Patent Publication Number: US-9890991-B2

Title: Domestic appliance including piezoelectric components

Description:
CROSS-REFERENCE TO RELATED U.S. PATENT APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 61/781,946, filed on Mar. 14, 2013, U.S. Provisional Patent Application No. 61/825,138, filed on May 20, 2013, and U.S. Provisional Patent Application No. 61/825,144, filed on May 20, 2013, all of which are hereby incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to domestic appliances and more particularly to electronic components of a domestic appliance. 
     BACKGROUND 
     Domestic appliances perform various functions in consumer&#39;s homes. For example, a domestic refrigerator is an appliance used to store food items in a home at preset temperatures. A domestic refrigerator typically includes one or more temperature-controlled compartments into which food items may be placed to preserve the food items for later consumption. A domestic refrigerator also typically includes a number of electronic components that control and regulate various operations of the refrigerator. 
     An electric or gas dryer for laundry is an appliance used to dry clothes or other laundry. A dryer typically includes a rotating drum for tumbling the laundry and a gas heater or electric heating element for providing heat to dry the laundry. A dryer also typically includes a number of electronic components that control and regulate various operations of the dryer. 
     An electric washer for laundry is an appliance used to wash clothes or other laundry. A washer typically includes a rotating drum and a fluid inlet for providing washing fluid to wash laundry in the drum. A washer also typically includes a number of electronic components that control and regulate various operations of the washer. 
     SUMMARY 
     According to one aspect of the disclosure, a domestic appliance such as a refrigerator is disclosed. The refrigerator includes a cabinet defining a temperature-controlled compartment and a door positioned at a front of the cabinet. The door is moveable between an open position in which user-access to the temperature-controlled compartment is permitted and a closed position in which user-access to the temperature-controlled compartment is prevented. The refrigerator includes a sensor secured to the door. The sensor includes a piezoelectric device configured to generate electrical power when the door is moved from the open position to the closed position. 
     In some embodiments, the sensor may include a wireless transmitter electrically coupled to the piezoelectric device. The piezoelectric device may be configured to supply electrical power to the wireless transmitter when the door is moved between the open position and the closed position. 
     In some embodiments, the piezoelectric device may include a gasket configured to generate electrical power when compressed, and the sensor may include a plug extending outwardly from an opening defined in the door. The plug may be moveable between a first position in which the plug compresses the gasket and a second position in which the plug is spaced apart from the gasket. 
     Additionally, in some embodiments, when the door is in the closed position, the plug may be in the first position, and when the door is in the open position, the plug may be in the second position. 
     In some embodiments, the refrigerator may include an electrical power generator including a second piezoelectric device extending between the door and the cabinet. The second piezoelectric device may be configured to generate electrical power when the door is moved from the closed position to the open position. 
     In some embodiments, the second piezoelectric device may include a body formed from a stretchable dielectric elastomer. In some embodiments, the body may have a first length when the door is closed and a second length when the door is open. The second length may be greater than the first length. In some embodiments, the second piezoelectric device may include a piezoelectric film element. 
     Additionally, in some embodiments, the refrigerator may include a battery. The second piezoelectric device may be configured to supply electrical power to the battery when the door is moved from the closed position to the open position. 
     According to another aspect, a domestic appliance includes a cabinet defining a compartment, a light source positioned in the compartment, and a door positioned at a front of the cabinet. The door is moveable between an open position in which user-access to the compartment is permitted and a closed position in which user-access to the compartment is prevented. The domestic appliance also includes a sensor secured to the door that includes a transmitter configured to generate an electrical signal when supplied with electrical power and a piezoelectric device configured to supply electrical power to the transmitter when the door is in the closed position. The domestic appliance includes a receiver configured to receive the electrical signal generated by the transmitter and an electronic controller coupled to the receiver and the light source. The controller is configured to detect the electrical signal from the transmitter and de-energize the light source when the electrical signal is detected. 
     In some embodiments, the piezoelectric device may include a gasket configured to generate electrical power when compressed. The sensor may include a plug extending outwardly from an opening defined in the door. The plug may be moveable between a first position in which the plug compresses the gasket and a second position in which the plug is spaced apart from the gasket. 
     In some embodiments, the domestic appliance may include an electrical power generator including a second piezoelectric device extending between the door and the cabinet. The second piezoelectric device may be configured to generate electrical power when the door is moved from the closed position to the open position. The domestic appliance may also include a power supply circuit operable to distribute electrical power generated by the electrical power generator to the light source. 
     Additionally, in some embodiments, the controller may be coupled to the power supply circuit. The controller may be configured to operate the power supply circuit to supply electrical power to the light source when the electrical signal is absent. 
     In some embodiments, the domestic appliance may include a battery coupled to the power supply circuit. The controller may be coupled to the power supply circuit and may be configured to operate the power supply circuit to supply electrical power to the battery. 
     According to another aspect, a method of operating a refrigerator appliance is disclosed. The method includes deflecting a piezoelectric device positioned on a door of the refrigerator appliance to generate a quantity of electrical power, communicating with a sensor to determine the quantity of electrical power generated by the piezoelectric device, and operating a light source of the refrigerator appliance based on the quantity of electrical power. 
     In some embodiments, operating the light source of the refrigerator appliance based on the quantity of electrical power may include de-energizing the light source when the quantity of electrical power is less than a predetermined value. 
     According to another aspect of the disclosure, a dryer appliance is disclosed. The dryer appliance includes a cabinet, and a drum mounted in the cabinet for rotation about a longitudinal axis. The drum includes a chamber sized to receive laundry. The dryer appliance also includes a drive mechanism positioned in the cabinet that is operable to rotate the drum about the longitudinal axis, an electronic controller configured to operate the drive mechanism, and a sensor positioned in the cabinet. The sensor includes a piezoelectric device that is configured to generate electrical power when the drum is rotated about the longitudinal axis. 
     In some embodiments, the sensor may include a wireless transmitter electrically coupled to the piezoelectric device. The wireless transmitter may be configured to generate an electrical signal when supplied with electrical power. The piezoelectric device may be configured to supply electrical power to the wireless transmitter when the drum is rotated about the longitudinal axis. 
     In some embodiments, the dryer appliance may include a receiver configured to receive the electrical signal generated by the transmitter. The electronic controller may be coupled to the receiver and the drive mechanism and may be configured to determine whether the electrical signal has been received from the transmitter and de-energize the drive mechanism when the electrical signal is not received. 
     In some embodiments, the drive mechanism may include a belt coupled to the drum and an idler assembly configured to tension the belt. The piezoelectric device may be secured to the idler assembly. Additionally, in some embodiments, the idler assembly may include an idler pulley and a biasing element configured to bias the belt into engagement with the idler pulley. The biasing element may be configured to deflect when the drum is rotated about the longitudinal axis. The piezoelectric device may be secured to the biasing element and may be configured to generate and supply electrical power to the transmitter when the biasing element is deflected. 
     In some embodiments, the piezoelectric device may include a body formed from a stretchable dielectric elastomer. Additionally, the body may be configured to expand from a first length to a second length when the biasing element is deflected. 
     In some embodiments, the dryer appliance may include a door positioned at a front of the cabinet. The door may be moveable between an open position in which user-access to the chamber of the drum is permitted and a closed position in which user-access to the chamber of the drum is prevented. The dryer appliance may also include an electrical power generator including a second piezoelectric device extending between the door and the cabinet. The second piezoelectric device may be configured to generate electrical power when the door is moved from the closed position to the open position. 
     In some embodiments, the dryer appliance may include a light source configured to illuminate the chamber of the drum, and a power supply circuit operable to distribute electrical power generated by the electrical power generator to the light source. 
     In some embodiments, the dryer appliance may include a battery coupled to the power supply circuit. The electronic controller may be coupled to the power supply circuit and may be configured to operate the power supply circuit to supply electrical power to the battery. 
     In some embodiments, the dryer appliance may include an air system configured to draw heated air through the chamber of the drum when the drum is rotated about the longitudinal axis. The air system may include a duct and a grill positioned between the chamber and the duct. The grill may include a plurality of openings that are sized to permit heated air drawn through the chamber to advance into the duct. When heated air is advanced into the duct through the openings of the grill, the piezoelectric device may be deflected such that the piezoelectric device generates a quantity of electrical power greater than zero watts. 
     In some embodiments, the air system may include a first wall having the grill defined therein. The duct may include a chute connected to the grill, an upper passageway having an end isolated from the chute, and a lower passageway connected to the chute and the upper passageway. The piezoelectric device may be positioned in the passageway. The piezoelectric device may be configured to deflect to a first degree of deflection when heated air is advanced into the lower passageway through the chute and the passageway and a second degree of deflection when the openings of the grill are substantially blocked and heated air is advanced into the lower passageway through the upper passageway. The second degree of deflection may be greater than the first degree of deflection and the quantity of electrical power generated by the piezoelectric device at the second degree of deflection may be greater than the quantity of electrical power generated at the first degree of deflection. 
     In some embodiments, the dryer appliance may include a filter removably coupled to the cabinet. The filter may include a screen and may be moveable between a first position in which the screen is positioned in the chute and a second position in which the screen is removed from the chute. 
     In some embodiments, the piezoelectric device may be configured to deflect to a third degree of deflection when the filter is in the second position and heated air is advanced into the chute and the upper passageway. The third degree of deflection may be less than the first degree of deflection and the quantity of electrical power generated by the piezoelectric device at the third degree of deflection may be less than the quantity of electrical power generated at the first degree of deflection. 
     In some embodiments, the sensor may be configured to generate an electrical signal indicative of the quantity of electrical power generated by the piezoelectric device. 
     In some embodiments, the electronic controller may be configured to communicate with the sensor to determine the quantity of electrical power generated by the piezoelectric device, compare the quantity of electrical power to a predetermined value, and de-energize the drive mechanism when the quantity of electrical power generated by the piezoelectric device is less than the predetermined value. 
     According to another aspect, a domestic appliance is disclosed. The appliance includes a drum mounted for rotation about a longitudinal axis and including a chamber sized to receive laundry. The appliance also includes a drive mechanism operable to rotate the drum about the longitudinal axis. The drive mechanism includes an idler pulley, a belt engaged with the drum and the idler pulley, and a biasing element configured to bias the belt into engagement with the idler pulley. The biasing element is configured to deflect when the drum is rotated about the longitudinal axis. 
     The domestic appliance also includes a sensor including a transmitter configured to generate an electrical signal when supplied with electrical power, and a piezoelectric device secured to the biasing element. The piezoelectric device is configured to supply electrical power to the transmitter when the biasing element is deflected. The appliance includes a receiver configured to receive the electrical signal generated by the transmitter and an electronic controller coupled to the receiver and the drive mechanism. The electronic controller is configured to detect the electrical signal from the transmitter and de-energize the drive mechanism when the electrical signal is not detected. 
     According to another aspect, a method of operating a dryer appliance is disclosed. The method includes deflecting a piezoelectric device positioned in a cabinet of the dryer appliance to generate a quantity of electrical power, communicating with a sensor to determine the quantity of electrical power generated by the piezoelectric device, and operating a drive mechanism of the dryer appliance based on the quantity of electrical power. 
     In some embodiments, deflecting the piezoelectric device to generate the quantity of electrical power may include advancing heated air through a passageway defined in the cabinet to bend the piezoelectric device. In some embodiments, operating the drive mechanism of the dryer appliance based on the quantity of electrical power may include de-energizing the drive mechanism when the quantity of electrical power is less than a predetermined value. 
     According to another aspect of the disclosure, a laundry appliance is disclosed. The laundry appliance includes a tub configured to contain a washing fluid and a drum mounted for rotation within the tub about a longitudinal axis. The drum includes a chamber sized to receive laundry. The laundry appliance also includes a drive mechanism operable to rotate the drum about the longitudinal axis, an electronic controller configured to operate the drive mechanism, and a piezoelectric power generator configured to generate electrical power when the drum is rotated about the longitudinal axis. 
     In some embodiments, the laundry appliance may include an electrical component powered by the piezoelectric power generator. In such an embodiment, the piezoelectric power generator may be mounted on the drum. The electrical component may be powered solely by the piezoelectric power generator. 
     In some embodiments, the laundry appliance may include an active balancing system to balance a load in the drum, and the active balancing system may include the electrical component. The drum may include a plurality of compartments defined therein in which each compartment is configured to receive fluid. The drum may also include an electrically-operated pump configured to move the fluid between the plurality of compartments to balance the load in the drum. In such an embodiment, the electrical component may include the electrically-operated pump. 
     In some embodiments, the drum may include a plurality of balance balls configured to balance a load in the drum and an electrically-operated actuator configured to regulate the plurality of the balance balls. In such an embodiment, the electrical component may include the electrically-operated actuator. In some embodiments, the electrically-operated actuator may include a sensor having a second piezoelectric power generator. The sensor may be configured to transmit a signal associated with electrical power generated by the second piezoelectric power generator to the electronic controller. 
     In some embodiments, the sensor may include a wireless transmitter electrically coupled to the second piezoelectric power generator. The wireless transmitter may be configured to transmit a signal to the electronic controller when supplied with electrical power from the second piezoelectric power generator. In some embodiments, the drum may include a baffle extending from an inner wall that defines the chamber and the piezoelectric power generator may be mounted on the blade and configured to generate the electrical power when the blade is deflected. In such an embodiment, the baffle may include a blade configured to engage contents of the chamber of the drum and to deflect from a force applied to the blade by the contents when the drum is rotated. 
     In some embodiments, the laundry appliance may include a cabinet, a damper, and an electrical component. The damper may be mounted in the cabinet and may include a first end coupled to the cabinet and a second end coupled to the tub. The electrical component may be powered by the piezoelectric power generator and may include a force sensor configured to sense a force applied to the damper. Additionally, the piezoelectric power generator may be coupled to the damper. 
     In some embodiments, the laundry appliance may include a cabinet and a seal. In such an embodiment, the seal may be coupled to the cabinet and to a rim of the tub at an end defining an opening to the chamber. Additionally, the piezoelectric power generator may be coupled to the seal and configured to generate the electrical power based on stretching of the seal. In some embodiments, the laundry appliance may include a mold sensor coupled to the seal and configured to detect a presence of mold. 
     In some embodiments, the piezoelectric power generator may include a body formed from a stretchable dielectric elastomer. In another embodiment, the laundry appliance may include a power supply circuit electrically coupled to the piezoelectric power generator. Additionally, the power supply circuit may be operable to store and distribute electrical power generated by the piezoelectric power generator. The power supply circuit may include at least one of a battery and a capacitor. 
