Patent Publication Number: US-8973612-B2

Title: Capacitive sensing electronic faucet including differential measurements

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Provisional Application Ser. No. 61,497,793, filed Jun. 16, 2011. 
    
    
     BACKGROUND AND SUMMARY 
     The present disclosure relates generally to electronic faucets. Electronic faucets are often used to control fluid flow. Electronic faucets may include proximity sensors such as active infrared (“IR”) proximity detectors or capacitive proximity sensors. Such proximity sensors are used to detect a user&#39;s hands positioned near the faucet, and turn the water on and off in response to detection of the user&#39;s hands. Other electronic faucets may use touch sensors to control the faucet. Such touch sensors include capacitive touch sensors or other types of touch sensors located on a spout of the faucet or on a handle for controlling the faucet. Capacitive sensors on the faucet may also be used to detect both touching of faucet components and proximity of the user&#39;s hands adjacent the faucet 
     In capacitive sensing faucet applications, other components located near the electronic faucet may have unintended effects on the output signal from the capacitive sensors. For instance, a user touching a metal sink basin may induce a false capacitive signal at the capacitive sensors. Changes that occur below a sink deck may also cause false readings at the capacitive sensors. 
     In an illustrated embodiment of the present disclosure, a fluid delivery device includes an electronic faucet having a plurality of faucet components, and a primary capacitive sensor coupled to a component of the electronic faucet to sense a user touching or in proximity to the faucet component. The primary capacitive sensor provides an output signal. The fluid delivery device also includes at least one secondary capacitive sensor located on or near an item which causes unintended effects on the output signal from the primary capacitive sensor. Each secondary capacitive sensor also provides an output signal. The fluid delivery device further includes a controller coupled to the primary and secondary capacitive sensors. The controller determines a difference signal between the output signals of the primary and secondary capacitive sensors. The difference signal is used by the controller to detect when a user touches or is in proximity to the faucet component. 
     In illustrated embodiments, the at least one secondary sensor is at least one of a metal plate or electrode located near or coupled to the metal sink basin, a sensor coupled to a sense wire from the primary capacitive sensor, a sensor coupled to a drain to sense fluid going down the drain, a sensor coupled to a garbage disposal, and a sensor coupled to a fluid supply line. In other illustrated embodiments, the at least one secondary sensor is coupled to water-carrying equipment located below a sink deck, or to metal equipment or other equipment connected to water or located below the sink deck. In another illustrated embodiment, the at least one secondary sensor is used as an antenna to reduce electromagnetic interference (EMI) or electrostatic discharge (ESD) false activations. 
     In a further illustrative embodiment of the present disclosure, a fluid delivery device includes an electronic faucet having a spout, and an electrically operable valve to control water flow through the spout. A primary capacitive sensor is coupled to the spout, the primary capacitive sensor providing a primary output signal in response to a user input to the spout. A secondary capacitive sensor is coupled to a secondary component which causes unintended effects on the primary output signal from the primary capacitive sensor, the secondary capacitive sensor providing a secondary output signal in response to user input to the secondary component. A controller is coupled to the primary and secondary capacitive sensors, the controller determining a difference signal between the primary and secondary output signals of the primary and secondary capacitive sensors, the difference signal being used by the controller to control operation of the electrically operable valve. 
     A method of controlling an electronic faucet includes the steps of capacitively sensing a user touching or in proximity to a faucet component and providing a primary output signal in response thereto, and capacitively sensing input from an item which causes unintended effects on the primary output signal and providing a secondary output signal in response thereto. The method further includes determining a signal difference between the primary and secondary output signals to detect when a user touches or is proximity to the faucet component. 
     Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiment exemplifying the best mode of carrying out the invention as presently perceived. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description of the drawings particularly refers to the accompanying figures in which: 
         FIG. 1  is a block diagram of an illustrated embodiment electronic faucet; 
         FIG. 2  is a block diagram illustrating further details of the electronic faucet of an illustrated embodiment of the present disclosure including at least one primary capacitive sensor coupled to a component of the faucet, such as a spout or a handle, and a plurality of secondary capacitive sensors to measure unintended capacitive signals near the faucet; and 
         FIG. 3  illustrates exemplary output signals from a primary capacitive sensor and a secondary capacitive sensor, and a difference signal between the primary and secondary capacitive sensor output signals. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     For the purposes of promoting an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings, which are described below. The embodiments disclosed below are not intended to be exhaustive or limit the invention to the precise form disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings. Therefore, no limitation of the scope of the claimed invention is thereby intended. The present invention includes any alterations and further modifications of the illustrated devices and described methods and further applications of the principles of the invention which would normally occur to one skilled in the art to which the invention relates. 
