US2391784A - Sound recording and reproducing machine - Google Patents

Description

Dec. 25, 1945. w. E. JOHNSTON 2,391,784

SOUND RECORDING AND REPRODUCING MACHINE Filed Nov. 4, 1943 Wil/fam E Johnon.

Patented Dec. 25, 1945 SOUND RECORDING AND REPRODUCING MACHINE- William E. Johnston, Weatogue, Conn., assigner to The Gray Manufacturing Company, Hartford, Conn., a corporation of Connecticut Application November 4, 1943, Serial No. 508,898

7 Claims.

rIhis invention relates to improvements in sound recording and reproducing machines of the type disclosed in the Proctor et al. Patent No. 2,296,870, and comprises la specific improvement on that machine.

The subject matter of this invention is concerned with novel mechanism for supporting the record disc, which in this type of machine is of thin exibile material, at the point of engagement with the stylus and the recording or reproducing head.

More specifically, the invention is concerned with a modication of the machine disclosed in the above Proctor patent comprising the shifting of the anvil of that patent from a point opposite the point of contact of the recording or reproducing stylus to a point transversely spaced with respect thereto so that the recording or reproducing stylus engages the record at a point between the points of support for the record comprising the shifted anvil and the driving wheels.

The exact nature of the subject matter of this invention will become apparent from the following detailed description thereof when taken in connection with the attached drawing.

This invention resides substantially in the combination, construction, arrangement and relative location of parts as will be described in detail below.

In the accompanying drawing the single figure is an illustration, somewhat diagrammatic in form, of a machine of the type disclosed in Proctor et al. Patent No. 2,296,870, and modified in accordance with this invention.

The subject matter of this invention is of particular use in sound recording and reproducing machines which employ a record blank of thin flexible material such as a disc of cellulose acetate a few thousandths of an inch thick. The Proctor et al. Patent No. 2,296,870 is representative of this machine and discloses in full detail one embodiment thereof which has reached the commercial stage. Only so much of the mechanism of that patent is reproduced in the drawing as is suiicient to fully understand the nature of the improvement thereon comprising the subject matter of this invention.

As illustrated in the drawing, the machine includes a frame I, a portion of which is illustrated, upon which is mounted in parallel relation a pair 0f rods 3 and G, Rod i is mounted on the extension 2 of the machine and the two rods are rigidly held in parallel spaced relation at their other ends by means of the tying member 5. A carriage B in the form of a box or housing is arranged to slide on the rods 3 `and 4 and is s upported thereby for sliding movement in what may be termed a radial direction with respect to the record blank. J ournaled on the housing is a vertical spindle I constructed es illustrated with a uted portion upon which record blank 9 may be keyed and centered for rotation therewith. The record blank consists of a thin disc of cellulose acetate or other suitable material upon which the sounds to be recorded are impressed, and from which they may be reproduced. Integral with the housing 1 is an extending arm 8 provided with a right angle extension between which and the housing extends a threaded shaft I0 rotatably mounted. The shaft I0 is connected to the spindle I by a set of gears. Pivotally mounted on a suitable xed support is a half nut I I which in one position engages the threads of the shaft I0.

Journaled on the frame I is a motor driven shaft I2, having secured to its end a friction driving wheel I3 positioned so as to engage the underside of the record blank 9. Freely and rotatably mounted on a shaft I5 is a cooperating friction wheel I4 positioned to engage the record blank at a point opposite the drive wheel I3. As shown in the above mentioned Proctor et al. patent, shaft l5 is mounted on a yoke which can be swung so as to move the wheel I4 into and out of engagement with the record blank,

Rctatably mounted on the frame I is the anvil wheel i0 which is positioned as shown in the drawing to engage the underside of the record blank 9 at a point radially displaced with respectl to the point of engagement of the drive wheel I3. The anvil wheel I6 may be provided, if desired, on its periphery with a cover of some resilient material such as rubber and the like for the purpose of noise reduction resulting from its driving cooperation with record blank 9. At I'I is diagrammatically illustrated a recording or reproducing head having a stylus I8. In the actual machine the head I'I is pivotally mounted but otherwise free so that it bears against the record tablet with a pressure determined by its weight. ln the actual machine there are two heads, that is a recording and reproducing head, both pivotally mounted on a mechanism so that when one is shifted into record engaging position the other is retracted from that position. Thus the stylus of either head will engage the record at a point between the anvil wheel I6 and the drive Wheel I3.

As previously mentioned the complete details of construction of such a machine are illustrated in the Proctor et al. patent. The disclosure herein differs in that the anvil I6 instead of being opposite the stylus has been shifted to one side and away from the friction wheel I3.

