Torsional hinging mechanism

A wireless communications device, such as a cellular telephone, is provided with a torsional hinging mechanism for rotatably coupling a flip cover to the device's main body. The torsional hinging mechanism both minimizes lateral loading and causes the flip cover to automatically assume the open position when released. One, and preferably two, torsional axles interconnect the main body to the flip cover. One end of the torsional axle is engaged by the main body so as to prevent relative rotation therebetween, for example by fitting the end through a retaining slit in the main body. The opposite end of the torsional axle is engaged by the flip cover so as to prevent relative rotation therebetween, for example by fitting a keyed end into a keyed hole. When the flip cover is in the closed position, the torsional axle is rotationally loaded so as to urge the flip cover towards the open position. Optionally, the one or more of the torsional axles may include an acoustic passage for acoustically connecting the flip cover to a microphone in the main body when the flip cover is in the open position.

FIELD OF THE INVENTION 
The present invention relates generally to wireless communications devices, 
and more particularly to a torsional hinging mechanism for connecting a 
movable flip cover to a main body of a wireless communications device. 
BACKGROUND OF THE INVENTION 
Wireless communications devices, such as cellular telephones, have proven 
very popular. Over time, these devices have been reduce greatly in size 
and weight. Today, it is common for a cellular phone to have a small main 
body and a flip cover coupled to the main body via a hinge mechanism. It 
is desirable for the flip cover to remain in the closed position until the 
user desires to use the device, when the flip cover is opened, exposing a 
keypad. In the open position, the device is typically long enough to 
stretch from a person's mouth to their ear. The user speaks into the flip 
cover and listens to the opposite end of the main body. Once in the open 
position, it is desirable for the flip cover to remain open until 
deliberately closed by the user. 
Due to the small size and desire for light weight, plastic parts are 
typically employed for the hinge mechanisms linking the flip cover and the 
main body. One common configuration is to use a flip cover that connects 
to the main body via two coaxial hinges. The first hinge is typically a 
simple shaft and collar arrangement that performs the dual function of 
allowing relative rotational motion and provides an acoustic coupling path 
between the flip cover and the main body. The second hinge is typically a 
simple shaft and collar arrangement without acoustic coupling 
characteristics. Further, it is typical for at least one of the hinges to 
include some sort of detent arrangement so as to hold the flip cover in a 
predetermined opened position when opened. One type of detent arrangement 
is through the use of cammed surfaces and lateral force applied through a 
common coil spring. 
The present methods of hinging suffer from two drawbacks. First, many of 
the hinge arrangements create lateral loads on the flip cover. For 
instance, the cam and spring arrangement described above produces a 
lateral load against the flip cover. Typically, such a lateral load is 
asymmetrically applied to the flip cover, because one hinge typically is 
not laterally loaded so as to allow for acoustic coupling. Due the 
asymmetrical loading, the hinge cover may not fit properly, causing 
aesthetic dissatisfaction and/or significant stress may be placed on the 
flip cover, leading to undesirable fatigue and failure. Second, the 
available hinge mechanisms do not cause the flip cover to automatically 
assume the open position. That is, the flip covers must be moved into the 
open position, rather than springing into an open position when released 
from a catch. 
In light of the above, there remains a need for a hinging arrangement that 
does not produce lateral loading and that causes the flip cover to 
automatically assume the open position when released. Further, it would be 
desirable if such a hinging arrangement optionally allowed for acoustic 
coupling between the flip cover and the device's main body. 
SUMMARY OF THE INVENTION 
The present invention provides a wireless communications device, such as a 
cellular telephone, having a torsional hinging mechanism which does not 
produce lateral loading and which causes the flip cover to automatically 
assume the open position when released. One, and preferably two, torsional 
axles interconnect the main body to the flip cover. The torsional axles 
preferably include a generally cylindrical hub having a generally flat 
section thereon and an elongate arm. The end of the elongate arm is 
engaged by the main body so as to prevent relative rotation therebetween, 
for example by fitting the end of the elongate arm through a retaining 
slit in the main body. The opposite end of the torsional axle, the hub, is 
engaged by the flip cover so as to prevent relative rotation therebetween, 
for example by fitting the hub into a keyed hole having a flat section 
which corresponds to the flat section on the hub. When the flip cover is 
in the closed position, the torsional axle is rotationally loaded so as to 
urge the flip cover towards the open position. Preferably, the main body 
includes a latch or similar means for resisting the opening force of the 
torsional axle so as to keep the flip cover in the closed position until 
released by the user. 
