Abstract:
A shaft of a rotary switch, for example, useful as a control for an appliance, such as a washing machine, incorporates an LED at the end of the shaft and projecting light laterally from the shaft to provide an indication of the rotary position of the corresponding knob with respect to printed indicia on a console. The LED may be powered by slip rings incorporated into the rotary switch and communicating directly with line power as controlled by the limiting resistor and the shaft may include a controlled breakage feature providing LED conductors that are recessed within the shaft in the event of shaft breakage to reduce the chance of operator contact with line voltage.

Description:
CROSS-REFERENCED TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 61/145634 filed on Jan. 19, 2009 and hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    It is known to provide controls for common household appliances that provide an illuminated indication of their setting, for example, using LEDs, backlit LCDs, or plasma type displays. Such illuminated controls are aesthetically attractive, allow the appliance to be easily used in low light areas, and provide an indication of their setting visible at a distance. 
         [0003]    Present electrical and electromechanical controls for washing machines and the like provide an operator knob having a pointer, for example an embossed line or arrow, that may be rotated into alignment with preprinted indicia indicating the control&#39;s setting. Often the indicia are printed on an opaque, enameled metal sheet. A rotational control of this type is both familiar and provides an intuitive representation of the various machine cycles, both during setting of the machine and during its execution of cycle stages when the knob may rotate as each stage is completed. Nevertheless, operation of this type of rotation control in lowlight settings can be difficult. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention provides a simple and energy efficient method of providing setting illumination when using standard electromechanical or electrical rotating knob controls such as found in a washing machine. In one embodiment of the invention, a light emitting diode is placed into the end of an operator shaft receiving the control knob. Sliding contacts provide power to the LED from within the housing. By moving the LED closer to the knob and allowing it to be preferentially aligned with the pointer on the knob, substantially improved light-efficiency can be obtained with a rotating type control. 
         [0005]    Specifically, the present invention provides a control for an appliance or the like having an electrical switch with contacts for controlling the appliance. A shaft communicates at a proximal end with the electrical switch and actuates the electrical switch with rotation of the shaft about an axis. The shaft has a light passageway at a distal end, and an LED positioned within the shaft at the distal end is aligned with the light passageway to project a beam of light substantially perpendicular to the axis therefrom. 
         [0006]    It is thus a feature of at least one embodiment of the invention to provide improved illumination of the positioning of a rotary operator of an electric switch by permitting a more direct illumination path from a distally located LED. 
         [0007]    The control may further include second contacts communicating with the LED to conduct electricity to the LED with rotation of the shaft. 
         [0008]    It is thus a feature of at least one embodiment of the invention to provide improved illumination in a free rotating control. 
         [0009]    The electrical switch may include terminals receiving line voltage and the second contacts may communicate with corresponding contacts connected to the line voltage. 
         [0010]    It is thus a feature of at least one embodiment of the invention to provide a control suitable for use in standard appliances operating at 110-120 VAC. 
         [0011]    The control may include at least one electrical resistor providing a voltage dropping of the line voltage to control the current passing through the LED. 
         [0012]    It is thus a feature of at least one embodiment of the invention to provide simple, integrated power conditioning for powering the LED suitable for an appliance control. 
         [0013]    The LED may communicate with the second contacts by means of electrical conductors preferentially separating into distal and proximal portions at a separation plane crossing the axis and displaced with respect to a fracture plane of the shaft so that in the event of fracturing of the shaft the distal portion remains recessed within the shaft beneath the fracture plane. 
         [0014]    It is thus a feature of at least one embodiment of the invention to permit direct connection of the LED to line voltage while reducing the chance that the user will be exposed to line voltage directly in the event of damage of the control. 
         [0015]    The distal and proximal portions of the electrical conductors may be joined by a pin and socket at the separation plane. 
         [0016]    It is thus a feature of at least one embodiment of the invention to provide a simple mechanism for controlling a point of separation of the electrical conductors. 
         [0017]    Alternatively, the distal and proximal portions of the electrical conductors may be joined by a spring and abutting contact at the separation plane. The spring may communicate between the abutting contact portion and a trace on a printed circuit board providing a contact carrier. 
         [0018]    It is thus a feature of at least one embodiment of the invention to provide a controlled separation of the conductors and a simple method of communicating between the LED and a printed circuit board supporting rotating electrical contacts. 
         [0019]    The fracture plane of the shaft may be defined by a stress-concentrating feature in the shaft. 
         [0020]    It is thus a feature of at least one embodiment of the invention to control a fracture point of the shaft to better shield the user from possibly hazardous voltages. 
         [0021]    The control may further include a knob engaging the distal end of the shaft in the knob and having a second light passageway aligned with the light passageway of the distal end of the shaft to communicate light from the LED to an edge of the knob to illuminate indicia indicating cycle information. 
         [0022]    It is thus a feature of at least one embodiment of the invention to provide a control that may work with a variety of different interchangeable knobs for different appliance models. 
         [0023]    The second light passageway may be a lens. 
