Abstract:
An exemplary anti-glare indoor lamp includes a shade, light source, and an optical sheet. The shade defines a receiving cavity therein and an opening at the bottom of the receiving cavity. The light source is received in the receiving cavity and positioned to emit light toward the opening. The optical sheet is arranged facing the opening and is sized to cover only part of the opening. The optical sheet is configured for reducing the brightness of the light passing therethrough, and is movable to cover a selected part of the opening. Therefore, the light reaching eyes of a user is reduced, and glare is avoided or at least mitigated.

Description:
BACKGROUND 
     1. Technical Field 
     The present invention relates to lamps, and particularly to an indoor lamp with anti-glare function. 
     2. Description of Related Art 
     Lamps have numerous applications. Indoor lamps are used for a variety of purposes, such as illuminating a book that one wants to read. 
     Generally, visible light emitted from a lamp falls within a particular luminance range. When the luminance of the light is too low, visibility is impaired. On the other hand, when the luminance is too high, glare also limits visibility. In the latter case, the light may also cause discomfort or pain. Glare can also occur when light reflects from a target object to a person. In this situation, the occurrence of glare varies according to both the amount of luminance and the relative positions of the light source, the target object and the person. Considerable research has been carried out regarding elimination of glare. 
     An indoor lamp which provides good luminance without glare is desired. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present embodiments. Moreover, in the drawings, all the views are schematic, and like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is an isometric view of a first embodiment of an indoor lamp, showing the indoor lamp inverted. 
         FIG. 2  is a side plan view of the indoor lamp of  FIG. 1  together with a desktop and a user, showing optical paths of a light source of the indoor lamp, the optical paths relating to anti-glare function. 
         FIG. 3  is similar to  FIG. 2 , but showing the situation in respect of a second embodiment of an indoor lamp. 
         FIG. 4  is an isometric view of a third embodiment of an indoor lamp, showing the indoor lamp inverted. 
         FIG. 5  is an isometric view of a fourth embodiment of an indoor lamp. 
         FIG. 6  is an isometric view of a fifth embodiment of an indoor lamp. 
         FIG. 7  is an isometric view of a sixth embodiment of an indoor lamp. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , an indoor lamp  10  of a first exemplary embodiment includes a light source  12 , a shade  14  and an anti-glare member  16 . The indoor lamp  10  has anti-glare function. 
     The light source  12  can be a single light emitting diode (LED), an LED array, a fluorescent lamp, an incandescent lamp, a gas discharge lamp, or a halogen lamp. In other embodiments, there can be a plurality of light sources  12 . 
     The shade  14  is generally dome-like or cup-like in shape, and tapers in profile from bottom to top. The shade  14  defines a receiving cavity  140  therein. The light source  12  is installed in the receiving cavity  140 . The shade  14  has a round opening  142  at the bottom of the receiving cavity  140 . A flange portion  14 A is formed on an outer surface of a bottom end of the shade  14 . The flange portion  14 A is annular, and surrounds the round opening  142 . 
     Referring also to  FIG. 2 , the anti-glare member  16  includes a hooked member  162  and an optical sheet  164 . The hooked member  162  includes a generally U-shaped portion  1622  and a connection portion  1624 . The U-shaped portion  1622  is configured for slidably engaging with the flange portion  14 A. That is, the U-shaped portion  1622  is slidable along the flange portion  14 A. 
     The U-shaped portion  1622  extends from an outer side of the connection portion  1624 . Preferably, the connection portion  1624  is integrally formed with the U-shaped portion  1622 , with the U-shaped portion  1622  and the connection portion  1624  being parts of a single continuous body of material. The connection portion  1624  is parallel to and faces the round opening  142 . An inner side of the connection portion  1624  is connected with the optical sheet  164 . The position of the optical sheet  164  in the round opening  142  can be changed by sliding the U-shaped portion  1622  along the flange portion  14 A. 
     The optical sheet  164  has an area less than that of the round opening  142 . In the illustrated embodiment, a diameter of the optical sheet  164  is less than half a diameter of the round opening  142 . The optical sheet  164  is parallel to and faces the round opening  142  and covers a region M thereof. The region of the round opening  142  not covered by the optical sheet  164  is defined as a region N. In this embodiment, the optical sheet  164  is a diffuser. 
     The indoor lamp  10  is used, for example, with a desktop  200 . The indoor lamp  10  is positioned over the desktop  200 , and the optical sheet  164  faces the desktop  200 . Light emitted from the light source  12  does not directly reach the eyes of a user  202  due to the shade  14 . The light emitted from the light source  12  passes through the regions M and N and is then reflected by the desktop  200 . In this embodiment, the optical sheet  164  is positioned at a side of the shade  14  adjacent to the user  202 . 
     As shown by the dashed portion of the line I in  FIG. 2 , in the case where no optical sheet  164  is included in the indoor lamp  10 , the light emitted from the light source  12  passes through the region M and is reflected to the eyes of the user  202  by the desktop  200 . If the light emitted from the light source  12  is bright, the user  202  is liable to experience glare and accompanying discomfort. As indicated by the continuous line II in  FIG. 2 , when the optical sheet  164  is included in the indoor lamp  10 , the light emitted from the light source  12  passes through region M and is diffused by the optical sheet  164 . Thus the brightness of the light reflected by the desktop  200  to the user  202  is reduced, and glare is avoided or at least mitigated. Light passing through the region N is unaltered, and directly illuminates the desktop  200  and surroundings. 
