Method for finding disconnection of conductive wires formed on plate glass and apparatus therefor

• US 7,332,718 B2
• Filed: 07/22/2003
• Issued: 02/19/2008
• Est. Priority Date: 01/24/2002
• Status: Expired due to Fees

• Current Assignee: Central Glass Company Limited
• Original Assignee: Central Glass Company Limited
• Inventors: Okamura, Shinichi, Ookita, Masahiko
• Primary Examiner(s): Porta; David
• Assistant Examiner(s): Taningco; Marcus H
• Application Number:
  US10/623,604
• Publication Number:
  US 20040124358A1
• Time in Patent Office: 1,673 Days
• Field of Search: 250/341.1, 250/330, 250/332, 702/84, 374/5, 374/124, 374/121, 324/501, 438/17
• US Class Current: 250/341.1
• CPC Class Codes: G01J 5/0096 for measuring wires, electrical contacts or electronic systems
• CPC Class Codes: G01N 25/72 Investigating presence of flaws
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: G01R 31/54 Testing for continuity
• CPC Class Codes: G01R 31/58 Testing of lines, cables or conductors testing of electric windings G01R31/72
• CPC Class Codes: H05B 1/0236 for vehicles
• CPC Class Codes: H05B 2203/035 Electrical circuits used in resistive heating apparatus
• CPC Class Codes: H05B 3/84 Heating arrangements specially adapted for transparent or reflecting areas, e.g. for demisting or de-icing windows, mirrors or vehicle windshields

Abstract

The invention relates to a method for finding disconnection of a conductive wire formed on a plate glass. This method includes the steps of (a) applying a voltage to the conductive wire; and (b) imaging thermal radiation from a surface of the conductive wire by an infrared image sensor, while the step (a) is conducted, thereby producing a temperature distribution image. An apparatus for conducting the method includes (a) a power source for applying a voltage to the conductive wire; and (b) an infrared image sensor for imaging thermal radiation from a surface of the conductive wire, thereby producing a temperature distribution image.

Claims

1. A method for finding disconnection of a plurality of conductive wires that are formed on a vehicular plate glass and are parallel with each other, the method comprising the steps of:

(a) applying a voltage to the conductive wires;

(b) imaging thermal radiation from a surface of the conductive wires by an infrared image sensor, while the step (a) is conducted, thereby producing a temperature distribution image;

(c) selecting an inspection portion from the temperature distribution image, the inspection portion having a size to cover only a portion of each conductive wire;

(d) subjecting only the inspection portion of the temperature distribution image having a size less than the entirety of each conductive wire to a binarization by an image processor, thereby producing a binarized temperature distribution image of only the inspection portion; and

(e) comparing the binarized temperature distribution image with a data representing a pattern of the conductive wires to determine whether a disconnection exists anywhere in the entirety of the conductive wires, based on the binarized temperature distribution image of only the inspection portion.

2. A method according to claim 1, wherein the data of the step (e) is a first image data obtained by drafting the pattern of the conductive wire.

3. A method according to claim 1, wherein the data of the step (e) is a second image data obtained, prior to the step (a), by imaging thermal radiation from the surface of the conductive wires by the infrared image sensor.

4. A method according to claim 1, wherein the comparison of the step (e) is conducted by superimposing the binarized temperature distribution image on the data.

5. A method according to claim 1, wherein the comparison of the step (e) is conducted by an image data subtraction between the binarized temperature distribution image and the data.

6. A method according to claim 1, wherein the conductive wires serve as heating wires for providing an antifogging property or as antenna wires.