Abstract:
A backlight for an appliance knob provides a light pipe that may receive light from a light source fixed behind a console at a variety of different extensions permitting ready adjustment of the light pipe to fit closely behind the appliance knob with different console thicknesses and tolerances.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a national phase of PCT/US2011/020753, filed Jan. 11, 2011 and claims the benefits of United States Provisional Application Ser. No. 61/297,131 filed Jan. 21, 2010. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to controls for appliances such as ranges and the like and, in particular, to a lighting system for use with such appliance controls. 
     BACKGROUND OF THE INVENTION 
     Appliances, such as gas or electric ranges, may include one or more control knobs presented to the user at a console for adjusting burner heat, oven temperature or the like by operating controls positioned behind the console. Often it is desired to provide illumination of the control knobs, for example, to illuminate printed labels (indicia) indicating the status of the control, for example: low, high, medium, etc. 
     One method of providing this illumination is through the use of an electrical lamp, such as an LED or neon or incandescent bulb, positioned behind the console and providing light to a light pipe that may extend through the hole in the console to provide illumination near the control knob. Desirably, the electrical lamp is mounted to the rear surface of the console of the appliance to provide mechanical support for its associated wiring harness. 
     When a light pipe system must be used with different consoles having different thicknesses (for example sheet-metal versus glass) a light pipe fixed with respect to the front of the console experiences different separations from the electrical lamp fixed with respect to the rear of the console. This slight change in separation between these optical components can substantially change the light output of the light pipe. 
     SUMMARY OF THE INVENTION 
     The present invention provides an illumination system that allows an electrical lamp, or set of lamps such as LEDs, to be fixed with respect to a rear of the console, and the light pipe to be adjusted against the front of the console for different console thicknesses by sliding the light pipe with respect to the lamps. In one embodiment, variations in light output over this range of positioning are reduced by directing light from the electrical lamps not from the end of the light pipe but through the side of an annular light pipe. In this way, the separation distance between the electrical lamps and the light pipe remains substantially constant with different positions of the light pipe appropriate for different console thicknesses. 
     Specifically, the present invention provides an illuminator for an appliance control, the appliance control having a shaft that may extend through an opening in a console to be received by a knob on a front surface of the console. The illuminator includes a light pipe having a first portion adapted to fit beneath the knob on the front surface of the console with a second portion passing through the opening with the shaft and presenting a light receiving surface extending within the console. A housing positionable adjacent to the opening on a rear surface of the console may receive the second portion of the light pipe, the housing holding a plurality of electrical lamps positioned to projecting light into the light receiving surface when the light-receiving surface is so received. The second portion of the light pipe may be slidably adjusted to multiple different positions within the housing to accommodate consoles of different thickness while maintaining a substantially constant separation between the electrical lamps and the light-receiving surface. 
     It is thus a feature of at least one embodiment of the invention to provide a backlight for appliance knobs that may accommodate different thicknesses of consoles and thickness tolerances. 
     The first portion of the light pipe may provide a clamping surface abutting the front surface of the console and the second portion of the light pipe and the housing may have mutually engaging teeth permitting a clamping of the console between the clamping surface of the first portion and a front surface of the housing. 
     It is thus a feature of at least one embodiment of the invention to provide a self-supporting illuminator that can preserve close optical coupling between its halves. 
     The front surface of the housing includes a resilient pad compressible during clamping. 
     It is thus a feature of at least one embodiment of the invention to provide an illuminator with reduced slippage as provided by the contact of the compressible pad with the console surface to provide a more consistent clamping pressure and frictional resistance to torque. 
     The mutually engaging teeth may be threads. 
     It is thus a feature of at least one embodiment of the invention to provide a clamping action that may be readily controlled by torsion on the light pipe from the front of the console. 
     Alternatively, the mutually engaging teeth may be ratchet teeth and a pawl. 
     It is thus a feature of at least one embodiment of the invention provide a rapid assembly method when both sides of the console are readily accessible. 
