US5177343A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Symbol reader using differentiating circuit for light beam focusing
Assignee: Sumitomo Electric Industries Ltd
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Filing: 1990-12-19
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Granted: 1993-01-05
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Expires: 2010-12-19
Abstract
Abstract A symbol reader for reading symbols on a symbol surface. An optical system including a laser, condensing lens and scanning mirror illuminate a symbol surface to be read with a laser beam, scanning across the symbol surface. A transducer measures the amount of light reflected from the symbol surface. A differentiating circuit develops a differential coefficient indicative of the change of light intensity as light scans the symbols being read. A control system adjusts the optical system illuminating the symbol surface so as to maximize the differential coefficient, thereby minimizing the diameter of the light beam to allow for adequate reading of the symbol surface at variable distances.
Inventors
- 👤 Shinya Takenaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 04:32
CPC Classifications
G; G06; G06K; G06K7/00; G06K7/10; G06K7/10544; G06K7/10821; G06K7/10851; G06K2207/00; G06K2207/1018
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
152 words
A symbol reader for reading a symbol from a symbol surface, comprising: means for illuminating the symbol surface with a read beam of light, the illuminating means including: a light source, a first condensing lens for condensing light from the light source, and scan mirror means for scanning a symbol surface and symbols to be read with light transmitted through the first condensing lens; a transducing element for receiving light reflected from the symbols and symbol surface, and producing a read signal indicative of the intensity of reflected light; differential coefficient means, responsive to the read signal, for providing a differential coefficient indicative of intensity change in the reflected light; control means, responsive to the differential coefficient, for adjusting a distance between said first condensing lens and said light source to maximize the amplitude of the differential coefficient; and means for processing the read signal so as to interpret the scanned symbols.
Claim 2
Dependent Claim
152 words
A symbol reader for reading a symbol from a symbol surface, comprising: means for illuminating the symbol surface with a read beam of light, the illuminating means including: a light source, a first condensing lens for condensing light from the light source, and scan mirror means for scanning a symbol surface and symbols to be read with light transmitted through the first condensing lens; a transducing element for receiving light reflected from the symbols and symbol surface, and producing a read signal indicative of the intensity of reflected light; differential coefficient means, responsive to the read signal, for providing a differential coefficient indicative of intensity change in the reflected light; control means, responsive to the differential coefficient, for adjusting a distance between said first condensing lens and said light source to maximize the amplitude of the differential coefficient; and means for processing the read signal so as to interpret the scanned symbols.
Claim 3
Dependent Claim
17 words
A device according to claim 1 wherein the scan mirror means comprises a movable mirrored surface element.
Claim 4
Dependent Claim
27 words
A device according to claim 1, wherein the scan mirror means comprises a mirrored surface element which can revolve in a fixed plane about its central axis.
Claim 5
Dependent Claim
22 words
A device according to claim 1, wherein the scan mirror means comprises an element having a plurality of reflecting and polarizing surfaces.
Claim 6
Dependent Claim
23 words
A device according to claim 1, wherein the scan mirror means comprises a polygon-shaped element having a plurality of reflecting and polarizing surfaces.
Claim 7
Dependent Claim
25 words
A device according to claim 1, further comprising a second condensing lens positioned so as focus light from the symbol surface onto the transducing element.
Claim 8
Dependent Claim
49 words
A device according to claim 1, wherein the differential coefficient means comprises: a differential circuit for determining the differential coefficient from the read signal, storage means for storing the maximum or minimum amplitude value of the differential coefficient, and means for outputting the stored value as the differential coefficient.
Claim 9
Dependent Claim
15 words
A device according to claim 1, wherein the differential coefficient means comprises a hardwired circuit.
Claim 10
Dependent Claim
35 words
A device according to claim 1, wherein the differential coefficient means comprises: means for converting the read signal into a digital signal; and microcomputer means for processing the digital signal to provide the differential coefficient.
Claim 11
Dependent Claim
30 words
A device according to claim 1, wherein the control means comprises means for displacing the first condensing lens in a direction along the optical axis of the first condensing lens.
Claim 12
Dependent Claim
21 words
A device according to claim 10 wherein the means for displacing the first condensing lens comprises a motor and drive arrangement.
Claim 13
Dependent Claim
30 words
A device according to claim 10, wherein the control means further comprises means for displacing the light source in a direction along the optical axis of the first condensing lens.
Claim 14
Dependent Claim
29 words
A device according to claim 1, wherein the control means comprises means for displacing the light source in a direction along the optical axis of the first condensing lens.
Claim 15
Dependent Claim
14 words
A device according to claim 1 wherein the light source is a semiconductor laser.
Claim 16
Dependent Claim
14 words
A device according to claim 1 wherein the light source is a gas laser.
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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) | 1996-01-05 | 1996-07-06 | 1997-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-01-05 | 2000-07-06 | 2001-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-01-05 | 2004-07-06 | 2005-01-05 | $7700.00 | Window Closed / Lapsed |