Patent GB-496127-A (GB)
Title: Apparatus for reproducing sound
IPC: G11B7/28
Filed: 1937-05-21
Abstract: 496,127. Sound-reproducing apparatus. PARFITT, A. W. (Translaphon Corporation) May 21, 1937, No. 14156. [Class 40 (ii)] [Also in Groups XX and XXXIX] The matter on a disc record 17, Fig. 1, is represented on a graduated chart 168, and the apparatus is adapted to reproduce and repeat any section of the record corresponding to any indicated part of the chart. The main feature of the invention resides in a slide, hereinafter called a traveller, reciprocating between adjustable stops to determine by its double stroke how many convolutions of the record shall be played and repeated. An optical projecting apparatus may be associated with the chart, a lantern slide replica of the chart being automatically adjusted by the indicator of the chart, so that a view corresponding to the indicated part of the chart may be made visible to a number of persons listening to the reproduction of the corresponding section of the record. The record may be of language, music, telegraphic code, or other sounds ; and the chart may give translations or corresponding visual indications. The chart 168, which is detachably fitted in a U-shaped grooved holder 167, comprises four columns, each with a scale 171 of 100 divisions giving a total of 400 graduations corresponding to the convolutions of a twelveinch record. A charting arm 175 can slide laterally over the chart to bring its graduated edge 177 against any one of the four correspondingly graduated scales 171, and a pointer 176 can slide along the charting arm to any desired graduation of the scales. The charting arm is attached to a carriage 182, Fig. 2, slidable on a transverse rod 184, a yielding spring catch 188 on the carriage co-operating with notches 185 on the rod at positions corresponding to the four columns of the chart. The pointer 176 is attached to an endless band 206 stretched between a pulley 207 and a sprocket wheel 205, and is adjusted by a knob 212. A pinion on the spindle of the sprocket wheel 205 meshes with a rack 199 slidably mounted in the carriage 182 and attached to an endless band 194 stretched between a large sprocket wheel 195 and a pulley 196. Another endless band 219 is stretched between a pulley 220 and a small sprocket 218 on the spindle 216 of the large sprocket wheel 195. The band 219 is attached to a tone-arm carriage 117 slidable on a transverse shaft 118. By this mechanism, the adjustments of the charting arm and of the pointer thereof are transmitted to the tone-arm carriage, which thus takes a position determining the beginning of a desired section of the record in accordance with the position of the pointer on the chart. The tone arm 8, Fig. 8, is mounted on an horizontal pivot 141 on a bracket 139 extending from a sleeve 135 on a vertical pivot 116 on the tone-arm carriage 117, which can slide on the shaft 118 but is splined to rock therewith to lift the needle off the record when the tone arm is to be moved back. A set screw 143 at the end of the arm 139 bears under the tone arm to lift it when the shaft 118 is rocked. The carriage 117 has a depending arm 125, Fig. 3, on which a spring 126 acts to tend to lift the needle off the record ; but during play this is prevented by an arm 133 of the carriage, provided with rollers 127, 128 bearing on a flange of a cam-bar 123, supported by a roller 124. The roller 124 is carried by the traveller 40a, which slides on transverse rod 42. When the reproduction of the selected section of the record is completed, the roller 124 comes under a recess 129, Fig. 13, in the cam-bar 123, whereupon the cam-bar falls and the tone-arm carriage 117 rocks and lifts the needle off the record. After the needle has left the record, a roller 153, adjustably set on a resetting lever 144 pivoted on the carrier 117 bears against a stop bar 145, and the lever 144, is rocked to restore the tone arm to the beginning of the selected section. For this purpose, a sector 136 adjustably attached to the sleeve 135 is formed with a pair of shoulders 149, Fig. 2, and the upper end of the lever 144, which is forked, is provided with a pair of rollers 148, which come to bear on the shoulders 149 to swing the tone arm back to starting position. The needle is again brought down into engagement with the record groove and the reproduction is repeated when the traveller carries the roller 124 away from the recess 129 ; and reproduction is again stopped when the traveller returns the roller to the recess. The length of the double stroke of the traveller determines the number of record grooves which are reproduced. The traveller 40a, which is slidably mounted on the rod 42 by means of a sleeve 41, has a depending arm 43 fitted with a pair of rollers 44 embracing a guide flange 45, which maintains the traveller upright. The upper part of the traveller has a hollow chamber 46, Fig. 15, in the walls of which are slidably mounted two half nuts 39, 40 at the ends of a stem 51 