Machine element or mechanism – Shaft operators – Tensioned flexible operator
Reexamination Certificate
1999-12-27
2001-11-06
Fenstermacher, David (Department: 3612)
Machine element or mechanism
Shaft operators
Tensioned flexible operator
C359S554000
Reexamination Certificate
active
06311574
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Field of the Invention
The invention concerns a device for fine positioning of a component, especially for vertical fine positioning of an objective or a revolving objective nosepiece in microscopy, with a lever system and a drive for the lever system.
The device being discussed here is, very generally, a device for fine positioning of a component. This component can be, for example, a fine-focusing stage for microscopes. Here, in particular, it is a device for vertical fine positioning of an objective or a revolving objective nosepiece, but the teaching claimed here is not limited to that specific application.
B. Description of the Prior Art
A galvanometer lifting table is already known in practice, but that has a tilting rather than a parallel lifting movement. Such a galvanometer lifting table is in any case not suitable for positioning if a parallel lift is required without a tilt error.
A fine focusing stage is known from German Patent 196 50 392 A1. In that patent, the component to be raised or lowered is designed as an object plate. Because of stiffness, the known fine focusing stage is not suitable for fine positioning of an objective or a revolving objective nosepiece. In addition to that, the known fine focusing stage is extremely limited with respect to its maximum travel.
If one wishes to finely position an objective or a revolving objective nosepiece of a microscope, parallel lifting movement is absolutely necessary because of the optical requirements. This lifting movement must be obtained with extremely accurate relative axial positioning, which should be better than 20 nm. Such accuracy is not attainable in any case for ordinary drive designs.
In many applications in microscopy, work is done directly on the object being examined. For instance, work can be done on the object by externally mounted micromanipulators during observation. Focusing of the object stage would be accompanied by undesirable relative movement between the object and the micromanipulators, and that would substantially increase the cost of the equipment. Thus it is desirable, in such applications, for the focusing to be accomplished on the objective or revolving objective nosepiece with the object stage stationary. That must be accomplished with a device of the type stated initially, with the lifting means having the desired accuracy with respect to the axial relative positioning.
SUMMARY OF THE INVENTION
This invention is based on the objective of designing and developing a device for fine positioning of a component, especially for vertical fine positioning of an objective or a revolving objective nosepiece of the type mentioned initially so that tilt-free elevation of the component being positioned is possible with simple means.
The device according to the invention for fine positioning of a component attains the above objective by the fact that a lever system acts directly on a rotating part; that the component is flexibly linked with the rotating part; and that a linkage changes the relative position of the component by rolling a flexible strip onto the rotating part, so that lifting a mount for the component produces a lifting movement of the component.
It is known, according to the invention, that a tilt-free lifting movement of the component being positioned can be attained by providing, along with the lever system and a drive for the lever system, a rotating part which is rotated immediately above the lever system. In other words, at least one lever is linked to the rotating part such that a tilting of the lever causes rotation of the rotating part. The component being positioned is, in turn, linked with the rotating part, this linkage being not rigid but flexible. The linkage between the component and the rotating part acts as a very special mount for the component, so that as the rotating part rotates, the position of the component is relatively changed by rolling of the flexible strip on the rotating part, depending on the direction of rotation. Because of this change of position between the rotating part and the component, and because of the mounting of the component, a change of the position leads to an immediate lifting movement of the component, without play and largely without friction.
Now it is fundamentally possible to achieve the features stated above by adding to an ordinary guide. Instead of an ordinary guide, the component can be mounted solely by means of the flexible linkage, so that no more extensive guiding is required.
The linkage between the rotating part and the component is very advantageously accomplished as a preferably flexible strip which is wound at least partially around the rotating part, with its free end firmly linked to the component. Finally, the strip can be springy so that it serves both as a mount for the component and also to accomplish the fine lifting or fine positioning. As the rotating part rotates, its position changes in relation to the component, so that the component is raised or lowered vertically with respect to the rotating part or to a frame or housing.
In a specific case, the strip extends like a loop around the rotating part, so that on rotation of the rotating part the position of the loop moves along the length of the strip so that the position between the loop or the rotating part and the component varies, depending on the direction of rotation of the rotating part. In one such embodiment the loop is not wound onto the rotating part. Instead, the position of the loop is changed, causing a lift of the component on realization of the arrangement specified above.
The loop in the strip being discussed here, extending around the rotating part, is produced advantageously by sticking a narrow region of the strip through a longitudinal cutout in the strip, so that the loop can be moved along the cutout by rotation of the rotating part. Slippage between the strip or the loop in the strip and the rotating part must be avoided. That can be done by fastening the strip, at least at a point, to the rotating part. Adhesion between the strip and the rotating part due to increased frictional coefficient is sufficient.
The mounting produced here can be modified by preloading the strip with a spring in any position of the component between the component and the rotating part. That provides high stability of the position of the component. The strip itself can be made of plastic or of spring steel. Spring steel is particularly useful.
To accomplish an arrangement of the parts which is tilt-free at any stage of lifting, the component is linked with the rotating part through at least two of the strips mentioned above. In that case the rotating part can be designed as a shaft extending parallel to the component. Tilt error is also avoided by placing one rotating part at each side of the component. An additional guide is not required. To that extent the component can hang properly between the rotated parts, and it has a stable position at any stage of lifting because of the preloading of the strips.
In a further advantageous manner, the component is placed within a framework or even within a housing, so that the overall height is small because of the features described above. The rotating part or parts would then extend between opposite sides of the frame or the walls. The rotating parts are mounted in bearings, in a further advantageous manner, in the frame sides or walls. Thus the rotating part could be rotated by the lever system within the frame or housing.
In one particularly advantageous embodiment, the rotating part extends through at least one of the frame sides or through at least one of the walls to the outside. If two rotating parts are provided, this measure need be applied to only one of them. The lever system is then linked to the part of the rotating part that extends out, so that the actuation is done outside the frame or housing.
To the extent that a rotating part is provided at both sides of the component, the rotation of the rotating parts must be synchronized to get exactly parallel lift. That can be acc
Engelhardt Johann
Kierschke Klaus
Fenstermacher David
Leica Microsystems Heidelberg GmbH
Simpson, Simpson & Snyder, PLLC
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