Patent Abstract:
According to an aspect of the present invention, lenses used for directing the light beams from lighting elements in a direct lighting vehicular lamp are constructed on an inner lens assembly that is separate from the lamp enclosure. Such a physical separation of the lens assembly and the lamp enclosure may permit complex profiles incorporating stylistic and aesthetic features to be chosen for the lamp enclosure, while maintaining ease of manufacturability.

Full Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention generally relates to vehicular lamp design, and specifically to a direct lighting vehicular lamp potentially permitting complex styling and ease of manufacturability.  
         [0003]     2. Related Art  
         [0004]     Lamps (“direct lighting lamps”) frequently use lighting elements which face a zone sought to be lighted, and thus directly illuminate the zone. For example, light-emitting diodes (LED) may be used in vehicular lamps such as brake and tail lamps to directly illuminate a zone of interest lying in front of (facing) the LEDs. The direct lighting lamps differ from the indirect lighting lamps in that the indirect lighting lamps use reflecting surfaces (e.g., aluminum coated cones) to direct the beam to the zone in front (and thus do not face the zone sought to be lighted).  
         [0005]     Direct lighting lamps generally contain directing elements (such as spherical/cylindrical convex lenses) to direct the light output (from the light sources such as LEDs) to obtain desired illumination intensities in desired zones, while also typically giving a more uniform appearance.  
         [0006]     In a prior approach, lens used for directing the light output in a direct lighting vehicular lamp are constructed on an inner surface of the lamp enclosure. Such an approach may, however, constrain the designer to using less complex shapes (profiles) for the lamp enclosure, so that manufacturing of the lamp enclosure is maintained simple/feasible. Consequently, such an approach may not facilitate provision of desired stylistic/aesthetic features in the lamp enclosure.  
         [0007]     Thus, what is required is direct lighting vehicular lamp that provides considerable freedom to the designer and user in choosing the stylistic aspects (such as size and profile of the lamp enclosure) of the overall design. It may be further desirable that such a feature be provided while ensuring that the processes involved in manufacturing the lamp enclosure and various components/sub-assemblies of the lamp are maintained simple.  
         [0008]     Accordingly, the present invention provides a design for a direct lighting vehicular lamp that permits incorporating complex styling for the lamp, and ease of manufacturability. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The present invention will be described with reference to the accompanying drawings, which are described below briefly.  
         [0010]      FIGS. 1A, 1B  and  1 C are diagrams showing a 3D (three-dimensional) sectional view, a 3D view and a sectional view respectively from different angles of an example embodiment of a direct lighting vehicular lamp that uses an LED array as the lighting elements, according to an aspect of the present invention.  
         [0011]      FIGS. 2A, 2B  and  2 C are diagrams showing sectional views from different angles of the example embodiment shown in  FIGS. 1A-1C .  FIG. 2D  is a diagram showing the top view of the example embodiment shown in  FIGS. 1A-1C .  
         [0012]      FIG. 3  is a diagram showing an exploded view of the example embodiment shown in FIGS.  1 A- 1 C/ 2 A- 2 D, with the various components/sub-assemblies being shown separately.  
         [0013]      FIG. 4  is a diagram showing a  3 D view of the inner lens assembly used in the example embodiment of FIGS.  1 A- 1 C/ 2 A- 2 D.  
         [0014]      FIG. 5  is a diagram illustrating the need for using directing elements in a direct lighting vehicular lamp.  
         [0015]     In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit (s) in the corresponding reference number. 
     
    
     DETAILED DESCRIPTION  
       [0000]     1. Overview  
         [0016]     A direct lighting vehicular lamp provided according to an aspect of the present invention contains a lens assembly and a lamp enclosure provided as physically separate components. The lens assembly may contain multiple lenses directing the light output from one or more lighting elements, and the lamp enclosure covers the inner components (lens assembly and LEDs).  
         [0017]     Since the lamp enclosure is provided as a physically separate component from the lens assembly, the lamp enclosure can be designed to meet any desired specification, for example, to meet aesthetic/stylistic requirements.  
