Gravity activated prosthetic device

Claim 2

A prosthetic device for replacing an extremity of the body comprising: a joint construction having elements capable of movement between different positions, an electrically operated drive means operatively connected to the joint construction to cause said movement, a source of electrical energy, circuit means selectively electrically connecting said source to said drive means to operate the latter, and at least one mercury switch included in the circuit means between the source and the drive means, said mercury switch being positioned such that in certain orientations of the prosthetic device the mercury switch closes the circuit means between the source and the drive means to deliver current, and in other orientations of the prosthetic device the mercury switch opens the circuit means between the source and the drive means.

Claim 3

A device according to claim 1, wherein said mercury switch is constructed such that the mercury therein crosses the terminals of the switch to close the circuit means in dependence on the rotational orientation of the switch about both (a) a reference axis passing through the switch and perpendicular to a vertical plane which includes the longitudinal axis of the device and (b) said longitudinal axis.

Claim 4

A device according to claim 2 including a pair of mercury switches connected electrically in parallel between the source and the drive means, the two switches being positioned such that movement of the device in said vertical plane about said reference axis to a first orientation closes one of said mercury switches and movement of the device in said vertical plane about said reference axis to a second orientation closes the other of said switches.

Claim 5

A device according to claim 3, said mercury switches being further constructed such that in either of said first or second orientations, a predetermined rotation of the prosthetic device about said longitudinal axis can open the circuit means.

Claim 6

A prosthetic device for replacing the lower arm and hand of the body comprising: a joint construction at the outer end of said device and capable of undergoing a grasping movement, an electrically operated drive means operatively connected to the joint construction to cause said movement, a source of electrical energy, circuit means selectively electrically connecting said source to said drive means to operate the latter, and at least one mercury switch included in the circuit means between the source and the drive means, said mercury switch being positioned such that when the device is in place as a replacement for a missing lower arm and hand, in certain orientations of the arm, the mercury switch closes the circuit means between the source and the drive means to deliver current, and in other orientations of the arm, the mercury switch opens the circuit means between the source and the drive means.

Claim 7

A prosthetic device for replacing the lower arm and hand of the body comprising: a joint construction at the outer end of said device and capable of undergoing a grasping movement, an electrically operated drive means operatively connected to the joint construction to cause said movement, a source of electrical energy, circuit means selectively electrically connecting said source to said drive means to operate the latter, and at least one mercury switch included in the circuit means between the source and the drive means, said mercury switch being positioned such that when the device is in place as a replacement for a missing lower arm and hand, in certain orientations of the arm, the mercury switch closes the circuit means between the source and the drive means to deliver current, and in other orientations of the arm, the mercury switch opens the circuit means between the source and the drive means.

Claim 8

A prosthetic device according to claim 5, wherein said mercury switch is constructed such that mercury therein crosses the terminals of the switch to close the circuit means in dependence on both (a) the vertical position of the arm and (b) the rotational position of the arm about its longitudinal axis.

Claim 9

A prosthetic device according to claim 6, including a pair of mercury switches connected electrically in parallel between the source and the drive means, a first one of said switches positioned to close when the arm is raised such that the outer end of the prosthetic device is above the shoulder, and the second of said switches positioned to close when the arm is lowered such that the outer end of the device is below the shoulder.

Claim 10

A prosthetic device according to claim 7, said mercury switches being further constructed such that rotational movement of the arm about its longitudinal axis in a predetermined direction by a predetermined amount opens both mercury switches.

Claim 11

A prosthetic device according to claim 7, wherein said first switch is an elongated capsule partially filled with mercury and extending generally parallel to said longitudinal axis with both of its terminals located near the end thereof closest to the shoulder, and wherein said second switch is a capsule partially filled with mercury with both of its terminals located near the top thereof.

Claim 12

A prosthetic device according to claim 9, wherein each capsule includes a chamber extending away from its terminals in a direction which is horizontal when the arm is in a horizontal position, both said chambers extending in the same direction from their respective terminals, such that when the arm is turned about the longitudinal axis in said direction towards which the chambers extend, mercury in both switches flows away from the respective terminals and both of said switches are opened.

Claim 13

A prosthetic device according to claim 5, wherein said mercury switch is an elongated capsule extending generally parallel to said longitudinal axis and having both terminals located near the end thereof closest to the shoulder, whereby when the arm is raised above the shoulder, mercury flows to the terminals to close the switch.

Claim 14

A prosthetic device according to claim 11, said switch including a reservoir chamber extending outwardly sideways from the elongated capsule near the terminals such that turning of the arm about its longitudinal axis toward the reservoir causes the mercury in the capsule to flow into the chamber and hence open the switch.

Claim 15

A prosthetic device according to claim 5, wherein said mercury switch is an elongated capsule extending generally perpendicular to said longitudinal axis and having the terminals located on the top thereof such that when the arm is lowered beneath the shoulder level, mercury flows to the terminals to close the switch.

Claim 16

A prosthetic device according to claim 13, wherein the cross-section of said elongated capsule is tapered downwardly, the terminals being located on the top of the switch at the part having the largest cross-section.

Claim 17

A prosthetic device according to claim 5, said mercury switch including baffles located therein to limit the flow of mercury therein.

Claim 18

A prosthetic device according to claim 5, said joint construction having grasping parts to perform such grasping movement, and including a spring normally urging the grasping parts of the joint construction apart, and including a slip clutch connected between the drive means and the joint construction such that operation of the drive means in one direction causes the grasping parts to perform the grasping movement, said clutch slipping when the drive means force exceeds a predetermined limit, and wherein upon release of the driving force, the spring causes the grasping parts to separate.

Claim 19

A prosthetic device according to claim 16, wherein the outer extremity of the device is in the shape of a hand, said grasping parts including the thumb and forefinger of the hand, and said spring being arranged to normally urge the thumb and forefinger apart.

Claim 20

A prosthetic device according to claim 17, said drive means being an electric motor having an output shaft, a further shaft drivingly engaging the forefinger, and urging it towards the thumb, the slip clutch being located between the motor shaft and the further shaft, a cross-shaft extending generally perpendicular to the longitudinal axis, and the forefinger part of the hand being fixed to the cross-shaft for movement therewith in said grasping movement.

Claim 21

A prosthetic device according to claim 17, wherein at least one finger other than the forefinger of the hand is a grasping part and is movable under the influence of said drive means towards the thumb during said grasping movement.

Claim 22

A prosthetic device according to claim 5, including a manually operated switch located externally of the arm for completely disenabling the said drive means.