| 摘要 |
519,496. Gramophone pick-up arm control mechanism. GARRARD ENGINEERING & MANUFACTURING CO., Ltd., and OFFEN, F. J. Nov. 4, 1938, No. 32040. [Class 40 (ii)] Relates to pick-up control mechanism for use in automatic gramophones having a feeler arm which is moved into and out of contact with the edge of a positioned record to detect its diameter. According to the invention, the return movement of the feeler arm is utilized to cause a pressure yieldably to be, applied to the pick-up arm to push the pick-up needle into the starting groove of the record after it has been deposited on the edge of the record. As shown in Fig. 1, the pick-up arm 1 is pivoted on an horizontal pivot 3 on an arm 4 on a vertical rotatable spindle 5 through which a rod 6 passes for lifting and lowering the pick-up. The diameter of the record is detected by a " feeler" arm 21 having a roller 22 at its free end which is brought against the edge of the record under the influence of a spring 28, Fig. 2, when a drum cam 26 co-operating with a lever 23 on the spindle 24 of the feeler arm 21 allows the inward movement of this lever. After this, a cam 19a allows a bell-crank 14 to be moved by a spring 20 to cause a lug 13 thereon to bear on a pin 16 on a lever 17 fast with the sleeve 5 and thereby swing the pick-up arm inward. This inward movement is limited by the abutment of a stop 36 on the lever 17 against a pin 30 or 31 on a lever 29 fast on the spindle of the feeler arm 21 according to the diameter of the record. The needle 2 is now just over the edge of the record and is lowered thereon by the co-operation of cam 12a with lever 7 pivoted at 8 and having a forked end 9 bearing on a collar 10 on the rod 6. During this lowering operation, horizontal displacement of the pick-up arm is prevented by a frictional grip due to the wedging of the pin 30 or 31 between the stop 36 and a rectangular stud 37 on the lever 17. After the needle has been lowered, drum cam 26 operates to withdraw the feeler arm 21 from the edge of the record, whereupon the pin 30 or 31 acts on lug 35 on a small lever 33 pivoted at 32 on the lever 17 and influenced by a spring 34 anchored to the lever 17. This spring thus transmits movement to the lever 17 causing the needle to be moved inward to engage the starting groove of the record. When the record is played, the needle follows the grooves and the lever 17 moves freely away from the reach of levers 14 and 29. This pick-up control mechanism may be used with the record-changing mechanism described in Specification 486,999 and with the record-delivery mechanism described in Specification 511,840. |