         [0018]     According to another aspect of the present invention, the lenses constructed on the inner lens assembly are cylindrical lenses. This allows greater tolerances to be provided to the mounting positions of the lighting elements on a corresponding mounting sub-assembly such as a printed circuit board (PCB).  
         [0019]     Several aspects of the invention are described below with reference to examples for illustration. It should be understood that numerous specific details, relationships, and methods are set forth to provide a full understanding of the invention. One skilled in the relevant art, however, will readily recognize that the invention can be practiced without one or more of the specific details, or with other methods, etc. In other instances, well-known structures or operations are not shown in detail to avoid obscuring the invention.  
         [0000]     2. Vehicular Lamp  
         [0020]      FIGS. 1A, 1B  and  1 C are diagrams showing a 3D (three-dimensional) sectional view, a 3D view and a sectional view respectively from different angles of an example embodiment of a direct lighting vehicular lamp that uses an LED array as the lighting elements, according to an aspect of the present invention. Each diagram in  FIGS. 1A-1C  is shown containing lamp enclosure  110 , inner lens assembly  115 , printed circuit board (PCB) sub-assembly  130  and casing  125 . Each Figure contains additional components, as suited in the corresponding view. While the following sections are described with respect to a direct lighting vehicular lamp that uses multiple LEDs as lighting elements, other lighting elements can also be used. Each component is described in further detail below.  
         [0021]     Inner lens assembly  115  contains the lenses used for directing the light output from LEDs (example LEDs  120  and  121 , shown in  FIG. 1C ) mounted on PCB sub-assembly  130 , and may be constructed using any clear and transparent polymer or glass. In an embodiment, inner lens assembly  115  is constructed using poly-carbonate material, and contains cylindrical lenses constructed on a surface facing the LEDs (example LEDs  120  and  121 ) on PCB sub-assembly  130 . Inner lens assembly  115  is mounted on PCB sub-assembly using fasteners (fastener  135  is shown in  FIG. 1A ).  
         [0022]     PCB sub-assembly  130  may be constructed using any PCB material and has LEDs mounted on it in a desired arrangement to obtain a desired illumination. LEDs may be of any type such as axial lead LEDs, surface-mount package, etc. PCB sub-assembly  130  is mounted on casing  125  using fasteners (fastener  135  is shown in  FIG. 1A ).  
         [0023]     Casing  125  is a structure on which inner lens assembly  115 , PCB sub-assembly  130  and lamp enclosure  110  are fitted. In an embodiment, casing  125  is constructed using fiber reinforced glass and has a groove to accommodate lamp enclosure  110 .  
         [0024]     Lamp enclosure  110  encloses inner lens  115  and PCB-subassembly  130 , and may be designed to have a desired shape/profile. Lamp enclosure  110  may be constructed using any clear and transparent polymer or glass, and in an embodiment is constructed using polycarbonate material.  
         [0025]      FIGS. 2A, 2B  and  2 C are diagrams showing sectional views from different angles of vehicular lamp  100 , and  FIG. 2D  is a diagram showing the top view of vehicular lamp  100 . The various components/assemblies shown in each of  FIGS. 2A-2D  correspond to similarly numbered components/assemblies in the drawings of  FIGS. 1A-1C .  
         [0026]     Since, directing elements used to obtain a desired illumination are constructed on an assembly (inner lens assembly  115  in FIGS  1 A- 1 C and  2 A- 2 D) physically separate from the lamp enclosure  110 , the designer/user has a greater degree of freedom in choosing desired stylistic/aesthetic features for lamp enclosure  110 . This may be better appreciated from  FIG. 3  which is a diagram showing an exploded view of vehicular lamp  100 , with lamp enclosure  110 , PCB sub-assembly  130 , inner lens assembly  115  and casing  125  being shown separately.  
