US2318183A - Portable phonograph - Google Patents

Description

May 4, 1943. I VB. ROBERVTS 7 2,318,183

4 PORTABLE PHONOGRAPH Filed Nov, 1]. 1941 s Sheets-Sheet 1 BEucE Joasezg- Q v I I INVEVNTOI? 4 /l BY .Arromvev.

May 4; 1943. B. ROBERTS PORTABLEQPHONOGRAPH Filed Nov. 1, 1941 3 Sheets-Sheet 2 I 4 2 m 5 7 4 m z W. v w

....I it

.BeucsRoaser INVEN'I'OR ATTORNEY.

Patented May 4,1943

PORTABLE mono'cnarn Bruce Roberts, Los names, CaliL, assignor. by

mesne assignments, to Radio Corporation of Americana corporation of Delaware Application November 1, 1 9;4l, Serial.No. 417,436 -14 Claims (cl.1'z9'-1oo.4)

gle combination 1 rectifier amplifier tube, although it is to be understood-that otheracircuits This invention relates to sound reproducin apparatus and particularly to a portable type of disc phonograph wherein the complete motor mechanism and reproducing apparatus are contained within small dimensions. g s Portable types of radios and phonographs are well known in the art, the present invention being may ,be employed to provide greater .ampliflca -tion, if desired.

The principal object ofthe invention, therefore, is to facilitate the reproduction of disc-type phonograph records.

of that general type butembodying features which permit the unit to be of a particularly small size. The unit also embodies features which provide a quality of'reproductionat least as good as, if not better than, that obtainable with thelarger Portables. p

. One of these features is the. arrangement of the pickup carriage so' thatthevneedle'has a Another objector the invention is increase the portability of afdisc-record phonograph.

Aiurther object of the invention is to provide a pickup unit for aphonograph which will travel substantially along a radius substantially constant or fixed angle of contact.

with the record groove regardless of-its position along. the groove. It is well known "that 'mostrecords are cut with a stylus that travels along a radius of the record. In present types of phonographs, however, the'pickup unit is mounted on an arm pivoted at one end so that the angle of the needle with respect to therecord groove varies as the needle travels along the .groove, which means that the pickup needle does not follow the same radius as the cuttingstylus, but follows an are along the radius. This-is conducive to excessive wear on the record and needle. in the present invention the. pickup unit follows substantially along the radius of a record inthe same manner as the recording stylus.

Another feature of the invention is the automatic switching arrangement controlled by the the unit;

A further object of the invention is to provide automatic control of the starting and stopping. of the phonograph motor bythe pickup carriage.

Although, the novel features which are believed to be characteristic of this invention will be pointed out with particularity in the "appended claims, the manner of its organization and the mode of its operation will bebetter understood by referring to the following description read in conjunction with. the accompanying drawings forming a part thereof, in which K 1 Fig. 1 is aperspective view of the'inventlon with a record inplaying position:

.Fig. 1A

ri 2 is a plan view or the invention;

Fig; 3 is a cross-sectional view taken alongthe line 3 3'of Fig. 2;

Fig. 4 is a cross-sectional view taken along.

the line 4-4 of Fig. 3;

pickup'carriage when at each end of its pathuof travel. That is, the carriage disconnects the motor switch when in itsoutside terminal position so that-the records may be placed on and. taken off the turntable, while the motor isautomatically disconnected when the record-groove bringsthe pickup to its inner terminal position. "At' intermediate positions or the swltch is closed to energize the mute the pickup'heedle with respect to the record. -1 Contrary tothe usual practice of havingthe pickup above the .record-,-the'pickup .is placed below and the needle is resiliently held-in the groove by spring tension .which permits a li ht,

constant, predetermined pressureto berobtained. The motor is preferably oii'the' vertical-shalt typepperating through a plurality of resiliently mounted pucks to a flanged, small-diameter;-

turntable; The pickup maybe of the magnetic or crystal type, the latter being preferred, while, the electrical reproduction is providedby asin;

Dickup,- the Fig. 5 is a plan'view taken along the line 5.-5 of Fig. 3;

Fig. 6 is a planview of the carriage and pickup unitof the invention;

' Fig. '7 is a detail view oi the motor switch; and

is a schematic drawing of the reproducing circuit of the invention.

Referring now to the. drawings inwhich identical -numerals'identiiy like elements, acasing' 5 p s of any suitable material is shown with an open- Another feature-is the manner of positioninging 6 covered by a decorative fabric 1 behind which is located the speaker unit or the phonograph. fihe case has a cover section 8, as shown in Fig. gm, the. cover having a handle in and clip locks at the ends thereof, as shown at. H and i2. :An'openiug at one end of the case I is provided for the insertion-pi an electrical supply connection [4. As shown in Figs. '2 and 3, a screened-air vent is provided at ii to provide ventilation for the cool i f he int rior of the I phonographrnechanismf- Slifllclent room is pro- .vided under the 'vent' ii to accommodate the connecting supply cord l8.

of the'record.

is a perspective View of the cover for n angle .platc i8, fastened by'screws such as hand p si pplne .of a p n 1 th Referring'now particularly to Figs. 2, 3 and 4, the record groove brings the pickup to its leftg l I! to the case I, has a motor 18 suspended thereblade 6| below blade 80, as shown in Fig. 'I, perr from on resiliently mounted posts 20. The shaft mits the switch to function in this manner.

