Abstract:
An aiming sight has a base, at least one light emitting element on the base, and a clear cover over the light emitting element. The light emitting element is made of light gathering plastic combined with self-luminous microspheres. When ambient light is present, the light emitting element functions as a light gathering rod that emits light from the back end. When no light is present, the light emitting element is self-luminous.

Description:
[0001]    This application claims the benefit under 35 U.S.C. §119(e) of the U.S. provisional patent application No. 61/259,270 filed Nov. 9, 2009. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to aiming sights and more particularly to sighting devices with self-luminous microspheres for bright light, low light and dark conditions. 
       BACKGROUND ART 
       [0003]    Modern firearms are inherently very accurate. The ability to shoot accurately depends on accurate pointing or aiming, and often requires rapid acquisition of the target. Known sights commonly have a front sight in the form of a small bead sight near the muzzle or front of the firearm barrel. Such sights can also have a rear sight near the breach or rear of the firearm barrel. 
         [0004]    Conventional bead sights have several shortcomings. Bead sights are difficult to see in low light conditions and against dark backgrounds. One improvement to front sights relative to the bead sight is the use of a small artificial light source to replace the bead sight. The light source can be electrical or photo chemical. Front sights with artificial light sources are relatively complex and require periodic replacement of the light or power source. 
         [0005]    Another improvement is the use of a light-gathering tube or rod, generally of a colored plastic material, to replace the bead sight. Such light-gathering tubes have a length many times the cross sectional dimension, and thereby have a peripheral surface area much greater than the end area. Light is absorbed through the peripheral surface and emitted through the end of the tube. A front sight with a light-gathering tube is easily seen in bright light and low light conditions, and against a dark background. However, such sights are not readily visible in dark conditions. 
         [0006]    A further improvement is the combination of a light-gathering tube or rod with a radioluminescent capsule at or in the forward end of the light-gathering rod. In daylight and low light conditions, the light-gathering tube gathers ambient light and directs the light rearwardly, providing a bright dot for aiming. In the dark, the light from the radioluminescent capsule is guided through the light-gathering tube to provide a bright dot for aiming. The radioluminescent capsule is generally a short glass tube that is coated on the inside with a phosphor and contains a radioactive gas such as tritium. Firearm sights can experience high shock loads from firing of the weapon. The radioluminescent capsules must be carefully mounted to prevent breakage and escape of the radioactive gas. Another problem with known devices of this kind is migration or separation of the radioluminescent capsule from the light-gathering tube due to adhesive failure. 
         [0007]    U.S. Pat. No. 4,677,008 to Webb and U.S. Patent Publication No. 20070200074 to Kohnen each disclose radioluminescent microspheres. Webb and Kohnen both disclose that the microspheres can be “disposed on a surface to form signs, markers, indicators and the like” and “disposed in a transparent binder to form a luminous paint”. 
       DISCLOSURE OF THE INVENTION 
       [0008]    A sighting device includes a base, an elongated light emitting element, mounted on the base and a cover. The light emitting element has a periphery through which light is absorbed and a rearwardly facing back end through which light is emitted. A plurality of light emitting microspheres are embedded in the light emitting element. The light emitting element is a light gathering rod when ambient light is present and is self-luminous when no light is present. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Details of this invention are described in connection with the accompanying drawings that bear similar reference numerals in which: 
           [0010]      FIG. 1  is a perspective view of a front sight embodying features of the present invention. 
           [0011]      FIG. 2  is an exploded, partially cutaway view of the front sight of  FIG. 1 . 
           [0012]      FIG. 3  is a perspective view of a rear sight embodying features of the present invention. 
           [0013]      FIG. 4  is an exploded, partially cutaway view of the rear sight of  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    Referring to  FIGS. 1 and 2 , a front sight  11  embodying features of the present invention includes a base  14 , a light emitting element  15  and a cover  16 . The base  14  has a lower mounting portion  18  and an upper element holder  19  attached on top of the mounting portion  18 . The base  14  is preferably made of metal or an opaque plastic. The mounting portion  18  shown is sized and shaped to mount near the muzzle of a handgun. Other configurations of the mounting portion  18  can be used for other weapons. 
         [0015]    Describing the specific embodiments herein chosen for illustrating the invention, certain terminology is used which will be recognized as being employed for convenience and having no limiting significance. For example, the terms “front”, “back”, “right”, “left” “vertical”, “horizontal, “lateral”, “longitudinal”, “upper” and “lower” refer to the illustrated embodiment in its normal position of use. Further, all of the terminology above-defined includes derivatives of the word specifically mentioned and words of similar import. 
         [0016]    The element holder  19  has an elongated, rectangular bottom portion  21  extending from a front end  22  to a spaced back end  23 . A front wall  25  projects upwardly from the bottom portion  21  at the front end  22 , and a back wall  26  projects upwardly from the bottom portion  21  at the back end  23 . The bottom portion  21  has an upwardly facing top surface  27  with an upwardly opening element channel  28  that extends from the front wall  25  to the back wall  26 . A front element aperture  30  extends through the front wall  25  and a back element aperture  31  extends through the back wall  26 . The front element aperture  30 , the element channel  28  and the back element aperture  31  are aligned with each other, and sized and shaped to the receive the light emitting element  15 . 
         [0017]    The light emitting element  15  shown is generally an elongated cylinder with a front end  33 , a spaced back end  34 , an enlarged back section  35  at the back end  34 , and a peripheral surface  36 . The peripheral surface  36  is preferably smooth and polished to receive light. The back end  34  is preferably flat or convex, and textured to emit light rearwardly. A groove  37  extends around the peripheral surface  36  near the front end  33 . The light emitting element  15  shown is injection molded and therefore can made in any selected shape. The light emitting element  15  can also be extruded, but extrusion limits the shapes available. 
