US2452133A - Phonographic apparatus - Google Patents

Description

Oct. 26, 1948. G. LElTNiER ETAL 3 3 PHONOGRAPHIC APPARATUS Filed Sept. 18, 1942 2 Sheets-Sheet 1 72 RICHARD G. -LEITNER WILL/AM K R/EBER ATTORNEY I A 0 I 5 I v 1 INVENTORS;

R. e. LEITNER ETAL 2,452,133

PHONOGRAPHIC APPARATUS Get. 26, 1948.

2 Sheets-Sheet 2 Filed Sept. 18, 1942 RICHARD a. LE/TNER E B WILL/AM K R/EBER ATTORNEY Patented Oct. 26, 1948 PHONOGRAPHIC APPARATUS Richard G. Leitner and William K. Richer, West Los Angeles, Calif., assignors, by mesne assignments, to Dictaphone Corporation, New York, N. Y., a corporation of New York Application September 18, 1942, Serial No. 458,777

3 Claims. 1

Our invention relates generally to phonographic apparatus in which sound is recorded on and subsequently reproduced from a record made of suitable material.

An object of our invention is to provide a phonographic apparatus for the reproduction of sound in which back spacing, or repetition of the portion of the record last played may be accomplished readily and by simple means.

A further object of our invention is to provide vmeans by which the amount of back spacing or the extent of repeated material may be varied at the will of the operator.

Another object of our invention is to provide an apparatus for reproducing sound in which the speed of reproduction may be conveniently adfrom the following disclosure.

In the past, a majority of all stenographic Work in which recorders have been employed has been,

done by the use of cylindrical records, of 'such dimensions, and operating at such speeds that only a relatively small amount of recorded mate- .rial is reproduced from each turn of the cylinder. Consequently, back spacing in such a device can be conveniently accomplished by merely shifting the reproducing stylus into the next previous groove. If a greater quantity of back space is required, a shift of two or more grooves may be used.

Disc recording is preferable in many ways to recording on cylinders, but due to the customary dimensions and rate of rotation of such discs, a shift of the reproducing stylus from one groove into the next preceding groove will produce a greater back spacing than is normally required. This is particularly true in the case of recorders in which the rotary speed of the disc has been reduced to a minimum consistent With the production of good articulation.

Because of its many advantages, we prefer to use a disc type phonograph in which the disc is not only driven very slowly, but is driven at a constant groove speed at all times. Using such a drive and a 12" record disc, the elapsed time per revolution, at the outside of the edge, may

be as much as nine seconds.

Average working values for back spaced time in ordinary phonograph work will vary from less than one second to over three seconds, intervals longer than this being seldom required.

By the use of our invention we are able to accomplish the required back spacing by reversing the direction of rotation of the phonograph, this reversal being conveniently under the control of the operator, who after a little practice can determine the required duration of reversal with a high degree of accuracy.

During the reversed operation of the apparatus, sound reproduction may be accomplished or discontinued at the will of the operator. Although sounds played in the reverse direction are naturally unintelligible, the operator may derive considerable help in determining the required back spacing by noting the number of syllables contained in the reverse playing. Particularly in this connection, the beginnings of sentences or phrases may be located with great accuracy by listening to the reversed play back.

We are aware that it is common practice in sound studios, where disc records are used, for the operator to place the needle in the, groove and run the turn table backwards by hand while listening to the reversed sound until the beginning of some sentence or phrase is located, so thatthe turn table in starting up may begin accurately at some predetermined point in the recorded sound. However, so far as we are aware, no one has heretofore produced a practical or efficient means of backspacing a record by the reversal thereof, and it is the solution of this problem to which our invention is particularly directed.

Referring now to the drawings:

Fig. 1 is a top plan view partially cut away of a preferred form of our device,

Fig. 2 is a front elevation of the same,

Fig. 3 is a wiring diagram, and

Fig. 4 is an end elevation.

In the form of our invention herein illustrated, the operative parts may be supported in any convenient framework, such for example as that illustrated herein, where the numerals Ill and II designate vertical end posts and the numerals l2 and i3 indicate side frames of suitable design.

ted to slide freely on the rear way l5, while the front bar 4'5 of the carriage is supported by a roller 2| which rides on forward way ll.

