Patent Publication Number: US-10317781-B2

Title: Lighting apparatus and laser diode module

Description:
FIELD OF THE INVENTION 
     The present invention relates to a lighting structure, and more particularly to a lighting apparatus for emitting a structural light. 
     BACKGROUND OF THE INVENTION 
     Taiwanese Utility Patent No. M490043 discloses a projection apparatus for projecting plural images. The projection apparatus comprises an outer frame, an optical source module and a diffractive optical element. The optical source module is installed within a lateral end of the outer frame. The diffractive optical element is disposed within the outer frame, and separated from the optical source module. The projection apparatus can project plural images. Consequently, the problem of projecting only a single virtual image by the conventional projection apparatus is overcome. 
     Although the conventional projection apparatus for projecting plural images is effective to overcome the problem of projecting the single monotonous image, there are still some drawbacks. For example, since the volume of this projection apparatus is large, the applications of the projection apparatus to modern wearable devices, portable communication devices, image capture devices and/or detecting devices are restricted. 
     SUMMARY OF THE INVENTION 
     One objective of present invention is to provide a lighting apparatus with small volume. Since an optical member is directly fixed on a substrate to cover plural lighting chips, the height and the volume of the overall lighting apparatus are reduced. Consequently, the lighting apparatus is suitably applicable to wearable devices. 
     Another objective of present invention is to provide a lighting apparatus with novel type of optical components. The lighting apparatus can be used as a laser diode module for structured lighting. A film-type or layer-type optical component is used for collimating plural laser beams and converting the laser beams into a structured light with a specified pattern. Consequently, the lighting apparatus is suitably employed to a portable image capture device or a portable detecting device. 
     A further objective of present invention is to provide a compact laser diode module with color option. The laser diode module comprises plural lighting and an optical member with a diffractive optical element. Consequently, plural dot laser beams are collimated and guided as a white light or a colorful structure light. 
     In accordance with an aspect of the present invention, there is a lighting apparatus to be provided. The lighting apparatus includes a substrate, plural lighting chips and an optical component. The substrate includes a circuit block or body (which could be slim or in multiple-layer printed circuit board). The plural lighting chips are fixed on the substrate. The circuit block on the substrate is related to operations of the plural lighting chips. The covering body is fixed on the substrate. The plural lighting chips are covered by the covering body. The covering body has a surface. The optical component is fixed on the surface of the covering body. After plural light beams emitted by the plural lighting chips pass through the optical component, a structural light pattern is produced. 
     In an embodiment, the plural light beams emitted by the plural lighting chips include plural laser beams. The plural laser beams have wavelengths in an ultraviolet band, a visible band, an infrared band, a near infrared band, a mid-infrared band, a thermal band or a combination thereof. 
     In an embodiment, the plural light beams have wavelengths of a red light, a green light and a blue light. 
     In an embodiment, the optical component is a single-layered film, a multi-layered film or a composite film that is attached on the surface of the covering body. 
     In an embodiment, the surface of the covering body includes an inner surface and/or an outer surface, wherein the inner surface of the covering body faces the plural lighting chips, and the outer surface of the covering body is exposed outside. 
     In an embodiment, the plural lighting chips are disposed on a mounting surface of the substrate. A distance between the optical component on the outer surface of the covering body and the mounting surface of the substrate is not larger than 3.0 mm. 
     In an embodiment, the optical member further includes a diffractive optical element, and the diffractive optical element is disposed on the outer surface of the covering body. The outer surface of the covering body has a light outputting surface for the plural light beams, and a numerical aperture (NA) of the light outputting surface is smaller than 0.65. 
     In an embodiment, the optical component includes a guiding lens and/or a diffractive optical element. 
     In an embodiment, the guiding lens is a wedge-bending light guider. 
     In an embodiment, a distance between every two adjacent ones of the plural lighting chips is smaller than 1.0 mm. 
     In an embodiment, the surface of the covering body is a flat surface or a curvy surface. 
     In an embodiment, the circuit block further includes a driving circuit, wherein the plural lighting chips are synchronously or asynchronously driven by the driving circuit, so that a coverage range and a profile of the structural light pattern are changeable. 
