Description of the Related Art: Portable electronic devices are employed in a variety of demanding applications including wireless phones, laptop and palmtop computers, and cameras. Such applications often require durable, lightweight, space-efficient, and cost effective devices and associated components.

Many portable electronic devices, such as flip-phones, have a rotational member that is connected to a body of the device via a clutch hinge. The clutch hinge allows manual rotation of the rotational member to various angular positions to facilitate storage and use of the associated device. Existing clutch hinges are often relatively bulky and expensive, which increases device cost.

Existing clutch hinges, such as face cam clutches, typically allow for discreet positioning of the accompanying rotational members. One such clutch hinge includes a spring-loaded face cam and cam follower fitted within a cylindrical device hinge housing. The face cam is rigidly connected to the rotational member, such as a flip portion of a wireless phone. The face cam and cam follower have facing ridges that allow for discreet positioning of the rotational member. When a torque is applied to the rotational member, a corresponding torque is applied to the face cam, which causes the face cam to rotate and lock into discreet positions with respect the cam follower. As the face cam rotates, the cam follower compresses or decompresses the spring as the ridges of the cam follower ride on ridges of the face cam. The cam follower

remains rotationally rigid with respect to the device hinge housing but axially translates to compress and decompress the spring. Unfortunately, such movement can cause unacceptable wear on device hinge housings, which are often made from relatively non-durable materials.

Many electronic device hinge housings are fabricated from ABS or ABS- PC plastic for cost, aesthetic, and design reasons. Such plastics however, often provide insufficient durability for face cam clutches, which must often withstand over 30,000 cycles.

Many conventional face cam clutches require an additional clutch housing to increase the durability of the face cam clutch. The additional clutch housing facilitates spring-loading of the face cam and cam follower, secures the face cam clutch to the device hinge housing, and limits wear between the face cam clutch and the accompanying device housing while allowing the cam follower to axially translate within the additional housing. The additional clutch housing is stationary with respect to the less durable device hinge housing, which helps to reduce wear. Unfortunately, the additional clutch housing has many shortcomings.

The additional clutch housing must be manufactured from durable, relatively expensive materials, which are often unsuitable for very thin-walled designs and are difficult to color. As a result, face cam clutches that employ the additional housing are often excessively bulky and expensive.

The additional housing may add more than 2 millimeters to the diameter of the hinge. Consequently, the additional may cause more than a 10 percent increase in the thickness of an accompanying wireless phone that is 20 millimeters thick. As wireless phones and portable electronic devices become smaller, the additional housing becomes more problematic.

The additional housing may also necessitate the use of a smaller diameter face cam clutch. The narrower clutch must withstand larger tangential forces to handle the same torque requirements as a wider face cam clutch. Consequently, the face cam and cam follower must often be made of more durable and expensive materials. In addition, the design may require a narrower and thicker spring, which may also increase the cost of the clutch.

The additional clutch housing also requires relatively high-tolerance slots in which protrusions, i. e., keys on the cam follower must slide, thereby rotationally fixing the cam follower relative to the additional clutch housing and allowing the cam follower to translate along a longitudinal axis of the clutch. The requisite tolerances represent additional design and manufacturing costs.

Hence, a need exists in the art for a space-efficient, durable, and cost- effective face cam clutch that allows for discreet positioning of a rotational member of an electronic device about the body of the electronic device.

SUMMARY OF THE INVENTION The need in the art is addressed by the space-efficient and cost-effective face cam clutch of the present invention. In the illustrative embodiment, the inventive clutch is adapted for use with a portable electronic device and facilitates the positioning of a rotational member of the portable electronic device about the housing of the device. The clutch includes a first mechanism that provides varying degrees of tangential resistance about an approximately cylindrical hinge housing and includes a face cam. A second mechanism rigidly secures the face cam to the cylindrical hinge housing and thereby secures the first mechanism to the hinge housing.

