Patent Publication Number: US-10312623-B2

Title: Spring-loaded contacts

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/503,307, filed Sep. 30, 2014, which is a continuation of U.S. patent application Ser. No. 13/492,905, filed Jun. 10, 2012, which is a continuation-in-part of U.S. patent application Ser. No. 13/272,200, filed Oct. 12, 2011, which are incorporated by reference. 
    
    
     BACKGROUND 
     The number and types of electronic devices available to consumers have increased tremendously the past few years, and this increase shows no signs of abating. Devices such as portable computing devices, tablet, desktop, and all-in-one computers, cell, smart, and media phones, storage devices, portable media players, navigation systems, monitors and other devices have become ubiquitous. 
     These devices often receive power and share data using various cables. These cables may have connector inserts, or plugs, on each end. The connector inserts may plug into connector receptacles on electronic devices, thereby forming one or more conductive paths for signals and power. 
     These inserts or plugs may have contacts that mate with corresponding contacts in a receptacle. These mated contacts may form portions of electrical paths for data, power, or other types of signals. Various types of contacts may be used. One type of contact, a spring-loaded contact, may be used in either a connector insert or a connector receptacle. 
     Spring-loaded contacts may include a plunger biased by a spring, such that the plunger may be depressed when contacting a second contact, then retracted when disengaged from the second connector. But this arrangement may lead to a reduced reliability for the spring-loaded contact. For example, the spring and plunger may become entangled. That is, the spring may become caught between a plunger and a barrel or housing of the spring-loaded contact. This may prevent the plunger from retracting, thus keeping the plunger depressed. 
     Also, when a plunger makes contact with a second contact and is depressed, the plunger may break contact with the barrel or housing. This may lead to large current flow through the spring, which may in turn damage or destroy the spring. 
     Thus, what is needed are spring-loaded contacts that provide an improved reliability by having a reduced tendency for entanglement between a spring and a plunger, and a reduced chance of large currents flowing through the spring. 
     SUMMARY 
     Accordingly, embodiments of the present invention may provide spring-loaded contacts having an improved reliability. An illustrative embodiment of the present invention may provide spring-loaded contacts having a reduced likelihood of entanglement between a spring and a plunger. Another illustrative embodiment may have a reduced likelihood of spring damage caused by excess current flow. 
     Again, in conventional spring-loaded contacts, on occasion a spring or other compliance mechanism may become entangled with a plunger. Specifically, the spring may become caught between the plunger and a housing or barrel of the spring-loaded contact. This may lead to the plunger not retracting or emerging from a face of a connector when the connector is disconnected. Instead, the plunger may remain depressed inside the connector. This may result in either, or both, a cosmetic or functional failure. 
     Accordingly, an illustrative embodiment of the present invention may provide a spring-loaded contact having an isolation object placed between a plunger and a spring. In a specific example, a piston may be placed between a plunger and a spring. The piston may have a first head portion that is wider than the diameter of the spring, and the head portion may be located between the spring and the plunger. This may isolate the spring and the plunger such that the spring does not become entangled with the plunger. For example, the head portion may help prevent the spring from becoming caught between the plunger and a barrel of the spring-loaded contact. The piston may have a second body portion that is narrower and located in the spring. This may help keep the piston in position such that the head portion remains between the plunger and the spring during use. This piston may be made of various conductive materials, such as stainless steel, brass, gold-plated brass, or other material. In other embodiments, the piston may be formed using nonconductive materials, such as ceramics, plastics, or other materials. 
     In other embodiments of the present invention, other isolation objects, such as one or more spheres, cylinders, or other objects having other shapes, may be used. These objects may be conductive, and formed of stainless steel, brass, gold-plated brass, or other material. In other embodiments, they may be nonconductive, and formed using ceramics, plastics, or other materials. The plunger and barrel may be brass or other copper based material, such as bronze. The plunger and barrel may further be plated, for example with gold. 
