Abstract:
An illuminating device ( 10 ) includes an LED ( 11 ) and a light guiding plate ( 13 ). The light guiding plate includes a light incident surface ( 136 ) and a light output surface ( 132 ). The LED faces toward the light input surface. The light guiding plate defines a plurality of recesses ( 133 ) therein. A fluorescent material ( 15 ) is applied to the light guiding plate. The LED is used to emit first light of a first wavelength to excite the fluorescent material thereby producing second light of a second wavelength. The LED and the fluorescent material are arranged in a manner that the combined first and second light emitted from the light output surface appears to be white light.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is related to a co-pending application entitled a same title with the present application, assigned to the same assignee of this application and filed on the same date. The disclosure of the co-pending application is wholly incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present invention generally relates to illuminating devices, and particularly to an illuminating device incorporating light emitting diodes (LEDs) used for reducing glare generated by the illuminating device. 
         [0004]    2. Description of Related Art 
         [0005]    With the continuing development of scientific technology, LEDs have been widely used in illumination devices to substitute for conventional cold cathode fluorescent lamps (CCFL) due to their high brightness, long lifespan, and wide color gamut. Relevant subject matter is disclosed in an article entitled “Solid State Lighting: Toward Superior Illumination”, published in a magazine Proceedings of the IEEE, Vol. 93, No. 10, by Michael S. Shur et al. in October, 2005, the disclosure of which is incorporated herein by reference. 
         [0006]    However, glare generated by the illuminating devices is an intense and blinding light, which is harmful to people&#39;s eyes. 
         [0007]    Therefore, what is needed is a new illuminating device, which can reduce the glare generated by the illuminating device. 
       SUMMARY 
       [0008]    The present invention relates to an illuminating device. According to an exemplary embodiment, the illuminating device includes an LED and a light guiding plate. The light guiding plate includes a light incident surface and a light output surface. The LED faces toward the light input surface. The light guiding plate defines a plurality of recesses therein. A fluorescent material is applied to the light guiding plate. The LED is used to emit first light of a first wavelength to excite the fluorescent material thereby producing second light of a second wavelength. The LED and the fluorescent material are arranged in a manner that the combined first and second light emitted from the light output surface appears to be white light. 
         [0009]    Other advantages and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Many aspects of the present illuminating device 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 illuminating device. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
           [0011]      FIG. 1  is a schematic, cross-sectional view of an illuminating device in accordance with a first embodiment of the present invention. 
           [0012]      FIG. 2  is a schematic, cross-sectional view of an illuminating device in accordance with a second embodiment of the present invention. 
           [0013]      FIG. 3  is a schematic, cross-sectional view of an illuminating device in accordance with a third embodiment of the present invention. 
           [0014]      FIG. 4  is a schematic, cross-sectional view of an illuminating device in accordance with a forth embodiment of the present invention. 
           [0015]      FIG. 5  is a schematic, cross-sectional view of an illuminating device in accordance with a fifth embodiment of the present invention. 
           [0016]      FIG. 6  is a schematic, cross-sectional view of an illuminating device in accordance with a sixth embodiment of the present invention. 
           [0017]      FIG. 7  is a schematic, cross-sectional view of an illuminating device in accordance with a seventh embodiment of the present invention. 
           [0018]      FIG. 8  is a schematic, cross-sectional view of an illuminating device in accordance with a eighth embodiment of the present invention. 
           [0019]      FIG. 9  is a schematic, cross-sectional view of an illuminating device in accordance with a ninth embodiment of the present invention. 
           [0020]      FIG. 10  is a schematic, cross-sectional view of an illuminating device in accordance with a tenth embodiment of the present invention. 
           [0021]      FIG. 11  is a schematic, cross-sectional view of an illuminating device in accordance with an eleventh embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Referring to  FIG. 1 , an illuminating device  10  in accordance with a first embodiment of the present invention includes a light emitting component, a light guiding plate  13  and a fluorescent material  15 . In the present embodiment, the light emitting component is an LED  11 . 
         [0023]    The LED  11  is disposed at a lateral side of the light guiding plate  13 , for serving as a primary light source. 
