Abstract:
A composite knob including an injection molded translucent core having a side wall and a top wall with light pipe window or a light pipe opening formed in these walls. A trim ring is positioned on the core and has an opening therethrough to align with the light pipe window or opening. A cover is mounted on the trim ring and core and includes an opening aligned with the trim ring opening and the light pipe window or opening. A light pipe located in the light pipe window or light pipe opening is visible through the trim ring and cover openings. An opaque plastic light transmitting barrier is formed between the light pipe window or light pipe and the openings in the trim ring and cover. The light transmitting barrier is molded as a part of a gripping overlay applied to the outer surface of the skirt of the knob.

Description:
This application is a continuation of U.S. patent application, Ser. No. 10/808,069, filed Mar. 24, 2004 now U.S. Pat. No. 7,036,188, which prior application is incorporated in its entirety into this application by reference for all purposes. 

   BACKGROUND AND SUMMARY OF THE INVENTION 
   This invention is directed to a light leakage barrier for a back lighted indicator of a control knob or button. The conventional back lighted indicator, or light pipe as it is commonly called, is flush with or projects beyond the surface of the core of the conventional injection molded control knob or button in which it is mounted either through an opening in the core wall or in a window housing such as a fin which is formed integrally with and projects beyond the core wall. The exposed sides of the back lighted indicator or the side walls of its fin, which are not intended to transmit light to a viewer, are obscured by an opaque outer plastic covering. This molded, opaque outer covering overlies or abuts the edges of the light pipe indicator or the walls of its fin to provide a sharp cutoff and thus a high clarity definition for the back lighted indicator. When a back lighted indicator is provided in a knob which has a separately formed or assembled cover and/or a decorative trim ring, it has been difficult to prevent light leakage through the gaps which occur where the back lighted indicator projects through an opening in the cover or an opening in the decorative trim ring and this light leakage presents an irregular or ragged indicator to the viewer. 
   Therefore, an object of my invention is a light leakage barrier for the gaps which occur between a decorative trim ring, a cover and a light pipe indicator in a composite knob or button. 
   Another object of my invention is a light leakage barrier for a back lighted indicator which barrier is formed simultaneously with a gripping overlay applied to the skirt of a knob or the outer wall of a button. 
   A further object of my invention is a light barrier which is adaptable to both back lighted indicators which are flush with or project through openings in the core and to such indicators which are located in window housings such as fins which project beyond the outer surfaces of the core. 
   Other objects of the invention will be found in the following specification, claims and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an enlarged, perspective view of a first embodiment of a composite knob incorporating the novel aspects of the invention; 
       FIG. 2  is a top plan view of the knob of  FIG. 1 ; 
       FIG. 3  is a side elevational view of the knob of  FIG. 1 ; 
       FIG. 4  is a bottom plan view of the knob of  FIG. 1 ; 
       FIG. 5  is an enlarged, cross-sectional view taken along line  5 — 5  of  FIG. 2 ; 
       FIG. 6  is an enlarged, cross-sectional view taken along line  6 — 6  of  FIG. 2 ; 
       FIG. 7  is an exploded view of the knob of  FIG. 1 ; 
       FIG. 8  is an exploded view of a second embodiment of a knob of this invention; and 
       FIG. 9  is an exploded view of a third embodiment of a knob of this invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 through 7  of the drawings show a first embodiment of the invention in a composite knob or button  11 . The knob includes a core  13  having integral skirt  15  and an end or top wall  17 , a hub  19  extending from the top or end wall  17  and a socket  21  formed in the hub with gripping fingers  23  formed in the socket. The top or end wall  17  is formed with a sloping annular peripheral shoulder  25 . The core may be molded of a white plastic such as an acetyl which is translucent, at least in thin layers. 
   A fin  31  is formed in the skirt  15  and end wall  17  of the core  13 . The fin includes a rectangular web  33  which is supported by side Walls  35  and an end wall  37 . The web  33  is referred to as a window because in back lighted knobs, the core  13  is formed of a plastic that is translucent, at least in the thicknesses used for knobs and buttons, and the web is formed usually having a thickness less than that of the front wall  17  of the core and sufficiently thin to allow the passage of light. 
   A circular disk or trim ring  45  is formed of metal or a plated plastic and includes an end wall  47  and a rim  49  with an inclined wall  51  connecting the rim to the end wall. The rim  49  and inclined wall  51  may be provided with a decorative appearance or finish. A central opening  53  is formed in the end wall  47 . A plurality of spaced holes  55  are formed in the disk. A radially extending passage  57  that connects the central opening  53  with the rim  49  of the end wall is also formed in the disk  45 . 
   A domed cover  61  includes a down turned peripheral wall  63  and a centrally located tubular mount  65 . The cover also includes mounting pins  67  which align with the holes  55  in the circular disk or trim ring  45 . A radially extending passage  69  dimensioned to receive the fin  31  of the core  13  and a light barrier to be hereinafter described is formed in the cover. The cover  61  is aligned with the holes  55  in the trim ring  45  and the fin  31  and press fitted into engagement with the ring and core. 
