Range detecting method and apparatus

• US 4,189,232 A
• Filed: 01/05/1978
• Issued: 02/19/1980
• Est. Priority Date: 01/06/1977
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Niwa, Yukichi, Tsuda, Shin, Asano, Noriyuki, Owada, Mitsutoshi, Yamagata, Takaaki
• Primary Examiner(s): Buczinski, S. C.
• Application Number:
  US05/867,339
• Time in Patent Office: 775 Days
• Field of Search: 356/1, 356/4, 354/25, 250/201, 250/204
• US Class Current: 356/3.15
• CPC Class Codes: G02B 7/30 using parallactic triangle with a base line

Abstract

A range detecting method and apparatus of a construction, in which first and second images of an object to be formed by a range finding optical system with a relative positional parallax corresponding to the object distance are scanned purely electrically by the use of one or more photo-sensor arrays, then analog image element signals concerning these first and second images obtained at this time are sequentially converted into two-value signals, after which the two-value signals are stored, as inputs, in first and second digital storing device where the coincidence and non-coincidence of these digital image scanning signals stored in these first and second storing devices are detected by means of a coincidence detecting device, while one of these image scanning signals are relatively shifted bit by bit with respect to other image scanning signals, and the shift bit quantities required until the digital image scanning signals of the same bit numbers concerning these first and second images may become optimumly coincided, thereby finding out the object distance from the shift bit quantities.

Claims

1. A method of detecting a range of an object comprising the steps of:

(a) deriving first and second images of said object along different sight lines;

(b) electrically sensing said first and second images to produce an electrical analog signal for each image element of said first and second images;

(c) quantizing said electrical analog signal to produce quantized data for each image element of the first and second images;

(d) storing the quantized data on N successive elements of the first image and successively storing, on one set-by-set basis, the quantized data on each of a plurality of different sets of N successive elements of the second image;

(e) comparing the stored quantized data on said set of the N successive elements of the second image with the stored quantized data on the N successive elements of the first image at every time the quantized data on a set of the N successive elements of the second image are stored;

(f) detecting, through said comparison process, a set of the N successive elements of the second image which can be regarded as being substantially identical with the N successive elements of the first image; and

(g) determining the range of the object on the basis of a location, within the second image, of said set of the N successive elements of the second image which has been regarded as being substantially identical with the N successive elements of the first image through said detection process.

3. A method according to claim 1, wherein said range determination process comprises the step of storing, at every time the quantized data on a set of the N successive elements of the second image are stored, a location, within the second image, of said set of the N successive elements of the second image whose quantized data are stored.

4. A method according to claim 3, wherein said range determination process further comprises the step of reading out the stored data on the location at the instant when a set of the N successive elements of the second image which can be regarded as being substantially identical with the N successive elements of the first image have been detected.

5. A method according to claim 4, wherein said location storing process includes counting of address number, within the second image, of each set of the N successive elements of the second image, the quantized data of which are stored;

and said read-out process includes reading-out of the counted address number at the instant when a set of the N successive elements of the second image which can be regarded as being substantially identical with the N successive elements of the first image have been detected.

6. A method according to claim 4, wherein said comparison process includes the step of searching of match data in the stored quantized data on a set of the N successive elements of the second image with respect to the stored quanitzed data on the N successive elements of the first image.

7. A method according to claim 6, wherein said detection process comprises the step of counting the number of searched match data in each of said plurality of sets of the N successive elements of the second image.

8. A method according to claim 7, wherein said detection process further comprises the step of detecting whether the counted number of the match data has reached a predetermined number, whereby a set of the N successive elements of the second image, the counted number of the match data of which reached said predetermined number, is regarded as the set which is substantially identical with the N successive elements of the first image.

9. A method according to claim 7, wherein said detection process further comprises the step of detecting the largest number of the match data, whereby a set of the N successive elements of the second image, the number of the match data of which have become the largest, is regarded as the set which is substantially identical with the N successive elements of the first image.

10. A method according to claim 4, wherein said quantization process comprises the steps of:

detecting the maximum level in the electrical analog signals on the elements of the first image;

setting a reference level on the basis of the detected maximum level; and

comparing said electrical analog signal on each image element of the first and second images with respect to the set reference level.