     Again, in conventional spring-loaded contacts, the plunger may be depressed in a manner that the plunger loses contact with the barrel of the spring-loaded contact. This may result in power supply or other large currents flowing through a relatively narrow spring. The result may be that the spring overheats and breaks or is otherwise damaged. 
     Accordingly, an illustrative embodiment of the present invention may provide an asymmetric interface between a plunger and an isolation object. For example, an embodiment of the present invention may provide a spring-loaded contact having a plunger with an asymmetric back, for example, an eccentrically-tapered back. For example, the back may be eccentrically-conically shaped. This eccentrically-tapered back may contact the head portion of the piston. The eccentricity may help to ensure that the plunger tilts at an angle such that the plunger or the piston, or both, make contact with the barrel, thereby avoiding potential damage to the spring. The spring itself may be formed conductive or nonconductive material, including stainless steel, such as stainless steel 304, or other appropriate material. For example, music wire or high-tensile steel may be used. The spring may be plated with gold, silver, or other material. The spring may also be coated with a dielectric, such as parylene, to further prevent current flow through the spring. In other embodiments of the present invention, a surface of an isolation object may be asymmetric. 
     In another illustrative embodiment of the present invention, an additional object may be placed between a plunger and isolation object. This additional object may be conductive and may provide an electrically conductive path between the plunger and a barrel, though the additional object may instead be nonconductive. 
     In a specific embodiment of the present invention, the additional object may have a spherical or ball shape. The ball may reside between a plunger and an isolation object. The ball may be conductive or nonconductive. A conductive ball may form an electrical path between the plunger and the barrel. In a specific embodiment of the present invention, two additional objects may be employed. These additional objects may both have a spherical shape, and they may both reside between a plunger and an isolation object. Either or both of these additional objects may be conductive or nonconductive. 
     In various embodiments of the present invention, the additional object may be employed with various isolation objects. For example, the isolation object may be a plunger as described above. In other embodiments, the isolation object may be a second ball, that is, it may have a sphere shape. In various embodiments of the present invention, the additional object and the isolation object may be of similar or different sizes. The isolation object may be conductive or nonconductive. 
     Various embodiments of the present invention may also employ various structures, coatings, or other techniques, either alone or in combination, to improve the reliability of spring-loaded contacts. For example, contaminants, such as liquids, may be drawn inside a housing a spring-loaded contact. This liquid may be drawn into the housing by vacuum and suction forces created when the plunger is depressed and released. Accordingly, an embodiment of the present invention may reduce these forces by adding a vent or other opening in the spring-loaded contact housing. By reducing the vacuum and suction forces created when the plunger is depressed and released, liquids and other contaminants are not drawn, or are drawn to a lesser extent, into the housing, and long-term reliability may be improved. The vent may be formed using drilling, laser etching, or other appropriate technique. Also, in various embodiments of the present invention, some or all of the housing, plunger, spring, isolation object, additional object, and other components, may be coated with one or more layers to provide protection against such contaminants, even when they are reduced through the use of a vent. Hydrophobic or oleophobic layers may be used to protect against contaminants. For example, parylene or other coatings may be used. 
     Various embodiments of the present invention may incorporate one or more of these and the other features described herein. A better understanding of the nature and advantages of the present invention may be gained by reference to the following detailed description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a magnetic connector system according to an embodiment of the present invention; 
         FIG. 2  illustrates a connector insert according to an embodiment of the present invention; 
         FIG. 3  illustrates a spring-loaded contact according to an embodiment of the present invention; 
         FIG. 4  illustrates the spring-loaded contact of  FIG. 3  where a plunger has been depressed; 
         FIG. 5  illustrates a cutaway view of a spring-loaded contact according to an embodiment of the present invention; 
         FIG. 6  illustrates a portion of a spring-loaded contact according to an embodiment of the present invention; 
         FIG. 7  illustrates an oblique view of a spring-loaded contact according to an embodiment of the present invention; 
         FIG. 8  illustrates another spring-loaded contact according to an embodiment of the present invention; 
         FIG. 9  illustrates another spring-loaded contact according to an embodiment of the present invention; 
         FIGS. 10A-10C  illustrate spring-loaded contacts according to embodiments of the present invention; 
         FIG. 11  illustrates a spring-loaded contact according to embodiments of the present invention; 
         FIGS. 12A-12C  illustrate contamination of a housing of a spring-loaded contact; and 
         FIG. 13  illustrates a spring-loaded contact having a vented housing to reduce contamination. 