     According to another aspect, another laundry appliance is disclosed. The appliance includes a tub, a drum, a drive mechanism, a piezoelectric power generator, and an electronic controller. The tub is configured to contain a washing fluid. The drum is mounted for rotation within the tub about the longitudinal axis, and includes a chamber sized to receive laundry. The drive mechanism is operable to rotate the drum about the longitudinal axis. Additionally, the piezoelectric power generator is positioned on the drum and is configured to generate an electrical signal when the drum is rotated about the longitudinal axis. The electronic controller is configured to operate the drive mechanism based on the electrical signal received from the piezoelectric power generator. 
     In some embodiments, the drum may include a plurality of compartments defined therein. Each compartment may be configured to receive fluid. Additionally, the drum may include an electrically-operated pump configured to move the fluid between the plurality of compartments to balance the load in the drum. Further, the piezoelectric power generator may be electrically coupled to the electrically-operated pump. In some embodiments, the drum may include a plurality of balance balls configured to balance a load in the drum and an electrically-operated actuator configured to regulate the plurality of the balance balls. In such an embodiment, the piezoelectric power generator may be electrically coupled to the electrically-operated actuator. 
     According to another aspect, a method for utilizing power in a laundry appliance is disclosed. The method includes operating a laundry appliance to rotate a drum containing laundry and wash fluid about a longitudinal axis, generating electrical power from a piezoelectric power generator based on movement of a component of the laundry appliance, and supplying electrical power generated by the piezoelectric power generator to an electrical component of the laundry appliance. In some embodiments, the piezoelectric power generator may be mounted on the drum. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description particularly refers to the following figures, in which: 
         FIG. 1  is a front elevation view of a domestic refrigerator. 
         FIG. 2  is a top plan view of the domestic refrigerator of  FIG. 1  showing a door in an open position and a closed position. 
         FIG. 3  is a block diagram of the domestic refrigerator of  FIG. 1 . 
         FIG. 4  is a diagrammatic top plan view of a door position sensor of the domestic refrigerator of  FIG. 1 . 
         FIG. 5  is a diagrammatic top plan view of a mullion position sensor of the domestic refrigerator of  FIG. 1 . 
         FIG. 6  is a plan view of an upper power generator of the domestic refrigerator of  FIG. 1 . 
         FIG. 7  is a view similar to  FIG. 6  showing a door of the domestic refrigerator in an open position. 
         FIG. 8  is a plan view of a lower power generator of the domestic refrigerator of  FIG. 1  with the door in a closed position. 
         FIG. 9  is a view similar to  FIG. 8  showing the door in an open position. 
         FIG. 10  is a front perspective view of a dryer appliance. 
         FIG. 11  is a simplified block diagram of the dryer appliance of  FIG. 10 . 
         FIG. 12  is a partial elevation view of the drive mechanism of the dryer appliance of  FIG. 10 . 
         FIG. 13  is a partial elevation view of the interior of the dryer appliance of  FIG. 10 . 
         FIG. 14  is a perspective view of a filter screen of the dryer appliance of  FIG. 1 . 
         FIG. 15  is a cross-sectional elevation view taken along the line  6 - 6  of  FIG. 14 . 
         FIG. 16  is a perspective view of another embodiment of a dryer appliance. 
         FIG. 17  is a cross-sectional elevation view taken along the line  8 - 8  of  FIG. 16 . 
         FIG. 18  is a front perspective view of a washer appliance; 
         FIG. 19  is a cross-sectional side elevation view of the washer appliance of  FIG. 18 . 
         FIG. 20  is a simplified block diagram of the washer appliance of  FIG. 18 ; 
         FIG. 21  is an exploded perspective view of one embodiment of an active balancing system of the washer appliance of  FIG. 18 ; and 
         FIG. 22  is an exploded perspective view of another embodiment of an active balancing system of the washer appliance of  FIG. 18 . 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the concepts of the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure. 
     Referring to  FIG. 1 , a home appliance is shown as a domestic refrigerator appliance  10  (hereinafter refrigerator  10 ). The refrigerator  10  includes a cabinet  12  and a lower frame  14  that supports the cabinet  12 . The refrigerator cabinet  12  defines a temperature-controlled, refrigerated compartment  16  into which a user may place and store food items such as milk, cheese, produce, etcetera. The refrigerated compartment  16  is operable to maintain stored food items at a predefined temperature. 
     As shown in  FIG. 1 , the refrigerator cabinet  12  defines a temperature-controlled freezer compartment  18 , which is also operable to maintain food items stored therein at a certain temperature. The refrigerator  10  includes a drawer  20  that permits user access to the freezer compartment  18  such that food items may be placed in and retrieved from shelves and drawers positioned therein. When the drawer  20  is in the closed position shown in  FIG. 1 , user access to the freezer compartment  18  is prevented. A handle  22  is located on the drawer  20 , and the user may use the handle  22  to pull the drawer  20  open. It will be appreciated that in other embodiments the freezer compartment may be positioned above or side-by-side with the refrigerated compartment  16 , either as a free standing refrigerator or a built-in refrigerator. It will be further appreciated that in other embodiments the refrigerator  10  may not have a freezer compartment. It should also be appreciated that the concepts described herein may be included in a stand-alone freezer such as, for example, a chest freezer. The concepts described herein also may be included in other domestic appliances such as, for example, microwaves, ovens, dishwashers, laundry appliances, and so forth. 
     The refrigerator  10  includes a right-hand door  24  and a left-hand door  26  that permit user access to the refrigerated compartment  16  such that food items may be placed in and retrieved from the refrigerator  10 . The right-hand door  24  is hinged to the front of the refrigerator cabinet  12  via an upper hinge assembly  28  and a lower hinge assembly  30 . A handle  32  is located on a front panel  34  of the door  24 , and the user may use the handle  32  to pull the right-hand door  24  open. The left-hand door  26  is hinged to the front of the refrigerator cabinet  12  via another upper hinge assembly  28  and a lower hinge assembly  36 . Another handle  32  is located on a front panel  38  of the door  26 , and the user may use that handle  32  to pull the left-hand door  26  open. Each of the doors  24 ,  26  also includes a back panel  40  and a number of shelves  42  extending from back panel  40 . A gasket  44  is attached to each of the doors  24 ,  26  at the outer perimeter of the back panel  40 . 
     The cabinet  12  of the refrigerator  10  includes a number of side walls  50  that extend upwardly from a bottom wall  52  to a top wall  54 . The walls  50 ,  52 ,  54  cooperate to define the refrigerated compartment  16 . As shown in  FIG. 1 , a number of shelves  60  are positioned in the compartment  16 . The cabinet  12  has an open front side  56  that defines an access opening  58 , which provides user access to shelves  42 ,  60  of the refrigerator  10  when either of the doors  24 ,  26  is open. When the doors  26  are closed, the gaskets  44  cooperate with a mullion bar  62  to seal the access opening  58  and thereby prevent the user from accessing the shelves  42 ,  60  and preventing chilled air from escaping through the access opening  58 . 
     In the illustrative embodiment, the mullion bar  62  includes a central body  64  that is attached to the left-hand door  26  via a pair of hinges assemblies  66 . It should be appreciated that in other embodiments the mullion bar  62  may be secured to the right-hand door  24 . As shown in  FIGS. 1 and 2 , the mullion bar  62  is configured to pivot between a retracted position (shown in solid line) when the door  26  is open and an extended position (shown in broken line) when the door  26  is closed, as described in greater detail below. The refrigerator  10  includes a locking mechanism  68  for the mullion bar  62 . The locking mechanism  68  retains the mullion bar  62  in the retracted position when the door  26  is open and releases the mullion bar  62  to move to the extended position as the door  26  is closed. The locking mechanism  68  may be embodied as a magnetic retaining element, spring biased lock, or other mechanism. One example of a locking mechanism  68  is shown and described in U.S. Pat. No. 7,008,032 entitled “Refrigerator Incorporating French Doors With Rotating Mullion Bar,” which issued on Mar. 7, 2006 and is incorporated herein by reference. 
     A guide pin  70  extends upwardly from the central body  64  of the mullion bar  62 . As shown in  FIG. 2 , the guide pin  70  includes a front cam surface  72  and a rear cam surface  74  positioned opposite the front cam surface  72 . In the illustrative embodiment, the front cam surface  72  is a convex, curved surface, and the rear cam surface  74  is a concave, curved surface. It should be appreciated that in other embodiments the surfaces  72 ,  74  may include one or more flat surfaces. 
     The guide pin  70  is received in a guide block  80  when the door  26  is closed. As shown in  FIG. 2 , the guide block  80  includes an outer wall  82  that extends downwardly from the top wall  54  of the cabinet  12 . An opening  84  is defined in the front surface  86  of the outer wall  82 . A number of guide surfaces  88  extend inwardly from the opening  84  to define a slot or track  90  sized to receive guide pin  70 . The guide surfaces  88  include a sloping curved surface  92  that extends inwardly from the opening  84  to an edge  94 . The guide surfaces  88  also include a substantially flat surface  96  that is connected to the surface  92  at the edge  94 . A convex surface  98  is positioned opposite the surface  92 , and the surface  98  defines a projection  100  extending into the track  90 . 
     When the door  26  is in the closed position shown in  FIG. 2 , the mullion bar  62  is in the extended position, and the rear cam surface  74  of the guide pin  70  engages the projection  100  of the guide block  80 . As the door  26  is opened, the guide pin  70  is forced to pivot around the projection  100 , thereby causing the central body  64  of the mullion bar  62  to rotate in the direction indicated by arrow  102  from the extended position to the retracted position. Once the mullion bar  62  is in the retracted position, the locking mechanism  68  retains the bar  62  in that position until the door  26  is closed. 
     When the door  26  is moved from the open position to the closed position, the guide pin  70  is passed through the opening  84  of the guide block  80 , and the front cam surface  72  is advanced into contact with the curved surface  92  of the block  80 . The engagement between the front cam surface  72  and the curved surface  92  causes the guide pin  70  to pivot, thereby causing the central body  64  of the mullion bar  62  to rotate from the retracted position. As the mullion bar  62  is rotated, the front cam surface  72  advances along the curved surface  92  and the flat surface  96 , and the rear cam surface  74  of the guide pin  70  engages the projection  100 . When the mullion bar  62  is in the extended position, the rear cam surface  74  of the guide pin  70  engages the projection  100  of the guide block  80  as shown in  FIG. 2 . 
     Referring now to  FIG. 3 , the refrigerator  10  is shown in a simplified block diagram. The refrigerator  10  includes a control panel  104  that is secured to the door  26 . The control panel  104  includes a number of controls  106 , such as buttons, knobs, and/or a touchscreen panel that are used to control the operation of the refrigerator  10 . In other embodiments, the touchscreen panel may be the sole control located on the control panel  104 , thus permitting a user to control all user accessible operations of the refrigerator  10  via the touchscreen panel. Additionally, in other embodiments, the control panel  104  may include a display panel such as a liquid crystal display (LCD) panel or some other type of display panel along with one or more buttons associated with the display panel that may be actuated to control operation of the refrigerator  10 . In other embodiments, the control panel may include only buttons and knobs that may be actuated to control operation of the refrigerator  10 . 
     The refrigerator  10  also includes a power supply circuit  110 . The components of the power supply circuit  110  may be located in any suitable portion of the refrigerator  10 , including, but not limited to, the lower frame  14  or the cabinet  12 . It should be appreciated that the power supply circuit  110  may include components, sub-components, and devices other than those shown in  FIG. 3 , which are not illustrated for clarity of the description. 
     As shown in  FIG. 3 , the power supply circuit  110  may be electrically coupled to an AC mains power source  112 , such as, for example, an electrical outlet commonly found in residential homes. The AC mains power source  112  is electrically coupled to a DC power converter of the power supply circuit  110  via a number of signal paths. These signal paths and other signal paths illustrated in  FIG. 3  may be embodied as any type of signal paths capable of communicating electrical signals between the components of the power supply circuit  110 . For example, the signal paths may be embodied as any number of wires, cables, printed circuit board traces, bus, intervening devices, and/or the like. 
     The power supply circuit  110  is electrically coupled to a number of electrical components  116  of the refrigerator  10 . In the illustrative embodiment, the electrical components  116  include a plurality of lighting devices  118  for illuminating food items placed in the refrigerated compartment  16  and another plurality of lighting devices  118  for illuminating food items placed in the freezer compartment  18 . The electrical components  116  also include a compressor  120  that is operable to regulate the temperature of the refrigerated compartment  16  and the temperature of the freezer compartment  18 . 
     A door position sensor  122  is attached to the door  26  to indicate the position of the door  26  relative to the cabinet  12 . It should be appreciated that in the illustrative embodiment the door  24  also has a door position sensor (not shown) attached thereto that indicates the position of the door  24  relative to the cabinet  12 . As shown in  FIGS. 1 and 4 , the back panel  40  of the door  26  has an opening  124  defined therein, and a number of inner walls  126  extend inwardly from the opening  124  to define an aperture  130  in the door  26 . The position sensor  122  includes a plug  132  that is positioned in the aperture  130 . In the illustrative embodiment, a pair of guide pins  134  extend outwardly from the plug  132 , and each guide pin  134  is received in a corresponding slot  136  defined in each inner wall  126  of the door  26 . 
     The plug  132  is configured to move relative to the opening  124  between an extended position when the door  26  is open and a retracted position when the door  26  is closed. When the plug  132  is in the retracted position (i.e., the door  26  is closed), the outer face  138  of the plug  132  is aligned with the back panel  40 . When the plug  132  is in the extended position (i.e., the door  26  is open) shown in  FIG. 4 , the plug  132  extends outwardly from the opening  124 , and the pins  134  engage stops  140  formed at the ends of the slots  136  such that the plug  132  is retained in the aperture  130 . In the illustrative embodiment, the position sensor  122  also includes a biasing element such as, for example, spring  142  configured to bias the plug  132  in the extended position. 
     The position sensor  122  also includes an array of piezoelectric elements  144  that are positioned in the aperture  130 . Each piezoelectric element  144  is configured to generate electrical power when the plug  132  is moved between the extended position and the retracted position. Each of the piezoelectric elements  144  is embodied as a compressible gasket  146 , which is formed from a piezoelectric ceramic, such as, for example, lead zirconate titanate (PZT). As shown in  FIG. 4 , the plug  132  includes a rib  150 , which is configured to engage and compress each gasket  146  as the plug  132  is moved to the retracted position. When each piezoelectric gasket  146  is compressed, electrical power is generated. It should be appreciated that in other embodiments the piezoelectric element may take other forms, such as, for example, a piezoelectric disk that generates a voltage when deformed. In other embodiments, the piezoelectric element may also be formed from an electroactive polymer (EAP) such as, for example, a stretchable dielectric elastomer. 
