Abstract:
A method and apparatus for an appliance control knob incorporating a microprocessor and a status display built into the control knob housing. Such a control knob gives the appliance a clean and uncluttered appearance, and allows a user of the appliance both to control the appliance, for example by adjusting the oven temperature setpoint, and to be informed of the status of the appliance, for example the actual oven temperature, in a way that is easy to understand and to use.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to the field of appliances, and particularly to status displays and operating controls used on appliances.  
         BACKGROUND OF THE INVENTION  
         [0002]    Professional and high end domestic appliances have become increasingly sophisticated in function and appearance in response to evolving consumer tastes and needs.  
           [0003]    Appliances, particularly appliances which include digital control systems, may incorporate complicated status displays and operating controls to support sophisticated functionality. However such displays and controls are often perceived as complicated, non-intuitive, and visually unattractive. It can be difficult to design an appliance that provides the controls and status displays needed to support sophisticated functionality along with a clean, uncluttered appearance.  
           [0004]    Usability and ergonomics also play an important role in consumer purchasing decisions. For example, an appliance design which places a display of actual oven temperature directly adjacent to the knob which controls the oven temperature setpoint may make an appliance easier to operate and understand.  
           [0005]    For these reasons, a method and apparatus including a control knob with a built in status display would appeal to consumers and increase sales of appliances which incorporate the method and apparatus.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention relates to a method and apparatus which includes an appliance control knob incorporating a microprocessor and a status display built into the control knob housing. According to another aspect of the invention, the appliance control knob incorporates a bipolar connector which serves both as an axle for rotation of the control knob, and as an electrical connector for transmission of both data and power to the control knob.  
           [0007]    Such a control knob allows a user of the appliance both to control the appliance, for example by adjusting the oven temperature setpoint, and to be informed of the status of the appliance, for example the actual oven temperature, in a way that is easy to understand and to use. Such a control knob can display appliance status information that would otherwise require a separate display unit, making the appearance of the appliance cleaner and more appealing.  
           [0008]    Such a control knob may be formed as a separate sealed component which plugs into a socket, allowing the control knob to be easily removed and replaced, for example for maintenance, repair, or cleaning of the knob and appliance.  
           [0009]    A appliance control knob according to the invention may include a second control surface, to form a composite control knob assembly. For example, such a composite control knob assembly may provide an outside rotating bezel to set the oven cooking mode (e.g. bake, broil, or convention) with an inner control knob according to the invention used to adjust oven temperature setpoint and display actual oven temperature.  
           [0010]    Further objects, features, and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the following drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    In the drawings:  
         [0012]    [0012]FIG. 1 is a perspective view of an appliance incorporating a preferred embodiment of a composite control knob assembly according to the invention.  
         [0013]    [0013]FIG. 2 is an exploded view of a preferred embodiment of a composite control knob assembly according to the invention.  
         [0014]    [0014]FIG. 3 is a perspective view of a preferred embodiment of a control knob according to the invention.  
         [0015]    [0015]FIG. 4 is a side view of a preferred embodiment of a control knob according to the invention.  
         [0016]    [0016]FIG. 5 is a front view of a preferred embodiment of a control knob according to the invention.  
         [0017]    [0017]FIG. 6 is a top view of a preferred embodiment of a control knob according to the invention.  
         [0018]    [0018]FIG. 7 is a perspective view of a preferred embodiment of a control knob and second control surface according to the invention.  
         [0019]    [0019]FIG. 8 is a perspective view of a preferred embodiment of a second control surface according to the invention.  
         [0020]    [0020]FIG. 9 is a side view of a preferred embodiment of a second control surface according to the invention.  
         [0021]    [0021]FIG. 10 is a front view of a preferred embodiment of a second control surface according to the invention.  
         [0022]    [0022]FIG. 11 is a top view of a preferred embodiment of a second control surface according to the invention.  
         [0023]    [0023]FIG. 12 is a rear view of a preferred embodiment of a second control surface according to the invention.  
         [0024]    [0024]FIG. 13 is a perspective view of a preferred embodiment of a socket according to the invention.  
         [0025]    [0025]FIG. 14 is an exploded view of a preferred embodiment of a socket and a second control surface according to the invention.  
         [0026]    [0026]FIG. 15 is a block diagram of an electronic circuit for use in a preferred embodiment of a control knob according to the invention.  
