| 摘要 |
PURPOSE:To correct a shift in access position and distortion of a pickup tube, by providing a character line detection pattern and 1st and 2nd character position detection patterns in a beam scanning system which reads character patterns by a pattern generator. CONSTITUTION:Together with a character pattern, 2nd character position detection pattern 6 at the upper part of the character pattern region indicated by dotted lines, 1st character position detection pattern 5 at the left upper part extending to both adjacent character pattern regions, and character line detection pattern 7 at the left side part at the circumference are printed by holography. An electron beam is moved in the Y-axial direction to detect character line detection pattern 7 and then moved in the X-axial direction to detect 1st character position detection pattern 5. Next, it is moved in the X-axial direction by a fixed distance to fix an initial point and the read signal of the character pattern is controlled by detecting 2nd character position detection pattern 6. |
