Article comprising a Z-axis positioning stage

Details Article comprising a Z-axis positioning stage Article comprising a Z-axis positioning stage

1999-03-19

2001-03-20

Look, Edward K. (Department: 3745)

Expansible chamber devices

With support or frame

Reexamination Certificate

active

06202539

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a positioning stage. More particularly, the present invention relates to stage that is positionable along the z-axis.
BACKGROUND OF THE INVENTION
The need for precision positioning arises in a wide variety of arts, and many different devices have been devised to satisfy that need. Such devices are generically referred to as positioning stages.
Positioning stages are typically operable to move along one or two or three or more axes. Horizontal one- or two-axes positioning stages are relatively easy to implement, although the art is replete with relatively complicated implementations of such X-Y stages that include elements such as position sensors and linear motors as drive devices.
Vertical (Z-axis) positioning stages are more difficult to implement than horizontal (X-Y) positioning stages. Unlike X-, Y- or XY-stages, a Z-axis positioning stage is not supported in the horizontal plane and therefore requires stabilization in that plane, as well as along the Z-axis. Typically, rails, guide pins, scissors systems or the like are required to maintain the X-Y position of a vertical positioning stage. Moreover, for Z-axis positioning, the weight of the stage and frictional forces associated with the stage's movement must be overcome.
Z-axis positioning stages become especially complicated when rapid stage movement is required. The art has addressed such complications with electrically-driven systems incorporating ball screws, belts and the like, as well as with pneumatically-driven systems. Electrically-driven systems are very complex and require numerous components, and pneumatically-driven systems tend to be very bulky. Both electrical and pneumatic systems typically require special structural frames and supports. Due to their complexity, such systems are relatively expensive and may suffer from reliability problems.
The art would therefore benefit from a simple z-axis positioning stage capable of rapid, precise positioning. Such a stage would be more reliable and less expensive than conventional z-axis positioning stages.
SUMMARY OF THE INVENTION
In one embodiment, a Z-axis positioning stage in accordance with the present teachings includes at least one collapsible/expandable cell or cavity that is defined between a lower and an upper surface and a side wall depending therefrom. A device that is operable to collapse/expand the cavity is operatively connected to the cavity.
During collapse of the cavity, the upper surface drops towards the lower surface. During expansion of the cavity, the upper surface rises away from lower surface. The upper surface thus functions as a movable stage, which is capable of moving an object placed thereon in a vertical direction (i.e., along the z-axis).
In some embodiments, cavity collapse/expansion is effected by changing pressure within the cavity. This can be accomplished via vacuum-generating equipment or pressurizing equipment. In additional embodiments, feedback control is advantageously incorporated in the Z-axis positioning stage. An illustrative feedback system includes a displacement sensor, a controller, and a final control element.
In further embodiments, the present invention comprises a two-, three- or more axes positioning stage. In such embodiments, the present Z-axis positioning stage is advantageously used in conjunction with horizontal (X-, Y- or XY) positioning stages.
Conventional Z-axis positioning stages typically use rigid drive systems. If a dispensing member (e.g., a syringe) malfunctions and forceably contacts a receiver vessel disposed on such a rigidly-driven stage, the dispensing member is likely to be damaged. The present Z-axis stage advantageously possesses a “pliability” or “springiness” by virtue of its “cavity drive” that reduces the likelihood of damage under the aforementioned scenario.


REFERENCES:
patent: 2576908 (1951-11-01), Wallace
patent: 2668517 (1954-02-01), Craft
patent: 3420147 (1969-01-01), Beach
patent: 3469502 (1969-09-01), Gardner
patent: 5181452 (1993-01-01), Immega
patent: 5317952 (1994-06-01), Immega
patent: 5697285 (1997-12-01), Nappi et al.
patent: 5702083 (1997-12-01), Lai

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