezel  20 . Locking claws are disposed behind of the sliding member  40  and slidably engaged with the sliding grooves  23 . A knob  41  is disposed at the front of the sliding member  40  and exposed to outside from a front opening  31  of the cover lens  30 . The sliding member  40  is slid by means of the knob  41  so as to turn on and off the lamp L.  
         [0031]     A part of the each opaque cover  50  is placed on a line L 1  extending from the sliding direction of Y 1 . The sliding member  40  extends into the sliding direction of Y 1  so as to always cover the front faces of the parts of the opaque covers  50  irrespective of the location thereof within a sliding range.  
         [0032]     As shown in  FIGS. 2 and 3 , when the sliding member  40  is slid to a side of Y 11  in the sliding direction of Y 1 , an overlapped portion O is formed between the sliding member  40  and the opaque cover  50  at a side of Y 12 . When the sliding member  40  is slid to a side of Y 12  in the sliding direction of Y 1 , the overlapped portion O is similarly formed between the sliding member  40  and the opaque cover  50  at a side of Y 11 . Accordingly, the sliding member  40  always covers all of the sliding grooves  23  irrespective of the location thereof so that the sliding grooves  23  can not be seen from the front side of the lamp bezel  20  with the cover lens  30  being removed.  
         [0033]     As shown in  FIGS. 4A and 4B , the cover lens  30  has a plurality of prism lenses P having a square pyramid shape at a rear surface thereof. In the embodiment of the present invention, the square pyramid is not limited to a rigorous square but includes pyramids having rounded top or corners. As shown in  FIGS. 1 and 5 , a part A of the rear surface of the cover lens  30  is embossed so as to diffusely reflect a light from the lamp L. The part A is an area through which the lamp holder  10  is visible from the front side of the cover lens  10 . An area between the prism lenses P is embossed as shown by diagonal lines in  FIG. 4A .  
         [0034]     Accordingly, a light transmittance of the part A is reduced compared to an other area surrounding the part A. Thus, the lamp holder  10  can not be seen clearly from the front side of the cover lens  30 . Since the other area surrounding the part A is not embossed, the cover lens  30  keeps a high light transmittance and provides a clear appearance so that a design and brightness are improved. The cover lens  30  is embossed only in the part A close to the lamp L to reduce the light transmittance compared to the other area of the cover lens so that the uniform brightness at the cover lens  30  is attained.  
         [0035]     As shown in  FIG. 5 , a peripheral area of the part A, denoted by coarse diagonal lines, is embossed thinly compared to the area inside the periphery, denoted by fine diagonal lines, so as to increase the light transmittance at the peripheral area. With a stepped increase of the light transmittance along a direction from the center of the part A to the peripheral area, a boundary between the embossed part A and the other area surrounding the part A becomes less apparent. Accordingly, the uniform brightness is attained and a design of the lamp unit is further improved.  
         [0036]     The square pyramid-shaped prism lenses P disposed at the rear surface of the cover lens  30  diffuse and emit the light from the lamp L. This arrangement provides a high grade lighting.  
         [0037]     When the lamp bezel  20  has the through-holes  25 , which are formed when the attachment portions  24  are manufactured, outside the part A, the through-holes  25  are visible through the cover lens  30  and reduce a design of the room lamp. In the present invention, the through-holes  25  are covered with the opaque covers  50  which are covered with the cover lens  30  so that the through-holes  25  are not visible from the front side of the cover lens  30  and the design of the room lamp is improved. As shown in  FIG. 3 , the opaque covers  50  prevent dusts or water from entering into the cover lens  30  through the through-holes  25  and protect the cover lens  30  from dirt and burning.  
         [0038]     When the sliding member  40  does not cover the sliding grooves  23  in the conventional room lamp, the sliding grooves  23  disposed outside the part A are visible through the cover lens  30 . In the embodiment of the present invention, the sliding member  40  always covers all over the sliding grooves  23  irrespective of the location of the sliding member  40  so that the sliding grooves  23  disposed outside the part A are not visible from the front side of the cover lens  30 . This arrangement improves the design of the room lamp. The sliding grooves  23  are covered with the sliding member  40  without other member so that the sliding member  40  is moved without interference. This results in an easy assembly and low cost manufacturing.  
         [0039]     Since the sliding member  40  is formed to extend into Y 1  direction to be overlapped to the opaque covers  50 , the sliding member  40  supports the opaque covers  50  when the opaque covers  50  are unlocked and dropped off. Then, when the cover lens  30  is removed for a maintenance of the room lamp, the opaque covers  50  do not drop off.  
         [0040]     It is not necessary to attach the opaque covers  50  to the lamp bezel  20  when the through-holes  25  are not formed or a small size.  
         [0041]     The cover lens  30  can be embossed all over the area thereof. In this case, the part A is embossed densely than the area outside the part A to reduce the light transmittance at the part A.  
         [0042]     The light transmittance at an area, through which the through-holes  25  and the sliding grooves  23  are visible, can be reduced compared to the outside area.