US1390206A - Vibration-transmission connection for talking-machines - Google Patents

Description

M. 0. HOPKINS. VIBRATION TRANSMISSION CONNECTION .FOR TALKING MACHINES.

APPLICATION FILED JUNE 7, I920.

Patented Sept. (8, 1921..

III A M fifmaw MARCUS C. HOPKINS, OF CHEVY CHASE, DISTRICT OF COLUMBIA.

VERATION-TRANSMISSION CONNECTION FOR TALKING-MACHIN ES.

Specification of Letters Patent.

Patented Sept, 6, 1921.

Application filed June 7, 1920. Serial No. 387,029.

T allcolwm it may concern:

Be it known that I, MARCUS C. HOPKINS, a citizen of the United States of America, and residing at 3777 Oliver street, Chevy Chase, District of Columbia, have invented certain new and useful Improvements in Vibration-Transmission Connections for Talking-Machines, of which the following is a specification.

This invention relates to vibration-transmission connections for talking machines, such as are interposed between the stylus holder and the diaphragm to transmit to the latter the vibrations set up by the passage of the stylus along the phonic line or sound groove'of a record during playing.

The invention has special reference to talking machines of the type disclosed inmy prior Patent No. 1,271,527, granted July 2, 1918, in which the usual sound-box and tone arm are replaced by a swinging arm which moves horizontally across the record and carries at its rear end a large conical or equivalent diaphragm of vibratile material, the front end of the arm having a stylus holder attached directly to it. The swinging arm is made hollow or tubular, and through it extends a transmission element which is connected at one end to the stylus holder and at the other end to the apex of the diaphragm, so that the vibrations to which the transmission element is subjected are exerted upon the diaphragm which is thereby caused to vibrate piston-fashion and, in consequence, acts to regenerate the original soundwaves in their initial tonal strength and quality in free, unconfined atmospheric air.

According to the earlier construction; the transmission element had the form of a wire or equivalent member which was originally placed under tension by suitable devices, but was subsequently utilized in an untensioned condition. It was also proposed to replace the wire rod by a two-part element comprising metallic and non-metallic sectlons, prefcrably brass or steel and ebony, the purpose being to deaden by means of the wooden section'the special vibrations developed as a characteristic of the metal.

I have now found, however, that I can obtain a reproduction possessing a much greater degree of brilliancy and sharpness, and with much less blasting and chattering, by employing, instead of the forms previously used, a transmission element which consists of a metal rod, preferably brass,

having a relatively-large diameter as compared with the former devices and extremely thin walls The ends of this rod are reduced or narrowed, and are attached, one to the apex of the diaphragm and the other to the base portion of the stylus holder, which latter is preferably mounted upon knife bearings provided on the cap at the front end of the swinging arm, instead of being attached to a leaf spring connected to the arm end as was formerly proposed.

An embodiment of the invention is illustrated in the accompanying drawing; but it is to be understood that no limitation to the precise structural details of such disclosure is contemplated, as the invention is susceptible of modifications and changes within its scope as hereinafter claimed.

In the drawing:

Figure 1 is a part-sectional side elevation of a diaphragm and carrier arm and associated parts of the general type disclosed in my above-identified patent.

Fig. 2 is an enlarged cross-section on line 2-2, Fig. 1.

eferring more particularly to the drawing, 5 indicates generally a conical diaphragm constructed of paper or other suitable stiff and vibratile sheet material and mounted by means of a spider 6 on the rear end of a hollow arm or tube 7 which is arranged to move horizontally across the record and which is provided at its front end with a stylus holder 8. The conical diaphragm has, by preference, the dimensions specified in my previously identified patent, and to its apex there is connected one end of the vibration-transmission element 9, the other end of which is connected to the stylus holder. The latter is here shown as of the type usually employed in the standard Path machines, and comprises a chuck 10 adapted to receive the usual sapphirepointed stylus 11 for' playing vertical-cut records; but it will be understood that such stylus can beremoved and replaced by a steel, or other stylus when a lateral-cut rec'- ord is to be played, in which case the arm 7 is turned through an angle of 90 and the stylus holder itself thereafter adjusted. The feature of setting or adjusting the arm and stylus holder for universal playing purposes forms no part of'the present in.- vention, however, and consequently requires no special description nor illustration; it is fully disclosed in Letters Patent No. 1,218,083, granted October 7, 1919, to Fredrick E. Jose, to which reference may be had for a complete understanding thereof. The base or cross-piece 12 of the holder is fulcrumed on knife-edge pivots or bearings 13 carried by the cap 14 onthe front end of the arm, and is subjected to the pressure of tension springs 15 controlled by screws 16.

The carrier arm or tube 7 is provided a Slight distance in front of the hub of spider 6 with a pair of spaced rings 17, which are rigidly secured to it and between which there is interposed a wider ring or sleeve 18 in which the arm rotatably fits to enable the above-mentioned adjustment of said arm from either of its two playing positions to to the other. This sleeve 18 is pivotally supported by means of a pair of pins 19 (only one of which appears) in the upper portions of the arms of a vertically-disposed yoke 20,- the stem of which fits rotatably in a sleeve bearing (not shown.) forming part of a supporting bracket adapted to be fastened to the cabinet of the machine at some suitable point. The above described mounting therefore constitutes, in effect, a universal oint which provides for swinging movement'of the arm in both horizontal and vertical planes, as will be understood.

The transmission element, which constitutes the most important feature of my invention, consists ofa hollow metal rod or tube, preferably constructed of brass and having very thin Walls. It is arranged eccentrically of the arm bore and has a diameter which is quite large as compared withthe diameters of the transmission'elements previously proposed in connection with machines of this character, as well as those used in the ordinary sound-boxes. In practice, it may vary frOmone-quarter to three-eighths of an inch in diameter, whereas the rods or wires or vibrator bars previously used had a diameter less than oneeighth of an inch; while the'arm itself has a diameter of approximately one inch. As

shown, the diameter of the rod is constant, excepting at the ends of the rod where it is considerably reduced to permit its connection to the apex of the diaphragm and the base or cross-piece 12 of the stylus holder. At its point of attachment to the said crosspiece, it is, in fact, narrowed and flattened out to form a virtual knife-edge 21, which is received in a notch or kerf 22 in the crosspiece.

The reduced portion at the rear end of the transmission rod is preferably formed by a plug 23 which is threaded into the rod end and is contracted centrally as at 24, as shown; such construction affording the requisite vibratory movements of the rod which would otherwise be too rigid to vibrate properly.

I claim as my invention:

1. A talking machine element for transmitting vibrations from a stylus holder to a diaphragm, comprising a metal tube having extremely thin walls.

2. A talking machine element for transmitting vibrations from a stylus holder to a diaphragm, comprising a thin-walled, tubular metal rod having its major portion of constant diameter.

3. A talking machine element for transmitting vibrations from a stylus holder to a diaphragm, comprising a straight tubular metal rod having its major portion of constant diameter and at least one-end of reduced diameter.

4. A talking machine element for transmitting vibrations from a stylus holder to a diaphragm, comprising a thin-walled, tubular metal rod having its major portion of constant diameter and at least one end of reduced diameter.

5. A vibration-transmission element for talking machines, comprising a thin-Walled, tubular metal rod of relatively large diameter.

In testimony whereof I have aflixed my signature.

MARCUS O. HOPKINS.

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