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Synchronous Shutter for Start/Stop Circuit Exposure

IP.com Disclosure Number: IPCOM000075502D
Original Publication Date: 1971-Sep-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Lozier, WB: AUTHOR

Abstract

A faster, more accurate and reliable shutter for printed circuit exposure results when the shutter is supported in gas bearings. These bearings eliminate friction and allow the shutter inertia to be the principal driving force when used in a moving single-axis exposure head. Theoretically, a frictionless shutter mechanism should perform the synchronous shutter motion by inertia alone during acceleration and deceleration, but supplementary drive and hold controls are required in practice.

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Synchronous Shutter for Start/Stop Circuit Exposure

A faster, more accurate and reliable shutter for printed circuit exposure results when the shutter is supported in gas bearings. These bearings eliminate friction and allow the shutter inertia to be the principal driving force when used in a moving single-axis exposure head. Theoretically, a frictionless shutter mechanism should perform the synchronous shutter motion by inertia alone during acceleration and deceleration, but supplementary drive and hold controls are required in practice.

Figs. 1, 2, and 3 are elevation, plan and side views of the shutter mechanism on which is mounted an expose head mechanism. Shutter 1 is L-shaped and supported between right-angle gas bearing surfaces 2 and 3 downward, along optical axis 5, through reticle 6 toward the workpiece below. A retractable light stop 7 operates to block illumination during idle periods and permits positioning of the shutter to either side initially. Shutter 1 is initially positioned by selectively energizing electromagnetic coils 9 and 10 at opposite ends. The shutter may also be used for controlled-flash exposure by selectively energizing electromagnetic coils 9 and 10 when the expose head is stationary. Actual shutter position is detected by fixed low-voltage differential transformer 11 with its core 12 secured to the shutter. The transformer signal is used in conjunction with programmed acceleration and deceleration positioning signals for actuating...