Abstract:
An interchangeable plug device includes an electrical plug detachably mountable to a casing and movable between a detached and an operative position relative to the casing, and a releasable locking mechanism integral with the electrical plug to maintain the plug in an operative position. The locking mechanism can be released by a user to allow the plug to be moved to the detached position. A preferred form of locking mechanism is a depressible lock bar connected to or integral with an electrical plug body, which is designed to engage a detent in a casing. A preferred form of electrical connection between the plug and any casing comprises a submerged pin and sleeve configuration to protect the user or passerby from electric shock if the plug is detached from its operative position but remains a source of live current. A variety of interchangeable electrical plugs can preferably be fitted to the same casing.

Description:
This application is a continuation-in-part of U.S. patent application Ser. No. 08/414,209, filed Mar. 30, 1995, now U.S. Pat. No. 5,634,806 which is a continuation-in-part of U.S. patent application Ser. No. 08/201,397, filed Feb. 24, 1994 now abandoned. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to plug mechanisms compatible with a variety of electronic devices, and more particularly to interchangeable plug mechanisms which can be detached from electronic devices for convenient transportation or storage and also can be interchanged for use with different sockets used in various parts of the world. 
     BACKGROUND OF THE INVENTION 
     People rely heavily on a wide variety of electrical devices. Almost all of these devices draw power ultimately delivered to the user through a wall outlet or socket. While many electrical devices are sold for use throughout the world, there is no world standard for electrical plug and socket configurations, size, shape, position or number of prongs. The wide variety of socket configurations in use worldwide burdens international suppliers of products to varied countries and international travelers who wish to use electrical devices in varied locations. 
     Differences exist in both supply current and physical socket configuration characteristics. Most industrial nations use a standardized alternating current supply socket with a hot side and a neutral side. Some plugs and sockets specifically incorporate a third earth or ground lead while others do not. There is no world standard for power supply voltage or frequency. Voltage can vary from 100 to 240 volts. Frequency can vary from 50 to 60 cycles per second (hertz). 
     Fortunately, many electronic devices, and essentially all battery powered electrical devices, ultimately run on direct current, so a “universal” power supply that converts 100-240 volts AC at 50-60 hertz into a direct current suitable for a particular application is well known in the art. However, a problem remains with physically accessing an AC current source supplied through any number of socket configurations. 
     Differing plug configurations have posed a problem to manufacturers who sell equivalent products into various parts of the world. The need for plug diversity is also a significant problem for people who travel to different parts of the world and need to take electrical devices with them, such as hair dryers, electronic cameras, phones or computers. 
     The traditional solution for the mechanical configuration problem is to provide adapters including a socket to accommodate the prongs of the desired electrical device integrated with a second set of prongs in a configuration for a local socket. These adapters suffer from some significant problems. The most important is that the adapters are bulky and at a minimum cause the prongs of the original device to be extended by at least the length of the additional set of prongs. Since most plug devices are designed to be secured by spring tension and interaction with a wall plug, this can pose a significant mechanical disadvantage. The increased lever arm created by the additional prong length will tend to shift the plug downward, tending to pry the plug out of the wall socket. This will be true even for a light weight plug. 
     The lever arm problem is accentuated with devices that are larger than a simple plug. Many battery chargers or power supplies are designed to be wall-mounted at a wall socket. A typical device includes a casing which terminates in a plug designed to plug directly into the wall socket. The casing is often designed to lie against a wall to provide mechanical stability and to maintain the plug prongs in proper contact with the wall socket. If an adapter must be used, the unit loses the stability of resting against the wall and, because even a small amount of weight at the end of a lever arm will create a torque which will tend to pry the prongs out of the wall socket, such a plug adapter is generally unusable for such wall-mounted plug-in devices. 
     Angling the plug severely can compromise the electrical connection to the point that the plug no longer is in electrical contact with source current. This type of angling may lead to partial separation from the wall socket and may expose the prongs of the plug in such a way that a person or animal might come into contact with live current, thereby causing bodily harm. 
     A further problem with existing plugs is the awkward shape of the plug with prongs protruding from the end. If, for example, a plug is moved from one location to another, the prongs of the plug extend outward and can be difficult to pack or store or can catch on clothing when packed into a travel case. 
     A few plug devices have been designed with a plug or prongs which fold into a casing. For example, some rechargeable flashlights include the collapsible prongs which can be rotated into a position extending out from the body of the flashlight and plugged directly into a wall socket or extension cord. Some telephone charging stations include a cradle for the telephone and a rotatable plug which can be extended into position for plugging into a wall socket, or collapsed into a space in the shell of the charging station, particularly so that a user may slip a charging station into a pocket, a briefcase, or other container. However, these devices still depend on adapters for use world-wide. 
