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Publication numberUS3684866 A
Publication typeGrant
Publication dateAug 15, 1972
Filing dateJul 9, 1970
Priority dateJul 9, 1970
Publication numberUS 3684866 A, US 3684866A, US-A-3684866, US3684866 A, US3684866A
InventorsPaul W Jones
Original AssigneeIdenticon Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Scanning aperture
US 3684866 A
An optical label scanning system has a parallelogram-shaped aperture for scanning.
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Claims  available in
Description  (OCR text may contain errors)

United States Patent Jones [451 Aug. 15, 1972 SCANNING APERTURE [56] References Cited [72] Inventor: Paul W. Jones, Franklin, Mass. UNITED STATES PATENTS [731 AssigneeI ldemicon Corporation, Waltham, 3,243,776 3/1966 Abbott, Jr. eta] ..340/l46.3

Mass 3,351,765 11/1967 Malone et al. ..250/2l9 D [22] Filed: July 9, 1970 Primary Examinen lhomas A. Robinson [21] PP N05 53,499 Attorney-Charles Hieken [52] US. Cl. ..-235/61.l1 E, 250/219 D ABSTRACT [51] Int. Cl. A i l l b l canning ystem has a parallelogram- [58] Field of Search.....340/l46.3, 146.3 K; 250/233,

250/219 D, 219 DC; 235/6l.1l F

shaped aperture for scanning.

2 Claims, 2 Drawing Figures PATENTEDAuc 1 5 I972 FIG. 1

FIG. 2'

PAU L W. JONES lnven/or M AI/omey SCANNING APERTURE BACKGROUND OF THE INVENTION The present invention relates in general to scanning apertures and more particularly concerns a novel scanning aperture especially useful in scanning labels and coding information in a vertical array of horizontal bars to provide maximum coverage without bar-to-bar overlap while achieving a significant improvement in signal-tonoise ratio. Yet the structure is relatively easy and inexpensive to fabricate.

A typical prior art scanning aperture is a circle having a diameter chosen to provide maximum coverage without bar-to-bar overlap. For example, if the narrowest bar is of width a and the separation between bars is also of width a, the diameter ofa typical circular aperture is also a.

It is an important object of this invention to provide an optical scanning system having an improved scanning aperture.

It is another object of the invention to achieve the preceding object while increasing signal-to-noise ratio.

It is a further object of the invention to achieve one or more of the preceding objects with essentially no increase in cost.

SUMMARY OF THE INVENTION According to the invention, means define a generally parallelogram-shaped aperture.

Numerous other features, objects and advantages of the invention will become apparent from the following specification when read in connection with the accompanying drawing in which:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic view of the image of label stripes super-imposed upon a mask having a circular aperture according to the prior art; and

FIG. 2 is a plan view of a mask according to the invention having a parallelogram-shaped aperture with the outline of a circular aperture superimposed by broken lines to illustrate the increased aperture area available with a parallelogram-shaped aperture while still retaining wide latitude for angular disorientation.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS With reference now to the drawing and more particularly FIG. 1 thereof, there is shown a mask formed with a circular aperture 11 of diameter a corresponding to the width of the narrow stripes and the separation a therebetween with the image of narrow stripes 12 and 13 and broad stripe l4 superimposed upon mask 10.

Referring to FIG. 2, there is shown a mask formed with a parallelogram-shaped aperture 21 with a circle designated by the broken lines 22 to facilitate comparison between the two openings. The parallelogramshaped aperture 21 has a height a corresponding to the diameter a of circle 22, this height being the minor diagonal of the parallelogram illustrated. The major diagonal is perpendicular to the scanning direction. The sides are parallel to the maximum axes of rotation and form an angle of 6. The area of the parallelogram may be larger, equal to or less than the circle 22 of diameter corresponding to the height of the parallelogram, depending upon the value of 0.

It can be shown that a parallelogranrshapcd aperture will scan a larger portion of each bar than a circular aperture without bar-to-bar overlap by increasing its area without sacrificing resolution and still providing good latitude for angular misorientation of the label.