     
    
    
     DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
       FIG. 1  illustrates an electronic system that may be improved by the incorporation of embodiments of the present invention. This figure, as with the other included figures, is shown for illustrative purposes and does not limit either the possible embodiments of the present invention or the claims. 
     This figure includes electronic device  110 . In this specific example, electronic device  110  may be a laptop computer. In other embodiments of the present invention, electronic device  110  may be a netbook or tablet computer, cell, media, or smart phone, global positioning device, media player, or other such device. 
     Electronic device  110  may include a battery. The battery may provide power to electronic circuits in electronic device  110 . This battery may be charged using power adapter  120 . Specifically, power adapter  120  may receive power from an external source, such as a wall outlet or car charger. Power adapter  120  may convert received external power, which may be AC or DC power, to DC power, and it may provide the converted DC power over cable  130  to plug  132 . In other embodiments of the present invention, plug, or insert  132  may be coupled through cable  130  to another type of device. Plug  132  may be arranged to mate with receptacle  112  on electronic device  110 . Power may be received at receptacle  112  from plug  132  and provided to the battery and electronic circuitry in electronic device  110 . In other embodiments of the present invention, data or other types of signals may also be provided to electronic device  110  via plug or insert  132 . 
       FIG. 2  illustrates a connector insert  132  according to an embodiment of the present invention. Connector insert  132  may include an attraction plate  210 , shield or cover  220 , cable  230 , and strain relief  240 . Attraction plate  210  may include front surface  212 . Front surface  212  may include opening  260  for contacts  250 ,  252 ,  254 ,  256 , and  258 . In a specific embodiment of the present invention, contacts  250  and  258  may convey ground, contacts  252  and  256  may convey power, while contact  254  may be used to detect that a connection has been formed. In this specific example, contacts  250  and  258  protrude in front of the other contacts, such that ground paths are formed before power is applied when connector insert  132  is mated with a corresponding connector receptacle. 
     In various embodiments of the present invention, contacts  250 ,  252 ,  254 ,  256 , and  258  may be spring-loaded contacts. Examples of spring-loaded contacts according to embodiments of the present invention are shown in the following figures. 
       FIG. 3  illustrates a spring-loaded contact according to an embodiment of the present invention. Spring-loaded contact  300  may be used as contacts  250 ,  252 ,  254 ,  256 , or  258 , in  FIG. 2 . Spring-loaded contact  300  may be housed in a housing or barrel  310 . Barrel  310  may include tail  312 . Tail  312  may be soldered to a printed circuit board or other structure in a connector, such as connector insert  132  in  FIG. 2 . 
     Spring-loaded contact  300  may further include plunger  320 . Plunger  320  may have tip  322  to mate with a second contact in another connector. Plunger  320  may further include notch or wider portion  324 . Notch  324  may contact portion  314  of housing  310 , thereby limiting the retraction of plunger  320 . 
     Spring-loaded contact  300  may further include a compliance mechanism, such as spring  330 . Spring  330  may extend to retract plunger  320  from barrel  310  when a connector that houses spring-loaded contact  300  is disengaged from a corresponding connector. Spring  330  may compress, thereby allowing plunger  320  to be depressed into housing or barrel  310  when the connector that houses spring-loaded contact  300  is engaged with the corresponding connector. 