In a more specific embodiment, the second mechanism includes a protrusion on an exterior surface of the face cam. The first mechanism further includes a cam follower, a drive pin, a spring, and a mechanism for retaining the face cam, the cam follower, the spring, and the drive pin in a spring-loaded state. The drive pin includes a first end and a second end. The first end has a mechanism for connecting the drive pin to the rotational member. The second end has a mechanism for positioning the drive pin relative to the cam follower so that the drive pin is rotationally rigid and axially translatable relative to the cam follower. The spring-loaded state includes a first potential energy state

and a second potential energy state corresponding to a first rotational position of the drive pin and a second rotational position of the drive pin, respectively.

The novel design of the present invention is facilitated by the second mechanism, which includes a protrusion on the face cam for securing the face cam to the hinge housing. By securing the face cam to the hinge housing and allowing the cam follower to translate relative to the drive pin instead of allowing the face cam to translate relative to the hinge housing, wear caused by the relative movement of adjacent and dissimilar materials is reduced, which obviates the need for an additional bulky and expensive clutch housing. The protrusion on the face cam that secures the face cam and the clutch to the hinge housing also provides for easy and inexpensive installation by allowing the face cam to be in-expensively slip-fit into the hinge housing.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view of a conventional face cam clutch.

FIG. 2 is an exploded view of a face cam clutch constructed in accordance with the teachings of the present invention.

FIG. 3 is a diagram of the face cam clutch of FIG. 2 assembled.

FIG. 4 is an exploded view of a unique clutch hinge of the present invention adapted for use with a wireless phone and employing the face cam clutch of FIG. 2.

FIG. 5 is an exploded view of a preferred embodiment of the face cam clutch of the present invention.

FIG. 6 is a magnified view of the face cam of the face cam clutch of FIG. 5 showing a bottom flat surface of the face cam.

FIG. 7 is a diagram of the face cam of FIG. 6 showing a special ridge on a top portion of the face cam.

FIG. 8 is a magnified view of the cam follower of the face cam clutch of FIG. 5 showing a special ridge on a bottom portion of the cam follower.

FIG. 9 is a diagram of the cam follower of FIG. 8 showing a flat surface on a top portion of the cam follower.

FIG. 10 is a magnified bottom view of the spring-retaining piece of the face cam clutch of FIG. 5.

FIG. 11 is a side view of the spring-retaining piece of FIG. 10.

FIG. 12 is a magnified view of the drive pin of the face cam clutch of FIG.

5.

FIG. 13 is a diagram of the face cam clutch of FIG. 5 assembled.

FIG. 14 is a diagram illustrating a procedure for securing the drive pin relative to the spring-retaining piece of the face cam clutch of FIG. 5.

FIG. 15 is a diagram of a wireless phone having a hinge incorporating the face cam clutch of FIG. 5.

FIG. 16 is a magnified view of the body of the wireless phone of FIG. 15 showing the face cam clutch inserted in a portion of the hinge on the body of the wireless phone.

FIG. 17 is an exploded view of the flip of the wireless phone of FIG. 15 showing a portion of the hinge on the flip of the wireless phone.

FIG. 18 is a diagram showing the relative position of the cam clutch of FIG. 5 with respect to the flip of the wireless phone of FIG. 15.

FIG. 19 is a graph of the potential energy of the face cam clutch of FIG. 5 versus the angle between the flip and body of the wireless phone of FIG. 15 at various positions between open and closed states.

DESCRIPTION OF THE INVENTION While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility.

The following review of a conventional face cam clutch is intended to facilitate an understanding of the present invention.

FIG. 1 is an exploded view of a conventional face cam clutch 10. The face cam clutch 10 includes, from top to bottom, an additional clutch housing 12, a compression spring 14, a cam follower 16, a face cam 18, and a retaining clip 20.

The retaining clip 20 has a circular opening 22 in which a head 24 of the face cam 18 slides. The retaining clip 20 has two arms 26 having retaining protrusions 28 that latch with retaining slots 30 in the additional clutch housing 12. The compression spring 14 slides into the additional clutch housing 14 and is retained by a rear wall 32 of the additional clutch housing 12. The cam follower 16 slides into the additional clutch housing 12 adjacent to the compression spring 14. The cam follower 16 includes keys 32 that slide into key slots 34 in the additional clutch housing 12. The key slots 12 prevent the cam follower 16 from rotating within the additional clutch housing 12 but allow axial translation within the additional clutch housing 12 along a longitudinal axis 36.

