Improvements in Sound Recording and Reproducing Apparatus
Year: 1898

page_text: Date of Application, 24th June, 1898-Accepted, 30th July, 1898
"
Improvements in Sound Recording and Reproducing Apparatus."
I, ELDRIDGE REEVES JOHNSON, of No. 108 North Front Street, City of Camden, State of
New Jersey, United States of America, Machinist, do hereby declare the nature of
this invention and in what manner the same is to be performed to be particularly
described and ascertained in the following statement :-
My invention relates to certain improvements in sound recording and reproducing
machines, and bas for its object to improve and simplify the construction of the
recording and reproducing mechanism especially that relative to the diaphragm,
stylus and connections, as more fully set forth hereinafter.
In the construction of sound recording and reproducing machines heretofore
invented great difficulty has been experienced in providing a construction in which
the sound waves are accurately recorded and reproduced.
After careful study and experiment I have discovered the cause of the difficulties
heretofore experienced and have invented the device as hereinafter described which
obviates the difficulties heretofore experienced, and produces most satisfactory results.
To remedy these defects heretofore existing, and to provide a novel
construction which shall produce more satisfactory results in sound recording and
reproducing machines are the main objects of my invention.
In the accompany drawings:-
Fig. 1 is a sectional elevation of a portion of a sound recording and reproducing
machine embodying my invention.
Fig. 2 is an exaggerated sectional diagram illustrating the edge and sides of the
diaphragm in its normal position in relation to the casing and the adjacent parts.
Fig. 8 illustrates a modification of the supporting mechanism of the stylus bar.
Fig. 4 illustrates broadly my invention showing the diaphragm supported loosely
in the casing upon the spring mounted stylus bar.
Fig. 5 illustrates another modification in construction relative to the attachment
of the stylus bar to the diaphragm.
Fig. 6, 7 and 8 are enlarged detail views of some of the forms of spring supporting
plates which are employed for supporting and securing the stylus bar in position
upon the diaphragm frame.
Referring to the drawings, A represents the tubular section of the diaphragm
supporting frame connected at one end to a recessed diaphragm holding disk, B, and.
Pin 71

page_text: its opposite end leading and connected directly or indirectly to a mouth-piece
trumpet, or similar conveying device.
In the front face of the disk, B, is formed a recess, b, on the outer edge of which is
preferably placed a ring, d, of rubber, or other suitable yielding material, which-is
preferably--normally--ont-of-close contact with--the--adjacent--edges--of--the
diaphragm, D, bat-against-which-the-said-edges-of-the-diaphragm-may-bear-under
strain, or against which the said edges of the diaphragm mar D lightly rest, but so
as not to interfere with the vibratory movement of the diaphragm as hereinafter
described. On the outer face of the diaphragm is placed a second ring, d¹, of rubber,
or like suitable material, preferably also slightly-out-of in contact with the surface
of the diaphragm as above described, the said ring being held in position preferably
in the disk, B, by the flange disk, E, which is secured in any desired manner, as by
the screws, c, or other suitable means to the said disk, B. These-rings-operate
principally-as-retaining-rings--to--prevent-displacement--of-the--diaphragm--under
violent-strain;-though they may be omitted. The periphery of the diaphragın is
also at some little distance from the inner wall of the recess, b, the diameter of the
diaphragm being less than the diameter of the said recess; in practice the periphery
of the diaphragm would at all points be about four one hundredths of an inch from
the walls of the recess.
