US3668634A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dynamic threshold voltage determination system
Assignee: Unisys Corp
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Filing: 1970-05-06
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Granted: 1972-06-06
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Expires: 1990-05-06
Abstract
Abstract A dynamic threshold voltage system for neutralizing the unwanted electrical signals caused by intertrack crosstalk as generated in multi-track electromagnetic transducers. The system is responsive to the amplitudes of intelligence bearing electrical signals to generate a direct current voltage threshold level which is a predetermined ratio of the intelligence bearing signal. This threshold level is applied to all of the data channels for the multi-track electromagnetic transducer to effectively neutralize any unwanted crosstalk originated signal appearing on any channel.
Inventors
- 👤 Karlis Kruklitis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 00:13
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; G11B20/10009; G06; G06V; G06V30/00; G06V30/10; G06V30/16; G06V30/162
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
277 words
In a multi-channel magnetic character recognition system, a dynamic threshold voltage system comprising: a document having a magnetically encoded character imprinted thereon, transducing means having a plurality of individual and parallel arranged electromagnetic transducers each transducer scanning a predetermined portion of the character on said document as said document moves relative to said transducing means and generating an electrical signal in response to the portion of the character scanned thereby, said electrical signal having a voltage range between a reference voltage characterizing the document and an extreme voltage characterizing the character, a plurality of diodes individually electrically connected from their cathode to each of said electromagnetic transducers and directly responsive to the electrical signal generated by said electromagnetic transducers and all the anodes of said diodes electrically connected together, threshold voltage generating means for generating a threshold voltage for differentiating between a character and the document background, said threshold voltage generating means including a voltage generating means generating a predetermined fixed threshold voltage level said fixed threshold voltage level intermediate the reference voltage and the extreme voltage of said electrical signal, and a current control member electrically connected in parallel circuit to said voltage generating means and directly responsive to the electrical signals generated by said transducer means which are directly coupled thereto by said diodes for varying the threshold voltage level according to the magnitude of the extreme voltage level of said electrical signals, and a plurality of comparator means each electrically coupled respectively to one of said electromagnetic transducers and said threshold voltage level for generating a digital electrical signal whenever said electrical signal from said transducer is greater than said threshold voltage level signal.
Claim 2
Dependent Claim
277 words
In a multi-channel magnetic character recognition system, a dynamic threshold voltage system comprising: a document having a magnetically encoded character imprinted thereon, transducing means having a plurality of individual and parallel arranged electromagnetic transducers each transducer scanning a predetermined portion of the character on said document as said document moves relative to said transducing means and generating an electrical signal in response to the portion of the character scanned thereby, said electrical signal having a voltage range between a reference voltage characterizing the document and an extreme voltage characterizing the character, a plurality of diodes individually electrically connected from their cathode to each of said electromagnetic transducers and directly responsive to the electrical signal generated by said electromagnetic transducers and all the anodes of said diodes electrically connected together, threshold voltage generating means for generating a threshold voltage for differentiating between a character and the document background, said threshold voltage generating means including a voltage generating means generating a predetermined fixed threshold voltage level said fixed threshold voltage level intermediate the reference voltage and the extreme voltage of said electrical signal, and a current control member electrically connected in parallel circuit to said voltage generating means and directly responsive to the electrical signals generated by said transducer means which are directly coupled thereto by said diodes for varying the threshold voltage level according to the magnitude of the extreme voltage level of said electrical signals, and a plurality of comparator means each electrically coupled respectively to one of said electromagnetic transducers and said threshold voltage level for generating a digital electrical signal whenever said electrical signal from said transducer is greater than said threshold voltage level signal.
Claim 3
Dependent Claim
43 words
In a magnetic character recognition system, a threshold voltage system according to claim 1 wherein said current control member is a transistor normally biased off to maintain said fixed threshold voltage level in the absence of a character at the predetermined voltage level.
Claim 4
Dependent Claim
197 words
In a multi-channel magnetic character recognition system, a dynamic threshold voltage system according to claim 1 wherein said threshold voltage generating means further comprises: a voltage source, a first resistor electrically connected at one end to the source terminal of said voltage source, a second resistor electrically connected in series with said first resistor, a third resistor electrically connected in series with said first and second resistors and electrically connected to the return terminal of said voltage source, said first, second and third resistors defining a predetermined fixed normal voltage threshold value at the junction of said second and third resistors, a transistor electrically connected in parallel circuit with said first resistor for increasing the amount of current to said second and third resistors for varying the threshold voltage generated at the junction of said second and third resistors, and control means electrically connected to the base lead said transistor and responsive to the electrical signals from said diodes for biasing said transistor off in the normal state for maintaining the predetermined fixed threshold voltage level and for operating said transistor in response to the changes in said electrical signals to increase the threshold voltage level proportionally.
References Cited (Backward Citations)
US3159815A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-06 | 1975-12-06 | 1976-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-06 | 1979-12-06 | 1980-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-06 | 1983-12-06 | 1984-06-06 | $7700.00 | Window Closed / Lapsed |