The face cam 18 is retained adjacent to the cam follower 16 within the additional clutch housing 12 via the retaining clip 20. The retaining clip 20 compresses the spring 14 while retaining the face cam 18, the cam follower 16, and the spring 14 in a spring loaded state within the additional clutch housing 12. The face cam includes a tooth 38 that rides along a specially designed ridge 40 of the cam follower 16.

The face cam 18 rotates when a sufficient torque is applied to the head 24 via a tangential force applied about the longitudinal axis 36. As the face cam 18 rotates, the tooth 38 rides along the ridge 40, which compresses and decompresses the spring 14 as the cam follower 16 remains rotationally rigid within the additional clutch housing 12. Due to the design of the tooth 38 and the ridge 40, the orientation of the face cam 18 relative to the cam follower 16 is characterized by two stable states.

The stable states facilitate discreet positioning of a flip or a portable electronic device housing member (not shown) connected to a hinge (not

shown) that houses the face cam clutch 10. Unfortunately, the face cam clutch 10 is relatively expensive and bulky.

The keys 32 on the cam follower 16 and the key slots 34 in the additional clutch housing 12 must be precision machined or molded to fine tolerances, which increases the cost of the clutch 10. In addition, the requisite axial translation of the cam follower 16 within the additional housing 12 necessitates the use of very durable materials, as the keys 32 and key slots 34 are prone to excessive wear. The durable materials are often expensive and difficult to mold into thin-walled structures. Durability and material requirements of the additional clutch housing 12 necessitate the use of very thick walls, which increases the size of the additional housing 12 and the overall size of the clutch 10. The use of the additional housing 12 is especially undesirable when existing applications already have hinge housings.

A more detailed discussion of the hinge 10 of FIG. 1 is presented in U. S.

Patent No. 5,628,089, entitled RADIOTELEPHONE HAVING A SELF CONTAINED HINGE, issued May 13,1997, the teachings of which are herein incorporated by reference.

FIG. 2 is an exploded view of a face cam clutch 50 constructed in accordance with the teachings of the present invention. The face cam clutch 50 includes, from top to bottom, a retaining clip 52, a spring 54, a cam follower 56, a face cam 58, and a main drive pin 60.

The main drive pin 60 has a pin section 62 having a small horizontal slot 64 that is perpendicular to a longitudinal axis 66 of the face cam clutch 50. The main drive pin 60 also includes a disc-shaped face 70 upon which is disposed a gear 72 having a longitudinal axis that is centered with the longitudinal axis 66 of the face cam clutch 50. An opposite side of the face 70 provides a base 68 of the pin section 62 of the main drive pin 60.

The face cam 58 includes a special protrusion 92 that extends from a cylindrical body 94 of the face cam 58. The cylindrical body 94 has a cylindrical hole 74 that is concentric with the longitudinal axis 66. The diameter of the hole 74 is sufficiently large to fit the pin section 62 and the base 74 of the drive pin 60 so that the base 68 can rotate in the hole 74 of the cam follower 58. This allows

the pin section 62 to rotate freely about the longitudinal axis 66 relative to the face cam 58. The face cam 58 also includes a specially designed ridge 76, which faces opposite base 68 of the main drive pin 60. The ridge 76 is contoured to fit with a corresponding ridge 78 of the cam follower 56 when assembled, as discussed more fully below.

The cam follower ridge 78 faces toward the face cam 58 and the face cam ridge 76. The cam follower ridge 78 is positioned along a perimeter of one side of a substantially cylindrical cam follower surface 80. The cam follower 56 includes a center slot 82 that evenly divides a cam follower base 84 that is concentric with the longitudinal axis 66. The center slot 82 is shaped to fit the pin section 62 of the main drive pin 60 so that when the face cam clutch 50 is assembled, and the pin section 62 is inserted in the slot 82, the main drive pin 60 remains rotationally rigid with respect to the cam follower 56 during clutch operation. An opposite side of the substantially cylindrical cam follower surface 80 is flat and is positioned adjacent to one end of the spring 54, the other end of which rests adjacent to a base 86 of the retaining clip 52.

The retaining clip 52 has arms 88 that protrude from the base 86 of the retaining clip 52. The arms 88 include retaining protrusions 90 that face inward.

