GB743522A - Improvements in or relating to gramophone record playing mechanisms - Google Patents

Abstract

743,522. Gramophone record players. TELEFUNKEN GES., [formerly TELEFUNKEN GES. FUR DRAHTLOSE TELEGRAPHIE]. April 28, 1952 [April 28, 1951], No. 10636/52. Class 40(2) The two styli in a machine playing standard or microgroove records are so coupled to the speed changing mechanism that on changing the speed, the appropriate stylus is brought into position. The pressure of the pick-up and the response of the associated amplifier may also be varied. The tone arm 3, Fig. 1, mounted on the spindle 2 has a pick-up head 4 which can be rotated round spindle 5 so that either stylus 16 'for microgroove records, or stylus 17 for standard records, is in the playing position. The change over of speeds is effected by a knob 14 fitted to a spindle 12 of the gear changing device 13. The turning of knob 14 causes cable 8 to be wound on to, or unwound from, spindle 12, and causes the pick-up head 4 to swivel clockwise about the spindle 5 or allows spring 7 to swivel the head 4 anti-clockwise. A spring 15 is fixed to the spindle 2 and reduces the pick-up pressure by bearing on the wedge 9 when cable 8 is shortened on changing the speed to 45 or 33<SP>1</SP>/ 3 r.p.m. Cable 8 may also operate a switch (not shown) which adjusts the means for varying amplifier response. In a modification Fig. 3 (not shown) the tone arm support, which supports the tone arm in the inoperative position, co-operates with a lever system for changing over the pick-up head and altering the pressure of the pick-up when the change-speed knob is tuned. To prevent the changing over of the speed control during the playing of the record, a disc 32 (Fig. 5) is fitted to spindle 12, and is provided with recesses 33, corresponding to 33<SP>1</SP>/ 3 , 45 and 78 r.p.m. When the tone arm is off the rest 40, the extension 38 of lever 36 engages in these recesses under the influence of compression spring 46, thus preventing the rotation of knob 14. When the tone arm is on the rest 40, the end 39 of lever 36 is pressed down against spring 46 by the tone arm, so disengaging extension 38 from disc 32, to allow the knob 14 to be turned, if desired. The rods 41, 42 coupled to disc 32, rotate the pick-up head 4 when knob 14 is turned. Specification 678,705 is referred to. Reference has been directed by the Comptroller to Specification 698,865.