Abstract:
A refrigerator includes a dispenser, a dispenser well, a control for regulating a dispensing operation, and a sensor system for automatically initiating and terminating the dispensing operation. The sensor system includes at least one capacitive-type sensor mounted in the dispenser well. The sensor is configured to detect the presence of a container in the dispenser well, an upper edge portion of the container and a level of liquid filling the container during the dispensing operation. The sensor signals the control to automatically cease the dispensing operation before the level of liquid reaches the upper edge portion of the container. The control is configured to differentiate between animate and inanimate objects, while preventing any release of water or ice when an animate object is detected.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/877,668 filed Dec. 29, 2006 entitled “Sensor System for a Refrigerator Dispenser.” 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention pertains to the art of refrigerators and, more particularly, to a sensor system employed in a dispenser mounted in a refrigerator door. 
     2. Description of the Related Art 
     Refrigerators having built-in ice/water dispensers are well known in the art. In general, the dispensers are mounted to a door of the refrigerator for the purpose of dispensing ice and/or water without requiring a user to access a refrigerator compartment. A typical dispenser includes a dispenser well into which a container is placed. Once the container is in position, an actuator is operated to release the ice and/or water into the container. 
     In many cases, the actuator is a pressure sensitive mechanical switch. Typically, the switch is operated by pushing the container against, for example, a lever. The lever, in turn, operates the switch that causes the ice and/or water to be dispensed. A number of dispensers employ multiple actuators, one for ice and another for water, while other dispensers employ a single actuator. Dispensers which employ a single actuator typically require additional control elements that enable a user to select between ice and water dispensing operations. Several manufacturers have converted from mechanical switches to electrical or membrane switches. Functioning in a similar manner, a container is pushed against the membrane switch to initiate the dispensing operation. Still other arrangements employ actuator buttons provided on a control panel of the dispenser. With this arrangement, the user continuously depresses a button to release ice and/or water into the container. In yet another arrangement, ultrasonic sensors are mounted in the dispenser well and function to sense a presence and size of the container. The dispenser automatically begins dispensing ice or water based on the presence of the container and stops dispensing before the container overfills. 
     Over time, mechanical and membrane switches wear out. Physical interaction with the switches results in wear and tear on contact points, springs, levers and the like which eventually require replacement. In addition, buttons, switches and sensors not only add to the overall cost and complexity of the system, but often poses an attraction to young children. Ever curious, young children will often play with the dispenser controls and release water and/or ice onto kitchen floors. In order to address this problem, several manufactures provide their dispensers with a “Lock-Out” feature which, when active, disables operation of the dispenser. While effective, consumers often don&#39;t want to turn the system on and off as needed. As such, users do not routinely avail themselves of this option. 
     Another drawback with existing systems is the lack of an automatic cut-off feature. More specifically, once activated, the dispenser will discharge water or ice until the pressure is removed from the actuator. If the user is momentarily distracted or if the dispenser is operated by an inexperienced individual such as a child, the level of ice or water can overflow the container. There also exist drawbacks with the systems that employ automatic actuators. Most active sensors cannot differentiate between a container and a child&#39;s hand. Thus, in such systems, the mere act of a child inserting a hand or other object into the dispenser well will initiate a dispensing operation. In addition, active sensors require both the sending and receiving of signals. Sensors of this type may require periodic alignment and necessitate the use of multiple components which further adds to the overall cost and complexity of the appliance. 
     Therefore, despite the existence of refrigerator dispensers in the prior art, there still exists a need for an enhanced refrigerator dispensing system. More specifically, there exists a need for a refrigerator dispensing system that employs passive-type sensors, such as capacitive sensors, which do not require contact by a container or other device to initiate a dispensing operation, yet automatically terminate a dispensing operation when a level of ice or water reaches an upper rim of the container. In addition, there exists a need for a refrigerator dispensing system which automatically differentiates between animate and inanimate objects to prevent inadvertent dispensing operations. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a refrigerator including a cabinet within which is defined at least one refrigerated compartment. A door is pivotally mounted to the cabinet to provide access to the refrigerated compartment. A dispenser assembly is provided in the door to enable users to obtain ice and/or water without requiring access to the refrigerated compartment. The dispenser includes a main body portion, a control portion including a plurality of control elements for selecting a desired dispensing operation, a dispenser well provided in the main body portion, and a sensor system. 
