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US5446272A
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System for digitizing a scanned signal indicating changes in signal intensity
Assignee: Symbol Technologies LLC
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Filing: 1994-06-08
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Granted: 1995-08-29
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Expires: 2014-06-08
Abstract
Abstract A system for digitizing an analog electric signal generated from a photoelectronic conversion of reflected light when scanning indicia having specifically-separated, light-reflective portions. The system detects zero-crossings of the second derivative signal, and ignores noise signals from a first derivative of the analog signal.
Inventors
- 👤 Edward Barkan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 14:11
CPC Classifications
G; G06; G06K; G06K7/00; G06K7/10; G06K7/10544; G06K7/10554; G06K7/10564; G06K7/10584; G06K7/10594; G06K7/10603; G06K7/10633; G06K7/10643; G06K7/10653; G06K7/10673; G06K7/10683; G06K7/10693; G06K7/10792; G06K7/10801; G06K7/10811; G06K7/10821; G06K7/10851; G06K7/10861; G06K7/10871; G06K7/10881; G06K7/10891; G06K7/109; G06K7/14; G06K7/1404; G06K7/146; G06K7/1478; G06K2207/00; G06K2207/1011; G06K2207/1016; G06K2207/1018
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
100 words
A circuit for digitizing an analog electric signal generated from a photoelectronic conversion of reflected light when scanning indicia having spatially-separated, light-reflective portions, comprising: differentiator circuit means for generating a second derivative signal representing a second derivative of the analog signal; means, responsive to the second derivative signal, for detecting zero-crossings of the second derivative signal; means for ignoring noise signals originating from a first derivative of the analog signal; and output means, responsive to the ignoring means and coupled to the zero-crossing detecting means, for generating an output signal indicating a change in the intensity of the reflected light.
Claim 2
Dependent Claim
100 words
A circuit for digitizing an analog electric signal generated from a photoelectronic conversion of reflected light when scanning indicia having spatially-separated, light-reflective portions, comprising: differentiator circuit means for generating a second derivative signal representing a second derivative of the analog signal; means, responsive to the second derivative signal, for detecting zero-crossings of the second derivative signal; means for ignoring noise signals originating from a first derivative of the analog signal; and output means, responsive to the ignoring means and coupled to the zero-crossing detecting means, for generating an output signal indicating a change in the intensity of the reflected light.
Claim 3
Dependent Claim
22 words
The circuit of claim 1, further comprising a margin threshold circuit to control passing of the output signal from the output means.
Claim 4
Dependent Claim
22 words
The circuit of claim 2, further including an automatic gain control for maintaining a desired signal level for the margin threshold circuit.
Claim 5
Dependent Claim
14 words
The circuit of claim 1, wherein the zero-crossing detecting means includes a comparator circuit.
Claim 6
Dependent Claim
27 words
The circuit of claim 1, wherein the noise signal ignoring means includes a comparator circuit designed to have a hysteresis characteristic set at a predetermined signal level.
Claim 7
Dependent Claim
25 words
The circuit of claim 5, further including an automatic gain control for maintaining the predetermined signal level for the hysteresis characteristic of the comparator circuit.
Claim 8
Dependent Claim
55 words
The circuit of claim 1, wherein the output means includes an output comparator for comparing an output signal from the zero-crossing detecting means and an output signal from the noise signal ignoring means, the output comparator responding to transitions in the output signal from the zero-crossing detecting means subsequent to responding to the ignoring means.
Claim 9
Dependent Claim
18 words
The circuit of claim 1, wherein the second differentiator circuit means includes a capacitor coupled to a resistor.
Claim 10
Independent Claim
93 words
A method for digitizing an analog signal generated from a photoelectronic conversion of reflected light when scanning indicia having spatially-separated, light-reflective portions, the method comprising the steps of: generating a second derivative signal representing a second derivative of the analog signal; detecting zero-crossings of the second derivative signal and generating a detected output signal; ignoring noise signals originating from a first derivative signal of the analog signal and generating a noise-free signal; and generating an output signal indicating a change in the intensity of the reflected light in response to the ignoring step.
Claim 11
Independent Claim
93 words
A method for digitizing an analog signal generated from a photoelectronic conversion of reflected light when scanning indicia having spatially-separated, light-reflective portions, the method comprising the steps of: generating a second derivative signal representing a second derivative of the analog signal; detecting zero-crossings of the second derivative signal and generating a detected output signal; ignoring noise signals originating from a first derivative signal of the analog signal and generating a noise-free signal; and generating an output signal indicating a change in the intensity of the reflected light in response to the ignoring step.
Claim 12
Dependent Claim
26 words
The method of claim 9, further comprising the step of controlling passing of the output signal from the output means in accordance with a predetermined threshold.
Claim 13
Dependent Claim
23 words
The method of claim 10, further including the step of maintaining a desired signal level of the output signal from the output means.
Claim 14
Dependent Claim
26 words
The method of claim 9, wherein the detecting step includes the step of comparing a signal level of the second derivative signal to a zero reference.
Claim 15
Dependent Claim
29 words
The method of claim 9, wherein the ignoring step includes the step of triggering the first derivative signal at a predetermined signal level above and below a zero reference.
Claim 16
Dependent Claim
53 words
The method of claim 13, wherein the generating step includes the step of comparing the detected signal from the zero-crossing detecting step and the noise-free signal from the noise signal ignoring step, the output signal from the generating step responding to transitions in the detected signal only after responding to the noise-free signal.
Claim 17
Dependent Claim
15 words
The method of claim 13, further including the step of maintaining the predetermined signal level.
Claim 18
Dependent Claim
21 words
The method of claim 9, further comprising the step of regulating the first derivative signal using an automatic gain control (AGC).
Claim 19
Dependent Claim
21 words
The method of claim 9, further comprising the step of preventing saturation affects due to sunlight in the first derivative signal.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-08-28 | 1999-02-27 | 1999-08-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-08-28 | 2003-02-27 | 2003-08-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-08-28 | 2007-02-27 | 2007-08-29 | $7700.00 | Window Closed / Lapsed |