US2624584A

US2624584A - Phonograph

Info

Publication number: US2624584A
Application number: US110793A
Authority: US
Inventors: Ronald J Rockwell
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-08-17
Filing date: 1949-08-17
Publication date: 1953-01-06
Anticipated expiration: 1970-01-06

Description

Jan. 6, 1953 R. J. RocKwELl. 2,624,584

PHONOGRAPH Filed Aug. 1'7, 1949 l IN V EN TOR. RONALD J. ROCKWELL HIS ATTORNEY Patented Jan. 6, 1953 UNITED STATES PATENT OFFICE PHONOGR'APH Ronald J. Rockwell, Cincinnati, Ohio Application August 17, 1949, Serial No. 110,793

Y Claims. l

This invention relates to phonographs of the type having mechanical sound reproduction systems and more particularly, to an improvement in the sound reproduction apparatus for such instruments.

At the present time there are several different types of small, inexpensive phonographs on the market which are designed primarily for use in the playing of childrens records, although they may, of course, also be used for playing other types of record-s if desired. These devices are generally of the type having a cabinet on which is mounted a turntable driven by a small electric motor. Also mounted on the cabinet is a tone arm to which is attached an acoustic reproducer or sound-box type of pick-up head in which the playing needle or stylus is mounted. The groove modulations picked up from thev record by the stylus are conveyed to a small diaphragm mounted in the sound-box. of the pick-up head.

The motion of this diaphragm causes air vibrations to be produced in a hollow tone arm which is communicatively connected with. a sound chamber provided in the cabinet of thev instrument. The cabinet. is provided', with an opening, generally along one side thereof, which communicates. with the sound chamber and from` whence the sounds reproduced` by the. instrument are rendered audible to the listeners.`

Phonographs of the aforementioned. type are phonograph in which the entire sound reproducl tion system is mounted upon and above the .outer end of the pick-up arm.

Another object of the invention is to provide a mechanically operated loud speaker apparatus for small phonographs in which the sound radiating cone is mounted directly above the record in order to provide a small and compact instrument.

Another object of the invention is to provide a sound reproducing apparatus for small, portable phonographs in which satisfactoryl reproduction may be obtained with a needle pressure of from one to two ounces.

Another object of the invention is to provide a sound reproduction apparatus for small, portable phonographs in which the frequency response is greatly superior to that of the conventional, sound-box types of reproducers.

Another object of the inventionY is to provide a sound reproduction apparatus for phonographs which consists of a pivoted pick-up arm, a pivoted needle holder mounted on the arm, a sound radiating cone, and a vertical drive rod connected between the needle holder and the cone.

Another object of the invention is to provide a resilient supporting element for stably supporting the drive rod of a mechanical type of sound reproduction mechanism for phonographs.

A further object is to provide a sound reproducing device of eXtreme simplicity which will produce eminently satisfactory performance and which can be manufactured with facility and at low cost. y

With these and other objects in view, as will more fully appear from the following description, I shall now describev my invention in conjunction with the accompanying drawings in which:

Figure 1 is a side elevation of a phonograph embodying my invention.

Figure 2 is a cross-sectional view taken along the line 2 2 in Figure 1.

Figure 3 is a. detail view of the pivoted element which receives and supports the phonograph needle.

Figure 4 is a fragmentary plan view of the pick-up arm.

In general, my improved sound reproduction apparatus comprises a small cabinet or base on which is mounted a turntable which is preferably driven by a small electric or spring motor located within the interior of the cabinet. Also supported on the cabinet is a pick-up arm which is mounted for pivotal movement in both a horizontal and a vertical plane so that the arm may be lifted from its position of rest and swung over the record mounted on the turntable after which it may be lowered so as to bring the needle or stylus into engagement with the sound track of the record. Similarly, after the record has .been played, the pick-up arm and stylus may be lifted off of the record and swung over to one side so as to permit the record to be removed and another one to be placed on the turntable.

The needle or stylus is received within a motion converting member which is pivotally mounted on the pick-up arm for oscillatory movement about an axis lying approximately parallel to the longitudinal axis of the pick-up arm.l Attached to this member is a vertically disposed drive rod which has` affixed to` its upper end a sound radiating cone which may be formed of stiff paper, fiber, metal or plastic material as may be desired. The rod is supported in its upright position by a resilient element through which the rod passes and which element is aiixed to a bracket formed on the pick-up arm or suitably attached thereto.