     In accordance with the invention, the sensor system includes at least one passive sensor that is mounted in the dispenser well. The sensor is configured to detect an upper edge portion of a container placed in the dispenser well and a level of liquid filling the container during a dispensing operation. The sensor signals the control to automatically terminate the dispensing operation before the level of liquid in the container reaches the upper edge portion. 
     In accordance with another aspect of the invention, the sensor system is also configured to detect when a container is introduced into the dispenser well and automatically trigger a dispensing operation. More specifically, upon sensing that a container is positioned in the dispenser well, the control automatically begins releasing water or ice into the container based upon user preferences. In addition to sensing the presence of a container, the control is also configured to differentiate between animate and inanimate objects. More specifically, the control automatically initiates a dispensing operation only upon sensing an inanimate object, e.g. a container, in the dispenser well. In the event that an animate object, such as a child&#39;s hand or the like, is introduced into the dispenser well, the control does not release the water or ice. 
     Additional objects, features and advantages of the present invention will become more readily apparent from the following detailed description of a preferred embodiment when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front elevational view of a refrigerator incorporating a dispenser having a sensor system constructed in accordance with the present invention; 
         FIG. 2  is an elevational view of the sensor system of the present invention; and 
         FIG. 3  is an enlarged view of the dispenser of  FIG. 1  illustrating a dispensing operation in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     With initial reference to  FIG. 1 , a refrigerator constructed in accordance with the present invention is generally indicated at  2 . Refrigerator  2  includes a cabinet  4  having a top wall  6 , a bottom  7  and opposing side walls  8  and  9 . In a manner known in the art, refrigerator  2  includes a freezer compartment  11  arranged along side a fresh food compartment  12 . Freezer compartment  11  includes a corresponding freezer compartment door  14  and fresh food compartment  12  includes a corresponding fresh food compartment door  15 . In a manner also known in the art, each door  14 ,  15  includes an associated handle  17 ,  18 . Refrigerator  2  is also shown to include a kick plate  20  arranged at a bottom portion thereof having a vent  21  that permits air to flow into refrigeration components (not shown) that establish and maintain desired temperatures in freezer compartment  11  and fresh food compartment  12 . In the embodiment shown, refrigerator  2  constitutes a side-by-side model. However, it should be understood that the present invention could also be employed in connection with a wide variety of refrigerators, including top mount, bottom mount, and French-style refrigerator models. 
     In accordance with the invention, refrigerator  2  includes a dispenser assembly  40  having a main housing  44  and a control panel  49 . Control panel  49  includes first and second rows of control buttons  53  and  54  which enable a user to select a preferred dispensing operation. Control panel  49  further includes a display  57  which, in addition to functioning in cooperation with dispenser assembly  40 , enables the user to select particular operational parameters for refrigerator  2 , such as desired temperatures for freezer compartment  11  and fresh food compartment  12 . In any case, dispenser assembly  40  includes a dispenser well  63  having a base or container support portion  65  and a recessed, upstanding wall section  68 . A pair of passive sensors  77  and  78  that are concealed by the upstanding wall section  68 , as will be discussed more fully below, control dispensing operations as selected by a user. More specifically, sensors  77  and  78  operate, upon sensing a container  79  ( FIG. 3 ), to automatically activate a valve (not shown) to release water through a spout  80  or an auger mechanism (not shown) to release ice cubes. 
     As stated above, sensors  77  and  78  are passive in nature. That is, in contrast to active sensors, such as ultrasonic, infrared, optical sensors or the like which require both the transmission and receipt of signals, sensors  77  and  78  passively sense the presence of, for example, a container in dispenser well  63 . Most preferably, sensors  77  and  78  are capacitive-type sensors which sense changes in a dielectric constant of materials brought into proximity of back wall section  68  (sensing zones)  114  and  115 . As higher dielectric constants register larger changes in capacitance, the present invention maximizes the detected change in capacitance when a container is brought into proximity of back wall section  68  (sensing zones)  114  and  115  by providing sensors  77  and  78  with corresponding common metal strips  90  and  91 , as well as a series of sensor strips  93 - 100  and  104 - 111  as best shown in  FIG. 2 . Sensor strips  93 - 100  and  104 - 111 , in combination with corresponding ones of common metal strips  90  and  91 , establish a plurality of discrete sensing zones (not separately labeled) which collectively establish respective sensing zones  114  and  115  as indicated by dotted lines in  FIG. 2  for sensors  77  and  78  respectively. By employing multiple sensor strips, the size of each sensor  77 ,  78  is minimized. This is particularly advantageous given that the smaller the sensor, the higher the relative change when a container or other similar inanimate object is brought into proximity. As shown in  FIG. 3 , as container  79  is placed in dispenser well  63 , a control  142  monitors the capacitance of each sensor strip  93 - 100  and  104 - 111  for changes which signal the presence and/or removal of container  79  anywhere proximate to sensing zones  114  and  115 . It should be noted that the shape, size and configuration or layout of the sensor strip should not be limited to that illustrated in  FIG. 2 , as this is merley a potential embodiment. 