The arms are positioned and oriented with respect to the base 86 so that they fit within the center of the spring 54.

When the modular face cam clutch 50 is assembled, the retaining protrusions 90 lock into the horizontal slot 64 of the main drive pin 60 and thereby hold the spring 54, the cam follower 56, the face cam 58, and the retaining pin 60 in place and in a spring-loaded position. The center slot 82 of the cam follower 56 holds the pin section 62 of the main drive pin 60 rotationally rigid with respect to the cam follower 56. Consequently, the cam follower 56 is rotationally rigid with respect to the main drive pin 60 but can translate along the longitudinal axis 66 as the center slot 82 rides along the pin section 62 of the of the main drive pin 60.

The face cam 58 remains fixed with respect to a hinge housing wherein the face cam clutch 50 resides, as discussed more fully below, but can rotate relative to the main drive pin 60 and the cam follower 56. The base 68 of the pin

section 62 of the main drive pin 60 provides a rotational fit to the hole 74 of the face cam 58.

When a sufficient torque is applied to the gear 72 of the main drive pin 60, the main drive pin 60 rotates. To rotate the main drive pin 60, sufficient torque must be applied to cause the face cam ridge 76 to ride on the cam follower ridge 78, which compresses or decompresses the spring 54. The spring 54 decompresses as a peak of the face cam ridge 76 slides into a valley of the cam follower ridge 78. The spring 54 compresses as a peak of the face cam ridge 76 rides on a peak of the cam follower ridge 78.

In the present specific embodiment, the cam follower ridge 78 and the face cam ridge 76 have two peaks and two valleys. When a first peak of the face cam ridge 76 rests in a first valley of the cam follower ridge 78, the face cam clutch 50 is in a first potential energy state or potential energy well corresponding to a first orientation of the gear 72 with respect to the face came clutch 50. Simultaneously, a second peak of the face cam ridge 76 rests in a second valley of the cam follower ridge 78.

When a first peak of the face cam ridge 76 rests in the second valley of the cam follower ridge 78, the face cam clutch 50 is in a second potential energy state or potential energy well corresponding to a second stable orientation of the gear 72 with respect to the face cam clutch 50. The potential energies of the face cam clutch 50 in the first potential energy state and the second potential energy state are approximately equivalent.

The relative positions of the valleys and peaks on the cam follower ridge 78 and the face cam ridge 76 are 180° apart ; however, open and closed states are 150° apart as discussed more fully below. The difference, 30°, facilitates the stabilization of the first and second stable orientations, corresponding to open and closed states, respectively, of an accompanying wireless phone.

When the face cam clutch 50 is in the first or second potential energy states, the spring 54 is in a more decompressed state but remains slightly compressed to maintain a spring-loaded state of the face cam clutch 50 within an accompanying hinge housing, as discussed more fully below.

The face cam clutch 50 is in a third potential energy state when a first peak of the face cam ridge 76 rides on a first peak of the cam follower ridge 78 and a second peak of the face cam ridge 76 rides on a second peak of the cam follower ridge 78. In the third potential energy state, the gear 72 of the main drive pin 60 is in a first relatively unstable orientation relative to the face cam clutch 50.

Similarly, the face cam clutch 50 is in a fourth potential energy state when the a first peak of the face cam ridge 76 rides on a second peak of the cam follower ridge 78. The gear 72 is then in a second relatively unstable orientation relative to the face cam clutch 50.

The potential energies of the face cam clutch 50 in the third and fourth potential energy states are approximately equivalent. When the face cam clutch 50 is in the third or fourth potential energy states, the spring 54 is in a more compressed state than when the face cam clutch 50 is in the first or second potential energy states.

The face cam clutch 50 is designed for installation in a hinge housing such as a hinge housing for a wireless phone, as discussed more fully below.

The face cam 58 is slip-fit into the substantially cylindrical housing and remains fixed relative to the housing. The gear 72 of the may drive pin 60 attaches to a flip or other rotational member of the device housing. As the rotational member is manually moved, the gear 72 rotates, which rotates the cam follower 56 relative to the face cam 58 thereby locking the gear into different orientations with respect to the face cam 58 as the face cam ridge 76 rides along the cam follower ridge 78.

