Capacitive torque sensor and method of detecting torque

A non-contact capacitive torque sensor comprising:

• a bar having a circular cross-section,
• a dielectric layer which is formed on at least a part of an outer peripheral surface of said bar and which is variable in dielectric constant in accordance with a strain applied to said dielectric layer,
• a pair of interdigital electrodes facing said dielectric layer and forming a single capacitor,
• a first coil provided along the outer peripheral surface of said bar and forming one inductor,
• a connecting part connecting said capacitor and said inductor with each other to form a closed circuit, and
• a second coil electromagnetically coupled to said first coil with a small gap left therebetween,
• wherein said interdigital electrodes comprise a plurality of linear electrodes inclined at a predetermined acute inclination angle with respect to a center axis of said bar,
• wherein said linear electrodes are directly formed on a surface of said dielectric layer, and
• wherein said bar has a magnetic portion formed on at least a part thereof in a direction along the center axis of said bar, and said first coil is provided in said magnetic portion.

A non-contact capacitive torque sensor comprising:

• a bar having a circular cross-section,
• a dielectric layer which is formed on at least a part of an outer peripheral surface of said bar and which is variable in dielectric constant in accordance with a strain applied to said dielectric layer, and
• a pair of interdigital electrodes facing said dielectric layer and forming a single capacitor, and
• a cylindrical insulator fitted to said bar and facing said dielectric layer with a small gap left therebetween,
• wherein said interdigital electrodes comprise a plurality of linear electrodes inclined at a predetermined acute inclination angle with respect to a center axis of said bar, and
• wherein said linear electrodes are formed on a peripheral surface of said cylindrical insulator.