Plug gap measuring device, plug gap measuring method, and spark plug manufacturing method

摘要

PROBLEM TO BE SOLVED: To provide a plug gap measurement device capable of measuring a plug gap of an ignition plug with accuracy.SOLUTION: A plug gap measurement device 10 measures a plug gap g between a ground electrode 11 and a center electrode 12 included in an ignition plug 1. The measurement device 10 comprises: first illumination parts 41 and 61 irradiating the ground electrode 11 and the center electrode 12 so as to form a silhouette image; second illumination parts 42 and 62 irradiating an electrode surface of the ground electrode 11; and third illumination parts 43 and 63 irradiating an electrode surface of the center electrode 12. In addition, the plug gap measurement device 10 comprises: a first camera 3 and a second camera 5 having telecentric optical systems 31 and 51, respectively; and an image processing part 7 measuring the plug gap g on the basis of images captured from both sides of the ignition plug 1 by the first camera 3 and the second camera 5.