Rotatably mounted in a vertical housing 22 adjacent the rear of the frame is a spindle 23 carrying a supporting flange 24 to which is fastened a turntable 25 adapted to receive a disc record 26. The lower end of the spindle 23 is geared to a screw threaded horizontal shaft 21 journaled in the side brackets l2 and I3 as shown, so that rotation of the spindle causes rotation of the shaft 21. At substantially its midpoint where it is stiffened by crossbrace 23', the carriage 6 is provided with a pair of depending arms 29 and 30 which carry a horizontal shaft 3| in their lower ends. An opened L -shaped member which we will hereinafter term the follower 32 is provided with a half-nut at its elbow adapted to engage and mesh with the threads on shaft 21. The upper end of the follower 32 is pivoted on the shaft 3| so that it can be swung into engagement with shaft 21, in which position it is normally retained by a coil spring 33 attached to its rear and lower end. A suitable sound reproducing head 34 including a stylus 35 is mounted on the carriage 6 in con venient manner as by means of a goose-neck 36 disposed so that the recording head will normally be suspended above the turntable 25 in position for the stylus 35 to operate on the disc 26.

Pivoted on the shaft 3| is a plate 31 having a tubular bearing 38 formed therein in which is journaled a shaft 39 carrying a pulley 40 on one end thereof and a friction driving wheel 4| on the other end. The wheel 4| is adapted to engage the under face of the turntable 25 to rotate the same in conventional manner, and is releasably held in engagement with the turntable, by

resilient means such as the compression spring 42 which seats on a bracket 43 on the rear end of the carriage l6. 7

It is thus seen that rotation of the pulley 40 rotates the friction driving wheel 4| which in turn operates the turntable 25 to rotate the rec-.. rd 26. Likewise, rotation of the turntable spin dle 23 rotates the shaft 21', which by reason of its engagement with follower 32 moves the carriage and its associated mechanism horizontally toward or away from the turntable.

It is sometimes desirable to disengage the driving wheel 4|, follower 32 and sound head 34 all at once. To accomplish this with a minimum of effort, we provide a rod 44 journalled in bosses 45 and 46 on gooseneck 36 and connectedto the top of sound head 34 in such manner that rota-' tion of the rod 44 will raise the head up'out of its normal position in engagement with disc 26. At its outer end the rod 44 may be provided with a knob 41 adapted to engage a vertical rod 48 connected at its lower end to a crank arm 49 fast to a horizontal shaft 50. The other end of the shaft 50 has 3, depending arm attached thereto, the lower end of which engages'a pin 52 carried on the lower central portion of follower 32.

Rotation of the knob 41 besides raising the head 34 out of engagement withrecord 26, also moves rod 48 downwardly. wh ch depresses the The rotation of shaft 50 swings 4 per end bent at 54 to hook over the rear end of the plate 31. Consequently, downward movement of the follower 32 causes the rod 53 to rotate the plate 31 downwardly about its pivot shaft 5| to disengage the friction wheel 4| from turntable 25.

From the foregoing it will be seen that although the pulley 4D is rotated at a constant speed, the turntable may be driven at a progressively decreasing angular speed as the stylus moves away from the center of the record, thus producing a constant linear speed for the disc with respect to the stylus. It is usually advisable for the pulley 40 to be driven at a constant speed, and to accomplish this in a simple and efficient manner we provide the mechanism now to be described in detail.

Journaled in brackets 55 and 56 on side frame l3 and post M respectively, is an axially slidable shaft 51 which has a pair of spaced discs 58 and 59 fast thereto and rotatable therewith. Disposed to one side of the discs 58 and 59 is an electric motor 60 whose drive shaft 6| extends between discs 58 and 59 and is provided with a small friction wheel or driving head 62 slightly less in diameter than the space between said discs so that it can engage either but not both of said discs at the same time. It will be apparent that when the driving head 62 engages disc 58, the shaft 51 will rotate in one direction (forwardly in this embodiment of our invention) and when the head engages the disc 59, the shaft 5! will be reversed. Suitable means such as a leaf spring 53 may be provided at the rear end of the shaft 51 to urge it forwardly and hold disc 58 in normal driving engagement with the friction wheel 62.

Rotatably mounted on the rear portion of the shaft 51 is a pulley 64 which is provided with a horizontally extending pin 65 parallel to shaft 5! and adapted to be engaged by a radial lug 66 on shaft 51. Consequently, rotation of shaft 51 will rotate pulley 64 when, but not until, lug 66 engages pin 55, so that upon reversal of the shaft 51 there will be a short time interval, while the shaft is making its first reverse rotation, before the pulley 64 is reversed. This is extremely beneficial for rapid changes of direction, since it prevents oscillation of the pulley, and also gives the motor a chance to get up speed before taking its load,

The pulley 54 carries a looped belt 6'! which extends around a pulley 68 rotatably mounted on the side frame I 2, thence around a pulley 69 mounted on carriage I'6, up around pulley 40, back down around another pulley 73 on the carriage, and thence back to main drive pulley 64. As clearly seen in Figs. 1 and 2, the peripheries of pulleys 59 and 16 are substantially tangential to a line tangent to the peripheries of pulleys 64 and 68, i. e. to what would be the normal path of the belt if it did not pass over pulleys 69 and T6. In their other plane, the peripheries of pulleys 69 and Til are substantially aligned with the plane of pulley 40 so that the belt 61 can be easily looped over the latter. By thus disposing the pulley 69 and Hi, the carriage |6 can be moved in either direction without affecting the tension or alignment of the belt since the normal course of the belt is relatively unaffected. Thus, it becomes possible to efficiently drive the turntable through a movable carriage from a stationary motor and main drive shaft, which is a distinct advantage and advance over the prior art in this field.