I have found that a sound reproduction apparatus of this type gives excellent results, the most noticeable improvement being in the extension and flattening of the frequency response and in the reduction of surface noise and high frequency chatter, which characterizes all of the sound-box types of reproducers with which I am familiar. Not only does my improved device result in a more natural and higher fidelity reproduction of the music or other intelligence impressed upon the record, but it also has the property of reducing the surface noise or needle scratch which is a contributing factor in the unpleasant reproduction obtained from other mechanical sound reproduction systems.

A further advantage of my device is that the pressure of the needle on the record may be made as small as one or two ounces, thereby greatly reducing the wear on the record and also reducing the surface noise caused by additive Wear of the needle on the record. I am able to achieve this result due to the light weight of the pickup arm and the mechanism mounted thereon so that better reproduction is obtained from the record and the life of the record is greatly increased. A further advantage of my device over the prior art devices resides in the fact that all of the sound reproducing mechanism is mounted on the tone arm above the cabinet and hence no provision need be made within the cabinet or base of the phonograph for transmitting the sound picked up off the record. Since relatively large acoustic volume need not be provided in the cabinet to serve in place of a horn type radiator, hence, the cabinet may be made smaller and more compact than in the case of phonographs of the latter type.

I will now proceed with the description of one illustrative embodiment of my invention, it being realized, of course, that various changes and alterations may be made in the specific features of construction of the device hereinafter described without departing from the principle or spirit of my invention.

In Figure 1 is shown a small phonograph in which the principles of the present invention are incorporated. As therein shown, the phonograph consists of a cabinet or base I on which is supported the driving motor and the phonograph turntable.

As shown in Figure 1 of the drawings a turntable I3 is arranged to be rotated in a well known manner by the motor, thereby causing a disctype record I4 mounted on the turntable to be rotated beneath the needle. The needle follows the modulations, representative of sounds, which have been impressed on the upper surface of the sound record disc.

Cooperating with the sound track, which in this case is assumed to be of the lateral-cut type, is a stylus I5 which is mounted near the outer end of a pick-arm I6. As shown in Figure 2, the pick-up arm is preferably formed in the shape of a channel so as to increase the rigidity and stiffness thereof and thereby enable relatively thin sheet stock to be used in fabricating the arm.

As shown in Figure 1, the right-hand or inner end of the pick-up arm I6 is pivotally mounted at I'I on a bracket I8 so as to permit the arm to be raised or lowered by grasping a finger tab or handle I9 provided on the left-hand or outer end thereof. The bracket I8 is in the shape of a U and the arm I6 is received between the side arms thereof and pivotally attached thereto as mentioned above. This pivotal attachment, as indicated at I'I in Figure l, is preferably achieved by forming inwardly extending extrusions or dimples in the bracket I 8 which are adapted to engage in apertures or recesses provided in the sides of the arm I5. The bracket I8 is preferably formed of resilient or springy material so that the extrusions on the arms thereof will spring into the recesses provided in the pick-up arm so as to hold the arm in position. The bracket I8 is in turn `iournaled on the cabinet I0 by means of a stud 2G, secured to the cabinet I0, which stud is provided on its upper end with a tenon of reduced diameter which passes through an aperture in the bottom of the bracket, the bracket being retained thereon by means of a headed screw ZI. It will be understood that any suitable arrangement for universally mounting the arm I6 may be substituted for the elements I1, I8, 20 and 2I.

In order to insure that any vibrations transmitted to the pick-up arm I6 by the stylus I5 will not be transmitted to the cabinet Il, which would act as a sounding board for the same and interfere with the proper reproduction of the record, the stud 20 is preferably insulated from the cabinet I0 by means of a block of rubber, felt or other resilient material so as e to prevent this from occurring.

