US 1737253 A
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Description (OCR text may contain errors)
Patented Nov. 26, 1929 I v UNITED STATES PATENT OFFICE,
ALFRED -AU'BYN' LINSELL, OI BBENTWOOD,,ZENGLAND, ASS IGNOR EEO-RADIO CORPORA- TIOiN OF AMERICA, A CORPORATION OF DELAWARE I MEANS FOR RECORDING AND BEP BODUCING SOUND Application filed. September 28, 1927, Serial No.
This invention relates to means for recordmg and/ or reproducing sound, and more particularly to means for recording sound upon gramophone and the like records and/or reproducing sound therefrom.
According to this invention nieans for recording or reproducing sound comprise a piezo-electri'c crystal, means for applying otential to or deriving potential from one or more of the faces of'the crystal, and means for applying force to or deriving force from one or more of the faces of the crystal.
The piezo-electric. crystal may be employed in conjunction with a separate stylus device, such as a steel point or a sapphire, but preferablysuch stylus device is formed integral with the crystal.
In carrying out the invention for the reproduction of sound from a gramophone or the like record, a suitably cutpiezo-electric crystal is subjected to a compressive, followed in certain cases by a tensile, ing in such a manner as to produce a corresponding contraction or extension of the crystal in a plane containing any two of the principal axes thereof, the said forcebeing applied by and due to the movement of a stylus, aflixed to the saidcrystal, and in conof a piezo-electric crystal are the optical axis,
tact with, the sound trace of a phonograph or gramophone record. These principal axes the electrical axis, and the geometrical axis which is perpendicular to the optical and electrical axes.- The application of force to the electric potential, derived from two opposite faces of the crystal, either or both of which undergo the compression or tension. It will be seen that the electrical potential developed will correspond with the sound trace on the record. This potential may be amplified in any known manner, converted into sound waves by means of a telephone, r other suitable instrument.
Similarly, in the case of recording, the sound waveslafter amplification if desired are converted into corresponding electrical potentials, which are applied toopposite faces of a suitably cut piezo-electrlc crystal, thereby causing a physical deformation of the crystal,
force, actcrystal results in the generation therein of an.
andin Great Britain October 2, 1926.
which is utilized to cut a sound trace on a gramophone or phonograph record.
In one form of construction the crystal is 'mounted in a holder or carriage attached by a flexible coupling to an arm'positioned close to the record and pivoted in such a manner as to allow the carriage to move-across the record face following the course-of the sound trace. The weight, and therefore the inertia, of the carriage is such, and is so'positioned, that it provides a substantially rigidholder for the crystalin relation to the surface ofthe record, while at the same time the flexible coupling prevents any unevenness in the movement of the-record table (due, for example, to eccentricity of mounting), from affecting the crystal. Y
Although any known type of stylus, such, for example, as a steel point or sapphire, may be usedwith the piezo-electric crystal arrangements herein described, it is preferred of the pyramid being the Two examples of arrangements in accordance with the invention will now'be described. The first example relates to phonograph or pathephone reproduction.
From a piezolectric crystal such a quartz, I
a rectangular plate is. cut whose faces are parallel to the optical axis, the electrical axis, and a geometrical axis which is perpendicular to the optical, and electrical axes, respectively.
In the center of the face containing the electrical .and eometrical axes is affixed the stylus, or a ternatively, this face may be ground with a projection shaped to act as the stylus. The crystal is mounted in a carriage so that the face carrying the stylus projects freely from it, and the opposite face bears on the body of the carriage. Two rectangular electrodes are provided on the two faces containingthe optic and geometric axes, and
- these electrodes may also assist in retaining the crystal in the carriage. Other side members may also be provided for retaining the crystal in position, if desired. The carriage is joined to a pivoted arm by a rubber or similar flexible coupling, the weight of the carriage being suflicient to provide a substantially rigid holder for the crystal with respect to the record. The crystalin its carriage is then mounted above the record, with the stylus in contact with the sound trace in the usual manner. It will be clear, therefore, that the varying contour of the sound trace will cause the stylus to move in a direction parallel to the optic axis, and this in its turn, since the carriage is substantially rigid, due to its inertia, will tend to cause the crystal to expand in the direction of the electrical and accordance with the original sound trace on reproduction.