         [0024]    The plate  13  is made of transparent materials, such as silicone, resin, glass, polymethyl methacrylate (PMMA), quartz, polycarbonate (PC), epoxy, polyacrylate and so on. The plate  13  has light transparency of 70% and refractive index of 1.4-1.7. The plate  13  has a rectangular shape. The plate  13  includes a light incident surface  136 , a light output surface  132  and a bottom surface  137  opposite to the light output surface  132 . The light incident surface  136  faces toward the LED  11 . A light reflective layer  131  is evenly disposed on the bottom surface  137 , so as to reflect the light emitted from the LED  11  toward the light output surface  132 . It should be understood that the light reflective layer  131  can be disposed on both of the bottom surface  137  and a lateral side surface opposite to the light incident surface  136 . 
         [0025]    The plate  13  defines a plurality of tiny recesses  133  in the light output surface  132  thereof. The recesses  133  are spaced from each other and evenly defined in the light output surface  132 . Each recess  133  has a strip shape from a front end toward a rear end. A width of each recess  133  at a topmost end thereof is less than 5 mm. Each recess  133  includes two slanted sidewalls  135  (only one sidewall is labeled) opposite to each other. Each sidewall  135  is a planar surface. It should be understood that the sidewall  135  can be a curved surface, such as a paraboloid and so on. The recesses  133  can coarsen the slippery light output surface  132  of the plate  13 , thereby preventing total reflection of light at the light output surface  132 . Thus, the light can easily enter the light output surface  132 , and exit out of the plate  13 . In addition, the recesses  133  can minimize an incident angle of the light with respect to the light output surface  132 , which enables the light to form an irregular reflection at the light output surface  132 . Accordingly, the light is emitted out of the light output surface  132  along different directions thus it is evenly distributed. It should be understood that the sidewalls  135  of the recesses  133  can be rough, thereby further enables the light to form an irregular reflection at the light output surface  132 . 
         [0026]    The recesses  132  in the light output surface  132  can be made by micro electro mechanical system (MEMS), injection molding, micro electroforming, lithography, etching and so on. 
         [0027]    The fluorescent material  15  can be made of sulfide, aluminate, oxide, silicate or nitride, such as Ca 2 Al 12 O 19 :Mn, (Ca, Sr, Ba)Al 2 O 4 :Eu, Y 3 Al 5 O 12 :Ce 3+ (YAG), Tb 3 Al 5 O 12 :Ce 3+ (TAG), BaMgAl 10 O 17 :Eu 2+ (Mn 2+ ), Ca 2 Si 5 N 8 : Eu 2+ , (Ca,Sr,Ba)S:Eu 2+ , (Mg, Ca, Sr, Ba) 2 SiO 4 :Eu 2+ , (Mg, Ca, Sr, Ba) 3 Si 2 O 7 :Eu 2+ , Ca 8 Mg(SiO 4 ) 4 Cl 2 :Eu 2+ , Y 2 O 2 S:Eu 3+ , (Sr, Ca, Ba)Si x O y Nz:Eu 2+ , (Ca, Mg, Y)SiwAl x O y N z :Eu 2+ , CdS and so on. 
         [0028]    The fluorescent material  15  is received in the recesses  133  in the light output surface  132 , for serving as a secondary light source. A combination of the fluorescent material  15  and the LED  11  is selected from a group consisting of yellow fluorescent material and blue LED; red and green fluorescent material and blue LED; red, green and blue fluorescent material and ultraviolet LED. The fluorescent material  15  is excited by a part of the light emitted from the LED  11  and emits divergent light along different directions. The light from the fluorescent material  15  is mixed together with the other part of the light emitted from the LED  11  to generate white light. 
         [0029]    Before being received in the recesses  135 , the fluorescent material  15  is mixed together with a liquid-state colloid, such as resin, epoxy, silicone and so on. The mixed fluorescent material  15  is filled into the recesses  135 , and then solidified via heating or ultraviolet. The fluorescent material  15  mixed together with the colloid can prevent the fluorescent material  15  from contacting with outside atmosphere as possible as it can. Thus, the fluorescent material  15  is isolated from the outside atmosphere and can not metamorphose due to contact with the outside atmosphere. 