     Additionally, when the position of the user  202  changes relative to the indoor lamp  10 , the position of the optical sheet  164  can be changed accordingly by sliding the U-shaped portion  1622  along the flange portion  14 A. For improved anti-glare function, a transmission rate of the optical sheet  164  may be less than 80%, and even less than 60%. An annular end face  144  of the shade  14  at the flange portion  14 A defines a reference plane  146 . In the illustrated embodiment, the light source  12  is installed in the receiving cavity  140  such that a center axis of the light source  12  is coaxial with a center axis III of the shade  14 . The center axis III is perpendicular to the reference plane  146 . An angle θ is defined between the center axis III and the continuous portion of the line I. The optical sheet  164  provides effective anti-glare function when the angle θ is in the range from 30° to 75°. 
     It is to be understood that in alternative embodiments, the optical sheet  164  can be a reflector or a light filter. The light filter can be a neutral density filter or a bandpass filter. The bandpass filter can filter out light with a wavelength in the range from 410 nanometers (nm) to 780 nm. In other alternative embodiments, the optical sheet  164  can be a sheet with an anti-dazzling function. 
     Referring to  FIG. 3 , this shows an indoor lamp  30  of a second exemplary embodiment. The indoor lamp  30  differs from the indoor lamp  10  as follows. A hooked member (not labeled) has a very small connection portion or no connection portion at all. An optical sheet  36  has a diameter that is substantially half a diameter of a round opening (not labeled). A bottom of the optical sheet  36  includes a plurality of parallel prisms. The prisms are spaced apart from one another. Each of the prisms is generally parallel to an imaginary chord defined by a hooked member (not labeled) of the anti-glare member. Each prism is a triangular prism. A side of each prism farthest from a center axis (not labeled) of the shade  14  is substantially parallel to the center axis of the shade  14 . Another side of each prism nearest to the center axis of the shade  14  is oblique to the center axis of the shade  14 . Light emitted from the light source  12  is refracted by the prisms and thereby deflected from its original paths. Therefore, the light reflected by the desktop  200  to the eyes of the user  202  is reduced, and glare is avoided or at least mitigated. 
     Referring to  FIG. 4 , this shows an indoor lamp  40  of a third exemplary embodiment. The indoor lamp  40  differs from the indoor lamp  10  as follows. The hooked member  162  is omitted. The indoor lamp  40  includes a light-pervious cover  43 , which has a generally spherical curvature. An imaginary longest chord of the light-pervious cover  43  has a length substantially the same as the diameter of the round opening  142 . That is, a circumference of the light-pervious cover  43  is substantially the same as that of the round opening  142 . The wall of the shade  14  at the round opening  142  and the light-pervious cover  43  abut each other, with the interface therebetween being sealed. The sealing may be achieved by, e.g., interference fit or applied transparent adhesive. Thereby, the light-pervious cover  43  is fixed to the wall of the shade  14 . The light-pervious cover  43  is configured for optically adjusting, that is diverging or converging, the paths of light emitted from the light source  12 , and thus adjusting an illumination scope of the light source  12 . In the illustrated embodiment, the light-pervious cover  43  is in the form of a meniscus lens that converges the paths of light emitted from the light source  12 . The optical sheet  164  is detachably attached to a bottom surface of the light-pervious cover  43 , such that a position of the optical sheet  164  relative to the light-pervious cover  43  can be changed according to the position of the user  202 . The detachably attaching may be achieved by. e.g., applied transparent undry-glue. 
       FIG. 5  is a schematic, isometric view of an indoor lamp  40  of a fourth exemplary embodiment. The indoor lamp  40  differs from the indoor lamp  10  as follows: 
     A shade  54  and a light source  52  of the indoor lamp  50  have elongated structures. The shade  54  has a generally U-shaped cross section, with two elongated free ends  544 . In the illustrated embodiment, the shade  54  has a generally semi-elliptical cross section. An elongated rectangular opening  542  is defined between the two free ends  544 . Two straight flange portions  54 A are formed on an outer wall of the shade  54  at the two free ends  544 , respectively. The flange portions  54 A are parallel with each other, and extend from the two free ends  544  in opposite directions away from each other. Two hooked members  58  are connected with two opposite ends of a flat optical sheet  56 , respectively. The hooked members  58  are slidably connected with the two flange portions  54 A, respectively, in a manner similar to that of the hooked member  162  slidably connecting with the flange portion  14 A. However, the hooked members  58  are straight along lengths thereof that are parallel to the flange portions  54 A. With this arrangement, the optical sheet  56  is parallel to and faces the opening  542 . A transverse width of the optical sheet  56  measured parallel to a longitudinal axis of the opening  542  is less than a corresponding length of the opening  542 . 
     Referring to  FIG. 6 , this shows an indoor lamp  60  of a fifth exemplary embodiment. The indoor lamp  60  differs from the indoor lamp  50  as follows. The indoor lamp  60  further includes a light-pervious cover  63  connected with a shade  64 . The light-pervious cover  63  is between a curved optical sheet  66  and a light source  62 . The light-pervious cover  63  covers an entire elongated, rectangular opening  642 , and has a curved cross section matching that of the optical sheet  66 . In the illustrated embodiment, both the light-pervious cover  63  and the optical sheet  66  are curved convexly, and the optical sheet  66  slidably abuts but is spaced from an outer surface of the light-pervious cover  63 . 
     Referring to  FIG. 7 , this shows an indoor lamp  70  of a sixth exemplary embodiment. The indoor lamp  70  differs from the indoor lamp  50  in that two elongated flange portions  74 A are curved along respective lengths thereof. In the illustrated embodiment, the curvature of each elongated flange portions  74 A is an arc shape. Each of two hooked members  78  is curved along a length thereof that corresponds to a length of the respective flange portion  74 A, with the curvature of the hooked member  78  matching the curvature of the flange portion  74 A. 
     It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the disclosure or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the disclosure.