The supporting plate, H, for the stylus bar is secured at one end to the periphery
of the disk, B. as through the medium of the screw, g, as illustrated in Figs. 1
and 23, or by other suitable means. This plate is a spring plate tensioned to
support the stylus and bar as well as the diaphragm, as hereinafter particularly
pointed out, and at its outer end is secured to or integrally connected with the stylus
bar. This plate H, may be differently formed, as, for instance, in the manner
illustrated in the different figures of the drawing; it may be constructed in the form
as illustrated in Fig. 1 with the two block-like extremities, h, h¹, connected by the
integral plate, h², reduced to the desired thickness to produce the proper tension, or as
illustrated in Fig. 3,in which the block-like portion, h',is made integral with the plate, h²,
the latter being of considerable length and slotted at 45 h³, for the passage of the
securing screw, g; in this construction the plate, h2, passes through slot, ht, formed in
the centre of the block, h, which latter is also provided with a slot, h³ h³, in line with the
slot, h, for the passage of the securing screw, g. This construction provides for an
adjustment of the block, h, upon the plate, h2, or vice versa, to regulate the tension of
the plate, h. It is also obvious that the plate may be constructed as a plain spring
plate, as illustrated in Figs. 4 and 5. The spring plate may also be constructed in
the manner illustrated in Figs. 6, 7 and 8, with the grooves, h, on either or both
faces or at the sides, as indicated, the depth and breadth of the groove regulating
the tension and sensitiveness of the spring plate. In the construction shown in
Fig. 8 opposite ends of the plate are bent at an angle to each other; in this
construction the securing screw, g, is passed through the orifice, h', while the portion
to which the stylus bar is secured is, when in position, on a line parallel with the
stylus bar and secured thereto.
The stylus bar at one end is recessed for the reception of the needle, or stylus, k,
which is held in position by a set screw, 12. The opposite end of the bar is curved or
bent to a substantially right angle to its length and has, preferably, a slightly
enlarged head, i, which is connected to the diaphragm by elastic cement, i¹. In
adjusting the stylus bars to the diaphragm much care must be taken.
preferably provide at a suitable point in the length of the stylus bar a guard, M,
secured by screw, m, to the flange, E, preferably in the manner indicated in Fig. 1
to protect the stylus and prevent it from being torn from the diaphragm by accident.
The said guard having at its centre a slot, m', through which passes the stylus bar, I,
the distance between the side walls of the slot and the stylus bar being about
one hundredth of an inch so that the lateral movement of the stylus bar to any
greater extent than this is absolutely prevented. The vibration of the diaphragm
beyond the normal limits is prevented in one direction by the outer wall of the

page_text: slot, m³, and in the other direction by adjustable stop screw, n, provided in the adjacent
wall of the guard, M, at a point within the slot, and immediately ander opposite the
stylus bar.
In the construction illustrated in Fig. 5 the upper end of the stylus bar is
connected to the diaphragm adjustably through the medium of the screw threaded
pin or bar, f, regulated to bear on its inner end on the diaphragm as desired.
In my improved construction, as illustrated and described, it will be noted that
the edges of the diaphragm, D, are practically free within the frame, B, and
normally out of such contact with the adjacent surfaces as would interfere with the
vibration of the diaphragm in its entire area, the diaphragm being supported from
its central point upon the upper end of the stylus bar, which is supported upon the
frame through the medium of the spring plate. The diaphragm is, therefore
fore, free to vibrate throughout its entire area uniformly under the impulse of the
sound waves, or the waves of the reproducing medium, the spring plate, H, tending
always to yield under the vibratory influence of the sound waves, or reproducing
medium, and to return the diaphragm to its normal position when at rest.
To obtain the best results and to produce pure musical notes loud, distinct and
clear the diaphragm should move as a whole in recording and reproducing, and not
be rigidly confined at its peripheries in such a manner as to make it a round spring
in which the vibratory movement is greatest at the stylus contact or centre.
purely centre vibration is undesirable and operates as a great disadvantage both in
recording and reproducing, and does not produce the full volume of sound.
This
In the drawings the distance between the surface of the edges of the diaphragm
and the adjacent surfaces of the rings, d, d' are illustrated in a-somewhat un
exaggerated degree. The--distance--between--the--said surfaces; is practically
immaterial-so-long-as-the-said-tree-vibratory-movement-of-the-diaphragm-through-
out-its-entire-area is not interferred--with-to-this- extent this-distance--may-be
lessened-and-varied;-and, as As a matter of fact a-portion-of-the-surface-of the
rubber rings may actually touch a-portion-of the surface of the diaphragm without
materially interferring with the this free vibratory movement throughout the entire
area of the diaphragm, though the contact impact must be very slight, if-at-all.
It will be further noted that, as the fulcrum point of the stylus bar tends in
operation, by reason of the construction described, to slightly yield and vary, the
diaphragm must also for this reason he sufficiently free at the edges to allow the
plane of the diaphragin to accommodate itself to the changing fulcrum point.
