Hinge apparatus having a self-latching hinge shaft for foldable radiotelephones

A hinge apparatus rotatably couples about an axis of rotation (303) a body portion (101) and a flip element (103) of a foldable radiotelephone (100). The hinge apparatus includes a hinge shaft (205) having an unlatched and latched position on the axis of rotation (303) relative to the body portion (101). The hinge shaft (205) may be removeably latched to a front housing portion (231) of the body portion (101) wherein the hinge apparatus may be tested before final assembly of the foldable radiotelephone (100). The hinge shaft (205), accessible through a slot (245) in the body portion (101), may be removeably latched from the outside of the body portion (101).

FIELD OF THE INVENTION 
This invention relates generally to hinged housings for miniature 
electronic equipment and more particularly to foldable radiotelephones 
which utilize hinged housings for folding elements. 
BACKGROUND OF THE INVENTION 
Portable, cellular phones are increasingly utilized to permit a user to 
communicate telephonically over a wireless system at virtually any 
location. The portable telephone transmits a low wattage, radio frequency 
signal to a receiving station whereat connections are provided with 
conventional telephone systems. Numerous receiving stations are spaced 
apart at fixed locations in an area to receive the signals transmitted by 
the portable telephone as the portable telephone is relocated throughout 
the area. 
Telephones utilizing two housing elements connected with some type of 
hinging mechanism, are common in wireline telephone sets and landline 
wireless extension phones and have become more common in portable cellular 
radiotelephones. This folding arrangement allows for the telephone to be 
more compact when the two housings are foldable upon themselves. 
Radiotelephones which utilize this type of design usually have most or all 
of the electronics within the larger of the two housings, herein after 
called the body portion. The smaller housing will hereinafter be called 
the flip element. 
A variety of hinge mechanisms have been used to rotatably couple the flip 
element to the body portion. One such hinge mechanism was described in 
U.S. Pat. No. 4,897,873 by Beutler et al.. Beutler discloses a hinge 
mechanism having two essentially cylindrical hinge shafts rotatably 
coupling the flip element to the body portion. The assembly of Beutler's 
hinge mechanism, however, is both clumsy and time consuming. The hinge 
assembly also requires a spacer which snaps into the body portion to 
separate the hinge shafts thereby maintaining them in their properly 
assembled position. 
The body portion of the telephone usually has a front and a rear housing 
portion which mate together to form the body portion. Beutler describes 
the flip element primarily residing in the front housing portion. During 
the assembly of the telephone in a factory, it is desirable to test the 
hinge mechanism portion rotatably coupling the flip element to the front 
housing portion before the front and rear housing portions are mated 
together. Accomplishing this test procedure requires that the hinge shafts 
are separated by the spacer snapped to the front housing portion. After 
the test procedure is completed, the spacer must be removed before the 
rear housing can be assembled to the front housing wherein the spacer may 
again be snapped into place. Before the spacer is snapped into place, the 
hinge shafts are free to move out of position thereby yielding a clumsy 
and time consuming assembly process. 
A formidable challenge would be to design a hinge mechanism conducive to 
convenient operator assembly wherein the flip element portion may be 
tested with the front housing portion only and thereafter assembled with 
the rear housing portion without the need of an additional spacer to 
secure the hinge shafts in their proper position. 
SUMMARY OF THE INVENTION 
According to one aspect of the present invention, a foldable radiotelephone 
comprises first and second housing portions, a first hinge shaft and a 
first spring arm. The first hinge shaft rotatably couples the first and 
second housing portions about an axis of rotation. The first hinge shaft 
has lateral surfaces and a circumferential surface. The first spring arm 
is integrally formed with the first hinge shaft and is disposed parallel 
to the axis of rotation. The first spring arm has a first end attached to 
a lateral surface of the first hinge shaft and has a second end disposed 
in free space. The second end of the first spring arm is permitted to flex 
in a direction substantially perpendicular to the axis of rotation. The 
first spring arm latches the first hinge shaft and the first housing 
portion when the first hinge shaft is moved to a first axial position on 
the axis of rotation and unlatches the first hinge shaft and the first 
housing portion when the first hinge shaft is moved to a second axial 
position on the axis of rotation. 
