COMPOUND OPTICAL-SENSOR SYSTEM FOR VISUALLY OBSERVING AND PHOTOELECTRICALLY SENSING CODED INDICIA

• US 3,853,403 A
• Filed: 11/12/1973
• Issued: 12/10/1974
• Est. Priority Date: 11/12/1973
• Status: Expired due to Term

• Current Assignee: George P. Bentley
• Original Assignee: George P. Bentley
• Inventors: Bentley, George P.
• Primary Examiner(s): McGraw, Vincent P.
• Application Number:
  US05/414,819
• Time in Patent Office: 393 Days
• Field of Search: 356/209,71 250/567,568 350/54,202 340/146.3F,146.3Z 235/61.11E
• US Class Current: 356/71
• CPC Class Codes: G06K 7/10831 Arrangement of optical elements, e.g. lenses, mirrors, prisms optical elements per se G02B

Abstract

Apparatus for visually observing and photo-electrically sensing coded indicia on a document. A lens system is provided for imaging the coded indicia upon apertures in a mask wherein preselected portions of the region of interest are magnified and imaged upon apertures in the mask, which apertures are smaller in size than the images aligned therewith. The portions of interest passing through their associated mask apertures are re-imaged at a plane at which is provided a photosensing device or devices. A second movable mask is provided for sequentially enabling the image at each aperture in the first mask to be directed to the photosensing plane. Additional optical elements are provided for providing a visually observable projection of the apertures in the first mask superimposed with the indicia in the region of interest, which superimposed images are so positioned relative to the actual region of interest to enable an observer to substantially simultaneously view both the region of interest and the aforesaid superimposed images to permit simple, rapid, and positive alignment of the region of interest containing the coded indicia relative to the aforesaid first mask.

Claims

1. An optical device for measuring optical reflectance characteristics of characters and other like indicia arranged upon a substrate, the reflectivity of said substrate and the reflectivity of the indicia being substantially different, said device comprising:

a first mask having a window behind which the indicia bearing region of the substrate is adjustably positioned;

means for illuminating the region of the substrate behind said window with substantially uniform flux;

a first lens arranged a spaced distance from said window and having a front surface facing said window and a rear surface remote from said window;

a second lens positioned between said window and said first lens for imaging at least a portion of the illuminated indicia in said window on the rear surface of said first lens;

relfective means along the rear surface of said first lens for reflecting rays impinging on the surface of said reflecting means, said reflective means having at least one aperture for passing rays impinging upon said aperture through said aperture;

sensing means positioned in a sensing plane located a spaced distance from the rear surface of said first lens for sensing radiation passing through said aperture;

a third lens positioned between said first lens and said sensing means for imaging the aperture stop of said second lens in said sensing plane.

2. The device of claim 1 wherein said illuminating means comprises:

first and second lamps;

third and fourth lenses each being adapted to direct radiation from its associated lamp upon said substrate behind said window to collectively illuminate the region of said substrate behind said window with substantially uniform flux.

3. The device of claim 1 wherein said illumination means comprises a lamp;

first and second mirrors positioned on opposite side of said lamp;

third and fourth condenser lenses positioned to collect light from said lamp and direct the collected light upon said first and second mirrors respectively;

said first and second mirrors each being adapted to reflect light from their associated condenser lenses in a first direction;

third and fourth mirrors being adapted to reflect light from said first and second mirrors respectively, toward said window, the reflective surfaces of said third and fourth mirrors each being at an angle of the order of 45* relative to the plane of said window.

4. The device of claim 1 further comprising movable mask means positioned between said first lens and said sensing plane, said movable mask having at least one slot;

means for moving said movable mask to selectively move said slot and thereby enabling rays passing through said reflective means aperture to pass through said slot.

5. The device of claim 4 wherein said movable mask comprises an annular shaped disc mounted to rotate about its central axis;

the slot in said movable mask being arcuate in shape.

6. The device of claim 1 wherein said first lens is a plano-convex lens;

the planar surface of said plano-convex lens constituting said rear surface.

7. The device of claim 6 wherein said reflective means comprises a reflective coating deposited upon the rear surface of said plano-convex lens.

8. The device of claim 1 wherein said second lens is adapted to magnify the images of the indicia imaged upon the rear surface of said first lens.

9. The device of claim 8 wherein the aperture in said reflective means is smaller than the magnified image of the indicia imaged upon said aperture.

10. The device of claim 9 wherein the aperture has a configuration similar to the configuration of the indicia imaged upon said aperture.

11. The device of claim 1 wherein the indicia being presented for recognition comprises a plurality of code bars arranged in a spaced pattern.

12. The device of claim 11 wherein said reflective means is provided with a second aperture spaced from said first aperture wherein the distance (D1) between the centerlines of said apertures is less than the distance (D2) between the centerlines of adjacent code bars and preferably wherein D1 1/2 DZ.

13. The device of claim 12 wherein said reflective means is provided with a third aperture;

said mask having a reference region of a predetermined reflectivity positioned adjacent said window so as to be imaged upon said third aperture by said second lens.

14. The device of claim 12 wherein said reflective means is provided with a third aperture positioned so as to receive flux reflected from a region of the substrate behind said window and spaced from said indicia, which flux is imaged upon said third aperture.

15. The device of claim 14 further comprising movable mask means positioned between said first lens and said sensing plane, said movable mask having a plurality of slots each being associated with one of the apertures in said reflective means;

means for moving said movable mask to selectively move said slots thereby enabling rays passing through said reflective means to pass through said slots in sequential fashion.

16. The device of claim 1 wherein the planes of said window and said first and second lenses are parallel;

the centers of said first and second lenses being coincident with an optical axis which forms an acute angle with an imaginary line normal to the planes of said window and said first and second lenses to thereby provide an off-axis projection arrangement, whereby rays impinging on said reflective means are directed away from said window.

17. The device of claim 16 further comprising:

a viewing screen;

optical means for imaging the aperture in said reflective means and indicia imaged on the rear surface of said first lens upon said viewing screen, said viewing screen being oriented to enable the observer to view the substrate behind said window and the viewing screen substantially simultaneously.

18. The device of claim 17 wherein said substrate is adjustable relative to said window to enable an observer to move at least one of the indicia on said substrate into registration with the aperture in said reflective means, said registration condition being observable by means of the superimposed image displayed on said viewing screen.

19. The device of claim 17 wherein said optical means comprises an achromat lens for imaging the apertures and imaged indicia at the rear surface of said first lens upon said viewing screen;

said optical means being adapted to cause any external ambient light entering said achromat lens through said screen to pass through the aperture in said reflective means and be directed along a path which is transverse to said optical axis.

20. The device of claim 19 further comprising a light trap positioned along said path and between said first lens and said viewing plane to trap any stray light directed along said path and directed generally toward said sensing means.

21. The device of claim 16 further comprising a viewing eye-piece;

means cooperating with said eye-piece for developing an aerial image of the aperture in said reflective means and the indicia imaged on the rear surface of said first lens, said superimposed aerial image being observable through the use of said eye-piece;

said eye piece being positioned to facilitate viewing of said window.

22. The device of claim 21 wherein said substrate is adjustable relative to said window to enable an observer to move at least one of the indicia on said substrate into registration with the aperture in said reflective means, said registration condition being observable by means of the superimposed image viewable through said eye-piece.