The protrusion 92 on the face cam 58 facilitates installation and helps to obviate the need for an additional clutch housing by holding the face cam 58 rigid with respect to the device housing. The protrusion 92 may be sized for a semi-press fit within an accompanying housing to minimize operational noise due to torque reversal when a peak of the face cam ridge 76 passes a peak of the cam follower ridge 78.

The modular design of the face cam clutch 50 provides for easy manufacture, as the various components 52,54,58, and 60 may be ordered from

an outside vendor or several outside vendors and easily slipped into and secured to a device housing.

FIG. 3 is a diagram of the face cam clutch 50 of FIG. 2 assembled. In FIG.

3, the face cam clutch 50 is in the first potential energy state, which corresponds to the first stable orientation. The main drive pin 60 connects to the retaining clip 52, which secures the spring 54, the cam follower 56, and the face cam 58 in a spring-loaded state.

FIG. 4 is an exploded view of a unique clutch hinge 100 of the present invention adapted for use with a wireless phone 102 having a flip 104 and employing the face cam clutch 50 of FIG. 2. The flip 104 includes a hinge housing 106 for housing the face cam clutch 50. The face cam clutch 50 fits within the housing 106, which latches into a slot 108 on the wireless phone 102.

The gear 72 latches into a gear hole 110 in the slot 108 and holds the gear 72 rigid relative to the wireless phone 102. As the flip 104 is opened or closed, the face cam 58 rotates with the hinge housing 106, which causes the flip 104 to lock into discreet positions relative to the wireless phone 102.

The face cam clutch 50 is designed for installation in the hinge housing 106. The protrusion 92 on the face cam 58 is slip-fit into the hinge housing 106, which secures the face cam 58 relative to the housing 106. The face cam 58 remains stationary with respect to the housing 106, which reduces wear on the rotationally-securing component 58, i. e., the cam follower 58.

In the conventional face cam clutch 10 of FIG. 1, the corresponding rotationally-securing component 16, i. e., the cam follower 16, translates, which would necessitate the use of a very durable housing and associated hinge housing 106 if the additional clutch housing 12 of FIG. 1 were omitted. The wear due to the relative movement of the cam follower 16 with respect to the housing would be exacerbated by the fact that cam follower 16 and the hinge housing 106 must be made of dissimilar materials for design reasons.

Unfortunately, sufficiently durable materials are often impractical for device housing construction. In addition, the ridges 32 of the cam follower 16 would require grooves in the hinge housing 106, which would require a thicker hinge

housing 106. Thick and bulky hinge housings result in bulky hinges that are undesirable in portable electronics applications where small size is important.

The fixed face cam 58 facilitates clutch installation, eliminates the need for very high tolerance molding or machining, and obviates the need for the additional clutch housing 12 of FIG. 1. As a result, the face cam clutch 50 is a durable, more cost-effective and space-efficient face cam clutch and results in a more cost-effective and space-efficient hinge 100 and hinge housing 106.

While the cam follower 56 axially translates as the slot 82 of the cam follower 56 slides along the pin section 62, any wear between the cam follower 56 and the hinge housing 106 will not render the face cam clutch 50 inoperable, unlike the face cam clutch 10 of FIG. 1. In addition, the effect of any wear between the cam follower 56 and the hinge housing 106 is reduced, since wear is spread over a larger area. In addition, the cam follower 56 need not remain rotationally rigid with respect to the hinge housing 106 while translating, which would otherwise increase wear between the cam follower 56 and the housing.

FIG. 5 is an exploded view of a preferred embodiment 120 of the face cam clutch of the present invention. The face cam clutch 120 includes, from top to bottom, a spring-retaining piece 122, the spring 54, an enhanced cam follower 124, an enhanced face cam 126, and an improved drive pin 128, all centered along a longitudinal axis 130.

The drive pin 128 includes a special y-shaped gear 132 having a longitudinal axis corresponding to the longitudinal axis 130 and mounted on a cylindrical base section 134, which is also concentrically positioned with respect to the longitudinal axis 130. Those skilled in the art will appreciate that the gear 132 may be another shape other than y-shaped (such as plus-shaped) without departing from the scope of the present invention. The y-shaped gear 132 is designed to facilitate plastic flow during construction via an injection molding process.