     Again, in conventional spring-loaded contacts, a spring may become entangled with a plunger during use. For example, a spring may become caught between a plunger and a barrel or housing. This may prevent the plunger from retracting fully from the housing. This, in turn, may lead to either or both cosmetic and functional failures. 
     Accordingly, embodiments of the present invention may employ an isolation object between plunger  320  and spring  330 . In this specific example, the isolation object comprises piston  340 . Piston  340  may include a head  342  and a body  344 . Head  342  may be wider than a diameter of spring  330 . Head  342  may be located between plunger  320  and spring  330 . Body  344  may be narrower than an inside diameter of spring  330 , it and may be substantially inside spring  330 . 
     While the isolation object is shown here as piston  340 , in other embodiments of the present invention, other isolations object may be used. For example, a sphere may be used as an isolation object. In still other embodiments of the present invention, other isolation objects may be used. For example, a cylinder-shaped, or other shaped object may be used. These isolation objects may prevent spring  330  from getting caught between barrel  310  and plunger  320 . 
     Again, as a plunger is depressed, it may lose contact with a barrel or housing of the spring-loaded contact. Under these circumstances, current may flow through the spring. While this condition may be reasonable when the spring-loaded contact is conveying a signal, it may be damaging when a power supply or ground return is conveyed. This current flow may damage or destroy the spring. Specifically, resistance in the spring may lead to its being heated by the current flow. This heating may cause the spring to lose its elasticity. Such damage may again cause cosmetic or functional failures. 
     Accordingly, embodiments of the present invention may provide an asymmetry in an interface between a plunger and an isolation object, such that when the plunger is depressed, the plunger or isolation object, or both, maintain contact with the barrel such that the spring is protected from large currents. In this specific example, piston  340  contacts plunger  320  at a back surface  326 . Back surface  326  may be asymmetric such that when plunger  320  is depressed, plunger  320  or piston  340 , or both, are tilted relative to a center line through spring-loaded contact  300  and maintain contact with barrel  310 . In this specific example, back surface  326  has an eccentrically-tapered hole. For example, back surface  326  may be eccentrically-conically shaped. In other embodiments of the present invention, back surface  326  may have other shapes. In other embodiments the present invention, the asymmetry may be located on a leading surface of piston  340  or other isolation object. 
     The asymmetry at this interface may force either or both the plunger and the piston into a side of the barrel. This force may help to reduce the low-level contact resistance of spring-loaded contact  300 . An example is shown in the following figure. 
       FIG. 4  illustrates the spring-loaded contact of  FIG. 4  where a plunger has been depressed. Specifically, plunger  420  is shown as being depressed relative to housing  410 . In this figure, spring  430  is compressed and piston  440  is pushed further back into housing  410 . The asymmetric surface  426  of plunger  420  acts to tilt plunger  420  and piston  440 . Specifically, point  428  of plunger  420  may contact housing or barrel  410  at point  418 . Similarly, point  425  of plunger  420  may contact housing or barrel  410  at point  415 . 
     In this example, piston  440  may tilt such that it contacts both back surface  426  of plunger  420  and housing or barrel  410 . Specifically, point  447  of piston  440  may contact plunger  420  and point  427 . Also, point  449  of piston  440  may contact barrel  410  at point  419 . 
     This may provide several electrical paths from tip  422  of plunger  420  to tail  412  of housing  410 . Specifically, current may flow from tip  422  to point  428  of plunger  420  to point  418  of housing  410 , then to tail  412 . Current may also flow from tip  422  to point  425  on plunger  420 , then to point  415  on barrel  410 , then to tail  412 . Current may also flow from tip  422  to point  427  on plunger  420  to point  447  on piston  440 , then to point  449  on piston  440  to point  419  on barrel  410 , then to tail  412 . Depending on the exact geometries and relative position of these components, some or all of these or other electrical paths may be formed as plunger  420  is depressed relative to barrel  410 . 