         [0030]    When the illuminating device  10  operates, the light emitted from the LED  11  enters into the plate  13  through the light incident surface  136 . A part of the light entering into the plate  13  directly emits toward the light output surface  132  of the plate  13 . The other part of the light entering into the plate  13  emits toward the bottom surface  137 , and is reflected by the light reflective layer  131 . The light reflected by the light reflective layer  131  changes its original direction, and emits toward the light output surface  132  of the plate  13 . A part of the light arrived at the light output surface  132  exits the plate  13  at a non-recess position of the light output surface  132 . Another part of the light arrived at the light output surface  132  is refracted through the slanted sidewalls  135  of the recesses  133 , and emits toward the fluorescent material  15  in the recesses  133 . The fluorescent material  15  is accordingly excited by the light and emits divergent light which exits the plate  13  along different directions. The other part of the light arrived at the light output surface  132  is further reflected by the light output surface  132  and the light reflective layer  131 , and finally emits toward the fluorescent material  15  in the recesses  133 . The fluorescent material  15  is accordingly excited and emits divergent light which exits the plate  13  along different directions. 
         [0031]    In the illuminating device  10 , the LED  11  is disposed adjacent to the light incident surface  136  of the plate  13 , and the fluorescent material  15  is received in the recesses  133  of the plate  13 . Namely, the LED  11  is in a distance away from the fluorescent material  15 , which can prevent the fluorescent material  15  from overheating. Accordingly, the lifespan and the performance of the illuminating device  10  can be improved. In addition, the recesses  133  of the plate  13  can prevent total reflection of light at the light output surface  132  as possible as it can, thereby improving the utilization rate of the light. Furthermore, the fluorescent material  15  is received in the recesses  133  in the light output surface  132 , whereby the fluorescent material  15  is excited by the light and emits divergent light exiting the plate  13  along different directions. Accordingly, the light can evenly distribute on the light output surface  132 , which can reduce glare, thus making the light feel more comfortable to the user&#39;s eyes. 
         [0032]    Moreover, the fluorescent material  15  is excited by a part of the light emitted from the LED  11  to emit light. The light emitted from the fluorescent material  15  has a different wavelength from the light emitted from the LED  11 . The light emitted from the fluorescent material  15  mixes together with the other part of the light emitted from the LED  11  to generate white light at the light output surface  132 . The white light is favorable to be used in illumination field. Specially, the wavelength of the light emitted from the fluorescent material  15  is greater than that of the light emitted from the LED  11 . 
         [0033]    It should be understood that the LED  11  is not limited to the above-described location. Referring to  FIG. 2 , in the illuminating device  20  of the second embodiment, the LED  21  is received in the plate  23 . The LED  21  is embedded in a lateral side of the plate  23 , and is in a distance away from the fluorescent material  15 . The light incident surface  236  is formed at a position of the plate  13  facing toward the LED  21 . 
         [0034]    It should be understood that the recesses  133  in the illuminating device  10 ,  20  can also have other arrangements and configurations, as shown in the following embodiments. 
         [0035]    Referring to  FIG. 3 , an illuminating device  30  in accordance with a third embodiment of the present invention is shown. The illuminating device  30  is similar to the illuminating device  10  in the first embodiment. In the present embodiment, the recesses  333  in the light output surface  332  of the plate  33  are contiguous with each other. A transmitting manner of the light in the illuminating device  30  is similar to that in the illuminating device  10 . 
         [0036]    Referring to  FIG. 4 , an illuminating device  40  in accordance with a forth embodiment of the present invention is shown. The illuminating device  40  is similar to the illuminating device  30  in the third embodiment. In the present embodiment, the recesses  433  in the light output surface  432  of the plate  43  have a depth gradually increasing in a direction away from the LED  11 . An incident angle of the light emitted toward the recess  433  remote from the LED  11  is greater than that the light emitted toward the recess  433  adjacent to the LED  11 , so that the light emitted toward the recess  433  remote from the LED  11  can generate total reflection easily. The recesses  433  having increased depth can prevent the light from generating total reflection. A transmitting manner of the light in the illuminating device  40  is similar to that in the illuminating device  10 . 
         [0037]    Referring to  FIG. 5 , an illuminating device  50  in accordance with a fifth embodiment of the present invention is shown. The illuminating device  50  is similar to the illuminating device  40  in the forth embodiment. In the present embodiment, the recesses  533  are defined in the bottom surface  537  of the plate  53 . 
         [0038]    During operation, the light emitted from the LED  11  enters into the plate  53  through the light incident surface  136 . A part of the light entering into the plate  53  directly emits toward the light output surface  132  of the plate  53 . The other part of the light entering into the plate  53  directly emits toward the bottom surface  537  of the plate  53 , or is reflected by the light output surface  132  and emits toward the bottom surface  537 . 
