Ultrasonic motor

1. An ultrasonic motor, comprising:

a stator that includes a comb body with a plurality of circumferentially-arranged comb-like projections and a piezoelectric body integrally mounted on the comb body;

a rotor rotatable with respect to the stator, the rotor having a contact surface that establishes pressure contact with the stator; and

a resin film formed with predetermined hardness on the contact surface of the rotor, the resin film containing a solid lubricant,

wherein the resin film comprises one of:

a resin film comprising a phenol epoxy resin, and a polytetrafluroethylene (PTFE) or fluorinated ethylene-propylene (FEP) solid lubricant, and having a pencil hardness of “B”;

a resin film comprising a polyamide-imide resin, and a PTFE or graphite solid lubricant, and having a pencil hardness of at least “F”; and

a resin film comprising a polyamide-imide resin and a PTFE or molybdenum disulfide (MoS 2 ) solid lubricant, and having a pencil hardness of at least “F”.

2. The ultrasonic motor according to claim 1 , wherein the solid lubricant comprises a mixture of at least two of PTFE, perfluoroalkoxy polymer resin (PFA), and FEP.

3. The ultrasonic motor according to claim 1 , wherein the resin film is formed by being applied onto the contact surface of the rotor.

4. The ultrasonic motor according to claim 1 , wherein the resin film is formed with a thickness of 1 micrometer to 100 micrometers.

5. The ultrasonic motor according to claim 4 , wherein the resin film is formed with a thickness of 30 micrometers to 40 micrometers.

6. The ultrasonic motor according to claim 1 , wherein the contact surface of the rotor is formed in an annular shape with a radial width smaller than that of the comb body.

7. The ultrasonic motor according to claim 1 , wherein the rotor and stator are formed from metal material.