     In an embodiment, the circuit block comprises a driving circuit and one or plural photosensive components. 
     In an embodiment, the one or plural photosensive components sense light beams with different wavelengths. 
     In an embodiment, the plural lighting chips are arranged in a ring-shaped configuration, and a diameter of the ring-shaped configuration is not larger than 5.0 mm. 
     In accordance with another aspect of the present invention, there is provided a laser diode module. The laser diode module includes a substrate, plural lighting chips and an optical member. The plural lighting chips are fixed on the substrate. The optical member covers the plural lighting chip, and comprising a diffractive structure. After plural light beams emitted by the plural lighting chips pass through the diffractive structure, a structural light pattern is produced. 
     In an embodiment, the plural light beams emitted by the plural lighting chips include plural laser beams. The plural laser beams have wavelengths in an ultraviolet band, a visible band, an infrared band, a near infrared band, a mid-infrared band, a thermal band or a combination thereof. 
     In an embodiment, the plural light beams have wavelengths of a red light, a green light and a blue light. 
     In an embodiment, the optical member includes a covering body, and the diffractive structure is a single-layered film, a multi-layered film or a composite film that is attached on an inner surface and/or an outer surface of the covering body. The inner surface of the covering body faces the plural lighting chips. The outer surface of the covering body is exposed outside. 
     In an embodiment, the plural lighting chips are disposed on a mounting surface of the substrate. If the diffractive structure is attached on the outer surface of the covering body, a distance between a climax of the diffractive structure and the mounting surface of the substrate is not larger than 3.0 mm. If the diffractive structure is attached on the inner surface of the covering body, a distance between the outer surface of the covering body and the mounting surface of the substrate is not larger than 3.0 mm. 
     In an embodiment, the optical member further includes a guiding lens, and guiding lens is fixed on the inner surface or the outer surface of the covering body. Moreover, one of the guiding lens and the diffractive structure is disposed on the inner surface of the covering body, and the other of the guiding lens and the diffractive structure is disposed on the outer surface of the covering body. 
     In an embodiment, the optical member has a light outputting surface for the plural light beams, and a numerical aperture (N.A.) of the light outputting surface is smaller than 0.65. 
     In an embodiment, the optical member has a light outputting surface for the plural light beams, and a numerical aperture (N.A.) of the light outputting surface is smaller than 0.5. 
     In an embodiment, the optical axel of the plural lighting chips are in parallel with each other, or an included angle between every two adjacent ones of the plural optical axes is not larger than 5 degrees. 
     In an embodiment, the optical member further includes a wedge-bending light guider. Moreover, one of the diffractive structure and the wedge-bending light guider is disposed on an inner surface of the covering body, and the other of the diffractive structure and the wedge-bending light guider is disposed on the outer surface of the covering body. The inner surface of the covering body faces the plural lighting chips. The outer surface of the covering body is exposed outside. An inclination angle of the wedge-bending light guider is smaller than 15 degrees. 
     In an embodiment, a distance between every two adjacent ones of the lighting chips is smaller than 1.0 mm, or the plural lighting chips are arranged in a ring-shaped configuration with a diameter not larger than 5.0 mm. 
     In an embodiment, the substrate further includes a driving circuit for driving the plural lighting chips. The plural lighting chips are synchronously or asynchronously driven by the driving circuit, so that a coverage range and a profile of the structural light pattern are changeable or replaceable. 
     In an embodiment, the structural light pattern is composed of random dots, symmetric non-interlaced stripes, asymmetric non-interlaced stripes, symmetric interlaced stripes or asymmetric interlaced stripes. When the plural lighting chips are synchronously driven by the driving circuit, a density of the random dots is increased or a distribution range of the random dots is widened, a density of the symmetric non-interlaced stripes or a light stripe density or a distribution range of the asymmetric non-interlaced stripes is increased, and a density of the symmetric interlaced stripes or a light stripe density or a distribution range of the asymmetric interlaced stripes is increased. 
