US2392111A - Automatic record changer for phonographs - Google Patents

Description

Jan. 1, 1946. H. v. AL EXANDERSSON 2,

AUTOMATIC RECORD CHANGER FOR PHONOGRAPHS Filed Jan. i943 INV NTOR Patented Jan. 1, 1946 AUTOMATIC RECORD CHANGER Fort PHONOGRAPHS Harald Valdemar den, minor to Alexandersson, Lidingo, Swe- Ag'a-Baltlc Aktiebolag, Stockholm, Sweden, a corporation Sweden Application January 8, 1943, Serial No. 471,711 In Sweden September 5, 1942 2 Claims.

My invention relates to automatic record changers for phonographs.

, Phonograph records as a rule are provided with a so-called final groove, that is, a groove which does not carry a sound record, but which is joined to the end of the innermost sound groove, and has a substantially greater pitch than the sound groove. The purpose of the final groove is to carry the pick-up arm inwardly towards the centre of the record with a greater angular speed than that at which the pick-up arm is moved during the reproduction. This greater speed causes the record changing to begin, For this purpose there has been employed a meansin frictional engagement with some member partaking of the turning movement of the pick-up arm, so that the first mentioned means normally turns together with the pick-up arm. Preferably once during each revolution of the turntable this means is influenced in such a way, thatit is turned back into a fixed initial position against the action of the friction. This turning movement is momentary, but it is through a very small angle, corresponding to the angle through which the pick-up arm has been moved during one revolution of the phonograph record. When the needle of the pick-up arm enters the final groove, the turning angle, however, is much greater due to the greater pitch of the final groove, and arrangements then are made by means of which this greater turning angle actuates the means by which the record changing is started.

In arrangements of this kind every turning of the pick-up arm with a speed which is greater than the normal speed when reproducing a rec- 0rd, causes the record changing operation to be started. This, however, is objectionable. As is well known, phonograph records are normally of two standard dimensions, known as 12 inch recduh; and 10 inch records, respectively, but there are also certain records having still smaller dimensions. When it is desired to reproduce such a small record in a phonograph having an automatic record changer of the above type, it is necessary to carry the pick-up arm inwards to the initial groove of such record by hand, but this movement b hand as a rule cannotbe made sufficiently slowly, but due to its rapid speed it causes a record changing operation to be initiated, so that the pick-up arm is carried outwards into an outer position and thereafter again inwards into a position corresponding to the initial groove of a 12 inch or a 10 inch record, respectively, thus making it impossible to reproduce records having a diameter less than 10 inches.

stop means Further it may happen some reason or another to hear only the last part of a normal record. With the hitherto known phonographs provided with automatic record changers, it was, however, not possible to carry the pick-up arm into a position adjacent to the middle of the record, because relatively rapid inward movement of the pick-up arm necessary therefor, initiated a changing operation.

The present invention is based upon the fact, that the pick-up arm is always elevated into a position above the record to be recorded, when such rapid movements are made which should not cause a record changing tion there is arranged a stop means for the means which cause a record changing operation, said 3 being influenced by the pick-up arm in such a way that, in the elevated position oithe pick-up arm, it prevents the other means from coming into action.

The invention will be described below in connection with the annexed drawing. in which Fig. 1 shows a part of the starting arrangement in horizontal projection and is taken on the line l-l of page 2, and Fig. 2 shows the corresponding part in vertical projection.

In the form of the invention shown in the drawing, it is assumed that the record. changer arrangement is of the kind which is controlled by a disc, so as not to be moved during the playing of a record,.but immediately thereafter is moved in order to initiate the record changing. The disc is driven by means of a friction wheel which engages the periphery of the disc or the periphery of another wheel connected to the disc. In order that this shall not continuously drive the-disc a recess is provided in the periphery in question, in which the friction roller moves freely during the playing. In order that the movement of the disc shall be started, given an impulse for movement in the correct direction, so that the friction roller rides out of the recess and up on the periphery of the disc.

