Patent Publication Number: US-9845933-B2

Title: Illumination apparatus

Description:
This application is a Continuation of co-pending application Ser. No. 13/293,427, filed on Nov. 10, 2011, and the content of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an illumination apparatus and in particular to an illumination apparatus with a cover comprising a protrusion. 
     2. Description of the Related Art 
     The light-emitting diodes (LEDs) of the solid-state lighting elements have the characteristics of the low power consumption, low heat generation, long operational life, shockproof, small volume, quick response and good opto-electrical property like light emission with a stable wavelength, so the LEDs have been widely used in household appliances, indicator light of instruments, and opto-electrical products, etc. As the opto-electrical technology develops, the solid-state lighting elements have great progress in the light efficiency, operation life and the brightness, and LEDs are expected to become the main stream of the lighting devices in the near future. 
     Recently, LEDs have been used for general illumination applications. In some applications, there is a need to have a LEDs lamp with an omni-directional light pattern. However, conventional LEDs lamps are not suitable for this need. 
     SUMMARY OF THE DISCLOSURE 
     The present disclosure provides an illumination apparatus. 
     The illumination apparatus comprising: a cover comprising a first portion and a second portion; and a light source disposed within the cover. An average thickness of the first portion is greater than that of the second portion. 
     In another embodiment of the present disclosure, an illumination apparatus is provided. The illumination apparatus comprises: a cover comprising a first portion and a second portion; and a light source disposed within the cover. A transmittance of the first portion is less than that of the second portion. 
     In another embodiment of the present disclosure, an illumination apparatus is provided. The illumination apparatus comprises: a cover comprising a chamber; and an inner cover disposed in the chamber and comprising an inner chamber; a light source disposed within the inner chamber. The cover and the inner cover comprise a plurality of diffuser particles, and a concentration of the diffuser particles within the cover and the inner cover is different. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide easy understanding of the application, and are incorporated herein and constitute a part of this specification. The drawings illustrate the embodiments of the application and, together with the description, serve to illustrate the principles of the application. 
         FIG. 1  shows a perspective view of an illumination apparatus in accordance with the first embodiment of the present disclosure. 
         FIG. 2A  is a cross-sectional view of a cover of the illumination apparatus in accordance with the first embodiment of the present disclosure. 
         FIG. 2B  is a cross-sectional view of the cover of the illumination apparatus in accordance with the first embodiment of the present disclosure, showing a connecting means. 
         FIG. 3  is a coordinate system to describe the spatial distribution of illumination emitted by the illumination apparatus. 
         FIGS. 4A to 4F  shows covers with various shapes. 
         FIG. 5  is a cross-sectional view of the cover of the illumination apparatus in accordance with the second embodiment of the present disclosure. 
         FIG. 6  is a schematic cross-sectional view of the illumination apparatus in accordance with the first embodiment of the present disclosure. 
         FIG. 7  is a circuit diagram of the illumination apparatus in accordance with the first embodiment of the present disclosure. 
         FIG. 8A  is a cross-sectional view of the cover of the illumination apparatus in accordance with the third embodiment of the present disclosure. 
         FIG. 8B  is a cross-sectional view of the cover of the illumination apparatus in accordance with the fourth embodiment of the present disclosure. 
         FIG. 8C  is a cross-sectional view of the cover of the illumination apparatus in accordance with the fifth embodiment of the present disclosure. 
         FIG. 8D  is a cross-sectional view of the cover of the illumination apparatus in accordance with the sixth embodiment of the present disclosure. 
         FIG. 9A  is a cross-sectional view of the cover of the illumination apparatus in accordance with the seventh embodiment of the present disclosure. 
         FIG. 9B  is a cross-sectional view of the cover of the illumination apparatus in accordance with the seventh embodiment, showing different roughness density. 
         FIG. 10A  is a cross-sectional view of the cover of the illumination apparatus in accordance with the eighth embodiment of the present disclosure. 
         FIG. 10B  is a cross-sectional view of the cover of the illumination apparatus in accordance with the ninth embodiment of the present disclosure. 