         [0018]    The light emitting element  15  is made of a mixture of translucent plastic and light emitting microspheres  40 . The plastic is generally a bright color such as green, crimson, yellow or orange. The microspheres  40  are generally evenly and randomly distributed throughout the light emitting element  15 . The microspheres  40  are generally hollow microspheres of glass or polymer containing a radioactive gas, such as tritium, and particles of a phosphor that emit light in response to radioactive decay in the gas. 
         [0019]    Ambient light is absorbed through the peripheral surface  36  and emitted through the back end  34 . Light from the microspheres  40  is also emitted through the back end  34 , illuminating the back end  34  even when little or no ambient light is present. The concentration or relative volume of the microspheres  40  in the light emitting element  15  can be selected to tailor the relative brightness of the back end  34  between bright and dark light conditions. 
         [0020]    The cover  16  is made of a clear plastic and is an elongated, partial cylinder shape sized to extend from the front wall  25  to the back wall  26 . The cover  16  has an internal channel  41  sized to receive the light emitting element  15 . The cover  16  is preferably molded over the base  14  after the light emitting element  15  is assembled to the base  14 , so that the cover  16  fills the groove  37  and locks the light emitting element  15  to the base  14 . In addition to retaining the light emitting element  15  to the base  14 , the cover  16  also protects the light emitting element  15  from external damage. 
         [0021]    Referring now to  FIGS. 3 and 4 , a rear sight  44  embodying features of the present invention includes a base  46 , a pair of light emitting elements  47  and a cover  48  for each light emitting element  47 . The base  46  includes a lower mounting portion  51  and an upper body  52  attached on top of the mounting portion  51 . The base  14  is preferably made of metal or an opaque plastic. The mounting portion  51  shown is sized and shaped to mount near the breech of a handgun. Other configurations of the mounting portion  51  can be used for other weapons. 
         [0022]    The body  52  includes a generally square lower section  54  and a pair of spaced element holders  55  that project upwardly from the lower section  54 . The lower section  54  defines the bottom of a sight channel  56 , and the element holders  55  define the sides of the sight channel  56 . 
         [0023]    Each element holder  55  has an elongated, intermediate section  58  on the lower section  54 . The intermediate section  58  extends from a front end  59  to a spaced back end  60 . A back wall  62  projects upwardly from the intermediate section  58  at the back end  60 . The intermediate section  58  has an upwardly facing top surface  63  with an upwardly opening element channel  64  that extends forwardly from the back wall  62 . A back element aperture  66  extends through the back wall  62 . The element channel  64  and the back element aperture  66  are aligned with each other. An intermediate element aperture  67  extends downwardly from the element channel  64  into the intermediate section  58 . The element channel  64 , the back element aperture  66  and the intermediate element aperture  67  are sized and shaped to the receive the light emitting element  47 . 
         [0024]    The light emitting element  47  shown has an elongated cylindrical first section  69  with a front end  70  and a spaced back end  71 , and a cylindrical second section  73  that projects transversely from the first section  69  intermediate the first and second ends  70  and  71 . The first section  69  has a peripheral surface  74  that is preferably smooth and polished to receive light. The back end  71  is preferably flat or convex, and textured to emit light rearwardly. The light emitting element  47  shown is injection molded and therefore can made in any selected shape. The light emitting element  47  can also be extruded, but extrusion limits the shapes available. The first section  69  fits into the element channel  64  and the back element aperture  66 , with the second section  73  projecting downwardly into the intermediate element aperture  67 . 
         [0025]    The light emitting element  47  is made of a mixture of translucent plastic and light emitting microspheres  40 . The plastic is generally a bright color such as green, crimson, yellow or orange. The microspheres  40  are generally evenly and randomly distributed throughout the light emitting element  47 . 
         [0026]    Ambient light is absorbed through the peripheral surface  74  and emitted through the back end  71 . Light from the microspheres  40  is also emitted through the back end  71 , illuminating the back end  71  even when little or no ambient light is present. The concentration or relative volume of the microspheres  40  in the light emitting element  47  can be selected to tailor the relative brightness of the back end  71  between bright and dark light conditions. 
         [0027]    Each cover  48  is made of a clear plastic and is sized and shaped to fit over the top surface  63  of the intermediate section  58  of the element holder  55  and has an internal channel  76  sized to fit over the light emitting element  47 . The cover  48  is preferably molded over the base  46  after the light emitting element  47  is assembled to the base  46 , so that the cover  48  retains the light emitting element  47  to the base  46 . In addition to retaining the light emitting element  47  to the base  46 , the cover  48  also protects the light emitting element  47  from external damage. 
         [0028]    When the front sight  11  and rear sight  44  are mounted on a firearm, the user aligns the front sight  11  in the sight channel  56  of the rear sight  44 . The light emitting elements  15  and  47  function as light gathering rods or tubes during bright light and low light conditions, and as self-luminous light source in dark conditions. The microspheres are capable of withstanding 5,000 psi of crush force. Embedding the microspheres  40  into the light emitting elements  15  and  47  eliminates the adhesive failure problems associated with devices that use a separate self-luminous capsule, and eliminates the risk of breakage of a separate self-luminous capsule. Eliminating the separate self-luminous capsule allows the front and rear sights  11  and  44  to have shorter bases  14  and  46 . 
         [0029]    Although the present invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made by way of example and that changes in details of structure may be made without departing from the spirit thereof.