2. RELATED ART "Flip"phones are well known in the cellular telephone and other portable communications device field. The cover, door, or"flip"protects the keypad and face of such a device when it is not in use. Opening the flip both uncovers the keypad for use and also normally activates the phone to receive or to prepare to send a call.

Opening the flip also positions the microphone input of the device farther from the ear piece, so as to be nearer the user's mouth even in a very compact device. Other devices have microphones on stalks that can be extended from the body of the phone into one or more use positions, held by spring detents in any of such positions.

It is known to have the flip of a phone positively positionable in closed and in open positions, via a spring and detent system interpose between the flip and the body of the device on a hinge axis. Such devices have typically used either a coiled metal spring, a bent metal spring, or the strength and resilience of the plastic in the

flip itself to force a detent member carried translatably in the body against a cooper- ating part in the pivoting flip at the hinge axis. Moving the flip from one stable posi- tion to the other requires the detent member to disengage from first set of surfaces in the cooperating part against the spring force and then to re-engage with a second set of surfaces in the second position. This arrangement provides a simple, long-lived detent arrangement. However, a device with a coiled or bent metal spring is difficult to assemble and to service. The metal spring takes up considerable space in the body along the hinge line and also is costly. Engineering and building the flip with proper resilience in the bridge between the ends of the hinge line is exacting and intricate work, which increases both design and quality checking costs. No use of other mate- rials in the spring system of such a device is known, apart from plastic springs molded to the shape and serving the same purpose as metal springs. Bulk com- pressible materials such as foam rubber are known to have resilient properties usable for other purposes.

SUMMARY OF THE INVENTION The present invention replaces the coiled or bent metal spring or the sensitive flip design with a simple, resilient, bulk compressible material of much reduced size, cost, and weight. The compressible bulk material may be of open cell polyurethane foam; foam rubber available under the brand name Porion is particularly favored in this use. Such Poron-brand foam rubber has little compression set and, if proper density and firmness are chosen for the application, the spring has a favorable force/deflection curve. The bulk material is punched from a sheet in, for instance,

cylindrical plugs, and one or both ends of the material can be adhered to the body and/or to the detent member along the hinge line in order to simplify assembly of the device.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an exploded perspective view of the front body panel of a cellular telephone with known flip, hinge axle, and detent members shown together with the bulk material spring of the present invention; Fig. 2 is a cross-sectional view along the hinge line of a prior art device showing the parts used with a known coiled metallic spring; and Fig. 3 is a cross-sectional view along the hinge line of a device of the present invention showing a bulk material spring according to one form of the invention.

THE PREFERRED EMBODI1\1ENTS The present invention replaces a coiled metal spring 10 mounted on a hinge axis 12 of a door, cover, or"flip"14 on the front 16P of a cellular phone or like communications device known in the prior art (as shown in Fig. 2). Instead, a shorter, lighter, less costly spring 20 is formed from a compressible, resilient bulk material, such as an open-cell polyurethane foam rubber (shown in Figs. 1 and 3).

The known hinge pin 18, the detent member 22, and the cooperating part 24 on the flip 14 of the known cellular phone face 16P may be unchanged. The spring chas- ber 26P in the body 28P of the face 16P along the hinge line 12 of the known devices can be greatly reduced in size, as to 26 in Fig. 3, because of the changed material used for the new spring 20. Ends 30,32 of the bulk material spring 20 can be ad-

WO 99/27694 PCT/US98/22718 hered respectively to the body 28 of the phone face 16 along the hinge axis 12 and/or to the detent member 22 to ease and improve the assembly process.

In particular, the detent member 22 in a flip phone may move about 1.5 mm along the hinge axis from one stable position on the cooperating part 24 to an inter- mediate position, before returning to the other stable position on that part, holding the flip relatively firmly in desired closed or open positions. That 1.5 mm motion must be accommodated while applying sufficient force on the detent member 22 to keep the flip 14 firmly in either of its selected positions. Therefore, the dimensions and other characteristics of a bulk material spring 20 can be selected to apply such a force on a predominately linear part of its compression force deflection curve. Such a curve is available for each commercial material, or one can be experimentally deter- mined. For the compressible bulk material trademarked as"Poron", by Rogers Corporation of Rogers, CT, curves are available for each of the densities and firm- nesses in which the material is made.

In one presently preferred form of the invention, a compression spring 10 in a flip phone face 16P is replace with a"Poron"bulk material cylinder 20 of 4701- 12-30 pcf material ("very high modulus"), having a 4.8 mm (3/16 inch) length before being compresse and a 5 mm (3/16 inch) diameter. This cylinder 20 is punched from a sheet of open cell foam rubber of 4.8 mm (3/16 inch) uncompressed thick- ness. The cylinder 20 exerts a 14 newton (3.1 pound) force against the detent mem- ber 22 when compresse to 65% of its original thickness and installe in the spring chamber 26 of the body 28 of the phone face 16, according to the present invention.

Although not shown in the drawings, the body 28 of the phone face 16 can be further

WO 99/27694 PCT/US98/22718 reduced in size by recapturing the space formerly used by the larger spring chamber 26P of the prior art.

Employing this invention, the hinge pin 18 could be replace by a second detent member 22 cooperating with a second cooperating surface 24 in the flip 14.

Alternatively, the detent and cooperating surfaces may be interchanged, so the mov- ing detent is in the flip and the cooperating surfaces in the body, without departing from the principles of this invention.

Ends 30 and 32 of the spring 20 may optionally be adhered with an acrylic or acrylic blend pressure sensitive adhesive to the body 28 of the cell phone in the spring chamber 26 and/or to the detent member 22, respectively, prior to assembly of the flip 14 onto the phone body 28. Using such adhesive can ease assembly proce- dures by holding the parts together until assembly and allow any needed disassembly of the flip 14 from the phone body 28..

In use, the detent member 22 is held in the position shown in Fig. 3 by the detent spring 20 when the flip 14 is in its closed position on the cell phone body 28.

When the flip 14 is pivoted by a user from the closed position of Fig. 1 or 3 to an open position (not shown), the detent member 22 will be moved to the left in the body 28, within the spring chamber 26, by the surface 24 on the flip 14. The detent member 22 will move along the hinge axis 12. It will not rotate significantly due to a cooperating key (not shown) on the detent 22 and a keyway structure 34 in the body 28, shown in Fig. 1. This movement further compresses the spring 20. After the detent 22 has moved fully to the left, past a highest point or line of the cooperating part 24 in the flip 24 at the hinge axis 12, the spring 20 moves the detent 22 back to

the right, to seat in a second stable position of the detent member 22 upon the surface of the cooperating part 24. The flip is stable in that open position due to the forces on the detent 22 exerted by the spring 20. Moving the flip to its closed position causes the parts to move again, in a similar manner, unseating and then re-seating the detent 22 into the first position on the cooperating part 24.

Similar adaptations can be made for using this invention in a microphone arm or other part of a communications device.

Variations in the dimensions and materials used will not depart from the scope and spirit of the invention. Reversa of parts and duplication of parts are also part of the invention. All such variations as come within the scope of the appende claims come within the scope of this invention.