US2323257A - Stepback mechanism for phonograph transcribers - Google Patents

Description

.June 29, 1943. L. THOMPSON ETAL STEPBACK MECHANISM FOR PHONOGRAPH TRANSCRIBERS Filed April 17, 1941 2 Sheets-Sheet 1 XNVENTORS Luwam Thompson Ro7)erIL.$.tor ze.

jkifM ATTORNEY June 2 19 3 L THQMPSN Em 2,323 7 S'I'EPBACK-MECHANISM FOR PHONOGRAPH TRANSGRIBERS Filed April 17, 1941 2 Sheets-Sheet 2 MOTOR l2 1 AMPLIFIER L I Q Jr ,v I

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ATTORNEY Patented June 29, 1943 JUNITED (STATES PATENT OFFICE Lincoln Thompson, Cheshire,

and Robert Leland Stone, Hamden, Conn., assignors to The Soundscriber Corporation, New Haven, *poration of Connecticut Conn, a cor- Application April 17, 1941, Serial No. 388,956

8 Claims- (01.274-14) This invention relates to improvements in mechanisms for sound reproduction and more particularly to a stepback mechanism for a transcribing machine employing disc records.

The present invention'is especially designed for dictating machines employing disc records of the type disclosed in Patent No. 2,200,866, issued May 14, 1940, to Lincoln Thompson, on an application filed December 15, 1938, Ser. No. 245,944, entitled "Disk dictating machine, and constitutes an improvement over the step-back mechanism disclosed in our copending application Ser. No. 248,691, filed December 31, 1938, entitled Transcribing machine," patented April ,29, 1941, No. 2,240,321.

In transcribing machines of theabove nature, it'is often desirable for the typist to play over a portion of the recorded dictation, and the present invention has for its principal object, the provision of an-improved form of solenoid-operated step-back" mechanism for back-spacing the pick-up needle a short distance over the record without raising the needle from or stopping the rotation of the turntable.

A further object is to provide means to brace the reproducing needle while the step-back action is taking place.

A further object is to provide a novel spring hinge connection between the pick-up unit and the arm carrying the same.

A still further object of this invention is to provide an improved form of step-back mechanism of the above nature which will be relatively inexpensive to manufacture, simple in construction, compact, ornamental in appearance, and very efiicient and durable in use.

With these and other objects in view, which will appear as the description proceeds, there has been illustrated in the accompanying drawings one form in which the invention may be conveniently embodied in practice. v

In the drawings:

Figure 1 is a perspective view of a transcribing machine embodying the features and principles of this invention.

Figure 2 is a top plan view on an enlarged scale of the improved step-back mechanism shown in cooperating relation with the reproducing pickup carrying member.

Figure 3 is a side view of the same, looking in the direction of arrow 3 of Figure 2.

Figure 4 is a front view 01' a portion of the step-back mechanism, looking in the direction of arrow 4 in Figure 2.

Figure 5 is-an enlarged fragmentary top view of a portion of the step-back mechanism illustrating by full and dotted lines three different operating positions of the same.

Figure 6 is a fragmentary side. view partly in section of the sound reproducing unit and its carrying arm, and showing the appearance of spring hinge joint therebetween.

Figure 7 is an end view of the same. c

Figure 8 is a schematic view of the invention including a diagram of the electrical circuits and control mechanism.

Referring now to the drawings wherein like reference numerals designate like parts throughout the several views, the numeral l0 denotes a casing over which a disc record supporting turntable it is adapted to' rotate. The turntable ii is arranged to be driven by an electric motor l2 (see Figure 8) Provision is made of an arm l3 (see Figures 1,

2, 6, and '7), carrying a sound' reproducing "pickup unit it, which is hingedly secured thereto by a flat leaf spring to, and also connected thereto by a coiled counter-balancing spring iii-said arm i3 being pivoted at II to the casing top l8 so as to swing over a thin disc record it carried by the turntable II. The pick-up unit [4 carries a reproducing needle 20 which rides in the sound track previously formed on the surface of the record N by a dictating machine (not shown) and vibrates said pick-up unit H, which is connected by conductors 2i and 22 to the input terminals of a vacuum tube amplifier 23 (see Figure 8). The output terminals of said amplifier 23 lead through conductors 24 and 25, to a loudspeaker or other sound reproducer, not shown.

