Torque meter

Claim 1

APPARATUS FOR PROVIDING AN ELECTRICAL SIGNAL HAVING A MAGNITUDE WHICH VARIES IN ACCORDANCE WITH THE MAGNITUDE OF THE TORQUE APPLIED TO A ROTATABLE SHAFT COMPRISING ILLUMINATION MEANS ANNULARLY DISPOSED ABOUT THE SHAFT FOR PROVIDING ANNULARLY A SUBSTANTIALLY CONSTANT INTENSITY OF ILLUMINATION, A FIRST AND SECOND PHOTORESPONSIVE MEMBER BEING ANNULARLY DISPOSED ABOUT THE SHAFT FOR PROVIDING AN ELECTRICAL CHARACTERISTIC VARYING IN ACCORDANCE WITH THE QUANTITY OF LIGHT RECEIVED FROM SAID ILLUMINATION MEANS, FIRST INTERFERENCE MEANS BEING LOCATED BETWEEN SAID ILLUMINATION MEANS AND SAID PHOTORESPONSIVE MEMBERS AND HAVING A PLURALITY OF LIGHT TRANSMITTING AND LIGHT REJECTING AREAS ANNULARLY DISPOSED IN REGULAR INTERVALS ABOUT THE SHAFT AND HAVING A LIGHT TRANSMITTING PORTION ANNULARLY DISPOSED ABOUT THE SHAFT, SECOND INTERFERENCE MEANS HAVING A PLURALITY OF LIGHT TRANSMITTING AND LIGHT REJECTING AREAS ANNULARLY DISPOSED IN REGULAR INTERVALS ABOUT THE SHAFT IN JUXTAPOSITION TO SAID AREAS OF SAID FIRST INTERFERENCE MEANS AND BEING OPERATIVELY ASSOCIATED WITH SAID FIRST INTERFERENCE MEANS FOR MODULATING THE QUANTITY OF LIGHT TRANSMITTED BY SAID ILLUMINATION MEANS TO SAID FIRST PHOTORESPONSIVE MEMBER IN ACCORDANCE WITH THE RELATIVE ROTATION BETWEEN SAID AREAS ON SAID FIRST AND SECOND INTERFERENCE MEANS AND HAVING A LIGHT TRANSMITTING PORTION IN JUXTAPOSITION TO SAID PORTION ON SAID FIRST INTERFERENCE MEANS FOR PROVIDING FOR THE TRANSMISSION OF A SUBSTANTIALLY CONSTANT QUANTITY OF LIGHT FROM SAID ILLUMINATION MEANS TO SAID SECOND PHOTORESPONSIVE MEMBER, SAID FIRST AND SAID SECOND INTERFERENCE MEANS BEING SECURED TO THE SHAFT AT AXIALLY SPACED LOCATIONS WITH THE RESULT THAT SUCH MEANS ARE ROTATIONALLY DISPLACED WITH RESPECT TO ONE ANOTHER IN PROPORTION TO THE TWISTING UNDER LOAD OF THE SHAFT PORTION BETWEEN THE LOCATIONS OF CONNECTION OF SUCH MEANS TO THE SHAFT.