Abstract:
The present invention consists of an optical mirror element to be used in combination with a light source. Light from a light source contained within the mirror element shank provides illumination in front of and behind the mirror head. In this way, for example, the invention can be used in dentistry both for illuminated, indirect vision in the mouth and as an illuminated cheek or tongue retractor. The invention can be used in combination with any suitable light source including, but not limited to, a conventional lamp, a light emitting diode, or a light pipe.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not Applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention relates to mirrors used for inspection and examination. More specifically, the invention relates to a dental optical mirror element to be used in combination with a handle and a light source. 
         [0004]    Hand held dental mirrors have long been used in the field of dentistry and are well known to those skilled in the art. Dental mirrors are used to view areas of the mouth which are not easily viewable by direct line of sight. 
         [0005]    Dental mirrors have been combined with a light source. Combining a dental mirror with a light source greatly increases the ability to view relatively dark areas of the mouth which are not visible by direct line of sight. Examples of such mirrors are disclosed in U.S. Pat. Nos. 1,747,009 to Jordan; 2,428,975 to Lamb; 3,638,013 to Keller; 5,139,421 to Verderber; 5,457,611 to Verderber; 6,443,729 to Watson; 6,702,577 to Wong and 7,066,734 to Cooper. 
         [0006]    The illuminated dental mirror disclosed in U.S. Pat. No. 5,139,421 to Verderber is known to be the most successful illuminated mirror marketed to dentists. The Verderber mirror was long produced and marketed by Welch-Allyn, Inc., of Skaneateles, N.Y. and is currently produced and marketed by Integra LifeSciences Holdings Corporation&#39;s Miltex Dental business of York, Pa. 
         [0007]    In U.S. Pat. No. 5,139,421 Verderber discloses a mirror element including a light transmitting shank. While the Verderber mirror has demonstrated commercial success, it is problematic; being relatively expensive to manufacture and relatively inefficient in terms of light transmission. 
         [0008]    The shank of the Verderber mirror must be relatively thick in order to admit adequate light and transmit adequate light. As for example, the Verderber mirror is manufactured with a shank diameter of 0.25 inches. It has been discovered that a shank of this diameter is prone to gas bubble inclusions: after molten plastic is injected into a mold, the surface of the cylindrical shank hardens first. As the still molten plastic material within the shank cools, it shrinks, creating gas bubble inclusions. Gas bubble inclusions within the shank are a major fault as they interfere with light transmission and significantly reduce the efficiency of the instrument. To reduce the incidence of gas bubble inclusions within the shank of the Verderber mirror element, high mold pressure must be maintained and the shank must be cooled slowly. Operating an injection mold at high pressure reduces the life of the mold. Cooling the mold slowly increases the molding cycle time. Relatively short mold life and relatively slow molding cycles contribute significantly to the cost of manufacturing the Verderber mirror. It would be ideal to provide an optical mirror element having high quality light distribution, but which could be molded using low mold pressure and fast molding cycles. 
         [0009]    The volume of plastic material comprising the shank of the Verderber mirror element accounts for about two thirds of the plastic material in the mirror element and is significant in terms of materials cost. Reducing the volume of plastic material comprising the shank of the Verderber mirror element would result in a considerable reduction in part cost. It would be ideal to provide a mirror element using a relatively small volume of plastic material, thereby significantly reducing the cost to produce said mirror element. 
         [0010]    Some volume of light traveling through the shank of the Verderber mirror is lost as a result of interference with micro-bubbles and inclusions. As discussed in greater detail above, the Verderber shank is prone to gas bubble inclusions. Although high mold pressure and relatively slow molding cycles reduce the incidence of major gas bubbles, micro-bubbles are inevitably present within said shank. Further, inclusions of dust, oils and other unknown materials are inevitably present within said shank. A portion of the light transmitted through the shank strikes these inclusions and is thereby scattered, reducing the efficiency of the instrument. It would be ideal to provide a mirror element in which the distance light is transmitted through molded optical plastic is minimized. 
       BRIEF SUMMARY OF THE INVENTION 
       [0011]    The present invention consists of an optical mirror element to be used in combination with a handle and a light source. The shank of the optical mirror element is a hollow cylinder or tube designed to accept and contain a light source. The invention can be used in combination with any suitable light source including, but not limited to a fiber optic light pipe, conventional lamp or a light emitting diode. 
