Distance measuring apparatus

• US 5,721,978 A
• Filed: 08/22/1996
• Issued: 02/24/1998
• Est. Priority Date: 08/23/1995
• Status: Expired due to Fees

• Current Assignee: Fuji Photo Optical Co. Ltd (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Optical Co. Ltd (Fujifilm Holdings Corporation)
• Inventors: Saito, Tatsuo
• Primary Examiner(s): ADAMS JR, RUSSELL E
• Application Number:
  US08/701,504
• Time in Patent Office: 551 Days
• Field of Search: 396/89, 396/100, 396/111, 396/112, 396/113, 396/114, 396/115, 396/116, 396/117
• US Class Current: 396/100
• 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

In a distance measuring apparatus, a light-detecting portion in a trigonometric distance measuring apparatus using a passive method is also used as a light-detecting portion for photometry processing. Thus, the luminance range for distance measurement is widened. The distance measuring apparatus includes two light-detecting portions arranged in correspondence with two optical systems. Correction filters for luminous efficacy correction is arranged in the optical paths of each optical system covering halves of the corresponding light-detecting portions.

Claims

1. A distance measuring apparatus using a passive method for receiving light reflected by an object to measure distance to the object comprising:

two optical systems for respectively condensing the light reflected by the object;

two light-receiving means respectively disposed in correspondence with said two optical systems to detect optical images condensed by said corresponding optical systems, each light-receiving means having first and second light-receiving portions;

two correction filters for correcting respective sensitivities of said second light-receiving portions;

detecting means for detecting luminance of the object on the basis of the optical images of the object received by said two second light-receiving portions;

determining means for determining whether the luminance detected by said detecting means is high or low;

first distance measuring means for measuring the distance to the object on the basis of the optical images received by said two second light-receiving portions when said determining means determines that the luminance is high; and

second distance measuring means for measuring the distance to the object on the basis of the optical images received by said two first light-receiving portions when said determining means determines that the luminance is low.

2. An apparatus according to claim 1, wherein said detecting means comprises:

first means for counting a response time of each of said second light-receiving portions at which an integrated value output from said second light-receiving portion reaches a predetermined reference level earlier; and

second means for specifying the luminance of the object on the basis of the response time counted by said first means.

3. An apparatus according to claim 1, wherein said detecting means further comprises:

a plurality of third means for outputting detection signals when integrated values output from said respective second light-receiving portions exceed a predetermined reference level, said third means being arranged in correspondence with said respective second light-receiving portions;

fourth means for respectively counting response time intervals until the detection signals are output from said individual third means; and

fifth means for specifying the luminance of the object on the basis of data of the response time intervals counted by said fourth means.

4. An apparatus according to claim 3, wherein said first distance measuring means executes distance measurement calculation on the basis of the data of the response time intervals having been counted by said fourth means when said determining means determines that the luminance specified by said fifth means is high.

5. An apparatus according to claim 1, wherein said first light-receiving portion is a first photosensor array including a plurality of photosensors, and said second light-receiving portion is a second photosensor array including a plurality of photosensors.

6. An apparatus according to claim 1, wherein said first and second light-receiving portions are constituted by a plurality of CCDs.

7. An apparatus according to claim 1, wherein said distance measuring apparatus performs averaged overall light reading on the basis of detection results of said first and second light-receiving portions.

8. An apparatus according to claim 1, wherein said distance measuring apparatus performs center-weighted light reading on the basis of detection results of said first and second light-receiving portions.

9. A distance measuring apparatus using a passive method for detecting light reflected from an object to measure distance to the object, the apparatus comprising:

two optical systems for respectively condensing light reflected from an object;

two light detecting means respectively disposed in correspondence with said two optical systems for detecting optical images condensed by said corresponding optical systems, each light detecting means having first and second light detecting portions;

two correction filters for correcting respective sensitivities of said light detecting portions, respectively disposed between said two optical systems and said two light detecting means;

detecting means for detecting luminance of the object from the optical images detected by said two second light detecting portions;

determining means for determining whether the luminance detected by said two second light detecting portions is larger than a reference level;

first distance measuring means for measuring the distance to the object from the optical images detected by said two second light detecting portions when said determining means determines that the luminance exceeds the reference level; and

second distance measuring means for measuring the distance to the object from the optical images detected by said two first light detecting portions when said determining means determines that the luminance does not exceed the reference level.

10. The apparatus according to claim 9 wherein said detecting means comprises:

counting means for counting response time until an output from each of said second light detecting portions reaches the reference level; and

means for specifying the luminance of the object according to the response time.

11. The apparatus according to claim 9 wherein said detecting means comprises:

a plurality of output means for outputting detection signals when outputs from said respective second light detecting potions exceed the reference level, said output means being arranged in correspondence with said second light detecting portions;

counting means for respectively counting response times until the detection signals are output by respective output means; and

means for specifying the luminance of the object according to the response time intervals.

12. The apparatus according to claim 11 wherein said first distance measuring means calculates distance according to the response time intervals when said determining means determines that the luminance exceeds the reference level.