     In the illustrative embodiment, the spring  142  biases the plug  132  in the extended position. When a sufficient force is applied in the direction indicated by arrow  148  such as, for example, when the door  26  is closed, the bias exerted by the spring  142  is overcome, and the plug  132  is moved from the extended position. The rib  150  is advanced into engagement with gaskets  146 , and the gaskets  146  are compressed as the plug  132  is moved to the retracted position. When the plug  132  is in the retracted position, the piezoelectric elements  144  generate a predetermined amount of electrical power. In the illustrative embodiment, the predetermined amount or quantity of power is approximately 1 Watt. It should be appreciated that in other embodiments the power may range from approximately 500 μW to 1 Watt. When the door  26  is opened, the bias exerted by the spring  142  urges the plug  132  outward to the extended position, thereby permitting the gaskets  146  to expand. 
     The piezoelectric gaskets  146  of the position sensor  122  are electrically connected to transmitter circuitry  156 . The transmitter circuitry  156  is configured to transmit a wireless data signal when energized. In the illustrative embodiment, the transmitter circuitry  156  uses a Bluetooth transmission protocol. The electrical power generated by the piezoelectric gaskets  146  energizes the transmitter circuitry  156  such that the wireless data signal is transmitted. In that way, the position sensor  122  does not require power from the power supply circuit  110  (and hence the AC mains power source  112 ). 
     In use, when the door  26  is closed, the transmitter circuitry  156  is energized and generates the wireless data signal. Alternatively, when the door  26  is opened, piezoelectric gaskets  146  are permitted to expand such that the electrical power generated is decreased. As a result, the transmitter circuitry  156  is de-energized such that no wireless data signal is generated. 
     In other embodiments, the transmitter circuitry  156  may be configured to transmit via a local area network, infrared communication, or other wireless communication protocol. It should also be appreciated that in other embodiments the transmitter circuitry  156  may be replaced with a Radio-Frequency Identification (RFID) tag. When the piezoelectric elements  144  are generating electrical power, the RFID tag may be energized to transmit a wireless signal. 
     The refrigerator  10  also includes a mullion position sensor  160 , which indicates the position of the mullion bar  62 . As shown in  FIG. 5 , the guide block  80  of the refrigerator  10  has a pair of openings  162  defined in a guide surface  164  thereof. A number of inner walls  166  extend inwardly from each opening  162  to define a pair of apertures  168  in the guide block  80 . The position sensor  160  includes a plug  170  that is positioned in each aperture  168 . In the illustrative embodiment, a pair of pins  172  extend outwardly from each plug  170 , and each pin  172  is received in a corresponding slot  174  defined in each inner wall  166  of the guide block  80 . 
     Each plug  170  is configured to move relative to the opening  162  between a retracted position and an extended position. When the door  26  is closed and the mullion bar  62  is positioned in the guide block  80 , the plugs  170  are in the retracted position. The plugs  170  are in the extended position when the door  26  is open and the mullion bar  62  is spaced apart from the guide block  80 . In the illustrative embodiment, the guide pin  70  of the mullion bar  62  engages the outer face  176  of each plug  170  when the bar  62  is positioned in the guide block  80 . When the plugs  170  are in the extended position (i.e., the door  26  is open), the plugs  170  extends outwardly from the openings  162 , and the pins  172  engage stops  178  formed at the ends of the slots  174  such that the plugs  170  are retained in the apertures  168 . In the illustrative embodiment, the position sensor  122  also includes a biasing element such as, for example, spring  180  configured to bias each plug  170  in the extended position. 
     The position sensor  160  also includes an array of piezoelectric elements  182  configured to generate electrical power when the plugs  170  are moved between the extended position and the retracted position. Similar to the piezoelectric elements  144  of the door position sensor  122 , the piezoelectric elements  182  are embodied as compressible gaskets  184 . Each gasket  184  is formed from a piezoelectric ceramic, such as, for example, lead zirconate titanate (PZT). As shown in  FIG. 5 , each plug  170  includes a rib  186 , which is configured to engage and compress each gasket  184  as the plug  170  is moved to the retracted position. When each piezoelectric gasket  184  is compressed, electrical power is generated. It should be appreciated that in other embodiments the piezoelectric element may take other forms, such as, for example, a piezoelectric disk that generates a voltage when deformed. In other embodiments, the piezoelectric element may also be formed from an electroactive polymer (EAP) such as, for example, a stretchable dielectric elastomer. 
     In the illustrative embodiment, the springs  180  bias the plugs  170  in the extended position. When a sufficient force is applied in the direction indicated by arrows  188  such as, for example, when the mullion bar  62  is positioned in the guide block  80 , the bias exerted by the springs  180  is overcome, and the plug  170  is moved from the extended position. The rib  186  is advanced into engagement with gaskets  184 , and the gaskets  184  are compressed as the plugs  170  are moved to the retracted position. When the plugs  170  are in the retracted position, the piezoelectric elements  182  generate a predetermined amount of electrical power. In the illustrative embodiment, the predetermined quantity of power is approximately 1 Watt. It should be appreciated that in other embodiments the power may range from approximately 500 μW to 1 Watt. When the mullion bar  62  is withdrawn from the guide block  80 , the bias exerted by the springs  180  urge the plug  170  outward to the extended position, thereby permitting the gaskets  184  to expand. 
     The piezoelectric gaskets  184  of the position sensor  160  is electrically connected to transmitter circuitry  190 . The transmitter circuitry  190  is configured to transmit a wireless data signal when energized. In the illustrative embodiment, the transmitter circuitry  190  uses a Bluetooth transmission protocol. The electrical power generated by the gaskets  184  energizes the transmitter circuitry  190  such that the wireless data signal is transmitted. In that way, the position sensor  160  does not require power from the power supply circuit  110  (and hence the AC mains power source  112 ). 
     In use, when the mullion bar  62  is positioned in the guide block  80  and engaged with the plugs  170 , the transmitter circuitry  190  is energized and generates the wireless data signal. Alternatively, when the door  26  is opened, piezoelectric gaskets  184  are permitted to expand such that the electrical power generated is decreased. As a result, the transmitter circuitry  190  is de-energized such that no wireless data signal is generated. 
     In other embodiments, the transmitter circuitry  190  may be configured to transmit via a local area network, infrared communication, or other wireless communication protocol. It should also be appreciated that in other embodiments the transmitter circuitry  190  may be replaced with a Radio-Frequency Identification (RFID) tag. When the piezoelectric gaskets  184  are compressed and generating electrical power, the RFID tag may be energized to transmit a wireless signal. 
     As shown in  FIG. 3 , the refrigerator  10  includes a wireless receiver  192  that is configured to receive the data signals generated by the position sensors  122 ,  160 . In the illustrative embodiment, the receiver  192  is configured to use the Bluetooth transmission protocol. It should be appreciated that the receiver  192  may be embodied as any type of wireless receiver capable of receiving the data signals from the sensors  122 ,  160 . For example, the wireless receiver may be embodied as a wireless router. The wireless receiver  192  is communicatively coupled to an electronic control unit (ECU) or “electronic controller”  200  via a number of communication links  194  such as wires, cables, or the like. 
     The electronic controller  200  of the refrigerator  10  is positioned in the cabinet  12 . The electronic controller  200  is, in essence, the master computer responsible for interpreting electrical signals sent by sensors associated with the refrigerator  10  and for activating or energizing electronically-controlled components associated with the refrigerator  10 . For example, the electronic controller  200  is configured to control operation of the various components of the refrigerator  10 , including the lighting devices  118 , compressor  120 , and the operation of the power circuit  110 . The electronic controller  200  also monitors various signals from the control panel  104 , the door position sensor  122 , the mullion position sensor  160 , and any other sensor. The electronic controller  200  also determines when various operations of the refrigerator  10  should be performed. As will be described in more detail below, the electronic controller  200  is operable to control the components of the refrigerator  10  such that the refrigerator  10  solicits user input regarding refrigerator performance and adjusts operational parameters of the refrigerator  10  in response thereto. 
     To do so, the electronic controller  200  includes a number of electronic components commonly associated with electronic units utilized in the control of electromechanical systems. For example, the electronic controller  200  may include, amongst other components customarily included in such devices, a processor such as a microprocessor  202  and a memory device  204  such as a programmable read-only memory device (“PROM”) including erasable PROM&#39;s (EPROM&#39;s or EEPROM&#39;s). The memory device  204  is provided to store, amongst other things, instructions in the form of, for example, a software routine (or routines) which, when executed by the microprocessor  202 , allows the electronic controller  200  to control operation of the refrigerator  10 . 
     The electronic controller  200  also includes an analog interface circuit  206 . The analog interface circuit  206  converts the output signals from the receiver  192  into signals which are suitable for presentation to an input of the microprocessor  202 . In particular, the analog interface circuit  206 , by use of an analog-to-digital (A/D) converter (not shown) or the like, converts the analog signals generated by the sensors into digital signals for use by the microprocessor  202 . It should be appreciated that the A/D converter may be embodied as a discrete device or number of devices, or may be integrated into the microprocessor  202 . It should also be appreciated that if any one or more of the sensors associated with the refrigerator  10  generate a digital output signal, the analog interface circuit  206  may be bypassed. 
     Similarly, the analog interface circuit  206  converts signals from the microprocessor  202  into output signals which are suitable for presentation to the electrically-controlled components associated with the refrigerator  10  (e.g., the lighting devices  118 ). In particular, the analog interface circuit  206 , by use of a digital-to-analog (D/A) converter (not shown) or the like, converts the digital signals generated by the microprocessor  202  into analog signals for use by the electronically-controlled components associated with the refrigerator  10 . It should be appreciated that, similar to the A/D converter described above, the D/A converter may be embodied as a discrete device or number of devices, or may be integrated into the microprocessor  202 . It should also be appreciated that if any one or more of the electronically-controlled components associated with the refrigerator  10  operate on a digital input signal, the analog interface circuit  206  may be bypassed. 
     Thus, the electronic controller  200  may control the operation of the refrigerator  10 . In particular, the electronic controller  200  executes a routine including, amongst other things, a control scheme in which the electronic controller  200  monitors the outputs of the sensors associated with the refrigerator  10 , including the door position sensor  122  and the mullion position sensor  160 , to control the inputs to the electronically-controlled components associated therewith. To do so, the electronic controller  200  communicates with the sensors directly or indirectly through the wireless receiver  192  to determine, amongst numerous other things, the position of the doors  24 ,  26 . Armed with this data, the electronic controller  200  performs numerous calculations, either continuously or intermittently, including looking up values in preprogrammed tables, in order to execute algorithms to perform such functions as activating the lighting devices  118 , energizing the compressor  120 , activating an indicator on the control panel  104 , and so on. 
     As shown in  FIG. 6 , the refrigerator  10  includes an upper hinge assembly  28  of the refrigerator  10  attached to the upper end  214  of the cabinet  12 . The upper hinge assembly  28  includes a hinge bracket  210  and a hinge pin  212  attached to the hinge bracket  210 . In the illustrative embodiment, the hinge bracket  210  and the hinge pin  212  are formed as a single monolithic component from a metallic material, such as, for example, steel. 
     A piezoelectric power generator  216  is secured to the bracket  210 . The generator  216  configured to generate electrical power when the door  24  is moved between the closed position and the open position, as described in greater detail below. It should be appreciated that in the illustrative embodiment the door  26  also has one or more piezoelectric power generators (not shown) attached thereto that generates electrical power when the door  26  is opened and closed. In the illustrative embodiment, the generator  216  is embodied as an array of piezoelectric film elements  218 . An exemplary film element is the LDT1-028K Piezo Sensor, which is commercially available from Seeed Studio of Shenzhen, China. As show in  FIG. 6 , each element  218  has a first end  220  secured to the door  24  and a second end  222  secured to the cabinet  12 . It should be appreciated that the film elements  218  may be formed from piezoelectric ceramics, such as, for example, lead zirconate titanate (PZT). In other embodiments, the piezoelectric elements may also be formed from an electroactive polymer (EAP) such as, for example, a stretchable dielectric elastomer. 
     When the door  24  is opened, the piezoelectric film elements  218  are bent as shown in  FIG. 7 . As each element  218  is bent, the element  218  generates electrical power proportional to the degree of bending. The electrical power generated by the each element  218  therefore increases as the door  24  is moved to the open position. When the door  24  is in the open position, the electrical power exceeds a predetermined quantity of power. In the illustrative embodiment, the predetermined quantity of power is approximately 1 Watt. It should be appreciated that in other embodiments the power may range from approximately 500 μW to 1 Watt. 
     As shown in  FIG. 3 , the generator  216  is electrically connected to the power supply circuit  110 . When electrical power is produced by the generator  216 , the controller  200  is configured to operate the power supply circuit  110  to direct the power to one of the other electrical components  116  of the refrigerator  10 . For example, the power produced by the generator  216  may be directed through the power supply circuit  110  to the lighting devices  118 . The controller  200  may also operate the power supply circuit  110  to direct the electrical power to a battery  230  for storage and later use. 
     As shown in  FIGS. 8 and 9 , the refrigerator  10  includes another piezoelectric power generator  240 . The generator  240  is configured to generate electrical power when the door  24  is moved between the closed position and the open position, as described in greater detail below. In the illustrative embodiment, the generator  240  is formed from an electroactive polymer (EAP) such as, for example, a stretchable dielectric elastomer, which generates electrical power when deformed. In other embodiments, the generator  240  may be formed as a spring or disk from a piezoelectric ceramic, such as, for example, lead zirconate titanate (PZT). 
     The generator  240  has a body  244  that is positioned below the door  24 . The body  244  has an end  246  that is secured to the lower front surface  248  of the cabinet  12  and another end  250  secured to the lower end  252  of the door  24 . As shown in  FIGS. 8 and 9 , the end  246  of the body  244  is attached to the surface  248  via a joint  254 . In the illustrative embodiment, the joint  254  includes a pin  256  that extends through the body  244  and a bracket  258  secured to the cabinet surface  248 . The joint  254  permits the body  244  of the generator  240  to pivot relative to the cabinet  12 . 
     The opposite end  250  of the body  244  is attached to the surface  248  via a joint  260 . In the illustrative embodiment, the joint  260  includes a pin  262  that extends through the body  244  and a hole (not shown) defined in the lower end  252  of the door  24 . The joint  260  permits the body  244  of the generator  240  to pivot relative to the door  24 . 