         [0012]    Light from a light source contained within the optical mirror element shank is directed toward a prism formed between the mirror head and the shank. Some light entering the prism is internally reflected and exits the face of the prism to provide illumination in front of the mirror head. Some light entering the prism exits the heel of the prism to provide illumination behind the mirror head. In this way, for example, the invention can be used in dentistry both for illuminated, indirect vision and as an illuminated cheek or tongue retractor. 
         [0013]    In general, the object of the present invention is to provide a disposable optical mirror element having the high quality illumination characteristics of the mirror element disclosed in U.S. Pat. No. 5,139,421 to Verderber, but which is more efficient in terms of light transmission and which can be manufactured at lower cost. 
         [0014]    An advantage of the present invention is that the optical mirror element described herein requires a relatively small volume of plastic material, thereby reducing the cost to manufacture the part. 
         [0015]    A further advantage of the present invention is that it requires relatively thin wall sections, thereby allowing the optical mirror element to be molded using relatively fast molding cycles, further reducing the cost to manufacture the part. 
         [0016]    A further advantage of the present invention is that it reduces light transmission through molded plastic material, thereby increasing the optical efficiency of the part. 
         [0017]    These and other objects, features and advantages will become readily apparent from the following Detailed Description, which should be read in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0018]    While the specification concludes with claims particularly pointing out and distinctly claiming the present invention, it is believed the same will be better understood from the following description taken in conjunction with the accompanying drawings in which: 
           [0019]      FIG. 1  is a frontal view of the optical mirror element. 
           [0020]      FIG. 2  is an elevation side view of the mirror element in combination with a mirror handle. 
           [0021]      FIG. 3  is a cross-sectional side view of the optical mirror element specifically depicting the mirror head, prism, and shank. 
           [0022]      FIG. 4  is a partial view of the optical mirror element shown in  FIG. 3 , specifically showing a light source contained within the shank and illustrating the optical effect the prism formed within the heel of the shank. 
           [0023]      FIG. 5  is an elevation view of a dental mirror handle including a light emitting diode. 
           [0024]      FIG. 6  is an elevation view of a dental mirror handle including a fiber optic light pipe. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    For the purpose of promoting an understanding of the principles of the present invention, reference will now be made to the embodiments illustrated in the drawing (where like numerals indicate like elements of the invention) and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. 
         [0026]    An optical mirror element  10  is shown in  FIGS. 1 ,  2  and  3 . In  FIG. 2  optical mirror element  10  comprises the distal portion of a dental mouth mirror. Optical mirror element  10  comprises three major segments, including, a head  14 , a prism  16  and a shank  18 . 
         [0027]    Head  14 , prism  16  and shank  18  are manufactured as a single unit from a light conductive material such as a plastic acrylic. Head  14  is generally disc-shaped and is inclined at a predetermined angle to shank  18 . Within the front surface of mirror head  14 , a recess is provided into which a conventional round mirror  20  may be inset or cemented as illustrated in  FIG. 3 . Alternately, a reflective material may be applied directly to the mirror head  14  such that said mirror head  14  can be used for indirect viewing. 
         [0028]    Prism  16  is generally triangular in cross section as shown in  FIGS. 3 and 4 . Prism  16  forms the junction between the head  14  and the shank  18  and comprises three major segments, including a base  22 , a heel  24  and a face  26 . Referring now to  FIGS. 3 and 4 , face  26  is a flattened or planar surface at the junction of mirror head  14  and shank  18 , and is generally parallel to the longitudinal axis of the shank  18 . Heel  24  is a flattened planar surface at the junction of mirror head  14  and shank  18 . Heel  24  is generally the same angle at which head  14  is inclined in relation to the longitudinal axis of shank  18 . Base  22  is a flattened planar surface adjacent to said face  26  and said heel  24 . Base  22  is generally perpendicular to face  26  and is inclined in relation to heel  18 . 
         [0029]    Shank  18  is a hollow cylinder or tube having a proximal end and distal end. The proximal end of shank  18  terminates in the base  22  of prism  16 . The distal end of hollow tubular shank  18  is open such that shank  18  can be removably inserted onto male receptacle  28  of handle  30  with the longitudinal axis of shank  18  parallel to the longitudinal axis of handle  30  as shown in  FIG. 2 . Optical mirror element  10  can be used with any suitable handle  30  having a light source. Said light source may be a conventional lamp  32  as shown in  FIG. 4 , light emitting diode  34  as shown in FIG.  5 ., or a fiber optic light rod  36  as shown in  FIG. 6 . Because the optical mirror element  10  described herein is separable from handle  30 , said optical mirror element  10  can be easily and effectively sterilized, disinfected or replaced. When shank  18  is in place on handle  30 , the base  22  of prism  16  is in close proximity to light source  32 ,  34 ,  36  comprising the distal end of male receptacle  28 . 
