US1428819A - Manufacture of sound records - Google Patents

Description

A. F. SYKES.

MANUFACTURE OF SOUND RECORDS.

APPLICATION FILED NOV. 30. 1,920.

1,428,8190 PatentedSept. 12,1922

lf atented Sept. 12, 11922.-

" STAT ADRIAN FRANCIS SYKES, OF NEW BARNET, ENGLAND.

MANUFACTURE OF SOUND RECORDS.

Application filed November 30, 1920. Serial No. 427,373.

To all whom it may concern:

Be it known that I, ADRIAN FRANoIs SYKES, a subject of the King of Great Britain, residing at Arundel House, Warwick Road, New Barnet, Hertfordshire, England, have invented a new and useful Imrovement in the Manufacture of Sound ecords, of which the following is a specification.

This invention relates to the manufacture of sound records on the hill and dale system. The sounds recorded on such records are usually reproduced by means of a small sphere of sapphire or diamond which is kept pressed down into the sound track. When such a sphere rides over the impressions in the sound track its motion is not in conformity" with the impressions because owing to the varying inclination of the surface presented to the sphere the point of the sphere which is in contact with the record rapidly changes and the sounds are therefore distorted. In order that my invention may be the more readily understood T will at once refer to the accompanying drawing, Figure 1 of which is a diagram illustrating the nature of the falsification or distortion introduced by the size and curvature of the reproducing jewel, Figure 2 is a plan of an example of practical means for producing according to my invention a record from a master record, which words are hereinafter to be taken as including a replica of a master, and Figure 3 is a side view of the mechanism shown in Figure 2.

In Figure 1 a sphere or disk A is shown in contact with a sine curve B. I will assume for the sake of clearness that the curve B lies in a vertical plane. Then as the sphere moves along the curve B its highest point will trace out the curve C. It

is at once obvious that the curveC is not similar to the curve B. In order that the difference between the curves B and C may be the more apparent to the eye I have added to the diagram a dotted curve D which is similar to the curve B. It will be seen that a valley or dale in curve B becomes in curve C a steeper hill and that a hill in curve B becomes a flatter or squarer dale in curve C. If therefore we consider the curve B to be a sound track in a record and the sphere A to be a reproducing jewel the sound wave produced will be represented by the curve C and will be distorted from the true curve B which it is desired to reproduce. If, on the other hand, the jewel be caused to travel along the curve C, its lowest point will trace out the curve B.

These facts may be made more apparent from the following considerations. With the jewel A in the position shown in Figure 1, its highest point is assumed as connected to the sound box. The lowest point, or the opposite end of the diameter, is in contact with the curve. But, suppose this circle A to travel up the left hand side of the curveB. The contacting point of the circle A with the curve B will vary, lying somewhere in the lower left hand quadrant of the circle, and the point connected to the sound box, which is the point through which the vertical diameter passes, will trace the curve C. As has been stated, this is not similar to the curve B, hence the sound will not be an exact reproduction of that originally recorded.

However, if a record is produced having the distorted inverse curve C, and a reproducing jewel is made to travel along this curve, the lowest point, then assumed to be connected to the sound box, will trace out the original curve B. In other words, if the circle A travels along the right hand side of the curve in Figure 1, the point at which the vertical diameter cuts the lower side of the circle will trace out the curve B, which is the original curve.

According to my invention therefore I produce from a master a record having a sound track which is a distorted inverse of the track on the master, in other words, the jewel employed to produce the sounds is caused to run on the under side of curve C instead of on the upper side of curve B so that the sound corresponds to curve B. Such a distorted inverse record is produced by cutting the surface of a wax blank, which may be a cylinder or disk, by an engraving stylus or point which is actuated by direct thrust from a tracing stylus or disk pressed against the sound track of the master. The blank is then electrotyped and used in the ordinary way to produce a matrix from which duplicates are milled or pressed. I find that the best results are obtained by employing a reproducing jewel of a fairly large diameter because a small one limits the amount of sound that can be produced from a record and is more liable to become worn and in addition is apt to emphasize unduly any natural imperfection of the record which forms no part of the control over the diaphragm of the sound box.

Preferably I employ a large cylinder as master and make the distorted record smaller, that is, of a diameter less than half that of the master and I have found that the ratio of the diameter of the disk in contact with the master to the diameter of the reproducing jewel should vary with the square of the ratio of the surface speed of the master to the surface speed of the distorted record, tha-t'is, if both are cylinders rotated with equal angular velocities, "with the square of the ratio of the diameter of the master to the diameter of the distorted cylinder. For instance, the master is a cylinder 4 inches in diameter; this is traced with a sapphire jewel of 2 ms. diameter on to a cylinder 2 inches in diameter from which the sound is produced by a sapphire or diamond of 0.5 mms. diameter.

