US4371768A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Arrangement for the sealing of thermoplastic-coated packing material
Assignee: Tetra Pak AB
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Filing: 1980-10-22
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Granted: 1983-02-01
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Expires: 2000-10-22
Abstract
Abstract The windings of an electromagnetic device for heat-sealing thermoplastic material having an electrically conductive layer are included as an inductive component in an oscillatory circuit, rather than merely being an external load. Two inductively coupled windings operate as a feedback element to control the alternate conduction of two transistors, to produce an oscillating signal. The core of the electromagnetic heating element has a E-shaped cross section, and the windings are wound around the middle limb of the core and are substantially surrounded by the two outer limbs to thereby substantially reduce thermal losses.
Inventors
- 👤 Laszlo Pozna
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:30
CPC Classifications
B; B29; B29C; B29C66/00; B29C66/80; B29C65/00; B29C65/02; B29C65/34; B29C65/36; B29C65/3604; B29C65/3656; B29C65/3668; B29C65/3672; B29C65/3676; B29C65/368; B29C66/01; B29C66/05; B29C66/10; B29C66/11; B29C66/112; B29C66/1122; B29C66/20; B29C66/23; B29C66/232; B29C66/40; B29C66/41; B29C66/43; B29C66/431; B29C66/4312; B29C66/70; B29C66/72; B29C66/723; B29C66/7232; B29C66/72321; B29C66/73; B29C66/739; B29C66/7392; B29C66/73921; B29C66/81; B29C66/812; B29C66/8122; B29C66/8126; B29C66/818; B29C66/8181; B29C66/81811; B29C66/81812; B29C66/90; B29C66/91; B29C66/914; B29C66/9161; B29C66/91651; B29C66/91653; B29C66/91655; B29K; B29K2705/00; B29K2705/02; B29K2995/00; B29K2995/0003; B29K2995/0008
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
131 words
Apparatus for sealing thermoplastic packing material having an electrically conducting layer, comprising: a sealing jaw including a magnetically conductive core having an E-shaped cross-section providing a middle limb which terminates at a surface that defines a sealing plane and a recess in said surface on either side of said middle limb that opens into said sealing plane; and a parallel resonant oscillator circuit comprising a first winding and a capacitor connected in parallel, and further including a second winding inductively coupled to said first winding for controlling the flow of current through said first winding, both said windings being disposed around said middle limb and within the recess in said core adjacent said sealing plane and being substantially entirely surrounded by core structure except for the opening to said sealing plane.
Claim 2
Dependent Claim
131 words
Apparatus for sealing thermoplastic packing material having an electrically conducting layer, comprising: a sealing jaw including a magnetically conductive core having an E-shaped cross-section providing a middle limb which terminates at a surface that defines a sealing plane and a recess in said surface on either side of said middle limb that opens into said sealing plane; and a parallel resonant oscillator circuit comprising a first winding and a capacitor connected in parallel, and further including a second winding inductively coupled to said first winding for controlling the flow of current through said first winding, both said windings being disposed around said middle limb and within the recess in said core adjacent said sealing plane and being substantially entirely surrounded by core structure except for the opening to said sealing plane.
Claim 3
Dependent Claim
20 words
The apparatus of claim 1 wherein said oscillator circuit further includes a pair of semiconductors operatively connected to said windings.
Claim 4
Dependent Claim
16 words
The apparatus of claim 1 wherein said core has a length substantially greater than its width.
Claim 5
Dependent Claim
30 words
The apparatus of claim 1 wherein said core is cylindrical in shape and has an annular groove defining said recess and said middle limb around which said windings are disposed.
Claim 6
Dependent Claim
12 words
The apparatus of claim 1 wherein said core is made of ferrite.
Claim 7
Dependent Claim
169 words
Apparatus for sealing thermoplastic packing material having an electrically conducting layer, comprising: a magnetically conductive core having a surface that defines a sealing plane and a recess in said surface that opens into said sealing plane; and a parallel resonant oscillator circuit comprising a first winding and a capacitor connected in parallel, a second winding inductively coupled to said first winding for controlling the flow of current through said first winding, both said windings being disposed within the recess in said core adjacent said sealing plane and being substantially entirely surrounded by core structure except for the opening to said sealing plane, a resistor connected between the midpoints of said windings, a pair of semiconductors having their base terminals respectively connected to the end terminals of said second winding, their collector terminals respectively connected to the end terminals of said first winding and their emitter terminals connected to each other, and a d.c. power supply connected between the junction of said emitters and the midpoint of said first winding.
Claim 8
Dependent Claim
169 words
Apparatus for sealing thermoplastic packing material having an electrically conducting layer, comprising: a magnetically conductive core having a surface that defines a sealing plane and a recess in said surface that opens into said sealing plane; and a parallel resonant oscillator circuit comprising a first winding and a capacitor connected in parallel, a second winding inductively coupled to said first winding for controlling the flow of current through said first winding, both said windings being disposed within the recess in said core adjacent said sealing plane and being substantially entirely surrounded by core structure except for the opening to said sealing plane, a resistor connected between the midpoints of said windings, a pair of semiconductors having their base terminals respectively connected to the end terminals of said second winding, their collector terminals respectively connected to the end terminals of said first winding and their emitter terminals connected to each other, and a d.c. power supply connected between the junction of said emitters and the midpoint of said first winding.
Claim 9
Dependent Claim
23 words
The apparatus of claim 6 wherein said second winding has fewer turns and is made with a smaller wire than said first winding.
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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) | 1986-01-31 | 1986-08-02 | 1987-02-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-01-31 | 1990-08-02 | 1991-02-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-01-31 | 1994-08-02 | 1995-02-01 | $7700.00 | Window Closed / Lapsed |