US 4,065,778 A · Automatic rangefinder and focusing apparatus

Abstract

An automatic rangefinder and focusing apparatus is provided for use with a camera for determining the distance from an object to be photographed to the film plane of the camera and for positioning the camera's objective lens to focus an image of the object in the film plane. The apparatus comprises a photoresponsive device and a light emitter device that projects light in angularly intersecting relation to the optical axis along which light is received by a photodetector incorporated in the photoresponsive device. The light projected by the light emitter device is amplitude modulated at a frequency functionally related to the distance from the camera at which that light intersects the optical axis of the photoresponsive device. The emitted light reflected from an object located along that axis and received by the photoresponsive device produces a correspondingly modulated electric output signal that is translated into a readout of the object distance and/or into a corresponding focusing adjustment of the camera's objective lens. In a preferred embodiment, the rangefinder utilizes a plurality of light beams, each having a separate modulation frequency, which intercept three distance zones along the photodetector axis to form a zone type rangefinder and focusing apparatus. In another embodiment, two differently modulated light beams are emitted in partially overlapping relation to each other to define three distance zones. In still another embodiment, the emitter comprises movable means whereby a single light beam is swept through an angular path intersecting the photodetector axis as the modulation frequency of the beam is correspondingly changed.

Claims6

Dependent claims

An automatic rangefinding device for use in a photographic camera having an objective lens that is adjustable to different focal positions, said device comprising:

a. path defining means defining a predetermined light reception path along which light is transmitted to said rangefinding device,
b. light emitting means spaced from said reception path and adapted to emit light in angular intersecting relation to said reception path to illuminate an object located along a predetermined portion of said reception path, whereby a portion of the light emitted by said light emitting means and iluminating said object is reflected by said object along said reception path,
c. light source characterizing means for providing the light emitted by said light emitting means with a first predetermined characteristic selected to distinguish that light from light originating from other sources,
d. interception location characterizing means for providing the light emitted by said light emitting means with a second characteristic distinguishable from said first characteristic and functionally related to the location along said portion of said reception path at which such light intercepts said path,
e. photoresponsive means for receiving light transmitted along said reception path, said photoresponsive means being adapted to respond only to light having said first predetermined characteristic to produce an electrical output corresponding to said second characteristic when said photoresponsive means receives light having both of said characteristics,
f. lens focusing means for automatically adjusting the focal position of said objective lens as a function of said electrical output.

3 more elements

Dependencies are inferred from the claim text.

Automatic rangefinder and focusing apparatus

Life of this patent

Automatic rangefinder and focusing apparatus

Life of this patent

Abstract

Claims6