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US4876732A
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System for detecting rotational angle of objective pattern
Assignee: Fuji Electric Co Ltd
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Filing: 1987-05-18
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Granted: 1989-10-24
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Expires: 2007-05-18
Abstract
Abstract A system and method for determining a rotational angle of an objective pattern which involves calculating the area A and linear moments M x and M y of the pattern from binary picture elements formed after optically sensing the pattern. The picture elements are stored in the memory in binary form. The center of gravity of the objective pattern is calculated on the basis of the area A and the linear moments M x and M y , and a circular or ring-like search region (a window) is formed about that center of gravity. Thereafter, significant picture information in the search region is extracted from the picture information stored in the memory (in either an inverted or non-inverted state). The rotational angle of the objective pattern is then determined either by using a moment of inertia method or a inter two-gravity centers method calculation. The selection between the moment of inertia method and the inter two-gravity centers method can be performed by means of pre-set switch state information.
Inventors
- 👤 Michiaki Miyagawa
- 👤 Yutaka Ishizaka
- 👤 Shoji Shimomura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:56
CPC Classifications
G; G06; G06V; G06V30/00; G06V30/10; G06V30/14; G06V30/146; G06V30/1475; G06V30/1478
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
218 words
A method for detecting a rotational angle of an objective pattern comprising the steps of: (a) optically sensing an objective pattern by a picture sensor to form a sense signal; (b) binary coding said sense signal into picture elements; (c) calculating an area of said objective pattern and a plurality of linear moments of said objective pattern from said picture elements; (d) calculating a center of gravity of said objective pattern from said area and said linear moments; (e) storing said area, linear moments, center of gravity and said binary-coded picture elements into a memory; (f) calculating a displacement of said center of gravity corresponding to a difference between a center of gravity of a predetermined picture sample and said center of gravity of said objective pattern; (g) determining an appropriate search region from among said binary-coded picture elements and reading out data corresponding to said search region; (h) normalizing a position of said search region; (i) calculating a rotational angle for said objective pattern based on predetermined mathematical formulae and utilizing said stored information; and (j) storing predetermined data for determining whether said logic state of said picture information is to be inverted, and as to which one of said methods of calculation are to be used in detection of said rotational angle of said objective pattern.
Claim 2
Independent Claim
218 words
A method for detecting a rotational angle of an objective pattern comprising the steps of: (a) optically sensing an objective pattern by a picture sensor to form a sense signal; (b) binary coding said sense signal into picture elements; (c) calculating an area of said objective pattern and a plurality of linear moments of said objective pattern from said picture elements; (d) calculating a center of gravity of said objective pattern from said area and said linear moments; (e) storing said area, linear moments, center of gravity and said binary-coded picture elements into a memory; (f) calculating a displacement of said center of gravity corresponding to a difference between a center of gravity of a predetermined picture sample and said center of gravity of said objective pattern; (g) determining an appropriate search region from among said binary-coded picture elements and reading out data corresponding to said search region; (h) normalizing a position of said search region; (i) calculating a rotational angle for said objective pattern based on predetermined mathematical formulae and utilizing said stored information; and (j) storing predetermined data for determining whether said logic state of said picture information is to be inverted, and as to which one of said methods of calculation are to be used in detection of said rotational angle of said objective pattern.
Claim 3
Dependent Claim
19 words
The method of claim 1, further including the step of forming a search region by using a normalization process.
Claim 4
Independent Claim
191 words
A system for detecting a rotational angle of a two-dimensional objective pattern converted into binary picture information, said system comprising: memory means for storing said picture information; first feature extraction means for extracting an area and a moment of inertia of said objective pattern from said picture information; center of gravity means for determining a center of gravity of said objective pattern from said area and said moment of inertia of said objective pattern; region forming means performing a search region having a predetermined shape about said center of gravity of said pattern; second feature extraction means for extracting a selective portion of said picture information out of said memory means, whereby said rotational angle of said objective pattern is detected on the basis of said extracted portion by using a selected one of a moment of inertia method or an inter two-centers of gravity method of calculation; and predetermined data storage means for determining whether said logic state of said picture information is to be inverted, and as to which one of said methods of calculation are to be used in detection of said rotational angle of said objective pattern.
Claim 5
Independent Claim
191 words
A system for detecting a rotational angle of a two-dimensional objective pattern converted into binary picture information, said system comprising: memory means for storing said picture information; first feature extraction means for extracting an area and a moment of inertia of said objective pattern from said picture information; center of gravity means for determining a center of gravity of said objective pattern from said area and said moment of inertia of said objective pattern; region forming means performing a search region having a predetermined shape about said center of gravity of said pattern; second feature extraction means for extracting a selective portion of said picture information out of said memory means, whereby said rotational angle of said objective pattern is detected on the basis of said extracted portion by using a selected one of a moment of inertia method or an inter two-centers of gravity method of calculation; and predetermined data storage means for determining whether said logic state of said picture information is to be inverted, and as to which one of said methods of calculation are to be used in detection of said rotational angle of said objective pattern.
Claim 6
Dependent Claim
26 words
A system for detecting rotational angle of an objective pattern according to claim 3, in which said search region is formed by using a normalization process.
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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) | 1992-10-23 | 1993-04-24 | 1993-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-10-23 | 1997-04-24 | 1997-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-10-23 | 2001-04-24 | 2001-10-24 | $7700.00 | Window Closed / Lapsed |