Range finder

• US 4,441,810 A
• Filed: 07/09/1981
• Issued: 04/10/1984
• Est. Priority Date: 07/15/1980
• Status: Expired due to Term

• Current Assignee: Konishiroku Photo Industry Co., Ltd.
• Original Assignee: Konishiroku Photo Industry Co., Ltd.
• Inventors: Hoshino, Yasushi, Takahashi, Toshiaki, Momose, Haruhiko
• Primary Examiner(s): Wilbur, Maynard R.
• Assistant Examiner(s): Gordon, M. R.
• Application Number:
  US06/281,890
• Time in Patent Office: 1,006 Days
• Field of Search: 356/1, 356/4, 354/25 R, 354/25 P
• US Class Current: 356/3.15
• CPC Class Codes: G01C 3/10 using a parallactic triangle with variable angles and a base of fixed length in the observation station, e.g. in the instrument
• CPC Class Codes: G01S 17/46 Indirect determination of position data

Abstract

A range finder for measuring the distance of an object to be measured by the steps of radiating the spot light to the object, forming an image of the reflected ray of light by image forming means and measuring the distance of the object from the output of an element which is disposed at a position substantially corresponding to the image forming position and of which output varies in accordance with the light-receiving position on the light-receiving surface. PSD are used as the element. A focussing detector which includes a semiconductor position detection element PSD placed at a position corresponding to the film surface in a camera or the like and detects the focussing state on the basis of the electric output from the semiconductor position detection element PSD. A focussing detector which comprises image forming means for forming the image of an object; a PSD disposed in such an arrangement that the light-receiving surface thereof is eccentric with respect to the optical axis of an optical system including the image forming means and disposed at the back of the image forming means; and an operation circuit detecting the extreme values of the output of the PSD and producing a focussing signal.

Claims

1. A range finder comprising:

(a) image forming means disposed fixedly with respect to an object;

(b) a semiconductor position detection element disposed at a position substantially corresponding to the image forming position of said image forming means;

(c) a semi-transparent mirror disposed between said image forming means and said object;

(d) a moving relecting mirror disposed so as to be spaced apart by a length of a basic line from said semi-transparent mirror;

(e) driving means for relatively moving an optical image formed by said moving reflecting mirror, said semi-transparent mirror and said image forming means on said semiconductor position detection element with respect to an optical image formed by said image forming means on said semiconductor position detection element through said semi-transparent reflecting mirror;

(f) light-interception means for temporarily intercepting a ray of light incident from said reflecting mirror to said semiconductor position detection element and memory means for temporarily storing only a signal representing an incident ray of light emanating from said object through said semi-transparent reflecting mirror during the interim while said ray of light from said reflecting mirror is intercepted; and

(g) an operation circuit for operating on the output signals of said semiconductor position detection element and said memory means for producing a distance signal representing the distance between said object and said image forming position of said image forming means.

2. The range finder as defined in claim 1 which uses a position sensitive detector in said semiconductor position detection element.

3. A range finder comprising:

(a) a first position detection element providing an output signal and comprising first image forming means disposed fixedly with respect to an object and a semiconductor position sensitive detector placed at a position substantially corresponding to the image forming position of said first image forming means;

(b) a second position detection element providing an output signal and comprising second image forming means and a semiconductor position sensitive detector placed at a position substantially corresponding to the image forming position of said second image forming means;

(c) driving means for relatively moving said second image forming means of said second position detection element; and

(d) an operation circuit for operating on the output of said first and second position detection elements and producing a distance signal representing the distance between said object and said image forming position of said first image forming means.

4. A range finder comprising:

(a) a light source to radiate light to an object;

(b) an image forming means to form an image of the reflected ray of light from said object;

(c) a position sensitive detector having a light-receiving surface disposed at a position substantially corresponding to the image forming position of said image forming means and an output signal of which varies in accordance with the light-receiving position of said image on said light-receiving surface; and

(d) position detection processing circuit means for receiving said output signal to provide an electric signal corresponding to the distance between said object and said image forming position of said image forming means.

5. A range finder comprising:

image forming means for forming the image of an object;

a position sensitive detector for providing output signals and disposed in such an arrangement that the light-receiving surface thereof, which is partially masked, is eccentric with respect to the optical axis of an optical system including another image forming means, including a semi-transparent mirror, and disposed at the back of said last-recited image forming means; and

an operation circuit for detecting the extreme values of the output signals of said position sensitive detector and producing a focusing signal.

6. A range finder comprising:

a lens for forming the image of an object;

a semi-transparent mirror behind said lens, a split image prism juxtaposed at the back of said lens for receiving an image reflected from said semi-transparent mirror;

a pair of semiconductor position detection elements so disposed at the back of said split image prism as to correspond in position to the split images from said prism and for providing output signals representing said split images thereto; and

an operation circuit for operating on the output signals of said semiconductor position detection elements and producing a focusing signal.