| 摘要 |
PURPOSE:To eliminate the unstability of an imposing state according to thickness of printing and to greatly improve the accuracy of writing and reading by attaching discrimination codes to the non-recording layer forming parts of the inside surface of disk-shaped substrates. CONSTITUTION:Two sheets of the disk-shaped substrates 11, 12formed with the recording layers 11a, 12a on the inside surface side are joined via toric spacers 13, 14 near the inner peripheral and outer periphery thereof and spindle insertion holes 15 are provided to the central part thereof. The discrimination codes such as lot control No. are printed to the non-recording layer forming part 11b and/or 12b on the inner surface side of the disk-shaped substrate 11 and/or 12. The printing range is preferably between the outer periphery 16 of the contact surface of the spacer 13 on the inner peripheral side and the inner edge 17 of the recording layers 11a, 12a. The discrimination codes can be sufficiently put on if the printing is set to the size within the range of 3mm height and 13mm length. The inverted characters the outer side faces of which are positive are adequate for printing to facilitate reading from the outside of the substrates. |