Optionally, the one or more of the torsional axles may include an acoustic 
passage for acoustically connecting the flip cover to a microphone in the 
main body when the flip cover is in the open position. Preferably, the 
acoustic passage enters the hub from an axial location on the end of the 
hub away from the arm and exits at a circumferential location on the 
cylindrical portion of the hub. When the flip cover is in the open 
position, this exit aligns with an opening in the main body which leads to 
the microphone.

DETAILED DESCRIPTION 
The present invention utilizes at least one, and preferably two, torsional 
axles 70 to provide rotational opening force to the flip cover 50. The 
torsional axles 70 cause the flip cover 50 to spring open to its normally 
open position when a latch 40 or other retaining means holding the flip 
cover 70 is released. In one preferred embodiment, at. least one of the 
torsional axles 70 is provided with an acoustic passage 86 which forms 
part of an acoustic pathway leading to the microphone 60. 
Referring to FIG. 1, a wireless communications device 10, such as cellular 
or satellite telephone, typically includes a main body 20 which houses the 
device's electronics. The front of the main body 20 typically includes on 
its upper portion a speaker outlet 22 and a display 24, in its middle 
portion a keypad 26 for entry of phones numbers and other control 
information, and on its lower portion a raised area 30 that extends across 
the central part of the width of the main body 20. As best seen in FIG. 2, 
beside each end of the raised area 30 (i.e. on the left and right) is are 
curved hollows 28 which extend to the edge of the main body 20. On each 
end of the raised area 30 there is a axle hole 32. As best seen in FIG. 3, 
on the underside of the raised area 30 is a cavity 34 having near its 
middle two thin ribs 36 having vertical slits 38 therein. 
Connected to the main body 20 is a flip cover 50 which, in the closed 
position, covers the keypad 26. The flip cover 50 is best seen in FIG. 1 
and FIG. 3. For ease of reference, the portion of the flip cover 50 near 
the upper portion of the main body 20 when the flip cover 50 is closed 
will be called the top and the opposite end will be called the bottom. On 
the bottom end of the flip cover 50 are two arms, one on the left 52a and 
one on the right 52b. These arms 52a,52b each include a keyed hole 54 
having a flat portion of their circumference 55 which provides the keying 
action. When the flip cover 50 is placed over the main body 20, the two 
arms 52a,52b fit into the curved hollows 28 and surround the raised area 
30 of the main body 20. Optionally associated with the arms 52a,52b may be 
suitable detents 53 which releasably engage corresponding recesses 29 on 
the adjacent portions of the raised area 30 so as to encourage the flip 
cover 50 to stop in a predetermined position when opened. 
The flip cover 50 is connected to the main body 20 via at least one, and 
preferably two, torsional axles 70. As best seen in FIG. 5, the torsional 
axle 70 includes a hub 80 and an arm 84. The hub 80 is a truncated 
cylindrical shape having a portion of its circumference being a flat 
surface 82. Preferably, the edge of the hub 80 is chamfered or otherwise 
tapered so as to facilitate the insertion of the torsional axle 70 into an 
axle hole 32 and keyed hole 54. The arm 84 is thin and elongated. In the 
preferred embodiment, the arm 84 is a metal stamping of suitable spring 
material such as beryllium copper and the hub 80 is plastic and insert 
molded around the arm 84. 
The torsional axles 70 are placed in the cavity 34 formed on the underside 
of the raised area 30 of the main body 20. The flip cover 50 is placed in 
the open position relative to the main body 20 such that the keyed holes 
54 line up with the axle holes 32. Then the hubs 80 of the torsional axles 
70 are inserted through the axle holes 32 and into the keyed holes 54. The 
flat portion 82 of the hubs 80 should align with the flat portion 55 of 
the keyed holes 54. The arms 84 of the torsional axles 70 are then 
inserted into the vertical slits 38 in the ribs 36. In this position, the 
arms 84 are straight; that is, they have no torsional load. 
When the flip cover 50 is closed, the hubs 80 are forced to rotate with the 
flip cover 50. That is, the flat portion 82 of the hub 80 stays in 
alignment with its respective flat portion 55 of the keyed hole 54 as the 
flip cover 50 is rotated. Because end of the torsional axle 70 arm 84 is 
held stationary by the vertical slits 38, there is relative rotation 
between the ends of the torsional axle 70, which the torsional axle 70 
resists. Thus, when the flip cover 50 is closed, the torsional axle 70 
generates a rotational load against the flip cover 50, urging the flip 
cover 50 to open. 
A latch 40 or other catch mechanism should be used to hold the top end of 
the flip cover 50 against the rotational force exerted by the torsional 
axle 70 when the flip cover 50 is in the closed position. Any one of a 
wide variety of latches 40 well known in the art may be used for this 
purpose. It is preferred that the latch force be in the range of 5-10 
Newtons so that flip cover 50 will be securely held in the closed 
position, but can be released without undue effort. 
