Abstract:
A medical headlamp having a front from which light is selectively emitted. The headlamp includes a beam origination portion that produces a light beam and an iris assembly, positioned in front of the beam origination portion, having a user accessible actuator and an iris, responsive to the actuator to block a user-selectable portion of the light beam. The iris is also responsive to the actuator to block none of the light beam, for maximum efficiency, when a user so selects.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of application Ser. No. 13/972,489, filed Aug. 21, 2013, which in turn claims priority from provisional application Ser. No. 61/822,493, filed May 13, 2013. Both of the above noted applications are hereby incorporated by reference as if fully set forth herein. 
     
    
     BACKGROUND 
       [0002]    A medical headlamp assembly is a critical part of the surgeon&#39;s suite of tools, as it is of great importance that a surgeon can clearly see in the operating theater. The ideal headlamp would be easily portable, light and comfortable to wear for at least four hours. Further, it would have battery power, mounted on the head strap, sufficient to last four hours from one charge, thereby eliminating the necessity of waist mounted battery pack and cables connecting this pack to the lamp, which are uncomfortable and complicate antiseptic protocol. Further the ideal headlamp assembly would create a bright beam of light that was homogenous and uniform in brightness and color, from edge-to-edge, directly along the surgeon&#39;s line of sight, without obscuring his or her line of sight. Also, it would be entirely silent, easily adjustable in position and would not be susceptible to infection by mold or any other sort of organism. 
         [0003]    Unfortunately, these criteria are not only difficult to meet, but are also frequently at odds with each other. For example, although it is better to have a bright light, this creates more heat, which must be safely expressed from the lamp. It is helpful in the elimination of heat to make the lamp bigger, but doing so is likely to cause it to obscure the surgeon&#39;s line of sight and add unbearable weight. Another option for expressing heat would be to provide a fan, but this creates a sound, which may be difficult for the surgeon to tolerate. To permit longer battery life it would be helpful to have higher capacity batteries, but doing so makes the assembly heavier and more difficult for the surgeon to tolerate for a long period of time. The batteries could be placed in a waist pack, but doing so requires an electrical line extending from an aseptic area, about the waist underneath the scrubs (anything under the neck is a “sterile” area), to a non-sterile area, on the surgeon&#39;s head. This arrangement complicates aseptic protocol. 
         [0004]    There is a currently available headlamp assembly that mounts batteries on the headband and that has batteries that can be swapped out, one at a time, for extended surgical periods. The light produced by this headlamp is on the order of 166 lumens in intensity. For many types of surgery, for example where a deep cavity that has been opened up inside a patient requires illumination, a higher intensity lamp is desirable. 
       SUMMARY 
       [0005]    The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods, which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above-described problems have been reduced or eliminated, while other embodiments are directed to other improvements. 
         [0006]    In a first separate aspect, the present invention may take the form of a medical headlamp having a front surface from which a lamp light beam is emitted. The headlamp has a high efficiency light source producing a beam having a 3 dB beam width of greater than 100° and an annular light block, defining an annulus and placed immediately in front of the high efficiency light source, a light beam extending from the light block. Also, an optical assembly is positioned to receive light from the high efficiency light source assembly and produce a lamp light beam emitted from the front surface of the lamp. Further, a housing supports the light source and the optical assembly and an electrical conductor connects to the light source, for supplying electricity to the light source. Finally, the optical assembly includes an adjustable iris assembly including a user accessible actuator and an iris that is adjustable by the actuator, to be retracted away, thus leaving unaffected the light beam from the light block, or to be tightened to block a portion of the light beam from the annular light block, thus producing a thinner lamp light beam. 
         [0007]    In a second separate aspect, the present invention may take the form of a medical headlamp having a front from which light is selectively emitted. The headlamp includes a beam origination portion that produces a light beam and an iris assembly, positioned in front of the beam origination portion, having a user accessible actuator and an iris, responsive to the actuator to block a user selectable portion of the light beam. The iris is also responsive to the actuator to block none of the light beam, for maximum efficiency, when a user so selects. 
         [0008]    In a third separate aspect, the present invention may take the form of a lamp having a front from which light is selectively emitted. The lamp includes a beam origination portion, which produces a light beam and a beam modification portion, which can be controlled to block a selectable portion of the light beam and can also be controlled to block none of the light beam, for maximum efficiency. Further, when the beam modification portion is controlled to block none of the light beam, the lamp produces a beam of more than 90 lumens per watt of electrical power delivered to the lamp. 
         [0009]    In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following detailed descriptions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Exemplary embodiments are illustrated in referenced drawings. It is intended that the embodiments and figures disclosed herein be considered illustrative rather than restrictive. 
           [0011]      FIG. 1  shows an exploded view of a medical headlamp, according to the present invention. 
           [0012]      FIG. 2  shows a sectional view of the medical headlamp of  FIG. 1 . 
           [0013]      FIG. 3  is an illustration of the effect of the barrel adjustment on the light beam diameter. 