         [0027]    [0027]FIG. 16 is a layout for a circuit board for use in a preferred embodiment of a control knob according to the invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]    With reference to the drawings, the lower left portion of FIG. 1 shows a perspective view of an appliance, indicated generally at  20 . The upper portion of FIG. 1 shows a close-up view of the controls for the appliance, including a preferred embodiment of a composite control knob assembly according to the invention indicated generally at  21 , comprised of a control knob according to the invention indicated generally at  27  and an optional second control surface indicated generally at  25 .  
         [0029]    As shown in the exploded FIG. 2, a preferred embodiment of a control knob according to the invention, indicated generally at  27 , may include a knob housing  22 , a digital electronic circuit  23 , and a shaft assembly  24 . The control knob  27  may optionally include a second control surface  25  to form a composite control knob assembly  21 . The control knob  27 , and optional second control surface  25  may be plugged into a socket  26 .  
         [0030]    As shown in FIG. 2, a preferred embodiment of a control knob according to the invention may include a knob housing, indicated generally at  22 , having a knob visible surface  30  and a knob display window  31 , which are normally visible to the user of the appliance. The shape of the knob housing  22  is preferably ergonomically designed, for example by including a rib for ease of turning. The knob display window  31  is preferably formed of, or is coated with, a material or surface protectant which is resistant to cleaning chemicals, foods, and scratching. The color of the knob display window  31  may be chosen to reduce the visibility of the knob display window  31  when the display is off, for example when the knob is not in use or the appliance is off.  
         [0031]    In a preferred embodiment, the rotation of the control knob  27  may be limited, for example to plus or minus 15 degrees, so the display on the knob is never hidden by the rotation. The rotation of the control knob  27  may also be spring-loaded so that the control knob  27  returns to its nominal centered position after adjustment.  
         [0032]    As shown in FIG. 2, a preferred embodiment of a control knob according to the invention includes a digital electronic circuit, indicated generally at  23 . The digital electronic circuit  23  includes a display  41 , which is preferably a light emitting diode (LED) or equivalent, such as a liquid crystal display or other electronic display, and a microprocessor  44  or equivalent, such as a microcontroller, programmable logic device, or other digital electronic circuit. In a preferred embodiment, the digital electronic circuit  23  may be constructed using a printed circuit board  40 , one or more capacitors  42 , and a bipolar connector socket  43  to provide an electrical connection between the digital electronic circuit  23  and the shaft assembly  24 .  
         [0033]    As shown in FIG. 2, a preferred embodiment of a control knob according to the invention may include a shaft assembly, indicated generally at  24 . The shaft assembly  24  may include a shaft housing  55 , preferably made of plastic or other insulating material. The shaft housing  55  and the knob housing  22  may be fastened together, for example using washers  52 , an O-ring  53 , and screws  54 , to form a sealed cavity which encloses the electronic circuit  23  and protects the electronic circuit  23  from grease and other kitchen materials which may cause the control knob to malfunction or to become unsanitary.  
         [0034]    The shaft assembly  24  includes a bipolar connector, indicated generally at  60 , which is preferably a standard ¼″ phone plug having a sleeve  57 , an insulator  58 , and a tip  59 . The sleeve  57  and the tip  59  of the bipolar connector  60  are each connected electrically to one of the bipolar connector to circuit board plugs  51 , which may be plugged into the bipolar connector socket  43  on the digital electronic circuit  23 .  
         [0035]    As shown in FIG. 2, a preferred embodiment of a composite control knob assembly according to the invention may include a second control surface  25 . The second control surface  25  may be formed in the shape of a ring, and may have at least one position indicator  65 . The second control surface  25  may also have at least one actuator  66 .  
         [0036]    The bipolar connector  60  may be plugged into a socket, indicated generally at  26 . The socket  26  may have a shaft assembly receiver  68 , to mate with the shaft assembly  24 . The shaft assembly  24  may bear key slots  56 , for example to ensure that the shaft assembly  24  can only be inserted into the socket  26  in one way. The socket  26  may convert rotation of the shaft assembly  24  into a signal, for example an analog resistance or capacitance value or a digital coded value, which may be transmitted to the control system for the appliance (not shown). Presence of the bipolar connector  60  in the socket  26  may be monitored by the control system for the appliance (not shown), so that the appliance may be automatically shut down if the control knob  27  is removed.  