       FIG. 5  illustrates a cutaway view of a spring-loaded contact according to an embodiment of the present invention. Spring-loaded contact  500  may be the same as spring-loaded contact  300 , or it may be a different spring-loaded contact. Spring-loaded contact  500  includes barrel or housing  510 . Plunger  520  may be at least partially enclosed in housing  510 . Plunger  520  may have notch  524 , which may be used as a stop to limit the retraction of plunger  520 . Plunger  520  may have an asymmetric back  526 . Again, in this example, isolation object  540  is shown as a piston having a head portion  542  and a body portion  544 . Head portion  542  may be wider than a diameter of spring  530 . Body portion  544  may be narrower than inside diameter of spring  530 , and it may be substantially surrounded by spring  530 . Spring  530  may compress and expand, allowing movement of plunger  520 . As before, plunger  520  may electrically contact barrel or housing  510 . 
     In this example, a back surface  526  of plunger  520  is asymmetric. However, even with this asymmetry, a longitudinal length of plunger  520  is approximately the same along all parts of its surface. For example, length L 1  may be approximately the same as length L 2  for each L 1  and L 2 . This is because back surface  526  of plunger  520  may have an outer rim that is at least substantially orthogonal to the longitudinal axis LA of plunger  520 . The result is when plunger  520  is depressed in barrel  510 , when the tip of plunger  520  is moved in various directions, plunger  520  may tilt approximately the same amount in each direction. This may assist the spring-loaded contacts to make connections with fixed contacts in a second connector. 
     Again, while in this example, a back  526  of plunger  520  is shown as having an asymmetric surface, in other embodiments of the present invention, a leading edge of piston  540  or other isolation object may have an asymmetric surface. 
       FIG. 6  illustrates a portion of a spring-loaded contact according to an embodiment of the present invention. Portion  600  may be a portion of spring-loaded contacts  300  or  500 , or other spring-loaded contact according to embodiments of the present invention. This figure includes plunger  620 , which has notch  624 , piston  640 , comprising a head  642  and body  644 , and spring  630 . 
       FIG. 7  illustrates an oblique view of a spring-loaded contact according to an embodiment of the present invention. The spring-loaded contact  700  may be the same as the other spring-loaded contacts shown herein, or it may be a different spring-loaded contact. Spring-loaded contact  700  may include a housing or barrel  710 , plunger  720 , spring  730 , and isolation object  740 . Housing  710  may include tail  712  to connect to a printed circuit board or other structure in a connector, such as connector insert  132  in  FIG. 2 . Isolation object  740  is shown as a piston having a head  742  and body  744 . 
     Again, in other embodiments of the present invention, other isolation objects may be used. One example is shown in the following figure. 
       FIG. 8  illustrates another spring-loaded contact according to an embodiment of the present invention. In this example, a dome shaped cap  840  is used as an isolation object. Specifically, cap  840  is placed over spring  830 . In this way, cap  840  isolates spring  830  from plunger  820 . 
     In various embodiments of the present invention, the components of these and other spring-loaded contacts may vary. For example, the plunger and barrel may be brass or other copper based material, such as bronze. The plunger and barrel may further be plated, for example with gold. The spring may be formed of stainless steel, such as stainless steel  340 . Spring  330  may be further coated with a dielectric material. In a specific embodiment of the present invention, the dielectric may be parylene. The piston may be made of various conductive materials, such as stainless steel, brass, gold-plated brass, or other material. The piston may be formed using nonconductive materials, such as ceramics, plastics, or other materials. 
     In these various examples, a front edge of an isolation object may be dome-shaped. In some examples, the dome shape may be somewhat spherical. In other embodiments of the present invention, the front edge of the isolation object may be flatter than a spherical shape. This may shorten the length of the isolation object, and therefore the length of the spring-loaded contact. 
