US3784912A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic zero device
Assignee: Kollmorgen Corp
•
Filing: 1972-08-11
•
Granted: 1974-01-08
•
Expires: 1992-08-11
Abstract
Abstract An automatic zeroing device for use with a measuring instrument is described. The device automatically causes the instrument to read a predetermined value, termed the zero value, in response to an input signal, regardless of the value of the input signal. The device is based on a modification of a digital to analog converter in a feedback loop which also includes a summing amplifier, receiving the input signal and a zeroing signal, and a comparator. The digital to analog converter produces the zeroing signal in response to the comparator output.
Inventors
- 👤 Aken H Van
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 17:14
CPC Classifications
G; G01; G01R; G01R17/00; G01R17/02; G01R17/06
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
229 words
A device for automatically causing a voltage responsive measuring instrument to register a predetermined reading in response to an input signal having a value other than that corresponding to said predetermined reading comprising: a. a summing amplifier receiving said input signal and a varying zeroing signal; b. a comparator, one input of which receives the output of said summing amplifier, a second input receiving a signal corresponding to said predetermined reading; c. a pulse source responsive to said comparator for producing pulse signals when the summing amplifier output does not correspond to said signal which corresponds to the predetermined reading; d. a digital to analog converter comprising a counter, incremented in response to said pulse signals, a resistive ladder network, transistor switches coupled between the stages of said counter and selected resistors of said ladder network for selectively switching said resistors into or out of said ladder network in response to the count in said counter and a ladder network summing amplifier, an input of which is coupled to said ladder network, its output supplying said zeroing signal, said zeroing signal being incrementally varied in response to the count in said counter; e. said pulse source ceasing to produce pulse signals in response to correspondence between said summing amplifier output and said signal which corresponds to the predetermined reading, said counter storing the count which resulted in said correspondence.
Claim 2
Independent Claim
229 words
A device for automatically causing a voltage responsive measuring instrument to register a predetermined reading in response to an input signal having a value other than that corresponding to said predetermined reading comprising: a. a summing amplifier receiving said input signal and a varying zeroing signal; b. a comparator, one input of which receives the output of said summing amplifier, a second input receiving a signal corresponding to said predetermined reading; c. a pulse source responsive to said comparator for producing pulse signals when the summing amplifier output does not correspond to said signal which corresponds to the predetermined reading; d. a digital to analog converter comprising a counter, incremented in response to said pulse signals, a resistive ladder network, transistor switches coupled between the stages of said counter and selected resistors of said ladder network for selectively switching said resistors into or out of said ladder network in response to the count in said counter and a ladder network summing amplifier, an input of which is coupled to said ladder network, its output supplying said zeroing signal, said zeroing signal being incrementally varied in response to the count in said counter; e. said pulse source ceasing to produce pulse signals in response to correspondence between said summing amplifier output and said signal which corresponds to the predetermined reading, said counter storing the count which resulted in said correspondence.
Claim 3
Dependent Claim
69 words
The device of claim 1 further including a trigger means for initiating a zeroing operation, said trigger means comprising a manually operable switch and means responsive to the closing of said switch for resetting said counters and for supplying an enabling signal to said pulse source, said enabling signal when combined with the comparator output when the input signals thereto do not correspond, triggering said pulse source into operation.
References Cited (Backward Citations)
US3159787A
Cited
US3509460A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-07 | 1977-07-09 | 1978-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-07 | 1981-07-09 | 1982-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-07 | 1985-07-09 | 1986-01-08 | $7700.00 | Window Closed / Lapsed |