US4478076A
Expired / Lapsed
US
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Flow sensor
Assignee: Honeywell Inc
•
Filing: 1982-09-30
•
Granted: 1984-10-23
•
Expires: 2002-09-30
Abstract
Abstract A flow sensor comprising a pair of thin film heat sensors and a thin film heater is disclosed. A base supports the sensors and heater out of contact with the base with the sensors disposed on opposite sides of the heater. The heater is operated at a constant temperature above ambient temperature under both flow and no-flow conditions. Also disclosed is a flow sensor wherein a portion of the depression is devoid of a side wall.
Inventors
- 👤 Philip J. Bohrer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 05:16
CPC Classifications
G; G01; G01F; G01F1/00; G01F1/68; G01F1/696; G01F1/698; G01F1/684; G01F1/6845; G01P; G01P5/00; G01P5/10; G01P5/12
Claims Analysis
Total Claims: 76
Claim 1
Independent Claim
50 words
A flow sensor, comprising: a thin film heater suspended in air; a pair of thin film heat sensors suspended in air and disposed on opposite sides of the heater; and means for operating the thin film heater at a constant temperature above ambient temperature under both flow and no-flow conditions.
Claim 2
Dependent Claim
50 words
A flow sensor, comprising: a thin film heater suspended in air; a pair of thin film heat sensors suspended in air and disposed on opposite sides of the heater; and means for operating the thin film heater at a constant temperature above ambient temperature under both flow and no-flow conditions.
Claim 3
Dependent Claim
71 words
A flow sensor, comprising: a thin film heater; a pair of thin film heat sensors; a semiconductor body supporting the heater and sensors with at least a major portion of the heater and sensors out of contact with the body and with the sensors disposed on opposite sides of the heater; and means for operating the thin film heater at a constant temperature above ambient under both flow and no-flow conditions.
Claim 4
Dependent Claim
71 words
A flow sensor, comprising: a thin film heater; a pair of thin film heat sensors; a semiconductor body supporting the heater and sensors with at least a major portion of the heater and sensors out of contact with the body and with the sensors disposed on opposite sides of the heater; and means for operating the thin film heater at a constant temperature above ambient under both flow and no-flow conditions.
Claim 5
Dependent Claim
87 words
A flow sensor, comprising: a thin film heater; a pair of thin film sensors; a semiconductor body with a depression therein; 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; and means for operating the thin film heater at a constant temperature above ambient temperature under both flow and no-flow conditions.
Claim 6
Dependent Claim
87 words
A flow sensor, comprising: a thin film heater; a pair of thin film sensors; a semiconductor body with a depression therein; 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; and means for operating the thin film heater at a constant temperature above ambient temperature under both flow and no-flow conditions.
Claim 7
Dependent Claim
64 words
The apparatus of claim 1, 2, or 3 wherein the constant temperature above ambient temperature creates 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
26 words
The apparatus of claim 3 wherein the means connecting the heater and the sensors to the body comprises a dielectric encapsulating the heater and the sensors.
Claim 14
Dependent Claim
22 words
The apparatus of claim 10 wherein the dielectric has a thickness in the range of approximately 0.8 micron to approximately 1.2 microns.
Claim 15
Dependent Claim
11 words
The apparatus of claim 10 wherein the dielectric comprises silicon nitride.
Claim 16
Dependent Claim
57 words
The apparatus of claim 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 17
Dependent Claim
13 words
The apparatus of claim 13 wherein the non-zero angle is substantially 45 degrees.
Claim 18
Dependent Claim
99 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; the encapsulated heater and sensors forming at least one thin film member 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; and means for operating the thin film heater at a constant temperature above ambient temperature under both flow and no-flow conditions.
Claim 19
Dependent Claim
99 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; the encapsulated heater and sensors forming at least one thin film member 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; and means for operating the thin film heater at a constant temperature above ambient temperature under both flow and no-flow conditions.
Claim 20
Dependent Claim
118 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; 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 at least one thin film member, the at least one thin film member 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; and means for operating the thin film heater at a constant temperature above ambient temperatures under both flow and no-flow conditions.
Claim 21
Dependent Claim
118 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; 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 at least one thin film member, the at least one thin film member 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; and means for operating the thin film heater at a constant temperature above ambient temperatures under both flow and no-flow conditions.
Claim 22
Dependent Claim
63 words
The apparatus of claim 15 or 16 wherein the constant temperature above ambient temperature creates 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 23
Dependent Claim
46 words
The apparatus of claim 15 or 16 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 24
Dependent Claim
37 words
The apparatus of claim 15 or 16 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 25
Dependent Claim
62 words
The apparatus of claim 15 or 16 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 26
Dependent Claim
19 words
The apparatus of claim 15 or 16 wherein the thin film heater and sensors each comprise a permalloy element.
Claim 27
Dependent Claim
28 words
The apparatus of claim 21 wherein each permalloy element has a resistance in the range of approximately 200 ohms to approximately 2000 ohms at approximately 25 degrees Centigrade.
Claim 28
Dependent Claim
24 words
The apparatus of claim 15 or 16 wherein the dielectric has a thickness in the range of approximately 0.8 micron to approximately 1.2 microns.
Claim 29
Dependent Claim
11 words
The apparatus of claim 23 wherein the dielectric comprises silicon nitride.
Claim 30
Dependent Claim
42 words
The apparatus of claim 15 or 16 wherein the semiconductor body comprises: an element for sensing the ambient temperature; and a circuit for maintaining the temperature of the heater at a constant value above ambient temperature during both flow and no-flow conditions.
Claim 31
Dependent Claim
59 words
The apparatus of claim 15 or 16 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 32
Dependent Claim
78 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 a 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, a portion of the depression being devoid of a side wall.