         [0030]    When the present invention is in use, light from said light source  32 ,  34 ,  36  is generally directed through the base  22  of prism  16 . As for example,  FIG. 4  shows a conventional lamp  32  contained within shank  18  where light is directed through the base  22  of prism  16  schematically illustrated by arrows representing light beams designated A and B. Light is transmitted through prism  16  with some volume of the light designated as A in  FIG. 4  being emitted from heel  24  and some volume of light designated as B in  FIG. 4  being internally reflected and emitted from face  26 . The relative volume of light which is emitted from heel  24 , or which is internally reflected and emitted from face  26 , is a function of the critical angle of the material used for prism  16  and the angle of heel  24  in relation to the longitudinal axis of shank  18 . 
         [0031]    Varying the angle of heel  24  in relation to the longitudinal axis of shank  18  will cause more or less light to be directed in front of or behind mirror head  14 , depending on the critical angle of the light conductive material utilized. Moreover, by varying the angle of heel  24  in relation to the longitudinal axis of shank  18 , more or less light may be provided in front of mirror head  14  and a suitable mirror element  10  can be designed for specific needs. 
         [0032]    Alternately, base  22  may be molded having a concave surface such that base  22  can be intimately mated with the curved surface of light source  32 ,  34 ,  36 . Any or all surfaces of the prism including base  22 , heel  24  and face  26  may be provided with a roughened or frosted surface thereby causing light applied to said prism to scatter creating a more uniform illumination pattern and eliminating halos. 
         [0033]    Triangular supports  40  are provided between mirror head  14  and face  26  as shown in  FIGS. 1 and 2  to increase the structural strength of the mirror element. 
         [0034]    The hollow cylindrical shank  18 , disclosed herein and shown in cross section in  FIG. 3 , reduces the volume of plastic material required to manufacture the mirror element  10  as compared with a mirror element having a solid shank. As for example, it is contemplated that the present invention will require fifty percent less plastic material as compared with the mirror element disclosed in U.S. Pat. No. 5,139,421 to Verderber. Reducing the volume of plastic required to manufacture optical mirror element  10  significantly reduces the cost of production. 
         [0035]    Further, the hollow cylindrical shank  18  disclosed herein results in a mirror element  10  having relatively thin wall sections throughout. As for example the mirror element disclosed in U.S. Pat. No. 5,139,421 to Verderber has been manufactured having a solid cylindrical shank with an outside diameter of 0.25 inches. The present invention contemplates a hollow cylindrical shank  18 , as shown in  FIG. 3 , having a 0.25 inch outside diameter with a wall thickness of 0.05 inches or less. The present invention, having relatively thin wall sections throughout, can be molded with faster molding cycles than the mirror element disclosed in U.S. Pat. No. 5,139,421 to Verderber, without resulting gas bubble inclusions, thereby significantly reducing the manufacturing cost. 
         [0036]    Still further, the hollow cylindrical mirror element  10  shank  18  disclosed herein, wherein light source  32 ,  34 ,  36  is contained in close proximity to the mirror head  14 , eliminates light transmission losses through said shank  18 , thereby increasing the efficiency of the instrument. Micro-bubbles and other inclusions are inevitably present within an injection molded part, and as these inclusions decrease the efficiency of light transmission by means of scatter, the optical efficiency of an injection molded optical mirror element is directly related to the distance light must travel through the plastic material. As for example, the mirror element disclosed in U.S. Pat. No. 5,457,611 to Verderber has been manufactured having a shank length of about 1.75 inches, where light is transmitted through its entire length. The present invention contemplates a mirror element  10  where light would be transmitted through prism  16  having a maximum dimension of about 0.25 inches. The present invention therefore contemplates light transmission efficiency losses related to plastic inclusions to be about 0.25 inches divided by 1.75 inches or about one seventh that of the mirror element disclosed in U.S. Pat. No. 5,457,611 to Verderber.