the record. v
The second example refers to gramophone This is generally similar to the example just described, but a different method of mounting the crystal is adopted, and the position of the stylus on the face of the crystal is also altered. The reason for this alteration is due to the difference between the sound trace on a phonograph or pathephone and a gramophone record, the first producing an up and down movement of the stylus, while the second gives v a side to side movement. In other respects.
the procedure isas before. The'crystal is cut in a similar manner, and the faces containing the optical and geometrical axes are again,
provi ed with electrodes, but thestylus, instead of being positioned in the center of the face containing the electrical and geometrical axes, is now positioned at the center of one of parallel to the electrical axis. The crystal with its carriage is then positionedabove the gramophone record with the side carrying the stylus in the center maklng a tangent with the circular groove of the sound trace, the stylus being of course in contact with the said trace. The resultlng movement ofthe stylus in one direction, due to the I sound trace, will therefore cause the whole or a part of the face containing the optical and. geometrical axes to contract, while movement mthe other direction will cause it to expand. This expansion and contraction will generate electrical potential as before, which may be a lified as desired. I
is to be understood that the foregoing generated.
examples are by way of illustration onl and that other arrangements may be adopted without departing from the scope of the invention. For example, the shape of the crystal has been described as rectangular but other shapes may be used, as, for instance, one in which two or more of the faces are triangular. Also the electrodes have. been de-.=
scribed as rectangular, butagain other shapes may beused, as, for instance, triangular, and the said electrodes need not be of the same shape as the faces of the crystal on which they are positioned. Again, the relative position of the axes in relation to the carriage stylus and record may be interchanged an varied.
Further, if desired, the stylus in the case of the gramophone ma be placed at any other desired position on t e face of the crystal, and not only on one side as hereinbefore described.
In one such modified arrangement the potential generated on one face of the cr stal only is utilized, and another electro e is positioned near to, but insulated from, this face, this second electrode serving as the second pole, between which and the electrode on the crystal face, the varying potential is The invention is illustrated in the accompanying drawings.
Referring to Figures 1 and 2, which show in front and side elevation respectively a piezo-electric crystal cut to a form suitable for phonograph recording and reproduction,-
l is the main body of the crystal and4 a part of the said crystal cut to form a point adapted to form, in effect, a stylus. The edge A B is parallel to the optic axis of the crystal, the edge A D parallel to the geometric axis, and the ed e A E parallel to the electric .axis thereo The part 4 may be cut to any desired degree of sharpness.
Figures 3 and 4 show in front and side elevation respectively a slightly modified form of crystal in which the part 4 is cut more abruptly.
In the modification shown in front and side elevation respectively in Figures 5 and 6, the part 4, formed in the above described constr'uctions integrally. with the main body of the crystal, is replaced by a steel stylus needle 4 of known form, clamped in a troughshaped member 2 by means ofa set screw 3, the said trough retaining the crystal 1.
Figures 7 and 8 show in front and side elevation respectively a form of crystal suit able for use in gramophone reproduction.
This form is generally similar to the forms shown in Figures 1, 2, 3'and 4, except that the part 4, which is formed integrally with the main body of the crystal, is displaced. towards the face A --H instead of being located substantially at the center of the face H. v
When such a crystal is mounted perpendicular to the surface of a gramophone record, with the part Pin contact with the trace thereof'and the face AB C D at right angles to the said trace, the said part 4 will experience forces in a direction aralleh to the edge D C. Therefore, when a to move the .part 4 to the left, the area Y ofthe crystal to the left of the line X X will experience compression, while the area Z to the right thereof will experience tension, a reversal of these forces taking place when a force tends to move the part 4 to-the right. It will be clear that under the influence of the forces, electrical potentials will be generated in,the areas to left and right of the" line X X, If therefore a pair of connected "electrodes be placed in contact with area -on the front of .the crystal and area Z on the back thereof, and a second pair of connected electrodes insulated from the first pair be'pla'ced in contactwith area Z on the front of the crystal and area Y on the back, thereof, equal potentials of opposite sign may be collected from the pairs of electrodes. These potentials may be utilized to actuate any known form of'electrical sound translating device, such as, a telephone.