It will also be noted that in constructions where the diaphragm is secured at its
edges, or held under strain at these points, the diaphragm itself operates as a spring
to return itself to its normal position when at rest. In my improvements, as herein
described, as the diaphragm is practically loose in its casing, and free to vibrate
throughout its entire area, it is necessary that it be supported in the casing through
an external medium, as to wit, the stylus bar, and also that an externally located
spring be provided to return the diaphragm to its normal position in the casing
when at rest, the said spring being properly tensioned to allow the diaphragm to yield
under the impulses of the sound waves, or recording medium, and to return the
diaphragm to its normal position when these impulses have ceased.
The apparatus which I have berein described in detail embodies my invention in a
practically working form, though the construction may be varied without departing
from the spirit of my invention.
Having now particularly described and ascertained the nature of my invention
and in what manner the same is to be performed, I declare that what I claim,
8-
1. In-a-sound--recording-and-reproducing-machine--a--diaphragm-loosely
mounted in its cocinc
1.

page_text: spring-supporting said-stylus -bur constructed-to-normally retain-the--diaphragm
when-at-rest-loosely-in-the-easing in its normal-position--and--to-respond--under
vibration-produced-in-recording or transmitting sound, substantially-as-described.
2. In-a-sound recording-and--reproducing--machine, a stylus-bar--and point
rigidly-connected throughout-their-combined-length-and-disposed-on-a-line with
the face-of-the--diaphragm,-the-upper-end of the stylus bar-being-attached-to-the
diaphragm, a counterbalancing-spring-plate-supporting-said-bar-intermediate in its
length-for-counterbalancing the-momentum of the stylus bar-and-a-diaphragm
loosely-mounted in its frame attached at its contral-point-to-the-stylne-bar-and
adjusted-to-yield throughout-its-entire-area- approximately evenly to the impulses
of-the-sound-waves-in-recording, and-to-the-vibrations-of-the--stylns-in-the- repre-
duction-of-sound waves, substantially-as-described.
3. In a sound-box-for-sonnd-recording-and-reproducing-machines-a-stylus--bar
mounted-on-a-yielding-fulerum, a diaphragm-loosely-mounted--in-its--easing--said
diaphragm-being-seenred-about-its-centre-to the upper end of the stylus-bar-being
loosely-mounted-to-allow-its-edges-a-slight play to accommodate the-position-of-the
diaphragm-to-the-respective-changes-in-position-of-falerum-occasioned-by-the-slight
yielding-of-the-same.
4. In-a-sound--recording--and--reproducing--machine,--the--combination--of-the
diaphragm-loosely-mounted-in-the-frame-of-the-machine,-a-stylus-bar--secured--at
one-end-to-the-eentre-of-the-diaphragm-and-tending to-support--the same, a stylus
bar-support-secured to-the-frame of the machine-and-to-the-etylus-bur--at-opposite
ends, respectively, caid support-comprising a yielding or spring plate having its cross
seetienal-area-reduced-at-about-midway--of-its--length-to--govern--the--maximum
vibration,-the-extent-of-such-reduction being-in-direct-proportion to the--character
or-pitch-of-the-notes-to-be-recorded-or-reproduced.
5. A Fielding stylus-bar-support-for-cound-recording-and-reprodueing-machines
comprising-a-metallic-plate-having-an-enlarged-head-adapted-to-be-secured--to--the
stylus-bar, the opposite-end-being-adjustable-upon-a-fixed portion of-the-machine,
said-metallie-plate-being-redneed-in-thickness-through-its entire width-at-or-about
its-central-portion-for-controlling-the-maximum-vibration-of-the-stylus-bar.
6. A-Fielding-bar-support-for-sound recording-and-reproducing machines,-com-
prising-a-metallic-plate-or-block-adapted-to-be-secured-at-its--opposite--ends--to--a
fixed--point--and--to--the--stylus-bar-respectively, said-plate-or-bar-having-ite-eross
sectional-area-reduced-at about midway of its length to govern a maximum-vibration
of-sneh-stylus bar, the-extent-of-such-reduction-being-in--direct-proportion--to--the
character-or-pitch-of-the-notes-to-be-recorded-or-reproduced.
