US2255218A

US2255218A - Phonographic apparatus

Info

Publication number: US2255218A
Application number: US306833A
Authority: US
Inventors: John J Hoehn
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1939-11-30
Filing date: 1939-11-30
Publication date: 1941-09-09
Anticipated expiration: 1958-09-09

Description

Sept. 9, 1941. J. J. HOEHN PHONOGRAPHIC APPARATUS Filed Nqv.. 50, 19:59 2 Sheets-sheaf, 2

Zmnentor Patented Sept. 9, 1941 rnoNoGn'Armc APPARATUS John J. Hoehn, Indianapolis,-Ind., assignor to Radio Corporation of America, a corporation of Delaware Application November so, 1939, Serial No. 306,833 7 Claims. (01. 274-9 This invention relates to phonographic apparatus, and more particularlyto recording apparatus used inrecording upon blank discs or cylinders which may be played back immediately after recording, the present invention being in the nature of an improvement upon that disclosed in the copending application of Harold J.

Hasbrouck, Jr., Serial No. 256,270, filed February 14, 1939, and assigned to Radio Corporation of America.

In the said copending application, there is disclosed a recording machine wherein the recording head is carried on a pivotally mounted cradle and is fed across the record by a feed screw which may be driven from the turntable spindle, for example, damping means being provided in conjunction with the aforesaid cradle to prevent substantial vibration or oscillation of the cutter head in a direction normal to the surface of the record with which the cutting stylus is in contact. -An adjustable spring'is provided for regulating the depth of cut of the cutting stylus.

While a construction of this sort afiords very good results, the load of the cutter head on the supporting bearing therefor is relatively great and the cutter head does not oscillate as freely on. its bearings as is sometimes desirable, par- In accordance with my present invention, 1.

suspend the floating cutter head mounting bracket or cradle by means of two separated tension springs. The tension of one spring is preferably made adjustable-by means of a suitable screw and thumb nut to control the depth of the cut groove, while the assisting spring is preferably of fixed tension, although it may also be made adjustable as to tension if desired. In any case,.the tension of the assisting spring is weaker than that of the'spring which controls the cutting depth. It follows, therefore, that the two springs cannot have the sameperiods, and therefore the control of the vertical oscillation of the cutter and its carriage passes automatically from one spring to the other. At

the same time, theme of two springs, one on .each side of the cutter head, balances the load on the cuter head mounting bearings.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, as well as additional objects and advantages thereof, will best be understood from thefollowing description of one embodiment thereof, when read in connection with the 1 accompanying drawings in which ticularly since there is an unequal load on the two pivot bearings, so that best results can not always be obtained with a construction of this sort. Y

The primary object of my present invention is to provide an improved cutter head suspension for recording machines wherein the aforementioned difllculty is obviated.

More particularly. it is an object of my present invention to provide, in phonographic apparatus as aforesaid, an improved cutter head suspension wherein the load on the cutter head mounting bearings will be balanced, or substantially equalized, thereby providing freedom for oscillatory movement of the cutter head.

Another object of my invention is to provide an improved cutter head suspension by means of which more delicate adjustment of the depth of the needle cut will be possible.

A further object of my present invention is to provide an improved cutter head suspension, as above described, which can be readily adapted to existing recording machines.

It is also an object of my present invention to provide an improved cutter head suspension, as aforesaid, which is very simple in construction and highly efilcient in use.

- carrying a pair of guide rods 5 and a rotatable Figure 1 is a front elevation of a portion of a recording machine showing my improved cutter head suspension applied thereto,

Figure 2 is an end elevation as seen from the left in Fig. 1,

Figure'3 is a sectional view taken on the line III-111; of Fig. 1, and

Figure 4 is a sectional view taken on the. line IVi-IV of Fig. 1.

Referring. more particularly to the drawings, wherein similar reference characters designate corresponding parts throughout, there is shown a motor board i upon which is pivotally mounted for universal movement thereon a frame 3 feed screw 1 on which a carriage 9 is slidably and rotatably mounted, the carriage 9 being provided with a pair of downwardly and forwardly extending arms H. The carriage 9 also pivotally carries a latch lever. II which is formed with a half nut l6 adapted to cooperate with the feed screw 1 whereby the carriage 8 and the parts'carried thereby may be fed radially across a record blank R supported an a suitable turntable ii. The latch lever I3 is also provided with a latching toe i8 which is adapted to engage the upper guide rod 5 when the carriage Sand the latch lever l3 are rotated on the feed screw 1 a suiilcient distance in a counter-clockwise direction, as viewed in Fig. 2.

