Abstract:
An exemplary illuminating apparatus includes a light source, a supporting member, a first film and a second film. The light source includes a substrate and a plurality of light emitting diode arranged on the substrate. The supporting member connected to the substrate. The supporting member includes a light emitting surface at a side thereof distant from the light emitting diodes. The first film and the second film attached to each other and arranged at the light emitting surface of the supporting member. The first film includes a first phosphor doped therein, and the second film includes a second phosphor doped therein. Each of the first phosphor and the second phosphor is capable of being excited by light emitted from the light-emitting diodes and converting a wavelength of the light into a desired wavelength.

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure generally relates to illuminating apparatuses, and particularly to an illuminating apparatus with a light emitting diode and phosphor films for emitting different colors of light. 
     2. Discussion of Related Art 
     Light emitting diodes (LEDs) are one kind of semiconductor element. Nowadays, LEDs are extensively used as light sources for illuminating apparatuses, due to their high luminous efficiency, low power consumption and long work life. 
     In some LED devices, to satisfy certain illuminating requirements, light mixing is employed. That is, light with different colors or wavelengths is emitted from different light emitting diodes, and such light is mixed to form light of a desired color or wavelength. For example, white light is obtained by mixing light emitted by red, green, and blue LED dies. However, because these three LED dies cannot occupy the same position in the LED device and must be arranged adjacent to each other, the light mixing is not necessarily thorough, and the light output from the LED device may be non-uniform. Alternatively, a light source module may use a blue LED as a primary light source to produce a final emission of white light. The blue light emitted from the blue LED strikes phosphor material of the light source module to generate secondary yellow color light. The combination of the yellow light and residual (unconverted) blue light produces white light. However, the phosphor is usually packaged within the blue LED itself. It is difficult to ensure that the phosphor is evenly distributed in the LED. If the phosphor is unevenly distributed, the light output from the light source module may be non-uniform. 
     Therefore, what is needed is an illuminating apparatus to overcome the above described shortcomings. 
    
    
     
       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 a cross-sectional view of an illuminating apparatus, according to a first exemplary embodiment. 
         FIG. 2  is a cross-sectional view of an illuminating apparatus, according to a second exemplary embodiment. 
         FIG. 3  is a cross-sectional view of an illuminating apparatus, according to a third exemplary embodiment, showing an arrangement of first regions of a first film and second regions of a second film. 
         FIG. 4  is similar to  FIG. 3 , but showing a variation of the third exemplary embodiment, in which the first regions of the first film and the second regions of the second film have a different arrangement. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Reference will now be made to the drawings to describe various embodiments of the present illuminating apparatus in detail. 
     Referring to  FIG. 1 , an illuminating apparatus  100 , in accordance with a first exemplary embodiment, includes a light source  11 , a supporting member  12 , a first film  13 , and a second film  14 . 
     The light source  11  includes a substrate  111 , and a plurality of light emitting diodes (LEDs)  112  arranged on an inner side of the substrate  111 . In the present embodiment, the LEDs  112  are ultraviolet LEDs. 
     In this embodiment, the supporting member  12  has a generally U-shaped cross section. A main, central portion of the supporting member  12  is in the form of, or includes, an optical lens  123 . The optical lens  123  is plate-shaped and parallel to the substrate  111 , and has a flat surface  121 . The supporting member  12  is arranged on the inner side of the substrate  111  and engaged with a periphery of an underside of the substrate  111 . Thereby, the substrate  111  and the supporting member  12  cooperatively define a cavity therebetween. The LEDs  112  are located in the cavity. Light emitted from the LEDs  112  transmits through the optical lens  123  and emits from the optical lens  123  through the flat surface  121 . 
     The first film  13  is attached on the flat surface  121  of the optical lens  123 , and is doped with a first phosphor  131 . In the present embodiment, the first film  13  is a planar film. 
     The second film  14  is attached to an outer side of the first film  13 , and is doped with a second phosphor  141 . In the present embodiment, the second film  14  is a planar film. The first film  13  or the second film  14  having thickness at least more than 100 micron (um). In an alternative embodiment, the second film  14  can be attached to an inner side of the first film  13 . 
     The first film  13  and the second film  14  may be made of silicone, polymethyl methacrylate (PMMA), resin, plastic, polyethylene terephthalate (PET), or polycarbonate (PC). 