     When the door  24  is opened, the body  244  of the generator  240  is stretched and deformed. As shown in  FIG. 8 , the body  244  has an initial length  270  when the door  24  is closed. As the door  24  is opened, the body  244  stretches to a length  272 , as shown in  FIG. 9 . As the body  244  is stretched, the body  244  generates electrical power proportional to the amount of deformation. The electrical power generated by the body  244  therefore increases as the door  24  is moved to the open position. When the door  24  is in the open position, the electrical power exceeds a predetermined quantity of power. In the illustrative embodiment, the predetermined quantity of power is approximately 1 Watt. It should be appreciated that in other embodiments the power may range from approximately 500 μW to 1 Watt. 
     As shown in  FIG. 3 , the generator  240  is electrically connected to the power supply circuit  110 . When electrical power is produced by the generator  240 , the controller  200  is configured to operate the power supply circuit  110  to direct the power to one of the other electrical components  116  of the refrigerator  10 . For example, the power produced by the generator  240  may be directed through the power supply circuit  110  to the lighting devices  118 . The controller  200  may also operate the power supply circuit  110  to direct the electrical power to the battery  230  for storage and later use. 
     In use, a user may open the doors  24 ,  26  to access food items positioned in the refrigerated compartment  16 . To do so, the user may grasp the handle  32  and pull the door  26  open. As the door  26  is opened, the bias exerted by the spring  142  of the door position sensor  122  urges the plug  132  outward to the extended position. As the spring  142  is expanded, the electrical power generated by the piezoelectric gaskets  146  is reduced, and the transmitter circuitry  156  of the position sensor  122  is de-energized such that no wireless data signal is generated. 
     As described above, the electrical power generators  216 ,  240  are operable to produce electrical power when the door  24  is opened. As the door  24  is opened, the film elements  218  of the generator  216  bend and generate electrical power proportional to the degree of bending. Similarly, the body  244  of the generator  240  stretches as the door  24  opens and generates electrical power proportional to the amount of deformation. 
     The controller  200  detects the loss of signal from the sensor  122  and generates an electrical output signal to operate the power supply circuit  110 . In response to the receiving the signal from the controller  200 , the circuit  110  supplies power to, for example, the lighting devices  118  to illuminate the compartment  16 . The power supply circuit  110  may direct the electrical power supplied by the generators  216 ,  240  to energize the lighting devices  118  or to the battery  230  for storage. Additionally, or alternatively, the power supply circuit  110  may supply power from the ac mains power source  112  to energize the lighting device  118 . 
     When the doors  24 ,  26  are closed, the power generated by the electrical power generators  216 ,  240  decreases to approximately zero. The piezoelectric gaskets  146  of the door position sensor  122  are compressed by the rib  150  as the plug  132  is moved from the extended position such that the gaskets  146  generate electrical power. When the door  26  is closed, the transmitter circuitry  156  of the door position sensor  122  is energized and generates the wireless data signal. The controller  200  detects the signal from the sensor  122  and generates an electrical output signal to operate the power supply circuit  110  to, for example, deenergize the lighting devices  118 . 
     As the door  26  is closed, the mullion bar  62  is advanced into the guide block  80 , and the position sensor  160  generates an output signal. As described above, the piezoelectric gaskets  184  of the sensor  160  are compressed by the rib  186  as mullion bar  62  engages the plugs  170 . When the mullion bar  62  is seated in the guide block  80 , the electrical power generated by the piezoelectric gaskets  184  energizes the transmitter circuitry  190  such that the wireless data signal is transmitted. The controller  200  detects the signal from the sensor  160  and may use the signal to, for example, operate the power supply circuit  110 . 
     If the door  26  is not closed properly, the mullion bar  62  may not be fully positioned in the guide block  80  when the door  26  is closed. In such a case, no wireless signal is generated by the transmitter circuitry  190 . After the controller  200  receives the wireless signal from the door position sensor  122 , the controller may wait a predetermined amount of time to receive the wireless signal from the mullion position sensor  160 . If no signal is received, the controller  200  may generate an electrical output signal to activate an icon on the control panel  104  or energize the lighting devices  118  to indicate to the user that the mullion bar  62  is not properly positioned. 
     Referring to  FIG. 10 , a home appliance is shown as a dryer appliance  10 A (hereinafter dryer  10 A) for drying or tumbling laundry. The dryer  10 A includes a cabinet  12 A and a drum  14 A positioned in the cabinet  12 A. The drum  14 A is supported by a plurality of roller bearings  16 A, which permit the drum  14 A to rotate about a longitudinal axis  18 A relative to the cabinet  12 A. A chamber  20 A is defined in the drum  14 A and is sized to receive laundry. In use, laundry placed in the chamber  20 A is tumbled when the drum  14 A is rotated about the axis  18 A. 
     The cabinet  12 A has an access opening  22 A defined in a front panel  24 A, and the access opening  22 A is sized to permit user access to the drum chamber  20 A. A door  26 A is hinged to the front panel  24 A and is sized to cover the access opening  22 A. The door  26 A is moveable between the open position shown in  FIG. 10  in which user access to the opening  22 A is permitted and a closed position in which user access to the opening  22 A is prevented. It should be appreciated that in other embodiments the door  26 A may be a tiltable door rather than the swinging door shown in  FIG. 10 . The cabinet  12 A also includes a rear bulkhead  28 A that encloses the rear end of the chamber  20 A. Additionally, in other embodiments, the door  26 A may include a window that permits the user to see the chamber  20 A when the door  26 A is closed. 
     The dryer  10 A also includes a drive mechanism  30 A that is operable to rotate the drum  14 A about the axis  18 A, and an air system  32 A that is configured to advance heated air through the chamber  20 A of the drum  14 A to dry wet laundry contained in the drum  14 A. As shown in  FIG. 10 , the cabinet  12 A includes an upper console  34 A, and a control panel  36 A is attached to the console  34 A. The control panel  36 A includes a plurality of controls  38 A such as, for example, buttons, switches, knobs, or screens, which may be used to operate the various components of the dryer  10 A, including the drive mechanism  30 A and the air system  32 A, as described in greater detail below. 
     Referring now to  FIG. 11 , a number of the components of the dryer  10 A are shown in a simplified block diagram. The dryer  10 A includes a power supply circuit  50 A that is configured to supply electrical power to the electrical components of the dryer  10 A. The components of the power supply circuit  50 A may be located in any suitable portion of the dryer  10 A. It should be appreciated that the power supply circuit  50 A may include components, sub-components, and devices other than those shown in  FIG. 11 , which are not illustrated for clarity of the description. 
     As shown in  FIG. 11 , the power supply circuit  50 A may be electrically coupled to an AC mains power source  54 A, such as, for example, an electrical outlet commonly found in residential homes. The AC mains power source  54 A is electrically coupled to a DC power converter of the power supply circuit  50 A via a number of signal paths. These signal paths and other signal paths illustrated in  FIG. 11  may be embodied as any type of signal paths capable of communicating electrical signals between the components of the power supply circuit  50 A. For example, the signal paths may be embodied as any number of wires, cables, printed circuit board traces, bus, intervening devices, and/or the like. 
     The power supply circuit  50 A is electrically coupled to a number of the electrical components of the dryer  10 A. In the illustrative embodiment, the electrical components include a lighting device  56 A for illuminating the interior of the drum  14 A and an electronic control unit (ECU) or “electronic controller”  58 A, which is configured to control the operation of the dryer  10 A. The electrical components also include a battery  60 A and a number of components of the drive mechanism  30 A and the air system  32 A, as described in greater detail below. 
     The dryer  10 A also includes a piezoelectric power generator  62 A that is configured to generate electrical power when the door  26 A is moved between the closed position and the open position. In the illustrative embodiment, the generator  62 A is embodied as an array of piezoelectric film elements  64 A, as shown in  FIG. 10 . An exemplary film element is the LDT1-028K Piezo Sensor, which is commercially available from Seeed Studio of Shenzhen, China. Each element  64 A has a first end  66 A secured to the door  26 A and a second end  68 A secured to the front panel  24 A of the cabinet  12 A. It should be appreciated that the film elements  64 A may be formed from piezoelectric ceramics, such as, for example, lead zirconate titanate (PZT). In other embodiments, the piezoelectric elements may also be formed from an electroactive polymer (EAP) such as, for example, a stretchable dielectric elastomer. 
     When the door  26 A is opened, the piezoelectric film elements  64 A are bent as shown in  FIG. 10 . As the elements  64 A bend, the elements  64 A generate electrical power proportional to the degree of bending. The electrical power generated by the each element  64 A therefore increases as the door  26 A is moved to the open position. When the door  26 A is in the open position, the electrical power exceeds a predetermined quantity of power. In the illustrative embodiment, the predetermined quantity of power is approximately 1 Watt. It should be appreciated that in other embodiments the power may range from approximately 500 μW to 1 Watt. The elements  64 A of the generator  62 A are electrically connected to the power supply circuit  50 A such that power generated by the elements  64 A may be distributed to the other electrical components of the dryer  10 A, as described in greater detail below. 
     Referring to  FIGS. 11-12 , the drive mechanism  30 A of the dryer  10 A includes a belt  70 A that engages the drum  14 A, an electric motor  72 A that is configured to drive the belt  70 A to rotate the drum  14 A about the axis  18 A, and an idler assembly  74 A configured to tension the belt  70 A. As shown in  FIG. 12 , the motor  72 A is coupled to a motor support bracket  80 A that is attached to a base frame  82 A of the dryer  10 A. A plurality of wires  84 A connect the motor  72 A to the power supply circuit  50 A and permit electrical power to be supplied to the motor  72 A during operation. The motor  72 A has a drive shaft  86 A that supports a drive pulley  88 A such that when the motor  72 A is energized the drive pulley  88 A is rotated. It should be appreciated that the drive pulley  88 A may be integrally formed with the drive shaft  86 A or may be a separate component that is assembled with the drive shaft  86 A. 
     The drive pulley  88 A and the drum  14 A are connected via the belt  70 A, which wraps around the drive pulley  88 A and the drum  14 A. The belt  70 A also engages an idler pulley  90 A of the idler assembly  74 A, which presses against and thereby tensions the belt  70 A, as described in greater detail below. The idler assembly  74 A includes a support bracket  92 A that supports the idler pulley  90 A. In the illustrative embodiment, the idler pulley  90 A is coupled to the support bracket  92 A via a joint  94 A. As shown in  FIG. 12 , the joint  94 A includes a cylindrical pin  96 A that is received in bores  98 A defined in the idler pulley  90 A and an upper end  100 A of the support bracket  92 A. In that way, the joint  94 A permits the idler pulley  90 A to rotate. 
     The lower end of the support bracket  92 A is secured to the base frame  82 A of the dryer  10 A. As shown in  FIG. 12 , the bracket  92 A includes a spring support  104 A extending from the lower end and an upper support  106 A extending from the spring support  104 A to the upper end  100 A. The spring support  104 A is configured to exert a biasing force in the direction indicated by arrow  110 A to bias the idler pulley  90 A into engagement with the belt  70 A. 
     The spring support  104 A of the idler assembly  74 A includes a base  112 A extending from a free end  114 A to an end  116 A attached to a lever  118 A. A mounting tab  120 A and a peg  122 A extend from the base  112 A between the ends  114 A,  116 A. The tab  120 A and the peg  122 A are received in slots defined in the base frame  82 A of the dryer  10 A to secure the support  104 A to the base frame  82 A. As shown in  FIG. 12 , the lever  118 A extends upwardly from the base  112 A to an upper end  128 A that is secured to the upper support  106 A. 
     The lever  118 A cooperates with the base  112 A to define a substantially V-shape of the spring support  104 A. A distance  130 A is defined between the upper end  128 A of the lever  118 A and the base frame  82 A. The spring support  104 A is designed to have a thickness and bending resistance to resist an expansion of its V-shape (and hence an increase in the distance  130 A) during operation of the dryer  10 A. In that way, the support  104 A provides the biasing force in the direction indicated by arrow  110 A to bias the idler pulley  90 A into engagement with the belt  70 A. 
     In the illustrative embodiment, the support  104 A is formed from a metallic material such as, for example, stainless steel. It should be appreciated that in other embodiments the support  104 A may be formed from a polymer material. Additionally, in other embodiments, the idler assembly  74 A may include a helical spring, compression spring, or other type of biasing element to bias the idler pulley  90 A into engagement with the belt  70 A. 
     When the motor  72 A is energized, the drive shaft  86 A and the drive pulley  88 A are rotated in the direction indicated by curved arrow  132 A in  FIG. 12 . As the drive pulley  88 A is rotated, the belt  70 A is advanced along the drive pulley  88 A, the idler pulley  90 A, and the drum  14 A, thereby causing the idler pulley  90 A and the drum  14 A to rotate. The tension on the belt  70 A changes as the drum  14 A is rotated, and that change in the tension, along with circular run out of the outer diameter of the drum  14 A, exerts a force on the idler pulley  90 A in the direction opposite the arrow  110 A. During operation, the force on the idler pulley  90 A is continuously varied as the drum  14 A is rotated. When the force on the idler pulley  90 A exceeds the biasing force of the support  104 A, the lever  118 A is moved in the direction indicated by arrow  134 A, thereby causing the distance  130 A between the upper end  128 A of the lever  118 A and the base  112 A to increase. Because the amount of force on the idler pulley  90 A is continuously varied as the drum  14 A is rotated, the distance  130 A defined between the upper end  128 A of the lever  118 A and the base  112 A is also continuously varied. 
     As shown in  FIGS. 11-12 , the dryer  10 A includes a drive sensor  140 A to provide an indication of the status of the drive mechanism  30 A. The sensor  140 A includes a piezoelectric power generator  142 A that is configured to generate electrical power when the drum  14 A is rotated. In the illustrative embodiment, the generator  142 A is formed from an electroactive polymer (EAP) such as, for example, a stretchable dielectric elastomer, which generates electrical power when deformed. In other embodiments, the generator  142 A may be formed as a spring or disk from a piezoelectric ceramic, such as, for example, lead zirconate titanate (PZT). 
     As shown in  FIG. 12 , the generator  142 A has an upper end  146 A secured to the upper end  128 A of the lever  118 A and a lower end  148 A secured to the base frame  82 A. The generator  142 A has an initial length  150 A, which is equal to the distance  130 A, when the dryer  10 A is not operated. When the lever  118 A is moved in the direction indicated by arrow  134 A by the rotation of the drum  14 A, the generator  142 A is stretched to an increased length that is approximately 0.125 inches greater than the initial length  150 A. In other embodiments, the generator  142 A may deform by a greater or lesser amount. As the generator  142 A is stretched, the generator  142 A generates electrical power proportional to the amount of deformation. The continuous movement of the lever  118 A thereby causes the generator  142 A to move back and forth between its initial length and its stretched length. In the illustrative embodiment, the generator  142 A is configured to generate an average quantity of power equal to approximately 1 Watt. It should be appreciated that in other embodiments the power may range from approximately 500 μW to 1 Watt. 