           [0014]      FIG. 4  is a graph of the intensity of a light spot created by a preferred embodiment of a headlamp, as described herein. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Definitions 
       [0015]    For the purposes of this application, a “high efficiency light source” is an electrically powered light source having a light emitting surface area of less than 50 mm 2  that produces light at a rate of greater than 50 lumens per watt of input power and at a rate greater than 30 lumens per square millimeter of light emitting area. This term does not include packaging or a lens. If these items are included the phrase used is “high efficiency light source assembly”. 
         [0016]    A light emitting diode (LED), as used in the application, refers to a solid-state electrical device and does not include any lens or packaging. Others sometimes refer to this element as a “die,” A light emitting diode assembly, includes packaging and a lens. 
         [0017]    The term “most” as used in this application, means more than 50%. 
         [0018]    The term “light” as used in this application refers to visible light. 
         [0019]    The “front” of the medical lamp is the side from which light is emitted. The “longitudinal dimension” extends from front to back. 
         [0020]    The term “headlamp” is used to refer to the entire lamp or illuminating assembly, as shown in  FIGS. 1 and 2 , but not the headband (which may also be referred as “head strap”) or the linkage, which together with headlamp form a headlamp assembly. 
         [0021]    Referring to  FIGS. 1 and 2 , a high-efficiency medical headlamp  10  is shown, of the type that could be attached to a head strap assembly and used by a surgeon to light the surgical theater, or by a medical professional, in general, to illuminate an area of interest. This headlamp  10  is very efficient, producing a relatively high volume of light for the amount of electrical power consumed, thereby permitting the use of batteries mounted on the headband assembly, as opposed to mounted on a waist pack, with electrical cabling connecting the battery to the lights. 
         [0022]    The headlamp  10  includes an aft barrel  12 , which houses a round piece of flex circuit  14 , upon which are defined conductive traces  16 , adapted to drive a light emitting diode (LED) assembly  18 , more generally termed “a high efficiency light assembly.” Aft barrel  12  defines a channel  20  ( FIG. 2 ) for an electrical wire to pass through, to connect a supply of electricity to traces  16 . 
         [0023]    A portion of LED assembly  18  extends through an aperture  22  in a prime lens holder  30 , and also extends through an aperture  24  in an annular light block  32 , which has a thickness on the order of 25 μm and which blocks the peripheral light produced by assembly  18 , thereby creating a crisp outline for the spot of light produced by headlamp  10 . In front of and surrounding the portion of the high efficiency light source  18  that protrudes through aperture  24  is a prime lens  34  having a convex rear surface ( FIG. 2 ). Immediately in front of prime lens  34  an iris  36  acts to permit an adjustment by actuator  38 , to create a thinner light beam, which will be described in more depth, below. In front of iris  36  is an exit lens holder  50 , containing an exit lens  52 . An outer ring  54  surrounds exit lens holder  50 . 
         [0024]    The iris actuator  38  fits through a circumferential groove  60  defined in aft barrel  12  and further extends into straight forward and backward groove  62 , defined in outer ring  54 . Similarly, a groove follower  64  on exit lens holder  50  protrudes through a groove  66  on aft barrel, and also extends into groove  62  in outer ring  54 . The result of this arrangement is that as outer ring  54  is rotated, both actuator  38  and groove follower  64  are moved circumferentially. In addition, over part of the travel of outer ring  54 , groove follower  64  is moved forward or backward, as slot  66  is diagonal. This changes the focus of the light beam produced by headlamp  10 . Over the remainder of the travel of outer ring  54 , groove follower  64  is only moved circumferentially, which has no effect on the optical characteristics of headlamp  10 . 
         [0025]    Referring to  FIG. 3 , in configuration  70  outer ring is at the clockwise end of its travel, which causes actuator  38  to be at the extreme right end of groove  60  (from the perspective of an observer looking at groove  60 ). This causes iris  36  to be in its narrowest aperture state, creating a very thin light beam  80 . Groove follower  64  is also at the extreme right hand side of groove  66 , causing exit lens  52  to be at the extreme far forward extent of its range of motion. This option is sometimes required, particularly by ear, nose and throat specialists. In configuration  72 , both actuator  38  and follower  64  are at the mid-range of their circumferential motion. This increases the aperture defined by iris  36  enough so that the beam width is defined by annular light block  24 . At the same time, exit lens is maintained in its far forward position, defocusing the beam to create a wider, although less well focused light spot  82 . Finally, in configuration  74 , the actuator  38  and follower  64  are at the extreme left hand extent of their travel, causing iris to be definitively not affecting the beam  84 , which is shaped entirely by annular light block  24 . The exit lens  52 , however, is brought back in to create a tight, well-focused beam with sharp boundaries. Accordingly, a full range of beam widths are permitted, while removing the iris entirely from engagement with the light beam for the wide beam geometries, thereby resulting in a more efficient system, when it is needed most, for the illumination of deep cavity surgery. 
         [0026]    The placement of the light block  32  together with its 25 μm thickness, creates a sharp boundary about the light, and ultimately creates a crisp spot of light, at the typical 80-100 mm (16-18 in) working distance. Table 1 shows the characteristics of LED assembly  18  for four differing embodiments. In an alternative preferred embodiment an LED assembly is used that is similar to the Oslon Square LED assembly, but includes more than one LED die, and in another preferred embodiment more than one LED assembly is used. 
         [0000]    
       
