AUTOMATIC RANGEFINDER MEANS

• US 3,617,128 A
• Filed: 10/28/1968
• Issued: 11/02/1971
• Est. Priority Date: 10/28/1968
• Status: Expired due to Term

• Current Assignee: Donald M. Harvey
• Original Assignee: Donald M. Harvey
• Inventors: Harvey, Donald M.
• Primary Examiner(s): Bennett, Jr., Rodney D.
• Assistant Examiner(s): Baxter, Joseph G.
• Application Number:
  US04/771,209
• Time in Patent Office: 1,100 Days
• Field of Search: 356/152,4
• US Class Current: 356/4.03
• CPC Class Codes: G02B 7/32 using active means, e.g. light emitter including both an active and a passive focus detecting device G02B7/285; using ultrasound G02B7/40

Abstract

This disclosure relates to an automatic rangefinder utilizing refracted light from a subject to ascertain range distance. Light is transmitted toward the subject, and the refracted light is received by an optical system suitably masked so as to admit the refracted light only around peripheral portions. Photosensitive materials are arranged at the image plane of the optical system, the photosensitive materials having a predetermined geometrical configuration wherein predetermined loci are functions of range distance. The discrete locus delineated by the refracted light at the image plane is then identified to determine range distance.

Claims

1. In a rangefinder, the combination comprising:

a. means for projecting a beam of light to an object to illuminate a predetermined area of the surface of the object;

b. a lens for forming an image of the illuminated object area in a plane, the location of the image in the plane being a function of the distance of the object from the plane;

c. a plurality of photosensitive means, each of said photosensitive means being disposed in a predetermined location in the plane and having a parameter which varies as a function of incident illumination; and

d. means coupled to said plurality of photosensitive means and responsive to variations in the parameters thereof to determine the location of the image.

2. In a rangefinder, the combination comprising:

a. means for projecting a beam of light to an object to illuminate a predetermined area of the surface of the object;

b. a lens for forming an image of the illuminated predetermined object area in a plane, said lens being adapted to form the image having at least one selected portion of greater brightness than the remaining portions thereof, the location of the selected image portion in the plane being a function of the distance of the object from the plane;

c. a plurality of photosensitive means, each of said photosensitive means being disposed in a predetermined location in the plane and having a parameter which varies as a function of incident illumination; and

d. means coupled to said plurality of photosensitive means and responsive to variations in the parameters thereof to determine the location of the image.

3. In a rangefinder, the combination comprising:

a. means for projecting a beam of light to an object to illuminate a predetermined area of the surface of the object;

b. a lens for forming an image of the illuminated predetermined object area in a plane, said lens being adapted to form the image to have at least one selected portion having greater brightness than the remaining portions thereof, the location of the selected image portion in the plane being a function of the distance of the object from the plane;

c. a plurality of photosensitive means, each of said photosensitive means having a parameter which varies as a function of incident illumination and being disposed in a predetermined location in the plane and adapted to receive illumination from the selected image portion when the object is disposed within a particular range of distances from the plane; and

e. means coupled to said plurality of photosensitive means and responsive to variations in the parameters of said plurality of said photosensitive means to determine the particular range of distances from the plane wherein the object is disposed.

4. The invention as set forth in claim 3 wherein said lens is a converging lens and includes an annular portion for receiving light reflected from the object to form the image.

5. In a rangefinder, the combination comprising:

a. a lens defining an optical axis;

b. a source of light;

c. means cooperatively disposed with respect to said light source for projecting a beam of light from said source to an object disposed along said optical axis to illuminate a predetermined area of the surface of the object;

d. said lens being adapted to form an image of the illuminated predetermined object area in a plane disposed a fixed distance substantially equal to or greater than the focal length of said lens from said lens, said lens being adapted to foRm the image to have at least one selected portion having greater brightness than the remaining portion thereof, the location of the selected image portion in the plane being a function of the distance of the object from the plane;

e. a plurality of photosensitive means, each of said photosensitive means having a parameter which varies as a function of incident illumination and being disposed in a predetermined location in the plane and adapted to receive light from the selected image portion when the object is disposed within a particular range of distances from the plane; and

f. means coupled to said plurality of photosensitive means and responsive to variations in the parameters thereof to determine the particular range of distances wherein the object is disposed.

6. The invention as set forth in claim 5 wherein said plurality of photosensitive means comprises a plurality of photoresponsive cells, each being formed in the shape of a concentric ring and each associated with a different particular range of distances from the plane.

7. The invention as set forth in claim 6 wherein said distance signal producing means comprises means for determining which of said photoresponsive cells receives the greatest incident illumination.

8. The invention as set forth in claim 5 wherein said lens comprises a spherical lens effectively masked so as to admit light only around the peripheral portions thereof.

9. The invention as set forth in claim 5 wherein said light source includes means for modulating said light at a predetermined frequency.

10. For use in a photographic apparatus adapted to focus a first image of an object in a primary image plane by varying the relative distance between an objective lens and the object, the combination comprising:

a. a second lens defining an optical axis;

b. a source of light;

c. means cooperatively disposed with respect to said light source for projecting a beam of light from said source along said optical axis to illuminate a predetermined area of the object surface;

d. said second lens being adapted to form a second image of the illuminated predetermined object area in a second plane disposed a fixed distance from said second lens substantially equal to or greater than the focal length of said second lens, said second lens being adapted to form the second image to have at least one selected portion having greater brightness than the remaining portions thereof, the location of the selected second image portion in the second plane being a function of the distance of the object from the second plane;

e. a plurality of photosensitive means each having a parameter which varies as a function of incident illumination and each being disposed in a predetermined location in the second plane and adapted to receive illumination from the selected portion of the second image when the object is disposed within a particular range of distances from the second plane;

f. means coupled to said plurality of photosensitive means and responsive to variations in the parameters thereof to produce a signal representative of the particular range of distances wherein the object is disposed; and

g. means coupled to the objective lens and responsive to said signal to position the objective lens to focus the first image of the object in the primary image plane.

11. The invention as set forth in claim 10 wherein said lens comprises a spherical lens effectively masked so as to admit light only around the peripheral portions thereof.

12. The invention as set forth in claim 10 wherein said light source includes means for modulating said light at a predetermined frequency.