     Presently available collapsible plug devices suffer from various problems which make them inconvenient or even dangerous to use. In particular, the rotatable plug has only a weak spring holding the plug in position. It does not take much effort to collapse the plug, which may cause the plug to partially or completely pull out of a wall socket. This can compromise the electrical connection to the point that the plug no longer is in electrical contact with source current. In some circumstances, this may expose the prongs of the plug in such a way that a person, might come into contact with live current, thereby causing bodily harm. In addition, a collapsing plug might pinch the user. 
     The present invention overcomes these problems by providing an interchangeable and/or collapsible plug device, which can be securely maintained in a connected position relative to a device casing, and can be easily separated and, if desired, folded to a compact, collapsed position. The collapsible prong feature can be incorporated within an interchangeable plug device which can be designed for use in a variety of plug configurations and still provide the mechanical advantages of fitting closely to the socket and, generally, against a wall. Moreover, the inventive device provides a safe means for deriving current from an interchangeable plug while minimizing the risk of exposure to a live prong or connector. 
     SUMMARY OF THE INVENTION 
     To address the shortcomings of available plug devices, the present invention provides an interchangeable electrical plug detachably mountable to a casing and moveable between a detached and an operative position relative to the casing, the electrical plug comprising a plurality of prongs in electrical communication with an electrical device when mounted to the casing, a releasable locking means to maintain said electrical plug in said operative position, whereby said electrical plug is locked into the operative position until and unless the releasable locking means is released, and an electrical contact recessed with said electrical plug for preventing inadvertent contact therewith when said electrical plug is in said detached position. 
     Accordingly, it is an object of this invention to provide an interchangeable electrical plug device. 
     Another object of this invention is to provide a releasable locking means so that a user can readily release the locking mechanism and move the plug from an operative to a detached position relative to the casing. 
     A further object of this invention is to provide a means for securing and electrically connecting an interchangeable plug device with a compatible carrier in a manner which provides optimal user safety. 
     Still another object of this invention is to provide an interchangeable plug with collapsible prongs which can be maintained in an extended position. 
     Yet another object of this invention is to provide a releasable securing means for the extended prongs so that a user can readily release the securing mechanism and move the prongs from an extended to a collapsed position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The aforementioned advantages of the present invention as well as additional advantages thereof will be more clearly understood hereinafter as a result of a detailed description of a preferred embodiment of the invention when taken in conjunction with the following drawings in which: 
     FIGS. 1A,  1 B,  1 C,  1 D and  1 E illustrate a perspective view of the interchangeable plug device showing several interchangeable plugs positioned to be moved to an operative position; 
     FIGS. 2A,  2 B,  2 C,  2 D, and  2 E illustrate exploded views of the various embodiments of the inventive interchangeable plug; 
     FIG. 3 illustrates a perspective view of the interchangeable plug showing a representative interchangeable plug in an operative position; 
     FIGS. 4A,  4 B and  4 C illustrate a cross-section of the device, showing the plug body and carrier ready to be connected to the device ( 4 A), connected ( 4 B) and released and ready to be detached ( 4 C); 
     FIG. 5 illustrates a cross-section of the device, showing the plug body and carrier ready to be connected to the device; 
     FIG. 6 is an exploded view of a preferred embodiment of the present invention including the collapsible prong feature; 
     FIG. 7 is a side exploded view of the collapsible prong feature of the present invention; 
     FIGS. 8A,  8 B and  8 C illustrate a cross-section of the device showing the plug body and carrier with the prongs in a fully collapsed position ( 8 A), partially extended position ( 8 B), and fully extended position ( 8 C). 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The interchangeable plug of this invention include a plug mountable to a casing, a locking device and a recessed electrical contact for placing the plug and an electrical device in electrical communication with one another. The specific shape of the casing can be modified in many ways to accommodate specific design needs. The plug can also be modified to accommodate specific design needs, including the number and configuration of electrical prongs to adapt to a variety of standard, electrical outlets. The drawings illustrate a representative device but one skilled in the art will recognize that a variety of devices can be designed and manufactured, which are encompassed by the teachings of this invention. 