According to a further aspect of the present invention, the foldable 
radiotelephone further comprises a hinge cavity and a hinge knuckle. The 
hinge cavity is provided in the first housing portion. The hinge knuckle 
is coupled to the second housing portion and is disposed within the hinge 
cavity. The first hinge shaft extends through an aperture provided in the 
hinge knuckle. 
According to a further aspect of the present invention, the first housing 
portion of the foldable radiotelephone further comprises first and second 
partial housing portions. The first hinge shaft interlocks the first 
partial housing portion and the second housing portion about the axis of 
rotation when the first hinge shaft is moved to the second axial position. 
According to a further aspect of the present invention, the foldable 
radiotelephone further comprises mutual contacting structural means, 
provided with the first housing portion and the first hinge shaft, for 
positioning a rotational orientation of the first hinge shaft about the 
axis of rotation when the first hinge shaft is moved to the first and 
second axial positions. 
According to a further aspect of the present invention, the foldable 
radiotelephone further comprises a protrusion, a hinge cavity and a rib. 
The protrusion is disposed on a free end of the spring arm and is disposed 
essentially perpendicular to the axis of rotation. The hinge cavity is 
provided in the first housing portion. The rib is provided on a wall of 
the hinge cavity and is disposed essentially perpendicular to the axis of 
rotation and adjacent to the protrusion of the spring arm. The spring arm 
deflects when the protrusion makes interfering contact with the rib when 
the first hinge shaft is moved between the first and second axial 
positions to allow the protrusion to be repositioned on an opposite side 
of the rib. 
According to a further aspect of the present invention, the foldable 
radiotelephone further comprises a second hinge shaft and a second spring 
arm. The second hinge shaft rotatably couples the first and second housing 
portions about the axis of rotation. The second hinge shaft has lateral 
surfaces and has a circumferential surface. The second spring arm is 
integrally formed with the second hinge shaft and is disposed parallel to 
the axis of rotation. The second spring arm has a first end attached to a 
lateral surface of the second hinge shaft and has a second end disposed in 
free space. The second end of the second spring arm is permitted to flex 
in a direction substantially perpendicular to the axis of rotation. The 
second spring arm latches the second hinge shaft and the first housing 
portion when the second hinge shaft is moved to a first axial position on 
the axis of rotation and unlatches the second hinge shaft and the first 
housing portion when the second hinge shaft is moved to a second axial 
position on the axis of rotation. 
According to a further aspect of the present invention, the foldable 
radiotelephone further comprises a removable spring member, disposed 
between the first and second hinge shafts, for assuring that the first and 
second hinge shafts are latched in their second axial positions. 
According to a further aspect of the present invention, the removable 
spring member of the foldable radiotelephone is disposed in an outwardly 
open slot of the first housing portion.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT 
A portable radiotelephone unit 100 adapted for use in a radiotelephone 
system is shown in FIGS. 1a and 1b. The portable unit 100 includes two 
readily apparent portions, a body portion 101 and a flip element portion 
103. The present invention is located in a hinge portion 113 of the 
radiotelephone which rotatably couples the flip element 103 to the body 
portion 101. The drawing of FIG. 3 shows the flip element in an "open" 
position such that a user of the portable unit may listen via earpiece 105 
and may speak into a microphone 107. The keypad 109 consists of a 
plurality of buttons numbered 1 through 0, # and *, in a familiar 
telephone arrangement. The keypad 109 may also have additional function 
buttons such as volume control and other buttons associated with telephone 
number recall. An antenna 111 enables wireless communication between the 
portable unit and a remote base site. 
When the flip element 103 is open as shown in FIG. 1a and 1b, the portable 
unit can be in a state of answering or making a telephone call. Such a 
state is commonly known as "off-hook". Upon completion of a telephone 
call, the user may hang up the portable unit by moving the flip element to 
a closed position. The flip element in the closed position is commonly 
known as "on-hook". This hanging-up may be accomplished by causing the 
flip element 103 to rotate about the axis of the hinge portion 113 so that 
the flip element portion 103 rests against the keypad 109. This action 
activates a "hook-switch" which causes the telephone call to be 
terminated. In the closed position the portable unit 100 is in a standby 
state ready to receive an incoming call. Upon receiving an incoming call, 
the flip element 103 may be rotated about the axis of the hinge portion 
113 to its open position thereby activating the "hook-switch" which 
enables the radiotelephone to answer the call. 
