Patent ID: 9270088
Filing Date: 2016-02-23
CPC Classification: H01T,H04N

Claim Text:
1. A method for inspecting a spark plug comprising the steps of: providing a tubular insulator having an axial hole extending in a direction of an axis, a center electrode inserted into the axial hole at a front end side thereof, a tubular metallic shell disposed around the insulator, an annular space defined by an outer circumferential surface of the insulator and an inner circumferential surface of the metallic shell and opened frontward; applying a voltage to the center electrode; photographing an area including at least the center electrode, the insulator, and the annular space from a front end side in the direction of the axis to obtain an image when the voltage is applied to the center electrode; detecting a discharge in the photographed area; determining whether a dielectric breakdown has occurred based on the photographed image including the insulator and the annular space; and inspecting an insulation performance of the insulator based on a result of the determining step.