"80 fastened to the base .of the frame.

As previously mentioned, one of the major objects of our invention is to provide suitable back-spacing means for sound reproducing apparatus. Our preferred method of accomplishing this back spacing is to reverse the record for the required time without removing the stylus from its operating position. In the form of our invention illustrated herein, we provide an electromagnet H whose armature I3 is connected to warm 14 of a bell crank whose other arm bears against the forward end of drive shaft 51. The electromagnet is supported by any convenient means such as bracket 12, and the bell crank is preferably pivoted at its fulcrum on a post 16. It will be apparent that when the electromagnet H is energized, its armature 13 will pull the crank arm 14 inwardly, causing the other crank arm 15 to push the axially slidable shaft 51 rearwardly until the disc 59 engages the friction driving head 62 of the motor. As previously explained, this immediately reverses the shaft 51, which reverses the turntable as soon as lug 66 makes one revolution to engage the other face of pin 65 carried by drive pulley 64. By keeping the electromagnet circuit closed the required interval of time, the

disc 26 is reversed the correct amount for the cut back in circuit as soon as the reversing magnet H is deenergized.

We have also found that for most commercial installations it is advisable to have the record 26 automatically backspaced a slight amount when ever the record stops .so that the last few words will be played back when the record is started up again. As our preferred means of accomplishing this automatic backspacing, we provide a mercury switch Tl supported on an arm 18 pivoted on a stub shaft .19 mounted in an upstanding bracket Rotatably mounted on the stub shaft 19 is a pulley 8| provided with an outwardlyextending pin 82 adapted to engage the arm 18 upon rotation of the pulley. The bracket 80 is disposed so that belt 61 passes over pulley BI and causes it to rotate if it is free. However, if the pulley is locked against rotation, the belt merely slips over the pulley groove until such time as the pulley is freed.

In the embodiment illustrated in the drawings, the belt 6! runs in the direction of the arrows in Fig. 2 when the machine is playing. Thus normal forward movement of the belt rotates the pulley clockwise in Fig. 2, causing the pin 82 to engage arm 18 and swing the switch 11 to the right, until the arm strikes stop 83 which limits its rightward movement. The switch T! is installed so that it is closed when in its extreme rightward position. When the direction of the belt travel is reversed, the pulley 8| being free to rotate in a counterclockwise direction is rotated by the belt until the pin 82 has traveled around to engage the other side of arm 18, whereupon further rotation of the pulley swings the arm to the left until it reaches the position shown in the drawing where it is resting against the stop 84. In this position the switch 11 is open.

Referring now to the wiring diagram in Fig. 3, it will be seen that in our preferred apparatus the motor 60 is connected directly across the mains through-"a single pole doubleithrow switch having a movable arm 'a'nd contacts 86 and 81. When the switch :arm 85"; is pressed down into engagement'with contact 81 the-motor circuit is closed and the shaft 57 rotates forwardly. This causes belt '6! to rotate pulley '8! which closes mercury switch l'l which is in parallel with the switch'arm 85. Consequently, the motor will continue to run even though the connection between switch arm 85 and contact 81 is broken, so long as switch l'l remains closed.

Switch ll is also in series with the'electromag net ll through contact 85 so that when switch arm 35 is moved upwardly into engagement with contact 86 and switch H is closed (as it always is when the machine is playing) the electromagnet ll will be energized to reverse the machine and disconnect the'sound head. *The switch arm is preferably provided'witn a spring (not shown) which holds it normally open and in engagement with Contact 86. 1

Reversal of the belt M, of course rotates pulley 8| backwardly to open switch Tl after one complete rotation of the pulley 8i, which breaks the electromagnet' circuitand allows the shaft 5'! to return to its forwardly operating position. However, since the switch arm 85 is open, the motor circuit is also broken and the machine comes to rest. By properly adjusting the size of pulley 8i and the driving connection between it and. switch ll, the time during which the machine is automatically reversedmay of course be varied to'suit all needs.

