Magnetically operated switch lock and key therefor

#This invention relates in general to magnetically operated locks and more particularly, to an improved and more economical magnetically operated lock for use in controlling a coaxial switch.

#Cable antenna television commonly known as CATV can employ the coaxial switch at the subscriber location for either connecting the CATV line to the subscriber line or to ground through a characteristic impedance termination. The switch is usually located on a support external to the subscriber's premises and, once installed, is available for operation by a serviceman for either connecting or disconnecting the CATV line to the subscriber line, depending on whether the service is desired or not or has been paid for.

#In one form of switch arranged to prevent unauthorized operation or tampering, an enclosure having a pivot arm, including magnetically susceptible material, and carrying a magnet, closes a reed switch when the arm and magnet are in one position. The pivot arm has a series of openings in which a locking tab may engage to lock the arm. When a key containing a magnet is placed on the enclosure, the arm is lifted from the locking tab and the magnet in the key is then moved to pivot the arm and its magnet away from the switch for example, and on removal of the key and its magnet, the locking tab or detent can engage one of the holes in the pivot or lever arm. This arrangement has several disadvantages since it is relatively expensive and may be operated by unauthorized personnel through use of a single magnet since apparently no code is required and in addition, creates problems in ensuring proper location of the pivot arm relative to the switch and locking tab.

#FIG. 1 is an exploded view partially broken away of the lock and switch assembly and the key associated therewith.

#FIG. 2 is a front elevational view of the switch and lock assembly with the lock housing partially broken away.

#FIG. 3 is a sectional view taken generally along the line 3--3 in FIG. 2.

#In FIGS. 1 and 2 of the drawings, a coaxial switch and magnetic lock assembly incorporating the principles of the present invention is indicated generally by the reference character 10. The assembly 10 includes a lock assembly 12 carried in an enclosure or housing 14 and a coaxial switch assembly 16 carried in an insulating or plastic enclosure or switch housing 18 seen in cross section in FIG. 3. The housing 14, which is secured in overlapping relationship to the front, top and side surfaces of housing 18, is also of a non-magnetic material such as plastic or of diecast metal, for example, and is provided with apertured ears 20 projecting in opposite longitudinal directions for mounting of the assembly 10 on a support structure.

#The housing 18 has a cavity 22 in which are located spaced center contacts or terminals 24, 26 and 28, best seen in FIGS. 1, 6 and 7 of respective coaxial terminal assemblies 30, 32 and 34. Terminal assemblies 30 and 32 include a respective annular outer portion 36 projecting from the cavity 22 and external to the housing 18 for securing to the external conductor of a coax cable thereto with the center conductor of the coax cable projecting into housing 18 to engage the respective center terminals 24 and 26. Terminal assembly 34 is provided with a conventional outer stud portion 38 projecting from the cavity for connection to ground and is connected to its center contact or terminal 28 through a characteristic 756 ohm impedance R located in the cavity 22.

#The terminal assembly 32 serves, for example, as an input terminal from an external CATV line while terminal assembly 30 serves to connect an input line to the subscriber's television set or other appliance. The stud portion 38 of terminal assembly 34 serves as a conventional grounding terminal through the characteristic impedance, when it is desired to disconnect the subscriber's line from the CATV line. The outer conductors of the coax cables are connected to ground through a strap 39, which connects portions 36 to stud 38. Shielding for the terminal assemblies may be provided by either fashioning one of the housings of non-magnetic metal or providing a metal shield in one of the housings in overlapping relationship to the terminals.