A pin section 136 is positioned on an opposite side of the cylindrical base section 134 and has a longitudinal axis coincident with the longitudinal axis 130.

The pin section 136 includes lengthwise grooves 138 which cause the pin section 136 to have a plus-shaped cross-section perpendicular to the longitudinal axis

130. A channel 140 circumscribes the pin section 136 near a top end of the pin section 136 forming a stem of a mushroom tip 118. The channel 140 is sufficiently deep to contain teeth 142 of the spring-retaining piece 122 when the face cam clutch 120 is assembled. The face cam 126 includes a cylindrical hole 144 centered about the axis 130 that is sufficiently large to allow free rotation of the pin section 136 about the longitudinal axis 130. The face cam 126 includes a special protrusion 148 for securing that face cam to a hinge housing included on a body of a wireless phone as discussed more fully below. A special ridge 150 is formed on the side of the face cam 126 opposite a bottom flat surface 146 of the face cam 126.

The cam follower 124 includes a special plus-shaped hole, as discussed more fully below, designed to grip pin section 136 of the drive pin 128 via the grooves 138, thereby holding the drive pin 128 rotationally rigid with respect to the cam follower 124.

During assembly, the face cam 126, the cam follower 124, and the spring 54 slide onto the pin section 136 of the drive pin 128. The bottom flat surface 146 of the face cam 126 rests on the base section 134 of the drive pin 128. The face cam ridge 150 faces a cam follower ridge 152. A top surface 156 of the cam follower 124 contacts a first end of the spring 54. The top surface 156 may be beveled or grooved to reduce any horizontal motion of the spring 54. A base 116 of the spring-retaining piece 122 contacts the second end of the spring 54.

The spring-retaining piece 122 latches to the drive pin 136 via the channel 140 in the drive pin 136 and the teeth 142 of the spring-retaining piece, and thereby slightly compresses the spring 54 and retains the spring 54, the cam follower 124, the face cam 126 and the drive pin 128 in an assembled position as discussed more fully below.

The face cam ridge 150 is designed to ride on the corresponding cam follower ridge 152 so that as the gear 132 of the drive pin 128 is rotated via the application of a force tangential to the longitudinal axis 130, the cam follower ridge 152 rides on the face cam ridge 150 causing the spring 54 to compress and decompress. When peaks on the face cam ridge 150 ride on corresponding peaks of the cam follower ridge 152, the spring 54 is maximally compressed and

the face cam clutch 120 is in a relatively unstable state. In this relatively unstable state, the tangential resistance about the longitudinal axis 130 at the gear 132 is relatively small. When valleys on the face cam ridge 150 ride on corresponding valleys of the cam follower ridge 152, the face cam clutch 120 is in a relatively stable state; the spring 54 is minimally compressed; and the tangential resistance about the longitudinal axis 130 at the gear 132 is relatively large.

FIG. 6 is a magnified view of the face cam 126 of the face cam clutch 120 of FIG. 5 showing the bottom flat surface 146 of the face cam 128 opposite the ridge 150. The cylindrical hole 144 is also clearly visible. The special protrusion 148 has various bevels 158 to facilitate gripping to a housing that accompanies a flip or body of a portable device.

FIG. 7 is a diagram of the face cam of FIG. 6 showing the special ridge 150 on a top portion of the face cam 126. The special ridge 150 has two valleys 160 and two peaks 162. Those skilled in the art will appreciate that a different number of valleys and peaks may be employed without departing from the scope of the present invention.

FIG. 8 is a magnified view of the cam follower 124 of the face cam clutch 120 of FIG. 5 showing the special ridge 152 on a bottom portion of the cam follower 124. In the present specific embodiment, the special ridge 152 contains two valleys 164 and two peaks 166. A plus-shape hole 168 maintains the drive pin 128 of FIG. 5 rotationally rigid with respect to the cam follower 124, but allows the cam follower 124 to translate relative to the longitudinal axis 130 of FIG. 5.

FIG. 9 is a diagram of the cam follower 124 of FIG. 8 showing the surface 156 on a top portion of the cam follower 124.