         [0039]    The light arrived at the bottom surface  537  is refracted through the slanted sidewalls  135  of the recesses  533 , and emits toward the fluorescent material  15  in the recesses  533 . The fluorescent material  15  is accordingly excited by the light and emits divergent light along different directions. A part of the light emitted from the fluorescent material  15  directly emits toward the light output surface  132  of the plate  53 . The other part of the light emitted from the fluorescent material  15  is reflected by the light reflective layer  131 , and emits toward the light output surface  132  of the plate  53 . 
         [0040]    A part of the light arrived at the light output surface  132  directly exits the plate  53  through the light output surface  132 . The other part of the light arrived at the light output surface  132  is reflected by the light output surface  132 , and emits toward the recesses  533  on the bottom surface  537 . The fluorescent material  15  in the recesses  533  is accordingly excited by the light and emits divergent light along different directions. As a result, the light emitted from the fluorescent material  15  exits the plate  15  along different directions at the light output surface  132  after further reflection by the light output surface  132  or/and the light reflective layer  131 . 
         [0041]    Referring to  FIG. 6 , an illuminating device  60  in accordance with a sixth embodiment of the present invention is shown. The illuminating device  60  is similar to the illuminating devices  40 ,  50  in the forth and fifth embodiment. In the present embodiment, the recesses  633  are defined in both of the light output surface  632  and the bottom surface  637  of the plate  63 . A transmitting manner of the light in the illuminating device  60  is similar to that in the illuminating device  10 ,  50 . 
         [0042]    It should be understood that the fluorescent material  15  in the illuminating device  10 ,  20 ,  30 ,  40 ,  50 ,  60  can also have other arrangements, as shown in the following embodiments. 
         [0043]    Referring to  FIG. 7 , an illuminating device  70  in accordance with a seventh embodiment of the present invention is shown. The illuminating device  70  is similar to the illuminating device  10  in the first embodiment. In the present embodiment, the fluorescent material  75  is evenly distributed on the bottom surface  737  of the plate  73  and spaced from each other. In other words, the fluorescent material  75  is sandwiched between the bottom surface  737  and the light reflective layer  131  of the plate  73 . The fluorescent material  75  is formed on the bottom surface  737  via imprint technics and so on. 
         [0044]    The light emitted from the LED  11  emits toward the fluorescent material  75  on the bottom surface  737 , and activates the fluorescent material  75  to emit divergent light along different directions. The light emitted form the fluorescent material  75  emits toward the light output surface  732 , and exits the plate  73  after refraction through the recesses  133 . 
         [0045]    Referring to  FIG. 8 , an illuminating device  80  in accordance with an eighth embodiment of the present invention is shown. The illuminating device  80  is similar to the illuminating device  70  in the seventh embodiment. In the present embodiment, the fluorescent material  85  is further discretely received in the recesses  833  in the light output surface  832  of the plate  83 . 
         [0046]    Referring to  FIG. 9 , an illuminating device  90  in accordance with a ninth embodiment of the present invention is shown. In the present embodiment, the illuminating device  90  includes a light guiding plate  93 , a plurality of LEDs  91  and a plurality of light coupling portions  97 . 
         [0047]    The plate  93  includes a light incident surface  931  at a top end thereof and a light output surface  932  opposite to the light incident surface  931 . The plate  93  defines a plurality of tiny recesses  933  in the light output surface  932  thereof. The recesses  933  are contiguous with each other and evenly defined in the light output surface  932 . A fluorescent material  95  is received in the recesses  933 . The materials made of the fluorescent material  95  is the same as that made of the fluorescent material  15  in the first embodiment. The fluorescent material  95  is excited by a part of the light emitted from the LEDs  91  and emits divergent light along different directions. The light from the fluorescent material  95  is mixed together with the other part of the light emitted from the LEDs  91  to generate a white light. 
         [0048]    The light coupling portions  97  have one-to-one corresponding relationships with respect to the LEDs  91 . Each light coupling portion  97  has a truncated conical shape, and tapers from a bottom end to a top end thereof. Each light coupling portion  97  includes a light incident coupling surface  971  at the top end thereof, a light output coupling surface  972  at the bottom end thereof, and a slanted light reflective surface  973  interconnecting with the incident coupling surface  971  and the output coupling surface  972 . The incident coupling surface  971  is disposed adjacent to the corresponding LED  91 . The output coupling surface  972  faces toward the light incident surface  931  of the plate  93 . The light coupling portions  97  are made of transparent materials, such as silicone, resin and so on. The light coupling portions  97  has light transparency of 70% and refractive index of 1.4-1.7. 
