Method of inspecting solid body for foreign matter

• US 5,444,480 A
• Filed: 10/22/1993
• Issued: 08/22/1995
• Est. Priority Date: 10/26/1992
• Status: Expired due to Fees

• Current Assignee: Kirin Techno-System Company, Limited (Kirin Holdings Company Limited)
• Original Assignee: Kirin Techno-System Company, Limited (Kirin Holdings Company Limited)
• Inventors: Sumita, Masahiko
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US08/139,801
• Time in Patent Office: 669 Days
• Field of Search: 348/127, 348/128, 348/131, 382/8, 250/223 B, 356/240
• US Class Current: 348/127
• CPC Class Codes: G01N 2021/8893 providing a video image and a processed signal for helping visual decision
• CPC Class Codes: G01N 21/9027 in containers after filling
• CPC Class Codes: G01N 21/94 Investigating contamination, e.g. dust G01N21/85 takes precedence
• CPC Class Codes: G01N 33/0081 Containers; Packages; Bottles

Abstract

Small pieces of foreign matter on the surface of a cake such as freeze-dried preparations in a vial are detected as distinguished from cake surface irregularities including cake collapses and cracks that should be passed as being acceptable. The cake is imaged by a CCD camera or the like to produce an image signal representing an image of the cake. The level of an image signal which is higher than a predetermined upper limit is set to the upper limit and the level of an image signal which is lower than a predetermined lower limit is set to the lower limit. At least three pixel points, which include a point of interest and surrounding points one on each side of the point of interest, in an inspected region of the image are compared, and the point of interest is judged as being an abnormal point if the point of interest is brighter or darker than the surrounding points. An area in the inspected region is determined as containing foreign matter if the count of abnormal points in the area is larger than a predetermined lower limit and smaller than a predetermined upper limit.

Claims

1. A method of inspecting a solid body for foreign matter thereon, comprising the steps of:

(a) producing an image signal representing an image of a solid body;

(b) setting a level of an image signal which is higher than a predetermined upper limit to an upper limit and another level of an image signal which is lower than a predetermined lower limit to a lower limit; and

(c) comparing at least three pixel points, which include a point of interest and surrounding points one on each side of the point of interest, in an inspected region of the image, and judging said point of interest as being an abnormal point if the point of interest is brighter or darker than said surrounding points.

2. A method as claimed in claim 1, and further comprising:

(d) determining an area in said inspected region as containing foreign matter if a count of abnormal points in said area is larger than a predetermined lower limit and smaller than a predetermined upper limit.

3. A method according to claim 1, wherein said step (c) comprises the steps of:

converting each of said pixel points to a binary signal each representing a bright or dark level with a constant threshold; and

logically processing the binary signals of the pixel points to judge said abnormal point existing on said solid body.

4. A method according to claim 1, wherein said image signal is a digital image signal converted from an analog signal of an imaging unit.

5. A method according to claim 1, wherein said solid body is a cake of a freeze-dried preparation filled in a vial.

6. A method according to claim 1, wherein a distance between said surrounding points is larger than a size of a small piece of foreign matter.

7. A method according to claim 1, wherein said level of predetermined upper limit is lower than the level of an bright area produced from a collapse on a surface of said solid body.

8. A method according to claim 1, wherein said level of predetermined lower limit is higher than the level of a dark area produced from a crack on a surface of said solid body.