Abstract:
The invention relates to an automated liquid dispenser employing ultrasonic sensing to determine the level of a dispensed liquid with respect to the height of a container to be filled. In one aspect, the invention relates to a refrigerator with an automated liquid dispenser that utilizes ultrasonic sensing.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     In one aspect, the invention relates to automated liquid dispensers and more particularly to automated liquid dispensers that sense the level of a dispensed liquid with respect to the height of a container to be filled to prevent overfilling. In another aspect, the invention relates to a refrigerator incorporating an automated liquid dispenser. 
     2. Description of the Related Art 
     Contemporary refrigerators commonly have a water/beverage dispenser located in the door of the refrigerator for the external dispensing of liquid, usually chilled water, from the refrigerator. An ice dispenser often accompanies the liquid dispenser. Illustrative dispensers are shown in U.S. Pat. Nos. 6,425,425; 5,551,598; and 4,807,086, which are incorporated by reference. 
     Some dispensers are activated via a pressure-sensitive switch that is depressed by a container, such as a cup or glass, when it is inserted into the dispenser. Others employ buttons that a user continuously pushes until the desired amount of water has been dispensed. Both of these systems require a user to remain at the refrigerator to either hold the container in place or to push the buttons during dispensing. Additionally, dispensing can be undesirably interrupted and take longer than necessary if the user is unable to continuously activate the dispenser. 
     A known problem of such dispensers is that inattentive users can overfill the container, resulting in the spilling of the liquid onto the refrigerator or surrounding floor. It is desirable to provide the dispenser with overfill protection that stops the dispensing of the liquid regardless of the user input. 
     Overfill protection systems are known and many work fairly well for their intended purpose. Most of the known overfill protection systems rely on a plurality sensors to sense the container height and the liquid level. The use of a plurality of sensors increases the cost of the system. In a commodity market like household refrigerators, the additional cost attributable to the plurality of sensors is highly undesirable. There is a continuous need in this market for properly functioning systems with reduced cost. 
     SUMMARY OF THE INVENTION 
     In one aspect, the invention relates to an automated liquid dispenser for dispensing a liquid into an open-top container comprising a housing defining a dispensing zone for receiving the open-top of the container, a liquid dispensing spout extending from the housing and above the dispensing zone for dispensing liquid into the container, and first and second reflector arrays disposed on opposite sides of the dispensing zone such that the open-top container is between the first and second arrays when the open-top container is received within the dispensing zone. Each reflector array comprises multiple vertically spaced reflectors, with a reflector on the first array being paired with a reflector on the second array. An emitter is mounted in a position to emit a signal onto the multiple reflectors of the first reflector array for reflection across the dispensing zone and onto the corresponding paired reflectors of the second array, and a receiver is mounted in a position to receive the emitted signal reflected from the reflectors of the second array and generate a container height signal. Additionally, the dispenser comprises a liquid level sensor for determining the liquid level in the container and generating a liquid level signal and a controller coupled to the receiver and the liquid level sensor for controlling the filling of the liquid into the container based on the received container height signal and the liquid level signal. 
     The first and second reflector arrays can be removably mounted to the housing. Further, the first reflector array can be carried by a first panel and the second reflector array can be carried by a second panel, wherein the first and second panels are removably coupled to the housing. The reflectors can be integrally formed with the panels and are preferably molded from a thermal plastic material. 
     The reflectors are disposed at a predetermined angle relative to a plane orthogonal to the emitted signal such that the emitted signal is reflected from the reflectors of the first array horizontally across the dispensing zone, onto the paired reflectors of the second array, and then onto the receiver. The predetermined angle for the reflectors of the first array is preferably 45-degrees relative to a plane orthogonal to the emitted signal, and the predetermined angle for the reflectors of the second array is preferably −45 degrees relative to a plane orthogonal to the emitted signal. 
     The reflectors in each array are arranged in a step configuration with a vertical offset and a lateral offset between adjacent reflectors, wherein the vertical offset can be between 0.75 and 2 inches and the lateral offset can be 0.25 to 1.00 inches. 
     The liquid level sensor is a wide bandwidth transducer, such as a piezo film or a micro-electro-mechanical system (MEMS). 
     The container height signal is composite signal of all the signals reflected across the dispensing zone and not blocked by the open-top container. 