If it is desired to backspace the machine more than the smallamount resulting from merely releasing the switch arm 85, the'switch 8 8 which is in serieswith the ele-ctr'omagnet 7! and in parallel with mercury switch ll may be closed. Thus with switch arm 85 in its normally open position in engagement with contact tidithe closing of switch 88 the reversal circuit as is donebyswitch 88. However, in the interest of simplicity, we have shown two switches for accomplishing these changes.

From the foregoing it is seen that we have provided a simple and efficient drive and backspacing means for phonographic apparatus. It will be understood, of course, that while the particular form of our invention shown and described herein is fully capable of attaining the objects and providing the advantages stated, it is merely illustrative of the broad principles of our invention as set forth in the appended claims, and that other embodiments are contemplated.

We claim:

1. In phonographic apparatus of the character described, the combination of: a frame having mounted thereon a turntable and a carriage movable radially of said turntable; a sound reproducing head mounted on said carriage and adapted to engage a disc on said turntable to reproduce sound therefrom, a friction wheel on said carriage engaging said turntable and adapted to frictionally drive the same; a screw shaft geared to the shaft of said turntable; means on said carriage for engaging said screw shaft so that rotation thereof moves said carriage on its ways; a pulley connected to said friction wheel adapted to be driven by a belt led around two pulleys carried on said carriage and two pulleys on said frame whereby movement of said carriage does not vary the tension on said pulley; an axially movable shaft mounted on said frame and carrying one of said last named pulleys, said pulley being loosely mounted on said shaft; a. lateral pin on said pulley adapted to be engaged by a radial pin on said shaft to drive said pulley; a pair of spaced parallel discs fastened to said shaft and movable axially therewith; an electric motor mounted adjacent said shaft with its drive shaft extending between said discs and provided with a friction wheel thereon adapted to engage said discs; spring means for normally engaging one of said discs with said friction wheel; electromagnetic means for moving said shaft axially against the urging of said spring means to thereby disengage said first disc and engage said second disc with said friction driving wheel; a two-way control switch adapted when closed to close the circuit of said motor and adapted when open to be in series with said electromagnet; an auxiliary movable switch operated by a pulley engageable with said belt to be closedwhen said belt is moving forwardly, said auxiliary switch being in series with said control switch in open position to complete the electromagnetic circuit, and in parallel with said control switch in the motor circuit, whereby when said control switch is opened and said auxiliary switch is closed, said motor continues to operate but said electromagnet is energized to move said axially movable shaft to reverse the direction of said belt travel; means on said auxiliary switch and its pulley whereby reversal of said pulley will change the position of said auxiliary switch upon one complete revolution'of said pulley; and means operated by said electromagnet for disconnecting the sound head circuit upon energization of said electromagnet.

2. In phonographic apparatus having a support for a sound record and a movable carriage carrying a sound reproducing head engageable with said record, the combination of: a motor having a driving head coupled to its armature shaft; a pair of parallel spaced discs on opposite sides of said driving head coupled to a movable shaft; mechanism connecting said movable shaft to said carriage to drive the same; an electromagnet adapted to move said disc bearing shaft to disengage one of said discsfrom said driving head and to engage the other of said discs therewith to thereby reverse the rotation of said shaft and said carriage; a control switch for said motor; and an auxiliary switch which is closed by rotation of said apparatus in its forward direction and opened after a predetermined time upon reversal of said apparatus, said auxiliary switch acting then to open the circuit of both the motor and the electromagnet.

3. In phonographic apparatus having a support for a sound record and a movable carriage carrying a sound reproducing head engageable with said record, the combination of: a motor having a driving head coupled to its armature shaft; a pair of parallel spaced discs on opposite sides of said driving head coupled to a movable shaft; mechanism connecting said movable shaft to said carriage to drive the same; an electromagnet adapted to move said disc bearing shaft to disengage one of said discs from said driving head and to engage the other .of said discs therewith to thereby reverse the rotation of said shaft and said carriage; and said connecting mechanism including a driving pulley on said shaft, a stationary pulley, a pair of pulleys on said carriage, and a belt threaded around all of said pulleys and a driven wheel on said carriage, whereby movement of the carriage does not vary the tension on said belt.

RICHARD G. LEITNER. WILLIAM K. RIEBER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,308,556 Shank July '1, 1919 1,424,027 Murphy July 25, 1922 1,465,285 Peterson Aug, 21, 1923 1,783,115 Georg Nov. 25, 1930 2,076,298 Harris Apr. 6, 1937 2,219,930 Kellogg Oct. 29, 1940 2,287,809 Leonard June 30, 1942 2,302,732 Yetman Nov. 24, 1942 2,348,204 Brubaker May 9, 1944

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