     The light pipe may have a circular periphery encircling a central bore through which the shaft may pass. 
     It is thus a feature of at least one embodiment of the invention to provide a uniform illumination about a control knob to provide an improved visibility of printed indicia and the outline of the knob. 
     The disk may be less than or equal to the diameter of an outer periphery of the knob. 
     It is thus a feature of at least one embodiment of the invention to provide a backlight defining the periphery of the knob and closely spaced indicia. 
     The first portion of the light pipe may provide a transparent periphery and upper surface permitting light to pass therethrough. 
     It is thus a feature of at least one embodiment of the invention to provide a backlight that may also illuminate a translucent knob material. 
     The second portion of the light pipe may be a tube fitting about the shaft. 
     It is thus a feature of at least one embodiment of the invention to provide a light-receiving surface that may be translated and rotated while maintaining constant angle and separation with fixed lights. 
     The second portion of the light pipe may provide an opaque coating opposite the light-receiving surface. 
     It is thus a feature of at least one embodiment of the invention to provide improved light transmission efficiency for the light pipe. 
     The electrical lamps are light emitting diodes. 
     It is thus a feature of at least one embodiment of the invention to provide an illumination system that may be used with a low illumination level provided by current LEDs. 
     The light emitting diodes may be of two colors wired for separate control. 
     It is thus a feature of at least one embodiment of the invention to permit a change in color of the backlighting to signal burner activity or the like. 
     The electrical lamps may be supported on a planar printed circuit board fitting within the housing about an aperture receiving the second portion of the light pipe, and the electrical lamps may be positioned on the printed circuit board to direct light inward radially toward a center of the aperture. 
     It is thus a feature of at least one embodiment of the invention to provide a simple method of positioning multiple LEDs for uniform illumination of a light pipe. 
     Alternatively, the printed circuit board may be a flexible printed circuit board fitting within the housing about an aperture receiving the second portion of the light pipe, and the electrical lamps may be LEDs mounted on a surface of the printed circuit board and the printed circuit board may be formed into a ring about the aperture so that the LEDs faced inward toward the second portion of the light pipe. 
     It is thus a feature of at least one embodiment of the invention to provide a simple method of fabricating a ring of LEDs. 
     The light pipe may provide a central aperture for receiving the shaft and at least one second aperture for providing air inflow through the console. 
     It is thus a feature of at least one embodiment of the invention to ensure sufficient airflow if the invention is used with a mixing gas valve. 
     The second aperture may be within a tube forming the second portion of the light pipe. 
     It is thus a feature of at least one embodiment of the invention to provide both for the passage of air and light through a constrained opening. 
     The electrical lamps may be mounted adjacent to a reflective surface directing light toward the second portion of the light pipe. 
     Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of the illumination system of the present invention providing a housing mounted to the rear of the console and receiving an annular light pipe inserted into the housing from a front side of the console, the annular light pipe fitting around a gas valve or the like to provide backlighting to a knob controlling the gas valve; 
         FIG. 2  is a cross-section along line  2 - 2  of  FIG. 1  showing engagement between the annular light pipe and housing for a first console thickness as controlled by helical threads; 
         FIG. 3  is a figure similar to that of  FIG. 2  showing engagement between the annular light pipe and the housing for a second console thickness; 
         FIG. 4  is a perspective view of a first embodiment of the invention for supporting electrical lamps for illuminating the light pipe on a planar printed circuit board; 
         FIG. 5  is a fragmentary top planar cross-section of portions of the housing about the electrical lamps of  FIG. 4  providing for directing reflectors; 
         FIG. 6  is a front elevational view of two illumination systems of the present invention as wired to each other in a daisy chain fashion and wired individually to a central controller; 
         FIG. 7  is a figure similar to that of  FIG. 4  showing an alternative embodiment for supporting the electrical lamps on a flexible printed circuit board; and 
         FIG. 8  is a figure similar to that of  FIGS. 2 and 3  showing the electrical lamp supporting system of  FIG. 7  and the use of ratchet teeth instead of threads to assemble the annular light pipe and housing. 