As further shown in Figures 1, each of the upstanding arms of the bracket I8 is provided with an inwardly extending ear 22, the upper edge of which lies beneath the edge of the arm I6 and serves to support the arm in a substantially horizontal position when it is swung off to one side of the turntable I3. The rear face of each of the lugs serves to engage the lower edge of the arm I6 when the same is moved slightly beyond the vertical position, as indicated in phantom outline in Figure 1, and will maintain the arm in this position so as to facilitate the replacement of the needle I5 or the placing of a new record on the turntable.

As mentioned earlier herein, the entire sound reproduction system of the phonograph is supported on the arm I 6 and is entirely independent of the remainder of the phonograph assembly. The structure hereinafter to be described constitutes the sound reproduction apparatus of the device and, as the description proceeds, it will be observed that I have provided a very simple but effective apparatus for reproducing the intelligence impressed upon the record.

As shown in Figures 2 and 3, the stylus I5 is received within a bore provided within a member 25 which serves to convert the sidewise motion of the stylus into vertical motion. As shown in Figure 3 this bore is inclined at an angle of approximately 25 degrees to the vertical, when viewed from the side, so as to insure smooth tracking of the needle within the sound groove of the record.

The pick-up arm I6 is provided in the vicinity of the member 25 with a rectangular aperture in the upper face thereof, and one edge of the aperture is provided with a beveled knife edge 21, while the opposite edge thereof is provided with a notch arrangement 28 as shown in Figure 2. As shown in Figure 4, this aperture is incllned slightly-with respect to 'the axes of the arm I6 in order to reduce the tangential tracking error 'which occurs with short pick-up arms. The stylus receiving member '25 is provided with a pair of upwardly extending arms 3!! which are provided lnear their upper extremities with a pair of notches, one set of said notches-being adapted to cooperate with knife edge 21 and the other set being adaptedv to receive one edge of a spring clip 3|. The clip 3i is distorted from a-substantially iiat condition to an arcuate shape, as shown in Figure 2, and is compressed between the notches in the arms 30 and the notch arrangement 28 provided along one edge of the aperture formed in the upper face of the pickup arm I6. The member 25 is thereby held firmly in position on the pick-up .arm but is free to rock to a limited degree about the knife edge 21.

As shown in Figure 2, the stylus receiving member'l V25 is provided with a laterallyV extendingl arm 32 which is apertured to receive the lower end of a drive rod l33. This rod vmay* be brazed to lthe member.. 25 or otherwise `securely attached thereto so asfto insure the effective y transmission of the vertical motion of the stylus I5 to the rod. At its upper end, the rod 3.3 is threaded so as to receive nuts- 34 and conical washers 35 by means of which a sound radiating cone 3S is securely attached to,l and maintained 3 in position on, the upper end of the rod. The cone 36 may be formed of any relatively stiff but light material such as paper, relatively thin, pressed ber board, etc. However, if desired, the

cone may be molded of a thi-n pastic, or brous material, or it may be shaped from a light metal such as aluminum. Furthermore, while the cone is herein shown as being symmetrical in form, it may, if desired, be given an asymmetrical shape so as to more perfectly respond to the various I herein shown and described, I have employed a one-eighth inch metal rod which is approximately three and one-half inches in length with very satisfactory results.

While the embodiment of the invention herein shown and described is designed for use with lateral-cut records, it will be obvious to anyone skilled in the art that it may be readily adapted for use with vertical-cut records by moving the stylus from its present location to a position directly beneath the lower end of the drive rod 33. By so doing, the vertical movements of the stylus will be transmitted directly to the rod and thence to the cone which will convert the motion into sound.

As shown in Figures 2 and 3, the rod 33 passes upwardly from the member 25 through an aperture provided in the spring clip 3| and then through an enlarged aperture provided in the horizontally disposed flange 4D of an upwardly extending bracket Al formed on or otherwise attached to the arm I6. Secured to the iiange 46 is a block 42 of felt or other resilient material through the center of which is passed the rod 33. The block i2 is located approximately midway along the length of the rod and serves to support the rod'and maintain it in an upright position.

Inasmuch as the pick-up arm I6 itself is light in weight, and since the Weight of the member 25, the rod 33, and the cone 36 is in the neighborhood of but a few ounces, it is easily .possible to maintain a stylus pressure on the record oone or two ounces. However, if desired, counterbalancing of the arm I6 by means of a spring or weight may be employed in the well known. manner.

It is also desirable to design the member 25 so thatit will serve not onlyfas a motion connecting element but also as an impedance matching ydevice. For this purpose, the lever arm of the stylus (i. e., the distance from the point of the stylus to the knife edge 21) is so proportioned with respect to the lever arm of the rod (i. e., the distance from the lower end of the rod tothe knife edge 2) as to cause the sound radiating cone to be driven with the maximum power obtain-v. able from the sound track on the record. This principle of mechanically matching the impedance of the stylus with that of the cone is shown` though not described in U. S. Patent N o. 1,897,399, issued February 14, 1933 to R. J Rockwell et al. Accordingly, reference is hereby made to that patent for further information regarding this feature of the device.

Having thus described my invention, what l claim as new and useful, and desi-re tosecureby United States Letters Patent, is:

l. A sound reproducing device for phonographs comprising a cabinet, a pick-up arm having one end thereoi` pivotally attached to said cabinety-a stylus receiving member, means for supporting said member on said arm for pivotal movement about an axis lying approximately parallel to the major axis of said arm, a sound generating cone located with its periphery disposed in a plane parallel to the plane of the record, and a vertically disposed rod having one end attached to said stylus receiving member, and the other end attached to said cone for supporting Isaid cone in r position and for transmitting motion from said stylus receiving member to said cone, said supporting means including a knife edge form of pivot Aand a spring clip disposed edgewise to the stylus receiving member for holding said member lin place on the arm, said spring clip being aper- -tured to receive said rod.

2. In a phonograph of the type including a pick-up arm, a sound diaphragm mounted on said arm, a stylus, and means including a rocker member for communicating the vi-bratory motion of said stylus to said diaphragm, an improved device for pivotally mounting the rocker member in direct contact With the pick-up arm, comprising: a knife edge formation on the pick-up arm,`

a complementary notch formation on the rocker for receiving the knife edge, and resilient means for biasing said notch formation against said knife edge, said means including another notch formation on the rocker and a spring clip disposed edgewise to and in contact with said other notch formation.

3. In a phonograph of the type including Ia pick-up arm, a sound diaphragm flxedly mounted on said arm, a stylus and a diaphragm actuator, the improvement which comprises, in combination, a T-shaped rocker member -having a downwardly extending stylus receiving portion 4and an upwardly extending bifurcated portion and a laterally-extending actuator-engaging portion, and means for mounting said rocker member to rotate about 'an axis generally parallel to said arm in response to vibratory motion of said stylus, thereby to move said actuator in translation, comprising: a knife edge formedon said arm, individual V-notches on one side of the bifurcations of said arm in receptive relationship to said knife edge, a bow spring, a notch formed on said arm in receptive relationship to one end of said bow spring and other individual V-notches on the other sides of said bifurcations in receptive relationship to the other end of said bow spring.

4. The improvement in yaccordance with claim 3 wherein said bow spring is centrally apertured and wherein said diaphragm actuator projects through the aperture.

5. The improvement in accordance with claim 4 wherein said diaphragm actuator is stabilized by embracing damping material mounted in xed relation-ship to said pick-up arm.

Y 6.l A sound reproducing device for phonographs comprising a cabinet, a stylus, a pick-up arm having one end thereof pivotally attached to said cabinet, a T-shaped member for receiving the stylus and providing an impedance match to the cone, means for supporting said member on and in contact with said arm for pivotal movement about an axis lying approximately parallel to the major axis of said arm. said supporting means including a knife-edged form of pivot comprising notches on said stylus receiving member, and a spring clip apertured to receive said rod and disposed in engagement with one of said notches for holding the stylus receiving member in place on the arm, a sound generating cone located above said arm with its periphery disposed in a plane parallel to the plane of the record, and avertically disposed rod having one end attached to said stylus receiving member and the other end attached to said cone for supporting said cone in position and for transmitting motion from said stylus receiving member to said cone.

7. The invention as defined by claim 6 including an upwardly extending bracket attached to said arm adjacent to said rod, and a resilient supporting element attached to said bracket and in embrace with said rod.

RONALD J. ROCKWELL.

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

UNITED STATES PATENTS