     In an embodiment, the structural light pattern is composed of random dots, symmetric non-interlaced stripes, asymmetric non-interlaced stripes, symmetric interlaced stripes or asymmetric interlaced stripes. When the plural lighting chips are asynchronously driven by the driving circuit, a viewing block corresponding to the structural light pattern is partially or completely scanned. 
     From the above descriptions, the present invention provides a lighting apparatus. An optical member with a diffractive optical element is directly fixed on the substrate with the lighting chips. When the lighting apparatus is used as a laser diode module, the height and volume of the overall module are reduced. Consequently, the lighting apparatus is suitably used in small-sized devices which are demanded emergently. 
     The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic top view illustrating a substrate and lighting chips of a lighting apparatus according to an embodiment of the present invention; 
         FIG. 2  is a schematic cross-sectional view of the lighting apparatus of  FIG. 1  and taken along the line AA′; 
         FIG. 3  is a schematic cross-sectional view illustrating the relationship between the substrate, the lighting chips and an optical member of a lighting apparatus according to a first embodiment of the present invention; 
         FIG. 4  is a schematic cross-sectional view illustrating the relationship between the substrate, the lighting chips and an optical member of a lighting apparatus according to a second embodiment of the present invention; 
         FIG. 5  is a schematic cross-sectional view illustrating the relationship between the substrate, the lighting chips and an optical member of a lighting apparatus according to a third embodiment of the present invention; 
         FIG. 6  is a schematic cross-sectional view illustrating the relationship between the substrate, the lighting chips, reflective mirrors and an optical member of a lighting apparatus according to a fourth embodiment of the present invention; and 
         FIG. 7  is a schematic perspective view illustrating the pattern and viewing angle of a structural light from the lighting apparatus of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The term “substrate” used herein indicates a printed circuit board (PCB), wherein one or more circuit blocks for implementing specified functions or plural conductive traces for communicating these circuit blocks are mounted thereon. Alternatively, the substrate is a combination of a printed circuit board and a flexible circuit board or a combination of a printed circuit board and a non-rigid circuit board. For example, the substrate is a heat-dissipation metal plate or a sapphire substrate. The term “circuit block” used herein comprises plural conductive traces, active or passive components (e.g., one or more photosensive components or one or more optical components) or integrated circuits. For example, the circuit block is driving circuit for driving chips. Moreover, other circuits, active or passive components (e.g., one or more photosensive components or one or more optical components) or other integrated circuits are mounted on the substrate. 
     The term “lighting chip” used herein indicates the chip for emitting a laser beam (e.g., a semiconductor laser chip). In particular, the lighting chip emits a laser beam with a specified wavelength. For example, the laser beam is an ultraviolet laser beam, a visible laser beam, an infrared laser beam, a near infrared laser beam or a mid-infrared (MIR) laser beam. The visible laser beam at least comprises a red light, a green light and a blue light. Alternatively, the lighting chip emits a laser-like beam with a thermal band or a mixed laser-like beam with the above specified wavelengths. The laser-like source means that the coherence is incomplete, and can be classified as a source of partial coherence. The wavelength band is not a single sharp band, but with broad band/multiple peaks. According to the desired arrangement, the type of the lighting chip includes an edge emitting laser (EEL) chip or a vertical-cavity surface-emitting laser (VCSEL) chip. 
     The term “optical member” used herein is a component for receiving the laser beam, converting the laser beam and outputting the converted laser beam. Moreover, the lighting chip fixed on the substrate is partially or completely covered by the optical member. When the lighting chip is covered by the optical member, the lighting chip and the optical member are separated from each other by a specified distance. The optical member comprises a covering body and an optical component fixed on the covering body. The optical member comprises a covering body and an optical component fixed on the covering body. The optical component is an optical structure that is directly formed on the covering body by a physical method or a chemical method; or the optical component is an object that is fixed on the covering body by an attaching means, an adhering means or any other appropriate fixing means. Moreover, the covering body, the optical component or the optical member is made of a light-transmissible material. Preferably but not exclusively, the covering body is made of polymethyl methacrylate (PMMA), polycarbonate (PC), K9, BK7, calcium fluoride compound (CaF2), calcium fluoride crystal, sapphire, silicon, quartz glass, crystal, glass or resin. The optical component is directly formed by using the material of the covering body, or the optical component is a coated film attached on the covering body. Moreover, the coated film is a single-layered film, a multi-layered film or a composite film. 
