IMPROVEMENTS IN TELEPHONE RECEIVERS
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
We GEORGE HENRY BASSANO, Warner 'Street Derby in the county of Derby,
Electrician, ALBERT EDWARD SLATER Gerard Street Derby in the county of
Derby Electrician, and FREDERICK THOMAS HOLLINS Colville Street Derby in the
county of Derby, Clerk, do hereby declare the nature of our joint invention for
IMPROVEMENTS IN TELEPHONE RECEIVERS to be as follows:-
In Letters Patent No 1290 of March 10th 1883 a Telephone Receiver is there
described in which the usual tympan is dispensed with and a disc or plate not
attached round its circumference is fixed to a suitable spring or holder and an
armature the whole actuated by an electro-magnet:
Now under this Patent we prefer to dispense with the form of spring and
armature or armatures there described and to use a more simple and effective
arrangement-the mere torsion or twist of a piece of wire or strip of metal being
used to keep the vibrating plate in a state of tension. Two simple bar armatures
are fixed on centres or hinges from opposite points their loose ends hanging over
the pole or poles of an electro-magnet and kept in a state of tension by means of
a piece of wire or strip of metal connecting them together-When the armatures
are attracted by the electro-magnet each armature being centred at opposite points
gives the, wire or strip of metal a twist in opposite directions and when the
armatures are released they fly back sharply into their normal position merely by
the untwisting of the wire or strip of metal-This wire or strip of metal which is
preferably of steel has a pin screwed, brazed, or otherwise secured, to its.centre
between the two armatures, forming practically a T piece -the pin serving to
carry a disc or plate of preferably non-inductive material such as pine-The effect
of this is that the disc or plate (which is fixed in a cylinder or recess or air
chamber) has an equal amplitude of vibration at all points of its surface when
actuated by an electric current being sent round the electro-magnet-A single or
double pole magnet or electro magnet may be used-If a single pole is used part
of each armature is cut away so that the one shall fit in with the other and both
thus be over the one pole piece.

page_text: The torsion of a piece of wire or strip of metal may be used with advantage to
give a disc or plate a tongue movement, the plate being attached at one end and
free at the other-A piece of wire or strip of metal is attached across the end of
a tongue of either inductive or non-inductive material the same as the axle of an
hinge but fast instead of loose and the free ends of the wire or strip of metal
soldered or otherwise attached to fixed supports so that on any movement of the
tongue the wire or strip of metal will twist and untwist and so that the tongue
cannot be moved without twisting the wire or strip of metal.

page_text: We GEORGE HENRY BASSANO, Warner Street, Derby in the County of Derby,
Electrician, ALBERT EDWARD SLATER, Gerard Street Derby in the County of
Derby, Electrician, and FREDERICK THOMAS HOLLINS, Colville Street Derby in
the County of Derby, Clerk, do hereby declare the nature of our joint invention
for IMPROVEMENTS IN TELEPHONE RECEIVERS and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement:-
>
Under this patent we prefer to dispense with the form of spring and armature
or armatures described in Letters Patent No 1290 of March 10th 1883 and to use
the mere torsion or twist of a piece of wire or strip of metal to keep the vibrating
disc or plate in a state of tension.
Two simple bar armatures are fixed on centres or hinges from opposite points,
their loose ends hanging over the pole or poles of an electro-magnet and kept in
a state of tension by means of a piece of wire, or strip of metal, connecting them
together.
This wire or strip of metal (which is preferably of steel) has a pin screwed,
brazed, or otherwise secured to its centre between the two armatures, forming
practically a T piece-the pin serving to carry a disc or plate of preferably non-
inductive material such as pine-A single or double pole magnet or electro-magnet
may be used with this form of armature or armatures.
Figs 1. 2. 3 and 4 of the accompanying drawings have reference to our improved
armature fitted and arranged suitably for a double pole or horse shoe magnet or
electro magnet and also indicates the form of magnet preferably 'used.
•
Figs 5. 6. 7 and 8 refer to our improved armature to be actuated by one pole of
a single or compound magnet or an electro-magnet.
- Figs 9 and 10 show a modification of the bar armature-to which however we
make no special claim except so far as it is within the claiming clauses of this
specification.
The armatures are in every case shown fixed on centres, but obviously may be.
fixed on an hinge, or in any other suitable manner which will allow (at that part).
of the movement of the armature as upon an axis-Corresponding parts are
indicated by similar letters.
.
Fig 1 is a plan of the double armature or armatures kept in a state of tension
by a piece of wire (preferably steel) attached to each of the two armatures-
Figs 3 and 4 indicate in plan similar armatures connected by a strip of metal-in
Fig 3 the strip of metal is attached with its flat or broad si le to the face of the
armatures, whilst in Fig 4 a similar strip of metal is attached edgeways as
indicated.
Now a is a metallic rim having an outer ridge or collar (shown in section at a
Fig 8) having four ears or projections b. b. b. b (also shown in section at 6 Fig 8)
between which rest the soft iron or steel armatures C. C. held upon centres f.f.f.f.
d Fig 1 is a short piece of wire (preferably steel), which with the pin e (seen in
section Fig 7) forms a T piece-The ends of the wire d, which are squared; pass
through holes in the armatures C. C and are riveted, soldered or otherwise secured
just at the ends of the wire d so that the greater part of the wire, even where'
passing through the armatures, is free to twist, whilst the wire is rigidly secured to
both armatures-The pine which has a screw thread is fitted with a washer h, and

