High precision gas bearing split-axis stage for transport and constraint of large flat flexible media during processing
View Patent ↗A modular split-axis stage is used to inspect and/or repair large flat glass media suitable for LCD/TFT applications. Low-precision air table sections are detachably mounted to a centrally located, high-precision granite inspection/repair section. Glass media held by a vacuum contact is transported on air cushions from the up-web air table to the central inspection/repair section. Vacuum nozzles integrated with porous medium pads precisely control the height of the flexible media above the central section during inspection or repair. Embodiments includes structures in which the media is either stationary or moving during inspection/repair. A first media can be loaded/unloaded while a second media is undergoing inspection or repair in a pipelined operational mode.
1. A split-axis stage in a flat panel inspection system suitable for inspection of large, substantially planar, thin, flexible media, the media comprising elements of TFT LCD arrays, the stage comprising:
a first section operative to position the media with a first handling precision and to transport the media in a first direction;
a second section physically coupled to the first section, the second section operative to receive the media from the first section, to position the media with a second handling precision, and to transport the media further in the first direction, only the second section including a stable and rigid support structure such that the second handling precision is more precise than the first handling precision; and
instrumentation mounted to the second section, the instrumentation being operative to characterize physical attributes of elements of the media received by the second section from the first section.
2. The inspection system stage according to claim 1 wherein the first section is modular and the second section is modular and removably connectable to the first section, and wherein the support structure of the second section comprises a granite slab.
3. The inspection system stage according to claim 2 wherein the handling precision of the second section is enhanced by the stability of the granite slab to be sufficient to controllably position the media within a final tolerance.
4. The inspection system stage according to claim 3 wherein the final tolerance in the direction orthogonal to a plane parallel to an upper surface of the second section to within 2.5 μm of any selected lateral position.
5. The inspection system stage of claim 1 wherein characterizing physical attributes of the media is performed during continuous translation of the media through said second section.
6. The inspection system stage of claim 1 wherein characterizing physical attributes of the media is performed while holding the media stationary and then subsequently translating the media.
7. The inspection system stage of claim 1 wherein media surface height compensation is of less than 10 μm over 40 mm to adjust for thickness variations in the media.
8. The inspection system stage of claim 1 wherein the second section compnses an assembly of the second section for producing a field of controllable gas emission, and includes a mechanism that produces further both a vacuum at selected locations of the section and a second pressurized gas bearing in the field in order to controllably suspend and vertically position the media.
9. The inspection system stage of claim 1 wherein the field producing assembly comprises a porous medium.
10. The inspection system stage of claim 1 wherein the porous medium is selected from the group consisting of porous ceramics, foamed metals, porous glass, and synthetic porous materials.
11. The inspection system stage of claim 1 wherein the producing mechanism comprises vacuum ports integrated with the porous medium.