     Moreover, the shape of the optical member may be determined according to the arrangement of the lighting chips to be covered and the functions of inputting and outputting light beams. For example, the optical member may have a cylindrical shape, a polyhedral shape or any other appropriate shape. Moreover, the optical member is fixed on the substrate by an appropriate means. For example but not exclusively, the optical member is an inset element that is inserted into the corresponding insertion hole of the substrate, or the optical member is fixed on the substrate via an adhesive. 
       FIG. 1  is a schematic top view illustrating a substrate and lighting chips of a lighting apparatus according to an embodiment of the present invention.  FIG. 2  is a schematic cross-sectional view of the lighting apparatus of  FIG. 1  and taken along the line AA′. As shown in  FIGS. 1 and 2 , the substrate  10  of the lighting apparatus  1  comprises a circuit block  11  and four lighting chips  12 ,  14 ,  16  and  18 , which are fixed on the substrate  10 . The optical axes of the four lighting chips  12 ,  14 ,  16  and  18  are in parallel with each other. For example, as shown in  FIG. 2 , the optical axes  121 ,  141  and  181  are in parallel with each other and perpendicular to the substrate  10 . In particular, the included angle between every two of the optical axes  121 ,  141  and  181  is not larger than 5 degrees. It is noted that the optical axes of the lighting chips are not restricted to be perpendicular to the substrate. According to the design or use requirement, the optical axes of the lighting chips are inclined relative to the substrate. That is, a lighting surface of the lighting chip is inclined relative to the substrate at an inclination angle. Moreover, the four lighting chips  12 ,  14 ,  16  and  18  are edge emitting laser chips or vertical-cavity surface-emitting laser chips. Consequently, the optical axes defined by the lighting surfaces of the lighting chips  12 ,  14  and  18  may be guided by other optical elements such as reflective mirrors (not shown) so as to be the optical axes  121 ,  141  and  181  that are perpendicular to the substrate  10 . Similarly, the optical axis defined by the light output surface of the lighting chip  16  may be guided by other optical elements such as reflective mirrors (not shown) so as to be the optical axis that is perpendicular to the substrate  10 . For succinctness, the optical axis of the lighting chip  16  that is perpendicular to the substrate  10  is not shown. In an embodiment, the distance P between the lighting chips  12  and  16  is smaller than 1.0 mm. That is, the distance between every two adjacent lighting chips fixed on the substrate  10  is smaller than 1.0 mm. Alternatively, the plural lighting chips are arranged in a ring-shaped configuration O, and a diameter of the ring-shaped configuration O is not larger than 5.0 mm. Since the equivalent area of these lighting chips is very small, the volume is small. Moreover, the function of the circuit block  11  is related to the operations of the lighting chips  12 ,  14 ,  16  and  18 . For example, the circuit block  11  comprises a driving circuit for driving the lighting chips  12 ,  14 ,  16  and  18 . In particular, the driving circuit is used for driving the lighting chips  12 ,  14 ,  16  and  18  to emit dot laser beams. In addition to the circuit block  11 , one or more optical elements are fixed on the substrate  10 . For example, one or more photodiodes  17  or other sensing parts or sensing components are fixed on the substrate  10 . The photodiodes  17 , the sensing parts or the sensing components can sense the light beams with different wavelengths. In case that the photodiode  17  or the sensing component is small, the photodiode  17  or the sensing component can be fixed on the lighting chips  12 ,  14 ,  16  or  18 . 
