Apparatus for detecting edge position of elongated article

• US 4,974,077 A
• Filed: 07/31/1989
• Issued: 11/27/1990
• Est. Priority Date: 08/05/1988
• Status: Expired due to Fees

• Current Assignee: Bridgestone Corporation
• Original Assignee: Bridgestone Corporation
• Inventors: Kusaba, Takeshi
• Primary Examiner(s): Britton, Howard W.
• Assistant Examiner(s): Lee, Michael
• Application Number:
  US07/387,041
• Time in Patent Office: 484 Days
• Field of Search: 358/101, 358/107, 358/98, 382/18, 382/8, 382/22
• US Class Current: 382/141
• CPC Class Codes: G01B 11/028 by measuring lateral position of a boundary of the object G01B11/022, G01B11/024, G01B11/04 take precedence

Abstract

An apparatus for detecting an edge position of an elongated article in which an image of the edge portion of the object is picked up by a two-dimensional television camera arranged above the article such that the scanning line of the television camera is made substantially parallel with the edge portion of the article, an image signal of the image of the edge portion is converted into a bivalent signal representing black and white pixels, the number of the black pixels in every scanning line is counted to obtain an histogram, a scanning line number at which the number of the black pixels is abruptly increased in the histogram is detected as the edge position of the article.

Claims

1. An apparatus for detecting an edge position of an elongated tire construction member having front and rear edge portions comprising:

a light source means for projecting an illumination light at least to an edge portion of the member to be detected;

a two-dimensional television camera means for picking up an image of the edge portion of the member to produce an image signal, said television camera means being arranged such that scanning lines of the television camera means are substantially parallel with a width direction of the edge of the member;

means for converting said image signal into a bivalent signal representing white and black pixels;

means for counting the number of the white or black pixels of the bivalent signal in every scanning line to make a histogram of the white or black pixels;

edge detecting means for receiving the histogram and detecting the rear edge position of the member in accordance with a change in the number of the white or black pixels in the histogram said edge detecting means comprising photoelectric timing detecting means for detecting the front edge portion of the member comes within a field of view of the television camera and producing a detection freeze signal; and

means responsive to said detection freeze signal of the first edge portion of the member to freeze said image from the television camera means so that an image signal of rear edge of the elongated member is extracted to derive said histogram.

2. An apparatus according to claim 1, wherein said television camera means comprises a two-dimensional television camera.

3. An apparatus for detecting an edge position of an elongated member having a front and rear edge portions according to claim 1 further comprising:

means for conveying the elongated member in a longitudinal direction of the member.

4. An apparatus according to claim 1, wherein:

said photoelectric timing detecting means is arranged to be separated from the television camera means by a standard length of the member and comprises a light source and photoelectric switch arranged on respective sides of the member, said detection signal being generated when the second edge portion of the member is detected by said photoelectric switch.

5. An apparatus according to claim 4, wherein:

said image signal freezing means comprises a memory for storing the image signal of the first edge portion of the article supplied from the television camera in response to the detection signal.

6. An apparatus according to claim 1, wherein:

said counting means comprises a circuit for counting the number of black level pixels in every scanning line and a circuit for making a histogram in accordance with the number of the black pixels.

7. An apparatus according to claim 6, wherein;

said edge position detecting means detects as the edge position a scanning line at which the number of the black level pixels firstly exceeds a predetermined threshold number.

8. An apparatus according to claim 7, wherein:

said television camera has two hundreds and fifty six (256) scanning lines each having two hundreds and fifty six (256) pixels and said predetermined threshold number is set to about one hundred (100).

9. An apparatus according to claim 5, further comprising:

means for calculating a length (l) of the member from a distance (L) between a center of the field of view of the television camera and the timing detecting means, and a distance (l_x) between the center of the field of view of the television camera and the scanning line at the rear edge position.

10. An apparatus according to claim 9, wherein:

said elongated member is a tread rubber for use in manufacturing tires, and a length of the tread rubber is measured by detecting an edge position having an acute angle viewed from a side by means of the photoelectric switch of the timing detecting means and an edge position having an obtuse angle viewed from a side by means of the television camera.