US 7,567,012 B2Granted

Drive unit

AssigneeKonica Minolta Opto, Inc.

InventorTaketo Namikawa

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Abstract

A drive unit being characterized in that a movable object can be prevented from being tilted when the movable object is stopped using a restricting member. The drive unit comprises a piezoelectric element, a rod provided at an end of the piezoelectric element, a movable object frictionally engaged with the rod, and drive pulse generating means that apply drive signals to the piezoelectric element. The drive pulse generating means apply to the piezoelectric element a rectangular wave drive signal that has a duty ratio other than 0.5 and vibrates the rod so that a difference occurs between the expansion and contraction of the rod when the movable object is moved, and apply to the piezoelectric element a rectangular wave drive signal that has a duty ratio of 0.5 and vibrates the rod so that the movable object is not moved substantially when it is detected that the movable object is in contact with a restricting member.

Claims15

Dependent claims

A drive unit comprising:

an electromechanical transducer capable of expanding/contracting by drive signal application,
a supporting member that is connected to said electromechanical transducer and displaced together with said electromechanical transducer,
a movable object that is slidably supported on said supporting member and moves along said supporting member owing to a vibration of said supporting member by virtue of the expansion/contraction of said electromechanical transducer,
a restricting member that restricts a movable range of said movable object,
a drive circuit that applies to the electromechanical transducer a first wave drive signal for vibrating said supporting member so that a difference occurs between the expansion and contraction of said electromechanical transducer when said movable object is moved to a position where said movable object makes contact with said restricting member, and applies to the electromechanical transducer a second wave drive signal for vibrating said supporting member so that said movable object is not moved substantially after said movable object makes contact with said restricting member.

2 more elements

Dependencies are inferred from the claim text.