       FIG. 3  is a schematic cross-sectional view illustrating the relationship between the substrate, the lighting chips and an optical member of a lighting apparatus according to a first embodiment of the present invention. Please refer to  FIGS. 1 and 3 . The optical member  20  is fixed on the substrate  10 . The optical member comprises a covering body  22  that covers the lighting chips  12 ,  14 ,  16  and  18 . The covering body  22  has an inner surface  221  and an outer surface  223 . The inner surface  221  faces the lighting chips  12 ,  14 ,  16  and  18 . The outer surface  223  is exposed outside. The inner surface  221  and the outer surface  223  are flat surfaces or curvy surfaces. The inner surface  221  of the covering body  22  is separated from the lighting chips  12 ,  14 ,  16  and  18  by a specified distance. The optical member  20  further comprises an optical component  24 . For example, the optical component  24  is a diffractive optical element (DOE) and used as a guiding lens. The optical component  24  is disposed on the outer surface  223  the covering body  22 . Preferably, the distance L between the climax of the optical component  24  and the surface of the substrate  10  that the lighting chips are mounted thereon is not larger than 3.0 mm. 
     As mentioned above, for reducing the height of the optical member  20 , the optical component  24  is a film-type object or a layer-type object formed on the covering body  22  or directly formed on the outer surface  223  of the covering body  22  by a physical method or a chemical method. After the plural light beams  122 ,  142  and  182  from the lighting chips  12 ,  14  and  18  and the light beam from the lighting chip  16  (not shown) pass through the optical component  24  of the optical member  20 , a structural light pattern  26  is produced. Depending on the diffractive structure of the optical component  24  (especially the diffractive structure for collimating the light beams), the form of the structural light pattern  26  is diversified. 
       FIG. 4  is a schematic cross-sectional view illustrating the relationship between the substrate, the lighting chips and an optical member of a lighting apparatus according to a second embodiment of the present invention. As shown in  FIG. 4 , the optical component  34  is disposed on the inner surface  321  of the covering body  32 . In this embodiment, the distance L between the outer surface  323  of the covering body  32  and the surface of the substrate  10  that the lighting chips are mounted thereon is not larger than 3.0 mm. As mentioned above, the optical member with the covering body is disposed over the lighting chips to cover the lighting chips. After the laser beams from the lighting chips are received by the optical member, the laser beams are collimated and converted into the structural light pattern by the optical member. Consequently, the structural light pattern is outputted from the optical member. Moreover, the covering body of the optical member has a light outputting surface. The numerical aperture (NA) of the light outputting surface of the optical member is smaller than 0.65, and more preferably smaller than 0.5. In other words, the light outputting surface of the optical member has an effective size of at least 0.1 mm so as to provide enough light outputting area to output the structural light pattern. 
       FIG. 5  is a schematic cross-sectional view illustrating the relationship between the substrate, the lighting chips and an optical member of a lighting apparatus according to a third embodiment of the present invention. As shown in  FIG. 5 , the optical member  40  further comprises a diffractive structure  44  and plural guiding lenses  48 . The diffractive structure  44  is formed on the outer surface  423  of the covering body  42 . The guiding lenses  48  are fixed on the inner surface  421  of the covering body  42 . The guiding lenses  48  are coated films, or the guiding lenses  48  are optical structures that are directly formed on the covering body  42 . The guiding lenses  48  are used for guiding the plural light beams  122 ,  142  and  182  from the lighting chips  12 ,  14  and  18  and the light beam from the lighting chip  16  (not shown). Moreover, in this embodiment, the photodiode  17  or the sensing component is not covered by the covering body  42 . It is noted that the guiding lenses  48  are not restricted to the typical light guiding elements as shown in  FIG. 5 . In some other embodiments, the guiding lenses  48  are wedge-bending light guiders. By the wedge-bending light guiders, the plural light beams  122 ,  142  and  182  from the lighting chips  12 ,  14  and  18  and the light beam from the lighting chip  16  (not shown) are translated or corrected. For example, in case that the guiding lenses  48  are wedge-bending light guiders with an inclination angle of 15 degrees, 5-degree deviation of the light beams  122 ,  142  and  182  from the lighting chips  12 ,  14  and  18  can be effectively corrected. 
