Patent ID: 8297149

Claim:
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.