Friction drive actuator

A friction drive actuator for driving a sliding member in a predetermined direction, comprising:

• at least one vibration member which is configured to be driven to vibrate by expansion and contraction of a piezoelectric displacement portion which is included in the vibration member and driven by a driving signal;
• a pressing member which causes the vibration member and the sliding member to come into a pressure contact therebetween;
• and
• a control member which is provided on each of the vibration member and the sliding member at a contact portion therebetween and which is configured to set the sliding member in a unique position with respect to the vibration member in a direction other than the predetermined direction when the vibration member and the sliding member are pressedly contacted with each other by the pressing member,
• wherein the sliding member is in contact with the vibration member and is driven by the vibration member in the predetermined direction with respect to the vibration member,
• wherein the control member disposed on the sliding member includes:
• a groove portion having a v-shaped elongated groove which is formed along the predetermined direction and has a V-shaped cross section perpendicular to the predetermined direction;
• and
• a flat strip portion provided parallel to the v-shaped elongated groove,
• wherein the control member disposed on the vibration member includes:
• two first projections which are provided in the predetermined direction with an interval therebetween and are in contact with inner walls of the v-shaped elongated groove;
• and
• a second projection which is provided between the first projections and is in contact with the flat strip portion.