Patent Publication Number: US-10322416-B2

Title: Method and system for upper pill-crushing-cup detection

Description:
TECHNICAL FIELD 
     This application relates to pill crushing. More particularly, this application relates to a method and system for detecting an upper cup that is placed in a lower cup containing a pill to be crushed by machine, and preventing operation of the machine unless the upper cup is detected. 
     BACKGROUND 
     Often patients have difficulty swallowing medications in tablet or pill form; however for many medications, this is the only form in which it is available. Also, many pills come with coatings or are otherwise designed to break down after ingestion, but in cases where patients are very young, elderly, and/or ill this breakdown of medication is disrupted and either occurs much slower than desired or not at all. In order to more easily and effectively administer medications in such cases, pills are often comminuted with a mortar and pestle or other mechanical device that generally crushes and/or grinds the pill between two hard surfaces. Once the pills are comminuted the powder is generally transferred to a container where it is mixed with fluid or food for administering to a patient. 
     In order to reduce cross-contamination and material loss, pairs of inexpensive, single use, nesting containers are used to comminute one or more pills between the bottoms of the nesting containers. These containers can then be separated and the comminuted medication can then be scraped and mixed or suspended in a fluid or food for administering to a patient. 
     When a machine is used to comminute the medication, it is often easy for the operator of the machine to forget to place the upper cup in place over the lower cup containing the medication. As a result, when the medication is crushed it creates a mess that is difficult to clean up, and to clean up safely. Furthermore, the machine can create toxic airborne dust, there can be a loss of dosage of the medication, and there can be cross-contamination between the medications given to different patients if the crushing chamber of the machine is not thoroughly cleaned. On top of this, it causes down-time and delays in a care-giver&#39;s schedule. The outcome of not placing a second cup on top of the pills in the first cup is therefore costly and hazardous. 
     This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention. 
     SUMMARY OF INVENTION 
     The present invention is directed to a method and system for use in a pill-crushing machine, which incorporates a sensor for detecting the presence of an upper cup over a lower cup containing one or more pills. The sensor sends a signal that prevents operation of a crushing mechanism unless the upper cup is detected. 
     A further, optional sensor may detect when a drawer carrying the cups is fully inserted into the machine, this further sensor producing a signal that only allows operation of the crushing mechanism when the drawer is fully inserted. For operation of the mechanism, both the upper cup must be present and the drawer must be closed. 
     Disclosed herein is a system for controlling operation of a pill-crushing mechanism, the system comprising a cup holder configured to hold a lower cup with one or more pills therein and an upper cup nestled in the lower cup over said pills; a sensor located in relation to the cup holder so that the sensor has a first state that corresponds to an absence of the upper cup from the cup holder and a second state that corresponds to a presence of the upper cup in the cup holder, nestled in the lower cup over said pills; and a controller that receives signals from the sensor corresponding to said states, wherein the controller prevents operation of a mechanism for crushing said pills when the sensor is in the first state and enables operation of the mechanism when the sensor is in the second state. 
     Some embodiments of the system may comprise a source of electromagnetic radiation positioned so that: the source directs said radiation onto the sensor when the upper cup is absent from the cup holder; and the radiation is blocked from being incident upon the sensor when the upper cup is present over the pills in the lower cup in the cup holder; wherein the sensor is sensitive to said radiation. 
     In some embodiments, the source and sensor are positioned so that: the radiation passes above the lower cup when the lower cup is present in the cup holder and the upper cup is absent from the cup holder; and the radiation is blocked from being incident upon the sensor by a wall of the upper cup when the upper cup is present over the pills in the lower cup in the cup holder. 
     Some embodiments of the system may include a drawer in which is mounted the cup holder, wherein the drawer slides into and out of a pill-crushing machine that comprises the mechanism. Some embodiments of the system may further comprise a laser diode positioned so that: the laser diode directs radiation onto the sensor along a path that is above the lower cup when the lower cup is present in the cup holder and the upper cup is absent from the cup holder; and the radiation is blocked from being incident upon the sensor by a wall of the upper cup when the upper cup is present over the pills in the lower cup in the cup holder; wherein the sensor is sensitive to the radiation; and wherein the path is nearer to an inner edge of the cup holder than an outer edge of the cup holder such that the drawer must be substantially closed for the wall of the upper cup to block the path. 
