| 摘要 |
The feed mechanism has a lead screw 11, a pickup assembly 12, an engagement piece 13, and a restrictor piece 14, a compressed coil spring 15, and a bearing portion 16. The engagement piece 13 has a thread portion 41 engaged with a screw groove 23 of the lead screw 11. The engagement piece 13 moves along the lead screw 11 and can come close to and off from the lead screw 11. The pickup assembly 12 moves together with the engagement piece 13. The restrictor piece 14 prevents the engagement piece 13 from disengaging from the lead screw 11, except when the screw groove 23 moves apart from the thread portion 41. The compressed coil spring 15 urges the engagement piece 13 toward the lead screw 11. The bearing portion 16 rotatively supports the lead screw 11 and allows the lead screw 11 to move apart from the engagement piece 13 when the engagement piece 13 has reached an end thereof.
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