In a modification (illustrated in front and side elevation respectively in Figures 7 A and 8A) of the'last described arrangement, the stylus is formed as an abrupt pomt similar 3 to that shown in Figures 3 and'4, but -d1splaced towards the face A In this case a force, tending tomove the stylus 4 to the left, will cause substantially the whole of the face-A B C D to undergo tension, wh le a force, tending to move .the stylus tothe right, will cause a corresponding compression over substantially the whole face this modification, therefore, trodes are required coverin the whole of the face A B Cv responding rear face. p
Figures 9, 10 and 11 show in front and slde elevation and plan respectively a convenient form of carriage and electrode arrangement. This arrangement, which is adapted tecarry any of the forms of crystal shown in F gures 1 to 6, comprises a metal box consisting of two halves and 6, insulated from one another by a member 9 (or by an air space rendering the said member 9 unnecessary) and carrying between them the crystal 1 which is held in position by means of screws passing through the said halves but insulated therefrom by ebonite or the like bushings 8. I In this way the box halves 5 and 6 serve the double function of retaining tlg crystal and serving as electrodes in contact with the crystal facescontaining the optic and geometric axes. If desired, the box halves 5 and 6 may substantially and the cor- 05 be insulated from the crystal faces containorce tends Y tion,
A B C D. With only two elecing the electric and geometric axes by narrow strips of mica, ebonite or the like.
It will be seen that with the arrangement shown-in Figures 9,10 and 11, if the crystal in its mounting be located above a phonograph record, with the part 4 in contact with the sound trace thereon, the said part be subjected to varying degrees of pressure in a direction perpendicular to the face of the record,and this pressure will be imparted to the body of the crystal, tending to cause the crystal to expand in a direction perpendicular to the face A B C 1),. Corresponding electrical potentials will therefore be generated on those faces which are in contact with the electrodes 5 and 6, and these potentials may be applied preferably after amplificato actuate any known form of electrical sound translating device, such as a telephone.
Figuresv 12,, 13 and 14 show in front and will 1 side elevation and plan respectively a conveni'ent form of carriage and electrode arrangement, suitable for use in gramophone recording or reproduction, with a crystal such as that shown in Figures 7 and 8. In this arrangement the carriage comprises four members' 5, 6, 5 and 6, clamped together to retain the crystal by means of screws 7 insulated by bushings 8. 9, 9, 9" are insulating members which may, however, be dispensed with if the members, 5, 6, 5, 6, are so shaped and are of such size that when in position about a crystal there'is a suflicient air spacebetween their edges to provide-the required insulation.
"Figure 15 shows in diagrammatic form a suita 1e amplifier arrangement for use with any'of the foregoing crystal arrangements.
Referring to this figure, 10 is a thermionic valve whose grid and cathode are connected across the potential generating electrodes.
For example, with the arrangement shown in Figures 9 to 11, the grid and cathode would be connected across electrodes 5 and 6, while in the arrangement shown in Figures 12 to '14, the said grid and cathode would be connected across the pairs of electrodes 5, 6' and 5, 6; '11 is an impedance connected in series with a bias battery 12, between the said id and filament. 13, 14 are the primary an secondary of a transformer, the secondary of which is adapted to actuate a telephone, loud speaker or the like .(not shown) Having now particulaiily described and ascertained the nature of .my said invention and in whatmanner the same is to be performed, I declare that what I claim is:
1. A reversible'electrical reproducer comelectro es connected to two opposite faces ofsaid body portion.
.2. In an electrical reproducer adapted to Joe rising a piezo electric crystal section, said generate electrical impulses in accordance with groove variations in a record device, a stylus shaped to fit said grooves, said stylus being formed of a 'piezo electric material.
3. In an electrical reproducer adapted to generate electrical impulses in accordance with groove variations in a record device, a piezo electric body adapted to transform mechanical vibrations into electrical oscillations or electrical oscillationsinto mechanical vibrations, and a stylus integrallyformed on said body and of the same material.
4. In an electrical reproducer adapted to generate elcctricalimpulses in accordance with groove variations'in a piezo electric crystal section orm electrical oscillations vibrations and mechanical vibrations into electrical oscillations, said crystal comprising abody portion, a stylus integral with and projecting from said body portion, and pair of electrodes connected to said body portion.
5. In an electrical ,reproducer adapted to generate electrical, impulses" in accordance with groove variations in a record device, a piezo electric crystal section comprising a body portion and a stylus integrally formed with said body portion and of the same material.
6. In an electrical reproducer adapted to generate electrical impulses in accordance adapted to transwith groove variations in a record device, a.
piezo electric crystal parallelopiped and a pyramidal extension integrally formed at one side of said parallelopiped, said extension being shaped to fit into said groove variations. 1
ALFRED AUBYN LINSELL.
record device, a-