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US3793533A
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US
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Electrical safety control circuit
Assignee: Precision Electronic Components Ltd
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Filing: 1973-03-16
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Granted: 1974-02-19
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Expires: 1993-03-16
Abstract
Abstract A safety control circuit for punch presses and the like has two push buttons which must be pressed almost simultaneously, each push button permitting discharge of a capacitor through a different relay coil. The relay coils move switches from first to second positions to connect to a power supply an electrical device which controls the punch press or the like. To ensure that the circuit fails safe, each relay coil has at least a pair of switches, and in their first positions the switches of these pairs are all connected in series between one side of the capacitor and the power supply. The other side of the capacitor may be grounded.
Inventors
- 👤 L Ginsberg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:41
CPC Classifications
B; B21; B21D; B21D55/00; F; F16; F16P; F16P3/00; F16P3/18; F16P3/20
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
114 words
A safety circuit for energizing an electrical device, comprising a capacitor, a first and a second relay each having a pair of switches, said switches all having first positions in which they are connected in series with the capacitor for charging the capacitor from a power supply, each relay having a coil connectable across the capacitor through a closable switch for energization of the coil by discharge of the capacitor therethrough, each coil when so energized moving its said switches to second positions, one switch of each pair in its second position being in series with one switch of the other pair in its second position for connecting said device to the power supply.
Claim 2
Dependent Claim
114 words
A safety circuit for energizing an electrical device, comprising a capacitor, a first and a second relay each having a pair of switches, said switches all having first positions in which they are connected in series with the capacitor for charging the capacitor from a power supply, each relay having a coil connectable across the capacitor through a closable switch for energization of the coil by discharge of the capacitor therethrough, each coil when so energized moving its said switches to second positions, one switch of each pair in its second position being in series with one switch of the other pair in its second position for connecting said device to the power supply.
Claim 3
Dependent Claim
31 words
A circuit as claimed in claim 1, wherein said relay switches are in their first positions in series between one side of the capacitor and one side of the power supply.
Claim 4
Dependent Claim
16 words
A circuit as claimed in claim 2, wherein the other side of the capacitor is grounded.
Claim 5
Dependent Claim
21 words
A circuit as claimed in claim 2, including means for supplementing the charge on the capacitor for energization of the coils.
Claim 6
Dependent Claim
57 words
A circuit as claimed in claim 4, wherein said supplementing means comprise a second capacitor and a third switch of one of the relays for connecting the second capacitor to the power supply in the first position of the switches and for connecting the second capacitor across the first capacitor in the second position of the switches.
Claim 7
Dependent Claim
39 words
A circuit as claimed in claim 4, wherein said supplementing means comprise a series connection of the other switches of each pair when in said second positions to reconnect said one side of the capacitor to the power supply.
Claim 8
Dependent Claim
42 words
A circuit as claimed in claim 6, including a current limiting resistor in series with the switches of said pairs in their first positions but bypassed by the series connection of said other switches of said pairs when in their second positions.
References Cited (Backward Citations)
US2962633A
Cited
US3089985A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-18 | 1977-08-20 | 1978-02-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-18 | 1981-08-20 | 1982-02-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-18 | 1985-08-20 | 1986-02-19 | $7700.00 | Window Closed / Lapsed |