Patent GB-483377-A (GB)
Title: Improvements in gramophone and the like apparatus
IPC: G11B17/02
Filed: 1936-10-23
Abstract: 483,377. Gramophones. WILKINSON, R. Oct. 23, 1936, No. 25893. [Class 40 (ii)] A gramophone is provided with means for allowing the tone-arm to be automatically lifted from the disc record at any point determined at will in its travel radially of the record, and to be then operated by mechanism automatically clutched to a rotating part of the machine to return it towards the start, together with means for independently adjusting the amount of its angular displacement from any point on the record at which it is raised to the point at which it will be automatically redeposited on the record. In the construction shown, the tone-arm J, Fig. 1, is carried by an horizontal pivot 5 on a plate 96 mounted on a vertical pivot 3. A pin 72 on a bracket 49 on the plate 96 is gripped lightly by scissor arms 69, 70 by spring 71. The extension 68 of arm 69 is pivoted at 195 to a lever 66 pivoted at 67 to another lever 65 pivoted at 193 on a fixed plate 98. The lever 65 carries an insulating plate 99 provided with a stop pin 83 and an electric contact pin 84 limiting the swing of the lever 66. During play, an arcuate face 64 on the lever 65 is gripped with slight friction by the end 59 of a lever 60 pivoted at 62 and influenced by a spring 94. Soon after play starts, lever 66 is swung by its connection with the tone-arm from stop 83 to contact 84, thereby establishing connection from a mains terminal 107 through frame of machine and lever 66 to one terminal of an electromagnet 30, the other terminal of which is connected to an insulated contact 29. Another electromagnet 17 has one terminal connected to an insulated contact 93, and its second terminal connected to terminal 14 of switch 16, the other terminal 15 of which is connected to a lever 79 pivoted at 78 and in contact with a pin 76 establishing connection through the frame of the machine to mains terminal 107. The other mains terminal is constituted by an insulated lever 27 pivoted at 28 and connected by a link 26 to a lever 21 pivoted at 22 and normally locked by armature 18 of electromagnet 17. The lever 21 and another lever 23 pivoted at 25 are urged towards each other by a spring 24, and the lever 23 is held away by the pin 76. Whenever it is desired to stop the play to repeat a portion of the record, the switch 16 is closed to complete circuit of electromagnet 17. The armature 18 of this electromagnet is attracted and releases lever 21, which is moved by spring 24 to rock lever 27 from contact 93 to contact 29, thereby cutting off electromagnet 17 and completing circuit of electromagnet 30. The armature 31 of this electromagnet is attracted and releases a lever 33 pivoted at 35. This is swung counterclockwise by a spring urged pawl 38 pivoted at 92 on the underside of a cam 50, Fig. 3, rigid with another cam 13. The pawl then engages a ratchet wheel 12, which is driven through gearing 10, 8, 6 by the spindle 7 of the turntable, and the cams make one revolution. The cam 13 first rocks a lever 41 pivoted at 42, causing the end 44 of this lever to ride over inclined end 45 of lever 46, and the other end 85 of lever 46 to be lifted into frictional engagement with a depending finger on the plate 96, whereby the tone-arm is lifted off the record. Next the cam 50 rocks lever 51 pivoted at 52 to bring end 54 of said lever to bear against slanting edge 55 of lever 46, whereby lever 46 is swung horizontally about its pivot 47 to move the tone-arm back. The lever 46 has a loose fit on its pivot 47 to allow for both its vertical and horizontal movements. The rest position of the lever 46 is determined by an adjustable stop 57, and this determines the angle by which the tone-arm is swung back. When the back swing is completed, cam 13 allows lever 41 to be returned by its spring 43 to permit the tone-arm to drop down into engagement with the record and cam 50 similarly allows return of lever 51 by its spring 53 to allow the lever 46 to be returned by its spring 100 against the adjustable stop 57. During the rotation of the cams the pin 76, which is carried by cam 13, moves away from levers 32, 79. The terminal 15 of switch 16 is thus disconnected from the mains terminal 107. Meanwhile, levers 21, 23 under influence of their spring 24 exert a strong gripping pressure through lever 60 on arcuate face 64 of lever 65 to maintain the position of this despite the backward swing of the tone-arm, which draws lever 66 away from contact 84. The pin 76 on its way round first encounters lever 21 and restores this into engagement with armature 18 of electromagnet 17, then makes contact with arm 77 rigid with lever 79 thereby again connecting switch terminal 15 to mains terminal 107, and finally bears on lever 23 and restores it to normal position. Near the end of the rotation of the cams, cam 13 bears on tail 104 of lever 33 and restores this into engagement with armature 31 of electromagnet 30, and pawl 38 is then rocked by stop 36 on lever 33 and disengages ratchet wheel 12. The tone-arm after it has been moved back and re-engaged with the record repeats the part of the record over which it has been swung back : and when this is completed, lever 66 touches contact 84 and, if switch 16 is again pressed or has been kept pressed, this part of the record is again repeated. A press button switch 80 is provided by means of which, when the switch 16 is in the closed position, the circuit of electromagnet 30 can be kept closed ; so that when both switches 16 and 80 are closed, the lever 33 is not re-engaged by the armature 31 of electromagnet 30 when the cams 13, 50 have completed one revolution. and these cams proceed on a second revolution. During this second revolution, the tone-arm is again lifted and moved back. In this way, the tone-arm can be moved back in steps through an angle which is any desired multiple of the angle set for an individual step by the stop 57.