Abstract:
A headlight of the type worn by medical and dental professionals includes a housing having an opening therein. A light source is positioned in the housing to output light through the opening. A singlet lens is mounted in the housing proximate the opening, and a doublet lens is disposed between the light source and the singlet lens.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/263,310 filed on Dec. 4, 2015, the disclosure of which is expressly incorporated by reference herein in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The invention relates generally to lighting devices and, more particularly, to portable lighting devices, such as surgical headlights. 
       BACKGROUND 
       [0003]    Portable lighting devices, such as lighting devices that are to be worn, are well known in the art. In many cases, a user may place a light on their head proximate their face. The light is then directed toward objects in the immediate vicinity of the user. As an example, these types of headlights may be used in surgical procedures. Medical and dental professionals often use surgical headlights to provide additional illumination of a surgical site on a patient. Surgical headlights may be attached to glasses or loupes to be worn by the clinician. 
         [0004]    Existing headlights can be deficient in one or more aspects. For one, they may exhibit poor light uniformity and/or unacceptable color separation at the edge of the light beam. In addition, surgical headlights may be too heavy or awkward and are therefore uncomfortable. As such, clinicians consider size, weight, and ease of adjustment when selecting a headlight for use in surgical procedures. 
         [0005]    To address some of these problems, U.S. Pat. No. 8,047,684 seeks to provide a more uniform light beam by positioning a singlet lens between a light-emitting diode (LED) and a doublet lens. This arrangement however has a drawback and does not address many of the clinicians&#39; selection criteria. For example, the positioning of the doublet lens at the distal opening of the housing results in the doublet lens having a relatively large diameter, and thus the doublet lens is relatively heavy. During lengthy surgical procedures, the clinician may experience head and neck discomfort and/or pain because of the relatively heavy doublet lens. 
         [0006]    Therefore, a need exists for a headlight which provides a more uniform light beam, and which is both lightweight and comfortable. 
       SUMMARY 
       [0007]    In one embodiment, a headlight of the type worn by medical and dental professionals includes a housing having an opening therein. A light source is positioned in the housing to output light through the opening. A singlet lens is mounted in the housing proximate the opening, and a doublet lens is disposed between the light source and the singlet lens. The light source may be a light emitting diode. 
         [0008]    The doublet lens may be achromatic. In addition or alternatively, the double lens may include first and second simple lenses. In one embodiment, a diameter of the doublet lens may be smaller than a diameter of the opening. 
         [0009]    In one embodiment, the singlet lens may have a diameter of between about 10 mm and about 14 mm. For example, the singlet lens may have a diameter of about 10 mm. In addition or alternatively, the singlet lens may have a thickness of between about 1 mm and about 3 mm. For example, the singlet lens may have a thickness of about 2 mm. 
         [0010]    In one embodiment, the doublet lens may have a diameter of between about 3 mm and about 7 mm. For example, the doublet lens may have a diameter of about 5 mm. In addition or alternatively, the doublet lens may have a thickness of between about 2 mm and about 4 mm. For example, the doublet lens may have a thickness of about 3 mm. 
         [0011]    In one embodiment, the opening may have a diameter of between about 9 mm and about 14 mm. 
         [0012]    In one embodiment, the doublet lens may be positioned proximate the light source. In addition or alternatively, the doublet lens may be positioned distally from the opening. 
         [0013]    In one embodiment, the housing may be configured for attachment to at least one of glasses or loupes. In addition or alternatively, the light source, singlet lens, and doublet lens may be configured such that light projected from the light source through the doublet lens and singlet lens provides uniform surface illumination. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the detailed description given below, serve to explain the invention. 
           [0015]      FIG. 1  is a perspective view of a headlight assembly in accordance with one embodiment of the present invention; and 
           [0016]      FIG. 2  is a cross-sectional view of the housing shown in  FIG. 1 , taken along line  2 - 2 . 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    With reference to  FIGS. 1 and 2 , in one embodiment, a headlight assembly  10  may include a housing  12 , a yoke  14 , and a through-the-lens (TTL) clip  16 . The TTL clip  16  may be configured for attachment to a user&#39;s glasses or loupes (not shown). For example, the TTL clip  16  may be positioned around a portion of a pair of glasses, and the thumb screw  18  may be tightened to secure the assembly  10  to the glasses. As is described below with reference to  FIG. 2 , multiple lenses  20 ,  22  and a light source  24  are arranged within the housing  12 . When energized, light from the light source  24  is projected through each lens  20 ,  22  and out of the housing  12 . Advantageously, the light beam passes through the lenses  20  and  22  to provide uniform surface illumination while the arrangement of the lenses  20 ,  22  in the housing  12  reduces weight, increasing user comfort. 
         [0018]    To these and other ends, with continued reference to  FIGS. 1 and 2 , the housing  12 , which may be constructed of aluminum, may be pivotally attached to the yoke  14 . In the embodiment shown, the housing  12  is attached to a second housing  34 , and the second housing  34  is pivotally attached to the yoke  14 , such as by a pin  26 . The yoke  14  may, in turn, be pivotally attached to the TTL clip  16 , such as by a screw  28 , lock washer  30 , and hex nut  32 . 
         [0019]    With reference to  FIG. 2 , in one embodiment, the housing  12  may be threadably attached to the second housing  34  ( FIG. 2 ), which may also be constructed of aluminum. As shown, the second housing  34  may include a fastening portion  60  including an eyelet  62  for receiving the pin  26 . The fastening portion  60  may further include first and second tabs  64 ,  66 , which may engage with corresponding features of the yoke  14  in order to provide first and second positive stops to pivotal movement of the second housing  34  relative to the yoke  14 , thereby limiting the pivoting range of the second housing  34  (and consequently the housing  12 ) relative to the yoke  14 . The second housing  34  may be proximate the light source  24  and so operate as a heat sink to dissipate heat therefrom. 