   A light transmitting indicator  75 , also referred to as a light pipe, is formed as a flat, irregularly shaped piece of plastic such as a polycarbonate. The light pipe includes an irregular edge  77  which engages the web  33  of the fin  31 . The light pipe  75  also has side walls  79  which engage the interiors of the side walls  35  of the fin when the light pipe is inserted in the fin or the fin and core are molded over the light pipe. 
   An opaque outer skirt and core covering  85  is formed of an injection molded plastic such as black nylon with ribs  87  located on the exterior thereof for gripping purposes. The injection molded plastic of the opaque outer skirt and core covering  85  also forms a light barrier  89  having barrier side walls  91  and  93  ( FIG. 5 ) and an end wall  95  ( FIG. 6 ) which are dimensioned to engage and fit tightly against the side walls  35  and end wall  37  of the fin  31 . The light barrier closes gaps  97  and  99  ( FIG. 1 ), respectively, which exist where the radially extending passage  57  of the trim ring  45  extends through the rim  49  and inclined wall  51  and are located contiguous to the side walls  35  of the fin  31 . The cover  61  terminates radially short of the inclined wall  51  and rim  49  of the trim ring  45  so it provides no concealing effect to these portions of the trim ring. The injection molded plastic forms a covering over the top or end wall  17  of the core which covering connects the opaque outer skirt covering  100  with the barrier side walls  91  and  93  and end wall  95 . The core top wall covering is disk shaped with an annular groove  101  formed near the periphery of the disk and an annular ridge  103  located inwardly of the groove with the ridge surrounding a central circular depression  105  in the disk. The rim  49  of the trim ring  45  seats in the annular groove  101  to mount the trim ring on the core  13 . The skirt and core covering  85 , light barrier  89  and end wall covering  100  are formed in a single shot of opaque plastic. 
   A second embodiment of a knob or button incorporating the novel aspects of the invention is shown in exploded view in  FIG. 8  of the drawings. This modified knob or button  111  includes a core  113  having an integral skirt  115  and an end or top wall  117 . A hub (not shown) extends from the underside of the top or end wall  117  and a socket (not shown) is formed in the hub with gripping fingers (not shown) formed in the socket essentially as shown in  FIG. 6  of the drawings of the first embodiment of the invention. The top or end wall  117  is formed with a sloping annular peripheral shoulder  125 . A passage  119  extends through the skirt  115  and the end wall  117  of the core  113 . The passage  119  is sufficiently wide to receive a light transmitting indicator, to be hereinafter described, similar to the light transmitting indicator or light pipe  75  described in connection with the first embodiment of this invention. The core may be molded of a white plastic such as an acetyl which is translucent, at least in thin layers. 
   A circular disk or trim ring  145  is formed of metal or a plated plastic and includes an end wall  147  and a rim  149  with an inclined wall  151  connecting the rim to the end wall. The rim  149  and inclined wall  151  may be provided with a decorative appearance or finish. A central opening  153  is formed in the end wall  147 . A plurality of spaced holes  155  are formed in the disk. Additionally, a radially extending passage  157  connects the central opening  153  of the disk with the rim  149  of the end wall. 
   A domed cover  161  includes a downturned peripheral wall  163  and a centrally located tubular mount which is not shown in the drawings but is similar to tubular mount  65 . The cover also includes downwardly extending mounting pins  167  which align with the holes  155  in the circular disk or trim ring  145 . A radially extending passage  169  dimensioned to receive a light transmitting indicator and its barrier walls is formed in the cover  161 . The domed cover terminates radially short of the inclined wall  151  and rim  149  so it provides no concealing effect to these portions of the trim ring. 
   A light transmitting indicator  175 , also referred to as a light pipe, is formed as a flat, irregularly shaped piece of plastic such as a polycarbonate. The light pipe includes an irregular edge  177  which extends into the radially extending passage  169  of the domed cover  161 . The light pipe  175  also has side walls  179  and an end wall  181  that engage the walls of a light transmitting barrier to be hereinafter described which is installed in the passage  119  extending through the core  113 . The edge  177  of the light pipe may be flush with the core  113  or may extend slightly outwardly thereof. 