     Further disclosed herein is a system for controlling operation of a pill-crushing mechanism, the system comprising: a drawer that slides into and out of a pill-crushing machine that comprises the pill-crushing mechanism; a cup holder mounted in the drawer and configured to hold: a lower cup with one or more pills therein; and an upper cup nestled in the lower cup over said pills; a sensor located in relation to the cup holder so that the sensor has: a first state that corresponds to an absence of the upper cup from the cup holder; and a second state that corresponds to a presence of the upper cup nestled in the lower cup over said pills; a magnet mounted in the drawer; and a magnetic sensor mounted in the machine so that it: detects the magnet when the drawer is closed; and does not detect the magnet when the drawer is not closed; and a controller that receives signals from the sensor that are representative of the sensor&#39;s state, and further signals from the magnetic sensor that are representative of whether the drawer is closed, wherein the controller: prevents operation of the mechanism when the sensor is in the first state or when the drawer is not closed; and enables operation of the mechanism when both the sensor is in the second state and the drawer is closed. 
     Still further disclosed is a method for controlling operation of a pill-crushing mechanism, comprising the steps of: locating a sensor in relation to a cup holder so that the sensor has: a first state that corresponds to an absence of an upper cup from a lower cup being held by the cup holder; and a second state that corresponds to a presence of the upper cup nestled in the lower cup over one or more pills in the lower cup; detecting, by the sensor, whether the upper cup is nestled in the lower cup over the one or more pills therein; receiving, by a controller, a first signal from the sensor when the sensor is in the first state; preventing, by the controller, operation of a mechanism for crushing said pills in response to the first signal; receiving, by the controller, a second signal from the sensor when the sensor is in the second state; and enabling, by the controller, operation of the mechanism when the sensor in response to the second signal. 
     In some embodiments, the method further comprises: emitting electromagnetic radiation from a source; directing said radiation onto the sensor when the upper cup is absent from the lower cup being held by the cup holder; and blocking said radiation from being incident upon the sensor by the upper cup when the upper cup is present over the pills in the lower cup; wherein the sensor is sensitive to said radiation. 
     In some embodiments, the method further comprises: detecting whether a drawer holding the lower cup, the pills and the upper cup is closed in a machine comprising the pill-crushing mechanism; preventing operation of the mechanism when the drawer is not closed; and detecting, before the enabling step is undertaken, that the drawer is closed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The following drawings illustrate embodiments of the invention, which should not be construed as restricting the scope of the invention in any way. 
         FIG. 1  is a schematic diagram showing a front view of the main elements of the system, according to an embodiment of the present invention. 
         FIG. 2  is a partial cross-section drawing of a pill-crushing machine including the system according to an embodiment of the present invention, with only a lower cup inserted. 
         FIG. 3  is a partial cross-section drawing of a pill-crushing machine including the system according to an embodiment of the present invention, with both lower and upper cups inserted. 
         FIG. 4  is a schematic diagram of the system showing a top view of the main elements of the system including an optional closed-drawer detector, according to an embodiment of the present invention. 
         FIG. 5  is a perspective view of a drawer including magnet and bolt hole, according to an embodiment of the present invention. 
         FIG. 6  is a flowchart of a method for preventing operation of a pill-crushing mechanism unless an upper cup is placed over medication present in a lower cup, according to an embodiment of the present invention. 
         FIG. 7  is a flowchart of additional method steps for preventing operation of a pill-crushing mechanism unless a cup-holding drawer is placed fully into the crushing machine, according to an embodiment of the present invention. 
         FIG. 8  is a flowchart of additional method steps for preventing opening of a cup-holding drawer until a pill-crushing mechanism has stopped operating, according to an embodiment of the present invention. 
     
    
    
     DESCRIPTION 
     A. Glossary 
     The term “comminution” refers to the crushing of pills into powder form. 
     The term “system” when used herein refers to a system for detecting an upper cup that is placed in a lower cup containing a pill to be crushed by machine, and preventing operation of the machine unless the upper cup is detected. 
     The term “operator” or “user” refers to a person who uses a pill-crushing machine to crush pills. 
     B. Industrial Applicability 
     The method and system of the present invention are useful for safely crushing pills between two cups in a pill-crushing machine. It prevents mess and wastage of medication, reduces the chance of cross-contamination, reduces potentially toxic airborne medication dust, and saves time. 
     C. Overview 
     Referring to  FIG. 1 , there is shown an overview of the main components of the system  10  for preventing operation of a pill-crushing mechanism unless it is safe to do so. The system  10  forms part of a pill-crushing machine, and includes a cup holder  12 , into which is placed a lower cup  14 . One or more pills  16  are placed into the lower cup  14  and an upper cup  18  is then nestled inside the lower cup and placed over the pills. A laser  20  is positioned relative to the cup holder  12  such that the laser beam  21  produced by the laser is directed over the lip  24  of the lower cup  14 , when the lower cup is properly placed in the cup holder, as shown, and when there is no upper cup  18  present. A sensor  22  is positioned relative to the cup holder  12  such that it can detect the laser beam  21  emitted by the laser  20  when the lower cup  14  is properly in position in the cup holder, and when there is no upper cup present. The positions of the laser  20  and sensor  22  relative to the cup holder  12  are also such that, when the upper cup  18  is present, its wall  29  blocks the path of the laser beam  21  between the laser  20  and sensor  22 . To achieve this, the laser  20  is located such that the laser beam  21  is below the level of the lip  28  of the upper cup  18  if the upper cup were present over pills  16 . 
     As a consequence of the relative positioning and orientation of the laser  20 , sensor  22  and cup holder  12 , the sensor has at least two states corresponding to the two different levels of laser light detected, which result from the upper cup  18  being present or not. The sensor  22  sends the signals to the control module  30 , which controls operation of the pill-crushing mechanism. If the sensor  22  detects the laser beam  21 , then the signal sent to the control module  30  effectively instructs it to prevent operation of the pill-crushing mechanism. If the sensor  22  detects absence of the laser beam  21 , or a significant reduction in intensity of laser light, then the signal sent to the control module  30  effectively instructs it to enable operation of the pill-crushing mechanism. Once the operation of the pill-crushing mechanism is enabled, a user of the pill-crushing machine is then able to start the pill crushing by pressing a start button. 
     As can be seen from  FIG. 1 , the height of the laser beam  21  needs to be only just above the upper surface of the lip  24  of the lower cup  14 . This can be calculated by taking into account the thickness of the lip  24  of the lower cup  14 . The beam  21  should not be so low as to be blocked by an extra cup that is placed over the first cup  14  without any pills present in the first cup, just in case two lower cups are used by accident. As an example, the laser  20  may be positioned so that the center of the laser beam  21  is at a height of 2 mm above the upper surface of the cup holder  12 . This will not be blocked by a single lower cup  14  having a lip  24  that is 0.7 mm thick, or even two lower cups, but it will be blocked by a combination of a lower cup (lip 0.7 mm), small pill (1.5 mm thick) and upper cup (lip 0.7 mm), which would have a total height of about 3 mm. Obviously the laser beam will be blocked if larger pills are crushed. The positioning of the laser  20  and sensor  21  relative to the cup holder  12  will therefore depend on the dimensions of the cups that are to be used, and the pills that are to be crushed, and the relative positioning may be different in other embodiments. 
     As an example, the laser  20  may be a 650 nm red diode laser and the sensor may be a photodiode with sensitivity in the visible and near infrared spectrum. Since the laser beam  21  diverges, spurious reflections may be present inside the crushing chamber, and so the sensor  22  may always detect some amount of laser light even if the main beam  21  is directly blocked. Depending on the type of material of the cups  14 ,  18 , which is typically plastic, and thickness of the cup walls, some of the laser light may be transmitted through the cups, but the amount transmitted will be measurably less than the unblocked laser beam. The detection of the spurious or transmitted laser light can be used as a test to ascertain that the laser  21  is functioning properly, or that it has not been deliberately blocked to circumvent the safety feature that it brings to the pill-crushing machine. 
     The control module  30  is built using known components and techniques. Other control modules for pill-crushing mechanisms already exist. The added features in control module  30  compared to known control modules are (a) the prevention of operation of the pill-crushing mechanism when the sensor detects a high intensity of laser light, i.e. an intensity above a predetermined threshold and (b) the enablement of operation of the pill-crushing mechanism when the sensor detects a low intensity of laser light, i.e. an intensity below the same or a lower predetermined threshold, which would of course include detecting no laser light. 
     D. Exemplary Embodiment 
     Referring to  FIG. 2 , a pill-crushing machine  32  is shown embodying the system  10  of the present invention. The components of the machine  32  that are shown include a bottom housing  34  and a front housing  36 . Also shown is a drawer  40  in which is mounted the cup holder  12 . The drawer  40  slides into and out of the machine  32  on runners  42  at the bottom of the drawer. The direction the drawer  40  slides is perpendicularly into and out of the plane of the drawing. The drawer  40  slides into a crushing chamber  44  within the machine  32 . At the bottom of the crushing chamber  44  are steps  46 , the insides of which serve to guide the runners  42  of the drawer  40 , which slide on the upper surface of baseplate  48 . 
     The laser  20  produces laser beam  21 , which is detected by sensor  22  when only the lower cup  14  is present. The laser beam  21  is shown to pass above the upper surface  50  of the lip of the lower cup  14 . 
     The top of the crushing chamber  44  is fitted with a cover  52 , through which the drive shaft  54  of the pill-crushing mechanism passes. The drive shaft  54  forms part of the pill-crushing mechanism and is controlled by the control unit  30 . At the base of the drive shaft  54  is a pressure plate  56  for imparting pressure to and rotating the base of the upper cup when present, while the cup holder  12  retains the lower cup  14  stationary. When there is only the lower cup  14  present, the overall height of the contents of the cup holder  12  is not enough to block the laser beam  21  and the signal sent from the sensor  22  to the control module  30  is such that the crushing process cannot be performed. 
     The laser  20  is a 650 nm red diode laser model RLD650005 from Dongguan Yuquan Electronics Co. Ltd. and the sensor  22  is a BPW34 photodiode from Vishay Semiconductors. Other laser diodes and photodiodes may be used in other embodiments, and the wavelength may be a different wavelength, which may be in the visible or non-visible spectrum. 
     Referring to  FIG. 3 , the pill-crushing machine  32  is shown with both a lower cup  14  and an upper cup  18 , with a pill  16  between the two. The upper surface  60  of the upper cup  18  is shown to be above the height of the laser beam  21 . The laser beam  21  is therefore blocked by the wall  29  of the upper cup  18  so that it does not directly illuminate the sensor  22 . As a result, the signal sent from the sensor  22  to the control module  30  is such that operation of the pill-crushing mechanism is enabled. When in the enabled state, the pill-crushing mechanism can be started by the user activating a button or switch, causing the drive shaft  54  and pressure plate  56  to lower in the direction of the arrow  62  into the upper cup  18  and rotate it relative to the lower cup  14 . The relative rotation of the two cups  14 ,  18  and the pressure between them causes the pill  16  to be crushed into powder. Physical relief features (not shown) on the bases of the cups  14 ,  18  assist in the crushing process. 
       FIG. 4  shows a top view of a system  62  for safely operating a pill-crushing mechanism. The laser  20  and sensor  22  are located so that the laser beam  21  sections the wall  70  of the lower cup  14  when viewed from above. Provided that enough of the wall is sectioned, it follows that the upper cup  18 , when placed in the lower cup  14 , will block the laser beam  21 . Since the laser beam  21  is arranged to section the innermost portion of the cup wall  70 , i.e. the portion of the wall farthest from the front, outer edge  71  of the drawer  40 , the drawer must be fully, or at least sufficiently, inserted as well as having an upper cup  18  present in order for the laser beam  21  to be blocked. As a result, the pill-crushing mechanism is only enabled if two conditions are satisfied, these being (a) two cups  14 ,  18  are used with one or more pills  16  therebetween; and (b) the drawer  40  is fully inserted into the pill-crushing machine  32 . 
     In other embodiments, the laser  20  and sensor  22  may be aligned to be diametrically opposite the cup holder  12  from each other, or they may be located closer to the front  71  of the drawer  40 . 
     E. Variations 
     Still referring to  FIG. 4 , system  62  includes two further safety features that contribute to the safe operation of the pill-crushing mechanism. The first is the secondary detection that the drawer  40  is fully inserted into the pill-crushing machine. This is achieved by the inclusion of a magnet  72  that is mounted in the drawer  40 . When the drawer  40  is fully inserted, it butts up against a backstop  74  (for example), on which is mounted a reed switch  76 . When the drawer  40  is butted up against the backstop  74 , the magnet  72  is close enough to the reed switch  76  to activate it. Activation of the reed switch  76  is detected by the control module  30 . When the reed switch  76  is not activated, the control module  30  prevents operation of the pill-crushing mechanism. When the reed switch  76  is activated, the operation of the pill-crushing mechanism is enabled so that it can be started by a user of the pill-crushing machine. The control unit  30  is configured to enable operation of the pill-crushing mechanism when both the reed switch  76  is activated and when the sensor  22  detects the presence of an upper cup  18 , simultaneously. The control unit  30  is also configured to prevent operation of the pill-crushing mechanism when either the reed switch  76  is not activated or when the upper cup  18  is not detected. A magnetic sensor other than a reed switch may be used in other embodiments. 
     The second further safety feature is an interlock, i.e. the locking of the drawer  40  in its fully inserted position while the pill-crushing mechanism is operating. To achieve this, a solenoid  80  is mounted in the pill-crushing machine by the side of the drawer  40 . The core  82  of the solenoid  80  acts as a bolt that is inserted into a bolt hole  84  on the side of the drawer  40  when the solenoid is activated. The bolt  82  prevents the drawer  40  from opening when it is inserted into the bolt hole  84 . The solenoid  80  is activated when the operator of the pill-crushing machine starts the pill-crushing process by pushing button  86 , and is deactivated when the pill-crushing mechanism stops. When the solenoid  80  is deactivated, the bolt  82  is retracted back out of the bolt hole  84 , allowing the drawer  40  to be opened. 
     The button  86  may signal to the operator whether the crushing mechanism is enabled or not. For example, a red light may be illuminated around the button  86  to indicate that the pill-crushing machine is not ready, either because there is no upper cup present or because the drawer is not fully inserted into the machine. When the machine is ready, i.e. the upper cup is present and the drawer is fully closed, a blue light is illuminated around the button  86  instead of the red light. Other signaling techniques are also possible. 
     Referring to  FIG. 5 , a drawer  40  is shown with a front wall  90  that closes the crushing chamber  44  when the drawer is fully inserted into the pill-crushing machine  32 . Visible in this view is the cup holder  12 , lower cup  14 , upper cup  18 , runner  42 , optional magnet  72  and optional bolt hole  84 . 
     F. Method 
     Referring to  FIG. 6 , a method is shown for preventing operation of a pill-crushing mechanism until an upper cup is in position. In step  200 , the pill-crushing machine is switched on, which results in the laser  20  being switched on, in step  202 . As a result of the laser  20  being switched on, the sensor detects the laser in step  204 , and in step  206  sends a signal to the control module  30 . In step  208 , the control module  30  prevents the starting of the pill-crushing mechanism, even if a start button  86  is pressed and even if there is a lower cup  14  in the drawer  40 . 
     In step  210 , an operator of the pill-crushing machine places one or more pills  16  into a lower cup  14  and places an upper cup  18  over the pills, and then places both cups with the pills therebetween into the drawer  40 . The operator then, in step  212 , fully inserts the drawer  40  loaded with the lower cup  14 , pills  16  and upper cup  18  into the pill-crushing machine  32 . In step  214 , the upper cup  18  in the inserted drawer  40  blocks the laser beam  21 , which is sensed by sensor  22  in step  216  as an intensity drop of the light detected. In step  218 , the sensor  22  sends a corresponding signal to the control module  30 , which, in step  220  enables the starting of the pill-crushing mechanism. In step  222 , an operator of the pill-crushing machine presses a start button, which causes the control module  30 , in step  224 , to activate the drive shaft  54  and pressure plate  56  of the pill-crushing mechanism to crush the pills  16 . 
       FIG. 7  shows optional steps related to the magnet  72  and reed switch  76 . In step  212 , the drawer  40 , loaded with two cups  14 , 18  and one or more pills  16  therebetween, is fully inserted into the pill-crushing machine  32 , as above. Also as above, in step  214  the laser is blocked by the upper cup  18 , in step  216  the sensor  22  detects a drop in laser intensity incident upon it, and in step  218  the sensor sends a signal to the control module  30 . In parallel with steps  214 - 218 , the reed switch  76  senses the magnet  72 , in step  230 , as a result of the drawer  40  being fully closed. In step  232 , as a result of the reed switch operating, a signal is sent to the control module  30 . In step  234 , the control module  30  determines whether both the signals generated in steps  218  and  232  have been, or are being, received. If both of the signals are not received, then the control module  30  waits in step  236  before returning to step  234  to determine whether both signals are received. If both signals are received in step  234 , the control module  30  enables the operation of the pill-crushing mechanism in step  238 . The mechanism can then be started under the command of an operator to crush the pills  16   
       FIG. 8  shows further optional steps for locking the drawer  40  while the pill-crushing mechanism is operating. In step  222 , the start button  86  is pressed by the operator of the pill-crushing machine. In step  250 , the solenoid  80  is activated, which results in the bolt  82  locking the drawer  40  in step  252 . In step  254 , the pill-crushing mechanism operates to crush the pills  16  while the drawer  40  is locked. In step  256 , the mechanism stops as the pill crushing has finished. After the mechanism has stopped, the solenoid  80  is deactivated in step  258 . This causes the bolt  82  to be retracted from the bolt hole  84  in the drawer  40  in order to unlock it in step  260 . The drawer  40  can then be opened to access the powdered medication. 
     G. Further Variations 
     While a straight light path has been shown between the laser  20  and sensor  22 , other, complex paths may be employed, such as paths using mirrors to create folded light paths. Multiple light paths may also be employed. 
     The laser  20  and sensor  22  may be arranged that the laser light intensity that is detected is low when there is no upper cup  18  present and high when the upper cup is present. This may be achieved, for example, by positioning the laser  20  so that its beam reflects off the wall of the upper cup  18  onto the sensor, or off the top surface of the lip  28  of the upper cup and onto the sensor. 
     The sensor  22  may be located at a level below the lip  24  of the lower cup  14  and directed so that it detects light coming down diagonally from a laser that is positioned accordingly. In this configuration, the beam  21  would be blocked by the lip  28  of the upper cup  18  when present, but not when it is absent. 
     The signal from the sensor that indicates the presence of the upper cup may not be present during the whole of the crushing process, because, as the process progresses, the upper cup gradually settles lower down into the lower cup, which may unblock the laser beam. The controller is therefore configured to continue crushing the pills even if the sensor would indicate an absence of the upper cup, provided that the upper cup&#39;s presence was detected immediately prior to the initiation of the crushing operation. 
     The laser may be replaced with another light source, such as a non-laser light emitting diode (LED). The light source may optionally be focused. 
     The pressure plate  56  may have a different form to that shown, and may mechanically engage with the upper cup  18 , for example around a polygonal rim. In other pill-crushing machines, the lower cup  14  may be rotated while the upper cup  18  is held stationary. 
     Mechanical features of the drawer, cup holder and cups may be varied from those shown without departing from the scope of the invention. Mechanical features, shapes and positions are understood to be defined to be within allowable engineering and operating tolerances. For example, where the drawer  40  is described to be fully closed, it is to be understood that it is sufficiently closed for it&#39;s purpose, i.e. to allow the safe operation of the pill-crushing machine, even though there may possibly still be travel available to push the door in further. 
     Sending a signal can be interpreted to be either the actual creation of a signal that is transmitted from a sensor or the ceasing of a signal that is being created by and transmitted from the sensor. Either way, any change in output of the sensor can be interpreted as a signal. A null signal may also be considered to be a signal. The signal may, for example, be a change in voltage, resistance or current. 
     The invention may be implemented using discrete electronic components and/or one or more processors. 
     Any type of sensor may be used in embodiments of the invention, so long as the sensor can detect or distinguish between the presence and absence of the upper cup. For example, sensors operating in a different wavelength range may be used. Sensors working on different principles may be used. Other types of sensor systems may also be used which employ different kinds of sources, provided that these systems can detect the presence and absence of the upper cup. 
     It is conceivable that a mechanical device may be used to detect the presence of the upper cup  18  instead of a source of electromagnetic radiation and corresponding sensor. A mechanical sensor may move from a first position or state when the upper cup  18  is absent to a second position or state when the upper cup is present. The mechanical sensor may operate a microswitch, for example, which signals the presence and absence of the upper cup  18  to the control module  30 . 
     In general, unless otherwise indicated, singular elements may be in the plural and vice versa with no loss of generality. 
     Throughout the description, specific details have been set forth in order to provide a more thorough understanding of the invention. However, the invention may be practiced without these particulars. In other instances, well known elements have not been shown or described in detail to avoid unnecessarily obscuring the invention. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive, sense. 
     The detailed description has been presented partly in terms of methods or processes, symbolic representations of operations, functionalities and features of the invention. These method descriptions and representations are the means used by those skilled in the art to most effectively convey the substance of their work to others skilled in the art. 
     It will be clear to one having skill in the art that further variations to the specific details disclosed herein can be made, resulting in other embodiments that are within the scope of the invention disclosed. Steps in the flowcharts may be performed in a different order, other steps may be added, or one or more may be removed without altering the main functions of the system. Steps shown to occur in parallel may be changed to occur sequentially and vice versa. Flowcharts from different figures may be combined in different ways. All parameters, dimensions, materials, and configurations described herein are examples only and actual values of such depend on the specific embodiment. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.