page_text: "
nuti (Fig 7) between which is placed a disc or plate of non-inductive material
such as pine, ebonite, mica, horn or ivory and sufficiently thick as not to act as
a flexible tympan-see K Fig 8.
Now when the magnet M (Fig 2) having a coil of insulated wire A. A on each
pole is brought near the armatures C. C. the armatures are pulled or attracted out
of their normal position, and being centred at opposite points, each of the armatures
twist the wire d in opposite directions; and when the magnet is withdrawn, or the
polarity of the magnet altered or reversed by a current of electricity passing
through the coils A A the armatures C. C. are released, and, by the untwisting of
the wire d, fly sharply back into their normal position-As the pin e, attached to
the centre of the wire d, carries the disc K (Fig 8) every time the armatures CO
are attracted or pulled out of their normal position, a rarefaction of the air takes
place in the recess or cylinder formed by the cap or lid N of the case O (Fig 8)
and when released, the disc K, moving sharply back to its normal position, causes
a condensation of the air-Therefore a varying current of electricity passing
through the coils AA causes through the movement of the disc K, varying
condensations and rarefactions of the air in the cylinder or recess described.
Figs 3 and 4 are precisely the same as Fig 1 except that the armatures are held
by strips of metal d, instead of a piece of wire-in both cases the torsion of the
metal results from the movement of the armatures.
Fig 2 shows the form of magnet preferably used with the form of armatures
indicated in Figs 1. 3 and 4.
Figs 5. 6. 7 and 8 show the armatures made and fitted to be actuated by only
one pole of a magnet or electro-magnet-Fig 5 is a plan showing the rim,
armatures etc Fig 6 is a section of the armatures C. C.-Fig 7 is a sectional view
of the piece of wire d and pin e and Fig 8 the complete Telephone Receiver in
section fitted with a compound magnet—În Fig 5, a, as before, is the metallic rim
having projections or ears b. b. b. b. fitted with screws ffff holding the arma-
tures C. C.-It will be seen that part of both armatures is cut away so that both
may be over and within the magnetic field of the one pole of the magnet_The
piece of wire d is secured at its extremities to the armatures C. C. as previously
described.
•
In Figs 6 and 7 (sectional views) h is a brass washer and i a small nut on-the
"pin e.
Referring to Fig: 8 (which is a sectional view of the complete instrument) A is
the coil of insulated wire as before, fitted on the pole-piece of the compound.
magnet M-C. C. are the armatures, d the piece of wire (preferably steel), e the pin
carrying the washer h, disc K, and nut i; b. b. show two of the ears or projections
of the rim a, holding the armatures C. C.-The disc K is secured by its centre to
the pin e by the nut i and (as described in our before recited patent No 1290 of
March 10th 1883) we sometimes prefer to attach to the edge or circumference of the
disc K a ring 17 of thin flexible air-tight material such as leather, oil silk, macintosh,
india-rubber, etc, held by a rim or ring pp of brass or other suitable material,
which in its turn is held down by the cap N-This flexible air tight material is
not necessary to the working of the instrument but improves its efficiency-making.
the condensations and rarefactions of the air in the cylinder or recess more marked.
The other parts of Fig 8 will be understood. O is the case (of a well known
portable form), t t are the terminals of the instrument and a the screw for
regulating the distance between the pole of the magnet and the armatures.
The object of this arrangement of armature to carry the disc K is that there
shall be no bending of any metal or other material when actuated-but that the
torsion of the wire or strip of metal shall alone be the spring by means of which
the armatures and disc are kept in a state of tension.
As is well known when metal or other material is set in. vibration it gives
out musical tones which when it is used (as a free tongue for instance) as the
active part of an articulating Telephone Receiver considerably interferes with the

page_text: distinctness of the articulation-By merely using the torsion of a piece of wire or
strip of metal this musical tone is almost if not entirely done away with.
The disc K is also, by the means herein employed-given a straight parallel
movement each part of the surface of the disc having an equal amplitude of
vibration, as contradistinguished from a tympan which only vibrates at its centre
and is immovable at the edge where it is bound and held as a, tympanum or
drumhead.
Having now particularly described and ascertained the nature of our said
Invention, and in what manner the same is to be performed, we declare that what
we claim is:
1. In a Telephone Receiver the combination of two bar armatures held in a state
of tension by means of a piece of wire or strip of metal in the manner and for the
purpose substantially as set forth and described.
2. In a Telephone Receiver a disc or plate of non inductive material held by its
centre by means of a pin, or equivalent, in combination with two armatures
connected by a piece of wire, or strip of metal, substantially as described and
illustrated in the accompanying drawings.
3. In a Telephone Receiver the two bar armatures and the T piece connecting
them, in combination with an electro- or permanent magnet for the purpose and in
the manner substantially as set forth and described,