Machine element or mechanism – Mechanical movements – Reciprocating or oscillating to or from alternating rotary
Reexamination Certificate
1999-09-09
2001-07-17
Herrmann, Allan D. (Department: 3682)
Machine element or mechanism
Mechanical movements
Reciprocating or oscillating to or from alternating rotary
C016S226000, C033S568000, C108S115000, C108S116000, C108S145000, C108S147000, C248S150000
Reexamination Certificate
active
06260428
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a parallel positioner in general. More specifically to a Z-axis positioner that maintains a precise parallel relationship between two platforms while expanding or contracting in the Z-axis.
BACKGROUND ART
Previously, many types of mechanisms have been used to provide an effective means of maintaining a parallel relationship of at least one pair of fiat platforms while permitting expansion or contraction of movement in a straight line or in a Z-axis linear direction. Most prior art has utilized arms, jointed at the ends, in concert to achieve this motion. The field of robotic manipulators has been replete with this type of device, however in most cases little consideration has been given to maintain a precise relationship or parallelization on an accurate linear and tilt-free translation useful to precision equipment.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention, however the following U.S. patents are considered related:
Patent No.
Inventor
Issue Date
5,721,616
Domenicali
Feb. 24, 1998
5,237,887
Appleberry
Aug. 24, 1993
5,156,062
Appleberry
Oct. 20, 1992
4,976,582
Clavel
Dec. 11, 1990
4,806,068
Kohli et al.
Feb. 21, 1989
4,651,589
Lambert
Mar. 24, 1987
4,248,103
Halsall
Feb. 3, 1981
2,569,354
Tracy
Sep. 25, 1951
2,506,151
Hoven et al.
May 2, 1950
2,338,533
Pash
Jan. 4, 1942
2,198,635
Rossman
Apr. 30, 1938
Domenicali in U.S. Pat. No. 5,721,616 teaches a tilt-free linear micromotion translator such as an optical element, which includes a flexural suspension connected to a workpiece along a predetermined transitional axis. The flexural suspension utilizes a number of flexural links connecting points on a fixed rigid frame member. The links lie in a pair of parallel planes with the transitional axis normal to the paralleled planes. The device includes a linear motion transducer to the suspension, enabling tilt-free linear micromotion.
U.S. Pat. No. 5,237,887 issued to Appleberry discloses an apparatus which includes a static base, a platform, a first arm assembly, and a second arm assembly. The first arm assembly has a first terminal portion pivotally connected at a first pivot point to a first portion of the static base and a second terminal portion pivotally connected to the platform at a second pivot point. The first arm assembly is constructed to permit changes in the distance between the first and second pivot points, but is concomitantly constrained to movement in a desired first plane. The second arm assembly has a respective first terminal portion pivotally connected at a third pivot point to a second portion of the static base and a respective second terminal portion pivotally connected to the platform at a fourth pivot pointy. The second arm permits changes in the distance between the third and fourth pivot points but is constrained to movement in a desired second plane which is angularly disposed from the first plane. The motion of the platform is constrained to a straight line when the distance between the first and second pivot points and/or the distance between the third and fourth pivot points is changed.
U.S. Pat. No. 5,156,062 issued to Appleberry discloses an apparatus for maintaining the angular position of a platform during motion of the platform in any direction relative to a base. The apparatus includes a static base, a platform, a first arm assembly, a second arm assembly and a third arm assembly. Each arm assembly has one terminal portion connected to a portion of the static base, by a first universal joint and another terminal portion, connected to the platform, by a second universal joint. Each arm assembly is constructed to permit changes in the distance between its universal joints, but concomitantly removes a degree of angular freedom from the platform. The angular position of the platform is thereby maintained when the distance between the respective universal joints is changed.
U.S. Pat. No. 4,976,582 issued to Clavel includes a base element and a movable element along with three arms mounted with three shafts attached with linking bars forming connecting assemblies. The inclination and orientation of the moveable element remains unchanged regardless of the motion of the three control arm assemblies. The movable element supports a working element of which the rotation is controlled by a fixed motor situated on the base element.
U.S. Pat. No. 4,806,068 of Kohli et al. discloses a robotic manipulator for supporting a workpiece. The manipulator has a rotary linear actuator mounted on a base providing controlled movement of a link with two degrees of freedom. The link has one end spherically joined to a movable member which supports a workpiece. The link is articulated with the opposite end supported by a linear actuator.
Lambert in U.S. Pat. No. 4,651,589 teaches a polyarticulated mechanism having three legs situated in separated planes and formed in two parts, each associated on a spherical end and the other end to an endmost piece.
U.S. Pat. No. 4,248,103 issued to Halsall is for linkage mechanisms for industrial manipulators of the straight line conchoid type. The linkage mechanisms move in straight lines without the use of lead screws of revolute jointed arms.
For background purposes and as indicative of the art to which the invention is related reference may be made to the remaining cited patents issued to Tracy, Hoven et al., Pash and Rossman.
DISCLOSURE OF THE INVENTION
Many positioners have been developed for moving a working platform in an up and down direction or in the so called z-axis or for adjustments in precision equipment such as optics and the like. The problem is to accomplish this task with smooth movement without disproportionate hysteresis and very accurate parallelism. It is therefore the primary object of the invention to provide a positioner that overcomes all of these problems and also includes many other peripheral advantages. This is accomplished by using a flexible pivot hinge arrangement with crossed strip hinges on opposed edges of a hinge plate attached to the sides of a pair of opposed platforms. The invention, as presented, therefore requires no lubrication, and has no rolling friction or sliding of contiguous components. Further, the arrangement provides extremely long cycle life as only the axial bending of spring steel strip hinges is utilized which is not only within the normal characteristic capabilities of a material but is well within its flexural range.
An important object of the invention is the radial and axial stiffness of the positioner and its predictable and repeatable performance. The opposed platforms not only have these desirable attributes but also provide accuracy in a parallel plane with a minimum of ±5 arc seconds tilt throughout the entire travel of the device from the collapsed state where both platforms are touching to the fully extended position.
Another object of the invention is directed to its adaptability to be used in different industries since it is easy to manufacture and relatively cost effective. The primary usefulness of the positioner is for optical devices, such as reflective telescopes, where it is utilized as a compliant focuser which has a hollow arbor attached through a hole in the top platform anchoring a perforated primary mirror such as found in a cassigrain telescope. The bottom platform of the invention is mounted on a threaded backplate that interfaces with the rear of a telescope enclosure tube. The eyepiece is connected to the arbor and distends through a centrally located hole in the bottom platform. It should be noted that the platform must remain parallel throughout its entire travel in order to maintain concentricity with the mirrors, which the invention accomplishes with ease. Another application of the positioner is for testing fixtures for printed circuit boards where in-line integrated circuit packages are used for testing integrated circuits allowing continuity to be established between the traces of the substrate of chip-carrier mounted inte
Cota Albert O.
Herrmann Allan D.
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