| 摘要 |
PURPOSE:To enable prevention of damage to a motor, a load and the like in case of abnormality, by detecting an increase in torque necessary for the rotation of a load shaft with a photosensor utilizing a twisting of a rotation transmitting shaft sandwiched by joint sections. CONSTITUTION:Joints 3 are so arranged as to be connectable separately to a motor shaft 1 and a load shaft 2 and a rotation transmitting shaft 6 is connected between the two joints. Light chopper blades 4 of the same shape are mounted on the shaft in the same phase. A photosensor 5 is fixed independent of the shaft 6 in such a manner to be turned ON of OFF with the blades 4. With such an arrangement, it torque necessary for the rotation of the load shaft is normal, the twisting of the shaft 6 is so slight as to obtain output signals from the sensor 5 almost completely aligned in the phase. Here, if a torque larger than the normal level is needed to rotate the load shaft, a larger shearing stress works on the shaft 5 to twist it, which causes a phase deviation in an output of the sensor 5. This deviation is detected to stop a motor thereby preventing a substantial damage to a motor or the like. |
