Distance-measuring apparatus

• US 5,426,482 A
• Filed: 01/12/1994
• Issued: 06/20/1995
• Est. Priority Date: 01/14/1993
• Status: Expired due to Fees

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Tsuru, Hiroyuki
• Primary Examiner(s): ADAMS JR, RUSSELL E
• Application Number:
  US08/180,322
• Time in Patent Office: 524 Days
• Field of Search: 354/403, 354/195.12, 250/201.4, 250/201.5, 250/201.6
• US Class Current: 396/123
• CPC Class Codes: G01S 17/46 Indirect determination of position data
• CPC Class Codes: G01S 17/88 Lidar systems specially adapted for specific applications
• CPC Class Codes: G01S 7/493 Extracting wanted echo signals
• 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

A distance-measuring apparatus comprises a light emitting device for emitting a beam toward a plurality of portions in a field, a light receiving device for receiving a reflection beam from an object located at each of the plurality of portions and outputting a receiving signal according thereto, a selecting device for searching out a region where the receiving signal exceeds a predetermined value out of the plurality of portions and selecting an aimed portion for distance measurement from the searched-out region where the receiving signal exceeds the predetermined value, and a measuring device for measuring an object distance based on a receiving signal from the aimed portion for distance measurement.

Claims

1. A distance-measuring apparatus comprising:

a light emitter for emitting a beam of light toward a plurality of portions in a field;

a light receiver for receiving a reflection beam of light from an object located at each of said plurality of portions and outputting a corresponding signal having an intensity dependent upon the amount of received light;

a selector responsive to said signals for selecting a portion in said field corresponding to a signal having an intensity that exceeds a predetermined value; and

a measuring device for measuring distance to an object in the selected portion.

2. A distance-measuring apparatus according to claim 1, wherein said predetermined value is a value obtained by subtracting a predetermined fixed value from a maximum value of the signals corresponding to said plurality of portions.

3. A distance-measuring apparatus according to claim 1, wherein if signals corresponding to a plurality of mutually adjacent portions have intensities that exceed said predetermined value, a portion located at the center of the mutually adjacent portions as selected by said selector.

4. A distance-measuring apparatus according to claim 1, wherein said selector comprises a storage portion for storing information designating mutually adjacent portions in said field corresponding to signals having intensities that exceed said predetermined value, and a selecting portion which, when the number of said mutually adjacent portions reaches a predetermined number, selects a portion located at the center of the predetermined number.

5. A distance-measuring apparatus according to claim 1, further comprising:

a driver for rotatively driving said light emitter so that said beam is emitted toward said plurality of portions; and

a controller for determining a range of rotational driving of said light emitter in accordance with a photographing field angle.

6. A distance-measuring apparatus according to claim 5, wherein said controller decreases said range of rotational driving as said photographing field angle becomes smaller.

7. A distance-measuring apparatus comprising:

a light emitting element for emitting a beam of light toward a plurality of portions in a field;

a light receiving element for receiving light reflected by an object located at each of said plurality of portions and outputting a corresponding signal having an intensity dependent upon the amount of received light;

a selector for selecting a portion located at the center of portions corresponding to signals having intensities that exceed a predetermined value; and

a calculator for calculating distance to an object located at the selected portion.