         [0037]    The socket  26  may also have a second control surface receiver  67  which mates with the second control surface actuator  66 . The socket  26  may convert rotation of the second control surface into a signal, for example an analog resistance or capacitance value or a digital coded value, which may be transmitted to the control system for the appliance (not shown).  
         [0038]    FIGS.  3 - 6  provide additional views of a preferred embodiment of a control knob  27  according to the invention. FIG. 7 provides a perspective view of a preferred embodiment of a composite control knob  21  according to the invention. FIGS.  8 - 12  provide additional views of a preferred embodiment of a second control surface  25  according to the invention.  
         [0039]    [0039]FIG. 13 provides a block diagram of the electronic circuitry of a preferred embodiment of a control knob  27  according to the invention. FIG. 14 shows an exemplary layout for an electronic circuit  23  for a preferred embodiment of a control knob according to the invention.  
         [0040]    In a preferred embodiment, a bipolar connector  60 , for example a standard ¼″ phone plug, carries both power and status information on the bipolar connector tip  59 , with the bipolar connector sleeve  57  used as the return or ground. The signal on the bipolar connector tip  59  may carry the status information to be displayed by the knob as serial data, for example RS-232C, and also a carrier voltage, for example +5 volts DC, which may provide power for the electronic circuitry.  
         [0041]    In a preferred embodiment, the signal on the bipolar connector tip  59  alternates between two states, a rest state and a data transmission state. During the rest state, a voltage, for example 5 volts DC, is maintained on the bipolar connector tip  59 . During the data transmission state, a data transmission cycle is initiated by lowering the signal at the input to ground and then transmitting data, for example using RS-232 serial communications.  
         [0042]    In a preferred embodiment, the voltage maintained during the rest state voltage supplies power to the electronic circuit  23 . One or more capacitors  42  may be used to store charge and maintain power to the electronic circuit  23  during the data cycle. Preferably, separate capacitors may be used to provide power to the display  41  and the microprocessor  44 .  
         [0043]    In a preferred embodiment, the microprocessor  44  receives the serial data during the data transmission state, and drives the display  41 , which is preferably a light emitting diode (LED) having a three digit, 7 segment display. The serial data may consist of a single numeric value for display, for example actual oven temperature, or it may consist of multiple numeric values, for example oven temperature setpoint plus actual oven temperature. The serial data may include formatting information, such as color or blinking, in addition to the numeric values.  
         [0044]    There are various possibilities with regard to alternative embodiments and methods including a control knob according to the invention.  
         [0045]    For example, the display  41  may produce more than one color, for example red and black, to match the color of the knob housing or for other aesthetic reasons. The display  41  may also produce more than one color, for example red and green, to indicate different status information, such as error conditions, or preheat cycle, or for other functional reasons.  
         [0046]    Although in a preferred embodiment the rotation of the control knob may be limited to plus or minus 15 degrees, the limit of the rotation may be a lesser or greater selected number of degrees, for example plus or minus 45 degrees, without departing from the spirit of the invention.  
         [0047]    Although in a preferred embodiment, a bipolar connector carries power and status information, other types of connectors could be used having more than two conductors. For example, a tripolar (three conductor) connector such as a stereo phone plug could be used, with one conductor for power, a second conductor for status information, and a third conductor for ground. A tripolar connector could also be used to support multiple displays within a single control knob by using, for example, one conductor for power and status to one display, a second conductor for power and status to a second display, and a third conductor for ground. A tripolar connector could also be used to support bidirectional communication between the control knob and the appliance control system, for example by using one conductor for power and status to one display, a second conductor for status or control information from the knob, and a third conductor for ground.  
         [0048]    Although in a preferred embodiment, the control knob is sealed using washers and O-rings, this result can be accomplished with other means for sealing, for example using glue, sealing tape, tight fitting joints, foam, rubber, threads, or other materials or methods known in the art.  
         [0049]    The display  41  may provide multiple types of information, for example oven temperature setpoint, actual oven temperature, probe setpoint, probe temperature, and error codes. The multiple types of information could be provided at the same time using non-numeric indicators, for example different colors or blinking, or by alternating between two different types of information, for example, by alternating between oven temperature setpoint and actual oven temperature.  
         [0050]    It is understood that the invention is not confined to the embodiments set forth herein as illustrative, but embraces all such forms thereof as come within the scope of the following claims.