28 of the motor has mounted at its lower end The arrangement of the electrical reproducing a fan 24, while the upper end of the shaft conelements is shown in Figs. 3. 4 an AS m ntacts a puck 25" which rotates a smaller puck tioned above, the plate It supports the motor 28 on a shaftl'l, the upper end of shaft 21 being and a cable comprising three conductors, two of supported on a bracket 28 (see Fig. 4). The which go to the motor l8 and the switch blades smaller puck 28 is adapted to contact the inner 1o 68 and GI, and the other of which goes to the circumference of a flanged turntable 30, the pickup, the latter being shown at 85. These turntable having a shaft 8| rotatable in a bearthree conductors are in the cable 66 and termi- 'ing sleeve 32 and'maintained in the sleeve by nate in aconnecting plug 81. Thus, the removal a screw 88. a of the plug 61 from its socket 68 permits the The turntable comprises an inner metallic secturntable, motorcarriage and pickup to be re- .tlon 88. which contacts the puck 28, and a cover moved as a unit from the case 5. When these section 88, preferably of rubber or other similar elements are replaced in the case, the plug 81 is material. :The turntable has a spindle 88, the connected in the socket .68 and the circuit is comupper end of which has spring-tensioned dogs 38 pleted.

and 48 mounted therein for holding a disc record As shown in Figs. 3 and 4, an angle bracket 88 42 onthe turntable when pressed on the spindle. serves as a bottom for the case and as a'mount- A The edges of the dogs, are tapered so that the ing for the electrical elements of the reproducing record may be placed on .and removed from the circuit, such as'a transformer 10, a connecting turntable by a slight pressure on the rim of the plug socket II, and a potentiometer 12 with its record, while the tension is suiflcient to mainhand wheel I3, the latter beingfree to rotate tain the record firmly against the upper side of since the plate 69' is supported upon legs 15.

the turntable during reproduction of the record. Also mounted on the lower portion of the angle The diameter ofthe tumtableiswithin the groove bracket 88 are the various resistance and conarea of the .record and may be appreciatedby denser elements such as shown in Fig. 8 at 11, 18, comparing it with the diameter 'of a ten-inch I9, 88, 8|, 82, 88, 84, 85 and 88, while the loudrecord, the circumference of whichis shown by speaker 81 and combination rectifier-amplifier .the broken line in Fig. 2. tube 88 are mounted on the upper portion of From the above description, it will be obthe bracket 69. Thus, the electrical elements atserved that rotation of the motor shaft 23 will tached to the bracket 89 are exposed by removal transfer motion through the pucks 25 and 28 to 5 of the bracket 89 from the bottom of the case 8 the turntable 88, thus rotating the record 42. after removal of the screws 89. In this manner Reproduction of the record is obtained by the this portion of the system' may be readily reuse of a pickup 44 having a handle 68 and a needle moved as a unit for inspection or repair.

48 adapted to contact the spiral groove on the Referring now to the electrical circuit as shown underside of the record 42. The pickup is in Fig. 8, it will 'be observed that the power is "mounted on the horizontalportion of an angle supplied over a switch 9| which may be op,-

rod 48 attached to a U-shaped rod carriage 48 erated in conjunction with the gain control pohaving switch control pins 48 and 58 and a stop tentiometer 12. The closing of this switch will pin "on arm 58 thereof. The needle 45 is mainenergize the tube, 88, while the position of the tained at a predetermined pressure against the 45 pickup 44 determines whether or' not the switch record 48 by a coil spring 52 around the horlblades 68 and 8| connect the motor I, to the 'zoniial portion. (iii-the pickup support, and a power source forrotating the turntable 30, as hearing against the pickup unit (see Fig. 6). The explained above. The output of the pickup 44 is carriage 48; is adapted to translate the pickup controlled by potentiometer I2 and is impressed needle 48 along a straight line substantially ooupon the grid of tube 88, this tube being a comincident with a radius of the record 42 by being "bination rectifier-amplifier and preferably of the mounted on three rollers, a roller 84 supporting type known as RCA '70L7GT. The output of the the undersidelof-section 58 of the carriage 48, a amplifier stage is transmitted through transroller 88 supportingthe underside ofsection 81 former I0 to the loudspeaker 81. The field coil of the carriage '48,'while a roller 58 bears against 82 of the speaker 81 and the condenser 85 provide the upperside'of section 51 of the carriage. the filtering of the rectified output for the, am-

' Thus, the carriage is mounted on athree-point -plifler anode of tube". through'resistance I8, roller suspension which provides the minimum whilethe proper potential isimpressed upon the 7 load nthe needle. and EIOOVB'tO permit the pickscreen grid of the amplifier stage over resistup dl to follow the groove in the record while ance I'I. Gridbias for the amplifier stage is obaintaining su antially the same angle of contained over resistance" by-passed-by condenser tact with the groove at all times. 88, while the resistance 8| and condenser 82 dis- Referrlng now to Figs. 5, 6, 'l and 8, azpair charge the condensers after ,the power is disof switch blades 80 and" are in the motorcirconnected from the system. The resistance 19 cult, the pin 48 moving blade I to the right, 5 provides the proper voltage for the heater elebreaking the motor circuit when the pickup 44 is ments of the tube, while condensers 84 and 86 are at its extremev right-hand'position, as shown inby-pass condensers.

