FOCUS DETECTOR

• US 3,684,374 A
• Filed: 07/29/1970
• Issued: 08/15/1972
• Est. Priority Date: 07/29/1970
• Status: Expired due to Term

• Current Assignee: Allergan Humphrey
• Original Assignee: William E. Humphrey
• Inventors: Humphrey, William E.
• Primary Examiner(s): Borchelt, Benjamin A.
• Assistant Examiner(s): Buczinski, S. C.
• Application Number:
  US05/059,222
• Time in Patent Office: 748 Days
• Field of Search: 356/4,163 250/211R,22M
• US Class Current: 356/3.15
• CPC Class Codes: G02B 7/305 using a scanner

Abstract

Correspondingly located portions of images projected on separate planes are compared for coincidence by correspondingly located photosensitive elements on each of the planes. The photosensitive elements on each corresponding image location on each plane are connected in separate circuits. An electrical potential is applied across these separate circuits. This produces a first aggregate current flow at image coincidence and a second easily distinguishable aggregate current flow at image non-coincidence. By the expedient of offsetting first and second electrically connected groups of the corresponding photosensitive elements on each plane in opposing directions and isolating the aggregate current flow of these groups, the amount and direction of image displacement can be determined in a base leg optical device. When these first and second electrically connected groups of photosensitive elements are connected as one of the sides of a bridge circuit, automating ranging and focusing can be achieved as a function of circuit potential at the circuit bridge.

Claims

1. A deVice detecting image coincidence between two images taken from spaced-apart positions of a substantially identical field comprising:

first and second parallel and spaced apart back to back planes upon which back to back images of the field from each point is formed on the first and second planes respectively, means dividing each plane into a matrix of discrete electrically isolated areas in which each area on one of the planes is comparable to a similar area on the other of the planes with reference to the field, photoelectric transducer means formed at each area on each of said planes, means for connecting the photoelectric transducer means of comparable areas on each of the planes in separate series electrical circuits including a plurality of discrete conductors disposed from a comparable area on said first plane to a comparable area on said second plane; and

means for measuring the aggregate current flow in said series circuits for detecting a first current flow measurement at image coincidence on said planes and second and different current measurement flows at image noncoincidence.

2. The combination of claim 1 and wherein said discrete electrically isolated areas on said first plane are offset a predetermined amount to receive a different and adjacent segment of said field relative to said comparable electrically isolated areas on said second plane when images are superimposed on said planes in precise back to back relation.

3. The combination of claim 1 and wherein said photoelectric transducer means are photo-resistive transducer means.

4. The combination of claim 1 and where each of said image planes has photoelectric transducer means comprising a continuous coating of photosensitive material on said image planes and said means dividing each plane into a matrix of discrete electronically isolated areas includes first and second conductors extending over said first and second planes respectively defining open non-conductive areas adjacent each of said comparable areas.

5. The combination of claim 1 and wherein said means for measuring the aggregate current flow includes means for electrically connecting each of the separate series circuits between comparable areas on each of the planes in a parallel circuit.

6. Apparatus for comparing paired images of an object comprising:

first and second image planes;

means for projecting one of said paired images on one of said planes and the other of said images on the other of said planes;

means for dividing the surface of said planes into a matrix of first and second groups of paired corresponding discrete electrically isolated areas with respect to said projected images, the areas of said first group on said first and second image planes being offset in a preselected direction to receive a different and adjacent segment of each of said images with respect to the areas of said second group on said first and second image planes;

phototransducer means formed at each area on each of said planes;

first means for connecting the transducer means at corresponding areas in said first group in first separate electrical circuits extending between said first and second planes, second means for connecting the transducer means at corresponding areas in said second group in second separate electrical circuits extending between said first and second planes, first means for measuring the aggregate current flow in said first circuits; and

second means for measuring the aggregate current flow in said second circuits.

7. A base leg optical device including:

first and second planes with each plane disposed for receiving first and second images of a focused object;

means for defining first and second spatially separated light paths, each light path being focused at said first and second planes;

each said image plane having first and second matrices of discrete electrical photosensitive areas thereon, said first matrix on each said plane disposed to receive an image from said first light path and said second matrix on each said plane disposed tO receive an image from said second light path;

means for electrically connecting corresponding photosensitive elements in corresponding image locations on said first matrix on each of said planes to corresponding photosensitive elements in corresponding image locations on said second matrix on the same plane;

means for aggregating the electrical current flow of said connected photosensitive elements of both said image planes;

means for applying an electrical potential across said aggregated and connected photosensitive elements; and

means for monitoring changes in the electrical state of said circuit responsive to changes in positions of said first and second images.

8. In a base leg optical device having means for focusing images received from two viewing points, the combination comprising:

first and second light paths from each said viewing points;

means in each said light path for focusing paired images at separate focal points;

first image plane disposed at one of the focal points from each of said light paths;

a second image plane disposed at the remaining focal points from each of said light paths;

means for defining on each image plane first and second matrices of discrete electrically isolated areas;

phototransducer means at each isolated area on each of said planes, means for connecting corresponding image located electrical areas on each plane in separate electrical circuits; and

means for aggregating the flow of said separate electrical circuits on each plane.

9. The apparatus of claim 8 and including means for rotating said first and second image planes about an axis between said viewing points of said optical device.

10. A focus detector comprising in combination:

a dielectric plate having a first area for receiving a first image, a second area for receiving a second image, and a spatial interval therebetween;

a plurality of first side by side conductors on said first image area extending at least partially across said first area and electrically connected in parallel;

a plurality of second side by side conductors on said second image area extending at least partially across said second area and electrically connected in parallel and substantially parallel to said first side by side conductors;

a plurality of third conductors placed between each of said first conductors on said first area and said second conductors on said second area and spanning the spatial interval of said dielectric plate therebetween; and

a photosensitive coating applied over said dielectric plate and between said conductors.

11. The invention of claim 10 and wherein said third conductors as extending between said first and second conductors electrically connect non-corresponding portions of said image areas.

12. The apparatus according to claim 10 and wherein all said first and second side by side conductors are arcuate.

13. In combination:

a base leg optical device having means for receiving and projecting two images taken from spaced-apart positions of a field of view;

a pair of planes, each plane disposed to receive an image from said base leg optical device;

means for dividing the surface of said planes into a matrix of first and second groups of paired corresponding discrete electrically isolated areas, the areas of said first group being offset in a preselected direction with respect to the areas of said second group with respect to the field of view on each of said image planes;

phototransducer means formed at each area on each of said planes;

first means for connecting the transducer means at corresponding areas in said first group in first separate electrical circuits;

second means for connecting the transducer means at corresponding areas in second group in second separate electrical circuits; and

a bridge circuit having first and second legs for comparing first and second current flows;

first means for aggregating the current flow of said first separate electrical circuits into one leg of said bridge circuit, and second means for aggregating the current flow of said second separatE electrical circuits into the other leg of said bridge circuit and means connected to said bridge circuit for indicating the comparative current flow in said first and second legs.

14. In combination:

a range finder including a plane for receiving images of a focused object;

lens means positioned on an optical axis intermediate said plane and said focused objects, said lens means having a first segment for defining a first light path between said object and said plane and a second segment for defining a second light path between said object and said plane;

means for moving the focal plane of said lens means towards and away from said lens;

said plane having a matrix of electrical photosensitive areas thereon;

means for electrically interconnecting photosensitive elements on said plane in a series circuit;

means for applying an electrical potential across said circuit of photosensitive areas, and, means for monitoring changes in the electrical state of said series circuits.

15. Apparatus for comparing paired images of an object comprising:

first and second image planes;

means for projecting one of said paired images on one of said planes and the other of said images on the other of said planes;

a plurality of first side by side conductors on said first image plane extending at least partially across said first image plane and electrically connected in parallel;

a plurality of second side by side conductors on said second image plane extending at least partially across said second image plane and electrically connected in parallel;

a plurality of third conductors, each third conductor placed between said first conductors on said first image plane at one end and placed between said second conductors on said second image area at said second end;

a photosensitive coating applied over said dielectric plate between said conductors; and

means for measuring the aggregate current flow in said conductors.