     The piezoelectric generator  142 A is electrically connected to transmitter circuitry  160 A. The transmitter circuitry  160 A is configured to transmit a wireless data signal when energized. In the illustrative embodiment, the transmitter circuitry  160 A uses a Bluetooth transmission protocol. The electrical power generated by the generator  142 A energizes the transmitter circuitry  160 A such that the wireless data signal is transmitted. In that way, the drive sensor  140 A does not require power from the power supply circuit  50 A (and hence the AC mains power source  54 A). 
     When the dryer  10 A is in operation, the transmitter circuitry  160 A is energized by the generator  142 A and generates the wireless data signal. If, for example, the belt  70 A is broken or if the drive mechanism  30 A has another fault that permits the motor  72 A from rotating, the lever  118 A would not move and no power would be generated by the generator  142 A. As a result, the transmitter circuitry  160 A would be de-energized. In that way, the sensor  140 A provides an indication of the status of the drive mechanism  30 A. 
     In other embodiments, the transmitter circuitry  160 A may be configured to transmit via a local area network, infrared communication, or other wireless communication protocol. It should also be appreciated that in other embodiments the transmitter circuitry  160 A may be replaced with a Radio-Frequency Identification (RFID) tag. When the generator  142 A is generating electrical power, the RFID tag may be energized to transmit a wireless signal. 
     As shown in  FIG. 11 , the dryer  10 A includes a wireless receiver  162 A that is configured to receive the data signals generated by the drive sensor  140 A. In the illustrative embodiment, the receiver  162 A is configured to use the Bluetooth transmission protocol. It should be appreciated that the receiver  162 A may be embodied as any type of wireless receiver capable of receiving the data signals from the sensor  140 A. For example, the wireless receiver may be embodied as a wireless router. The wireless receiver  162 A is communicatively coupled the electronic controller  58 A via a number of communication links  164 A such as wires, cables, or the like. 
     As described above, the dryer  10 A also includes an air system  32 A that is configured to advance heated air through the chamber  20 A of the drum  14 A to dry the wet laundry as it is tumbled by drum  14 A. In the illustrative embodiment, the air system  32 A is a negative pressure or vacuum system by which a motor driven blower  170 A draws air into a heating duct  172 A, through the chamber  20 A, and into an exit duct  174 A before the air is discharged from the dryer  10 A. The air system  32 A also includes an electric heating element  176 A that is positioned in the duct  172 A and is configured to heat the air passing through the duct  172 A. The blower  170 A and the heating element  176 A are electrically coupled to the power supply circuit  50 A, which supplies power to the blower  170 A and the element  176 A during operation. It should be appreciated that in other embodiments the dryer  10 A may include a gas-fired burner or heater to heat the air in the duct  172 A. 
     The heating duct  172 A of the system  32 A includes an inlet opening  180 A defined in a rear panel  182 A of the cabinet  12 A and an outlet grill or opening  178 A that is defined in the bulkhead  28 A (see  FIG. 10 ). Air heated by the heating element  176 A may advance through the grill  178 A into the chamber  20 A of the drum  14 A. 
     As shown in  FIGS. 13-14 , the cabinet  12 A includes a forward bulkhead  190 A that is positioned below the access opening  22 A. The forward bulkhead  190 A includes an upper surface  192 A and an inner side wall  194 A that extends downwardly from the upper surface  192 A. An exit grill  196 A is defined in the inner side wall  194 A. As shown in  FIG. 13 , the exit grill  196 A includes a plurality of openings  198 A that connect the chamber  20 A of the drum  14 A with a chute  200 A of the exit duct  174 A. 
     The upper surface  192 A of the forward bulkhead  190 A has a slot  202 A defined therein. The slot  202 A is rectangular and opens into the chute  200 A. The chute  200 A and the slot  202 A are sized to receive a filter  204 A. The filter  204 A includes a handle  206 A configured to be positioned in the slot  202 A and a screen  208 A, which is positioned over the openings  198 A of the exit grill  196 A when the handle  206 A is positioned in the slot  202 A. Air advanced through the openings  198 A is passed through the screen  208 A, which is configured to trap or catch lint and other particulates carried by the air to prevent their passage into the remainder of the exit duct  174 A and hence the blower  170 A. As shown in  FIGS. 13 and 14 , the filter  204 A may be removed from the chute  200 A and the slot  202 A for cleaning. 
     As shown in  FIG. 14 , another opening  210 A is defined in the upper surface  192 A of the forward bulkhead  190 A adjacent to the slot  202 A. A number of inner walls  212 A extend downwardly from the opening  210 A to define a passageway  214 A of the exit duct  174 A. As shown in  FIG. 13 , the upper end  216 A of the passageway  214 A is isolated from the chute  200 A by the inner walls  212 A. The lower end  218 A of the passageway  214 A merges with the chute  200 A to form a main passageway  220 A of the exit duct  174 A. The passageway  214 A is sized such that a fraction of the air circulating in the chamber  20 A of the drum  14 A advances through the passageway  214 A. The remaining air is advanced through the openings  198 A of the exit grill  196 A and into the screen  208 A of the filter  204 A during normal operation. In the illustrative embodiment, a flow sensor  222 A is positioned in upper end  216 A of the passageway  214 A. 
     As shown in  FIG. 15 , the flow sensor  222 A includes a base  224 A secured to one of the inner walls  212 A defining the passageway  214 A and a cantilevered arm  226 A extending outwardly from the base  224 A. The flow sensor  222 A also includes a piezoelectric power generator  230 A, which extends over the cantilevered arm  226 A and is configured to generate power when air is advanced through the passageway  214 A. In the illustrative embodiment, the generator  230 A is embodied as a piezoelectric film element. An exemplary film element is the LDT1-028K Piezo Sensor, which is commercially available from Seeed Studio of Shenzhen, China. It should be appreciated that the film element may be formed from a piezoelectric ceramic, such as, for example, lead zirconate titanate (PZT). In other embodiments, the piezoelectric element may also be formed from an electroactive polymer (EAP) such as, for example, a stretchable dielectric elastomer. 
     When air is advanced through the passageway  214 A, the force of the air flow causes the cantilevered arm  226 A to deflect. The amount of deflection is proportional to the force of the air flow. When the cantilevered arm  226 A is deflected, the generator  230 A is bent, thereby causing the generator  230 A to generate power. As described above, a piezoelectric film generator  230 A generates electrical power proportional to the degree of bending; as such, the amount of electrical power generated by the generator  230 A is proportional to the amount of deflection of the arm  226 A and hence the force of the air flowing through the passageway  214 A. The piezoelectric generator  230 A is electrically connected to electronic controller  58 A, which may adjust the operation of the dryer  10 A based on the amount of electrical power generated by the generator  230 A, as described in greater detail below. It should be appreciated that in other embodiments the generator  230 A may be connected to the controller  58 A via wireless circuitry. 
     The electronic controller  58 A of the dryer  10 A is positioned in the cabinet  12 A. The electronic controller  58 A is, in essence, the master computer responsible for interpreting electrical signals sent by sensors associated with the dryer  10 A and for activating or energizing electronically-controlled components associated with the dryer  10 A. For example, the electronic controller  58 A is configured to control operation of the various components of the dryer  10 A, including the lighting device  56 A, heating element  176 A, blower  170 A, motor  72 A, and the operation of the power circuit  50 A. The electronic controller  58 A also monitors various signals from the control panel  36 A, the drive sensor  140 A, the flow sensor  222 A, and any other sensor. The electronic controller  58 A also determines when various operations of the dryer  10 A should be performed. As will be described in more detail below, the electronic controller  58 A is operable to control the components of the dryer  10 A such that the dryer  10 A solicits user input regarding dryer performance and adjusts operational parameters of the dryer  10 A in response thereto. 
     To do so, the electronic controller  58 A includes a number of electronic components commonly associated with electronic units utilized in the control of electromechanical systems. For example, the electronic controller  58 A may include, amongst other components customarily included in such devices, a processor such as a microprocessor  240 A and a memory device  242 A such as a programmable read-only memory device (“PROM”) including erasable PROM&#39;s (EPROM&#39;s or EEPROM&#39;s). The memory device  242 A is provided to store, amongst other things, instructions in the form of, for example, a software routine (or routines) which, when executed by the microprocessor  240 A, allows the electronic controller  58 A to control operation of the dryer  10 A. 
     The electronic controller  58 A also includes an analog interface circuit  244 A. The analog interface circuit  244 A converts the output signals from the receiver  162 A into signals which are suitable for presentation to an input of the microprocessor  240 A. In particular, the analog interface circuit  244 A, by use of an analog-to-digital (A/D) converter (not shown) or the like, converts the analog signals generated by the sensors into digital signals for use by the microprocessor  240 A. It should be appreciated that the A/D converter may be embodied as a discrete device or number of devices, or may be integrated into the microprocessor  240 A. It should also be appreciated that if any one or more of the sensors associated with the dryer  10 A generate a digital output signal, the analog interface circuit  244 A may be bypassed. 
     Similarly, the analog interface circuit  244 A converts signals from the microprocessor  240 A into output signals which are suitable for presentation to the electrically-controlled components associated with the dryer  10 A (e.g., the lighting device  56 A). In particular, the analog interface circuit  244 A, by use of a digital-to-analog (D/A) converter (not shown) or the like, converts the digital signals generated by the microprocessor  240 A into analog signals for use by the electronically-controlled components associated with the dryer  10 A. It should be appreciated that, similar to the A/D converter described above, the D/A converter may be embodied as a discrete device or number of devices, or may be integrated into the microprocessor  240 A. It should also be appreciated that if any one or more of the electronically-controlled components associated with the dryer  10 A operate on a digital input signal, the analog interface circuit  244 A may be bypassed. 
     Thus, the electronic controller  58 A may control the operation of the dryer  10 A. In particular, the electronic controller  58 A executes a routine including, amongst other things, a control scheme in which the electronic controller  58 A monitors the outputs of the sensors associated with the dryer  10 A, including the drive sensor  140 A and the flow sensor  222 A, to control the inputs to the electronically-controlled components associated therewith. To do so, the electronic controller  58 A communicates with the sensors directly or indirectly through the wireless receiver  162 A to determine, amongst numerous other things, the state of the drive mechanism  30 A and the air system  32 A. Armed with this data, the electronic controller  58 A performs numerous calculations, either continuously or intermittently, including looking up values in preprogrammed tables, in order to execute algorithms to perform such functions as energizing the electric motor  72 A, energizing the heating element  176 A, energizing the blower  170 A, activating an indicator on the control panel  36 A, and so on. 
     In use, a user may open the door  26 A to place wet laundry in the drum chamber  20 A or remove dry laundry therefrom. As described above, the power generator  62 A is operable to generate electrical power when the door  26 A is opened. As the door  26 A is opened, the film elements  64 A of the generator  62 A bend and generate electrical power proportional to the degree of bending. As described above, the electrical power generated by the generator  62 A is transferred to the power supply circuit  50 A. The controller  58 A may detect the power generation via the power supply circuit  50 A and determine that the door  26 A is open. In other embodiments, the dryer  10 A may also include a door position sensor that generates a signal when the door  26 A is opened. 
     When the controller  58 A determines the door  26 A is opened, the controller  58 A may generate an electrical output signal to operate the power supply circuit  50 A. In response to the receiving the signal from the controller  58 A, the circuit  50 A supplies power to, for example, the lighting device  56 A to illuminate the chamber  20 A. The power supply circuit  50 A may direct the electrical power supplied by the generator  62 A to energize the lighting device  56 A or to the battery  60 A for storage. Additionally, or alternatively, the power supply circuit  50 A may supply power from the ac mains power source  54 A to energize the lighting device  56 A. 
     When the door  26 A is closed, the power generated by the electrical power generator  62 A decreases to approximately zero. The controller  58 A may detect this loss of power and generate an electrical output signal to operate the power supply circuit  50 A to, for example, deenergize the lighting device  56 A. 
     The user may utilize the control panel  36 A to select a laundry cycle and activate the dryer  10 A. In response to a user input from the control panel  36 A, the controller  58 A may operate the various electrical components of the dryer  10 A to execute the cycle. The controller  58 A may operate the power supply circuit  50 A to energize the motor  72 A, the blower  170 A, and the heating element  176 A. As described above, when the motor  72 A is energized, the drive shaft  86 A and the drive pulley  88 A are rotated in the direction indicated by curved arrow  132 A. As the drive pulley  88 A is rotated, the belt  70 A is advanced along the drive pulley  88 A, the idler pulley  90 A, and the drum  14 A, thereby causing the idler pulley  90 A and the drum  14 A to rotate. 
     As described above, the tension on the belt  70 A changes as the drum  14 A is rotated, and that change in the tension, along with circular run out of the outer diameter of the drum  14 A, exerts a force on the idler pulley  90 A. When the force on the idler pulley  90 A exceeds the biasing force of the support  104 A, the lever  118 A is moved in the direction indicated by arrow  134 A in  FIG. 12 , thereby causing the distance  130 A between the upper end  128 A of the lever  118 A and the base  112 A to increase. As described above, the movement of the lever  118 A causes the generator  142 A of the sensor  140 A to stretch and generate electrical power in proportion thereto. The continuous movement of the lever  118 A thereby causes the generator  142 A to move back and forth between its initial length and its stretched length such that an average amount of power is generated. The power generated by generator  142 A energizes the transmitter circuitry  160 A, which generates a wireless data signal. 
     The sensor  140 A further provides an indication when the drive mechanism  30 A experiences a fault. For example, if the belt  70 A were to break, the movement of the lever  118 A would cease. As a result, the generator  142 A would not generate electrical power, and no wireless data signal would be generated. Similarly, no signal would be generated if the motor  72 A experienced a fault that impaired its ability to rotate the drum  14 A. 
     The controller  58 A monitors the output of the sensor  140 A. If the controller  58 A detects the wireless data signal, the controller  58 A may continue to operate the dryer  10 A according to the selected cycle. If, however, the wireless data signal is not generated or received, the controller  58 A may operate the power supply circuit  50 A to de-energize the electrical components of the dryer  10 A. The controller  58 A may also activate an indicator on the control panel  36 A to provide an indication of the fault to the user. 