Fig.5, while the pin 80 moves blade at to the left, From the above, a is observed that the unit is breaking the motor circuit when the pickup 441s made particularly compact by segregating the moved to its left-hand position by the groove in motor portion from the electrical portion, which the record or m uaflm'as shown; Fi 6, Thus, permits the dimensions of the entire unit to be.

the position of the carriage 48 controls the 1110- less than the dimensions of a record to be played. torcircuit, the. circuit-being opened when the In the usual type or small unit, quality lggens' ickup 44 is moved by its handle 88' to its righterally sacrificed to obtain the small dimensions, mndpositi'on, and the circuit being opened when but in the present arrangement. high quality reasiaiea production is also obtained. The mounting of the-pickup unit is such that it may be operated outside the dimensions of the case, while vits movement is substantially along a radius of the record providing a constant angular relationship between the groove and the needle. The pickup may be provided with any predetermined tension desirable for high quality reproduction and long circuit for opening and closing .said energizing tached thereto means for reproducing said record.

life of the record. The position of the pickup controls the starting and stopping of the turntable automatically. Thus, the combination. ofthese features provides a high quality portable phonograph. Although the above invention has a been disclosed in connection with a power-operated circuit, it is realized that the reproducing system may be battery-operated and the tumtable spring-driven, as is well known in the art;

What I claim as my invention is:

1. In a phonograph mechanism the combination of a turntable, a spindle, means for holding a record on said turntable, a carriage rectilinearly movable under said turntable, and a pickup unit mounted on said carriage, the stylus of said pickup beingadapted to contact the groove in .the underside of saidrecord for moving said pickup substantially along a radius of said record.

' 2. A combination in accordance with claim 1 in which said pickup is resiliently mqimted and adapted to reproduce the underside of said record.

3. A combination in accordance with claim 1 in which said means for holding said record on said turntable includes a pair of dogs resiliently mounted in diametrically positioned grooves in said spindle. I

4. A phonographcomprisin'g a vertical shaft motor, a turntablemounted above said motor,

carriage being adapted to open said switchat each terminal position of said carriage.

6. A phonograph comprising a casing, a motor, a turntable, a pickup, a carriage for said pickup, a bracket for mounting said elements, said motor being positioned within said casing, and said carriage and pickup-being adapted to move beyond the external boundaries of said casing, an energizing circuit for said motor, a switch in said circuit, and means onsaid carriage for automaticalLv opening said 'switch' at either of the terminal positions of said carriage.

' 'L- A phonograph in accordance with claim 6 in which said casing is provided with a detachable bottom member, said member having at- 8. 'A phonograph in accordance with claim 6 in which a pickupis mounted on said carriage for translating a record into electrical currents, an electrical amplifier and loudspeaker are provided in said'casing for amplifying and translatin whichsaid carriage is U'- shaped and adapted mg said electrical currents into sound waves, and a detachable bottomis provided for said casing on which said amplifier and loudspeaker are mounted.

9. A phonograph comprising a casing, a

bracket at the top of said casing, a motor sus pended from said bracket, a turntable mounted on top of said bracket, a carriage positioned in- 'termediate said motor and said turntable and adapted to move rectilinearly, a pickup at one end of said carriage, and means for holding .a record on said turntable, said turntable having a diameter less than the smallest diameter of the groovedpprtion of said record. i

10. A phonograph in accordance with claim 9 in which means are provided at theother end of said carriage forcontrolling the energizing of said motor. s

11. A phonograph in accordance with c1aim 9 "in which are provided an energizing circuit for .said motor, aiswitch 'in said circuit, and means on said carriage for controlling the openingfland closing of said switch.

12. A phonograph in accordance with-claim 9 to be moved rectilinearly on rollers, said pickup being mounted at the closed'end of saidcarriage.

13. A phonograph for reproducing a disc record comprising a turntable having a diameter less than the grooved portion of said record-a motor for rotating said turntable, a carriage adapted to be ,moved 'rectilinearly and substantially coincident with a radius of said record when on said turntable, and a pickup unit mounted on said carriage and having a stylus adapted to contact the grooved underside'of said record, rotation of said record moving said pickup substantially along a radius of 'said record.

14. A phonograph in accordance with claim 13 in which means are provided on said. carriage for controlling-the energization of saidmotor,

said motor being'deenergized at each terminal position of said carriage. v

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