The critical value of 0 where the areas of parallelogram and circle of the same height are equal may be derived as follows:

Thus, for allowable misalignment angles of less than 325 from the horizontal, a parallelogram-shaped apertureaccording to the invention will scan a larger portion of each bar than a circular aperture without bar-to-bar overlap. At the same time it will allow considerably more latitude in angular misalignment of the bars than a horizontal slit aperture.

The particular scanning system in which the mask is used is known in the art and not described herein so as not to obscure the principles of the invention. For a description of a suitable scanning system, reference is made to U.S. Pat. No. 3,225,177 entitled MARK SENSING granted Dec. 21, I965, to Stites et al. A mask according to the invention would be substituted for the mask 50 with a slit aperture there shown.

There has been described novel apparatus and techniques for developing a significant improvement in signal-to-noise ratio while still retaining acceptably wide latitude in optical misalignment of stripes being scanned. For example, the increase in scanning area over a circular aperture is of the order of percent for 6 20". Since the noise is frequently limited by the type of detector rather than non-bar return and signal strength is directly proportional to aperture area, a significant signal-to-noise ratio improvement is realizable through the use of a parallelogram-shaped aperture according to the invention.

It is evident that those skilled in the art may now make numerous uses and modifications of and departures from the specific embodiments and techniques disclosed herein without departing from the inventive concepts. Consequently, the invention is to be construed as embracing each and every novel feature and novel combination of features present in or possessed by the apparatus and techniques herein disclosed.

What is claimed is:

1. In an optical scanning system for scanning stripes having lengths and widths normally respectively perpendicular and parallel to the scanning direction and separated by a separation a, said system having masking means formed with an aperture for restricting the cross sectional area of light rays that may impinge upon a photo-detector masked by said masking means,

the improvement comprising,

means defining an aperture in said mask that is parallelogram-shaped with the major diagonal thereof perpendicular to said scanning direction and the minor diagonal corresponding to said separation a between stripes, said aperture defining an area slit aperture. 2. The improvement according to claim I wherein the angle subtended by the minor diagonal is less than substantially 65.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3243776 *Feb 8, 1963Mar 29, 1966Ncr CoScanning system for registering and reading characters
US3351765 *Oct 31, 1966Nov 7, 1967Ex Cell O CorpPhotosensitive read-out device for apertured records
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3832529 *May 7, 1973Aug 27, 1974Seiwa Seikosha KkReading system for tags encoded with bars of different widths
US4408120 *Feb 26, 1982Oct 4, 1983Nippondenso Co., Ltd.Bar code scanner
US5484994 *Oct 18, 1993Jan 16, 1996Roustaei; AlexanderOptical scanning head with improved resolution
US5786582 *Dec 8, 1995Jul 28, 1998Symbol Technologies, Inc.Optical scanner for reading and decoding one- and two-dimensional symbologies at variable depths of field
US6488208Jul 8, 1999Dec 3, 2002Sick AgBar code reading apparatus
US7573491 *Jul 7, 2005Aug 11, 2009David HartkopMethod for formatting images for angle-specific viewing in a scanning aperture display device
US20050264560 *Jul 7, 2005Dec 1, 2005David HartkopMethod for formating images for angle-specific viewing in a scanning aperture display device
DE19830553A1 *Jul 8, 1998Jan 13, 2000Sick AgBarcode-Lesevorrichtung
EP0061000A1 *Feb 19, 1982Sep 29, 1982Nippondenso Co., Ltd.Bar code scanner
EP0971307A2 *Jun 22, 1999Jan 12, 2000Sick AGBarcode reading device
U.S. Classification250/566, 235/462.35, 250/568
International ClassificationG06K7/10
Cooperative ClassificationG06K7/10831
European ClassificationG06K7/10S9B
Legal Events
Jul 26, 1983AS02Assignment of assignor's interest
Effective date: 19830426
Jul 26, 1983ASAssignment
Effective date: 19830426