Method for examining foreign matters in through holes

• US 7,043,072 B2
• Filed: 03/29/2001
• Issued: 05/09/2006
• Est. Priority Date: 04/27/2000
• Status: Expired due to Fees

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Goto, Noboru, Saito, Mikio
• Primary Examiner(s): Bali, Vikkram
• Application Number:
  US09/821,816
• Publication Number:
  US 20030206651A1
• Time in Patent Office: 1,867 Days
• Field of Search: 382/152, 382/141, 382/145, 382/147, 382/149, 348/87, 348/125, 348/126, 356/237.1, 356/237.6, 702/35, 702/36
• US Class Current: 382/152
• CPC Class Codes: G01N 2021/95653 Through-holes
• CPC Class Codes: G01N 21/94 Investigating contamination, e.g. dust G01N21/85 takes precedence
• CPC Class Codes: G01N 21/95692 Patterns showing hole parts, e.g. honeycomb filtering structures

Abstract

Provided herein are a method and an apparatus for examining foreign matters in through holes, which can quickly conduct an examination of foreign matter in through holes with low costs and high accuracy. Light passing through a plurality of through holes having a uniform size is simultaneously taken as image data, the number of areas of the imaged masses corresponding to the plurality of the respective through holes is initially counted, and a process to determine presence or absence of foreign matters is conducted by mutually comparing areas of adjacent masses for only a work piece with a counted value of the masses being concurred with a specified value.

Claims

1. A method for examining foreign matters in through holes in a work piece, comprising:

passing light through a plurality of through holes having a uniform size to take image data;

initially counting a number of light receiving regions that correspond to the imaged respective through holes to determine a number of regions;

determining whether the number of regions for the work piece concurs with a specified value;

comparing, if the number of regions for the work piece concurs with the specified value, a difference in area between adjacent light receiving regions; and

determining a presence or absence of foreign matters in the through holes depending on whether the difference in area is greater than a specified difference in area.

2. A method for examining foreign matters in through holes according to claim 1, wherein the counting of light receiving regions is conducted only for those of the extracted light receiving regions whose area values are within a specified range.

3. A method for examining foreign matters in through holes according to claim 1, wherein, when the number of light receiving regions counted in the step of counting the number of light receiving regions does not concur with a specified value, the examination is ended.

4. A method for examining foreign matters in through holes according to claim 1, wherein an image is taken with an imaging focal point of a sensor camera being shifted from a surface of the work piece, such that the image is taken with an image area of light passing through the through hole being expanded.

5. A method for examining foreign matters in through holes in a work piece, comprising:

passing light through a plurality of through holes having a uniform size to take image data;

counting a number of light receiving regions that correspond to the imaged respective through holes to determine a number of regions subject to the extracted light receiving regions having area values being within a specified range;

determining whether the number of regions for the work piece concurs with a specified value;

comparing, if the number of regions for the work piece concurs with the specified value, a difference in area between adjacent light receiving regions;

determining a presence or absence of foreign matters depending on whether the difference in area is greater than a specified difference in area; and

ending the examination when the number of the light receiving regions counted in the step of counting the number of light receiving region does not concur with the specified value.

6. A method for examining foreign matters in through holes according to claim 5, wherein an image is taken with an imaging focal point of a sensor camera being shifted from a surface of the work piece, such that the image is taken with an image area of light passing through the through hole being expanded.

7. A method for examining foreign matters in through holes in a work piece, comprising:

passing light through a plurality of through holes having a uniform size to take image data;

dividing the image data into groups and reading the image data for each examination region;

initially counting the number of imaged light receiving regions that correspond to the respective through holes to determine a number of regions in the examination region; and

determining whether the number of regions for the work piece concurs with a specified value;

comparing, if the number of regions for the work piece concurs with the specified value, a difference in area between adjacent light receiving regions; and

determining a presence or absence of foreign matters depending on whether the difference in area is greater than a specified difference in area.

8. A method for examining foreign matters in through holes according to claim 7, wherein an image is taken with an imaging focal point of a sensor camera being shifted from a surface of the work piece, such that the image is taken with an image area of light passing through the through hole being expanded.