         [0027]     It is generally desirable to construct lenses on inner lens assembly  115  such that greater error tolerance is provided to the positions at which LEDs in PCB sub-assembly  130  need to be mounted. In the example embodiment (vehicular lamp  100 ) shown in  FIGS. 1A-1C  and  2 A- 2 D, this is achieved using cylindrical lenses. The description is continued with an illustration of the inner lens assembly  115  in an example embodiment.  
         [0000]     3. Inner Lens Assembly  
         [0028]      FIG. 4  is a diagram showing a  3 D view of inner lens assembly  115  illustrating the construction of directing lenses on an inner surface (i.e., facing the LED array) of the inner lens assembly. Lenses  116 ,  417 - 420  are cylindrical lenses constructed on an inner surface. As may be seen from  FIGS. 1A-1C  and  2 A- 2 D, each of lenses  116 / 417 - 420  serves to direct the light output from two or more corresponding LEDs. Since each lens is cylindrical, corresponding LEDs may be positioned on PCB sub-assembly  130  with greater tolerance along the direction corresponding to the axis of the lens.  
         [0029]     Mounting brackets  430 - 434  are used for fastening inner lens assembly  115  to casing  125  (of  FIGS. 1A-1C  and  2 A- 2 D). While the above description is provided with respect to cylindrical lenses, other kinds of lenses may be used (for example, spherical lens), for example, where tolerance for LED positions is not a requirement.  
         [0030]     The operation of the lamp may be better appreciated with a brief description of the functioning of the optics and the need for directing elements in an LED lamp. This is provided below.  
         [0000]     4. Directing Elements in an LED Lamp  
         [0031]      FIG. 5  is a diagram illustrating the operation and use of directing elements in an LED lamp in one embodiment. The diagram is shown containing LEDs  520  and  521 , printed circuit board (PCB) sub-assembly  530 , lamp enclosure  595  and directing lenses  540  and  550 . Each component is described below in greater detail.  
         [0032]     LEDs  520  and  521 are representative LEDs (and may correspond to LEDs  120 - 121  of  FIG. 1A ) comprising an LED array used for providing the light source in lamp  100  (of  FIGS. 1A-1C ,  2 A- 2 D). In  FIG. 5 , the light produced by LEDs  520  and  521  has been approximated as originating from a point source. LEDs  520  and  521  are mounted on PCB sub-assembly  530  (which corresponds to PCB sub-assembly  130  of FIGS.  1 A- 1 C/ 2 A- 2 D), and may be mounted on a suitable assembly/casing (not shown) as described in sections above.  
         [0033]     Directing lenses  540  and  550  are positioned in the path of the light produced by LEDs  521  and  520 , and may be spherical or cylindrical lenses. Further, directing lenses  520  and  521  may be separate elements or constructed on a single element (usually of polymer or glass, and corresponding to inner lens assembly  115  of FIGS.  1 A- 1 C/ 2 A- 2 D).  
         [0034]     Curves  565  and  560  represent the intensity distribution of the light output from LEDs  520  and  521  respectively as a function of the angle from the optical axis (path  571  for LED  520  and path  581 for LED  521 ). The light intensity is maximum along the optical axis and decreases as the angle from the optical axis increases. Thus, for example, the intensity of light output from LED  520  along path  572  will be lesser than a corresponding intensity along path  571 .  
         [0035]     The effect of directing lenses  540  and  550  is to direct the light outputs from LEDs  521  and  520  respectively, and produce light outputs ( 591  and  590 ) so as to meet required specifications/standards. Without the effect of directing lenses  540  and  550 , the light outputs from LEDs  521  and  520  may not provide a desired (for example, as required by automotive standards) illumination meeting a corresponding photometric specification.  
         [0036]     Thus, an aspect of the present invention provides directing lenses (similar to directing lenses  540  and  550 ) as a separate unit, permitting the lamp enclosure to be designed using more complex profiles and incorporating desired aesthetic features.  
         [0000]     5. Conclusion  
         [0037]     While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.

Technology Classification (CPC): 5