     In addition to sensing the presence of container  79 , sensors  77  and  78  determine a position of container  79  in dispenser well  63  by detecting an upper rim portion  144  thereof. In contrast to the prior art which would be capable of detecting a height of a container relative to a bottom wall of the dispenser, the present invention detects the actual location of upper rim portion  144  of container  79 . Thus, in the prior art, if a container where held above the bottom wall, overfilling could still occur as the control would register that a taller container was being used. This is not the case with the present invention given that dispensing terminates before the liquid reaches the upper rim as will be detailed more fully below. In any event, when container  79  is placed within dispenser well  63 , a change in capacitance is detected. The change in capacitance is greatest in those sensing strips  93 - 100  and  104 - 111  directly adjacent container  79 . Any one of sensing strips  93 - 100  and  104 - 111  located above container  79  will exhibit little or no change. In this manner, control  142  monitors the capacitance in each sensor strip  93 - 100  and  104 - 111  and determines not only the presence of container  79  but also the position of upper rim portion  144 . 
     After detecting the presence of container  79  and the location of upper rim portion  144 , water is automatically dispensed into container  79 . As the dielectric constant of water is much greater than most empty containers, including glass and plastic drinking containers, the dielectric constant of the liquid will have an additive effect on the capacitance of each sensor strip  93 - 100  and  104 - 111 . Thus, as the level of water continues to rise in container  79 , the capacitance of, for example, sensor strip  106  changes proportionally with the water height. Once the water is above the top of sensor strip  106 , the capacitance associated therewith ceases to change or, at best, will change very little. In this manner, control  142  can readily determine the location of the water relative to upper rim portion  144  by monitoring the change of capacitance of each sensing strip  93 - 100  and  104 - 111 . This arrangement provides a high degree of accuracy, while still permitting the use of a relatively minimum number of sensor strips. Thus, in accordance with the most preferred form of the invention, control  142  initiates a dispensing operation upon receipt of a signal indicating the presence of container  79 , and control  142  will continue the dispensing of either water from spout  80  and/or ice through a chute (not shown) until the fill level is a predetermined spacing, such as one inch (approximately 2.5 cm), from upper rim  144  of container  79 , at which point the dispensing operation is automatically terminated. 
     In addition to the above, sensors  77  and  78  also act as a safety feature for dispenser assembly  40 . More specifically, sensors  77  and  78  can differentiate between animate and inanimate objects. That is, using the theory that animate objects tend to reduce an amount of charge stored on a capacitor rather than increase the charge, sensors  77  and  78  are able to differentiate between a container and, for example, a hand. In the event that a hand or other animate object is inserted into dispenser well  63 , control  142  will not initiate a dispensing operation. Thus, if a child or inexperienced user simply inserts a hand, rather than a container, into dispenser well  63 , water will not be dispensed from dispenser assembly  40  and fall onto a kitchen floor surface. 
     At this point, it should be understood that the present invention provides for an easily manufactured and efficient passive sensor array that automates a refrigerator dispenser assembly. The sensor array in accordance with present invention, not only serves to automatically initiate a dispensing operation upon sensing the presence of a container, but detects a location of an upper rim portion of the container and fills the container to a level below the rim. In addition, by being able to differentiate between animate and inanimate objects, the present invention automatically creates a “child lock-out” feature which operates continuously without creating an inconvenience for other users. Finally, by employing passive sensors instead of active sensors, power requirements for the dispensing assembly are reduced, along with the number of components necessary to activate and control the dispensing of water and/or ice cubes from the dispenser. 
     Although described with reference to a preferred embodiment of the invention, it should be readily understood that various changes and/or modifications can be made to the invention without departing from the spirit thereof. For instance, while the invention is shown with two sensor strips each having eight sensors, various other configurations can also be employed. Also, while described as employing capacitive-type sensors, other forms of passive sensors could also be utilized. In general, the invention is only intended to be limited by the scope of the following claims.