     As described above, the dryer  10 A also includes a flow sensor  222 A that is positioned in the duct  174 A of the air system  32 A. When the dryer  10 A is executing a cycle, the blower  170 A draws air into the heating duct  172 A to be heated by the heating element  176 A. Heated air may then be advanced into the drum chamber  20 A, where it is circulated into contact with the laundry contained therein. Air may then be drawn into the exit duct  174 A through the chute  200 A and the passageway  214 A. The flow sensor  222 A is configured to generate electrical power based on the amount of air flowing through the passageway  214 A. 
     As shown in  FIG. 15 , when no air is advanced through the passageway  214 A, the cantilevered arm  226 A of the sensor  222 A is in an undeflected position  250 A and the generator  230 A of the sensor  222 A generates no power. In normal operation, when the filter  204 A is positioned in the chute  200 A and the screen  208 A is substantially free of particulates, approximately five to ten percent of the air circulating in the chamber  20 A of the drum  14 A advances through the passageway  214 A, and the cantilevered arm  226 A is deflected to a degree of deflection  252 A. In that position, the generator  230 A generates a quantity of electrical power that indicates the degree of deflection  252 A and hence the amount of air flowing through the passageway  214 A. 
     As the screen  208 A is covered by lint and other particulates during operation, the amount of air passing into the chute  200 A is decreased and additional air is advanced into the passageway  214 A. When the screen  208 A is substantially covered by lint, the cantilevered arm  226 A is deflected to another degree of deflection  254 A. In that position, the generator  230 A generates a quantity of electrical power that indicates the degree of deflection  254 A and hence the amount of air flowing through the passageway  214 A. 
     If the filter  204 A is removed from chute  200 A and the dryer  10 A is activated, the amount of air passing into the chute  200 A is not restricted by the screen  208 A and is increased. As a result, the amount of air advancing through the passageway  214 A is decreased, and the cantilevered arm  226 A may be deflected to a degree of deflection  256 A that is less than the degrees of deflection  252 A,  254 A. In that position, the generator  230 A generates a quantity of electrical power that indicates the degree of deflection  256 A and hence the amount of air flowing through the passageway  214 A. 
     The controller  58 A monitors the output of the sensor  222 A. If the electrical power output of the sensor  222 A is approximately equal to a predetermined amount, thereby indicating the degree of deflection  252 A, the controller  58 A may continue to operate the dryer  10 A according to the selected cycle. If, however, the output of the sensor  222 A is greater than a predetermined amount, thereby indicating the deflection  254 A, or less than a predetermined amount, thereby indicating the deflection  256 A, the controller  58 A may operate the power supply circuit  50 A to de-energize the electrical components of the dryer  10 A. The controller  58 A may also activate an indicator on the control panel  36 A to provide an indication of the fault to the user. 
     It should be appreciated that the concepts illustrated above may be applied to other aspects of the operation of an appliance. For example, the output of the drive sensor  140 A may be used by the controller  58 A to provide an indication of belt tension and thus the load present in the drum  14 A. Because the power required to rotate the drum  14 A is a function of the weight of the load (and hence a function of the amount of water in the laundry), the controller  58 A may utilize the indication of the load to estimate the remaining dry time and adjust the operation of the dryer. Additionally, the controller  58 A may be configured to monitor the output of the drive sensor  140 A when the dryer  10 A is off to determine if something is in the drum  14 A. If movement is detected (i.e., the drive sensor  140 A generates an output signal), the controller  58 A may be configured to provide an indication to the user via the control panel  36 A or otherwise disable the dryer  10 A until the fault is cleared by the user. 
     Referring now to  FIGS. 16 and 17 , another embodiment of a dryer (hereinafter dryer appliance  310 A) is shown. The dryer  310 A is similar to that discussed above with regard to  FIGS. 10-15 . For ease of description, those structures in  FIGS. 16 and 17  that are substantially identical to the structures shown and described above in regard to  FIGS. 10-15  are identified with the same reference numbers. As shown in  FIG. 16 , the dryer  310 A includes a cabinet  12 A and a drum  14  positioned in the cabinet  12 A. The drum  14 A is supported by a plurality of roller bearings  16 A, which permit the drum  14 A to rotate relative to the cabinet  12 A. A chamber  20 A is defined in the drum  14 A and is sized to receive laundry. In use, laundry placed in the chamber  20 A is tumbled when the drum  14 A is rotated. 
     The cabinet  12 A has an access opening  22 A defined in a front panel  24 A, and the access opening  22 A is sized to permit user access to the drum chamber  20 A. A door  312 A is hinged to the front panel  24 A and is sized to cover the access opening  22 A. The door  312 A is moveable between the open position shown in  FIG. 16  in which user access to the opening  22 A is permitted and a closed position in which user access to the opening  22 A is prevented. As shown in  FIG. 16 , the door  312 A includes a window  314 A that permits the user to see the chamber  20 A when the door  312 A is closed. In the illustrative embodiment, the window  314 A is formed from glass. It should be appreciated that in other embodiments the window  314 A may be formed a clear plastic material. 
     The dryer  310 A also includes a drive mechanism  30 A that is operable to rotate the drum  14 A. As shown in  FIG. 16 , the drum  14 A includes a number of baffles  320 A. Each baffle  320 A is configured to tumble laundry and other contents of the chamber  20 A when the drum  14 A is rotated by the drive mechanism  30 A. The baffles  320 A may be any shape (e.g., blade-shaped or paddle-shaped) suitable for tumbling the laundry. 
     In the embodiment of  FIGS. 16 and 17 , the dryer  310 A includes a plurality of piezoelectric power generators  322 A and a plurality of light sources  324 A that are positioned in the chamber  20 A. Each light source  324 A is secured to the drum  14 A and configured to rotate therewith. In other embodiments, one or more of the light sources  324 A may be secured to the power generator  322 A. Each piezoelectric power generator  322 A is secured to the drum  14 A and is configured to provide power to the light sources  324 A. In the illustrative embodiment, the generators  322 A are the exclusive power supplies on the drum  14 A such that the light sources  324 A do not require power from the power supply circuit (not shown) and hence the AC mains power source. 
     Each generator  322 A includes an elongated arm  326 A that extends from a baffle  320 A. As shown in  FIG. 17 , each arm  326 A is cantilevered and has a piezoelectric film element  328 A positioned thereon. An exemplary film element  328 A is the LDT1-028K Piezo Sensor, which is commercially available from Seeed Studio of Shenzhen, China. It should be appreciated that the film element may be formed from a piezoelectric ceramic, such as, for example, lead zirconate titanate (PZT). In other embodiments, the piezoelectric element may also be formed from an electroactive polymer (EAP) such as, for example, a stretchable dielectric elastomer. 
     When the cantilevered arm  326 A is deflected, the corresponding film element  328 A is bent, thereby causing the generator  322 A to produce power. The piezoelectric film element  328 A generates electrical power proportional to the degree of bending; as such, the amount of electrical power generated by the film element  328 A is proportional to the amount of deflection of the arm  326 A. In the illustrative embodiment, each film element  328 A may produce power in the range of approximately 500 μW to 1 Watt. It should be appreciated that the generators  322 A may be otherwise shaped and/or coupled to the drum  14 A in other embodiments. 
     The power produced by the generators  322 A is supplied to one or more light sources  324 A via cable harness  330 A. In the illustrative embodiment, each light source  324 A is a light emitting diode (LED) operable to product light when energized. It should be appreciated that in other embodiments other sources of light may be used. When energized, each LED is visible through the window  314 A of the door  312 A. It should be appreciated the LEDs may be arranged in a pattern or aesthetic arrangement on the drum  14 A. 
     During operation, laundry is tumbled in the drum  14 A, and the laundry impacts the cantilevered arms  326 A extending from the baffles  320 A. The force of the impact of the laundry causes the cantilevered arms  326 A (and hence the piezoelectric element  328 A) to deflect, thereby causing the generator  322 A to supply power to the LEDs  324 A. The light created by the LEDs  324 A is visible through the window  314 A to provide a visual indication of the rotation of the drum  14 A. 
     In other embodiments, the generators  322 A may be used to power other devices on drum  14 A. Additionally, it should be appreciated that in other embodiments one or more of the light sources may be powered through inductance by placing the power source or primary inductor on the cabinet of the dryer. A secondary inductor may be included on the drum to power the light source. 
     As described above, the dryer includes a number of roller bearing  16 A that support the drum  14 A. As the drum  14 A is rotated during operation, the load on each bearing  16 A varies with the movement of the load in the drum  14 A. That variation in movement may cause flexing. A piezoelectric device similar to those described above may be mounted between the drum  14 A and the cabinet  12 A to generate electrical power from the flexing. 
     A piezoelectric device may also be secured to the dryer feet, which engage the floor and support the dryer  10 A. The piezoelectric device would be configured to generate power from the vibration transmitted to the floor. Another piezoelectric device may be integrated into a sensor ball, which is introduced into the drum during operation. The sensor may be charged by tumbling action and used to transmit a wireless signal to the controller. The sensor ball would monitor the dryness levels of the clothes and the acceleration of the ball, which would provide feedback on the tumbling pattern of the clothes and the load size. With that data, the controller could, for example, adjust the rotational speed of the drum to optimize drying. The sensor ball may also be configured to detect differences in gas content to detect fire or combustion. 
     Although the concepts are described herein with regard to an electric dryer, the concepts described herein may be applied to gas dryers in other embodiments. Additionally, the concepts described herein may be applied to other domestic appliances, such as, for example, a washer for laundry. 
     Referring to  FIGS. 18-19 , a home appliance is shown as a washer appliance  10 B (hereinafter washer  10 B) for washing laundry. The washer  10 B includes a cabinet  12 B and a tub  14 B positioned in the cabinet  12 B. As shown in  FIG. 19 , the tub  14 B is supported within the cabinet  12 B by one or more dampers  16 B and/or other support structure. The tub  14 B includes a chamber or cavity  18 B configured to contain a washing fluid for washing the laundry; as described in greater detail below, the cavity  18 B is configured to receive washing fluid from an external fluid supply during a wash cycle and drain the fluid upon completion. 
     A rotating drum  20 B is positioned in the cavity  18 B of the tub  14 B, as shown in  FIG. 18 . The drum  20 B is configured to rotate about a longitudinal axis  22 B relative to the tub  14 B and therefore the cabinet  12 B. A chamber  24 B is defined in the drum  20 B and is sized to receive laundry to be washed. In the illustrative embodiment, the drum  20 B includes a number of baffles  26 B. Each baffle  26 B is configured to tumble laundry and other contents of the chamber  24 B when the drum  20 B is rotated about the axis  22 B. The baffles  26 B may be any shape (e.g., blade-shaped or paddle-shaped) suitable for tumbling the laundry. 
     The tub  14 B of the washer  10 B includes an access portal  30 B that is defined in a front side  32 B thereof. The cabinet  12 B has an access opening  34 B that is defined in a front panel  36 B and is aligned with the portal  30 B of the tub  14 B. The opening  34 B and the portal  30 B are sized to permit user access to the drum chamber  24 B. A door  38 B is hinged to the front panel  36 B and is sized to cover the access opening  34 B of the cabinet  12 B. The door  38 B is moveable between the open position shown in  FIG. 18  in which user access to the opening  34 B is permitted and a closed position in which user access to the opening  34 B is prevented. It should be appreciated that in other embodiments the door  38 B may be a tiltable door rather than the swinging door shown in  FIG. 18 . 
     As shown in  FIG. 19 , an annular seal  40 B extends between the front side  32 B of the tub  14 B and an inner wall  42 B of the cabinet  12 B. The annular seal  40 B encircles the rear edge of the access opening  34 B and the access portal  30 B of the tub  14 B, thereby preventing leakage of wash fluid. In the illustrative embodiment, the annular seal  40 B is a bellows that has an S-shaped cross-section and is formed from an elastomeric material such as, for example, rubber or plastic. It should be appreciated that in other embodiments the seal may be an o-ring seal, gasket, or other structure capable of preventing fluid leakage. During operation, the annular seal  40 B stretches or flexes with the movement of the tub  14 B, as described in greater detail below. 
     The washer  10 B also includes a drive mechanism  44 B that is operable to rotate the drum  20 B about the axis  22 B. In the illustrative embodiment, the drive mechanism  44 B is attached to the tub  14 B and includes a motor and a driveshaft that engages the drum  20 B. An exemplary drive mechanism is shown and described in U.S. Patent App. Pub. No. 2010/0307202 entitled “WASHING MACHINE WITH A DIRECT DRIVE SYSTEM,” which is expressly incorporated herein by reference. It should be appreciated that in other embodiments the drive mechanism may be secured to the cabinet and may be configured to rotate the drum  20 B through a drive belt or other transmission. The washer  10 B has a control panel  46 B that may be utilized to operate the drive mechanism  44 B. As shown in  FIG. 18 , the control panel  46 B is positioned on the front panel  36 B of the cabinet  12 B above the access opening  34 B. A plurality of controls  48 B are included on the panel  46 B such as, for example, buttons, switches, knobs, or screens, which may be used to operate the drive mechanism  44 B and the other components of the washer  10 B. 
     As described above, the tub  14 B is supported by a number of dampers  16 B. As shown in  FIG. 19 , each damper  16 B includes an outer cylinder  50 B attached to the cabinet  12 B and a rod  52 B that extends outwardly from the cylinder  50 B and is secured to the tub  14 B. In the illustrative embodiment, the rod  52 B of the damper  16 B is configured to move into and out of the cylinder  50 B to damp vibration that is generated during operation of the washer  10 B. An exemplary damper is the Washer Damper Shock Absorber Model No. 34001292, which is commercially available from Whirlpool Corporation of Benton Harbor, Mich. 
     Referring now to  FIG. 20 , a number of the components of the washer  10 B are shown in a simplified block diagram. The washer  10 B in the illustrative embodiment includes an electronic control unit (ECU) or “electronic controller”  60 B, which is configured to control the operation of the washer  10 B and a power supply circuit or circuitry  62 B that is configured to supply electrical power to the other electrical components  64 B of the washer  10 B. It should be appreciated that the power supply circuit  62 B may include components, sub-components, and devices other than those shown in  FIG. 20 , which are not illustrated for clarity of the description. 
     As shown in  FIG. 20 , the power supply circuitry  62 B may be electrically coupled to an AC mains power source  56 B, such as, for example, an electrical outlet commonly found in residential homes. The AC mains power source  56 B is electrically coupled to a DC power converter of the power supply circuitry  62 B via a number of signal paths. These signal paths and other signal paths illustrated in  FIG. 20  may be embodied as any type of signal paths capable of communicating electrical signals between the components of the power supply circuitry  62 B. For example, the signal paths may be embodied as any number of wires, cables, printed circuit board traces, bus, intervening devices, and/or the like. It should be appreciated, however, that some signal paths have been omitted from  FIG. 20  for clarity. 