The advantages of shifting the anvil to one side of the recording or reproducing point as distinguished from the structure of the said patent are threefold. The first and most important advantage is that the tendency of the thin record disc to fracture with changes in stylus radius, lubrication, etc., is minimized. The ability of the record material to properly record under wide temperature and humidity changes is increased. Finally, a more constant groove depth is secured notwithstanding all of these variables, and particularly changes in temperature. There may also be mentioned the subsidiary advantage that the slight distortion caused by modification of the recording and reproducing styli action when opposed by the anvil is eliminated. In the operation of the machine wheel I4 is moved to raised position when the machine is at rest and both the recording and reproducing heads are retracted so that their styli are not in record engaging position. Under these conditions a record blank 9 may be slipped between the Wheels I3 and I4 and impaled on the spindle 1. Half nut I I is raised out of engagement with the shaft Il) and the carriage 6 moved to the extreme right during recording. The recording head I1 is moved to record engaging position so that its stylus will contact the record blank at a point near its center. To put the machine in operation wheel I3 is set in motion and wheel I4 is brought down to engage the record blank. As a result it is gripped between the friction wheels I3 and I4 and is caused to revolve at a constant angular` velocity. The rotation of the plunger causes rotation of spindle 1, and hence rotation of shaft I0 through the gear connection in the carriage 6. With the half nut I I in engagement with shaft I0 but fixed against movement, the rotation of shaft I0 will cause the carriage 6 to move slowly to the left, sliding on the rods 3 and 4. Of course, the record blank 9 moves with it, with the result that the record stylus traces a spiral path of greatly increasing radius outwardly from a point near the center of the record to a terminal point near its periphery. In the actual machine the travel of the carriage is quite slow so that the spacing between adjacent record grooves is about one five-thousandths of an inch. As illustrated, any impressions which the recording stylus make on the record are not restrained or modified because the stylus engages the record blank at a point between the rotatable anvil I6 and the drive c.

wheel I3 which provide spaced support points for the record material lying on opposite sides in a radial direction of the stylus I8.

In addition to the removal of the restraint of the stylus during recording and reproduction by shifting the anvil the very important advantage of minimizing the tendency of the record material to fracture is obtained. As previously noted during recording and reproduction the styli travel outwardly from a point near the center of the record disc towards its periphery, resulting in changes in what may be termed the stylus radius which imposes fracturing strains in the material. These strains vary with conditions of lubrication, temperature and humidity. However, by reason of the construction shown the tendency to fracture is minimized under all conditions. Furthermore, the ability of the record material to make a proper record is improved under wide temperature and humidity changes. Furthermore, notwithstanding all of these prior factors, a more nearly constant groove depth is secured by' reason of the structural change disclosed.

A similar operation of the machine, with the advantages mentioned above, results during reproduction, the only difference is that the reproducing head which is equally well represented by the diagrammatic element I1, is moved to a position so that its stylus engages the spiral record groove formed in the blank.

While the specific embodiment disclosed herein is in connection with the machine employing a rotatable anvil, it is to be understood that the subject matter of this invention is equally applicable to a machine employing a fixed anvil. In other words, in place of the rotatable anvil I 6, a suitable shaped immovable anvil could be used. of course in the same position as the anvil I 6, that is laterally displaced with respect to the stylus. I do not, therefore contemplate the limitation of this invention to a machine employing a rotatable anvil.

From the above description it Will be apparent to those skilled in the art that the subject matter of this invention is capable of some variation, and I do not therefore, desire to be strictly limited to the disclosure herein given, but rather by the scope of the appended claims.

What is claimed is:

1. In a sound machine of the type described,

' the combination including a record supporting carriage, a driving wheel positioned to engage a record blank when mounted on said carriage, an anvil positioned to engage the same side of the record blank, and a recording head having a stylus -positioned to engage the record blank at a point between the driving wheel and the anvil.

2. In the combination of claim 1, said recording head being supported solely by the record blank during recording.

3. In the combination of claim 1, said recording head being supported by the record blank during recording, and its stylus engaging the record blank on a radial line including the points of contact between the record blank and said wheel and anvil.

4. In the combination of claim l, said anvil comprising a rotatable member.

5. In a sound machine as described, the combination including means forming a guideway, a record carrying carriage mounted on said guide.. way, driving wheels positioned to engage a record blank on opposite sides when mounted on said carriage, an anvil mounted to engage the record blank on one side, and a recording head positioned to engage the record blank on the side opposite said anvil at a point between it and said friction wheels, said record blank being unsupported at this point except by the anvil and adjacent friction wheels.

6. In the combination of claim 5, means opera-ted by the rotation of the record blank for causing movement of the carriage on its support.

1. In the combination of claim 5, said anvil being a rotatably supported wheel.

WILLIAM EDWARD JOHNSTON.

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