FIG. 10 is a magnified bottom view of the spring-retaining piece 122 of the face cam clutch 120 of FIG. 5. Undersides of the teeth 142 are shown. The spring-retaining piece 122 includes a centered hole 170 that fits the tip 118 of the drive pin 128 of FIG. 5 so that the teeth ride in the channel 140 of the drive pin 128. The base 116 of the spring-retaining piece 122 is beveled to help hold the spring-retaining piece 122 rigid with respect to the spring 54.

FIG. 11 is a side view of the spring-retaining piece 122 of FIG. 10 clearly showing the teeth 142 that ride in the channel 140 of the drive pin 128 of FIG. 5.

FIG. 12 is a magnified view of the drive pin 128 of the face cam clutch 120 of FIG. 5. The tip 118 has a slight under cut 178 facing the channel 140 that provides extra stability of the drive pin 128 relative to the spring-retaining piece 122 of FIG. 5.

FIG. 13 is a diagram of the face cam clutch 120 of FIG. 5 assembled. The face cam clutch 120 is shown in a stable state wherein the spring 54 is minimally compressed and holds the spring retaining piece 122 against the tip 118 and holds the cam follower 124 against the face cam 126.

FIG. 14 is a diagram illustrating a procedure for securing the drive pin 128 relative to the spring-retaining piece 122 of the face cam clutch 120 of FIG. 5.

The drive pin 128 is inserted into the spring-retaining piece 122, and a tool 172 is employed to snap the teeth 142 into the channel 140. A spring force 143 provided by the spring 54 of FIG. 13 subsequently holds the spring-retaining piece 122 against the drive pin 128. Those skilled in the art will appreciate that another installation method may be employed without departing from the scope of the present invention.

FIG. 15 is a diagram of a wireless phone 180 having a hinge 182 incorporating the face cam clutch 120 of FIG. 5. The hinge 182 provides varying degrees of tangential resistance about the longitudinal hinge axis 130, which facilitates opening and closing of a flip 184 relative to a body 186 of the wireless phone 180. The body 186 has a raised section 188, a top portion of which includes a body portion 190 of the hinge 182. A flip portion 192 of the hinge 182 is positioned on either side of the body portion 190.

FIG. 16 is a magnified view of the body 186 of the wireless phone 180 of FIG. 15 showing the face cam clutch 120 inserted in the body portion 190 of the hinge 182 of the wireless phone 180 of FIG. 15.

FIG. 17 is an exploded view of the flip 184 of the wireless phone 180 of FIG. 15 showing the flip portion 192 of the hinge 182 of the wireless phone 180 of FIG. 15. The flip portion 192 includes an idler 194 that interfaces the flip portion 192 with the body portion 190 of the hinge 182 of FIG. 15, allowing the

flip portion 192 to pivot about the longitudinal axis 130 and to move relative to the body portion 190 of the hinge 182 of FIG. 15. The construction of an idler such as the idler 194 is well known in the art.

The flip portion 192 includes a y-shaped indentation 196 positioned on the flip portion 192 opposite the idler 194 and facing inward along the longitudinal axis 130. The y-shaped indentation 196 is sufficiently deep and is shaped to secure the gear 132 of the drive pin 128 of FIG. 5 relative to the flip 184.

With reference to FIG. 16, the gear 132 of the face cam clutch 120 that is positioned on a first end of the body portion 190 fits in the y-shaped indentation 196 on a first end of the flip portion 192. The idler 194 secures a second end of the flip portion 192 to a second end of the body portion 190 and allows rotation of the flip 184 about the longitudinal axis 130.

FIG. 18 is a diagram showing the relative position of the face cam clutch 120 of FIG. 5 with respect to the flip 184 of the wireless phone 180 of FIG. 15.

For clarity, the body 186 of FIG. 15 is not shown.

FIG. 19 is a graph 200 of the potential energy of the face cam clutch 120 of FIG. 5 versus angle between the flip 184 and body 186 of the wireless phone 180 of FIG. 15 at various positions between open and closed states. The open and closed states are depicted by an open phone 202 and a closed phone 204, respectively, each having the flip 184 and the body 186. The graph 200 includes a vertical potential energy axis 206 and a horizontal flip-body angle axis 208. A potential energy curve 150'corresponds to the face cam ridge 150 of FIG. 7. The cam follower peak 166 is symbolically depicted at various positions along the potential energy curve 150'.