In the preferred embodiment of the present invention, the flip element 103 
is held in the open or closed position by a combination of elements shown 
in FIG. 2. A detent follower 201 is placed within a hinge knuckle 203 and 
forced against a cylindrical hinge shaft 205 by a resilient medium such as 
a spring 209. The spring 209 is formed from a flat curved piece of steel 
having a first end 211 hooked against a projection 213 in a space 214 
within the flip element 103. The center portion of the spring 216 presses 
against a post 215 such that a second end of the spring 217 forces the 
detent follower 201 through an aperture 219 into the hinge knuckle 203. 
The design of the hinge shaft 205 allows the flip element 103 to be held 
against the keypad 109 in the on-hook or closed position and at an obtuse 
angle (for example, 150.degree.) in the off-hook or open position. A 
magnet 221 within the flip element 103 generates the hook-switch control 
signal in the body portion 101 responsive to the rotational orientation of 
the flip element with respect to the body portion. A cover 233 conceals 
the spring 209, and the magnet 221 within the space 214 of the flip 
element 103. 
A second hinge shaft 225, having essentially the same features and shape as 
a first hinge shaft 205, is disposed within a second hinge knuckle 227. 
The hinge knuckles, 203 and 227, of the flip element are located within 
corresponding slots 233 and 235 in the hinge portion 113. Each hinge shaft 
205 and 225 are aligned and secured to the body portion 101 such that the 
hinge knuckles 203 and 227 are free to rotate about the hinge shafts 205 
and 225, respectively. 
A rear housing portion 229 is attached to the front housing portion 231 
using conventional assembly techniques. When the hinge portion 113 is 
fully assembled a first end 227 of the hinge shaft 205 is disposed within 
an aperture 228 in an upstanding wall in the front housing portion 230 and 
an aperture 232 in an upstanding wall in the rear housing portion 234. By 
interlocking the front and rear housing portions with an end of the hinge 
shaft, the structural integrity of the hinge portion 113 is preserved. 
Similarly, the second hinge shaft 225 interlocks the front and rear 
housing portions at the other end of the hinge portion 113. 
A cap 239, having a U shaped spring member 241 is attached to the rear 
housing portion 229 such that the cap covers an external connector 
aperture 243 and the U shaped spring member portion 241 is inserted into a 
slot 245. The unique purpose of the U-shaped spring member will be 
discussed with FIG. 8. 
The present invention utilizes a novel hinge shaft design enabling the 
hinge shaft to be slideably positioned to a latched and an unlatched 
position within the hinge portion 113. Thus, the aforementioned spacer 
used by Beutler is eliminated and the hinge assembly process is improved. 
The unlatched position is an assembly position in which the flip element 
103 and hinge shafts may be aligned with the hinge portion 113. The 
latched position is an interlocking an securing position which interlocks 
the front and rear housing portions 231 and 229 and secures the rotational 
orientation of the hinge shafts to the body portion 101. An advantage of 
the present invention enables the attachment of the flip element 103 to 
the front housing portion 231 without the rear housing portion 229 or the 
aforementioned spacer used by Beutler to implement a test procedure. 
Another distinct advantage of the present invention enables assembly or 
repair personnel to manually repositioned the hinge shafts between their 
latched and unlatched positions from the outside of the body portion 
through the slot 245. 
A first isometric view of the hinge shaft 205 is illustrated in FIG. 3. 
Details describing the implementation of the novel features described on 
the hinge shaft 205 will be discussed with FIGS. 5 and 6. The following 
description also applies to the second hinge shaft 225. A primary feature 
of the present invention is the novel construction of the hinge shaft. The 
hinge shaft, having an essentially cylindrically shape, includes unique 
features for aligning the flip element relative to the body portion and 
allowing the hinge shaft to be removably latched to the body portion. 