As herein shown, the back-spacing or stepback means for the pick-up needle includes a fiat frame plate 26 (see Figures 2, 3, 4, and 5), which is adapted to be adjustably secured upon the casing E0, or to any other suitable stationary part of the transcriber, as by a screw 21 extending through an elongated inclined slot 28 formed in said frame 28.

Mounted on the frame 25 is an electromagnet which is surrounded by a wire coil 32. The mag-v t net 29 is pivotally secured to the frame member 26 by a vertical screw pin 33 which passes through the upper leg 3| and lower leg 34 of the core 30 at a point adjacent the curved base of said core.

The coil 32 is adapted to be energized by electric current from a pair of wires Li and L2 t ro gh conductors 35 and 36, underthe control of a switch 31, preferably hand or foot-operated. and located in circuit with said coil.

Provision is also made of a movable iron armature lever 33 of light weight which is pivoted to the end of the arm 3| as by a pin 33. The armature 38 is loosely mounted in aslot 48 provided in the free end of the leg 3|, whereby said armature will be supported against lateral movement, and will be carried by the electromagnetic core 38 when the latter swings on its screw pivot pin 33. The armature 33 extends a. short distance upwardly beyond the arm 3|, and carries onits outer face, adjacent its upper end a pointed lug or knife-edge 4| which is adapted to engage with a side bar 48 on the pick-up arm to be described later.

In order to limit the swinging movement of the armature 38 in a direction away from the leg 34, provision is made of a stop finger 42 bent upward- -ly from the frame 25 into position to be engaged.

by the lower end of said armature 38, when the core 38 is not magnetized. A coiled tension spring 43 is connectedat one end to a fixed angular post 44 preferably secured at one end to an upstanding ear 45 on the frame 23 by soldering, or brazing.. The other end of the-spring 43 is attached to the armature 38 at a point intermediate the upper and lower legs 3| and 34 of the core 38.

. The spring 43 thus serves to constantly urge the lower end of the armature 33 against the stop finger 42, and also acts to urge the electromagnet core 38 toward the upturned frame ear 45 and into contact with a horizontal adjustable stop screw 48 which is screw-threaded through said ear 45 and is locked thereto by a lock nut 41.,

The side bar 48 of the pick-up arm I3 is secured to said arm adjacent the rear end thereof as by rivets' and said side arm extends into the path of the upper end of the armature 38 so that whenever the electromagnetic core 38 is magnetized by current passing through the coil 32, the

knife-edge 4| will engage the curved edge 43 on the leg 34 of the core 38. The knife-edge 4| will thus engage the arcuate end of the side bar 48 with a biting action. Shortly, thereafter, the sluggish magnet core 38 will be caused to swing backwardly due to the attraction of a stationary iron post 58 which extends upwardly from the side of the frameplate 23 opposite to the side on which the stop screw 45 is disposed, The force due to the attraction between the legs 3| and 34 of the core 38 and the post 53 will cause the side bar 48 to back-space the pick-up arm any desired number of grooves according to the adjustment of the stop screw 48, it being understood that the needle will not be lifted from the record during this action.

The above described combined action of the armature 38 and the magnet core 38 is illustrated in Figure 5 wherein the initial position of the side bar 43 is shown in full lines, and its backspaced position in dotted lines. It will be understood that upon energization of the coil 32 to magnetize the core member 33, the leg. 34 of the magnet core 33 will attract the armature 33,

which being relatively light weight and low in inertia, will be quickly swung about the pivot 33, causing the sharp point 5| of the knife-edge 4|. to engage the curved end 43 of the thin side bar 48, as indicated at A in Figure 5. The relatively heavy core 38 will be slightly delayed in responding to the magnetic field but will be swung on its pivot screw 33 toward and against the armature post 58, as indicated in dotted lines at B in Figure 5, due to the magnetic attraction between the legs 3| and 34 of the core 38 and said iron post 58. The bar 43 will thus be caused to move from the full line position to the dotted line positions as shown in Figure 5. It will be clear from the above explanation that the knife-edge 4| gaging the edge of the side bar 48, and then mov-- ing laterally with said side bar through the desired amount of back-spacing.