     
    
    
     Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to  FIG. 1 , a control  10  for an appliance or the like may provide, for example, a gas valve  12  having a shaft  14  extending along axis  15  through an opening  16  in a console  18  of the appliance. Lighting circuitry housing  20  may be positioned at the rear of the console  18  and, in one embodiment, may be connected with connecting conductors  21  or the like to an electrical source or other similar housing  20  and central controller (not shown). The lighting circuitry housing  20  may further provide for an opening  22  through which the shaft  14  may extend as it passes through the console  18 . 
     An annular light pipe  24  having a generally cylindrical tubular portion  26  terminates in a radially outwardly extending lip  28 . The annular light pipe  24  may be positioned on the outside of the console  18  with a rear surface of the lip  28  abutting a front surface of the console  18  and the tubular portion  26  may fit through the opening  16  in the console  18  to be received within the opening  22  in the lighting circuitry housing  20 . A series of electrical lamps  29 , for example surface mount light emitting diodes (LEDs), may face radially inward and around the opening  22  within the lighting circuitry housing  20  to project light into the tubular portion  26  to be conducted upward to the lip  28 . 
     A control knob  30  may fit over the lip  28  and may have a socket  32  receiving the shaft  14  to allow manipulation of the latter by the operator grasping the knob  30  and rotating it about the axis  15 . In one embodiment, the radially outwardly extending lip  28  may be circular in periphery and have a diameter approximately equal to or less than a diameter of the knob  30  so as to fit wholly behind the knob  30 . 
     Referring now to  FIG. 2 , lip  28  may be constructed of a transparent or tinted thermoplastic providing a light spreader  38  that will project light radially outward and axially outward toward the user. The light spreader  38  is optically coupled with a corresponding transparent cylindrical annulus  40  extending down along the outside of the tubular portion  26  to be exposed along its outer surface for the receipt of light. The tubular portion  26  may further include an opaque and/or reflective inner wall  42  that extends within and below the transparent cylindrical annulus  40  to provide a series of outwardly facing teeth  44 , implementing in the embodiment shown as helical threads engaging the corresponding mating threads on the lighting circuitry housing  20 . The light pipe  24  may move axially with respect to the lighting circuitry housing  20  to position the lip  28  tightly against the outer surface of the console  18  by rotation of the light pipe  24 . This axial motion compresses the console  18  between the lower surface of the lip  28  and a compression stop  47  on the upper surface of the lighting circuitry housing  20  holding the housing  20  and light pipe  24  tightly in position. In this position, LEDs  29  on a printed circuit board  46  within the lighting circuitry housing  20  and facing radially inward around the opening  22  may project light into a first portion  48  of the transparent cylindrical annulus  40  where the light is conducted by internal reflection upward and outward as indicated generally by arrow  50 . 
     Referring also to  FIG. 5 , the housing  20  provides a pocket  41  about the LED  29  that may provide for a reflective inner surface to help direct light toward the cylindrical annulus  40 . 
     Referring now to  FIG. 3 , for a different console  18 ′ having a greater thickness than console  18 , the light pipe  24  may be moved away from the lighting circuitry housing  20  to accommodate the greater thickness of console  18 ′ so that the LEDs  29  project light into a second portion  52  of the transparent cylindrical annulus  40  providing similar light output as indicated by arrow  50 . The second portion  52  may be axially or rotationally displaced with respect to the first portion  48  without changing the separation between the outer surface of the transparent cylindrical annulus  40  and the LEDs  29  thus providing improved light consistency and optical coupling when the light pipe  24  is so moved. 
     The radial thickness of the transparent cylindrical annulus  40  may be quite thin compared to the area of light projection of the LED  29  enhancing internal reflection within the transparent cylindrical annulus  40  and allowing reduced obstruction of the opening  16  by the light pipe  24  as promotes air influx in a gas valve design as will be described below. In one embodiment, console thicknesses may vary between 1 mm and 4 mm and yet still be accommodated in this manner. 