     As described above, the power supply circuitry  62 B is electrically coupled to a number of the electrical components  64 B of the washer  10 B. The electrical components  64 B may include any number of electrical and/or electro-mechanical components such as those commonly found in a laundry appliance. For example, in the illustrative embodiment, the electrical components  64 B include the drive mechanism  44 B and the controller  60 B. The electrical components  64 B also include a heating element  68 B that is configured to heat wash fluid supplied to the tub  14 B from an external fluid supply  70 B and a battery  72 B. The washer  10 B may also include various sensors such as, for example, proximity sensors, optical sensors, light sensors, audio sensors, temperature sensors, thermistors, motion sensors, piezoelectric sensors, mold and biological film sensors, and/or other types of sensors. Further, the washer  10 B may also include components and/or devices configured to facilitate the use of the sensors. 
     As shown in  FIGS. 19 and 20 , the washer  10 B includes a damper sensor  80 B that is secured to one of the dampers  16 B. The sensor  80 B includes a piezoelectric power generator  82 B that is configured to generate electrical power when the drum  20 B is rotated and hence the damper rod  52 B is moved relative to the cylinder  50 B. In the illustrative embodiment, the generator  82 B is formed from an electroactive polymer (EAP) such as, for example, a stretchable dielectric elastomer, which generates electrical power when deformed. In other embodiments, the generator  82 B may be formed as a spring or disk from a piezoelectric ceramic, such as, for example, lead zirconate titanate (PZT). 
     As shown in  FIG. 19 , the generator  82 B has an upper end  84 B secured to the damper rod  52 B and a lower end  86 B secured to the cylinder  50 B of the damper  16 B. When the damper rod  52 B is moved out of the cylinder  50 B by the motion of the tub  14 B, the generator  82 B is stretched. As the generator  82 B is stretched, the generator  82 B generates electrical power proportional to the amount of deformation. The continuous movement of the damper rod  52 B thereby causes the generator  82 B to move back and forth between its initial length and its stretched length. The electrical power produced by the generator  82 B is supplied to the controller  60 B in the form of an electrical signal, which the controller  60 B may use to determine the operating frequency of the damper  16 B and hence the tub  14 B, as described in greater detail below. 
     As shown in  FIGS. 19 and 20 , the washer  10 B also includes a seal sensor  90 B. In the illustrative embodiment, the seal sensor  90 B includes a mold detector  92 B configured to detect the odor or chemical composition of mold or other biological films on the annular seal  40 B. Examples of a mold detector include the CanarIT sensor, which is commercially available from Air Base Systems of Israel, and the sensors shown and described in International Patent App. Pub. No. WO2012/121229 entitled “MICROORGANISM DETECTION SENSOR AND PROCESS FOR MANUFACTURING SAME,” which is expressly incorporated herein by reference. 
     The seal sensor  90 B also includes a piezoelectric power generator  94 B that is secured to the annular seal  40 B. In the illustrative embodiment, the generator  94 B includes an array of piezoelectric elements  96 B that are attached around the perimeter of the annular seal  40 B. As described above, the annular seal  40 B flexes and/or stretches during operation of the washer  10 B, and each piezoelectric element  96 B is configured to generate power when the annular seal  40 B is stretched or flexed. In the illustrative embodiment, each piezoelectric element  96 B is formed from a piezoelectric ceramic, such as, for example, lead zirconate titanate (PZT), which flexes or bends with the annular seal  40 B to generate electrical power. It should be appreciated that in other embodiments the piezoelectric element may also be formed from an electroactive polymer (EAP) such as, for example, a stretchable dielectric elastomer, which generates electrical power when deformed. 
     As each piezoelectric element  96 B is stretched, the generator  94 B generates electrical power proportional to the amount of deformation. The continuous flexing and stretching of the annular seal  40 B thereby causes the piezoelectric elements  96 B to stretch and contract. In the illustrative embodiment, the generator  94 B is configured to generate an average quantity of power equal to approximately 1 Watt. It should be appreciated that in other embodiments the power may range from approximately 500 μW to 1 Watt. 
     The generator  94 B is electrically coupled to the detector  92 B of the seal sensor  90 B and provides the electrical power necessary for the detector  92 B to operate. In the illustrative embodiment, the detector  92 B is electrically coupled to the electronic controller  60 B. The detector  92 B is configured to generate an electrical output signal indicative of the presence of mold when powered by the piezoelectric generator  94 B. As described in greater detail below, the controller  60 B is configured to adjust the operation of the washer  10 B based on the signal from the detector  92 B. For example, the controller  60 B may alert a user of the washer  10 B about the presence of mold by, for example, flashing a light on the control panel  46 B of the washer  10 B. It should be appreciated that in other embodiments the seal sensor  90 B may include a wireless transmitter to relay the electrical output signal to the controller  60 B. 
     The electronic controller  60 B of the washer  10 B is positioned in the cabinet  12 B. The electronic controller  60 B is, in essence, the master computer responsible for interpreting electrical signals sent by sensors associated with the washer  10 B and for activating or energizing electronically-controlled components associated with the washer  10 B. For example, the electronic controller  60 B is configured to control operation of the various components of the washer  10 B, including the drive mechanism  44 B, the heating element  68 B, and the operation of the power circuit  62 B. The electronic controller  60 B also monitors various signals from the control panel  46 B, the damper sensor  80 B, the seal sensor  90 B, and the sensors associated with the active balancing system  100 B, which are described in greater detail below. The electronic controller  60 B also determines when various operations of the washer  10 B should be performed. As will be described in more detail below, the electronic controller  60 B is operable to control the components of the washer  10 B such that the washer  10 B solicits user input regarding washer performance and adjusts operational parameters of the washer  10 B in response thereto. 
     To do so, the electronic controller  60 B includes a number of electronic components commonly associated with electronic units utilized in the control of electromechanical systems. For example, the electronic controller  60 B may include, amongst other components customarily included in such devices, a processor such as a microprocessor  102 B and a memory device  104 B such as a programmable read-only memory device (“PROM”) including erasable PROM&#39;s (EPROM&#39;s or EEPROM&#39;s). The memory device  104 B is provided to store, amongst other things, instructions in the form of, for example, a software routine (or routines) which, when executed by the microprocessor  102 B, allows the electronic controller  60 B to control operation of the washer  10 B. 
     The electronic controller  60 B also includes an analog interface circuit  106 B. The analog interface circuit  106 B converts the output signals from the sensors into signals which are suitable for presentation to an input of the microprocessor  102 B. In particular, the analog interface circuit  106 B, by use of an analog-to-digital (A/D) converter (not shown) or the like, converts the analog signals generated by the sensors into digital signals for use by the microprocessor  102 B. It should be appreciated that the A/D converter may be embodied as a discrete device or number of devices, or may be integrated into the microprocessor  102 B. It should also be appreciated that if any one or more of the sensors associated with the washer  10 B generate a digital output signal, the analog interface circuit  106 B may be bypassed. 
     Similarly, the analog interface circuit  106 B converts signals from the microprocessor  102 B into output signals which are suitable for presentation to the electrically-controlled components associated with the washer  10 B (e.g., the drive mechanism  44 B). In particular, the analog interface circuit  106 B, by use of a digital-to-analog (D/A) converter (not shown) or the like, converts the digital signals generated by the microprocessor  102 B into analog signals for use by the electronically-controlled components associated with the washer  10 B. It should be appreciated that, similar to the A/D converter described above, the D/A converter may be embodied as a discrete device or number of devices, or may be integrated into the microprocessor  102 B. It should also be appreciated that if any one or more of the electronically-controlled components associated with the washer  10 B operate on a digital input signal, the analog interface circuit  106 B may be bypassed. 
     Thus, the electronic controller  60 B may control the operation of the washer  10 B. In particular, the electronic controller  60 B executes a routine including, amongst other things, a control scheme in which the electronic controller  60 B monitors the outputs of the sensors associated with the washer  10 B, including the damper sensor  80 B, the seal sensor  90 B, and the sensors of the active balancing system  100 B, to control the inputs to the electronically-controlled components associated therewith. To do so, the electronic controller  60 B communicates with the sensors directly or indirectly to determine, amongst numerous other things, the state of the drive mechanism  44 B and the heating element  68 B. Armed with this data, the electronic controller  60 B performs numerous calculations, either continuously or intermittently, including looking up values in preprogrammed tables, in order to execute algorithms to perform such functions as energizing the electric motor of the drive mechanism  44 B, energizing the heating element  68 B, activating an indicator on the control panel  46 B, and so on. 
     As described above, the washer  10 B includes an active balancing system  100 B to counteract uneven or unbalanced loads in the drum  20 B. Referring now to  FIG. 21 , the active balancing system  100 B includes a fluid-based balance assembly  110 B that is integrated into the drum  20 B. An exemplary fluid-based balance assembly  110 B is shown and described in U.S. Pat. No. 5,913,951 entitled “RADIALLY ORIENTED MOTOR FOR A FLUID BALANCE RING,” which is expressly incorporated herein by reference. In the illustrative embodiment, the drum  20 B of the washer  10 B includes an outer cylindrical shell  112 B extending from a front end  114 B to a rear end  116 B. The balance assembly  110 B includes a frame  118 B that is positioned in the shell  112 B. In the illustrative embodiment, the frame  118 B and the shell  112 B cooperate to define the chamber  24 B of the drum  20 B. 
     As shown in  FIG. 21 , the frame  118 B of the balance assembly  110 B includes a base plate  120 B and a front ring  122 B that is spaced apart from the base plate  120 B. The plurality of baffles  26 B of the drum  20 B extend between the base plate  120 B and the front ring  122 B. The baffles  26 B, the plate  120 B, and the front ring  122 B are integrally formed as a single monolithic component. It should be appreciated that in other embodiments those structures may be formed separately and later assembled into the frame  118 B. 
     A plurality of compartments  124 B are defined in the front ring  122 B and enclosed by a front cover  136 B. A corresponding plurality of compartments  138 B are defined in the base plate  120 B and enclosed by a rear cover  148 B. In the illustrative embodiment, each pair of compartments  124 B is interconnected by a solenoid valve  126 B, which may be actuated to permit fluid to move between those compartments. Similarly, each pair of compartments  138 B is interconnected by a solenoid valve  126 B, which may be actuated to permit fluid to move between those compartments. In the illustrative embodiment, each pair of compartments  138 B corresponds to a pair of compartments  124 B of the front ring  122 B. Additionally, a single solenoid  126 B may be operated to interconnect two compartments  124 B and separately interconnect two compartments  138 B. In that way, fluid is moved between two compartments  124 B in the front ring  122 B at the same time fluid is moved between the corresponding two compartments  138 B in the base plate  120 B. 
     As shown in  FIG. 21 , an outer chamber  152 B is defined in each baffle  26 B of the frame  118 B. Each outer chamber  152 B houses a solenoid valve  126 B, a pump  154 B, and a motor  156 B that is coupled to the pump  154 B. Additionally, each baffle  26 B includes a cover  158 B to seal the outer chamber  152 B against fluid leakage. In the illustrative embodiment, each motor  156 B is operable to drive the pump  154 B to move fluid between a pair of compartments  124 B and to move fluid between a pair of compartments  138 B when the corresponding solenoid valve  126 B is in the open position. The controller  60 B is operable to control the motors  156 B and the solenoid valves  126 B to move fluid between the compartments  124 B and between the components  138 B to actively balance the weight distribution of the drum  20 B during the operation of the washer  10 B. It should be appreciated that, in some embodiments, actuators other than the solenoid valves  134 B may be used. For example, linear actuators that use small amounts of power (e.g., muscle wire) may be used. 
     In the illustrative embodiment, the front ring  122 B includes a compartment  128 B that is connected to a compartment  130 B via a solenoid valve  134 B. Further, the base plate  120 B includes a compartment  144 B that is connected to a compartment  146 B via the same solenoid valve  134 B that connects the compartments  128 B,  130 B in the front ring  122 B. Each solenoid valve  126 B includes an armature (not shown) configured to move between an open position and a closed position, such that the solenoid valve  126 B permits fluid to pass between, for example, the compartments when in the open position and prevents the passage of fluid when in the closed position. In the illustrative embodiment, when the solenoid valve  134 B is actuated, fluid is permitted to advance from the compartment  128 B to the compartment  130 B and back again. At the same time, fluid is permitted to advance from the compartment  144 B to the compartment  146 B and back again to balance the load. 
     The active balancing system  100 B includes a plurality of piezoelectric power generators  160 B that are secured to the drum  20 B and are configured to provide power on the drum  20 B. In the illustrative embodiment, the generators  160 B are the exclusive power supplies on the drum  20 B and are configured to provide power to the solenoid valves  126 B, the pumps  154 B, the motors  156 B, transmitter circuitry  162 B, and receiver circuitry  164 B positioned on the drum  20 B. In that way, those electrical components do not require power from the power supply circuit  62 B (and hence the AC mains power source  56 B). 
     Each generator  160 B includes an elongated arm  166 B that extends from a baffle  26 B. Each arm  166 B is cantilevered and has a piezoelectric film element  168 B positioned thereon. An exemplary film element  168 B is the LDT1-028K Piezo Sensor, which is commercially available from Seeed Studio of Shenzhen, China. It should be appreciated that the film element may be formed from a piezoelectric ceramic, such as, for example, lead zirconate titanate (PZT). In other embodiments, the piezoelectric element may also be formed from an electroactive polymer (EAP) such as, for example, a stretchable dielectric elastomer. 
     When laundry and fluid are circulated in the drum  20 B, the force of the laundry and fluid causes the cantilevered arm  166 B to deflect. When the cantilevered arm  166 B is deflected, the corresponding film element  168 B is bent, thereby causing the generator  160 B to produce power. The piezoelectric film element  168 B generates electrical power proportional to the degree of bending; as such, the amount of electrical power generated by the film element  168 B is proportional to the amount of deflection of the arm  166 B. In the illustrative embodiment, each film element  168 B may produce power in the range of approximately 500 μW to 1 Watt. It should be appreciated that the generators  160 B may be otherwise shaped and/or coupled to the drum  20 B in other embodiments. 