With reference to Figs. 7,8,15, and 19, when in the open state 202, the flip 184 is angled approximately 150° relative to the body 186. The face cam clutch 120 is in a low potential energy state 160', and the cam follower peak 166 coincides with the face cam valley 160 of FIG. 7. As the flip is 184 is closed past 90° relative to the body 186, the cam follower peak 166 passes a torque reversal point 162'. The torque reversal point 162'corresponds to a high potential energy state wherein the cam follower peak 166 of FIG. 8 coincides with the face

cam ridge 162 of FIG. 7. In the closed state 204, the flip 184 is flush against the body 186. The cam follower peak 166 is at a second potential energy state 210.

A difference 212 in potential energies between the second potentially energy state 210 and the low potential energy state 160'helps maintain the flip 184 flush against the body 186. When at the second potential energy state 210, the cam follower ridge 166 is pushed toward the next potential energy well 160'at approximately-30° by the spring 54. The cam follower ridge 166 is prevented from travelling beyond the second potential energy state 210 by a counter acting force exerted on the flip 184 by the body 186 or visa versa.

The valleys 160 and peaks 162 of the face cam 126 of FIG. 7 are separated by approximately 180°. Similarly, the cam follower peaks 166 and cam follower valleys 164 of FIG. 8 are separated by approximately 180°.

When the wireless phone 180 of FIG. 15 is in the open state 202, the cam follower peaks 166 of rest in the valleys 160 of the face cam ridge 150. If a user slightly moves the flip 184 (FIG. 15), the face cam clutch 120 of FIG. 5 and the clutch 50 of FIG. 2 will bring the flip 184 back to the open state 202. In some applications, the flip 184 may be prevented from opening past the open state 202 by a special hard stop (not shown) that is into the body 186 or the flip 184.

The open state is typically characterized by an approximately 150° angle (plus or minus a couple of degrees) between the flip 184 and the body 186.

Those skilled in the art will appreciate that the exact value of the angle is application-specific and may be easily determined by one skilled in the art to meet the needs of a given application.

As mentioned above, the torque reversal point 162'corresponds to the first unstable state wherein the peaks 162 of the face cam 126 of FIG. 7 ride on the peaks 166 of the cam follower 124. Once the flip 184 passes the torque reversal point 162', the cam follower peaks 166 advance past the face cam peaks 162 and slide toward the face cam valleys 160. However, the cam follower peaks 166 will not slide completely into the face cam valleys 160, and the centers of the peaks 166 will not directly coincide with centers of the valleys 160. This is because the wireless phone 180 is in the closed state 204 after approximately 150° of travel from the open state 202. Consequently, the phone

is held in the closed state 204, since the wireless phone 180 has an additional 30° of travel before face cam peaks 162 coincide with the cam follower valleys 164, and the face cam valleys 160 coincide with the cam follower peaks 166. The additional 30° of travel results in a force, provided by the spring 54, which pushes the cam follower peaks 166 toward the face cam valleys 160, thereby pushing the flip 184 toward the body 186. Consequently, in the closed state 204, the wireless phone 180 rests at a higher compression, resulting in a higher holding torque than in the open state 202. This helps maintain wireless phone 180 in a closed positioned.

If the flip 184 does not close fully against the body 186, a user may easily detect the imperfection, and the wireless phone 180 may not function properly.

The flip phone 180 may include a contact switch (not shown) that senses when the wireless phone 180 is closed and puts the wireless phone 180 in sleep mode, thereby extend standby time.

All parts of the face cam clutches of the present invention may be ordered, molded, or machined by one ordinarily skilled in the art.

Thus, the present invention has been described herein with reference to a particular embodiment for a particular application. Those having ordinary skill in the art and access to the present teachings will recognize additional modifications, applications, and embodiments within the scope thereof.

It is therefore intended by the appended claims to cover any and all such applications, modifications and embodiments within the scope of the present invention.

What is claimed is: