US3586772A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Second order video clipper for optical character reader
Assignee: International Business Machines Corp
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Filing: 1968-05-24
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Granted: 1971-06-22
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Expires: 1988-05-24
Abstract
Abstract An optical character reader providing output signals proportional to the lightness or blackness of the document being scanned generates a clipping level voltage which is not a fixed percentage of the peak black minus peak white signals. The clipping level percentage varies with the density, or blackness, of the character. The black and white peak signals are applied to a differentially connected operational amplifier having an output proportional to a first multiple times the black peak minus a second multiple times the white peak, where the first and second multiples are unequal. The output of the operational amplifier is added to a signal proportional to white background thereby providing a clipping level which is a variable percentage of the difference between a black and white peak signal.
Inventors
- 👤 William W Hardin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 23:18
CPC Classifications
G; G06; G06V; G06V10/00; G06V10/10; G06V30/00; G06V30/10; G06V30/16; G06V30/162
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
97 words
In an optical scanning system of the type which scans a document containing characters and develops electrical signals proportional to the degree of blackness and whiteness intercepted by the scan, a clipping-level generator comprising: amplifier means responsive to first and second input signals representing peak blackness and peak whiteness of said electrical signals; means coupled to said amplifier means for generating an output signal which is a nonlinear function of the difference between said first signal and said second signal, and means for adding said output signal to a signal representing the white background of said document.
Claim 2
Dependent Claim
97 words
In an optical scanning system of the type which scans a document containing characters and develops electrical signals proportional to the degree of blackness and whiteness intercepted by the scan, a clipping-level generator comprising: amplifier means responsive to first and second input signals representing peak blackness and peak whiteness of said electrical signals; means coupled to said amplifier means for generating an output signal which is a nonlinear function of the difference between said first signal and said second signal, and means for adding said output signal to a signal representing the white background of said document.
Claim 3
Dependent Claim
47 words
A clipping-level generator as claimed in claim 1 wherein said amplifier means is an operational amplifier having first and second differential input terminals and an output terminal, and wherein said means for generating said output signal is coupled to at least one of said differential input terminals.
Claim 4
Dependent Claim
42 words
A clipping-level generator as claimed in claim 2 wherein said output signal is proportional in amplitude to the difference between a first multiple of said first signal and a second multiple of said second signal, said first and second multiples being unequal.
Claim 5
Dependent Claim
79 words
A clipping-level generator as claimed in claim 3 wherein said means for generating said output signal comprises: a feedback resistor connected between one of said differential inputs and said output terminal, a reference resistor connected between the other of said differential inputs and a reference potential, said reference resistor being unequal to said feedback resistor, and a pair of input resistors connected to said differential input terminals for connecting said first and second signals to said differential input terminals.
Claim 6
Dependent Claim
18 words
A clipping-level generator as claimed in claim 4 wherein said reference resistor is greater than said feedback resistor.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-06-21 | 1974-12-21 | 1975-06-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-21 | 1978-12-21 | 1979-06-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-21 | 1982-12-21 | 1983-06-22 | $7700.00 | Window Closed / Lapsed |