To open the flip cover 50, the user releases the latch 40. The rotational 
force from the torsional axles 70 causes the flip cover 50 to rotate to 
the open position. This action can be described as springing open the flip 
cover 50. In this position, the flip cover 50 is ready for normal 
operation. 
It should be noted that it is preferred, but not required, for the 
torsional axles 70 to allow the flip cover 50 to be opened beyond the 
normal open position. That is, the torsional axles 70 do not need to have 
some sort of rotational stop. This is so that an open wireless 
communications device 10 may be placed upside down on a flat surface, such 
as a tabletop, and pressed flat without breaking. Thus, the design of the 
torsional axles 70 should preferably take into consideration that the arms 
84 may be flexed both forwards and backwards. 
The use of the torsional axles 70 to rotatably connect the flip cover 50 to 
the main body 20 does not apply any lateral load to the flip cover 50. 
Instead, a rotational load is applied. Thus, undesirable part-to-part 
misfits and stresses are minimized. Further, in a preferred embodiment, 
two torsional axles 70 are employed, one on each side, thereby 
symmetrically loading the flip cover 50 and allowing for continued 
operation if one of the torsional axles 70 breaks. 
In addition to their mechanical aspects, the torsional axles 70 may form a 
portion of an acoustic pathway. In wireless communications devices 10, 
such as cellular telephones, it is common for the microphone 60 to located 
in the main body 20. However, the portion of the device closest to the 
user's mouth in the normal open position is the top of the flip cover 50 
(rotated down to be furthest from the main body 20), not the main body 20. 
It is typically undesirable for the microphone 60 to be too sensitive, as 
unwanted environmental noise may be introduced. Therefore, it is desirable 
to route the sound from the top of the flip cover 50 to the bottom of the 
flip cover 50, through the hinge area, and to the microphone 60 in the 
main body 20. 
To facilitate this, the underside of the flip cover 50 typically includes a 
wedge shaped recessed area 58 that funnels down towards one arm 52a,52b or 
the other. The left arm 52a will be used for purposes of illustration. At 
the point of the recessed area 58 is a passage 59 that leads to the axial 
center of the left arm 52a. A flip insert 56 covers the recessed area 58, 
thereby forming a substantially enclosed sound chamber. The flip insert 56 
includes a plurality of voice holes 57 which allow sound waves to enter 
the sound chamber. An acoustic passage 86 through the left torsional axle 
70 routes the sound to an opening 62 in the main body 20. From this 
opening 62, the sound is routed to the microphone 60. 
The hub 80 of the left torsional axle 70 includes a curved L-shaped 
acoustic passage 86 with an entry 88 at the axial center of the hub 80 
farthest from the arm 84 and an exit 89 along the circumference of the hub 
80. The exit 89 is circumferentially located in relation to the flat key 
portion 82 of the hub 80 such that the exit 89 is aligned with the opening 
62 in the main body 20 when the flip cover 50 is in the normal open 
position. Preferably, the acoustic passage 86 is a constant diameter and 
any curves in the acoustic passage 86 have a gentle constant radius. 
When the flip cover 50 is closed, the exit 89 will not be aligned with the 
opening 62. Thus, the microphone 60 should not be receiving sound energy 
from the acoustic pathway. Neither should the microphone 60 be receiving 
sound energy from the acoustic pathway 86 when the flip cover 50 is opened 
beyond its normal open position, because, when opened beyond its normal 
open position, the exit 89 should be rotated out of alignment with the 
opening 62. 
A wireless communications device 10 may be constructed according to the 
present invention with the following: 
A main body 20 having a raised area 30 of 33 mm and 3.5 and having axle 
holes 32 of 4.7 mm diameter on each end and ribs 36 of 3 mm thickness and 
0.25 mm wide slits 38. 
Two torsional axles 70 having hubs 80 of 4.5 mm diameter, tapered at 
approximately 5 degrees and a length of 4 mm and having a flat portion 82 
of twenty to thirty degrees; the torsional axles 70 having arms 84 of 25 
mm.times.0.25 mm dimensions made from stainless steel insert molded into 
the hubs 80; at least one of the torsional axle hubs 80 having an acoustic 
passage 86 of 1 mm diameter and a 90.degree. turn of 1 mm radius; 
Keyed holes 54 of 4.6 mm diameter in the flip cover 50, having flat 
portions 55 of twenty to thirty degrees. 
The present invention may, of course, be carried out in other specific ways 
than those herein set forth without departing from the spirit and 
essential characteristics of the invention. The present embodiments are, 
therefore, to be considered in all respects as illustrative and not 
restrictive, and all changes coming within the meaning and equivalency 
range of the appended claims are intended to be embraced therein.