| 摘要 |
PURPOSE:To evaluate easily the scanning capacity of a scanning system by using the moire generated by relations between intervals of arrangement of photodetector groups and the width and intervals of lines of concentric circle patterns which are written on an original and constitute a test chart. CONSTITUTION:The width of lines of circles 1 is approximately equal to the interval between lines and is set to a value which is about 1.6 times as long as the interval between picture elements of main scanning. Reference lines 2 and 3 are so described that they coincide with the main scanning direction X and the subscanning direction Y in an ideal picture scanning system. When this test chart is read by a device, moires shown in the figure by (a), a', (b), and b' are generated in the main scanning direction and the subscanning direction. Symmetrical axes of moires (a) and a' and moires (b) and b' are denoted as l1 and l2 respectively, and an angle theta1 between the axis l1 and the reference line 1 and an angle theta2 between the axis l2 and the reference line 2 are obtained with angle indicating lines 4 and 5, thereby detecting the inclination of the read original, the inclination of an image sensor, etc.
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