After the switch 31 is opened the armature 38 will be released from the magnetic attraction of the core 38 and will swing quickly due to the action of the spring 43 back into contact with the lug 42. The core 38 will then swing more'sluggishly back to its original full line position, shown in Figure 5 in contact with the stop screw 43.

In order to brace and support the needle 28 against being bent when the pick-up I4 is stepped-back by the mechanism above described, provision is made of an angle block 52 secured to the underside of said pick-up, Just behind the needle 28 (see Figure 7). The block 52 has a vertical arm 53 which is disposed closely adjacent to the reproducing needle 28, but not so close asto interfere with the normal vibrations thereof.

The picln-up used for the transcriber mechanism herein disclosed, should preferably be of the type disclosed in Patent No. 2,213,936, issued to Lincoln Thompson, wherein the needle movement is extremely flexible, the brace 52 being essential in order that the movements of the reproducer arm I3 should be transmitted to the needle 28 without excessive backlash, and yet permitting said needle to execute its normal'vlbratlons without striking said brace 52. A further advantage of the use of the brace 52 is that the depending leg 53 will positively jar and vibrate the needle at each actuation so that it will never come to rest on the flat land between two adjacent grooves. I

Operation In operation, whenever the typist listening to the loudspeaker reproduction of the record l3 in response to the pick-up l4 desires to replay any desired portion of the record, it will only be necessary when this portion has been played to manually close the switch 31, which will be placed in a readily accessible position. The closing of.

the switch 31 will energize the 'coil 32, and thus magnetize the core 38, whereupon the light armature 38 will be quickly moved into engagement with the side arm 48. The heavy magnet core 38 will be more slowly swung about its pivot 33 and the combined action of the armature and core will cause the pick-up needle 28 to slide back over the record the determined number of grooves. If a greater number of grooves are to be replayed, the switch may be actuated two or more times in succession.

One advantage of the use of the flat leaf spring |5 to connect the arm I 3 and pick-up I4, is that side play therebetween is almost entirely avoided, which is of utmost importance in producing an accurate and uniform amount of back-spacing every time the step-back mechanism is operated. This leaf spring also permits a pick-up head of such as cotton, within the spirit and scope of the invention.

It will be understood that the step-back operation of the clapper 38 and the core 19 may be diiferentially-v adjusted by changing the air gap between the end of the clapper 38 and the mem-' ber 42, as well as the air gap between the post and the core 30. The tension and position of the spring 63 may also be changed if desired. The time and speed of each separate motion may thus be accurately controlled to produce any desired sound record to be transcribed, an engagement member carried by said reproducer arm, electromagnetically-operated means to engage said' member and move said arm rearwardly to stepback said needle a predetermined number of grooves, said means'inciuding a fixed iron post and a pivotally mounted slowly movable sluggish core of magnetic material having a high moment oi inertia located adjacent said post and adapted when magnetized to beattracted to said post, a

solenoid coil for magnetizing said core, a rapidly movable light weight armature pivoted to and attracted by said core when the latter is energized, said armature having a knife-edge for engaging said member to clutch it rapidly and cause it thereafter to be moved rearwardly relatively slowly withtsaid core, and spring means resultant effect. It will also be understood that the spring 33 may, if desired, be replaced by two separate springs at right angles to each other within the scope of the invention.

While there has been disclosed in this Specification one form in which the invention may be embodied, it is to be understood that this form is shown for the purpose of illustration only, and that the invention is not to be limited to the specific disclosure, but may be modified and embodied in various other forms without departing from its spirit. In short, the invention includes all the modifications and embodiments coming within the scope of the following claims.

Having thus fully described the invention, what is claimed as new and for which it is desired to secure Letters Patent, is: r

1. In a phonograph transcriber, a reproducer arm carrying a pick-up needle mounted to move with respect to the surface of a rotating disc record to be transcribed, a cam connected to said reproducer arm, and electromagnetically-operated means to engage said cam and move said reproducer arm rearwardly to step-back said needle a predetermined number of grooves without removing said needle from the surface of said record, said electromagnetically-operated means including a pivotally mounted slowly movable core of magnetic material and having a relatively high moment of inertia, a fixed iron post, a solenoid coil for magnetizing said core and causing said core to move toward said post, and a rapidly movable armature attracted by said core and having a knife edge engagement with said cam to clutch the latter and cause it to be moved rearwardly slowly with said core.