The hinge shaft is removably latched to the body portion by utilizing an 
spring arm 301 disposed parallel to a center axis 303 of the hinge shaft 
205. The spring arm has a fixed end 302 attached to the hinge shaft 205 
and a free end 304 surrounded by free space. The thickness of the material 
comprising the spring arm 301 is such that a protrusion 305, attached to 
the free end of the hinge shaft 304, is allowed to flex. The protrusion 
305 has an end portion having a radius 307 enabling the spring arm 301 to 
deflect when the end portion of the protrusion 307 encounters mechanical 
interference with another part as the hinge shaft 205 is slideably 
positioned along its center axis 303. The spring arm 301 is surrounded on 
three sides by a rectangular shaped frame 309 allowing the spring arm 301 
to move freely within the frame 309. The frame 309 is disposed essentially 
along the axis of the hinge shaft 303. The frame 309 includes a first side 
311 having a rectangular shaped notch 313 extending across the first side 
311. Likewise, the frame 309 has a second side 315 with a corresponding 
second notch 317 essentially opposite the notch 313. The first and second 
sides of the frame join a surface called a stop 321 essentially 
perpendicular to the center axis 303 which limits the axial positioning of 
the hinge shaft. 
The hinge shaft 205 includes a recess 319 which accepts the detent follower 
201 to position the flip element with respect to the body portion. The 
hinge shaft 205 also includes the elongated first end portion 227 disposed 
on the axis of rotation of the hinge shaft 303, to aid in securing the 
rotational orientation of the hinge shaft 205 along its axis of rotation 
303 and interlock the front and rear housing portions. 
FIG. 4 illustrates a second perspective view of the hinge shaft 205. FIG. 4 
is derived by rotating the hinge shaft 205 of FIG. 3 approximately 
180.degree. about the axis of rotation of the hinge shaft 303. Novel 
features of the hinge shaft 205 described with FIG. 4 will be more fully 
explained with FIGS. 5 and 6. 
Novel features illustrated in FIG. 4 include a guide 401 disposed on the 
frame of the hinge shaft 309 essentially parallel to the axis of rotation 
of the hinge shaft 303. The guide 401 includes rails 403 and 405 partially 
extending above the frame 309. The backside of the spring arm 301 may be 
viewed within the frame 309. Notches 313 and 317 may also be viewed in 
their respective sides of the frame 311 and 315. 
Another unique feature of the hinge shaft is the cut out 407 extending 
across the width of the hinge shaft 205 essentially perpendicular to the 
axis of rotation 303. The cut out 407 has a U-shaped profile extending 
partially into the hinge shaft 205. The rails 403 and 405 extend into the 
U-shaped opening of the cut out 407. 
This second perspective view also includes a recess 409 for maintaining the 
flip element in a second rotational position respective to the body 
portion. 
A cut-away view of the flip element 103 partially assembled to the body 
portion 101 is shown in FIG. 5. A primary feature of the preferred 
embodiment of the present invention is that the hinge shafts 205 and 225 
have at least two axial positions along the axis of rotation 303 of the 
hinge mechanism. The first axial position is an unlatched position and the 
second axial position is a latched position. FIG. 5 shows the hinge shafts 
in their unlatched position which is advantageously utilized to assemble 
the flip element 103 to the body portion 101. The hinge shafts 205 and 225 
are partially disposed within hinge knuckles 203 and 227, respectively. 
The hinge shaft 205 is rotationally orientated about the axis of rotation 
303 such that the cut out 407 of the hinge shaft 205 is allowed to slide 
past an overhang 501 of the front housing portion 231. The side of the 
hinge shaft 205 opposite the cut out 407 is captivated by a rib 503 of the 
front housing portion 231. The end portion of the spring arm 307 of the 
hinge shaft 205 is essentially parallel and adjacent to the rib 503 and 
also offset from the rib 503. The notch 317 of the hinge shaft 205 is 
essentially perpendicular to the axis of rotation 303. The hinge shaft 205 
is only partially disposed within the hinge knuckle 203 thereby allowing 
the end of the hinge shaft 227 to clear the upstanding wall portion of the 
front housing 230 and the upstanding wall portion of the rear housing 234. 
FIG. 6 illustrates a cut-away view of the flip element 103 secured to the 
body portion 101 responsive to the hinge shafts 205 and 225 located in a 
second axial position. In the second axial position, the hinge shafts are 
latched to the body portion 101 to secure their axial position and to 
interlock the front housing portion 231 to the rear housing portion 229. 