         [0024]    It is thus a feature of at least one embodiment of the invention to permit further diffusion, focusing or collimation of the light from the LED by the knob such as may be changed by different knobs for different applications. 
         [0025]    The second light passageway of the knob may light at the panel holding the indicia. 
         [0026]    It is thus a feature of at least one embodiment of the invention to permit a direction of the light by the knob to focus the light on printed indicia on the panel. 
         [0027]    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 
         [0028]      FIG. 1  is a perspective view of a washing machine showing an enlarged detail of a control knob providing illumination of its environment; 
           [0029]      FIG. 2  is an exploded perspective view of a control shaft and contact system, the control shaft receiving the control knob of  FIG. 1  and having an incorporated LED; 
           [0030]      FIG. 3  is a fragmentary cross-section along line  3 - 3  of  FIG. 1  showing alignment of the LED in the operator shaft with a lens in the control knob; 
           [0031]      FIG. 4  is a fragmentary cross-section of the operator shaft and control knob taken along line  4 - 4  of  FIG. 1 ; 
           [0032]      FIG. 5  is an elevation of cross-section taken along lines  5 - 5  of  FIG. 2  showing the joining of internal conductors of the intact shaft by pin and socket connectors defining a separation plane; 
           [0033]      FIG. 6  is a figure similar to that of  FIG. 5  showing disconnection of the pin and socket connector when the shaft is broken at a fracture plane; 
           [0034]      FIG. 7  is a cross-sectional view similar to that of  FIG. 5  of an alternative embodiment to the pin and socket connectors of  FIGS. 5 and 6  employing contact and spring connectors that provide for separation of the internal conductors of the shaft as well as connection of the LED to a printed circuit board providing a support disk for contacts of the switch; and 
           [0035]      FIG. 8  is a fragmentary figure of the control shaft having the LED displaced below a fracture plane and using a light pipe to conduct light out of the control shaft 
       
    
    
       [0036]    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 INVENTION 
       [0037]    Referring now to  FIG. 1 , a washing machine  10  suitable for use with the present invention includes a housing  12 , typically of enameled steel, having a front facing console  14  supporting a control  16  such as a cycle timer or the like. The washing machine  10  may include an internal spin basket, motor, and water-handling electromechanical valves (not shown) as understood in the art. 
         [0038]    A control  16 , for example a cycle timer, attaches in part behind the console  14  and provides a shaft  34  (not shown in  FIG. 1 ) which passes through the console  14  and attaches to a knob  18 , the latter which may be rotated to control the cycling of the washing machine  10  and which may also rotate during operation to indicate a current cycle stage. 
         [0039]    The knob  18  may include a finger grip  20  that may be grasped by a user to rotate the knob  18  about a center axis  22 . A transparent or translucent lens  23  may be exposed at one end of the finger grip  20  and may be internally illuminated (as will be described) both to provide a visual indication of the pointer-end of the knob  18  and to provide an illuminating beam  24  striking printed indicia  26  printed on the face of the console  14 , for example, such as describe the current washing cycle or, when used in other control applications, describe water temperature or the like. 
         [0040]    Referring now to  FIG. 2 , the control  16  includes a housing  30  sitting behind the console  14  and holding contacts  17  of the control  16 . In one embodiment, the contacts  17  may include a set of cantilevered flexible metallic fingers  19  contacting, at the cantilevered end, the under surface of a disk-shaped contact carrier  32  having conductive traces  21  formed thereon, the latter which interconnect with the fingers  19  as the contact carrier  32  is rotated about axis  22 . The contact carrier  32  may, for example, be a disc of printed circuit board material having conductive traces  21  formed using standard etching techniques. 
         [0041]    At least some of the metallic fingers  19  may connect with a motor, solenoid, or other actuator (not shown) of the washing machine  10  to control the application of line voltage (approximately 115 VAC) to those components to control the same directly or may connect with a microprocessor (not shown) providing similar signals indicating rotation of the contact carrier  32 . Optionally, a motor or the like (not shown) may advance the contact carrier  32  during operation of the washing machine  10  in a conventional matter. 
         [0042]    More generally, the contact carrier  32  may be rotated manually through the shaft  34  connected to the knob  18 . The shaft  34  may have a cylindrical portion  36  extending from a proximal end attached to the contact carrier  32 , out of the housing  30  to pass through the console  14  and to be received by the knob  18 . The cylindrical portion  36  within the console  14  may further attach to, for example, a gear  40  concentric with the operator shaft  34  (shown in fragment) providing a detent surface interengaging with a spring finger (not shown) providing incremental stable positions of rotation of the shaft  34  corresponding to switch states of the contacts  17 . 
         [0043]    In one embodiment, the operator shaft  34  may be molded entirely or in part of a transparent or translucent thermoplastic material. Molded or inserted within the distal end of the cylindrical portion  36  of the operator shaft  34  is a light emitting diode  42  positioned to project a light beam  44  generally perpendicular to the axis  22 . Alternatively, as shown, in  FIG. 3 , the LED  42  may be aligned with an opening  59  allowing the light to pass out of this opening  59  without attenuation by plastic material. 