In Fig. 1, It indicates the shaft of the turntable. It is assumed that the device isseen from above with the turntable removed, the turntable being indicated at H, and the driving roller [2 of the disc as well as the disc l3 therefor being visible in the figure. The above mentioned recess in the periphery of the disc is indicated I4, and as the device as shown in Fig. 1, is assumed to be in its normal playing position, the cam disc is stationary, the driving roller l2 rotating freely in the recess M.

The shaft about which the pick-up arm turns that one wishes for it is only necessary, that it be is' indicated at l5. It will be evident from Fig. 2 how this cooperates with the above mentioned means as well as with the pick-up arm I 8. The pick-up arm is carried in the usual manner by a bearing arrangement l1, through which the shaft extends, and which contains the required means for raising and lowering the pick-up arm in connection with the record changing. -.A thin blade spring I8 is frictionally engaged between two eollars l9 and 20 on the shaft l5. This blade spring preferably extends to the vicinity of the shaft id of the turntable I I and the driving roller l2 of the disc l3, where a flang 2| is fixed at right angles to the spring It.

On the shaft to below the turntable there is mounted a bushing 22, provided with an upwardly extending pirr 23. Further, the disc is provided with an axially extending cam surface 24 extending downwardly from the perimeter of the disc and having a vertical edge 25 and an inclined edge 26.

The arrangement functions in the following manner: During the playing of a record the pick-up arm is slowly and continuously turned toward the centre of the record due to the cooperation with the spiral groove in the record and the needle carried by the arm. The shaft l5 and the collars i9 and 20 mounted thereon are thus slowly rotated. The spring l8, which is mounted with friction between these collars, therefore will be turned a corresponding distance for each revolution of the rec- 0rd. However, as thespring I! approaches the shaft I 0, the pin 23 strikes the flange 2| on the spring every time the shaft I0 makes a revolution to thereby move the spring back so that the pin just clears the flange. During the following revolution the spring will again be turned by the pick-up arm a distance corresponding to the pitch of the sound groove, and the pin 23 will again strike the flange 2| and move the spring back. During this movement to and fro the spring will ride on the outermost part of the cam surface 24.

When the record is fully played, the needle enters a portion of the spiral groove having a greatly increased pitch with the result that the arm l6 and hence the spring is is turned a greater distance than during the playing of the record. This movement is sufllciently great so that the spring rides over the outermost part of the cam 24 and springs upwardly in front of the vertical edge 25. When struck by the pin 23 upon the next revolution of shaft lo the spring I 8 is turned back as usual, but the spring carries the disc 13 with it in its movement due to the cooperation between the spring l8 and the vertithe roller l2 to ride up on the periphery of the disc I3, whereby this disc is rotated one revolution, until the roller l2 again enters the recess l4. During this movement the disc causes all of the operations connected with the record changing to take place, such as the elevation of the pick-up arm from the record, the swinging out of the arm into a position entirely beyond the record, the moving into place of the new record, the turning inwards of the arm into a position immediatel over the initial. groove of the new record and the lowering of the arm into this groove. However, inasmuch as the structure for performing these operations forms no part of the present invention, it has not been shown or described.

During the movement of the pick-up arm the cal edge 24. This turning of the disc 13 causes spring I! has followed the pick-up arm in its movement, as far as permitted by the means for limiting the movement of the spring. In the arrangement shown in the drawing it was assumed that the movement of the spring was limited so that it could not move past a stop pin 21 in one direction and that its movement in the other direction was limited by means of the pin 23 so as always to be kept at a suitable distance from the shaft lo. It should be observed that during this part of the working period, the spring does not cooperate with the surface 24 as the disc l3 was moved immediately after starting so that this edge was moved away from the spring. When the record changing is almost fulfilled, suitably during the period when the pick-up arm is lowered into the initial groove of the new record after it has already been swung in above this groove, the surface 24 will again fully or partially extend below the spring is, whereby the spring is again elevated into its normal working position, and the playing of the new record may begin.

Now it is obvious, that if the pick-up arm I should be turned by hand at a, greater speed than that at which it normally moves during the reproduction, the spring I8 will strike the edge 28, and during the next revolution of the shaft I O the disc l3 will be started. so that a record changing is initiated. This is what is to be prevented according to the invention.