       FIG. 1  is a block diagram showing one illustrative embodiment of an electronic faucet  10  of the present disclosure. The faucet  10  illustratively includes a spout  12  for delivering fluids such as water and at least one manual valve handle  14  for controlling the flow of fluid through the spout  12  in a manual mode. A hot water source  16  and cold water source  18  are coupled to a manual valve body assembly  20  by fluid supply lines  17  and  19 , respectively. The valve handle  14  is operably coupled to the manual valve body assembly  20  to control water flow therethrough. 
     In one illustrated embodiment, separate manual valve handles  14  are provided for the hot and cold water sources  16 ,  18 . In other embodiments, such as a kitchen faucet embodiment, a single manual valve handle  14  is used for both hot and cold water delivery. In such kitchen faucet embodiment, the manual valve handle  14  and spout  12  are typically coupled to a basin through a single hole mount. An output of valve body assembly  20  is coupled to an actuator driven valve  22  which is controlled electronically by input signals received from a controller  24 . In an illustrative embodiment, actuator driven valve  22  is an electrically operable valve, such as a solenoid valve. An output of actuator driven valve  22  supplies fluid to the spout  12  through supply line  23 . 
     In an alternative embodiment, the hot water source  16  and cold water source  18  are connected directly to actuator driven valve  22  to provide a fully automatic faucet without any manual controls. In yet another embodiment, the controller  24  controls an electronic proportioning valve (not shown) to supply fluid to the spout  12  from hot and cold water sources  16 ,  18 . 
     Because the actuator driven valve  22  is controlled electronically by controller  24 , flow of water can be controlled using outputs from sensors such as capacitive sensors  26 ,  28 . As shown in  FIG. 1 , when the actuator driven valve  22  is open, the faucet  10  may be operated in a conventional manner, i.e., in a manual control mode through operation of the handle(s)  14  and the manual valve member of valve body assembly  20 . Conversely, when the manually controlled valve body assembly  20  is set to select a water temperature and flow rate, the actuator driven valve  22  can be touch controlled, or activated by proximity sensors when an object (such as a user&#39;s hands) are within a detection zone to toggle water flow on and off. 
     In one illustrated embodiment, spout  12  has a capacitive sensor  26  connected to controller  24 . In addition, the manual valve handle(s)  14  also have capacitive sensor(s)  28  mounted thereon which are electrically coupled to controller  24 . The output signals from capacitive sensors  26 ,  28  are used to control actuator driven valve  22  which thereby controls flow of water to the spout  12  from the hot and cold water sources  16  and  18 . By sensing capacitance changes with capacitive sensors  26 ,  28 , the controller  24  can make logical decisions to control different modes of operation of faucet  10  such as changing between a manual mode of operation and a hands free mode of operation as further described in U.S. Application Publication No. 2010/0170570; and U.S. Pat. Nos. 7,690,395 and 7,150,293; and 7,997,301, the disclosures of which are all expressly incorporated herein by reference. Another illustrated configuration for a proximity detector and logical control for the faucet in response to the proximity detector is described in greater detail in U.S. Pat. No. 7,232,111, which is hereby incorporated by reference in its entirety. 
     The amount of fluid from hot water source  16  and cold water source  18  is determined based on one or more user inputs, such as desired fluid temperature, desired fluid flow rate, desired fluid volume, various task based inputs, various recognized presentments, and/or combinations thereof. As discussed above, the faucet  10  may also include an electronically controlled proportioning or mixing valve which is in fluid communication with both hot water source  16  and cold water source  18 . Exemplary electronically controlled mixing valves are described in U.S. patent application Ser. No. 11/109,281 and PCT International Application Serial No. PCT/US2007/060512, the disclosures of which are expressly incorporated by reference herein. 