     In the present embodiment, each of the first phosphor  131  and the second phosphor  141  is in the form of a multiplicity of particles. Sizes of the particles can be in the range from 20 nanometers (nm) to 40 um. The first phosphor  131  and the second phosphor  141  may be made of sulfides, aluminates, oxides, silicates, or nitrides. For example, the first phosphor  131  and the second phosphor  141  can be selected from Ca 2 Al 12 O 19 :Mn, (Ca,Sr,Ba)Al 2 O 4 :Eu, CdS, Ca 2 Si 5 N 8 :Eu 2+ , Y 3 A 15 O12Ce 3+ (YAG), Tb 3 Al 5 O 12 :Ce 3+ (YAG), CdTe, (Mg,Ca,Sr,Ba) 2 SiO 4 :Eu 2+ , (Ca,Mg,Y)SiwAl x O y N z :Eu 2+ , Y 2 O 2 S:Eu 3+ , (Mg,Ca,Sr,Ba) 3 Si 2 O 7 :Eu 2+ , (Ca,Sr,Ba)S:Eu 2+ , Ca 8 Mg(SiO 4 ) 4 Cl 2 :Eu 2+ , BaMgAl 10 O 17 :Eu 2+ (Mn 2+ ), (Sr,Ca,Ba)Si x O y N z :Eu 2+ , and/or CdSe. 
     The first phosphor  131  and the second phosphor  141  are excited by the light emitted from the LEDs  112 , and convert the wavelength of such light. In the present embodiment, part of a first color light emitted from the LEDs  112  strikes the first phosphor  13  of the first film  13  to generate a second color light. Part of the second color light strikes the second phosphor  141  of the second film  14  to generate a third color light. Part of the first color light emitted from the LEDs  112  strikes the second phosphor  141  of the second film  14  to generate a fourth color light. Finally, the combination of the unconverted first color light, the second color light, the third color light, and the fourth color light produces light of a desired color or colors. In one example, the unconverted first color light, the second color light, the third color light, and the fourth color light mix and produce mixed light of a single desired color. Different densities of phosphor can absorb different proportions of light emitted from the light source  11 , and thus emit light with different colors. Therefore, the density of the first and second phosphors  131 ,  141  can be varied in the first and second films  13 ,  14  to achieve light of any of numerous different desired colors. 
     It will be understood that in alternative embodiments, the illuminating apparatus  100  can include more than two films stacked one on the other. In addition, the surface  121  of the optical lens  123 , surfaces of the first film  13 , and surfaces of the second film  14  need not necessarily be flat. In alternative embodiments, any one or more of such surfaces can for example be arc-shaped or wavy cross section. 
     In a conventional illuminating apparatus, phosphor is packaged in an LED, and it is difficult to ensure that the phosphor is evenly distributed in the LED. In the present embodiment, there is no need to package the first or second phosphors  131 ,  141  in the LEDs  112 . Instead, the first and second phosphors  131 ,  141  can be substantially evenly distributed in the first and second films  13 ,  14 , respectively. Thus manufacturing of the illuminating apparatus  100  can be simplified and cost-effective. Furthermore, if it is desired to the make the illuminating apparatus  100  have different light emission characteristics (e.g. emission of different colored light), there is no need to change the LEDs  112 . Only selected of the first and second phosphors  131 ,  141  of the first and second films  13 ,  14  need be changed. Therefore the illuminating apparatus  100  has good versatility in manufacturing. 
     Referring to  FIG. 2 , an illuminating apparatus  200 , in accordance with a second exemplary embodiment, includes a light source  21 , a supporting member  22 , a first film  23 , and a second film  24 . The illuminating apparatus  200  is distinguished from the illuminating apparatus  100  in that two screws  222  are also provided, the supporting member  22  includes a flat optical lens  221 , and the first film  23  further defines a plurality of regions  235 . 
     In the present embodiment, the light source  21  includes a substrate  211  having two first holes  2111 , and a plurality of LEDs  212  arranged on an inner side of the substrate  211 . The first holes  2111  have screw threads, and can be through holes or blind holes. In the present embodiment, the first holes  2111  are through holes. The optical lens  221  has two threaded through holes  2211 . The optical lens  221  can be locked in position opposite to emitting surfaces of the LEDs  212  by threaded engagement of the two screws  222  in the first holes  2111  and the through holes  2211 . 
     The first film  23  is attached on an outer side of the optical lens  221 . The regions  235  are doped with different kinds of phosphors. The different kinds of phosphors can be individually doped into different regions  235 , respectively. Alternatively, the different kinds of phosphors can be intermixed with each other to produce desired combinations of phosphors, and then the various combinations of phosphors can be individually doped into different regions  235 , respectively. In the present embodiment, the regions  235  have the same size and shape, and are evenly distributed in the first film  23 . First and second phosphors  231 ,  232  are alternately doped in the regions  235 . That is, for example, the first phosphor  231  is doped into every odd-numbered region  235  in a sequence of the first regions  235 , and the second phosphor  232  is doped into every even-numbered region  235  in the sequence. In a further refinement of this example, the first regions  235  are arranged in the form of an m×n array, i.e., a matrix. In contrast, the second film  24  is doped in a similar manner as that of the second film  14  of the first embodiment. 
     The illuminating apparatus  200  has advantages similar to those of the illuminating apparatus  100 . There is no need to package the first and second phosphors  231 ,  232  in the light source  21 . Manufacturing of the illuminating apparatus  200  can be simplified and cost-effective. In addition, the illuminating apparatus  200  has good versatility in manufacturing. 
     It will be understood that in alternative embodiments, the positions of the first film  23  and the second film  24  can be exchanged. In other alternative embodiments, there can be more that two first holes  2111 , through holes  2211  and screws  222 . 
     Referring to  FIG. 3 , an illuminating apparatus  300 , in accordance with a third exemplary embodiment, includes a light source  31 , a supporting member  32 , a first film  33  and a second film  34 . The illuminating apparatus  300  has a configuration similar to that of the illuminating apparatus  200 . The illuminating apparatus  300  is distinguished from the illuminating apparatus  200  in that two latch portions  322  and two holding members  323  are also provided, the supporting member  32  includes a flat optical lens  321 , and the second film  34  further defines a plurality of second regions  345 . 
     In the present embodiment, a cross-section of each of the holding members  323  is rectangular. The holding members  323  are arranged on a periphery of an inner side of a substrate  311  of the light source  31 , and are configured for holding the optical lens  321  in position a predetermined distance away from LEDs  312  of the light source  31 . A cross-section of each of the latch portions  322  is generally U-shaped. The latch portions  322  are hitched onto peripheral portions of outer sides of the substrate  311  and the second film  34 , and thereby secure the optical lens  321  on the holding members  323 . 
     The second regions  345  of the second film  34  are doped with different kinds of phosphors. The different kinds of phosphors can be individually doped into different second regions  345 , respectively. Alternatively, the different kinds of phosphors can be intermixed with each other to produce desired combinations of phosphors, and then the various combinations of phosphors can be individually doped into different second regions  345 , respectively. In the present embodiment, the second regions  345  have the same size and shape, and are evenly distributed in the second film  34 . 
     First regions  335  of the first film  33  and the second regions  345  of the second film  34  have the same size and shape. The first regions  335  of the first film  33  are respectively directly opposite to the second regions  345  of the second film  34 . First and third phosphors  331 ,  332  are alternately doped in the first regions  335 . That is, for example, the first phosphor  331  is doped into every odd-numbered first region  335  in a sequence of the first regions  335 , and the third phosphor  332  is doped into every even-numbered first region  335  in the sequence. Second and fourth phosphors  341 ,  342  are alternately doped in the second regions  345 . That is, for example, the second phosphor  341  is doped into every odd-numbered second region  345  in a sequence of the second regions  345 , and the fourth phosphor  342  is doped into every even-numbered second region  345  in the sequence. The first phosphor  331 , the third phosphor  332 , the second phosphor  341 , and the fourth phosphor  342  are excited by the light emitted from the light source  31  and convert the wavelength of such light. Therefore, the illuminating apparatus  300  can emit light with different desired colors. 
     Referring to  FIG. 4 , in a variation of the third exemplary embodiment, the first regions  335  of the first film  33  can be staggered relative to the second regions  345  of the second film  34 . In the illustrated embodiment, each first region  335  is positioned to correspond to approximately half of each of two adjacent second regions  345 . 
     The illuminating apparatus  300  has advantages similar to those of the illuminating apparatus  100 . There is no need to package the first, second, third and fourth phosphors  331 ,  341 ,  332 ,  342  in the light source  31 . Manufacturing of the illuminating apparatus  300  can be simplified and cost-effective. In addition, the illuminating apparatus  300  has good versatility in manufacturing. 
     It will be understood that in alternative embodiments, the holding members  323  and the latch portions  322  may have other shapes, and there can be more than two holding members  323  and latch portions  322 . 
     It is to be further understood that even though numerous characteristics and advantages have been set forth in the foregoing description of embodiments, together with details of the structures and functions of the embodiments, the disclosure is illustrative only; and that changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.