| 摘要 |
PURPOSE:To check automatically the focus without intervention of manual operation by observing a test pattern for test displayed on a CRT with a picture input device such as a TV camera and allowing a computer to analyze the degree of out of focus. CONSTITUTION:After a luminance value of a cathode ray tube screen is stored to a luminance observing value storage buffer 12, a luminance difference A between a tube screen luminance measuring section 13 and a maximum luminance measuring section 14 and a luminance difference B between a grating pattern maximum luminance measuring section 15 and a minimum luminance measuring section 16 are obtained. A division circuit 17 obtains a value of luminance difference B/luminance difference A, the value is stored in a focus measuring value storage section 18, and a focus measuring value is obtained. The operation is repeated by MXN times, the focus measuring values of MXN sets are obtained, the average value is obtained at a mean value processing section 22 and stored in a focus storage section 23. Then a inspection decision section 20 inspects whether all focal ratio are >=0.6 and whether or not the difference between the maximum value and the minimum value is within 0.1.
|