         [0044]    The LED  42  may be attached to a lead frame consisting of axial conductors  46  that may pass axially along the axis  22  within the cylindrical portion  36  toward the contact carrier  32  and then bend perpendicularly to the axis  22  to extend along the upper side of the rotational contact carrier  32  to connect with the traces  21  on the lower side of the contact carrier  32  through vias  39 . Alternatively, the conductors  46  may be part of a narrow printed circuit board molded to fit into the shaft  34 . 
         [0045]    Two of the traces  21  on the underside of the contact carrier  32  may be continuous rings concentric about axis  22  and connected through metallic fingers  19 , respectively, to a source of line power  52  and ground  54 , in series with a current-limiting resistor  56  to provide power to the LED over a range of different rotations of the shaft  34  about axis  22 . The traces  48  may alternatively or in addition provide for shunted breaks (not shown) so that at certain rotative positions of the contact carrier  32 , the LED  42  is not illuminated. 
         [0046]    The other traces  21  provide switching functions to control the washing machine  10  and may be continuous or interrupted and interconnected and/or connected alternately to one of power  52  or ground  54  by traces on the upper surface of the contact carrier  32 . In this way, power or ground may be applied through selective terminals  25  or those terminals  25  may be shorted together or isolated from each other with rotation of the contact carrier  32 . 
         [0047]    Referring now to  FIG. 3 , the LED  42  may face a flattened portion  58  on the cylindrical portion  36  to allow light from the LED to pass out of the cylindrical portion  36  with a minimum of internal reflection through opening  59 . This flattened portion  58  may further provide a keying controlling the orientation of the knob  18  on the shaft so that the light handling features of the knob  18  are properly aligned with the LED  42 . 
         [0048]    Specifically, and referring also to  FIG. 4 , this light passing out of the cylindrical portion  36  may be received by a corresponding lens  23  within the knob  18 . The lens  60  may serve to provide a beam spreading function or a collimation function for the beam and/or may direct the beam downward toward the indicia  26  on the console  14  surrounding the knob  18 . 
         [0049]    By moving the LED  42  toward a distal end  61  of the shaft  34 , a smaller LED may produce a higher intensity beam exiting the knob  18 . 
         [0050]    Referring now to  FIG. 5 , as noted, the LED  42  connects directly to line voltage through resistor  56  and therefore, in certain cases of resistor failure and damage of the shaft  34 , may expose a user to a live electrical conductor. Accordingly the conductors  46  may be separated into distal conductors  46   a  and proximal conductors  46   b  separated from each other along axis  22  by interengaging pins  62  attached to distal conductors  46   a  and sockets  64  attached to proximal conductors  46   b.  These pins  62  and sockets  64  may be molded into the thermoplastic of the shaft  34  at a feature  66 , for example, a notch in the shaft  34  passing circumferentially about the shaft  34  to promote fracture of the shaft  34 , in the event of impact, at the feature  66 . In this case, the feature  66  defines a fracture plane  67  generally perpendicular to the axis  22 . 
         [0051]    Referring now to  FIG. 6 , upon fracture at the fracture plane  67 , the pins  62  disengage from the sockets  64  at a separation plane  68  so that the sockets  64  remain recessed beneath thermoplastic of the remaining shaft  34  thus removed from accidental contact to the customer. The fracture plane  67  may be alternatively defined by internally weakened structure of the shaft  34  and/or a location near the hole through the console  14 , the edge of which may act as a fulcrum against which the shaft  34  will likely break in the event of a side impact. 
         [0052]    Alternatively, as shown in  FIG. 7 , the distal conductors  46   a  may join with the proximal conductors  46   b  at the separation plane  68  at an interface formed between conductor  46   a  and a blunt contact  70  terminating a helical compression spring  72 , the latter two forming the entirety of the proximal conductors  46   b.  When the shaft  34  is intact, as depicted, a slight compression of the helical compression springs  72  holds the contacts  70  against the ends of conductors  46   a  which may terminate the ends of the distal conductors  46   a.  This compression, however, once released upon breakage of the shaft  34 , is insufficient to expose the springs of conductors  46   b  to the user. 
         [0053]    Referring now to  FIG. 8 , in an alternative embodiment, the LED  42  may be positioned to face upward with in the shaft  34  to direct light into an axial portion  70  of a light pipe  72 . Light pipe  72  may, for example, be a transparent thermoplastic rod conducting light by internal reflection in the manner of a fiber optic. Light conducted from the axial portion  70  may then be directed perpendicular to the axis  22  by a radial portion  74  forming a continuation of the same light pipe  72 . Because the LED  42  is embedded in the shaft  34 , alignment of the LED  42  with the light pipe  72  is insured for all rotary positions. 
         [0054]    Variations and modifications of the foregoing are within the scope of the present invention. It is 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. The claims are to be construed to include alternative embodiments to the extent permitted by the prior art. 
         [0055]    Various features of the invention are set forth in the following claims.