     In various embodiments of the present invention, an additional object may be placed between a plunger and an isolation object. This additional object may be conductive and may provide an electrical path between the plunger and a barrel, though the additional object may instead be nonconductive. In still other embodiments the present invention, two additional objects may be employed. An example is shown in the following figure. 
       FIG. 9  illustrates another spring-loaded contact according to an embodiment of the present invention. This spring-loaded contact includes barrel  910 , plunger  920 , spring  930 , and piston  940 . Piston  940  may include a head portion  942  and a tail portion  944  that is substantially surrounded by spring  930 . 
     In this example, two additional objects  960  and  970  are located between plunger  920  and piston  940 . Additional objects  960  and  970  are shown as spheres, though in other embodiments of the present invention these may have other shapes. In a specific embodiment of the present invention, spheres or additional objects  960  and  970  may be conductive, though in other embodiments of the present invention, either or both additional objects  970  and  970  may be nonconductive. 
     Either or both of back surface of plunger  926  and front surface of piston head  942  may be convex as shown. This convex shape may push additional objects or spheres  960  and  970  against barrel  910  when plunger  920  is depressed. This may provide good contact between plunger  920  and barrel  910 . Specifically, electrical paths between plunger  920  through spheres or additional objects  960  and  970  to barrel  910  may be formed. In this example, piston  940  may be insulative, though in other embodiments of the present invention, it may be conductive. If piston  940  is nonconductive, spring  930  may be isolated from large currents during operation. 
     In other embodiments of the present invention, pistons  940  may be replaced by isolation objects having other shapes. For example, such a replacement isolation object may be spherical or ball shaped. As in the above example, one or more additional objects may be placed between a plunger and isolation object. Also as in the above examples, a back of a plunger may have asymmetrical shapes. Examples are shown in the following figures. 
       FIGS. 10A-10C  illustrate spring-loaded contacts according to embodiments of the present invention. In  FIGS. 1010A and 10B , a piston may be replaced with spring insulators  1070 A and  1070 B. Specifically,  FIG. 10A  illustrates a spring-loaded contact having a spherical isolation object (or spring insulator)  1070 A and a spherical additional object  1060 A. In this example, spring insulator or isolation object  1070 A may be nonconductive, though in other embodiments of the present invention, spring insulator or isolation object  1070 A may be conductive. In this example, the additional object may be conductive ball  1060 A. Conductive ball  1060 A may form a current path between plunger  1020  and barrel  1010 . 
     In  FIG. 10B , conductive ball  1060 B is shown as being larger than conductive ball  1060 A. The smaller conductive ball  1060 A may reduce an overall length of a spring-loaded contact. 
     In  FIG. 10C , plunger  1070 C may be used in place of spring insulators  1070 A and  1070 B. Again, plunger  1070 C may have a reduced height, thereby allowing a resulting spring-loaded contact to be shorter. 
       FIG. 11  illustrates another spring-loaded contact according to an embodiment of the present invention. In  FIG. 11 , a piston may be replaced with spring insulator  1170 . Specifically,  FIG. 11  illustrates a spring-loaded contact having a spherical isolation object (or spring insulator)  1170 . In this example, spring insulator or isolation object  1170  may be nonconductive, though in other embodiments of the present invention, spring insulator or isolation object  1170  may be conductive. 
     Again, various embodiments of the present invention may also employ structures, coatings, or other techniques, either alone or in combination, to improve the reliability of spring-loaded contacts. For example, contaminants, such as liquids, may be drawn inside a housing a spring-loaded contact. Contaminants may be drawn into the housing by vacuum and suction forces created when the plunger is depressed and released. Accordingly, an embodiment of the present invention may reduce these forces by adding a vent or other opening in the spring-loaded contact housing. By reducing the vacuum and suction forces created when the plunger is depressed and released, liquids and other contaminants are not drawn, or are drawn to a lesser extent, into the housing, and long-term reliability may be improved. Examples of this are shown in the following figures. 