       FIG. 6  is a schematic cross-sectional view illustrating the relationship between the substrate, the lighting chips, reflective mirrors and an optical member of a lighting apparatus according to a fourth embodiment of the present invention. As shown in  FIG. 6 , the lighting surfaces of the lighting chips  52  and  54  fixed on the substrate  10  is not perpendicular to the surface of the substrate  10  that the lighting chips  52  and  54  are fixed thereon. Moreover, two reflective mirrors  55  corresponding to the lighting chips  52  and  54  are also fixed on the substrate  10 . The lighting chips  52  and  54  and the two reflective mirrors  55  are covered by the covering body  62 . The optical component  64  is disposed on the outer surface of the covering body  62 . In this embodiment, the light beams from the lighting chips  52  and  54  are guided by the two reflective mirrors  55  so as to be formed as the light beams  522  and  542 . The light beams  522  and  542  are perpendicular to the surface of the substrate  10  that the lighting chips  52  and  54  are fixed thereon. 
       FIG. 7  is a schematic perspective view illustrating the pattern and viewing angle of a structural light from the lighting apparatus of the present invention. Please refer to  FIGS. 1, 3 and 7 . The altitude of the lighting apparatus  1  with respect to the floor is H. The structural light pattern  26  from the lighting apparatus  1  has a viewing block  66 . The distance between the viewing block  66  and the lighting apparatus  1  is D. The structural light pattern  26  is static or dynamic. Moreover, the structural light pattern  26  is regularly or irregularly distributed. In case that the structural light pattern  26  is dynamic, the pattern can be move, rotated, enlarged or shrunken, or the coverage range thereof is variable. In case that the driving methods of the driving circuit of the circuit block  11  are different, the structural light pattern  26  is adjustable. In an embodiment, when the driving current receives electric current, the lighting chips  12 ,  14 ,  16  and  18  are synchronously or asynchronously operated. Under this circumstance, the distribution range and the profile of the structural light pattern  26  are changeable. Alternatively, the viewing block  66  corresponding to the structural light pattern  26  is partially or completely scanned. The area of the structural light pattern  26  is smaller than, larger than or equal to the viewing block  66 . Moreover, by changing the driving method of the driving circuit, the way of scanning the structural light pattern  26  is changeable. For example, if the lighting chips  12 ,  14 ,  16  and  18  are sequentially turned on in an asynchronous order, the viewing block  66  corresponding to the structural light pattern  26  is partially or completely scanned. 
     In an embodiment, the structural light pattern  26  is composed of random dots. If the lighting chips  12 ,  14 ,  16  and  18  are synchronously driven by the driving circuit, the density of the random dots of the structural light pattern  26  is increased or the distribution range of the random dots is widened. In another embodiment, the structural light pattern  26  is composed of symmetric non-interlaced stripes or asymmetric non-interlaced stripes. If the lighting chips  12 ,  14 ,  16  and  18  are synchronously driven by the driving circuit, the light stripe density or the distribution range of the structural light pattern  26  is increased. In a further embodiment, the structural light pattern  26  is composed of symmetric interlaced stripes or asymmetric interlaced stripes. If the lighting chips  12 ,  14 ,  16  and  18  are synchronously driven by the driving circuit, the light stripe density or the distribution range of the structural light pattern  26  is increased. Moreover, if the lighting chips  12 ,  14 ,  16  and  18  are sequentially turned on in an asynchronous order, the viewing block  66  is partially or completely scanned by the structural light pattern  26 . 
     From the above descriptions, the lighting apparatus of the present invention has the following benefits. Firstly, since the optical member with the diffractive optical element is used for directly collimating the plural laser beams, the height and volume of the overall lighting apparatus are reduced. Secondly, since the lighting apparatus comprises plural lighting chips, the plural laser beams from the plural lighting chips can be mixed as a white light or a colorful structure light with various colors. Thirdly, since the optical member is directly fixed on the substrate with the lighting chips, the lighting apparatus of the present invention is suitably applied to a wearable device, a portable image capture device or a portable detecting device. 
     In addition, the lighting apparatus of the instant disclosure would be put into practice in laser diode module manner, whose width and height are reduced to meet the small-volume demand of an electronic device. 
     While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.