According to the invention a spring 29 is rivcarrying the record changer arrangement. The spring 29 is provided with an arm 3|, which extends under the shaft II of the pick-up arm I O. In this connection it should be kept in mind that the elevation and lowering movements of the pick-up arm I 6 normally take place so that, by means of arrangements which are not shown in the drawing, the shaft I5 is moved vertically. As the shaft I5 contacts the pick-up arm ii at a point, spaced from the pivot 32 of the pick-up arm IS, the pick-up arm will consequentl be swung upwards or downwards. Usually the shaft, which is movable in vertical direction in order to cause the pick-up arm to be pivoted up or down is arranged as an inner shaft, passing within the shaft i5. How this shaft is arranged, is, however, without importance to the invention. The main point is that the shaft cooperates with the spring 29 in such a manner that this spring is deflected to a lower position and is restored to the higher position when the pick-up arm 16 is elevated.

Adjacent to the outer free end of the spring 29 there is arranged a pin 33 so located as not to be in the path of movement of the spring it when the pick-up arm I6 is in its reproduction position, but is elevated by the spring 29 so as to be in the path of movement of the spring I 8 when the pick-up arm lGis elevated. The pin 33, in a manner which is evident from Fig. 1, will contact the edge of the spring l8, so that the pin prevents that movement of the spring II which would cause the spring to ride over the cam 24 and engage the edge 25. Consequently, the disc I3 is not rotated and hence is not engaged by the roller l2.

The invention is, of course, not limited to the form shown in detail and described, but substantial modiflcations'may be made within its scope. Thus, for instance, the spring I 8 may be turned by means other than the shaft ii, if such means the vertical edge 25 on' when the pick-up arm I6 is lowered into its reproduction position,

transferring relation with said 23 may also be arranged in conshaft than the centre shaft is in movement shaft. The pin nection with another of the turntable.

I claim:

1. In a phonograph, a turntable, means for rotating said turntable, a pickup arm for cooperating with a record on said turntable, said record having a playing groove and a tripping groove, means formounting said arm so that it may pivot in both a horizontal plane and in a vertical plane, a vertical shaft connected to said arm so as to be turned when said arm is pivoted in a horizontal plane, a rotatably mounted record-change initiating disc, a cam abrupt face, a cam actuating arm frictionally engaged by said shaft so as to be turned a predetermined distance towards engagement with said cam face by turning of said pickup arm and shaft during each revolution of said turntable when the pickup arm is cooperating with the playing groove on said disc having an of said record, a member movable in timed rela- I tion'to the rotation of said turntable, the path of movement of said member intersecting the path of movement of said actuating arm as the latter approaches said cam face whereby the actuating arm is moved back once during each revolution of said turntable, said predetermined distance of movement of said actuating arm being insuflicient to bring it into engagement with said cam face before it is moved back by said memgaged by said shaft as mined distance towards engagement with said.

2. In a phonograph, a turntable, means for rotating said turntable, a pickup arm for cooperating with a record on said turntable, said record having a playing groove and a tripping groove, means for mounting said arm so that it may pivot in both a horizontal plane and in a vertical plane, a vertical shaft connected to said arm so as to be turned when said arm is pivoted in a horizontal plane, a rotatablymounted record-change initiating disc, a cam on said disc having an abrupt face, a cam actuating arm frictionally ento be turned a predeter cam face by turning of said pickup arm and shaft during each revolution of said turntable when the pickup arm iscooperating with the -play-' ing groove of said record, a member movable in timed relation to the rotation of said turntable, the path of movement of said member intersecting the path of movement of said actuating arm as the latter approaches saidcam face whereby the actuating arm is moved back once during each revolution of said turntable, said predetermined distance of movement of said actuating arm being insufficient to bring it into engagement with said cam face before it is moved back by said member, said actuating arm being moved a greater distance when said pickup arm cooperates with the tripping groove of said record so as to engage said cam face before the actuating arm is moved back by said member, whereby subsequent movement of said actuating arm by said member actuates said cam, a spring member normally disposed out of the path of movement of said actuating arm, and an element moved by an upward pivoting of said pickup arm in a vertical plane to position said spring member in the path of travel of said actuating arm towards engagement of said cam face by the actuating arm.

HARALD VALDEMAR ALEXANDERSSON.

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