US4568922A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ice deposition detector employing impedance change of a vibratory body
Assignee: NEDERLANDSE CENTRALE ORGANISATIE VOOR TOEGEPAST-NATUURWETENSCHAPPELIJKONDERZOEK
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Filing: 1983-07-18
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Granted: 1986-02-04
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Expires: 2003-07-18
Abstract
Abstract A vibrating body is connected as one element of a voltage divider. A detector circuit is connected to the measuring point of the voltage divider. If ice is deposited on the body, its impedance changes and the resulting voltage change at the voltage divider is detected to provide an alarm or control function. The noted impedance change can be more reliably detected under a variety of conditions than the traditional vibration frequency or amplitude criteria.
Inventors
- 👤 Gustaaf A. Schwippert
- 👤 Louter W. van der Kolk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 19:52
CPC Classifications
G; G01; G01N; G01N29/00; G01N29/02; G01N29/036; G01N2291/00; G01N2291/02; G01N2291/025; G01N2291/0256
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
181 words
An apparatus for detecting deposition of ice or the like, comprising a vibrator adapted to be caused to vibrate by means of an electrical vibration source, a surface of said vibrator being adapted to be exposed to the deposition, means for detecting changes in the vibration of said vibrator when deposition takes place, and an output circuit for producing an output signal when the deposit has exceeded a given limit, characterized in that the vibration source is a sweeping oscillator (1, 2) having, in the active condition, a frequency which periodically varies within a range comprising the resonant frequencies of the vibrator (4) at the prevailing deposits, in that said oscillator (1, 2) is connected to a voltage divider formed by a series connection of the vibrator (4) and an impedance (5), and in that the means for detecting a change in the vibration (7-12; 14-23) are connected to a measuring point (6) of this voltage divider (4, 5), and are adapted to detect voltage changes across a part of this voltage divider caused by impedance changes of the vibrator (4).
Claim 2
Independent Claim
181 words
An apparatus for detecting deposition of ice or the like, comprising a vibrator adapted to be caused to vibrate by means of an electrical vibration source, a surface of said vibrator being adapted to be exposed to the deposition, means for detecting changes in the vibration of said vibrator when deposition takes place, and an output circuit for producing an output signal when the deposit has exceeded a given limit, characterized in that the vibration source is a sweeping oscillator (1, 2) having, in the active condition, a frequency which periodically varies within a range comprising the resonant frequencies of the vibrator (4) at the prevailing deposits, in that said oscillator (1, 2) is connected to a voltage divider formed by a series connection of the vibrator (4) and an impedance (5), and in that the means for detecting a change in the vibration (7-12; 14-23) are connected to a measuring point (6) of this voltage divider (4, 5), and are adapted to detect voltage changes across a part of this voltage divider caused by impedance changes of the vibrator (4).
Claim 3
Dependent Claim
41 words
The apparatus of claim 1, characterised in that the measuring point (6) of the voltage divider (4, 5) is connected to one input of a comparator stage (7; 17), the other input thereof being adapted to supply thereto a reference voltage.
Claim 4
Dependent Claim
56 words
The apparatus of claim 2, characterised in that the output of the comparator stage (7) is connected to a stage (11) adapted to filter out the frequency of the vibration source, and that the output of said filter stage (11) is connected to a stage (12) adapted to detect the presence of pulses at this output.
Claim 5
Dependent Claim
41 words
The apparatus of claim 2 or 3, characterised in that between the vibration source (1, 2) and the second input of the comparator stage (7), a rectifier with variable output voltage (8, 9, 10) is inserted as a reference voltage source.
Claim 6
Dependent Claim
45 words
The apparatus of claim 2, characterised in that the measuring point (6) of the voltage divider (4, 5) is connected to a circuit (14, 15) for forming the envelope of the voltage in the measuring point (6) and determining an extreme value of said envelope.
Claim 7
Dependent Claim
36 words
The apparatus of claim 5, characterised in that between the measuring point (6) and the second input of the comparator (17) a low-pass filter (16) is connected, passing the mean voltage in the measuring point (6).
Claim 8
Dependent Claim
39 words
The apparatus of claim 1 characterised in that the output circuit is formed by two adjustable threshold circuits (18, 20; 19, 21), adapted to produce an output signal when the deposit has reached an upper or lower limit respectively.
Claim 9
Dependent Claim
108 words
The apparatus of claim 1, said vibrator comprising a vibrator plate provided with an electrode on each side, which plate is adapted to be mounted with one side fixed in good heat contact on a surface to be monitored, characterised in that the electrode (26) on the not-fixed side of the plate (24) is connected to a connecting point (30) at the other side, which connecting point and the connecting point (30) of the other electrode (25) are situated in a cavity (29) of an intermediate body (28) of a good heat conducting material and situated between the vibrator plate (24) and the surface to be monitored (33).
Claim 10
Dependent Claim
19 words
The apparatus of claim 8, characterised in that the crystal plate (24) is covered by an insulating layer (27).
References Cited (Backward Citations)
US3270330A
Cited
US4176524A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-02-03 | 1989-08-05 | 1990-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-02-03 | 1993-08-05 | 1994-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-02-03 | 1997-08-05 | 1998-02-04 | $7700.00 | Window Closed / Lapsed |