         [0020]    The housing  12  may have a generally elongated tubular body portion  38  that extends from a base portion  40 . The body portion  38  may have a generally circular cylindrical configuration that defines an opening  42  proximate one end  44  of the housing  12 . The body portion  38  may join or be formed integrally with the base portion  40 . The base portion  40  may be threadably attached to the second housing  34 . The light source  24  is positioned within the envelope formed by the housing  12  and the second housing  34  to oppose the opening  42  proximate the other end  46  of the housing  12 . 
         [0021]    As shown, in one embodiment, the body portion  38  may include tabs  48 ,  50  that extend radially inward on the interior surface of the housing  12 . The tabs  48 ,  50  may be configured to receive lenses  20 ,  22 , respectively, in fixed position relative to one another. For example, the lenses  20 ,  22  may be pressed against the tabs  48 ,  50 , and may optionally be adhered thereto. In addition, or alternatively, the body portion  38  may include a threaded retaining ring or insert  52  for receiving the lens  20  in a fixed position, such as, for example, by sandwiching the lens  20  in position against tab  48 . The insert  52  is secured to the housing  12  to hold the lens  20  in position. 
         [0022]    As shown, the light source  24  may be positioned at one end  46  of the housing  12  with the lens  20  between the lens  22  and the light source  24 . In the exemplary embodiment, the lens  20  may be a doublet lens and the lens  22  may be a singlet lens. In the exemplary embodiment, the light source  24  is a light emitting diode (LED). When energized, light from the LED  24  is projected through each lens  20 ,  22  and out of the opening  42  of the housing  12 . The LED  24  may include an integral lens  54 , which may be spherical and be attached to a circuit board  36 . The LED  24  may be electrically connected to a battery pack or other remote power source via a power connector (not shown). By way of example, a 0.7 mm DC power connector (not shown) may be electrically coupled to the circuit board  36 . In addition, or alternatively, a battery pack and power cable sold under the trademark Orascoptic may be used. As shown, first and second passageways  56 ,  58  may extend through the second housing  34  and may facilitate coupling of a power cable (not shown) to the circuit board  36  and a remote power source. In the embodiment shown, the first and second passageways  56 ,  58  are configured to direct a power cable over, along, or through the yoke  14 , in order to prevent the power cable from interfering with the clinician&#39;s line of sight or freedom of movement. More specifically, the first passageway  56  may house a portion of the power cable, and the second passageway  58  may receive a set screw for engaging a jacket of the power cable in order to provide strain relief. However, other configurations of the first and second passageways  56 ,  58  may be used depending on the particular application. In one embodiment, only a single passageway may be included in the second housing  34 . 
         [0023]    In one embodiment, the singlet lens  22  may be positioned at or near the distal opening  42 , and may have a diameter of between about 10 mm and about 14 mm. For example, the singlet lens  22  may have a diameter of about 10 mm. The singlet lens  22  may have a thickness of between about 1 mm and about 3 mm. For example, the singlet lens  22  may have a thickness of about 2 mm. 
         [0024]    In one embodiment, the doublet lens  20  may be achromatic, and may comprise first and second simple lenses  20   a ,  20   b . As shown, the doublet lens  20  is positioned between the LED  24  and the singlet lens  22 . In one embodiment, the doublet lens  20  may have a diameter of between about 3 mm and about 7 mm. For example, the doublet lens  20  may have a diameter of about 5 mm. The doublet lens  20  may have a thickness of between about 2 mm and about 4 mm. For example, the doublet lens  20  may have a thickness of about 3 mm. 
         [0025]    The lenses  20 ,  22  and this arrangement of lenses  20 ,  22  relative to the LED  24  may produce a substantially uniform light beam and a substantially round, homogenous light spot at the target. Moreover, by positioning the doublet lens  20  near the LED  24 , the doublet lens  20  may have a relatively small diameter, such as by comparison to the diameter of the opening  42 , for example. Thus, the doublet lens  20  may be constructed of a relatively small amount of glass, and therefore be relatively lightweight, at least by comparison to a hypothetical doublet lens of similar configuration positioned at the opening  42 . 
         [0026]    The diameter of the housing  12  at the distal opening  42  may be relatively small compared to other headlights, wherein a doublet lens is typically positioned farther away from the light source (e.g. at or near an opening distal the light source). As a consequence, the diameter of the housing  12  at the distal opening  42  may be smaller relative to other headlights. By way of example and not limitation, the diameter of the housing  12  at the distal opening  42  may be from about 9 mm to about 14 mm, while the diameters of housings of other comparable headlights at their distal openings are typically from about 15 mm to about 17 mm, which may represent an approximately 10% decrease in diameter of the housing  12  at the distal opening  42  compared to other headlights. Thus, by positioning the doublet lens  20  within the housing  12  at a position away from the opening  42  and near the LED  24 , the diameter of the doublet lens  20  may be minimized, reducing the overall weight of the housing  12 . As described above, the headlight assembly  10  may reduce fatigue and so improve comfort by utilizing lightweight components and, more particularly, a doublet lens  20  having a relatively small diameter. 
         [0027]    While the present invention has been illustrated by a description of various preferred embodiments and while these embodiments have been described in some detail, it is not the intention of the inventor to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The various features of the invention may be used alone or in any combination depending on the needs and preferences of the user.