     Additional details of an exemplary embodiment of the electronic faucet are illustrated in  FIG. 2 .  FIG. 2  illustrates a faucet  10  including at least one primary capacitive sensor  26 ,  28  located on a component of the faucet such as a spout  12  or a handle  14  as discussed above. The primary capacitive sensor  26 ,  28  detects touching of a faucet component or proximity of a user in a detection region located near the faucet component. The primary capacitive sensor(s)  26 ,  28  is (are) illustratively coupled to a processor or controller  24  used to actuate valve  22  in response to detecting the touching of the faucet  10  or detecting the user (e.g. hands, arms, etc.) in close proximity to the faucet  10  for hands-free activation of the faucet  10  as discussed above. 
     In capacitive sensing in faucet applications, other components located near the faucet  10  may have unintended effects on the output signal from the primary capacitive sensor(s)  26 ,  28 . For instance, a user touching a metal sink basin  30  may induce a false capacitive signal at the primary capacitive sensor(s)  26 ,  28 . Changes that occur below a sink deck  32  may also cause false readings at the primary capacitive sensor(s)  26 ,  28 . These below deck changes may include, for example, water going down a drain  34  or someone moving an object below the deck  32 . A garbage disposal  36  or other static electricity source may also have an effect on readings of the primary capacitive sensor(s)  26 ,  28 . In addition, a 60 Hz hum of AC power systems located below the deck  32  may also affect the primary capacitive sensor(s)  26 ,  28  output signals. 
     In order to counter the unintended effects discussed above, the present system uses at least one secondary capacitive sensor  40  to detect the unintended capacitive signals. Multiple secondary capacitive sensors  40 A- 40 G are illustrated in  FIG. 2 . Sensors  40 A- 40 G are used to reduce different capacitive effects in a faucet  10 . For instance, secondary capacitive sensor  40 A is illustratively a metal plate or electrode located near or coupled to the metal sink basin  30  to reduce the effect of touching the metal sink basin  30 . Such touching of the basin  30  may be confused by the controller  24  as a hands-free or proximity activation of the primary sensor(s)  26 ,  28 . 
     Secondary capacitive sensor  40 B is wrapped around or otherwise coupled to a sense wire  42  from primary capacitive sensor(s)  26 ,  28  to reduce the likelihood of activating the faucet  10  when the below deck sense wire  42  is moved or touched. A secondary capacitive sensor  40  may also be used as an antenna to reduce electromagnetic interference (EMI) or electrostatic discharge (ESD) false activations. 
     In an illustrated embodiment, a secondary sensor  40 C is used to sense water going down the drain  34 . Sensor  40 C is useful to detect capacitive changes when water flows from sink basin  30  through drain  34 . A secondary capacitive  40  may also be used on other drains under the sink, such as dishwasher drains or the like. Secondary capacitive sensors  40  are useful on any water-carrying equipment located below the deck  32  or under the sink basin  30 , and any metal equipment or other equipment connected to water or located under the sink deck  32 . 
       FIG. 2  also illustrates a secondary capacitive sensor  40 D coupled to the garbage disposal  36 . In addition, sensors  40 E,  40 F and  40 G are shown coupled to fluid supply lines  23 ,  17  and  19 , respectively, to sense capacitive changes when water flows therethrough. 
     As shown in  FIG. 3 , an output signal from the at least one secondary capacitive sensor  40  is subtracted from the primary capacitive sensor(s)  26 ,  28  output signal so that the controller  24  more accurately measures the touch or proximity readings from the primary capacitive sensor(s)  26 ,  28 . As shown in  FIG. 3 , signal A is the output signal from a primary capacitive sensor  26 ,  28  and signal B is the output signal from a secondary capacitive sensor  40 . When B is subtracted from A, the touch or proximity event from the primary sensor(s)  26 ,  28  is easier to detect in the difference signal (A-B). The controller  24  processes the difference signal to more accurately measure the touch or proximity events detected by the primary capacitive sensor(s)  26 ,  28 . In other words, the controller  24  accounts for input from the secondary capacitive sensor  40  when deciding whether to take action (e.g., control actuator driven valve  22 ). 
     While this disclosure has been described as having exemplary designs and embodiments, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains. Therefore, although the invention has been described in detail with reference to certain illustrated embodiments, variations and modifications exist within the spirit and scope of the invention as described and defined in the following claims.