US3928800A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Calorimetric resistance bridges
Assignee: SP-MICROWAVE Inc
•
Filing: 1973-06-25
•
Granted: 1975-12-23
•
Expires: 1993-06-25
Abstract
Abstract Calorimetrically sensitive resistance bridges are adapted for providing a read out which is a linear function of power, either in analog or digital display form, by duty cycle control of power pulses applied across the bridge for re-balancing purposes.
Inventors
- 👤 Harry F Strenglein
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 13:00
CPC Classifications
G; G01; G01R; G01R17/00; G01R17/02; G01R21/00; G01R21/02
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
116 words
Measurement apparatus comprising: multiple arm bridge circuit means having in one arm first and second impedance means, said first impedance means being sensitive to an effect to be measured, said second impedance means being cyclically variable between first and second values, low pass amplifier means responsive to the state of balance of said bridge circuit means, feed back means responsive to said low pass amplifier means for resetting the balance of said bridge circuit means, display means, synchronizer means for cyclically switching said second impedance means between said first and second values, said synchronizer means being further adapted synchronously to couple and decouple capacitive means responsive to said low pass amplifier means to said display means.
Claim 2
Dependent Claim
116 words
Measurement apparatus comprising: multiple arm bridge circuit means having in one arm first and second impedance means, said first impedance means being sensitive to an effect to be measured, said second impedance means being cyclically variable between first and second values, low pass amplifier means responsive to the state of balance of said bridge circuit means, feed back means responsive to said low pass amplifier means for resetting the balance of said bridge circuit means, display means, synchronizer means for cyclically switching said second impedance means between said first and second values, said synchronizer means being further adapted synchronously to couple and decouple capacitive means responsive to said low pass amplifier means to said display means.
Claim 3
Dependent Claim
25 words
Apparatus as described in claim 1 wherein said first impedance means comprises a thermal sensor and said bridge includes second, third, and fourth impedance arms.
Claim 4
Dependent Claim
48 words
Apparatus as described in claim 2 wherein said low pass amplifier means comprises: low pass circuit means responsive to the state of balance of said bridge circuit means, and astable pulse generator means responsive to said low pass circuit means for producing a variable duty cycle pulse train.
Claim 5
Dependent Claim
16 words
Apparatus as described in claim 3 wherein said low pass circuit means comprises differential amplifier means.
Claim 6
Dependent Claim
25 words
Apparatus as described in claim 3 further including saturating amplifier means coupled in series relation between said astable generator means and said feed back means.
Claim 7
Dependent Claim
40 words
Apparatus as described in claim 3 further including means for sampling each pulse of said pulse train supplied to said display means only after each transient caused by the finite time constant of said first impedance means has substantially ended.
References Cited (Backward Citations)
US2565922A
Cited
US2710397A
Cited
US3048778A
Cited
US3183438A
Cited
US3378828A
Cited
US3382430A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-22 | 1979-06-23 | 1979-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-22 | 1983-06-23 | 1983-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-22 | 1987-06-23 | 1987-12-23 | $7700.00 | Window Closed / Lapsed |