To locate the hinge shaft 205 in the latched position a simple tool such 
as a screw driver is inserted within the notch 317 in order to manually 
slide the hinge shaft along the axis of rotation 303. As the hinge shaft 
205 is slideably positioned the end portion of the spring arm 307 
interferes with the rib 503 thereby causing the spring arm to deflect 
towards the axis of rotation 303 and reposition itself on the opposite 
side of the rib 503. The hinge shaft 205 is latched in its second axial 
position through the interference of the end portion of the spring arm 307 
and the rib 503. 
The cut out of the hinge shaft 407 is slideably positioned within the hinge 
knuckle 203 such that the rail of the hinge shaft 403 is slideably 
positioned underneath the overhang 501. The interference between the rail 
403 and the overhang 501 secures the rotational orientation of the second 
end of the hinge shaft 511. The first end of the hinge shaft 227 is 
inserted into the upstanding wall of the front housing portion 230 and the 
upstanding wall of the rear housing portion 234 such that the front and 
rear housing portions are interlocked along the axis of rotation 303. This 
interlocking feature is necessary to maintain the integrity of the hinge 
assembly in the event that the flip element 103 is twisted relative to the 
body portion 101 along the axis of rotation 303. 
Per FIGS. 5 and 6, the preferred embodiment of the present invention 
includes a second hinge shaft rotatably coupling the flip element to the 
body portion 101 having essentially the same features as the first hinge 
shaft 205 but symmetrically disposed with respect to the first hinge shaft 
205. The advantage of symmetrical design features is that the same hinge 
shaft may be used in both locations to economize molding cycle time and 
eliminate confusion on the assembly line. The advantages and features 
described with the first hinge shaft 205 may also be interpreted for the 
second hinge shaft 225. 
FIG. 7 illustrates a cut-away view of the hinge portion described in FIG. 
6. FIG. 7 clearly identifies the means by which the rotational orientation 
of the hinge shaft is secured to the body portion. The overhang 501 and a 
ledge 701 protruding from a wall 703 comprise a channel in the front 
housing portion 231 by which the guide 401 of the hinge shaft is 
captivated on three sides. The rail 403 of the guide is essentially 
parallel and adjacent to the overhang 501. Likewise, the rail 405 of the 
guide is essentially and adjacent to the ledge 701. Additionally, the rib 
503 provides support to the side opposite the guide 401 of the hinge shaft 
205. The guide 401 disposed within the channel 703 in combination with the 
rib 503 supporting the hinge shaft 205 secure the rotational orientation 
of one end of the hinge shaft. Means by which the rotational orientation 
of the first end of the hinge shaft is secured includes the elongated 
portion of the hinge shaft 227 disposed within an aperture having 
essentially the same shape but slightly larger than the elongated shape of 
the hinge shaft disposed within the upstanding walls of the front and rear 
housing portions. 
An end view of the radiotelephone having the flip element 103 in its closed 
position relative to the body portion 101 is illustrated in FIG. 8. The 
hinge shafts 205 and 225 are located in their latched position along the 
axis of rotation 303. The hinge shafts 205 and 225 are latched to the body 
portion in the second axial position thereby eliminating the need for the 
aforementioned spacer used by Beutler disposed between the hinge shafts in 
the hinge portion. The spring member of the cap 241 is disposed within the 
slot of the rear housing portion 229 such that the spring member fills the 
space in the hinge portion between hinge shafts 205 and 225 and secures 
the cap into place. The disposition of the spring member 241 is not 
necessary for proper assembly of the hinge shaft mechanism. The purpose of 
the spring member 241 is to assure that the hinge shafts 205 and 225 are 
properly latched to the body position 101. Once the radiotelephone is 
given to a customer the cap may be removed or lost without effecting the 
operation of the hinge mechanism. 
FIG. 8 clearly exemplifies how the first end of the hinge shaft 227 
interlocks the upstanding wall of the rear housing 234 to the upstanding 
wall of the front housing 230. 
Therefore, a hinge mechanism for radiotelephone has been shown and 
described. This novel hinge apparatus eliminates the need for a separate 
spacing element necessarily used to separate the two hinge shafts during 
testing of the hinge assembly and final assembly by incorporating a unique 
self-latching hinge shaft.