     The power generated by the elements  168 B is supplied to the transmitter circuitry  162 B and the receiver circuitry  164 B positioned on the drum  20 B. The transmitter circuitry  162 B is configured to transmit a wireless data signal when energized. In the illustrative embodiment, the transmitter circuitry  162 B uses a Bluetooth transmission protocol. The electrical power generated by the generators  160 B energizes the transmitter circuitry  162 B such that the wireless data signal is transmitted. Similarly, the receiver circuitry  164 B of the system  100 B is configured to receive wireless data signals when energized. In the illustrative embodiment, the receiver circuitry  164 B also uses a Bluetooth transmission protocol. 
     As shown in  FIG. 20 , the washer  10 B includes receiver circuitry  170 B that is not positioned on the drum  20 B and configured to receive the data signals generated by the transmitter circuitry  162 B. For example, the receiver circuitry  170 B may be positioned in the cabinet  12 B outside of the drum  20 B. In the illustrative embodiment, the receiver circuitry  170 B is configured to use the Bluetooth transmission protocol. It should be appreciated that the receiver circuitry  170 B may be embodied as any type of wireless receiver capable of receiving the data signals from the transmitter circuitry  162 B. For example, the wireless receiver may be embodied as a wireless router. The receiver circuitry  170 B is communicatively coupled to the electronic controller  60 B via a number of communication links such as wires, cables, or the like. 
     The washer  10 B also includes transmitter circuitry  172 B that is not positioned on the drum  20 B and communicatively coupled to the electronic controller  60 B via a number of communication links. Like the receiver circuitry  170 B, the transmitter circuitry  172 B may be positioned in the cabinet  12 B outside of the drum  20 B. In the illustrative embodiment, the transmitter circuitry  172 B is configured to use the Bluetooth transmission protocol and is configured to transmit signals to the receiver circuitry  164 B of the system  100 B. It should be appreciated that the transmitter circuitry  172 B may be embodied as any type of wireless transmitter capable of sending data signals to the receiver circuitry  164 B of the balancing system  100 B. 
     In use, a user may open the door  38 B to place laundry in the chamber  24 B of the drum  20 B and utilize the control panel  46 B to select a laundry cycle and activate the washer  10 B. In response to a user input from the control panel  46 B, the controller  60 B may operate various electrical components of the washer  10 B to execute the cycle. The controller  60 B may operate the power supply circuit  62 B to energize the drive mechanism  44 B. As described above, when the drive mechanism  44 B is energized, the drum  20 B is rotated relative to the tub  14 B about the axis  22 B. 
     The rotation of the drum  20 B causes the tub  14 B to vibrate. As described above, the tub  14 B is supported by a number of dampers  16 B to damp vibration of the tub  14 B. The damper rod  52 B moves into and out of the damper cylinder  50 B based on the vibration of the tub  14 B. Further, as described above, a piezoelectric power generator  82 B is coupled to the damper  16 B. As the generator  82 B is moved back and forth between its initial length and its stretched length, the generator  82 B generates electrical power, which is supplied to the controller  60 B in the form of an electrical signal. The controller  60 B may use the signal to determine, for example, the operating frequency of the damper  16 B and hence the tub  14 B. 
     The rotation of the drum  20 B also causes the seal  40 B to stretch or flex due to the movement of the tub  14 B. The piezoelectric power generator  94 B secured to the seal  40 B generates power when the seal  40 B is stretched or flexed. As described above, the generator  94 B may be electrically coupled to a mold detector  92 B, which detects the odor or chemical composition of mold or other biological films on the seal  40 B. The generator  94 B provides the electrical power necessary for the detector  92 B to operate. The detector  92 B transmits an electrical output signal indicative of the presence of mold to the controller  60 B when mold is detected. In response to the detection of mold, the controller  60 B may, for example, activate an alarm on the control panel  46 B to notify the user of the mold. 
     The rotation of the drum  20 B may also be used to generate power for the active balancing system  100 B. As described above, a plurality of baffles  26 B extend between the base plate  120 B and the front ring  122 B of the drum  20 B. A number of piezoelectric power generators  160 B are secured to the drum  20 B (e.g., to the baffles  26 B). When laundry and fluid are circulated in the drum  20 B, the force of the laundry and fluid applied to the generators  160 B causes the generators  160 B to deflect and, therefore, to produce power. The power generated by the generators  160 B may be used to provide power to electrical components positioned on the drum  20 B such as the solenoid valves  126 B, the pumps  154 B, the motors  156 B, transmitter circuitry  162 B, and receiver circuitry  164 B. 
     The transmitter circuitry  162 B and the receiver circuitry  164 B operate in tandem to communicate with electrical components not positioned on the drum  20 B such as the controller  60 B. For example, the transmitter circuitry  162 B may provide sensor data to the controller  60 B for analysis. The controller  60 B may determine that the drum  20 B is unbalanced based on the analysis. For example, a greater displacement of one or more of the dampers  16 B may indicate a greater amount of unbalance. In another embodiment, the damper sensor  80 B may include a strain gauge or other force gauge to measure the force exerted on the damper  16 B by the tub  14 B, which may be used to measure the amount of unbalance of the washer  10 B. In response to determining the drum  20 B is unbalanced, the controller  60 B transmits instructions to the receiver circuitry  164 B regarding an action to be performed to achieve balance. For example, the controller  60 B may operate a number of solenoid valves  126 B to open the valves  126 B and allow fluid to flow between the corresponding pairs of compartments  124 B,  138 B. The controller  60 B may then energize the corresponding motors  156 B to operate the pumps  154 B to pump the fluid between the pairs of compartments  124 B. Meanwhile, the transmitter circuitry  162 B continues to provide sensor data to the controller  60 B. When the controller  60 B determines that balance has been achieved, the controller  60 B stops operation of the solenoid valves  126 B and the motors  156 B. It should be appreciated that a battery may be positioned on the drum  20 B and configured to store power generated by the generators  160 B but not used by the electrical components positioned on the drum  20 B. Further, the battery may supply power to the electrical components when the amount of power supplied by the generators  160 B is insufficient to operate the electrical components. 
     Referring now to  FIG. 22 , the washer  10 B may include another embodiment of an active balancing system (hereinafter system  200 B) similar to that discussed above with regard to  FIG. 21 . For ease of description, those structures in  FIG. 22  that are substantially identical to the structures shown and described above in regard to  FIG. 21  are identified with the same reference numbers. As shown in  FIG. 22 , the active balancing system  200 B includes a mass-based balance assembly  210 B that is integrated into the drum  20 B. The drum  20 B of the washer  10 B includes an outer cylindrical shell  112 B extending from a front end  114 B to a rear end  116 B. The balance assembly  210 B includes a frame  218 B that is positioned in the shell  112 B. In the illustrative embodiment, the frame  218 B and the shell  112 B cooperate to define the chamber  24 B of the drum  20 B. 
     As shown in  FIG. 22 , the frame  218 B of the balance assembly  210 B includes a base plate  220 B and a front ring  222 B that is spaced apart from the base plate  220 B. The plurality of baffles  26 B of the drum  20 B extend between the base plate  220 B and the front ring  222 B. The baffles  26 B, the plate  220 B, and the front ring  222 B are integrally formed as a single monolithic component. It should be appreciated that in other embodiments those structures may be formed separately and later assembled into the frame  218 B. 
     A plurality of compartments  224 B are defined in the front ring  222 B. In the illustrative embodiment, each pair of compartments  224 B is interconnected by a solenoid-operated gate  226 B. Each compartment  224 B is sized to receive a number of rolling mass elements  228 B, which are illustratively embodied as spheres. It should be appreciated that in other embodiments the mass elements  228 B may be embodied as cylindrical pins or other shapes that permit mass elements  228 B to roll within and between the compartments  224 B. The solenoid-operated gate  226 B may be actuated to permit the mass elements  228 B to move between each pair of compartments  224 B. 
     For example, the compartments  224 B include a compartment  230 B that is connected to a compartment  232 B via a solenoid-operated gate  234 B. The gate  234 B may be actuated to permit mass elements  236 B to advance from the compartment  230 B to the compartment  232 B and back again. In the illustrative embodiment, each gate  234 B is configured to move between an open position and a closed position, such that the gate  234 B permits mass elements  236 B to pass between, for example, the compartments  230 B,  232 B, when in the open position and prevents the mass elements  236 B from passing when in the closed position. As shown in  FIG. 22 , the compartments  224 B are enclosed by a front cover  238 B. 
     A plurality of compartments  244 B are defined in the base plate  220 B. In the illustrative embodiment, each pair of compartments  244 B is interconnected by a solenoid-operated gate  246 B. Additionally, each pair of compartments  244 B corresponds to a pair of compartments  224 B of the front ring  122 B. Each compartment  244 B is sized to receive a number of rolling mass elements  228 B. The solenoid-operated gate  246 B may be actuated to permit the mass elements  228 B to move between each pair of compartments  244 B. 
     For example, the compartments  244 B include a compartment  250 B that is connected to a compartment  252 B via a solenoid-operated gate  254 B. The gate  254 B may be actuated to permit mass elements  256 B to advance from the compartment  250 B to the compartment  252 B and back again. In the illustrative embodiment, each gate  254 B is configured to move between an open position and a closed position, such that the gate  254 B permits the mass elements  256 B to pass between, for example, the compartments  250 B,  252 B, when in the open position and prevents the passage of the mass elements  256 B when in the closed position. As shown in  FIG. 22 , the compartments  224 B are enclosed by a rear cover  258 B. 
     As shown in  FIG. 22 , an outer chamber  262 B is defined in each baffle  26 B of the frame  218 B. Each outer chamber  262 B houses a solenoid valve  264 B configured to operate one of the gates  226 B of the front ring  222 B and the corresponding gate  234 B of the base plate  220 B. Each baffle  26 B includes a cover  268 B to seal the outer chamber  262 B against fluid leakage. 
     The active balancing system  200 B includes a plurality of piezoelectric power generators  160 B that are secured to the drum  20 B and are configured to provide power on the drum  20 B. In the illustrative embodiment, the generators  160 B are the exclusive power supplies on the drum  20 B and are configured to provide power to the solenoid valves  264 B, transmitter circuitry  162 B, and receiver circuitry  164 B positioned on the drum  20 B. In that way, those electrical components do not require power from the power supply circuit  62 B (and hence the AC mains power source  56 B). In some embodiments, the generators  160 B are additionally configured to provide power to motors that move the mass elements  228 B to accomplish active balancing. 
     In the illustrative embodiment, piezoelectric power generators  160 B generate electrical power to operate the valves  264 B. As described above, the generators  160 B may be mounted on the baffles  26 B. However, in another embodiment, the generators  160 B may be mounted inside the compartments  224 B,  244 B and may generate electrical power as the mass elements  228 B roll therethrough. For example, the generators  160 B may be embodied as cantilever beams positioned at the gates  226 B and configured to deflect as the mass elements  228 B roll through the compartments  224 B,  244 B and apply a force to the generators  160 B. 
     In response to determining the drum  20 B is unbalanced, the controller  60 B transmits instructions to the receiver circuitry  164 B regarding an action to be performed to achieve balance. For example, the controller  60 B may operate a number of solenoid valves  264 B to open a number of the gates  234 B,  246 B and permit the mass elements  236 B,  256 B between the corresponding pairs of compartments  224 B,  244 B, respectively. Meanwhile, the transmitter circuitry  162 B continues to provide sensor data to the controller  60 B. When the controller  60 B determines that balance has been achieved, the controller  60 B stops operation of the solenoid valves  264 B, thereby closing the gates  234 B,  246 B and trapping the mass elements  236 B,  256 B within the compartments. In some embodiments, the controller  60 B may instruct the valves  264 B to stay closed until a certain threshold frequency is reached (e.g., 300 rotations per minute) to improve functionality of the system. 
     It should be appreciated that the concepts illustrated above may be applied to other aspects of the operation of an appliance. For example, a piezoelectric power generator may be secured to a fluid inlet of the washer  10 B to generate electrical power as the water flows into the tub  14 B under pressure during a wash cycle. The power generated by such a generator may be used in conjunction with one or more electrical components  64  (e.g., sensors) for a variety of functions. For example, a sensor may be placed in the fluid inlet and act as a flow totaler and/or used as a safety device to cut-off filling the tub  14 B in the event of a leak. 
     Alternatively or additionally, the piezoelectric generator may be mounted to the drum  20 B and/or the baffles  26 B and may power a sensor used to sense the existence of a water ring or suds condition during a wash cycle. In some embodiments, the generator itself may be used to sense the amount of water and suds. It should be appreciated that the generator would have a different amount of flex as it rotates through water than through suds due to the different forces applied by those substances. As such, the generator would generate a different amount of power based on the substance through which it is passed. In another embodiment, the generator may (e.g., in conjunction with a sensor) sense suds on the door  38 B of the washer  10 B. In such an embodiment, the generator may be mounted on a hinge of the door  38 B and generate electrical power as the door  38 B is opened and closed. The generator may power a sensor used to measure, for example, the pressure, the reflectance, and/or capacitance of suds on the door  38 B. 
     As described above, the washer  10 B includes a number of piezoelectric generators  160 B that flex as they engage the contents of the washer  10 B such as laundry and washing fluid. In some embodiments, the generator  160 B may be electrically coupled to a sensor that detects the amount of flex. This data may be transmitted (e.g., via a transmitter  162 B) to the controller  60 B, and the controller  60 B may determine the load size, load type, speed of the drum  20 B, fluid level, and/or efficiency of energy transfer. 
     In another embodiment, piezoelectric power generators may power sensors used to determine the bending moment on the drive shaft of the washer  10 B, which is an indication of the forces in the bearings and a rear portion of the tub  14 B. To do so, the sensors may monitor the displacement of the dampers  16 B and the relationship between the front dampers  16 B and the rear dampers  16 B of the washer  10 B. If the load size is known, it may be used by the controller  60 B to determine if the bending moment has been exceeded. 
     It should be appreciated that at high speeds, the side walls of the tub  14 B deflect, thereby causing the tub to become elliptical due to the flexing. As such, a piezoelectric generator may be mounted on the tub  14 B and used to generate electrical power during high spin speeds of the drum  20 B and to sense the amount of laundry not in balance at those speeds (e.g., using a sensor). Although the concepts are described herein with regard to horizontal axis washers, the concepts described herein may be applied to vertical axis washers in other embodiments. Additionally, the concepts described herein may be applied to other domestic appliances, such as, for example, a dryer for laundry. 
     There are a plurality of advantages of the present disclosure arising from the various features of the method, apparatus, and system described herein. It will be noted that alternative embodiments of the method, apparatus, and system of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of the method, apparatus, and system that incorporate one or more of the features of the present invention and fall within the spirit and scope of the present disclosure.