fitted with a double conical collar 59. The half nuts co-operate alternately with screw shafts 28, 29. These shafts are interconnected by spur pinions 37, 38, Fig. 2, rotated in opposite directions, and the screw shaft 28 is fitted with a sprocket wheel 31 driven by a chain 32 from a sprocket wheel on a side shaft of the motor, which drives the record turntable. On top of the chamber 46 in the traveller, a slide 54 is mounted with a depending cage 55 containing an annular coiled spring 60 around the stem 51. Movement of the slide from one side to the other causes the spring 60 to ride and snap over the collar 59 and move the stem 51 in the opposite direction, thereby withdrawing one of the half nuts 39, 40, from one of screw shafts 28, 29 and moving the other half nut into engagement with its screw shaft. A reverse movement of the slide reverses the engagement of the half nuts. The slide is reciprocated by means of a pin 74, Fig. 14, thereon in engagement with a slot 73 in a bell crank lever 69 pivoted at 72 on the traveller 40a. When the traveller driven by one of the screw shafts 28 or 29 reaches one end of its stroke, an arm 75 of the bell-crank lever 69 is deflected by an adjustable block 70, Fig. 13, and the slide 54 thereby shifted from one side to the other, reversing the engagement of the half nuts and causing the traveller to move in the reverse direction. At the end of this return stroke the arm 75 is deflected by another adjustable stop 71, the slide 54 is thereby shifted back and the traveller again driven in the first direction. This operation may be stopped by the manual depression of a stem 61, the conical point 65 of which cooperates with a correspondingly shaped recess on the stem 51 to put this stem in central position with both half-nuts out of action. The recess 129 of the previously mentioned cam-bar 123 is situated on the same side as the block 71. The block 71 when in its innermost position causes the repetition of the reproduction immediately after the tone arm has been lifted and returned by the co-operation of the recess 129 with the roller 124 on the traveller. The adjustment of the block 71 outwards determines a period of silence between two successive sound reproductions. The block 71 is provided with a rack 86 in mesh with a pinion 87 on a shaft 88 provided with an operating knob 90 having an indicating pointer 92, Fig. 1, over a scale 93. The other block 70 is provided with a projection 105, Fig. 14, extending in a worm groove 106 in a worm shaft 99 geared to a graduated drum 110, Figs. 1 and 2, co-operating with a fixed indicating pointer 173. The drum has 400 graduations corresponding to the number of grooves on a 12 inch record. When the roller 124 is under the cut-out portion 129, of the cam-bar 123, the shaft 118 may be rocked by the manual operation of a lever 154 pivoted at 155, Fig. 21, and provided with an eccentric part 156 engaging a slot 157 in a rocker arm 120 on the shaft 118. For charting a record, an adjustable electrical contact finger 235, Fig. 1, is provided on an arm 229, 230 pivoted at 232 on the tonearm carriage 117, The finger 235 is first brought against the tone - arm when this is in the starting groove of the record as shown in full lines in Fig. 1. The first section of the record is then played, during which the tone-arm moves away from the contact. The pointer 176 is then moved down the charting arm 175 to cause the contact 235 to move towards the tone-arm and again make contact with it. The position of the pointer 176 on the scale 171 then indicates the end of the section. Succeeding sections of the record are charted similarly. Contact between the finger 235 and the tone-arm is indicated by a lamp 236. The arm 229, 230 is made in two parts pivoted together, enabling the arm to be folded and swung out of action to the position indicated in dotted lines on Fig. 1. The casing of the apparatus is covered by a horizontal motor-board 9 and an inclined detachable cover plate 3, and contains a wireless receiving set 4, Figs. 2, 3 and 20, an amplifying unit 6, a rectifying unit 21, a loud-speaker 5, and a driving motor 20. The loud-speaker is suspended from the motorboard 9 in a compartment lined on four sides with one or more layers of cotton batting 14. The back opening 11 is covered by a screen 12 and cloth 13 in usual manner. The motorboard is also provided with openings 25 covered by cloth 26. The top of the casing has sockets 24 for detachable jacks connected to headphones. The optical - projecting apparatus, Figs. 22 and 23, comprises a lamp 280 with reflector 281 and a projecting lens system 282 between which is arranged an adjustable lantern slide 244 corresponding to the chart 168 but of a quarter its area. The slide 244 is adjustable vertically in a frame 241, and the frame is adjustable horizontally in a housing 237. The frame 241 is supported on rollers 248 and is attached by a bracket 274 to a belt 269 extending between pulleys 271 fast with pulleys 272 of twice the diameter over