Apparatus for detecting distance to an object

• US 4,690,549 A
• Filed: 02/03/1986
• Issued: 09/01/1987
• Est. Priority Date: 10/26/1981
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Nakada, Yasuo
• Primary Examiner(s): Buczinski, Stephen C.
• Assistant Examiner(s): Issing, Gregory C.
• Application Number:
  US06/824,946
• Time in Patent Office: 575 Days
• Field of Search: 356/4, 354/407, 354/408, 354/402, 250/201
• US Class Current: 356/4.04
• CPC Class Codes: G01C 3/32 by focusing the object, e.g. on a ground glass screen

Abstract

An apparatus for detecting distance to an object is disclosed, which includes a taking or imaging lens for collecting a light from an object, a first lens device for forming the light from the object and through the taking lens to a parallel light bundle when the object is positioned at the focal point of the taking lens, a second lens device for focussing the light through the first lens device, a light sensing device for receiving the light through the second lens device, a separating device for separating the light from the first lens device into at least two bundles of light which are shifted perpendicularly to the optical axis of the second lens device, and a detecting device for detecting the displacement of the multiple images on the light sensing device caused by the separated bundles of light by the separating device when the object is not at the focal point of the taking lens and for generating an output varying with the distance to the object.

Claims

1. Apparatus for detecting the distance to an object comprising:

an imaging lens for focussing light from the object;

first lens means for forming the light from the object and passing through said imaging lens into a plurality of light rays which are parallel when the object is disposed at the focal point of said imaging lens and which converge and diverge an amount depending on the direction and amount of displacement of the object from the focal point of said imaging lens;

separating means for separating said light rays from said first lens means into at least two bundles of light;

second lens means for forming each said bundle of light into a separate image at a respective location depending on the amount of convergence and divergence of said light rays;

light sensing means for sensing said locations of said images; and

detecting means for detecting said locations of said images on said light sensing means and for generating an output varying with the displacement of said images from the locations thereof when the object is at the focal point of said imaging lens.

2. Apparatus according to claim 1;

wherein said separating means includes a half mirror for reflecting a part of the light from said first lens means to said second lens means and for transmitting the rest of the light, and a full mirror for reflecting said rest of the light to said second lens means.

3. Apparatus according to claim 2;

wherein said second lens means includes separate lenses one of which is disposed for receiving the reflected light from said half mirror and the other of which is disposed for receiving the reflected light from said full mirror.

4. Apparatus according to claim 1;

wherein said separating means includes a first full mirror for reflecting a first portion of the light from said first lens means, a second full mirror for reflecting the light from said first full mirror to form a first light bundle for forming by said second lens means into a first image, a third full mirror for reflecting a second portion of the light from said first lens, and a fourth full mirror for reflecting the light from said third full mirror to form a second light bundle for forming by said second lens means into a second image shifted perpendicularly to the optical axis of said second lens relative to said first image.

5. Apparatus according to claim 1;

wherein said separating means includes a mirror having first and second reflecting faces displaced relative to each other in the direction of the optical axis of said first lens means, and said light sensing means includes a cylindrical lens for directing the light from said first and second reflecting faces to first and second photo detectors, respectively, comprising said detecting means.

6. Apparatus according to claim 1;

wherein said separating means includes a transparent glass panel having an entrance face and an exit face, said entrance face operating as a half mirror for reflecting a part of the light from said first lens means and refracting the rest of said light toward said exit face which further refracts said rest of the light.

7. Apparatus according to claim 1;

wherein said light sensing means includes photo detector means comprising a plurality of light sensors and a fly-eye-lens arranged at the focal plane of said second lens means and having a plurality of lens elements for cooperating with said light sensors to provide images on said light sensors.

8. Apparatus according to claim 7;

wherein each said light sensor includes a first and second light sensing element and has one of said lens elements associated therewith and each said first light sensing element detects an image resulting from said first bundle of light and each said second light sensing element detects an image resulting from said second bundle of light.

9. The apparatus of claim 1;

wherein said second lens means has an optical axis; and

wherein said separating means shifts at least one said bundles of light perpendicular to said optical axis.

10. Apparatus according to claim 1;

further comprising focussing means for adjusting the focal length of said imaging lens, said focussing means being operable in response to the output of said detecting means to adjust said focal length substantially to coincide with the distance to the object.

11. Apparatus as in claim 10, wherein:

said detecting means comprises a plurality of photosensors for detecting the locations of images focussed on said light sensing means; and

said focussing means comprises a focal point detection circuit for providing a driving signal in response to the detection of the locations of said images by said photosensors, said driving signal being indicative of the displacement of said images from their locations when the object is at the focal point of the imaging lens, and drive means for moving said imaging lens in response to said driving signal.

12. An automatic focusing camera comprising:

an imaging lens for focusing light from an object a predetermined distance from said imaging lens, said imaging lens having an adjustable focal length;

first means for forming the light from the object and passing through said imaging lens into a plurality of light rays which are parallel when the object is disposed at the focal point of said imaging lens and which converge and diverge an amount depending on the direction and amount of displacement of the object from the focal point of said imaging lens;

separating means for separating said light rays from said first lens means into at least two bundles of light;

second lens means for forming said bundles of light into respective, separate images at respective locations depending on the amount of diversions and conversions of said light rays;

light sensing means for sensing said location of said images;

detecting means for detecting said locations of said images on said light sensing means and for generating an output varying with the displacement of said images from the locations thereof when the object is at the focal point of said imaging lens; and

focussing means responsive to said output for adjusting the focal length of said imaging lens to coincide substantially with the distance to said object from said imaging lens.

13. A camera according to claim 12;

further comprising an optical view-finding system in which the light from said imaging lens is deflected for viewing.

14. A camera according to claim 12;

further comprising a zoom lens including said imaging lens and said first lens means.

15. A camera according to claim 12;

further comprising means for recording movements of the object.

16. The apparatus of claim 12;

wherein said second lens means has an optical axis; and

wherein said separating means shifts at least one of said bundles of light perpendicular to said optical axis.

17. A method for detecting the distance to an object, comprising the steps of:

passing the light from the object through an imaging lens;

forming the light from the imaging lens into a plurality of light rays which are parallel when the object is positioned at the focal point of the imaging lens and which converge and converge an amount depending on the direction and amount of displacement of the object from the focal point of the imaging lens;

separating said plurality of light rays into a plurality of light bundles;

forming said bundles into respective, separate images at respective locations depending on the amount of diversions and conversions of said light rays; and

detecting the amount of displacement of said images from the locations thereof when the object is at the focal point of said imaging lens.

18. The method according to claim 17;

further comprising the steps of;

providing an output signal indicative of said amount of displacement; and

adjusting the focal length of said imaging lens in response to said output signal to coincide with said predetermined distance to the object.

19. The method of claim 17;

wherein said step of forming said light bundles is performed by passing said light bundles through a lens means having an optical axis; and

said step of separating said plurality of light rays includes the step of shifting at least one of said light bundles perpendicular to said optical axis.