A compliant mechanism is configured to generate a substantially constant output force in response to an input in the form of a linear displacement. The compliant mechanism is a slider mechanism whose members and their interconnects cooperate to generate a biasing force that causes the slider mechanism to generate a substantially constant output force that is substantially parallel to the linear path of a reciprocable member in response to the displacement of the reciprocable member along the linear path. To achieve the above functional characteristics, the slider mechanism is composed of structural elements, one or more of which is compliant.
The pivot-less Watt linkage supports a first rigid element relative to a second rigid element and permits relative motion between the rigid elements. The pivot-less Watt linkage comprises an elongate, rigid, floating beam, an elongate first flexible beam, an elongate second flexible beam and a flexible member. The first flexible beam extends in a first direction from a first point on the floating beam to the first rigid element. The second flexible beam extends in a second direction, substantially opposite the first direction, from a second point on the floating beam to the first rigid element. The second point is spatially separated from the first point along the length of the floating beam. The flexible member extends in the first direction from a third point on the floating beam to the second rigid element. The third point is intermediate between the first point and the second point.
A displacement modifying structure for receiving an input displacement from a motor source and generating a multiplied displacement therefrom for provision to a load. The structure includes a static beam and a dynamic beam. The static beam has a fixed end and a movable end while the dynamic beam has a first end and a second end. The first end of the dynamic beam is connected between the motive source and the movable end of the static beam. The second is also connected through a pivotless joint to the movable end of the static beam. Upon movement of the first end over a first distance by the motive source, the second end of the dynamic beam and the movable end of the static beam move over a second distance for provision to the load. The second distance, or output displacement is greater than the first distance.
Micromechanical actuation apparatus includes a substrate with an actuator mounted on the substrate and a micro-transmission mounted on the substrate coupled to the electrothermal actuator. The actuator, such as an electrothermal actuator, is responsive to electrical power to drive two output beams inwardly or outwardly in opposite directions. The micro-transmission couples the force from the two output beams and transmits the displacement of the output beams to an output node of the micro-transmission. The amplification of the micro-transmission provides a much larger displacement of a beam connected to the output node than the displacement of the output beams of the actuator.
A pivotless compliant structure is disclosed that can be used to increase the geometric advantage or mechanical advantage of a microelectromechanical (MEM) actuator such as an electrostatic comb actuator, a capacitive-plate electrostatic actuator, or a thermal actuator. The compliant structure, based on a combination of interconnected flexible beams and cross-beams formed of one or more layers of polysilicon or silicon nitride, can provide a geometric advantage of from about 5:1 to about 60:1 to multiply a 0.25-3 .mu.m displacement provided by a short-stroke actuator so that such an actuator can be used to generate a displacement stroke of about 10-34 .mu.m to operate a ratchet-driven MEM device or a microengine. The compliant structure has less play than conventional displacement-multiplying devices based on lever arms and pivoting joints, and is expected to be more reliable than such devices. The compliant structure and an associated electrostatic or thermal actuator can be formed on a common substrate (e.g. silicon) using surface micromachining.
A device for amplifying mechanical and geometrical advantage having a base structure, a first link member having a first end and a second end, and a first compliant flexural joint pivotally interconnects the first end of the first link member to the base structure. A second link member is also provided having a first end and a second end. A second compliant flexural joint pivotally interconnects the first end of the second link member to the base structure. Furthermore, a third link member is provided having a first end and a second end. A third compliant flexural joint pivotally interconnects the first end of the third link member to the second end of the first link member and a fourth compliant flexural joint pivotally interconnects the second end of the third link member to the second end of the second link member. The base structure, first link member, second link member, and third link member cooperate to define a four-bar linkage for receiving an input force and providing an amplified force or displacement output in response thereto.