         
               
             
               
               
               
               
             
               
               
             
               
               
               
               
               
             
               
               
             
               
               
               
               
               
             
               
               
             
               
               
               
               
               
             
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 LED Assemblies Used in Various Embodiments 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                   
                 Further 
                   
               
               
                   
                 Manufacturer 
                 Designation 
                   
               
               
                   
                 Designation 
                 Class (Color) 
                 LED Beam Angle 
               
               
                   
               
               
                 LED Assembly of Emb. 1 
                 Oslon Square 
                 PC 
                 120 
               
               
                 LED Assembly of Emb. 2 
                 Oslon Square 
                 EC 
                 120 
               
               
                 LED Assembly of Emb. 3 
                 Oslon Square 
                 CC 
                 120 
               
               
                 LED Assembly of Emb. 4 
                 Oslon Square 
                 EQW 
                 120 
               
               
                   
               
             
          
           
               
                   
                 Lumen Output 
               
             
          
           
               
                 Current Applied 
                 750 mA 
                 1 A 
                 1.2 A 
                 1.5 A 
               
               
                   
               
               
                 LED Assembly of Emb. 1 
                 252-346 
                 312-429 
                 372-511 
                 408-561 
               
               
                 LED Assembly of Emb. 2 
                 220-294 
                 273-364 
                 325-434 
                 357-476 
               
               
                 LED Assembly of Emb. 3 
                 189-271 
                 234-336 
                 279-401 
                 306-440 
               
               
                 LED Assembly of Emb. 4 
                 294-409 
                 364-507 
                 434-604 
                 476-663 
               
               
                   
               
             
          
           
               
                   
                 Voltage 
               
             
          
           
               
                 Current Applied 
                 750 mA 
                 1 A 
                 1.2 A 
                 1.5 A 
               
               
                   
               
               
                 LED Assembly of Emb. 1 
                 3.08 
                 3.15 
                 3.2 
                 3.28 
               
               
                 LED Assembly of Emb. 2 
                 3.08 
                 3.15 
                 3.2 
                 3.28 
               
               
                 LED Assembly of Emb. 3 
                 3.08 
                 3.15 
                 3.2 
                 3.28 
               
               
                 LED Assembly of Emb. 4 
                 3.08 
                 3.15 
                 3.2 
                 3.28 
               
               
                   
               
             
          
           
               
                   
                 Wattage 
               
             
          
           
               
                 Current Applied 
                 750 mA 
                 1 A 
                 1.2 A 
                 1.5 A 
               
               
                   
               
               
                 LED Assembly of Emb. 1 
                 2.31 
                 3.15 
                 3.84 
                 4.92 
               
               
                 LED Assembly of Emb. 2 
                 2.31 
                 3.15 
                 3.84 
                 4.92 
               
               
                 LED Assembly of Emb. 3 
                 2.31 
                 3.15 
                 3.84 
                 4.92 
               
               
                 LED Assembly of Emb. 4 
                 2.31 
                 3.15 
                 3.84 
                 4.92 
               
               
                   
               
             
          
           
               
                   
                 Lm/Watt @ max Im 
               
             
          
           
               
                 Current Applied 
                 750 mA 
                 1 A 
                 1.2 A 
                 1.5 A 
               
               
                   
               
               
                 LED Assembly of Emb. 1 
                 150 
                 136 
                 133 
                 114 
               
               
                 LED Assembly of Emb. 2 
                 127 
                 116 
                 113 
                  97 
               
               
                 LED Assembly of Emb. 3 
                 117 
                 107 
                 104 
                  89 
               
               
                 LED Assembly of Emb. 4 
                 177 
                 161 
                 157 
                 135 
               
               
                   
               
             
          
         
       
     
         [0027]    The effect of the above detailed design is a medical headlamp  10 , that can be incorporated into an assembly with batteries mounted on the head strap assembly, and without a fan to provide forced air cooling, but which produces a brighter beam than previously available headlamp assemblies of this sort. The beam produced, in one preferred embodiment, has a light volume of 413 lumens with a color rendering index of at least 65. The beam is emitted relatively evenly from the 23 mm diameter front surfaces of the exit lens  52 , and spreads out by 4.19 degrees in all directions as the beam advances. Referring to  FIG. 4 , a one (1) Amp lamp, as described above, where the voltage drop from the batteries is 3.4 Volts, produces a spot of light at 45.7 cm graph in  FIG. 4  says mm (18 inches) as shown. With a bright central area, about 52 mm wide at all above 50,000 lux at a color rendering index (CRI) of greater than 65. A ring of about 10 mm width surrounds this, where the light intensity declines from 50,000 lux to 25,000 lux. At the edges of the light beam, the brightness drops off by 20 dB in 0.5°. The lamp is operable in an ambient temperature of up to 30° Celsius, with no fan to cool the lamp. 
         [0028]    When iris  36  is opened up so that it does not block any of the light from LED  18 , the proportion of this light that is emitted in the light beam from the exit lens  52  is greater than in prior art systems. This is because: 1) the distance between the LED assembly  18  and the prime lens  34  is shortened to virtually nothing, as the LED assembly  18  protrudes into a concavity in the prime lens  34 ; 2) the annular light block  32  sits on the lens of the LED assembly  18 , sufficiently far back that it blocks only a small proportion of the light. In one preferred embodiment, 70% of the light produced by LED assembly  18  is emitted from the exit lens  52  as a light beam. Alternative preferred embodiments emit anywhere from 50% to 70% of the light produced by the LED assembly  18  out of exit lens  52 . This compares favorably with prior art systems where less than 45% of the light produced by the light source is emitted in the beam. In a preferred embodiment the light beam produced from exit lens  52  has a volume of 114 to 161 lumens for every watt of power applied to LED assembly  18 . In one alternative preferred embodiment this figure ranges from 90 lumens of output light per watt to 161 lumens of output light per watt. Many prior art systems include an iris but do not include any part analogous to light block  32 , so that the iris is always blocking a portion of the light beam produced by the light source. Incorporating both the annular light block  32  and the iris  36 , makes it possible to create a very high intensity beam, with minimum battery drain when the iris is opened up wide enough so that it blocks no light, but also to have a thin beam, when warranted. 
         [0029]    This device greatly eases the task of the surgeon, who may now have an adequately bright and wide spot light beam for deep cavity surgery, without the need for the distracting noise and cumbersome extra weight of a fan and without the need of any power cable traversing from a sterile to a non-sterile zone. The same lamp may, in its narrow beam state of adjustment, be used by an ear, nose and throat specialist. 
         [0030]    While a number of exemplary aspects and embodiments have been discussed above, those possessed of skill in the art will recognize certain modifications, permutations, additions, and sub-combinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.