US3833883A
Expired / Lapsed
US
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Threshold forming circuit
Assignee: Licentia Patent Verwaltungs GmbH
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Filing: 1973-03-23
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Granted: 1974-09-03
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Expires: 1993-03-23
Abstract
Abstract A threshold forming circuit for use in a character recognition system includes a plurality of scanners and associated signal processing channels, arranged in scanning groups. Threshold values are produced for use in evaluating the signals in each of the processing channels. The threshold values are generated by a signal processing circuit in dependence upon the scanning signals. The signal processing circuit includes a plurality of processing units, where there is one such unit associated with each scanning group. Each unit includes a maximum amplitude filter which is connected to each of the signal processing channels of the respective group and generates an output signal dependent upon the highest scanning signal in the group. A group threshold setting circuit is connected within each of the units to the maximum amplitude filter and produces a threshold value which is dependent upon the signal from its associated maximum amplitude filter and the signals generated by the filters of the other scanning groups. This threshold value is then utilized in a threshold circuit for assisting in the evaluation of the signals on the processing channels.
Inventors
- 👤 G Haupt
- 👤 W Kochert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:09
CPC Classifications
G; G06; G06V; G06V30/00; G06V30/10; G06V30/16; G06V30/162
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
242 words
In a system for forming a threshold value for use in evaluating the scanning signals produced by a plurality of scanners and processed in an associated plurality of processing channels of a character recognition apparatus, the scanners and their associated processing channels being arranged in scanning groups, which threshold circuit includes a plurality of first threshold value setting means each associated with the processing channels of a respective group for establishing a separate threshold value for each group which is dependent upon the highest scanning signal value being produced by the scanners of the respective group, and second threshold value setting means connected to all of the groups for providing a common minimum threshold value for all processing channels, which minimum value is dependent upon the highest scanning signal value being produced by the scanners of all groups, the improvement wherein said second threshold valve setting means comprises a signal distortion circuit connected to produce an output signal whose value is proportional to the common minimum threshold value, said circuit comprising an operational amplifier and feedback means connected between the output and the input of said amplifier to provide non-linear feedback therefor, and said circuit constituting means for causing the value of such output signal to vary nonlinearly with variations in such highest scanning signal value in a manner such that the value of such output signal varies at a rate which increases as the value of such highest scanning signal increases.
Claim 2
Dependent Claim
242 words
In a system for forming a threshold value for use in evaluating the scanning signals produced by a plurality of scanners and processed in an associated plurality of processing channels of a character recognition apparatus, the scanners and their associated processing channels being arranged in scanning groups, which threshold circuit includes a plurality of first threshold value setting means each associated with the processing channels of a respective group for establishing a separate threshold value for each group which is dependent upon the highest scanning signal value being produced by the scanners of the respective group, and second threshold value setting means connected to all of the groups for providing a common minimum threshold value for all processing channels, which minimum value is dependent upon the highest scanning signal value being produced by the scanners of all groups, the improvement wherein said second threshold valve setting means comprises a signal distortion circuit connected to produce an output signal whose value is proportional to the common minimum threshold value, said circuit comprising an operational amplifier and feedback means connected between the output and the input of said amplifier to provide non-linear feedback therefor, and said circuit constituting means for causing the value of such output signal to vary nonlinearly with variations in such highest scanning signal value in a manner such that the value of such output signal varies at a rate which increases as the value of such highest scanning signal increases.
Claim 3
Dependent Claim
86 words
An arrangement as defined in claim 1 further comprising a plurality of threshold circuit means, each coupled to a respective group of processing channels, each said threshold circuit means also being coupled to said first threshold value setting means of its respective group and to said second threshold value setting means for comparing each of the scanning signals of the associated group with the higher one of the separate threshold value produced by its associated first threshold value setting means and the common minimum threshold value.
Claim 4
Dependent Claim
46 words
An arrangement as defined in claim 1 wherein said feedback means comprises a resistor and a transistor having its emitter-collector path connected in parallel with said resistor, the parallel arrangement of said resistor and transistor being connected to said amplifier to form a feedback path therefor.
Claim 5
Dependent Claim
37 words
An arrangement as defined in claim 1 wherein each said first means is also connected to the first means of the adjacent groups, for effecting the setting of each of the threshold values by said first means.
Claim 6
Dependent Claim
91 words
A circuit as defined in claim 4 wherein said first and second means are interconnected for causing the first threshold value produced by each said first means to be the higher one of a first value equal to a set percentage of the highest scanning signal value being produced by the scanners of the associated group voltage output from the associated first filter means and a second value dependent upon both the common minimum threshold value and the highest scanning signal values being produced by the scanners of the adjacent groups.
Claim 7
Dependent Claim
216 words
An arrangement as defined in claim 1 further comprising, for each said group, first maximum amplitude filter means connected to each of the signal processing channels of the respective scanning group for generating an output signal dependent upon the highest scanning signal in said scanning group, aNd wherein each said first threshold value setting means comprises: setting means connected to said first filter means for producing a signal equal to a set percentage of the voltage output from said first filter means, said setting means including an amplifier means for amplifying the output signal from said first filter means and a resistance network means including first and second resistors and being coupled to the output of said amplifier means for providing the set percentage of the amplified signal in accordance with the ratio between the resistance value of said first resistor and the resistance value of said second resistor; resistance means having inputs connected to receive the output signals from said first filter means of the adjacent groups and the minimum threshold value from said second threshold value setting means, for providing an output signal dependent upon these signals; and further maximum amplitude filter means connected to said setting means and said resistance means for producing an output selected from the higher of the signals therefrom.
Claim 8
Dependent Claim
39 words
A circuit as defined in claim 1 wherein each said first threshold value setting means produces a threshold value equal to a set percentage of the highest scanning signal value being produced by the scanners of its associated group.
Claim 9
Dependent Claim
33 words
A circuit as defined in claim 1 wherein only one of two scanning groups receives scanning signals at any one time, said two scanning groups have a common first threshold value setting means.
References Cited (Backward Citations)
US3560931A
Cited
US3701099A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-02 | 1978-03-04 | 1978-09-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-02 | 1982-03-04 | 1982-09-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-02 | 1986-03-04 | 1986-09-03 | $7700.00 | Window Closed / Lapsed |