     Referring to FIGS. 1A,  1 B,  1 C,  1 D and  1 E, casing  1  includes cavity  2  with channels  28  which are designed to accommodate any one of the carriers  13  depicted in the Figures with tongues  14 . Similarly, opening  3  with submerged conducting pins  25  are designed to accommodate conducting sleeves  16 . In the description and claims which follow, carriers  13  and tongues  14  may also be referred to as “plates”. In a preferred embodiment, casing  1  is made of high impact thermoplastic material, with top and bottom halves which can be sealed together with ultrasonic bonding. Carrier  13  shown in FIG. 1 b  has a body  10  which supports a plurality of prongs  11 . Carrier  13  shown in FIG. 1 c  has only two prongs  11 ′ of a different shape from prongs  11  of FIG. 1 b . Similarly, FIG. 1 d  shows a carrier  13  with a body  10 ″ and cylindrical prongs  11 ″ and FIG. 1 e  shows a carrier with a body  10 ′″ with a different style of prongs  11 ′″. 
     As shown in FIGS. 1 b ,  1   c ,  1   d , and  1   e , each of the carriers  13  is “L” shaped or “el” shaped, having a short leg  16  and a long leg  17 . The short leg  16  of each carrier  13  is dimensioned to be snugly received in a first recess  18  in a first planar surface  30  in casing  1  and the long leg  17  of each carrier is dimensioned to be snugly received in a second recess  19  in a second recess  31  in casing  1 . The second recess  31  is generally perpendicular to the first recess  30 . 
     FIGS. 2A,  2 B,  2 C,  2 D, and  2 E provide exploded views of various embodiments of the inventive interchangeable plug. Cover plates  50  are aligned and, preferably, ultrasonically bonded or otherwise fastened together to form carrier  13 . Conductors  65  lead at one end to prongs  11  and at the other end to to conducting sleeves  16 , illustrated in greater detail in FIGS. 4A and 5. This highly modular design allows for greater economies of scale when manufacturing the inventive interchangeable plugs. 
     Referring to FIG. 5, carrier  13  is connected to or integral with prongs  11 . Each conducting sleeve  16  within carrier  13  is electrically connected to one prong  11  and is designed to mate with a corresponding conducting pin  25  positioned in cavity  3 . The conducting pin/sleeve configuration for the electrical contacts of the preferred embodiment increases the safety of the interchangeable plug design by making user contact with a live contact highly unlikely. 
     In one embodiment, shown in FIG. 1A, power supply  7  is connected to conducting pins  25  and also through electrical cable  5  to an electrical connection means such as power adapter plug  6 , which can in turn be connected to an electronic device  8 . 
     FIG. 5 illustrates a cutaway view of a preferred embodiment of the new device. Carrier  13  is a generally rectangular element with a tongue  14  along each of two sides. Detent  15 , shown in greater detail in FIG. 4A, is cut into casing  1 . 
     FIGS. 4A,  4 B and  4 C show lock bar  22  deformably positioned on carrier  13 . Lock bar  22  is made of a suitable material, such as a plastic material, which is resilient, tends to return to a preferred position, and can be secured at one end and be bent repeatedly to perform the needed release function yet return to a resting position with enough tension to perform the needed latch function. Lock bar  22  is preferably formed integral with carrier  13  and more specifically is integral with tongues  14 . Release button  20  is connected to or preferably integral with lock bar  22 . Lock bar  22  includes latch  23  and latch tip  24 , which are designed to engage detent  15  in casing  1 . In an alternative embodiment, the lock bar, detent and latching mechanisms could switch positions relative to the casing and carrier. 
     When carrier  13  and casing  1  are integrated into a singular unit, lock bar  22  is pressed against casing  1  by the natural tension and resilience of lock bar  22 . To release the carrier  13  from the casing  1 , release button  20  is depressed, which moves lock bar  22  away from casing  1  and latch  23  and latch  24  away from detent  15 . Carrier  13  can then be disengaged from casing  1 . 
     Detent  15  is shaped to accommodate the configuration of latch  23  and latch tip  24 . In a preferred embodiment, latch  23  is angled as shown to provide a conventional catch mechanism. 
     Detent  15  includes base  15 A which may be generally flat or angled to accommodate latch  23 . Detent  15  also includes side  15 B which is designed to accommodate and mechanically couple with latch  23  and latch tip  24 . Detent  15  may, instead, have two parallel sides on either side of base  15 A. 
