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US3787707A
Expired / Lapsed
US
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Spark detector apparatus and method
Assignee: Ransburg Corp
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Filing: 1973-05-16
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Granted: 1974-01-22
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Expires: 1993-05-16
Abstract
Abstract A spark detector for electrostatic coating apparatus which distinguishes disruptive discharges in the electrostatic system from a corona discharge or random sparking of other electrical equipment. A frequency selective radio wave receiver is connected with an envelope detector, the output of which is analyzed to detect the presence of repetitive discharges.
Inventors
- 👤 P Gregg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 10:03
CPC Classifications
B; B05; B05B; B05B5/00; B05B5/08; B05B5/10; B05B5/087; H; H02; H02H; H02H1/00; H02H1/0007; H02H1/0015; H02H7/00; H02H7/003
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
162 words
A detector for a disruptive discharge which may occur in a zone in which a high intensity electric field is established between a charged electrode and an electrical reference, said electrode being connected with one terminal of a high voltage DC power supply which has a reference terminal connected with said electrical reference, said zone being subject to corona discharge from said electrode, said detector comprising: an antenna having a circuit returned to said electrical reference and characterized by an absence of a connection with the path of current flow through said high voltage power supply, said antenna receiving electromagnetic energy radiated from a disruptive discharge and from said corona; a tuned amplifier connected with said antenna circuit and having a passband excluding the frequencies of corona discharge; an envelope detector connected with said amplifier for detecting the occurrence of a disruptive discharge in said zone; and utilization circuit means connected with said detector and responsive to detection of a disruptive discharge.
Claim 2
Dependent Claim
162 words
A detector for a disruptive discharge which may occur in a zone in which a high intensity electric field is established between a charged electrode and an electrical reference, said electrode being connected with one terminal of a high voltage DC power supply which has a reference terminal connected with said electrical reference, said zone being subject to corona discharge from said electrode, said detector comprising: an antenna having a circuit returned to said electrical reference and characterized by an absence of a connection with the path of current flow through said high voltage power supply, said antenna receiving electromagnetic energy radiated from a disruptive discharge and from said corona; a tuned amplifier connected with said antenna circuit and having a passband excluding the frequencies of corona discharge; an envelope detector connected with said amplifier for detecting the occurrence of a disruptive discharge in said zone; and utilization circuit means connected with said detector and responsive to detection of a disruptive discharge.
Claim 3
Dependent Claim
20 words
The detector of claim 1 in which said envelope detector has a time constant of the order of 50 microseconds.
Claim 4
Dependent Claim
23 words
The detector of claim 1 in which the passband of said tuned amplifier has a center frequency of the order of 100 kilohertz.
Claim 5
Dependent Claim
57 words
The detector of claim 1 in which said utilization circuit means includes a timing circuit for establishing a timing period, means responsive to detection of a first discharge for actuating said timing circuit and further circuit means responsive to detection of a second disruptive discharge occurring during said timing period for causing response of said utilization circuit.
Claim 6
Dependent Claim
31 words
The detector of claim 4 in which said timing circuit means includes a monostable multivibrator having a first condition and a second condition and a gate circuit responsive to said multivibrator.
Claim 7
Dependent Claim
18 words
The detector of claim 5 in which said multivibrator includes a relay having contacts in said gate circuit.
Claim 8
Dependent Claim
45 words
The detector of claim 1 wherein there is a conductive article in said zone, nominally maintained at said reference potential, but subject to undesired isolation from the reference potential and, when so isolated, acquiring an induced electrostatic charge which may discharge to said reference potential.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-21 | 1977-07-23 | 1978-01-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-21 | 1981-07-23 | 1982-01-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-21 | 1985-07-23 | 1986-01-22 | $7700.00 | Window Closed / Lapsed |