Patent Description:
In various mechanical systems such as an optical system having a microscope, fixing one component to another component may have to be rigid. However, such a rigid fixing cannot be sufficiently achieved for many reasons. For example, in some applications, position of a component may need to be changed frequently and rapidly. In traditional fixing mechanisms, it is not convenient to repeatedly fixing and releasing a component that requires changing its position frequently and rapidly during operation or setup.

Therefore, there is a need for mechanical systems so that components can be more rigidly fixed to each other as well as allowing frequent quick fix-release operations. <CIT> discloses a clamping device configured to release a clamping force or a braking force acting on a rotating shaft such as a motor output shaft by using a multilayer. piezoelectric element. The multilayer piezoelectric element is assembled to the annular part so that the diameter of the annular part expands and contracts with expansion and contraction of the multilayer piezoelectric element. The invention is set out in the independent claim <NUM>. Further developments are recited in the dependent claims.

An embodiment of the present invention provides a braking device including:
a piezoelectric element; and a braking portion configured to fix to a member when the piezoelectric element is in a first state, and to release the member when the piezoelectric element is in a second state. The piezoelectric element changes from the first state to the second state when a voltage is applied to the piezoelectric element.

In one embodiment, the braking portion of the braking device is configured to surround the member to clamp the member. A force element may be used to provide the clamping force.

In one embodiment, the braking portion includes two ends facing to each other, and the braking portion is provided with a gap that is located between the two ends, and a distance between the two ends of the braking portion varies while the piezoelectric element changes from one state to another state. A clearance between the braking portion and the member may be adjustable. When the cross-section of the member is a circle, and the braking device also fixes the member from rotating.

In one embodiment, the braking device may be used for mounting and releasing of optical element from an optical post. For example, the braking device may be attached to a post holder or an optical mount, so that the position and angle of an optical element may be adjusted when the braking device releases the pole and then locked in place when the braking device fixes post.

In one embodiment, the braking device may be used in a gimbal having multiple pivots in which the braking device fixes and releases one or more of the multiple pivot pins.

An embodiment of the present invention provides a positioning system including at least one strut assembly that includes a braking device including a piezoelectric element; and a braking portion configured to fix to a member when the piezoelectric element is in a first state, and to release the member when the piezoelectric element is in a second state.

Some examples of the above embodiment may include: a hexapod having six strut assemblies with one or more of the braking devices, a tripod having three strut assemblies with one or more of the braking devices, or a monopod having one strut assembly with one braking device.

An embodiment of the present invention provides a linear drive including a first and second piezoelectric braking devices; a body connecting the two braking devices at two ends along a length of the body; and a processor configured to control the first and second braking devices and to change the length of the body between a first length and a second length, such that when the first braking device fixes to a member, then the second braking device releases the member and the length of the body is at the first length; and when the first braking device releases the member, then the second braking device fixes to the member and the length of the body is at the second length.

Relative terms such as "lower," "upper," "horizontal," "vertical," "above," "below," "up," "down," "top" and "bottom" as well as derivative thereof (e.g., "horizontally," "downwardly," "upwardly," etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion.

This disclosure describes the best mode or modes of practicing the invention as presently contemplated. This description is not intended to be understood in a limiting sense, but provides an example of the invention presented solely for illustrative purposes by reference to the accompanying drawings to advise one of ordinary skill in the art of the advantages and construction of the invention. In the various views of the drawings, like reference characters designate like or similar parts.

A braking device according to an embodiment is shown in <FIG> illustrates a cross-sectional view of a structure according to one embodiment of the present invention. <FIG> illustrates a side view of a structure according to one embodiment of the present disclosure.

The structure <NUM> shown in <FIG> may include a member <NUM>, a supporter <NUM>, and a braking device <NUM>. The member <NUM> may include a longitudinal axis Ox. The member <NUM> may extends in a longitudinal axis direction Z. The member <NUM> may include a circular cross-section. The member <NUM> may be made of any kind of material, such as metal, plastic, and composite material. Note that the cross-section of the member <NUM> is not limited to a circle, any geometrical shape is possible as long as the braking device <NUM> is configured to grip one or more surfaces of the bar member. The supporter <NUM> may support the bar member <NUM> slidably in the longitudinal axis direction Z of the member <NUM>. The supporter <NUM> may surrounds a part of the member <NUM>. In one embodiment, the supporter <NUM> may include a hole that may have a circular cross-section that may accommodate a part of the member <NUM>. Supporter <NUM> may be made of any kind of material, such as metal, plastic, and composite material.

The braking device <NUM> may be fixed to the supporter <NUM>. The braking device <NUM> may be configured to brake the member <NUM>. In one embodiment, the braking device <NUM> may be slidable along the member <NUM>. The braking device <NUM> may be made of any kind of material, such as metal, plastic, and composite material. The braking device <NUM> may include a braking portion <NUM>, a piezoelectric element <NUM>, and a forcing element <NUM>.

The braking portion <NUM> may be configured to fix to and be slidable along the member <NUM>. The braking portion <NUM> may be fixed to the member <NUM> by clamping the member <NUM>. The braking portion <NUM> may surrounds the member <NUM>. In the illustrated example, the braking portion <NUM> may include a split ring <NUM> and parts <NUM> and <NUM>. The split ring <NUM> may surround the member <NUM> to clamp the member <NUM>. The split ring <NUM> of the braking portion <NUM> may include two ends 131A and 131B. The two ends 131A and 131B may face to each other. The braking portion <NUM> may be provided with a gap <NUM> that is located between two ends 131A and 131B. The part <NUM> may be connected to the split ring <NUM> at a side of the end 131A. The part <NUM> may be connected to the split ring <NUM> at a side of the end 131B. The part <NUM> may be spaced apart from the part <NUM>.

The piezoelectric element <NUM> may be engaged with the braking portion <NUM>. In the example shown in <FIG>, the piezoelectric element <NUM> may be disposed in the braking portion <NUM>. Specifically, in <FIG>, the piezoelectric element <NUM> may be disposed in a space formed by the parts <NUM> and <NUM> of the braking portion <NUM>. The piezoelectric element <NUM> may be disposed along a direction perpendicular to the longitudinal axis direction Z of the member <NUM>. In <FIG>, the piezoelectric element <NUM> is disposed along a direction in which the two ends 131A and 131B are spaced apart from each other. In the illustrated example, the piezoelectric element <NUM> may include a linear shape.

The piezoelectric element <NUM> may be in a first state and a second state. When the piezoelectric element <NUM> is in the first state, the braking portion <NUM> may be fixed to the member <NUM>. When the piezoelectric element <NUM> is in the second state, the braking portion <NUM> may not be fixed to the member <NUM>, and may be slidable along the member <NUM>. The member <NUM> may be adjusted to the supporter <NUM> in the longitudinal direction Z when the braking portion <NUM> does not fixed to the member <NUM>. The state of the piezoelectric element <NUM> may change from one state to another state when a voltage is applied to the piezoelectric element. For example, the piezoelectric element <NUM> may expand in a longitudinal direction of the piezoelectric element <NUM> when a voltage is applied to the piezoelectric element <NUM>. In this example, the first state of the piezoelectric element <NUM> may be an expanded state, and the second state of the piezoelectric element <NUM> may be a non-expanded state. Alternatively, the piezoelectric element <NUM> may contract in the longitudinal direction of the piezoelectric element <NUM> when a voltage is applied to the piezoelectric element <NUM>. In this example, the first state of the piezoelectric element <NUM> may be a contracted state, and the second state of the piezoelectric element <NUM> may be a non-contracted state.

In the illustrated example shown in <FIG>, a distance D1 between the two ends 131A and 131B of the braking portion <NUM> may vary while the piezoelectric element <NUM> expands or contracts.

