Mechanically controlled velocity extender system for antennas

#This invention relates generally to automatic extender systems for antennas, and more particularly to mechanically powered systems suitable for use in portable telecommunication equipment.

#Retractable antennas are commonly used in mobile telecommunication equipment such as portable telephones, cellular phones and two-way radios. Typically, retractable antennas used in mobile telecommunication instruments require two-handed operation for extension. For example, when answering a call on a cellular phone, the user must open the flip-open cover, if so equipped, pull out the antenna with one hand while holding the phone in the other hand, push a button to answer the call, then speak. This multiple step operation is cumbersome, particularly if the user is carrying another article or is otherwise impaired from using both hands to extend the antenna.

#Several arrangements have been proposed for powering the extension of the antenna on small, mobile telecommunication instruments. Electrically powered, motor driven antenna extenders, such as those found on vehicles and larger communication instruments, are undesirable for small instruments because of the space requirements for the motor and drive mechanisms, the resultant added weight and cost, and the significant current draw on a limited power source, i.e., the batteries of the instrument.

#FIG. 1 is a cross-sectional view of the preferred embodiment of an extension system for an antenna, embodying the present invention, showing the antenna in an extended position;

#FIG. 2 is a three-dimensional view of the preferred embodiment of an extension system for an antenna, embodying the present invention, showing the antenna at an intermediate position;

#FIG. 3 is a schematic view of an alternative embodiment of an extension system for an antenna, embodying the present invention, showing the antenna at a retracted position; and,

#In the preferred embodiment of the present invention, an extension system 10 for an antenna 12 that is movable between an extended position, as shown in FIG. 1, to a retracted position. includes a body member 14, such as the case or frame of a cellular or portable phone which supports the antenna 12 when in the extended position, and protectively encloses the antenna 12 when retracted. Desirably, the antenna 12 is maintained at the retracted position by an easily operable antenna release means 15 that is selectively operable, such as a spring loaded latch 16 described below in more detail.

#The antenna extension system 10 embodying the present invention includes a means 18 for applying a bias force on the antenna 12 in a direction which always urges the antenna toward the extended position. When the antenna release means 15 is activated to release the antenna 12 from the retracted position, the means 18 for applying a bias force moves the antenna 12 from the retracted position to the extended position, and maintains the antenna 12 at the extended position until the antenna 12 is retracted by manually pushing the antenna 12 into the body member 14.

#In the preferred embodiment of the present invention, the means 18 for applying a bias force comprises a constant force spring 20, such as a flat strip wound to form a coil which maintains essentially the same diameter as one end of the spring is unrolled from the coil. Constant force springs provide a bias force having a constant value regardless of deflected position or displacement. The constant force spring 20 has one end at the center of the coil that is rotatably attached to the body member 14, such as by a short spool 22, and an extendable end 24 that is attached to the lower, or proximal end of the antenna 12. Such springs are commercially available, in almost any length, width and force rating, such as the CONFORCE.TM. line of springs produced by Vulcan Spring & Mfg. Co., Telford, Pa. Alternatively, the means 18 for applying a bias force may comprise a variable rate spring having the same shape and form as the constant force spring 20, or other suitable construction.