         FIG. 10C  is a cross-sectional view of the cover of the illumination apparatus in accordance with the tenth embodiment of the present disclosure. 
         FIG. 10D  is a cross-sectional view of the cover of the illumination apparatus in accordance with the eleventh embodiment of the present disclosure. 
         FIG. 11  is a cross-sectional view of the inner cover. 
         FIGS. 12A to 12E  show simulated luminous intensity distributions at different distances (D). 
         FIGS. 13A to 13C  show different shapes of the inner cover. 
         FIGS. 14A to 14C  are simulated luminous intensity distributions. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     To better and concisely explain the disclosure, the same name or the same reference number given or appeared in different paragraphs or figures along the specification should has the same or equivalent meanings while it is once defined anywhere of the disclosure. 
     The following shows the description of the embodiments of the present disclosure in accordance with the drawings. 
       FIGS. 1 and 2A  disclose an illumination apparatus  100  according to the first embodiment of the present disclosure. The illumination apparatus  100  is a lamp bulb. The illumination apparatus  100  comprises a cover  11 ; a light source  14 ; a circuit unit  30  electrically connecting with the light source  14  for controlling the light source  14 ; and a heat sink  20  disposed between the cover  11  and the circuit unit  30  for conducting heat generated by the light source  14  away from the illumination apparatus  100 . 
     Referring to  FIG. 2A , the cover  11  comprises a first portion  111  and a second portion  112 , and defines a chamber  113  therein. The light source  14  is disposed within the chamber  113 . The first portion  111  is arranged in the center of the cover  11 , and the second portion  112  surrounds the first portion  111  and symmetrically extends from the first portion  111  in the opposite direction. In one embodiment, the first portion  111  and the second portion  112  comprise the same material. In this embodiment, the first portion  111  of the cover  11  comprises a protrusion  13  extending therefrom and toward the light source  14  such that the first portion  111  has an average thickness greater than that of the second portion  112 . In one embodiment, the average thickness of the first portion  111  is at least two times greater than that of the second portion  112 . The protrusion  13  of the first portion  111  has a curved surface  134  facing the light source  14  for defining an inner surface and has an area in a plane view larger than that of the light source  14 . In this embodiment, the protrusion  13  has a semi-circular shape in cross-section such that the first portion  111  has a non-uniform thickness where a central portion  131  of the first portion  111  is thicker than a peripheral portion  132  of the first portion  111 . In contrary, the second portion  112  has a substantially uniform thickness. Since the average thickness of the first portion  111  is greater than that of the second portion  112 , the transmittance of the first portion  111  is less than that of the second portion  112 , which results in some light emitted from the light source  14  are reflected by the first portion  111 . By virtue of the thickness difference between the first and second portions  111 ,  112 , an omni-directional light pattern can be achieved. In one embodiment, less than 80% of the light emitted by the light source  14  is transmitted through the first portion  111 , and more than 80% of the light emitted by the light source  14  is transmitted through the second portion  112 . In addition, the first and second portions  111 ,  112  comprise a plurality of diffuser particles dispersed therein, such as TiO 2 , SiO 2 , or air. The more the diffuser particles are, the less the transmittance of the first and second portions  111 ,  112  is. 
     The illumination apparatus  100  further comprises a holder  15  supporting the light source  14  and connected with the cover  11 . The holder  15  is disposed between the cover  11  and the heat sink  20 , and the light source  14  is directly disposed on/above the holder  15 . In another embodiment, the light source  14  is disposed within the center of the chamber  113  and is supported by the holder  15  through a post (not shown). The holder  15  and the post have heat dissipation properties such that heat generated by the light source  14  can be conducted to the heat sink  20  therethrough. 