As shown in <FIG>, the structure <NUM> may further include a forcing element <NUM>. The forcing element <NUM> may provide the braking portion <NUM> with a force by which the braking portion <NUM> clamps the member <NUM>. Examples of the forcing element <NUM> include a screw, combination of a bolt and a nut, and a spring. In the example of <FIG>, the forcing element <NUM> may fix one of the parts <NUM> and <NUM> of the braking portion <NUM> to the other one of the parts <NUM> and <NUM> of the braking portion <NUM>.

In another embodiment, as shown in <FIG>, the piezoelectric element <NUM> may be disposed along a direction perpendicular to the direction in which the two ends 131A and 131B are spaced apart from each other. In the example of <FIG>, the piezoelectric element <NUM> may include a wedge-shaped tip and the wedge-shaped tip of the piezoelectric element <NUM> may push the two ends 131A and 131B to expand the distance D1 when the piezoelectric element <NUM> changes. As such, the distance D1 between the two ends 131A and 131B of the braking portion <NUM> may vary while the piezoelectric element <NUM> expands or contracts.

In the embodiments shown in <FIG> as well as <FIG>, the member <NUM> can be rigidly fixed to the supporter <NUM> when the braking portion <NUM> of the braking device <NUM> is fixed to the member <NUM>. This can enhance reliability of fixing of the member <NUM> to the supporter <NUM>. In particular, the braking device <NUM> may lock rotational and longitudinal movements of the member <NUM> to the braking portion <NUM>. In addition, the first and second states of the piezoelectric element <NUM> may be switched at a higher speed by switching application of a voltage to the piezoelectric element <NUM>. Further, the braking device <NUM> is configured to adjust a tolerance between the braking portion <NUM> and the member <NUM>.

The braking device discussed in view of <FIG> may be applied to various systems. One example of the application of the breaking device includes a adjustable stage for an optical element. In one embodiment, the stage is a hexapod. This allows for a virtual pivot point at which the platform may be rotated about. In other embodiments, the stage may include three strut assemblies arranged as a tripod configuration to provide three degrees of freedom movement of a platform, or include one strut assembly arranged as a monopod configuration to provide one degree of freedom movement of a platform. In these embodiments, one or more of the braking devices are mounted to the strut assembly and configured to brake a shaft from extending, retracting, or rotation.

<FIG> illustrates a non-limiting example that a microscope is mounted on an adjustable stage, so that the position and orientation of the entire microscope can be adjusted.

<FIG> is a perspective view of a stage that includes six strut assemblies arranged as a hexapod configuration according to an embodiment.

<FIG> shows a strut assembly according to an embodiment. A shaft in the strut assembly may extend or retract. In one embodiment, the strut assembly includes an actuator to control the extension and retraction of the shaft. In another embodiment, the shaft freely extends and retracts without an actuator.

The member <NUM> in <FIG> may be the shaft <NUM> in <FIG>. The supporter <NUM> in <FIG> may be the housing <NUM>. In addition, the braking device <NUM> in <FIG> may be located at the end of the housing through which the shaft extends or retracts. In addition, the flexure assembly may be locked when the piezoelectric element <NUM> is in the first state, and may be unlocked from the shaft <NUM> when the piezoelectric element in the second state. In another example, the member <NUM> in <FIG> may be an air cylinder of the strut assembly. In one example, the strut assembly may include two braking devices <NUM>, and the two braking devices <NUM> may alternately perform locking and unlocking functions.

In the embodiments shown in <FIG>, each strut assembly may be locked when the piezoelectric element <NUM> is in the first state, and each strut assembly may be unlocked to be adjusted when the piezoelectric element <NUM> is in the second state.

In the present embodiments, the shaft <NUM> can be rigidly fixed to the housing <NUM> for the same reasons discussed above in view of <FIG>. This can enhance reliability of fixing of the shaft <NUM> to the housing <NUM>. In addition, as discussed above, the first and second states of the piezoelectric element may be switched at a higher speed by switching application of a voltage to the piezoelectric element. Therefore, the position of the shaft <NUM> relative to the housing <NUM> can be conveniently adjusted.

Furthermore, the braking portion may be precisely honed to the shaft <NUM> to create a very tight tolerance between the shaft <NUM> and the braking portion, so that the piezoelectric element <NUM> may need only to expand or contract about <NUM>-<NUM> microns to lock or unlock the brake.

Further, the platform of the apparatus may be a gimbal platform. When the bar member and/or pivot pins of the gimbal apparatus are not clamped by the braking device <NUM>, the stage of the apparatus of <FIG> may become in a stable posture by gravitation. Then, the bar member and/or the pivot pins may be clamped by the braking device <NUM>. This means that the stage of the apparatus may move like a gimbal apparatus. In such a case, the stage of the apparatus can be adjusted without an actuator in a strut assembly, and a user may adjust the stage by unlocking the brakes and adjusting the stage to a desired position and then locking the stage in place.

Further, in one embodiment, multiple braking devices may be used together in a system, in which individual braking devices are controlled to fix or release a member according to a programmable sequence. For example, in a system including a first and second braking devices, and a processor is configured to control the first and second braking devices, such that: when the first braking device is in the first state, the second braking device is in the second state; and when the first braking device is in the second state, the second braking device is in the first state. In the application of a linear drive, the first and second braking devices are connected by a bar that can expand and contract. A processor may control the states of the two braking devices and the bar in a sequence such that when the first braking device fixes to a member, then the second braking device releases the member and the length of the body is at the first length; and when the first braking device releases the member, then the second braking device fixes to the member and the length of the body is at the second length. Such sequence of actions would cause the drive to travel along the member.

It is contemplated that one or more of the braking devices may be used in conjunction with or without other components in a number of systems that may require tight tolerances between moving parts with rapid and controllable braking actions.

<FIG> and <FIG> illustrate views of a braking structure according to another embodiment of the present invention. In <FIG> and <FIG>, a piezoelectric element 133a may expand along the axis of a shaft <NUM>. In one embodiment, the braking structure shown in <FIG> and <FIG> may include at least one flexure <NUM> (for example, two flexures <NUM> in <FIG> and <FIG>) between portions <NUM> and <NUM>. In another embodiment, the portions <NUM> and <NUM> are connected via a hinge or equivalent moveable linking means. In the illustrated example, when the piezoelectric element 133a expands, the portions <NUM> of the structure may move relative to <NUM> via the flexures <NUM> to twist and bind against the shaft <NUM> to effect the braking.

Claim 1:
A braking device (<NUM>) including:
a piezoelectric element (<NUM>); and
a braking portion (<NUM>) configured to surround a member (<NUM>) and to clamp the member when the piezoelectric element (<NUM>) is in a first state, and to release the member (<NUM>) when the piezoelectric element (<NUM>) is in a second state, wherein the piezoelectric element changes from the first state to the second state when a voltage is applied to the piezoelectric element;
and characterized in that the braking portion (<NUM>) comprises a split ring (<NUM>) that is split at a location on the ring such that a gap (<NUM>) is formed between a first split end (131A) of the ring and a second split end (131B) of the ring, with the first and second split ends facing each other, and
wherein the braking device (<NUM>) comprises further a first part (<NUM>) extending from the first split end (131A) away from the member (<NUM>) and a second part (<NUM>) extending from the second split end (131B) away from the member (<NUM>) and the piezoelectric element (<NUM>) is placed between a space formed by the first and second parts (<NUM>, <NUM>) such that a distance (D1) of the gap (<NUM>) between the facing surfaces of the first and second split ends (131A, 131B) varies while the piezoelectric element (<NUM>) changes between the first state and second state.