     The pressure of lock bar  22  against casing  1  at detent  15  will maintain carrier  13  in the operative position until a user activates release button  20 , moving it from the resting position shown in FIG. 4B to a released (depressed) position  20 ′ shown in FIG.  4 C. Once the release button is moved and latch tip  24  is removed from detent  15  at least far enough so that carrier  13  can slide freely, the user can move carrier  13  away from casing  1 . Although conducting sleeves  16  shown in FIG. 5 may remain hot electrical leads after carrier  13  is removed, a user or passerby is protected from inadvertent contact with the conducting pins by their submerged position relative to the carrier  13 . 
     Collapsible Prong Plug Feature 
     The collapsible prong plug feature of this invention includes a securing means and a release mechanism integrated into the carrier. The prongs can be modified to accommodate specific design needs, including the number and configuration of electrical prongs to adapt to a variety of standard electrical outlets. FIGS. 6,  7  and  8  illustrate a representative device, but one skilled in the art will recognize that a variety of devices can be designed and manufactured which are encompassed by the teachings of this invention. 
     Referring to FIG. 6, an exploded view of carrier  13  including the collapsible prong feature of the present invention is shown. Cover plate  50  including lock bar  22  integrally formed therewith, is connected to carrier  13 . Encased between cover plate  50  and carrier  13  are collapsible prongs  41  integral with pivot pin  42 . Pivot pin  42  rests between upper half-axis  48  and lower half-axis  49 . Securing contact springs  45  sit between collapsible prongs  41  and carrier  13 . There is preferably at least one securing contact spring for each prong  41 . Thus, for the embodiment shown there are two securing contact springs  45 . 
     FIG. 7 provides a more detailed exploded view of the present invention. Male connectors  51  are designed to mate with female connectors  47  in cover plate  50 . Securing contact springs  45  preferably fit around male securing members  51  and are thereby secured into position by downward pressure applied from cover plate  50  via female connecting members  47 . Gap  55  is formed in carrier  13  to accommodate movement of integral lock bar  22  in cover plate  50 . 
     FIGS. 8A,  8 B and  8 C illustrate cut-away, side views of a preferred embodiment of the new device. Carrier  13  includes connecting line  57  attaching conducting sleeves  16  to each of collapsible prongs  41 . Note that each of the sleeves  16  is encased in the carrier  13 , which is made of insulative material, so that each sleeve  16  is substantially shielded along its length in a substantially nonconductive jacket having an opening at one end to permit engagement with one of the conducting pins  25 . Collapsible prongs  41  are integrally formed with pivot pin  42 . Also integral with pivot pin  42 , cans  44  provide an offset force when the prongs are extended. Referring to FIG. 8B, as collapsible prongs  41  are raised, cams  44  engage rises  46  in securing contact springs  45 , thereby causing a frictional force to resist the upward motion of the collapsible prongs. As collapsible prongs  41  reach their full upright and extended position, cams  44  pass completely over rises  46  and are engaged within securing contact spring  45 . An unbroken electrical connection is thereby created from collapsible prongs  41  through cams  44  to securing contact springs  42  to wires  57  and to conducting sleeves  66 . 
     If desired, a single cam could be placed on pivot pin  41  with a single securing contact spring  45  positioned nearby to provide resistance via rise  46  and electrical contact with conducting sleeves  66 . 
     A typical collapsible prong plug includes two or three prongs  41 . The figures illustrate a typical American plug, but the same teachings and principles can be applied to design and use collapsible prong plug devices for British, European or other plugs, as illustrated in FIG.  1 . 
     The pressure of securing contact springs  45  will maintain collapsible prongs  41  in the extended position until a user forces the prongs from the extended position shown in FIG. 8C to the collapsed position shown in FIG.  8 A. The user must apply sufficient force to move each cam  44  over rise  46 , thereby increasing the resistant force of each securing contact spring  45 . As cams  44  of prongs  41  disengage securing contact springs  45 , electrical contact is broken. Once the cams  44  have passed rises  46  and are free of securing contact springs  45 , the user can move prongs  41  to the collapsed position. 
     Thus, the preferred embodiment of the present invention incorporates the collapsible prong feature into an interchangeable plug incorporating a submerged pin and sleeve electrical connection. With this combination, the present invention provides an improved apparatus and method for deriving electrical current from an outlet meeting any national or international standard, while providing the increased safety and convenience of an easily stored and transported device. 
     A general description of the device and method of using the present invention as well as a preferred embodiment of the present invention has been set forth above. One skilled in the art will recognize and be able to practice many changes in many aspects of the device and method described above, including variations which fall within the teachings of this invention. The spirit and scope of the invention should be limited only as set forth in the claims which follow.