Bistable hinge mechanism

A hinge adapted to pivotably connect a hinged member to a device housing and being adapted to maintain the hinged member in one of an open position and a closed position relative to the device housing, the hinge comprising:

• a first hinge part having an axis and a cam follower, the first hinge part being adapted to be connected to one of the hinged member and the device housing;
• a second hinge part aligned with and rotatable about the axis of the first hinge part, the second hinge part having a non-planar cam surface, the cam follower on the first hinge part contacting the cam surface in non-planar mating engagement for movement of the cam follower axially with respect to the cam surface, the cam surface having a first axial position and a second axial position, the second hinge part being adapted to be connected to the other of the hinged member and the device housing;
• a spring which urges the cam follower against the cam surface with a spring force;
• an axial load bearing connector which connects the first and second hinge parts in which spring force is reacted, the connector having first and second ends to secure the first and second hinge parts and spring therebetween, wherein the hinge is adapted to hold the hinged member in an open position relative to the device housing when the cam follower is engaging the first axial position of the cam surface;
• and
• a torque element located between the first and second hinge parts, the torque element having a higher friction torque in a first rotational direction of the first hinge part relative to the second hinge part than in a second rotational direction of the first hinge part relative to the second hinge part which is adapted to maintain the hinged member in a stable state in the first position.

A method of assembling a hinged member to a device housing, comprising:

• (a) providing a preassembled hinge which includes a first hinge part with a first outer shape and a second hinge part with a second outer shape;
• (b) providing one of a hinged member and a device housing with a first bore located along a hinge axis, the first bore being complementary to and engagable by the first outer shape of the first hinge part;
• (c) providing the other of the hinged member and the device housing with a second bore located along the hinge axis which is complementary to and engagable by the second outer shape of the second hinge part, the second bore being of sufficient size to allow the first hinge part to pass therethrough;
• (d) aligning the hinged member and the device housing such that the first and second bores are axially aligned;
• (e) inserting the first hinge part through the second bore and into the first bore inwardly from outside the device housing such that the first outer shape of the first hinge part engages in the first bore and the second outer shape of the second hinge part engages in the second bore.

A method of assembling a hinge, comprising:

• (a) providing a pin having first and second ends, the first end including a head and the second end having a first diameter;
• (b) placing a first hinge part having an axial bore defined therethrough on the pin, the first hinge part including a cam follower;
• (c) placing a second hinge part having a second axial bore defined therethrough on the pin, the second hinge part rotatable about an axis of the first hinge part, the second hinge part having a cam surface, the cam follower on the first hinge part contacting the cam surface, the second hinge part including a counter bore of a second diameter aligned with the axial bore on an opposite side from the cam surface such that the second end of the pin extends into the counter bore;
• and
• (d) pressing a bushing simultaneously onto the second end of the pin and into the counter bore, the bushing having an inside diameter which is smaller than the first diameter, and an outer diameter which is smaller than the second diameter, the bushing expanding as it is pressed onto the pin creating an interference fit between the second diameter and the bushing.