11. A method according to claim 10, wherein the process for setting said reference level includes setting of a level lower than said detected maximum level.

2. An apparatus for detecting the range of an object comprising:

(a) optical means arranged to form first and second images of said object along different sight lines;

(b) image sensing means arranged to receive said first and second images to produce an electrical analog signal for each image element of said first and second images;

(c) quantization means for quantizing said electrical analog signal to produce quantized data for each image element of said first and second images;

(d) data storing means adapted to store the quantized data on N successive elements of said first image and to successively store, on one set-by-set basis, the quantized data on a plurality of different sets of N successive elements of said second image;

(e) comparison means for comparing the stored quantized data on said set of the N successive elements of the second image with the stored quanitzed data on the N successive elements of the first image at every time the quantized data on a set of the N successive elements of the second image are stored in said data storing means;

(f) detection means for detecting, based on an output from said comparison means, a set of the N successive elements of the second image which can be regarded as being substantially identical with the N successive elements of the first image; and

(g) range determination means for determining the range of the object on the basis of a location, within the second image, of said set of the N successive elements of the second image which has been regarded as being substantially identical with the N successive elements of the first image by said detection means.

12. An apparatus according to claim 2, wherein said range determination means comprises location storing means for storing, at every time the quantized data on a set of the N successive elements of the second image are stored in said data storing means, a location, within the second image, of said set of N successive elements of the second image whose quantized data are stored.

13. An apparatus according to claim 12, wherein said range determination means further comprises read-out means for reading out the stored data on the location from said location storing means, at the instant when a set of the N successive elements of the second image which can be regarded as being substantially identical with the N successive elements of the first image have been detected by said detection means, said read-out means being coupled to said location storing means and said detection means.

14. An apparatus according to claim 13, wherein said location storing means is a counting circuit which counts address number, within the second image, of each set of the N successive elements of the second image, the quantized data of which are stored in said data storing means;

and said read-out means is a read-out circuit which reads out from the counting circuit the address number counted by said counting circuit at the instant when said detection means detects a set of the N successive elements of the second image which can be regarded as being substantially identical with the N successive elements of the first image, and which is coupled to said detection means and said counting circuit.

15. An apparatus according to claim 13, wherein said comparison means includes a match detecting circuit for detecting match data in the stored quantized data on a set of the N successive elements of the second image with respect to the stored quantized data on the N successive elements of the first image, said match detecting circuit being coupled to said data storing means.

16. An apparatus according to claim 15, wherein said detection means comprises a match counting circuit for counting the number of match data detected by said match detecting circuit, said match counting circuit being coupled to said match detecting circuit.

17. An apparatus according to claim 16, wherein said detection means further comprises a match count detecting circuit for detecting whether the match count of said match counting circuit has reached a predetermined count, said match count detecting circuit being coupled to said match counting circuit and producing a coincided signal when the match count of the match counting circuit reached said predetermined count, and said read-out means being coupled to said match count detecting circuit to read out from said location storing means the stored data on the location in response to said coincided signal, whereby a set of the N successive elements of the second image, the number of the match data of which has reached said predetermined number, is regarded as the set which is substantially identical with the N successive elements of the first image.

18. An apparatus according to claim 16, wherein said detection means further comprises a match count comparing circuit for detecting the largest match count of said match counting circuit, said match count comparing circuit being coupled to said match counting circuit and providing an electrical signal at every time the match count of the match counting circuit increases, and said read-out means being coupled to said match count comparing circuit and reading out from said location storing means the stored data on the location at every time said electrical signal is provided, whereby a set of the N successive elements of the second image, the number of the match data of which have become the largest, is regarded as the set which is substantially identical with the N successive elements of the first image.

19. An apparatus according to claim 2, wherein said quantization means comprises:

first circuit means for detecting the maximum level in the electrical analog signals on the elements of the first image produced from said image sensing means;

second circuit means for setting a reference level on the basis of the detected maximum level detected by said first circuit means, said second circuit means being coupled to said first means; and

third circuit means for comparing said electrical analog signal on each image element of said first and second images produced from said image sensing means with respect to said reference level set by said second circuit means, said third circuit means being coupled to said second circuit means; and

wherein said data storing means is coupled to said third circuit means to store therein the output from said third circuit means.

20. An apparatus according to claim 19, wherein said second circuit means comprises electrical means for setting a level lower than the maximum level detected by said first circuit means.

21. An apparatus according to claim 2, wherein said data storing means comprises:

a first shift register having N storing locations and adapted to store the quantized data on the N successive elements of said first image; and

a second shift register having N storing locations and adapted to successively store, on one set-by-set basis, the quantized data on said plurality of sets of the N successive elements of said second image; and

wherein said comparison means is coupled to said first and second shift registers.

22. An apparatus according to claim 21, wherein said first and second shift registers are serial-in-parallel-our type shift registers.

23. An apparatus according to claim 21, wherein said first and second shift registers are serial-in-serial-out recirculation type shift registers.

24. An apparatus according to claim 2, wherein said optical means comprises:

first optical channel means for focussing said first image onto a first portion of said image sensing means; and

second optical channel means for focussing said second image onto a second portion of said image sensing means, said second optical channel means being disposed away from said first optical channel means so that said first and second images are derived along different sight lines.

25. An apparatus according to claim 24, wherein said image sensing means comprises a first array of photosensors for receiving said first image and a second array of photo-sensors for receiving said second image.

26. An apparatus according to claim 25, wherein said first array includes first number of photo-sensors, and said second array includes second number of photo-sensors which are more in number than the photo-sensors included in said first array.

27. An apparatus according to claim 24, wherein said image sensing means comprises an array of photo-sensors for receiving both of said first and second images.

28. An apparatus according to claim 27, wherein said array of photo-sensors has:

a first region which includes first number of photo-sensors to be used for receiving said first image; and

a second region which includes second number of photo-sensors which is more in number than the photo-sensors included in said first region, and which are used for receiving said second image.

29. An apparatus according to claim 2, wherein said image sensing means has a plurality of image sensing elements for sensing the image elements of said first and second images and producing said electrical analog signal for each image element of the first and second images;

and said apparatus further comprises driver circuit means for electrically driving each of said image sensing elements of the image sensing means, said driver circuit means being coupled to the image sensing means and providing intermittent start pulses and intermittent drive pulses.

30. An apparatus according to claim 29, further comprising adjustment circuit means for adjusting the light receiving time of each of said image sensing elements of the image sensing means, said adjustment circuit means being capable of responding to the electrical analog signal produced from said image sensing means;

being coupled to said driver circuit means; and

adjusting the light receiving time of each of said image sensing element by adjusting the time interval of said start pulses to be provided to the image sensing means from the driver circuit means in accordance with the level of said electrical analog signal.

31. An apparatus according to claim 30, wherein said adjustment circuit means comprises:

first circuit means for generating first reference clock pulses to determine a timing of said drive pulses to be provided to said image sensing means from said driver circuit means, said first circuit means being coupled to said driver circuit means;

second circuit means for generating second reference clock pulses to determine a timing for said start pulses to be provided to said image sensing means from said driver circuit means, said second circuit means being coupled to said driver circuit means;

third circuit means for detecting a peak level of the electrical analog signal produced from said image sensing means; and

fourth circuit means for adjusting a timing of said second reference clock pulses to be generated from said second circuit means in response to the output from said third circuit means,

the time interval of said start pulses to be provided to said image sensing means from said driver circuit means being adjusted by adjusting the timing of said second reference clock pulses to be generated from said second circuit means.

32. An apparatus according to claim 31, wherein said second circuit means is so arranged that the same is coupled to said first circuit means, and generates said second reference clock pulse at every predetermined number of said first reference clock pulses to be generated from the first circuit means;

and said fourth circuit means is so arranged that the same is coupled to said first circuit means, and adjusts said timing of said second reference clock pulses to be generated from said second circuit means by adjusting the timing of said first reference clock pulses to be generated from said circuit means.