     In another aspect, the invention relates to a refrigerator in combination with a liquid dispenser for dispensing a liquid into an open-top container, wherein the refrigerator comprises a cabinet having at least one refrigerated compartment with an open face and a door movably mounted to the refrigerated compartment for movement between a closed position, where the door covers the open face, and an open position, where the door is withdrawn from the open face. The liquid dispenser in combination with the refrigerator comprises a housing located in a recess in the door and defining a dispensing zone for receiving the open-top of the container. A liquid dispensing spout extends from the housing and above the dispensing zone for dispensing liquid into the container. First and second reflector arrays are disposed on opposite sides of the dispensing zone such that the open-top container is between the first and second arrays when the open-top container is received within the dispensing zone, and each reflector array comprises multiple vertically-spaced reflectors, with a reflector on the first array being paired with a reflector on the second array. An emitter is mounted in a position to emit a signal onto the multiple reflectors of the first reflector array for reflection across the dispensing zone and onto the corresponding paired reflectors of the second array, and a receiver is mounted in a position to receive the emitted signal reflected from the reflectors of the second array and generate a container height signal. Additionally, the dispenser comprises a liquid level sensor for determining the liquid level in the container and generating a liquid level signal and a controller coupled to the receiver and the liquid level sensor for controlling the filling of the liquid into the container based on the received container height signal and the liquid level signal. 
     The first and second reflector arrays can be removably mounted to the housing. Furthermore, the first reflector array can be carried by a first panel and the second reflector array can be carried by a second panel, wherein the first and second panels are removably coupled to the housing. The housing comprises opposing sides, with each side having a channel, and the panels are received within the channels to mount the panels to the housing. The reflectors can be integrally formed with the panels and are preferably molded from a thermal plastic material. 
     The housing further comprises an upper wall spanning the side walls, and the emitter, receiver, and liquid level sensor are mounted to the upper wall. The dispensing spout extends through the upper wall. 
     The reflectors are disposed at a predetermined angle relative to a plane orthogonal to the emitted signal such that the emitted signal is reflected from the reflectors of the first array horizontally across the dispensing zone, onto the paired reflectors of the second array, and then onto the receiver. The predetermined angle for the reflectors of the first array is preferably 45 degrees relative to a plane orthogonal to the emitted signal, and the predetermined angle for the reflectors of the second array is preferably −45 degrees relative to a plane orthogonal to the emitted signal. 
     The reflectors in each array are arranged in a step configuration with a vertical offset and a lateral offset between adjacent reflectors. The vertical offset can be between 0.75 and 2 inches, and the lateral offset can be 0.25 to 1.00 inches. 
     The liquid level sensor is a wide bandwidth transducer, such as a piezo film or a micro-electro-mechanical system (MEMS). 
     The container height signal is composite signal of all the signals reflected across the dispensing zone and not blocked by the open-top container. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a perspective view of a refrigerator with an in-the-door automatic liquid dispenser according to the invention comprising a housing received within a recess in the door. 
     FIG. 2 is a perspective view of the housing of FIG. 1, carrying first and second panels to which are mounted first and second reflector arrays used to determine the location of the top of a container. 
     FIG. 3 is a perspective view of the first panel and the first reflector array in FIG.  2 . 
     FIG. 4 a  is a schematic view of the automatic liquid dispenser of FIG. 1 illustrating a controller and sensors for determining the container top and the liquid level, including an emitter and receiver and the transit path of the signals sent from the emitter, reflected by reflectors, and received by a receiver. 
     FIG. 4 b  is a schematic view identical to FIG. 4 b , except with a container partially filled with liquid disposed between the first and second reflector arrays and showing emission and reflection paths of signals emitted from the emitter for determining the position of the top of the container and from a transducer for determining the liquid level. 
     FIG. 5 is a schematic view of a signal from the emitter, the signal as received by a receiver when no container is disposed in the housing, and the signal as received by the receiver when the container in FIG. 4 b  is disposed in the housing. 
    
    
     DESCRIPTION OF THE INVENTION 
     Referring now to the figures, and FIGS. 1-3 in particular, a refrigerator  1  is illustrated with an automatic liquid dispenser  10  in accordance with the invention. The refrigerator  1  is of conventional construction and comprises a cabinet  2  divided into a refrigerator compartment  3  and a freezer compartment  4 , both of which have an open face that is selectively closed by a corresponding door  5 ,  6 . A conventional refrigeration system is utilized to send chilled air into both compartments  3 ,  4 . 