     In this embodiment, the protrusion  13  and the cover  11  (the first portion  111  and the second portion  112 ) comprise the same material and are formed by molding such as injection molding, thereby monolithically integrating with each other to form a single-piece object. The “monolithically integrating” means that there is no boundary existing between the protrusion  13  and the cover  11 . It is noted that, as shown in  FIG. 2B , the second portion  112  comprises an upper part  1121  extending from the first portion  111  and a lower part  1122  downwardly extending from the upper part  1121 . The holder  15  is connected with the lower part  1122 . In one embodiment, the upper part  1121  and the lower part  1122  of the second portion  112  are formed as two separate pieces and combined using a connecting means  19  which is arranged close to the holder  15 , as shown in  FIG. 2B . Alternatively, the connecting means  19  can be arranged in the central position of the cover  11  (not shown). The connecting means  19  comprises screw, fasteners, buckles, or clips. In another embodiment, the upper part  1121  and the lower part  1122  are formed as a one-piece member. The cover  11  comprises glass or polymer, such as polyurethane (PU), polycarbonate (PC), polymethylmethacrylate (PMMA), or polyethylene (PE). The protrusion  13  can be solid or hollow. 
     Moreover, referring to  FIG. 2A , the protrusion  13  further comprises a reflective coating  133  formed on the inner surface. Therefore, when the light emitted by the light source  14  passes toward different directions as indicated by the arrow L, some of the light passes through the second portion  112  and exits the cover  11 , and some of the light emitting toward the protrusion  13  is substantially reflected by the reflective coating  133  and is directed downwardly to exit the cover  11  such that some light exist under the plane (P). The light source  14  has an optical axis (Ax, θ=0° as shown in  FIG. 3 ). The plane (P, θ=90° as shown in  FIG. 3 ) is a horizontal plane orthogonal to the optical axis and is coplanar with the holder  15  on which the light source  14  is disposed. Specifically, as shown in  FIG. 3 , a coordinate system is used to describe the spatial distribution of the illumination emitted by the light source  14  or the illumination apparatus  100 . A direction of the illumination is described by a coordinate θ in a range [0°, 180°]. By virtue of the protrusion  13  comprising the reflective coating  133  formed thereon or by virtue of the thickness difference between the first and second portions  111 ,  112 , the direction of the illumination emitted by the illumination apparatus  100  is in a range from 135° to −135° (φ 1 =270°) for achieving an omni-directional light pattern. It is noted that “omni-directional light pattern” means more than 5% of the light emitted by the light source  14  is existing in the range from −135° to 135° (φ 2 =90°). The “substantially reflected” means more than 90% of the light emitted by the light source  14  is reflected by the reflective coating  133  and less than 10% of the light emitted by the light source  14  is transmitted through the first portion  111 . In one embodiment, the reflective coating  133  can be formed on an outer surface opposite to the inner surface. The reflective coating  133  comprises paint with silver or aluminum. Alternatively, the reflective coating  133  can be a reflective layer (not shown) including a plurality of sub-layers formed as a Distributed Bragg Reflector (DBR). In another embodiment, the protrusion  13  comprises a rough surface, such as a nanostructure for scattering the light. 
       FIGS. 4A to 4F  disclose the cover with various shapes. Referring to  FIG. 4A , the protrusion  23  has a rectangular shape in cross-section and comprises the reflective coating  233  formed thereon. Referring to  FIG. 4B , the protrusion  33  comprises a first section  331  having a rectangular shape in cross-section, and a second section  332  extending from the first section  331  toward the light source and having a truncated shape in cross-section. In addition, the reflective coating  333  is formed on the first and second sections  331 ,  332  of the protrusion  33 . Referring to  FIG. 4C , the protrusion  43  comprises two inclined sidewalls  431  and has a trapezoidal shape in cross-section. The protrusion  43  further comprises the reflective coating  433  formed thereon. Referring to  FIG. 4D , the protrusion  53  comprises a first part  531  having a rectangular shape in cross-section, and a second part  532  extending from the first part  531  toward the light source and having a circular shape in cross-section. Likewise, the protrusion  53  further comprises the reflective coating  533  formed thereon. Referring to  FIG. 4E , the protrusion  63  comprises a tip  631  corresponding to the center of the first portion  111 , and two curved surface  632  divergently extending from the tip  631 . The protrusion  63  further comprises the reflective coating  633  formed thereon. Referring to  FIG. 4F , the protrusion  73  has a similar structure to that in  FIG. 4E , except that the protrusion  73  has a flat surface  731  corresponding to the center of the first portion  111 . The protrusion  73  further comprises the reflective coating  733  formed thereon. 
       FIG. 5  discloses a cover of an illumination apparatus  200  according to the second embodiment of the present disclosure. The second embodiment of the illumination apparatus  200  has the similar structure with the first embodiment of the illumination apparatus  100 . In this embodiment, the second portion  812  of the cover  81  comprises a rough surface  8121 , such as a nanostructure for scattering the light. It is noted that the rough surface  8121  can be provided in portions of the second portion  812 . 
       FIG. 6  discloses a perspective view of the illumination apparatus  100  as shown in  FIG. 1 . The light source  14  is electrically connected with a board  16 , such as PCB board, which is disposed on the holder  15 .  FIG. 7  shows a circuit diagram of the circuit unit  30 . The circuit unit  30  comprises a bridge rectifier (not shown) electrically connected with a power source which provides an alternating current signal for receiving and regulating the alternating current signal into a direct current signal. In this embodiment, the light source  14  comprises a plurality of light-emitting diodes connected in series with each other. Alternatively, the light-emitting diodes can be connected in parallel or series-parallel with each other. The light source  14  can comprise the light-emitting diodes with the same wavelength. In one embodiment, the light source  14  comprises the light-emitting diodes with different wavelengths such as red, green and blue light-emitting diodes for color mixing, or a wavelength converter formed on the light-emitting diodes for generating a converted light having a wavelength different from the wavelength of the light emitting from the light source  14 . In one embodiment, the light source  14  can be a point light source, a planar light source, or a linear light source which comprises a plurality of light-emitting diodes arrange in a line. 
       FIG. 8A  discloses a cover of an illumination apparatus  300  according to the third embodiment of the present disclosure. The third embodiment of the illumination apparatus  300  has the similar structure with the first embodiment of the illumination apparatus  100 . The illumination apparatus  300  further comprises an inner cover  18  which is disposed in the chamber  113  and which is formed above the light source  14 . The inner cover  18  defines an inner chamber  183  therein and the light source  14  is disposed within the inner chamber  183 . In this embodiment, the inner cover  18  comprises two slanted sidewalls  181 , and a concave portion  182  extending between the sidewalls  181  and monolithically integrating with the slanted sidewalls  181 . The concave portion  182  has a triangular shape in cross-section. In this embodiment, more than 80% of the light emitted by the light source  14  is transmitted through the inner cover  18  toward the protrusion  111  of the cover  11  and is reflected by the protrusion  111 , thereby achieving the omni-directional light pattern. In addition, the first portion  111  has an area larger than that of the inner cover  18  in a plan view. The inner cover  18  is hollow and spaced apart from the light source  14 . The inner cover  18  comprises polymethylmethacrylate (PMMA), polycarbonate (PC), polyurethane (PU), or polyethylene (PE). 
       FIG. 8B  discloses a cover of an illumination apparatus  400  according to the fourth embodiment of the present disclosure. The fourth embodiment of the illumination apparatus  400  has the similar structure with the third embodiment of the illumination apparatus  300 . The inner cover  28  comprises a convex portion  282 , a plat surface  283  opposite to the convex portion  282 , and two slanted sidewalls  281  extending between the convex portion  282  and the flat surface  283 . The inner cover  28  is solid and there is an air gap  29  formed between the inner cover  28  and the light source  14 . In one embodiment, a wavelength converter (not shown) is formed on the flat surface  283 . 
       FIG. 8C  discloses a cover of an illumination apparatus  500  according to the fifth embodiment of the present disclosure. The fifth embodiment of the illumination apparatus  500  has the similar structure with the third embodiment of the illumination apparatus  300 . The inner cover  38  is disposed in the chamber  113  and above the light source  14 . The inner cover  38  defines an inner chamber  313  therein and the light source  14  is disposed within the inner chamber  313 . The cover  11  and the inner cover  38  comprise a plurality of diffuser particles (not shown) therein. The more the diffuser particles are, the less the transmittance is. Accordingly, the concentrations of the diffuser particles within the cover  11  and the inner cover  38  are adjustable to be different for achieving the omni-directional light pattern. The diffuser particles comprise TiO 2 , SiO 2 , or air. In this embodiment, the inner cover  38  further comprises a wavelength converter  381  formed on an outer surface thereof facing the protrusion  13  for generating a converted light having a wavelength different from the wavelength of the light emitting from the light source  14 . 
       FIG. 8D  discloses a cover of an illumination apparatus  600  according to the sixth embodiment of the present disclosure. The sixth embodiment of the illumination apparatus  600  has the similar structure with the third embodiment of the illumination apparatus  300 . The inner cover  48  comprises a first portion  481  having a sphere-like shape in cross-section and a second portion  482 . The inner cover  48  is hollow and defines an inner chamber  483  therein. The light source  14  is disposed within the inner chamber  483 . The second portion  482  is made of Ag or Al for reflecting the light emitted from the light source  14 . Alternatively, the second portion  482  comprises a reflective coating such as Ag or Al formed thereon. 
       FIG. 9A  discloses a cover of an illumination apparatus  700  according to the seventh embodiment of the present disclosure. The cover  41  comprises a rough structure formed on the inner surface  411 , and a smooth outer surface  412  opposite to the inner surface  411 . The cover  41  comprises plastic such as polymethylmethacrylate (PMMA), polycarbonate (PC), polyurethane (PU), polyethylene (PE), or glass. In this embodiment, the rough structure is formed by sand blasting, injection molding, polishing, or wet etching using an etchant such as acetone, ethyl acetate, or monomethyl ether acetate. In this embodiment, the rough structure has a uniform roughness density on the entire inner surface  411 . Alternatively, as shown in  FIG. 9B , the roughness density is different on the inner surface  411 , that is, the rough structure comprising a gradient in the roughness density from a central part  4111  to a peripheral part  4112  of the cover  41 . Due to the difference of the roughness density, the light emitted from the light source  14  is scattered more at the central part  4111  than that at the peripheral part  4112 . The roughness density is defined by a haze (H) value. The definition of haze is a ratio of scattering light (S) to the total light (scattering light (S)+transmitted light (T)). The haze value of the central part  4111  ranges from 0.5 to 0.9. The haze value of the peripheral part  4112  ranges from 0.3 to 0.6. 
       FIG. 10A  discloses a cover of an illumination apparatus  800  according to the eighth embodiment of the present disclosure. The eighth embodiment of the illumination apparatus  800  has the similar structure with the sixth embodiment of the illumination apparatus  600 . The inner cover  58  comprises a first light-guiding portion  581 , and a second light-guiding portion  582 . The first light-guiding portion  581  has a barrel-like shape in cross-section for efficiently guiding the light emitting from the light source  14  toward the second light-guiding portion  582 . The inner cover  58  further comprises a wavelength converter  583  formed on the second light-guiding portion  582  for generating a converted light having a wavelength different from the wavelength of the light emitting from the light source  14 . The second light-guiding portion  582  has a trapezoidal shape in cross-section for reflecting the light from the first light-guiding portion  581  toward the wavelength converter  583 . When the light emitted from the light source  14  through the first and second light-guiding portions  581 ,  582  toward the wavelength converter  583 , the light is converted and scattered by particles dispersed in the wavelength converter  583  such that the light is upwardly and downwardly transmitted through the cover  11  so as to achieve the omni-directional light pattern. In this embodiment, the first light-guiding portion  581  and the second light-guiding portion  582  comprise the same material, such as PMMA, PC, silicon, or glass. 
       FIG. 10B  discloses a cover of an illumination apparatus  900  according to the ninth embodiment of the present disclosure. The ninth embodiment of the illumination apparatus  900  has the similar structure with the eighth embodiment of the illumination apparatus  800 . The inner cover  68  further comprises a third light-guiding portion  684 _formed on the wavelength converter  683  such that the wavelength converter  683  is sandwiched between the second light-guiding portion  682  and the third light-guiding portion  684 . The third light-guiding portion  684  comprises two curved surfaces for reflecting the light toward a lateral direction. The first, second, and third light-guiding portions  681 ,  682 , and  684  can be solid or hollow. 
       FIG. 10C  discloses a cover of an illumination apparatus  1000  according to the tenth embodiment of the present disclosure. The tenth embodiment of the illumination apparatus  1000  has the similar structure with the ninth embodiment of the illumination apparatus  900  and comprises the first, second, and third light-guiding portions  781 ,  782 ,  784 . The first light-guiding portion  781  has a trapezoidal-like shape in cross-section for guiding the light toward the second light-guiding portion  782 . Each of the second and third light-guiding portions  782 ,  784  has a semi-circular shape in cross-section. The wavelength converter  783  is sandwiched between the second light-guiding portion  782  and the third light-guiding portion  784 . Due to the shape of the second and third light-guiding portions  782 ,  784 , a total reflection occurred at the interface between the light-guiding portions  782 ,  784  and air can be reduced. Likewise, when the light emitted from the light source  14  through the first and second light-guiding portions  781 ,  782  toward the wavelength converter  783 , the light is converted and scattered by particles dispersed in the wavelength converter  883  such that the light is upwardly and downwardly transmitted through the cover  71  so as to achieve the omni-directional light pattern. 
       FIG. 10D  discloses a cover of an illumination apparatus  1100  according to the eleventh embodiment of the present disclosure. The heat sink  20  extends into the chamber  113  of the cover  81 , and the light source  14  is disposed in the center of the chamber  113 . The inner cover  88  is formed above the light source  14  and comprises a light-guiding portion  881  and a wavelength converter  883  formed on the light-guiding portion  881 . Because of the position of the light source  14  (in the center of the chamber  113 ), when the light emitted from the light source  14  toward the wavelength converter  883 , the light is scattered by particles dispersed in the wavelength converter  883  such that light is upwardly and downwardly transmitted through the cover  81  so as to achieve the omni-directional light pattern. 
     Referring to  FIG. 11 , the inner cover  98  has a trapezoidal shape including a top surface having a first length (L 1 ), a bottom surface having a second length (L 2 ), and a height (H). The ratio of the first length (L 1 ) to the second length (L 2 ) is greater than 2 and the ratio of the height (H) to the second length (L 2 ) ranges from 1 to 1.5 for achieving the omni-directional light pattern. The height (H) is in a range of 3-9 mm. The bottom surface is inclined with respect to the height at an angle (α) ranging from 106° to 132.5°.  FIGS. 12A to 12E  show simulated luminous intensity distributions at different distances (D) from the light source  14  to the holder  15 , as shown in  FIG. 11 . The distances (D) shown in  FIGS. 11A to 11E  are 0 cm, 5 cm, 10 cm, 15 cm, and 20 cm, respectively. When the distance (D) is larger, the light intensity in the direction in a range from 0° to 90° is greater. 
       FIGS. 13A to 13C  show different shapes of the inner cover.  FIGS. 14A to 14C  show simulated luminous intensity distributions when the inner cover has different shapes as shown in  FIGS. 13A to 13C , respectively. When the inner cover  208  as shown in  FIG. 13B  comprises a cavity having two curved or inclined surfaces  2081 , the light intensity in the direction in a range from 110° to 130° is greater than the inner cover  108  shown in  FIG. 13A . Moreover, when the inner cover  308  further comprises a light-guiding portion  3081 , the light intensity in all directions is greater than the inner cover  108  shown in  FIG. 13A , for achieving the omni-directional light pattern. 
     It will be apparent to those having ordinary skill in the art that various modifications and variations can be made to the devices in accordance with the present disclosure without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the present disclosure covers modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.