US 4,291,223 A · Distance detecting device

Abstract

A distance detecting device comprising radiation projecting means for projecting a radiation beam; radiation sensing means which is disposed away from the radiation projecting means with a given length and is arranged to receive a reflected radiation beam coming from an object whose distance is to be detected as the radiation beam is projected from the projecting means; and movable means for relatively varying the incident condition of the projected radiation beam onto the sensing means. The distance to the object is found either by the position of the movable means or by the amount of displacement thereof which occurs at a time point at which the sensing means optimally receive the reflected radiation beam coming from the object in the process of relatively varying the incident condition of the projected radiation beam onto the sensing means. In the incident condition varying process, the output signal of the sensing means and a delayed signal which is obtained by delaying the output signal a predetermined period of time are compared with each other to detect a time point at which the output signal of the sensing means has reached its peak level and, accordingly, to detect when the sensing means optimally receive the reflected radiation beam coming from the object.

Claims30

Dependent claims

A distance detecting device for detecting a distance between an object and the device, comprising:

(A) means for projecting a radiation to the object;
(B) means for sensing the radiation reflected by and coming from the object, said sensing means producing an output signal indicative of the intensity of the received radiation;
(C) means for relatively changing an incident position of the projected radiation to said sensing means, said changing means being shiftable from a predetermined position to change said incident position of the projected radiation to the sensing means relatively, each shifting position of the changing means being indicative of the distance between the object and the device;
and
(D) circuit means responsive to the output signal of said sensing means, said circuit means including:
(D-1) delay means receiving the output signal of the sensing means and providing a delayed signal having a predetermined delay relative to the output signal of the sensing means, and
(D-2) means for detecting the coincidence between the output signal of the sensing means and the delayed signal provided by said delay means, said detecting means producing an output signal indicative of the coincidence of said two signals when detecting the coincidence of the two signals;
thereby the distance between the object and the device is indicated by the shifting position of the changing means at the time when the detecting means produces the output signal indicative of the coincidence of the two signals.

5 more elements

An automatic focusing system comprising:

(A) objective lens means to be focused on an object, said lens means having an optical axis and shiftable along the axis;
(B) means for shifting said lens means from a predetermined position in a predetermined direction along the optical axis;
(C) means for projecting a radiation to the object;
(D) means for sensing the radiation reflected by and coming from the object, said sensing means producing an output signal indicative of intensity of the received radiation;
(E) means for relatively changing an incident position of the projected radiation to said sensing means, said changing means being operatively associated with said lens means and shiftable from a predetermined position in a predetermined direction, in response to the shifting of the lens means by said shifting means, to change said incident position of the projection radiation to the sensing means relatively;
(F) circuit means responsive to the output signal of said sensing means, said circuit means including:
(F-1) delay means receiving the output signal of the sensing means and providing a delayed signal having a predetermined delay relative to the output signal of the sensing means, and
(F-2) means for detecting the coincidence between the output signal of the sensing means and the delayed signal provided by said delay means, said detecting means producing an output signal indicative of the coincidence of said two signals when detecting the coincidence of the two signals;
and
(G) means for arresting the shifting of said lens means in response to the output signal of said detecting means.

7 more elements

Dependencies are inferred from the claim text.

Distance detecting device

Life of this patent

Distance detecting device

Life of this patent

Abstract

Claims30