7. In-a-sound-recording-and-reproducing-machine, a stylus bar-support-per-
manently secured-at-one-end-to-a-fixed-point-and-at-its-opposite-end-to-the--stylus
bar, the-said-support-having-an-enlarged-head-at-its-point of connection--with--the
stylus-bar-and-reduced-in-aren-throughout the remainder of its length, an adjustable
block-movable-on-said-reduced-portion-toward-and-from--the--enlarged--head,--and
means-for-securing-said-block-in-any-position-to-which-it-may-be-adjusted.
S. In-a-sound-recording-and-reproducing-machine, a stylus- bar--support--com-
prising-a-vibratory plate having an enlarged-end-at-its-point-of-connection-with-the
stylus-bar-and-reduced-in-thickness-throughout-the-remainder--of-its--length, -and
having--an--orifice--in--eneh--reduced-portion-adapted-for-the-passage-of-a-seenring
screw,-a-block-of-approximately the thickness-of-the-integral--head--having----clot
through-which-the-securing-screw-may-pass, said-block-being-adjustable-upon-the
reduced-portion-of-the-plate-from-and-toward--the enlarged head-to-increase--or
decrease the-maximum-extent of vibration-in-the-
e-supporting-plate--and--se--govern
and-regulate-the-tone-or-pitch-of-the-notes-to-be-recorded-or-reproduced.
9. In a sound recording and reproducing machine, a diaphragm adapted to
move throughout its entire area, approximately evenly, in response to the impulses
given in the recording and reproduction of sound waves and supported at or near its
centre on the end of the stylus bar, and yielding rings arranged on each side of near
the periphery of the said diaphragm, said rings being so arranged as to permit of the

page_text: Borison & Ciprovements in Dound Necording and reproducing Apparatus.
free vibratory movement of the diaphragm at the point of contact with said rings,
substantially as described.
10. In a sound recordin-and--reproducing -machine--the--combination--of--the
diaphragm-supporting-ease,-a-diaphragm-therein-adapted-to--move--thronghont--its
entire-area-approximately evenly-in-response to the impulses-given-in-the-recording
and--reproduction--of--sonnd--waves-and-supported-as-or-near-its-centre-on-the-end
of-the-stylus bar, yielding-rings-arranged-on-eash-side-of-and--near-the--periphery
of-the-said-diaphragm, said--rings--being--so-arranged as to--permit--of-the--free
vibratory movement--of-the--diaphragm--at-the-point-of-contact-with-said-ringo;-a
Hanged-cap-fitting-over-the-periphery-and-a-portion-of-the-fase--of--the--diaphragm
suporting-ease-and-provided-with-peripheral-slots--and--seenring--serews--adapted
to-pass-through-said--slots--and--secure---said---eap--to---the---diaphragm---ease,
substantially-as-specified.
11. The combination-of-the-diaphragm-sapport-provided-with-a-recess--for--the
reception-of-a-diaphragm,-a-diaphragm-of-a-diameter-less-than-the-diameter-of-the
recess;-a-stylus-bar-having-one-end-secured-to-the--centre-of-said-diaphragm,-and-a
slotted-gaard-fitting-around-said-stylus--bar--and adapted--to--limit--the-range--of
vertical-and-lateral movement-of-said-stylus-bar.
1-In-a-sound-recording-and-reproducing--machine,--the--combination--of--the
the-centre-of-the-diaphragm,-a-slotted--gaard-fitting-over--said--stylus--bar,--and
stylns-bar-said-serew-and-guard-being--adapted--to--limit--the--range-of--vibratory
diaphragm-supporting-ease,-a-diaphragm therein,-a-stylus bur-seenred-at-one-end-to
adjustable-set-screw-projecting from-the-diaphragm--ease--immediately--under--the
and-Interal-movement-of-said-stylus-bar.
13.-1a-a-sound-recordin-and-reprodueing-machine--a--diaphragm--frame,--A,
having-shoulder, a, diaphragm,B,-securing-ring,--G--needle--bur,- D--supporting
plate, E, serewthreaded-connecting-pin,-/;-provided in the upper-end-of-said-needle
bar-thumb-serew,-d, provided-in-the-lower-end-of-said-needle-bar,--removable--point
or-pin, d'-substantially-as-described.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C. Agents for the Applicant.