Apparatus and techniques for evacuat- ing and sealing a semi-rigid plastic tray
Abstract
Abstract PACKAGING APPARATUS AND TECHNIQUES FOR FORMING EVACUATED PACKAGES OF THE TYPE COMPRISING A SEMI-RIGID (FORMRETAINING) CONTAINER TRAY CARRYING A PRODUCT TO BE PACKAGED, AND A COVER SHEET OF PLASTIC MATERIAL HEAT-SEALED TO THE TRAY PERIPHERY AND DRAWN (STRETCHED) DOWN INTO THE TRAY TO EFFECT A TIGHT ENGAGEMENT WITH THE UPPER SUFACES OF THE PACKAGED PRODUCT. THE APPARATUS COMPRISES RECIPROCABLE MEMBERS DEFINING A CHAMBER WITHIN WHICH THE PACKAGE IS EV ACUATED, AND THE COVER SHEET HEAT-SEALED TO THE TRAY. THE HEATING MEANS IN THE CHAMBER IS ARRANGED TO SUPPLY HEAT TO THE COVER SHEET WHILE THE PACKAGE IS EVACUATED, SO THAT WHEN THE CHAMBER IS VENTED, ATMOSPERIC PRESSURE STRETCHES THE HEATED PLASTIC INTO THE TRAY.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-06-07 | 1974-12-07 | 1975-06-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-07 | 1978-12-07 | 1979-06-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-07 | 1982-12-07 | 1983-06-08 | $7700.00 | Window Closed / Lapsed |