         [0049]    During operation, the light emitted from the LED  91  enters into the corresponding light coupling portion  97  through the incident coupling surface  971 . A part of the light entering into the light coupling portion  97  directly exits the light coupling portion  97  through the output coupling surface  972 . The other part of the light entering into the light coupling portion  97  is total reflected by the light reflective surface  973 , changing its original direction, and exits the light coupling portion  97  through the output coupling surface  972 . The light exiting the light coupling portion  97  enters into the plate  93  through the incident coupling surface  931 . The light entering into plate  93  emits toward the light output surface  932 . The light arrived at the light output surface  932  is refracted through the slanted sidewalls  935  of the recesses  933 , and emits toward the fluorescent material  95  in the recesses  933 . The fluorescent material  95  is accordingly excited by the light and emits divergent light exiting the plate  93  along different directions. 
         [0050]    Referring to  FIG. 10 , an illuminating device  90   a  in accordance with a tenth embodiment of the present invention is shown. The illuminating device  90   a  is similar to the illuminating device  90  in the ninth embodiment. In the present embodiment, the plate  93   a  includes a plurality of cavities  934 , a fluorescent material  938  and a dielectric material  939 . 
         [0051]    The cavities  934  are irregularly distributed in an inside of the plate  93   a  from the incident coupling surface  931  to the light output surface  932 . The plate  93   a  is irradiated by electromagnetic wave having high energy density. As a result, an inner structure of the plate  92   a  is destroyed, so as to form the cavities  934 . 
         [0052]    The fluorescent material  938  and the dielectric material  939  are irregularly distributed in the inside of the plate  93   a . The material made of the fluorescent material  938  is the same as that made of the fluorescent material  95 . The dielectric material  939  is made of Al 2 O 3 , TiO 2 , SiO 2 , SiN x , CaF 2 , BaSO 4 , ZnO, B 2 O 3 , Nb 2 O, Na 2 O or Li x O y  and so on. The dielectric material  939  enables the light entering into the plate  93   a  to scatter, which is favorable to make the light evenly distribute on the light output surface  932 . 
         [0053]    During operation, the light emitted from the LED  91  passes through the corresponding light coupling portion  97 , and enters into the plate  93   a . A part of the light entering into plate  93   a  directly emits toward the recesses  933  in the light output surface  932 . Another part of the light entering into plate  93   a  emits toward the dielectric material  939 , changing its original direction and emitting toward the recesses  933  in the light output surface  932 . The other part of the light entering into plate  93   a  emits toward the fluorescent material  938 . The fluorescent material  938  is accordingly excited by the light, and emits divergent light along different directions toward the recesses  933  in the light output surface  932 . The light emitting toward the recesses  933  in the light output surface  932  is refracted through the slanted sidewalls  935  of the recesses  933 , and emits toward the fluorescent material  95  in the recesses  933 . The fluorescent material  95  is accordingly excited by the light, and emits divergent light exiting the plate  93   a  along different directions. 
         [0054]    Referring to  FIG. 11 , an illuminating device  90   b  in accordance with an eleventh embodiment of the present invention is shown. The illuminating device  90   b  is similar to the illuminating device  90   a . In the present embodiment, there is no recess in the light output surface  932   b  of the plate  93   b.    
         [0055]    During operation, the light emitted from the LED  91  passes through the corresponding light coupling portion  97 , and enters into the plate  93   b . A part of the light entering into plate  93   b  is directly refracted through the light output surface  932   b  out of the plate  93   b . Another part of the light entering into plate  93   b  emits toward the dielectric material  939 , changing its original direction, and exits the plate  93   b  through the light output surface  932   b . The other part of the light entering into plate  93   b  emits toward the fluorescent material  938 . The fluorescent material  938  is accordingly excited by the light, and emits divergent light exiting the plate  93   b  along different directions. 
         [0056]    Alternatively, the light coupling portion  97  can be detachably engaged with the plate  93 ,  93   a ,  93   b , or integrally formed with the plate  93 ,  93   a ,  93   b  as a single piece. 
         [0057]    It is believed that the present invention and its 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 invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.