     Referring now to  FIGS. 2 and 4 , as noted above, the LEDs  29  may be mounted on a planar printed circuit board  46  arranged about an aperture  51  that may accept the cylindrical annulus  40 . The LEDs  29  may be oriented to emit light parallel to the surface of the printed circuit board on which they are mounted. Printed circuit board  46  may also support other circuitry interconnected by conductive traces and may provide for connection to the conductors  21  (shown in  FIGS. 1 and 6 ). In one embodiment, every other LED  29  may be a different color from its neighbors (for example alternating white and amber LEDs) and the LEDs  29  may be connected so that the different colors may be independently illuminated. 
     Referring now to  FIG. 6 , multiple controls  10 ,  10 ′ may receive a common power line  21   a  being one of the conductors  21  and may provide individually for various control lines  21   b ,  21   c  providing control, for example, of the color of the LEDs  29  being illuminated. These control lines  21   b ,  21   c  may connect with a controller  53  that may also receive signals from a switch (not shown) associated with the gas valve  12  so that the colors of the LEDs  29  may be adjusted to indicate whether the valve  12  is open or closed (and/or possibly the degree of opening of the valve  12 ) to provide a visual indication to the consumer of which burners are active. The controller  53  may include a processor  55  executing a stored program  56  for this purpose, as is understood in the art. 
     Referring still to  FIG. 6  and also to  FIG. 1 , the lip  28  of the light pipe  24  may provide for a central bore  58  fitting around a sleeve  60  surrounding the shaft  14  on the valve  12  to accurately position the lip  28  concentrically about the shaft  14 . Opposed, arcuate air vent apertures  62  may surround the bore  58  to provide for intake of air necessary for the operation and air mixing element of the gas valve  12 . These apertures  62  may in turn be surrounded by a ring  64  providing the outer circular periphery to the lip  28  and, on a lower surface, an attachment circle for the upper end of the transparent cylindrical annulus  40 . 
     Referring now to  FIG. 7 , in an alternative embodiment, the LEDs  29  may emit light perpendicularly to the surface of the printed circuit  46 ′ and the printed circuit board  46 ′ may be a flexible printed circuit board rolled to form a semi-cylinder around the outside of the transparent cylindrical annulus  40 . The flexible printed circuit board  46 ′ may be connected directly to a connector block  65  providing an alternative electrical connection means. In both the embodiments of  FIG. 4  and  FIG. 7 , the printed circuit board may be coated with a reflective material to improve the direction of light to the cylindrical annulus  40 . 
     Referring now to  FIG. 8 , in an alternative embodiment, the housing  20  may provide for a downwardly extending ratchet pawl  70  that may in turn engage with corresponding ratchet teeth  72  so that the light pipe  24  may be pressed downward toward the housing  20  without rotation and locked in that downward position by engaging ratchet teeth  72  and pawl  70 . 
     Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context. 
     When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of such elements or features. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
     References to “a controller” and “a processor” can be understood to include one or more controllers or processors that can communicate in a stand-alone and/or a distributed environment(s), and can thus be configured to communicate via wired or wireless communications with other processors, where such one or more processor can be configured to operate on one or more processor-controlled devices that can be similar or different devices. Furthermore, references to memory, unless otherwise specified, can include one or more processor-readable and accessible memory elements and/or components that can be internal to the processor-controlled device, external to the processor-controlled device, and can be accessed via a wired or wireless network. 
     It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein and the claims should be understood to include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. All of the publications described herein, including patents and non-patent publications, are hereby incorporated herein by reference in their entireties. 
     Various features of the invention are set forth in the following claims. It should be understood that the invention is not limited in its application to the details of construction and arrangements of the components set forth herein. The invention is capable of other embodiments and of being practiced or carried out in various ways. Variations and modifications of the foregoing are within the scope of the present invention. It also being understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention.