Abstract:
A membrane switch that uses a magnetic force for assisting in the actuation process. A magnet positioned adjacent to the membrane switch causes a magnetic attraction or repulsion that remotely transfers a limited but sufficient force for closing the membrane switch. The invention includes a magnet, a membrane switch, and an actuator. In an attraction actuation embodiment, the actuator is constructed of a magnetically-affected material that is attracted to the magnet to thereby close the membrane switch. In a repulsion actuation embodiment, the actuator is constructed of a magnetic material with the poles of the magnet and actuator inversely aligned such that they repel each other. In both embodiments, the actuating force applied to the magnet or actuator is not directly passed to the membrane switch.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention is directed to a method of actuating a membrane switch and, more particularly, to a method of positioning a membrane switch relative to a magnetic material and magnet to use the magnetic force therebetween to actuate the switch.  
         BACKGROUND OF THE INVENTION  
         [0002]    Membrane switches are used in a variety of applications, including but not limited to selection of the grade of fuel and/or interaction with payment devices in a fuel dispensing environment. Membrane switches typically have a flexible plastic membrane layer separated from a substrate by a nonconductive spacer. Openings in the spacer permit a user to push the membrane through the spacer, bringing facing electrical contacts on the internal surfaces of the membrane and substrate into contact with one another thereby closing the switch. The natural resilience of the membrane returns it to its spaced position upon removal of the actuating force.  
           [0003]    Membrane switches are relatively easily damaged by rough treatment. Additionally, outdoor environments may causes the switches to degrade and become ineffective. The electrical contacts are often very fragile and continual actuation and deactuation often result in damage and failure of the switch. Additionally, the actuating force causing contact of the membrane layers is directly applied to the layers thereby increasing the likelihood of damage to the switch.  
           [0004]    A similar concern is that the membrane switch continually work in a reliable manner. A switch, such as that previously described on a fuel dispenser, may be actuated hundreds of times each day. The switch should be able to undergo this amount of usage and still operate properly. If the switch becomes worn or if an adequate actuating force is not applied to the membrane layers, a user may have to repeatedly actuate the switch to close the contacts and begin service. This is frustrating to the user, and may result in loss of sales if the worn switch is not repaired. Additionally, service calls may have to be performed to fix a broken membrane switch, which may be costly. Thus, the switch should be easy for a user to actuate, yet somehow restrict the amount of force directly applied to the layers so as not to cause premature wear.  
         SUMMARY OF THE INVENTION  
         [0005]    The invention is directed to a membrane switch that uses a magnetic force for assisting in the actuation process. A magnet positioned adjacent to the membrane switch causes a magnetic attraction or repulsion that remotely transfers a limited but sufficient force for closing the membrane switch. The invention includes a magnet, a membrane switch, and an actuator constructed of a magnetically-affected material.  
           [0006]    In an attraction actuation embodiment, the membrane switch is positioned between the magnet and a magnetically-attracted actuator. The magnet is pressed within proximity of the actuator. The magnetic force of the magnet pulls the actuator against the membrane switch thereby activating the membrane switch.  
           [0007]    The repulsion actuation embodiment includes a magnetic actuator positioned between the membrane switch and the magnet. The magnet and actuator are aligned such that their poles are inversely positioned (south to south or north to north). As the magnet is moved within close proximity to the actuator, magnetic force pushes the actuator away from the magnet and against the membrane switch.  
           [0008]    In both embodiments, the physical actuating force applied by the user is not directly transferred to the membrane switch as the magnet and switch do not touch. Rather, a magnetic attraction or repulsion remotely transfers a limited but sufficient pressure to close the membrane switch. This type of switch actuation is reliable, and does not cause undue wear on the membrane switch. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a perspective view of one embodiment of at least one membrane switch of the present invention within a fuel dispenser;  
         [0010]    [0010]FIG. 2 is an exploded partial perspective view illustrating one embodiment of an attraction actuation embodiment of the present invention;  
         [0011]    [0011]FIG. 3 illustrates a partial perspective view of the switch of FIG. 2 in an actuated state;  
         [0012]    [0012]FIG. 4 is a partial perspective view of another embodiment of the attraction actuation embodiment;  
         [0013]    [0013]FIG. 5 is an exploded partial perspective view of one embodiment of a repulsion actuation embodiment of the present invention;  
         [0014]    [0014]FIG. 6 is a partial perspective view illustrating the switch of FIG. 5 in an actuated state; and  
         [0015]    [0015]FIG. 7 is an exploded partial perspective view of another embodiment of the repulsion actuation embodiment.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    [0016]FIG. 1 illustrates a fuel dispenser  100  representative of one use of the membrane switch  10  of the present invention. A number of membrane switches  10  may be positioned across the face of the dispenser  100  for the user to select the grade of fuel dispensed through nozzles and hose assembly  102 . A user presses the surface  104  of the membrane switch  10  to select the grade of fuel. Fuel dispenser  100  comprises an outer housing having an associated display  11 , soft keys  12 , and a keypad  14  to interact with the user for selecting fuel and possibly other goods and services. One embodiment of a fuel dispenser is disclosed in U.S. Pat. No. 6,098,879, herein incorporated by reference in its entirety. FIG. 1 is included for illustrative purposes of one environment in which membrane switch  10  is used. Numerous other environments are also contemplated by the present invention such as cameras, computer keypads, soft keys, appliances such as washing machines, calculators, and scientific and medical equipment.  
         [0017]    [0017]FIG. 2 illustrates one embodiment of a membrane switch  10   a  using an attraction actuation method. Membrane switch  10   a  includes layers  32   a,    32   b,  and  32   c  positioned between magnet  20  and a magnetically-attracted actuator  40 . Magnet  20  is moveably positioned relative to the membrane switch  10   a  and moves between a non-actuated position illustrated in FIG. 2 and an actuated position illustrated in FIG. 3. Magnet first end  24  is positioned a distance Y from membrane switch first layer  32   a  in the deactivated state illustrated in FIG. 2 and a distance X in the activated state illustrated in FIG. 3. Magnet  20  maintains a distance from and never contacts membrane switch  10   a  thereby ensuring that no undue force is exerted on the membrane switch  10   a  which could cause damage and/or premature wear.  
         [0018]    Membrane switch  10   a  comprises a first layer  32   a  and a second layer  32   b.  A spacer layer  32   c  may also be positioned within the switch  10   a.  The opposing sides of each layer (illustrated as the bottom side of first layer  32   a  and the top side of second layer  32   b  in FIG. 2) include electrical contacts. The switch  10   a  is open when the layers  32   a,    32   b  are separated and closed when the layers  32   a,    32   b  contact. In one embodiment, the membrane layers  32   a,    32   b  are composed of a flexible plastic or polyester sheet with conductive ink containing silver or carbon is screened thereon. Other examples of a membrane switch include U.S. Pat. No. 5,921,382 entitled “Magnetically Enhanced Membrane Switch”, and U.S. Pat. No. 6,069,552 entitled “Directionally Sensitive Switch”, both of which are incorporated here in their entirety.  
         [0019]    One of the membrane layers  32   a,    32   b  is further equipped with a contact line  34  that extends to a controller unit  200  for powering the equipment actuated by the switch  10   a.  In the fuel dispenser embodiment of FIG. 1, controller  200  controls the function of the fuel dispenser  100  including accepting payment, activating a fuel pump, activating a vapor recovery pump, etc. Alternatively, contact line  34  may extend directly to the unit being actuated and bypass a controller arrangement.  
         [0020]    An actuator  40  is positioned adjacent the second layer  32   b  and on the opposite side of the switch  10   a  from the magnet  20 . In the attraction actuation method, actuator  40  is constructed of a magnetically-attracted material that is magnetically drawn to the magnet  20  when placed within a predetermined range. The predetermined range is sized such that actuator  40  is weakly attracted when magnet  20  is placed a distance Y from the first layer  32   a,  and is strongly attracted when magnet  20  is placed a distance X from the first layer  32   a.  In one embodiment, actuator  40  is constructed of iron or steel. The magnetic range may vary depending upon the power of the magnet  20 , and size and composition of the actuator  40 . Actuator  40  may have a variety of shapes, dimensions, and sizes.  
         [0021]    Membrane switch second layer  32   b  may include a cavity  42  for housing the actuator  40 . Additionally, a backing plate  44  may be positioned along the second layer  32   b  for containing the actuator  40 . Actuator  40  is attached to second layer  32   b  such that the magnet attraction results in the second layer  32   b  moving with the actuator  40 . Actuator  40  may be fixed in place via adhesive, mechanical fasteners, or positioned within cavity  42  and entombed by a backing plate  44  and a face plate (not illustrated). One skilled in the art will understand that a variety of options are available for attaching actuator  40  to second layer  32   b  and are included within the scope of the present invention.  
         [0022]    In the non-actuated state illustrated in FIG. 2, magnet  40  is positioned a distance Y from the first layer  32   a  such that little magnetic attraction occurs with the actuator  40 . In this state, the first and second layers  32   a,    32   b  are separated and the switch  10   a  is not actuated. In the actuated state illustrated in FIG. 3, magnet  20  is moved in the direction of arrow  50  towards the membrane switch  10   a  via an actuating force. In the embodiment illustrated in FIG. 1, the actuating force is supplied by the user pressing the surface  104  of the membrane switch  10   a.  In FIG. 3, the proximity of the magnet  20  to the actuator  40  results in a magnetic force of adequate strength to pull the actuator  40  towards the magnet  20 . This results in the first and second layers  32   a,    32   b  contacting and the membrane switch  10   a  being actuated. It is important to note that the magnet  20  maintains a minimum distance between the magnet first end  24  and first membrane layer  32   a.  This orientation causes the force applied to the membrane switch  10   a  to be limited to that supplied by the magnetic attraction thus preventing undue force that may be applied by the user to be conveyed to the membrane switch  10   a.  Additionally, the strength of the magnet and the distance X is predetermined such that the switch consistently closes when the magnet  20  is moved to the closed state of FIG. 3.  
         [0023]    [0023]FIG. 4 illustrates another embodiment of the attraction actuation method. Membrane switch first and second layers  32   a,    32   b  are positioned between magnet  20  and actuator  40 . In the non-actuated state, magnet  20  is positioned a distance from actuator  40  and first and second layers  32   a,    32   b  are separated. In the actuated state in which magnet  20  is moved closer, actuator  40  is attracted and moves towards magnet  20  thereby forcing the layers  32   a,    32   b  together and closing the membrane switch.  
         [0024]    This embodiment may also feature the actuating force of the user being applied to the actuator  40  which moves the actuator  40  within range of magnet  20 . Once within magnetic range, the closing force is caused by the magnetic attraction between magnet  20  and actuator  40 .  
         [0025]    In one embodiment, the roles of the actuator  40  and magnet  20  may be reversed. The actuator  40  is maintained a minimum distance from the membrane switch  10   a  while the magnet  20  contacts the switch  10   a  causing the layers  32   a  and  32   b  to be forced together thus causing switch  10   a  closure.  
         [0026]    [0026]FIGS. 5 and 6 illustrate one embodiment of repulsion actuation. The actuator  40  is a magnetic material positioned within a cavity  42 . A backing member  44  may again be positioned for containing the actuator  40  in the cavity  42 . Additionally, a face plate (not illustrated) may be positioned between the actuator  40  and membrane switch  10   a  to enclose the actuator  40  within the cavity  42 . As with the previous method, actuator  40  may be held within the cavity  42  in a manner of different formats. The membrane switch first layer  32   a  is positioned distant from the magnet  20  with the second layer  32   b  and actuator  40  positioned therebetween. Additionally, a spacer  32   c  may be positioned between the membrane layers  32   a,    32   b.    
         [0027]    The magnet  20  and magnetic actuator  40  are arranged such that their poles are inversely positioned. This orientation may include magnet south end facing actuator south end, or magnet north end facing actuator north end such that when brought in range, a magnetic repulsion occurs.  
         [0028]    In the non-activated state illustrated in FIG. 5, magnet  20  and actuator  40  are positioned a distance apart such that magnetic force is not strong enough to move the actuator  40 . When an actuating force is applied to the magnet  20  as illustrated by arrow  51  in FIG. 6, the inversely positioned poles of magnet  20  and actuator  40  repel one another resulting in the actuator  40  pushing layer  32   a  to contact layer  32   b  causing the electrical contacts (not illustrated) on layers  32   a  and  32   b  to contact. The repulsion and contacting of the first and second layers  32   a,    32   b  result in the membrane switch  10   a  being actuated. As with the previous embodiment, the repulsion actuation embodiment again maintains a distance Z between the magnet  20  and membrane switch  10   a.    
         [0029]    [0029]FIG. 7 illustrates another embodiment of the repulsion actuation method. Actuator  40  is positioned between magnet  20  and first and second layers  32   a,    32   b.  In the non-actuated state, the distance between the magnet  20  and actuator  40  is sized such that a slight repulsion force is created. When magnet  20  and actuator  40  are moved closer together, repulsion forces cause actuator to move away from magnet  20  thereby forcing first and second layers  32   a,    32   b  together and closing the switch.  
         [0030]    The above described and illustrated embodiments comprise the magnet  20  positioned distant from the membrane switch  10   a.  In alternative embodiments that correspond to those described above, the actuator  40  may be positioned distant from the membrane switch  10   a.  By way of example using the embodiment illustrated in FIG. 2, the roles of the actuator and magnet may be reversed. The magnet may be placed within the membrane switch and the actuator distantly positioned. The reversal of roles between the actuator and magnet may be included in each of the embodiments illustrated and described.  
         [0031]    The present invention may also include a means for causing the magnet  20  to move away from the actuator  40  to reopen the membrane switch  10   a.  In one embodiment, a spring is positioned to bias the magnet  20  away and separate the membrane switch layers  32   a,    32   b.    
         [0032]    The present invention may be carried out in other specific ways than those herein set forth without departing from the scope and essential characteristics of the invention. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.