Claim 33
Dependent Claim
78 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 a 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, a portion of the depression being devoid of a side wall.
Claim 34
Dependent Claim
22 words
The apparatus of claim 27 wherein an upstream portion of the depression is open to receive flow unimpeded by a side wall.
Claim 35
Dependent Claim
68 words
The apparatus of claim 27 or 28 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 36
Dependent Claim
46 words
The apparatus of claim 27 or 28 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 37
Dependent Claim
37 words
The apparatus of claim 27 or 28 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 38
Dependent Claim
62 words
The apparatus of claim 27 or 28 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 39
Dependent Claim
19 words
The apparatus of claim 27 or 28 wherein the thin film heater and sensors each comprise a permalloy element.
Claim 40
Dependent Claim
28 words
The apparatus of claim 33 wherein each permalloy element has a resistance in the range of approximately 200 ohms to approximately 2000 ohms at approximately 25 degrees Centigrade.
Claim 41
Dependent Claim
28 words
The apparatus of claim 27 or 28 wherein the means connecting the heater and the sensors to the base comprise a dielectric encapsulating the heater and the sensors.
Claim 42
Dependent Claim
22 words
The apparatus of claim 35 wherein the dielectric has a thickness in the range of approximately 0.8 micron to approximately 1.2 microns.
Claim 43
Dependent Claim
11 words
The apparatus of claim 35 wherein the dielectric comprises silicon nitride.
Claim 44
Dependent Claim
59 words
The apparatus of claim 27 or 28 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 45
Dependent Claim
13 words
The apparatus of claim 38 wherein the non-zero angle is substantially 45 degrees.
Claim 46
Dependent Claim
90 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 at least one thin film member 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; a portion of the depression being devoid of a side wall.
Claim 47
Dependent Claim
90 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 at least one thin film member 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; a portion of the depression being devoid of a side wall.
Claim 48
Dependent Claim
22 words
The apparatus of claim 40 wherein an upstream portion of the depression is open to receive flow unimpeded by a side wall.
Claim 49
Dependent Claim
68 words
The apparatus of claim 40 or 41 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 50
Dependent Claim
46 words
The apparatus of claim 40 or 41 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 51
Dependent Claim
62 words
The apparatus of claim 40 or 41 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 52
Dependent Claim
19 words
The apparatus of claim 40 or 41 wherein the thin film heater and sensors each comprise a permalloy element.
Claim 53
Dependent Claim
28 words
The apparatus of claim 45 wherein each permalloy element has a resistance in the range of approximately 200 ohms to approximately 2000 ohms at approximately 25 degrees Centigrade.
Claim 54
Dependent Claim
24 words
The apparatus of claim 40 or 41 wherein the dielectric has a thickness in the range of approximately 0.8 micron to approximately 1.2 microns.
Claim 55
Dependent Claim
11 words
The apparatus of claim 47 wherein the dielectric comprises silicon nitride.
Claim 56
Dependent Claim
42 words
The apparatus of claim 40 or 41 wherein the semiconductor body comprises: an element for sensing the ambient temperature; and a circuit for maintaining the temperature of the heater at a constant value above ambient temperature during both flow and no-flow conditions.
Claim 57
Dependent Claim
59 words
The apparatus of claim 40 or 41 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 58
Dependent Claim
13 words
The apparatus of claim 50 wherein the non-zero angle is substantially 45 degrees.
Claim 59
Dependent Claim
109 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 at least one thin film member, the at least one thin film member 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, a portion of the depression being devoid of a side wall.
Claim 60
Dependent Claim
109 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 at least one thin film member, the at least one thin film member 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, a portion of the depression being devoid of a side wall.
Claim 61
Dependent Claim
22 words
The apparatus of claim 52 wherein an upstream portion of the depression is open to receive flow unimpeded by a side wall.
Claim 62
Dependent Claim
68 words
The apparatus of claim 52 or 53 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 63
Dependent Claim
46 words
The apparatus of claim 52 or 53 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 64
Dependent Claim
37 words
The apparatus of claim 52 or 53 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 65
Dependent Claim
62 words
The apparatus of claim 52 or 53 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 66
Dependent Claim
19 words
The apparatus of claim 52 or 53 wherein the thin film heater and sensor each comprise a permalloy element.
Claim 67
Dependent Claim
28 words
The apparatus of claim 58 wherein each permalloy element has a resistance in the range of approximately 200 ohms to approximately 2000 ohms at approximately 25 degrees Centigrade.
Claim 68
Dependent Claim
24 words
The apparatus of claim 52 or 53 wherein the dielectric has a thickness in the range of approximately 0.8 micron to approximately 1.2 microns.
Claim 69
Dependent Claim
11 words
The apparatus of claim 60 wherein the dielectric comprises silicon nitride.
Claim 70
Dependent Claim
42 words
The apparatus of claim 52 or 53 wherein the semiconductor body comprises: an element for sensing the ambient temperature; and a circuit for maintaining the temperature of the heater at a constant value above ambient temperature during both flow and no-flow conditions.
Claim 71
Dependent Claim
59 words
The apparatus of claim 52 or 53 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 72
Dependent Claim
13 words
The apparatus of claim 63 wherein the non-zero angle is substantially 45 degrees.
Claim 73
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 74
Dependent Claim
23 words
The apparatus of claim 21 wherein each permalloy element has a thickness in the range of approximately 800 angstroms to approximately 1600 angstroms.
Claim 75
Dependent Claim
23 words
The apparatus of claim 45 wherein each permalloy element has a thickness in the range of approximately 800 angstroms to approximately 1600 angstroms.
Claim 76
Dependent Claim
37 words
The apparatus of claim 40 or 41 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.
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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 |