   An opaque outer skirt and core covering  185  is formed of an injection molded plastic such as black nylon with exterior ribs  187  located on the exterior of the skirt covering for gripping purposes. The injection molded plastic of the opaque outer skirt and core covering  185  also forms a light barrier  189  having barrier side walls  191  and  193  and a barrier end wall  195  which are dimensioned to engage and fit tightly against the side walls  179  and end wall  181  of the light transmitting indicator  175  with the light barrier closing gaps which exist where the rim  149  and inclined wall  151  of the trim ring  145  and the similar passage  169  of the cover  161  are located contiguous to the side walls  179  and end wall  181  of the light transmitting indicator  175 . The injection molded plastic forms a layer  200  over the top or end wall  117  of the core  113  which layer connects the opaque outer skirt layer with the barrier side walls  191  and  193  and end wall  195 . The core top wall covering or layer  200  is disk shaped with an annular groove  201  formed near the periphery of the disk and an annular ridge  203  located inwardly of the groove with the ridge surrounding a central circular depression  205  in the disk. The rim  149  of the trim ring  145  seats in the annular groove  201  to mount the trim ring on the core  113 . The skirt and core covering  185 , light barrier  189  and end wall covering  200  are formed in a single shot of opaque plastic. 
   A third embodiment of a knob or button incorporating the novel aspects of the invention is shown in exploded view in  FIG. 9  of the drawings. This modified knob or button  211  includes a core  213  having an integral skirt  215  and an end or top wall  217 . A hub (not shown) extends from the underside of the top or end wall  217  and a socket (not shown) is formed in the hub with gripping fingers formed in the socket essentially as shown in  FIG. 6  of the drawings of the first embodiment of the invention. The top or end wall  217  is formed with a sloping annular peripheral shoulder  225 . A passage  219  extends through the skirt  215  and the end wall  217  of the core  213 . The passage  219  is sufficiently wide to receive a light transmitting indicator, to be hereinafter described, similar to the light transmitting indicator or light pipe  75  described in connection with the first embodiment of the invention. Exterior ribs  221  are formed on the exterior of the skirt  215  for gripping purposes. 
   The core is molded of an opaque plastic such as black nylon. A light barrier  227  is molded integrally with the core  213 . It includes barrier side walls  229  and  231  and barrier end wall  233  which extend longitudinally outwardly from said end or top wall  217  of the core  213 . The barrier walls  229 ,  231  and  233  form an extension of the passage  219  which extends through the skirt  215  and end wall  217  of the core. The barrier side walls  229  and  231  may extend slightly radially outwardly of the exterior ribs  221  of the skirt  215 . An annular groove  235  is formed near the periphery of the shoulder  225  of the top or end wall  217  of the core  213 . 
   A circular disk or trim ring  245  is formed of metal or plated plastic and includes an end wall  247  and a rim  249  with an inclined wall  251  connecting the rim to the end wall. The rim  249  and the inclined wall  251  may be provided with a decorative appearance or finish. A central opening  253  is formed in the end wall  247 . A plurality of spaced holes  255  are formed in the disk. Additionally, a radially extending passage  257  connects the central opening  253  of the disk with the rim  249  of the end wall. The rim  249  of the trim ring seats in the annular groove  235  to mount the trim ring on the core. 
   A domed cover  261  includes a downturned peripheral wall  263  and a centrally located tubular mount which is not shown in the drawings but is similar to tubular mount  65  of the first embodiment of the invention. The cover also includes downwardly extending mounting pins  267  which align with holes  255  in the circular disk or trim ring  245 . A radially extending passage  269  dimensioned to receive a light transmitting indicator and its barrier walls  229 ,  231  and  233  is formed in the cover  261 . The domed cover terminates radially short of the inclined wall  251  and rim  249  so it provides no concealing effect to these portions of the trim ring  245 . 
   A light transmitting indicator  275 , also referred to as a light pipe, is formed as a flat, irregular shaped piece of plastic such as a polycarbonate. The light pipe includes an irregular edge  277  which extends into the radially extending passage  269  of the domed cover  261 . The light pipe has side walls  279  and an end wall  281  that engage the barrier walls  229 ,  231  and  233  of the light barrier  227 . 
   The composite knobs or buttons of this invention can be manufactured using various techniques such as multi-shot molding, insert molding, or individual molding of the component parts with later assembly. For example, using the multi-shot molding process, the light pipe can be molded in a first shot and then the core can be over molded the light pipe, whether or not a light pipe housing such as a fin is provided, or if the light pipe just extends through a passage in the core as shown in the second embodiment of the invention. The ribbed opaque outer plastic that forms the opaque outer skirt gripping surface, core covering and light barrier can then be molded. In this type of molding technique, the light pipe may function as an anvil, if a fin with a thin window is provided in the core. The metal or plastic plated ring is then snapped into position on the composite knob and a cover is attached over to the core and the ring. 
   In the insert method of molding, the light pipe and core are molded separately and then assembled with the light pipe positioned in the core and supporting a window if one is used to function as an anvil. The outer gripping surface, core covering and light pipe barrier are then over molded with the light pipe functioning as an anvil supporting the window in a fin. A metal or plastic plated ring is placed on the knob made by the previous steps and a cover is then attached over the ring and core. 
   Another method of molding is to mold each element separately and then assemble the elements into a final composite knob or button. As previously mentioned, the ring may be metal or may be plastic that is plated or coated with metallic finishes or otherwise.