| 摘要 |
PURPOSE:To accurately determine the front and rear of a flat mask in a non- contact method by spacing an eddy current type non-contact displacement gauge at specified intervals from the surface of the flat mask and determining the front and rear depending upon the magnitude of the output voltage. CONSTITUTION:Since the hole area ratio (%) in a fixed area when the surface (front) with the small hole 7 of a flat mask 6 is opposedly spaced at specified intervals (d) to an eddy current type non-contact displacement gauge 3 is smaller than that (%) when the surface (rear) with the large hole 8 of the flat mask 6 is opposedly spaced at specified intervals (d) to the eddy current type non-contact displacement gauge 3, the output from the displacement gauge is set to 5.40V, for example, on a straight line 15 when the rear is measured provided that the output from the displacement gauge is set to 4.22V, for example, when the front is measured. As a result, the front and rear of the flat mask can simply be determined depending upon the magnitude of the output voltage of the eddy current type non-contact displacement gauge. |