       FIGS. 12A-12C  illustrate the contamination of a spring-loaded contact.  FIG. 12A  illustrates a spring loaded contact having a plunger with a contaminant on its surface. This spring loaded contact includes housing  1210 , plunger  1220 , spring  1230 , and spring-isolation object  1270 . In this example, contaminant  1290  may reside on a portion of a surface of plunger  1220  near an opening of housing  1210 . Contaminant  1290  may include liquid, dust, grit, or other liquid or particulate matter. 
     In  FIG. 12B , plunger  1220  is depressed, thereby drawing contaminant  1290  into housing  1210 . Specifically, contaminant  1290  may be drawn into the spring-loaded contact between housing  1210  and plunger  1220 . While air is forced out of the spring-loaded contact when plunger  1220  is depressed, the relatively larger space between housing  1210  and plunger  1220  near the front of plunger  1220  may provide adequate space for contaminant  1290  to enter housing  1210 . 
     In  FIG. 12D , plunger  1220  is released. This action creates a vacuum or low-pressure effect inside the spring-loaded contact which draws contaminant  1290  further inside housing  1210 . After plunger  1220  is depressed and released multiple times, more of contaminate  1290  may enter the spring-loaded contact chamber, specifically, the open portion of the spring-loaded contact where spring  1230  and isolation object  1270  reside. This contamination may foul or degrade spring  1230  or other associated components, which may lead to reduced functionality or failure. 
     Again, contaminate  1290  may be pulled inside the spring-loaded contact by the low pressure created inside the chamber as plunger  1220  is released. Accordingly, embodiments of the present invention may employ a vent or other opening to prevent this low pressure or vacuum from being created. Since the vacuum or low pressure is not created, contaminate  1290  is not drawn into the chamber of the spring-loaded contact, or at least it is drawn into the chamber to a lesser degree. An example is shown in the following figure. 
       FIG. 13  illustrates a spring-loaded contact having a vented housing to reduce contamination. The spring-loaded contact includes housing  1510 , plunger  1320 , spring  1530 , isolation object  1370 , and vent  1380 . As before, contaminate  1390  is located on a surface of plunger  1320  near an opening of housing  1310 . In this example, as plunger  1320  is released, vent  1380  may provide an opening for air to enter the chamber in housing  1510 . Since a vacuum or low pressure is not created in the chamber, contaminate  1390  is not pulled into housing  1310 . Instead, contaminate  1390  may be pushed out of housing  130  by plunger  1320 . This may reduce or prevent the contamination of the chamber of the spring-loaded contact by contaminate  1390 . 
     Again, in other embodiments of the present invention, portions of the spring-loaded contact may be coated. This coating may further protect the spring-loaded contact in the eventuality that some contamination occurs. Specifically, in various embodiments of the present invention, some or all of housing  1310 , plunger  1320 , spring  1330 , isolation object  1370 , additional object (not shown in this example), and other components, may be coated with one or more layers to provide protection against such contaminants, even when the risk of contamination may be reduced through the use of a vent or other opening. In various embodiments of the present invention, hydrophobic or oleophobic layers may be used to protect against contaminants. For example, parylene or other coatings may be used. 
     In various embodiments of the present invention, vent  1380  may be formed in various ways. For example, vent  1380  may be formed using drilling, laser etching, or other appropriate technique. In various embodiments of the present invention, the vent may be made of a comparable or larger size as compared to a gap between housing  1310  and plunger  1320 . This may help prevent a low-enough chamber pressure from occurring that would draw in contaminants. In a specific embodiment of the present invention, a gap between housing  1310  and plunger  1320  may be 0.02 mm. Given the resulting area of this gap around plunger  1320 , a vent  1380  may be made to be 0.4 mm in diameter. 
     The above description of embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form described, and many modifications and variations are possible in light of the teaching above. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Thus, it will be appreciated that the invention is intended to cover all modifications and equivalents within the scope of the following claims.