     The dispenser  10  is positioned within one of the doors  5 ,  6 . As illustrated, the dispenser  10  is positioned within the door  6  covering the freezer compartment  4 . However, the dispenser could be located in either door. The dispenser is similar in shape, size, and general appearance to conventional refrigerator door dispensers and is located within a recess formed in the door  6 . 
     Referring to FIGS. 1 and 2, the dispenser  10  comprises a housing  14  that is positioned within the recess formed in the door  6 . The housing  14  provides support or an interface for the various components forming the dispenser  10 . For example, a dispensing spout  16  projects through and is guided by a top wall  27  of the housing  14 . In addition to the top wall  27  (which is not shown in FIG.  2 ), the housing  14  has parallel first and second side walls  20 ,  22 , a rear wall  24  connecting the rear edges of the side walls  20 ,  22 , and a bottom wall  26  connecting the bottom edges of the side walls  20 ,  22 . The side walls  20 ,  22  each have a vertical channel  34  that generally extends from the top wall  27  to the bottom wall  26 . The housing  14  defines an open-faced recess  28  for receiving therein at least a portion of a container to be filled, and the open face of the recess  28  is substantially coincident with the outer surface of the refrigerator door  6  when the dispenser  10  is located in the refrigerator  1 . If the container is completely disposed inside the recess  28 , the container can set upon the bottom wall  26  of the housing. 
     The recess  28  defines a dispensing zone in which an open-top container can be received for filling from the dispensing spout  16 . As illustrated, the dispensing spout  16  is preferably positioned above and centered relative to the width of the dispensing zone such that the dispensing spout  16  is generally aligned with the center of a container that is properly placed within the dispensing zone. A valve  56 , for example a solenoid valve, shown schematically in FIGS. 4 a  and  4   b , controls, i.e. turns on and off, the dispensing of liquid through the spout  16 . Dispensing spouts and valves are well known in the field and are not germane to this invention. 
     The dispensing zone need not be coincident with the recess  28 . It is within the scope of the invention for the dispensing zone to be formed by a portion of the recess  28 . This is especially true when the dispenser  10  includes an ice cube dispenser, which dispenses into the recess. 
     The dispenser  10  further comprises first and second reflector arrays  36 ,  38  removably mounted to the first and second side walls  20 ,  22 , respectively, on opposite sides of the dispensing zone. The arrays  36 ,  38  have a vertical stair-step structure with an individual reflector  40   a - 40   e  located at each step, wherein the reflectors  40   a - 40   e  are vertically and laterally offset relative to each other so that at least a portion of a reflector extends vertically below and horizontally beyond the reflector disposed thereabove. The vertical and lateral offsets are defined as the distances between the horizontal centerlines and vertical centerlines, respectively, of the reflectors  40 . The vertical offset between each reflector  40  is preferably constant and between 0.75 and 2 inches, depending on the desired container height resolution. A smaller distance between the reflectors  40  corresponds to a finer resolution. Although each array  36 ,  38  can have any suitable number of reflectors  40 , each array  36 ,  38  preferably comprises five reflectors  40 ; therefore, the total height of the array  36 ,  38  measured from the lowest reflector to the highest reflector, can range from 3 to 8 inches. The lateral offset between each reflector is also preferably constant and can range between 0.25 and 1.00 inches. The reflectors  40  are preferably composed of a thermal plastic. 
     The reflectors  40   a - 40   e  of the arrays  36 ,  38  are arranged in corresponding pairs. That is, reflector  40   a  of the array  36  corresponds with reflector  40   a  of array  38 . Each reflector  40  is oriented at an angle, preferably either a −45-degree angle or a 45-degree angle, relative to the side walls  20 ,  22  so that the reflectors  40  in the first array  36  are facing those of the second array  38  and the reflectors of the second array  38  are facing those of the first array  36 . 
     As shown in FIG. 2 and 3, the arrays  36 ,  38  are carried by first and second plates  30 ,  32 . Optionally, the arrays  36 ,  38  can be integral with the first and second plates  30 ,  32 . The arrays  36 ,  38  are oriented in a plane parallel to the plane of the plates  30 ,  32  and parallel to the plane of the side walls  20 ,  22 ; however, the arrays  36 ,  38  are not limited to the parallel arrangement and can be mounted perpendicular or at an angle between parallel and perpendicular to the side walls  20 ,  22 . The plates  30 ,  32  are removably coupled to the side walls  20 ,  22  via the channels  34 . In this configuration, the plates  30 ,  32  are inserted into their respective channels  34  at the upper end of the housing  14  and slid into place. The plates  30 ,  32  can also be retained by other means, such as a snap fit, a press fit, fasteners, or clamps. Rather than being carried by plates, the arrays  36 ,  38  can alternatively be integral to the housing  14 . 
     Referring now to FIG. 4 a , the automatic liquid dispenser  10  further comprises an ultrasonic emitter  42  and an ultrasonic receiver  44  disposed above first and second reflector arrays  36 ,  38 , respectively, and preferably in the line of sight of each reflector  40  on the respective arrays  36 ,  38 . When the emitter  42  emits a signal, all reflectors  40  in the first array  36  receive the signal because of the lateral offset and, in turn, reflect the signal. Because the first reflector  40   a  is nearest the emitter  42 , it receives and reflects the signal first. Similarly, the farthest reflector  40   e  receives and reflects the signal last. Given that the reflectors  40  are oriented at a 45-degree angle relative to the side walls  20 ,  22  and relative to a plane orthogonal to the signal, the emitted signal is reflected across the dispensing zone towards the reflectors  40  of the second array  38 . The signal reflected from reflector  40   a  of the first array  36  is the earliest to be received and reflected by the second array  38 , in particular by reflector  40   a  of the second array  38 . Likewise, the signal reflected from reflector  40   e  of the first array  36  is the last to be received and reflected by the second array  38 , in particular by reflector  40   e  of the second array  38 . The receiver  44  receives the signal reflected by the second array  38  in a series of pulses because the length of the signal transit path and, therefore, the transit time increase as the distance between the reflectors  40  and the emitter  42 /receiver  44  increases. As shown in FIG. 5, the emitted signal  46  is a single pulse while the received signal  48  is a composite of a series of pulses, each of which corresponds to reflection from one of the sets of reflectors  40 . The number of pulses, in turn, corresponds to a vertical location in the housing  14 . 
     It is possible that a signal reflected from one reflector  40  in the first reflector array  36  might diverge and contact more than one reflector  40  in the second reflector array  38 . Preferably, the arrays  36 ,  38  are designed to avoid this situation; however, if it is not possible to design around diverging signals, the position of the top of the container within the housing  14  can be determined from the length of the received signal and not the number of pulses in the received signal. 
     To monitor the liquid level in the container, the dispenser  10  comprises a liquid level sensor, such as an ultrasonic transducer  52 , positioned above the opening of the container and near the spout  16 . The transducer  52  emits a signal towards the interior of the container, and the signal reflects off the surface of the liquid if there is liquid inside the container or either the bottom wall  26  of the housing  14  or the bottom of the container if no liquid is present in the container. Preferably, the dispenser utilizes a single transducer  52  that reconfigures into a receiver after a signal is emitted, but the transducer can also be an emitter/receiver pair. After the signal is reflected, it is received by the transducer  52 . 
     Because the transducer  52  is positioned close to the reflecting surface and has to quickly reconfigure from/to a receiver, it is preferably a wide bandwidth transducer, also knows as a “low Q” transducer, such as a piezo film or a micro-electro-mechanical (MEMS) device. Vibrations in wide bandwidth transducers dampen rapidly after signal emission; thus, the transducers are able to quickly reconfigure and receive the reflected signal. 
     The automatic liquid dispenser  10  further comprises a controller  54  that is in communication with the emitter  42 , the receiver  44 , the transducer  52 , and the valve  56 . The controller  54  instructs the emitter  42  when to emit a signal, receives signals from the receiver  44 , and receives signals from the transducer  52 . The controller  54  analyzes the received signals to calculate the relative positions of the top of the container and the level of liquid within the container. 
     In operation, the controller  54  instructs the emitter  42  to periodically emit a pulse signal like the signal  46  in FIG.  5 . If there is no obstruction to the signal path, as in FIG.  4   a , the receiver  44  receives a signal having as many pulses as there are reflector pairs. For example, the signal  48  in FIG. 5 has five pulses that correspond to the five reflector pairs in FIG. 4 a . The receiver  44  converts the received signal to an output signal having an appropriate format, such as digital or analog, and sends the output signal to the controller  54 . The controller  54  analyzes the signal and determines that there is no container in the dispensing zone. 
     When a user inserts at least the open top of a container into the dispensing zone, the container obstructs the path between the first and second reflector arrays  36 ,  38  such that signals reflected by the reflectors  40  on the first array  36  below the top of the container do not reach the second reflector array  38  and are not received by the receiver  44 . For example, when the container in FIG. 4 b  is inserted into the dispenser  10 , the container impedes signals reflected from reflectors  40   c ,  40   d , and  40   e  of the first array  36  and prevents the signals from reaching reflectors  40   c ,  40   d , and  40   e  of the second array  38 . As a result, the signal received by the receiver  44  comprises a number of pulses corresponding to the number of reflector  40  pairs located above the top of the container. As depicted in FIG. 5, the signal  50  received by the receiver  44  in FIG. 4 b  comprises two pulses received from reflectors  40   a  and  40   b  of the second array  38 . Once all of the pulses in the signal  50  are received, the receiver  44  converts the signal  50  to a container height signal and sends the container height signal to the controller  54 . 
     After the controller  54  receives the signal, the controller  54  detects that the container height signal is different than the unobstructed signal and determines that a container is positioned in the dispensing zone. As a result, the controller  54  determines from the number of pulses in the container height signal the location of the top of the container within the housing  14 , engages the transducer  52  to monitor the liquid level in the container, and optionally, turns on a dispenser light (not shown). The transducer  52  sends a signal that is initially reflected by either the bottom wall  26  of the housing  14  or the bottom wall of the container and receives and converts the signal into a liquid level signal that contains information about the location of the surface of the liquid within the dispenser. 
     Next, the transducer  52  communicates the container height signal to the controller  54 , and the controller  54 , having determined that no liquid is present in the container, begins dispensing liquid through the spout  16  by opening the valve  56 . The transducer  52  sends and receives signals that are reflected by the surface of the liquid in the container. These signals are subsequently converted in to liquid level signals and communicated to the controller  54 . As the container is filled, the time required for the signal to travel from and return to the transducer  52  is reduced; therefore, a shorter transit time corresponds to a higher liquid level. 
     The controller  54  regulates the filling of the container by comparing the container height signal to the liquid level signal, which is continuously changing, to determine when the liquid has reached a desired level relative to the position of the top of the container. For example, if the container is to be almost completely filled, the controller  54  might stop the dispensing of liquid by closing the valve  56  when the liquid level is a certain distance below the top of the container or has reached a height corresponding to a certain percentage, for example 95%, of the container height. Similarly, if the container is to be half filled, the controller  54  can stop the dispensing of liquid when the liquid level has reached a height corresponding to 50% of the container height. The controller  54  can be programmed for several dispensing levels and can have a default level. If the default level is not desired, the preferred level can be selected through user-operated controls, such as buttons or digital displays, on the dispenser  10 . Once the container is filled to the desired level and the valve  56  has been closed, the user removes the filled container from the dispensing zone. 
     Although the dispenser  10  has thus far been described in conjunction with ultrasonic signals, it is within the scope of the invention to utilize other types of signals. It is, however, necessary that the container is not transparent to the signals and can act as a barrier to signal transmission. Furthermore, the dispenser  10  is not limited to use in a refrigerator. The dispenser can be employed in a restaurant beverage dispenser, a portable liquid storage and dispensing cooler, or any other relevant application. 
     The current invention provides an automated liquid dispenser that prevents overfill of a container and does not require the user to remain at the dispenser. Additionally, the reflector arrays have a simple design and comprise few parts, thus reducing the likelihood of mechanical or structural failure. In the exceptional case that the reflector arrays need to be replaced or repaired, they are easily removable from the housing. The dispenser is cost efficient because it requires only one emitter/detector pair to determine the height of the container. Furthermore, since the glass height system uses known transit path lengths, it can be utilized to calibrate the water height system if needed, for example if the speed of the ultrasonic signals changes due to temperature. 
     While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit.