US4478077A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flow sensor
Assignee: Honeywell Inc
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Filing: 1982-09-30
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Granted: 1984-10-23
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Expires: 2002-09-30
Abstract
Abstract A flow sensor comprising a pair of thin film heat sensors and a thin film heater is disclosed. The flow sensor further comprises a semiconductor body with a depression therein and structure connecting the heater and the sensors to the body and bridging the depression so that at least a major portion of the heater and the sensors are out of contact with the body. The sensors are disposed on opposite sides of the heater, the structure connecting comprising two thin film members bridging the depression, each member comprising one sensor and a portion of the heater.
Inventors
- 👤 Philip J. Bohrer
- 👤 Robert G. Johnson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 04:35
CPC Classifications
G; G01; G01F; G01F1/00; G01F1/68; G01F1/696; G01F1/684; G01F1/6845; G01F1/698; G01F1/699
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
89 words
A flow sensor, comprising: a thin film heater; a pair of thin film sensors; a semiconductor body with a depression therein; and means connecting the heater and the sensors to the body and bridging the depression so that at least a major portion of the heater and the sensors are out of contact with the body and with the sensors disposed on opposite sides of the heater, the means connecting comprising two thin film members bridging the depression, each member comprising one sensor and a portion of the heater.
Claim 2
Dependent Claim
89 words
A flow sensor, comprising: a thin film heater; a pair of thin film sensors; a semiconductor body with a depression therein; and means connecting the heater and the sensors to the body and bridging the depression so that at least a major portion of the heater and the sensors are out of contact with the body and with the sensors disposed on opposite sides of the heater, the means connecting comprising two thin film members bridging the depression, each member comprising one sensor and a portion of the heater.
Claim 3
Dependent Claim
88 words
A flow sensor comprising: a thin film heater encapsulated in thin film dielectric; a pair of thin film sensors encapsulated in thin film dielectric, the sensors being disposed on opposite sides of the heater; a semiconductor body with a depression therein; and the encapsulated heater and sensors forming two thin film members bridged across the depression so that at least a major portion of the heater and the sensors are out of contact with the semiconductor body, each member comprising one sensor and a portion of the heater.
Claim 4
Dependent Claim
88 words
A flow sensor comprising: a thin film heater encapsulated in thin film dielectric; a pair of thin film sensors encapsulated in thin film dielectric, the sensors being disposed on opposite sides of the heater; a semiconductor body with a depression therein; and the encapsulated heater and sensors forming two thin film members bridged across the depression so that at least a major portion of the heater and the sensors are out of contact with the semiconductor body, each member comprising one sensor and a portion of the heater.
Claim 5
Dependent Claim
105 words
A flow sensor comprising: a semiconductor body having a depression formed into a first surface of the body; a thin film heater encapsulated in thin film dielectric; and a pair of thin film sensors encapsulated in thin film dielectric, the thin film sensors being disposed on opposite sides of the heater; the encapsulated heater and sensors forming two thin film members, the two thin film members being attached to the first surface at least at one location in order to suspend at least a major portion of the heater and sensors over the depression, each member comprising one sensor and a portion of the heater.
Claim 6
Dependent Claim
105 words
A flow sensor comprising: a semiconductor body having a depression formed into a first surface of the body; a thin film heater encapsulated in thin film dielectric; and a pair of thin film sensors encapsulated in thin film dielectric, the thin film sensors being disposed on opposite sides of the heater; the encapsulated heater and sensors forming two thin film members, the two thin film members being attached to the first surface at least at one location in order to suspend at least a major portion of the heater and sensors over the depression, each member comprising one sensor and a portion of the heater.
Claim 7
Dependent Claim
69 words
The apparatus of claim 1, 2, or 3 wherein the heater is operated at a temperature elevated above ambient, thus creating a no-flow temperature gradient in the air above and adjacent to the heater, the temperature within the no-flow gradient making a transition between the elevated temperature and substantially ambient temperature, the sensors being located sufficiently close to the heater to be located substantially within the no-flow temperature gradient.
Claim 8
Dependent Claim
47 words
The apparatus of claim 1, 2, or 3 wherein the sensors are located from the heater at a preferred distance which, when contrasted to an alternate distance, provides a substantially greater change in the heat being delivered to the sensors for a given change in flow rate.
Claim 9
Dependent Claim
38 words
The apparatus of claim 1, 2, or 3 wherein the proximal edges of the sensors are located from the near edges of the heater at a distance within the range of approximately 5 microns to approximately 25 microns.
Claim 10
Dependent Claim
63 words
The apparatus of claim 1, 2, or 3 wherein the heater and each sensor comprise a resistive element having a pattern of resistive material formed in lines having a line width, the lines being separated by substantially a line width, the sensors being separated from the heater by a distance in the range of approximately one line width to approximately five line widths.
Claim 11
Dependent Claim
20 words
The apparatus of claim 1, 2, or 3 wherein the thin film heater and sensors each comprise a permalloy element.
Claim 12
Dependent Claim
28 words
The apparatus of claim 8 wherein each permalloy element has a resistance in the range of approximately 200 ohms to approximately 2000 ohms at approximately 25 degrees Centigrade.
Claim 13
Dependent Claim
24 words
The apparatus of claim 2 or 3 wherein the dielectric has a thickness in the range of approximately 0.8 micron to approximately 1.2 microns.
Claim 14
Dependent Claim
13 words
The apparatus of claim 2 or 3 wherein the dielectric comprises silicon nitride.
Claim 15
Dependent Claim
59 words
The apparatus of claim 2 or 3 wherein: the semiconductor body comprises (100) silicon having a (100) plane and a [110] direction; the heater and sensors lie in a plane substantially parallel to the (100) plane; and the means connecting the heater and sensors to the body have a configuration oriented at a non-zero angle to the [110] direction.
Claim 16
Dependent Claim
13 words
The apparatus of claim 12 wherein the non-zero angle is substantially 45 degrees.
Claim 17
Dependent Claim
23 words
The apparatus of claim 8 wherein each permalloy element has a thickness in the range of approximately 800 angstroms to approximately 1600 angstroms.
Claim 18
Dependent Claim
19 words
The apparatus of claim 1, 2, or 3 wherein the two thin film members are connected by an interconnect.
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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) | 1987-10-23 | 1988-04-23 | 1988-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-10-23 | 1992-04-23 | 1992-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-10-23 | 1996-04-23 | 1996-10-23 | $7700.00 | Window Closed / Lapsed |