Referring to Figures 2 and 3, a lever 5 having trunnions 16 pivoted at'6, 6, carries a .tracing jewel 1 and an engraving stylus 7 The jewel 1 is pressed against the surface of a master cylinder 2 by a spring 8 connected to the lever 5 and to a pin 9, so that the movements of the lever about its pivots owing to the sound track on cylinder- 2 cause the stylus 7 to engrave upon the cylinder 3 a distorted inverse of the track on cylinder 2. Referring backfor the moment to Figure 1, if the curve or cylinder 2 is the curve B, the curve on cylinder 3 will be the distorted inverse curve C. The pivot 6 of the .lever 5 is carried by a bracket 10 itself pivoted at 11, 11; the axis 12 of these pivots 11 passing through the point of contact of the jewel 1 with the cylinder 2. Hence the force pressing the jewel on to the surface of the master does not sensibly constrain the. freedom of rotation about the axis 12. The pivots 11 are mounted on a block 13 which is free to.

rotate about an axis 14 at right angles to the axis 12 in order that the jewel may be able to follow the track in cylinder 2. On a threaded portion of the bracket 10 is mounted a counterbalance weight 15 by moving which towards or away from the axis 12 the depth of cut of the stylus 7 can be regulated. It will be noticed from F igure 3 that the stylus 7 is not in direct line with the jewel 1 but is displaced to one side. This is done so that should the bracket 10 be turned about the axis 12, the stylus'may be engaged with or disengaged from the wax of cylinder 3. Y

It will also be observed thatthe' tracing jewel 1 is disk shaped in order that while the diameter of the jewel may be sufficiently large to give the desired effect still the jewel will fit the fine sound track of the master.

What I claim is 1. A method of making a sound record, which consists in producing from a master sound record a record having a sound groove which is a definitely distorted inverse of the groove on the master record.

2. A method of making a sound record, which consists in tracing the impressions of a master record by means of a tracing stylus which is spherical or disk shaped and engraving on a blank of smaller size than the master a distorted inverse of the impressions by means of the action of the tracing stylus on an engraving stylus.

3. A method of making a sound record, which consists in tracing the impressions of a master record by means of a tracing stylus which is spherical or disk shaped and engraving on a' blank the diameter of which is not greater than half the diameter of the master, a distorted inverse. of the impressions by means of the action of the tracing stylus on an engraving stylus.

4. A method of reproducing sound which consists in causing a master record to move beneath a tracing stylus which is spherical or disk shaped, and engraving upon a blank,

which is caused to move at a slower surface a speed than that of the master record, a distorted inverse of the impressions by means of the action of the tracing stylus on an engraving stylus.

5. A method of reproducing sound, which consists in tracing the impressions of a master record by means of a tracing stylus, engraving a distorted inverse of the impressions by means of the action of the tracing stylus on an engraving stylus and produc ng a replica of the engraved blank, such repllca being adapted to operate a sound box through a reproducing stylus the radius of curvature of which is to the radius of curvature of the tracing stylus substantially in the inverse proportion of the square of the ratio of the surface speed of the master during recording to the correct surface speed of the replica during reproduction. v

6. A method of reproducing sound which consists in tracing the impressions of a master record by means of a tracing stylus, engraving a distorted inverse of those 1mpressions by direct thrust fromthe tracing stylus acting on an engraving stylus and producing'a replica of the engraved blank, such replica being adapted to operate a sound box through a reproducing stylus the radius of curvature of which is to the radius of curvature of the tracing stylus substantially in the inverse proportion of the s uare of the ratio of the surface speed 0 the master during recording to the correct surrotation about an axis, a blank capable of rotation about an axis, a lever pivoted to turn about an axis substantially parallel to the axis of the master record, a tracing stylus carried by the lever, an engraving stylus also carried by the lever, and a bracket supporting said lever and mounted to turn about an axis at right angles to the pivoted axis of the lever and which passes through the point of contact of the tracing stylus With the master record.

8. Mechanism for producing a sound record comprising a master record, a blank, and a lever pivoted to turn about substantially parallel axes, a tracing stylus carried by the lever and an engraving stylus also carried by the lever in olfset relation to said tracing stylus, a bracket supporting the lever and mounted to turn about an axis at ri ht angles to the axes above recited and Which passes through the point of contact of the tracing stylus with the master record, and means for varying the pressure of the engraving stylus on the blank.

In testimony that I claim the foregoing as my invention I have signed my name this 19th day of November, 1920. Y

ADRIAN FRANCIS SYKES.

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