Arranged to cooperate with the record blank R is the cutting stylus 2.1 of a cutter head 23 to which is fixed a rearwardly extending cradle 25 pivotally mounted on a pair of spaced pivot bearings 21. The pivot bearings 21 extend in opposite directions, as clearly shown in Fig. 1, and are carried by a pair of parallel links 29 which, in turn, are pivotally mounted on a pair of spaced, cooperating pivot bearings 3| carried by the arms ll of the carriage 9, the ,carriage 9 thus constituting a supporting member for the cutter head 23, its cradle 25, the bearings 21-, the links 29 and the-bearings 3|. A damping member 32 of any suitable construction is preferably provided for the cutter head 23 by securing it to the cradle 25, for example.

Slidably mounted within the carriage-9 for vertical movement thereon is a suitable block 24 which may be adjusted in a vertical direction by means of a thumb screw 33, a link 35 connecting the aforesaid block with the links 29 to permit adjustment of the assembly in a direction normal to the surface of the record R. In addition, there is pivotally mounted on the aforesaid block an operating handle 31 which pivotally carries a connecting link 39. The linkv 39 has a slot 4| formed on its lower end to receive a pin 43 on the cradle 25. To raise the cutting stylus 2| from record blank R, it is merely necessary to raise the handle 31 whereupon the play in the slot 4| is first taken up, after which the end of the slot engages the pin 43 to raise the cradle 25 and the cutter headl23. Lowering of the handle 31 will, of course, bring the cutter head 23 back into engagement with the record blank R.

To balance the load of the cutter head 23 on ,the

pivot bearings

21 and 3|, I have provided a pair of tension springs 45 and 41. The spring 45 has one end fixed to a pin 49 on the cradle 25 and its other end secured toa screw which is adjustable by means of a thumb nut 53 on an extension 55 of a bracket 55 fixed to the block 24. Adjustment of the thumb nut 53 varies the tension in the spring 45 and thereby more or less counterbalances the cutter head 23 to regulate the depth of .cut of the cutting stylus 2|.

' weaker than is customary and therefore a finer adjustment of the cutting depth of stylus 2| is possible. Moreover, by making the tension of the fixed spring 41 weaker than the tension of the spring 45, it is obvious that the two springs will not .have the same periods, and the control or the vertical oscillations oi the cutter carriage will spring 41.

automatically pass from the spring 45 to the Although I have shown and described but one embodiment'of my invention, I am fully aware that other modifications are possible, and I therefore desire that my invention shall not be limited except insofar as is made necessary by the prior art and by the spirit of the appended claims.

1. In phonographic apparatus, the combination of a supporting member, a pivotal mounting thereon including spaced bearing parts, a sound translating device pivotally carried by said mounting, and means comprising a plurality of resilient members substantially equalizing the load of said pick-up on said bearing parts,

2. In phonographic apparatus, the combination of a supporting member, a pivotal -mounting thereon including spaced bearing parts, a sound translating device pivotally carried by said mounting, and a pair of springs substantially equalizing the load of said pick-up 'on said bearing parts.

The spring 41 is preferably of a fixed, predeter- 3. In phonog raphic apparatus, the combination of a supporting member, a pivotal mounting thereon including spaced bearing parts, a sound translating device pivotally carried by said mounting, and a pair of tension springs substantially equalizing the load of said pick-up on said bearing parts, said springs each having a different tension.

- 4. In phonographic apparatus, the combination of a supporting member, a pivotal mounting thereon including spaced bearing parts, a sound translating device pivotally carried by said mounting, a pair of tension springs substantially equalizing the load of'said device on said bearing parts; and means for adjusting the tension of at least one of said springs.

5. In phonographic apparatus, the combination of a supporting member, a pivotal mounting thereon including spaced bearing parts, a sound translating device pivotally carried by said mounting, a pair of tension springs substantially equalizing the load of said device on said tion to each other, a cradle pivotally carried by said bearings, a sound translating device carried by said cradle, and a pair of tension springs connecting said cradle to said supporting member, one of said springs being located adjacent one of said bearings and the other of said springs being located adjacent another of said bearings,

the tensions of said springs being or such a magnitude as to substantially equalize the load on each of said bearings.

JOHN J. HOEHN.