2. In a phonograph transcriber, a reproducer arm carrying a pick-up needle mounted to move with respect to the surface of a rotating disc record to be transcribed, a cam connected to said reproducer arm, electromagnetically-operated means to engage said cam and move said reproducer arm rearwardly to step-back said needle a predetermined number of grooves without removing said needle from the surface of said record, said electromagnetically-operated means including a pivotally mounted sluggish core of magnetic material and having a high moment of inertia, a fixed iron post, a solenoid coil formagnetizing said core and causing said core to move toward said post, and a rapidly movable armature pivoted to and attracted by said core. and having a knife-edge engagement with said cam to clutch the latter and cause it to be moved rearwardly slowly with said core.

3. In a phonograph transcriber, a reproducer arm carrying a pickup needle mounted to move a rotating disc record, a fixed casing, said arm a to restore said armature and said core to their inactive initial positions whenthe magnetic flux is removed.

d. In a phonograph transcriber, a reproducer arm carrying a pickup needle mounted to swing with respect to a rotating disc record, said reproducer arm having a cam surface, a slowlymovable sluggish iron core having a solenoid coil mounted thereon, a rapidly-movable iron clutch.

lever pivoted to said core, a fixed armature post for attracting said core when said coil is energized, said, clutch lever being more rapidly attracted by said core than said core is attracted by said post, whereby said cam surface will first be engaged by said clutch lever and thereafter moved more slowly by the swinging of said core to stepback said needle slowly a predetermined number oi grooves, the axes of the pivots of said letilrlerand said core being at right angles to each 0 er.-

5. In a phonograph transcriber oi the type having a pivoted reproducing arm carrying a pickup needle which is mounted to swing across having a side extension provided with a cam edge concentric with the axis of said pivoted arm, a

, sluggish slow moving iron core pivotally mounted on said casing, an iron armature post fixed to said casing and adapted to attract said core when the latter is magnetized, a rapidly moving iron clutch clapper pivoted to said core and located in alignment with said cam edge, an electromagnetic coil surrounding said core for energizing it and causing said clutch clapper to swing quickly into engagement with said cam edge and thereafter cause said core and clapper to slowly move said arm to step-back said determined number of grooves.

, d. In a phonograph transcriber, a casing, a disc record mounted to rotate on said casing, a pickup-carrying reproducer arm pivotally mounted to swing over said record, said arm having a side extension provided with a curved cam edge concentric with'the pivotal axis of said arm, a relatively heavy sluggish iron core pivoted to said casing, a fixed iron post mounted on said casing and adapted to attract said core when the latter is magnetized, a relatively light iron clutch member pivoted to said core, an electromagnetic-coil surrounding said core for magnetwith respect to the surface of a rotating grooved izing it and causing said clutch member to move rapidly into contact with said side extension, and to thereafter cause said core and the clutch member carried thereby to move more slowly to step-back said needle a of grooves.

7. In a phonograph transcriber. a reproducer arm carrying a pickup needle mounted to swing pickup needle a pre-- predetermined number over a rotating disc record, said arm having a laterally extending cam surface, a slowly-movable sluggish iron core having a solenoid coil mounted thereon, a stationary iron post for attracting said .core when said coil is energized, a

rapidly-movable iron clutch lever pivoted to said core and adapted to be operated thereby, said lever having a knife-edge located in alignment with said cam surface, whereby when said coil is electrically energized said lever will be caused to clutch said cam surface quickly and thereafter to slowly step-back said needle-carrying arm across said record a predetermined number of grooves.

8. In a phonograph transcriber, a pivoted reproducer arm carrying an electric pick-up needle, said arm being mounted to swing with respect to the surface of a rotating grooved sound record to be transcribed, a lateral extension member carried by said arm and having an engagement surface, amovably mounted clutch. member in alignment with said" engagement surface, and means to cause said clutch member to move in a substantially square path in four successive steps from a starting position, including means LINCOLN THOMPSON. ROBERT L. STONE.

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