UNITED STATES
PATENT
OFFICE.
WILLIAM G. A. BONWILL, OF PHILADELPHIA, PENNSYLVANIA.
IMPROVEMENT IN ELECTRO-MAGNETIC DENTAL PLUGGERS.
Specification forming part of Letters Patent No. 170,045, dated
November 16,1875; application filed July 21,1873.
To all whom it may concern:
Be it known that I, WILLIAM G. A. BONWILL,
of
Philadelphia, Pennsylvania, have invented an Electrical
Tooth-Filling Instrument, of which the following is a specification:
My invention relates to improvements in dental instruments
designed to be operated by electricity, the objects of my improvements
being to render the instrument compact, to adapt it to the hand of the
operator, and to facilitate the securing and the removal of the
operating-tool, and to regulate the action of the mallet. These objects
I attain by arranging the insulated coils A and A' closely
together, with the tool B at one side of or beneath the same, and
a guard, D,at the same side; by providing the instrument with a guard
or handle, D, by which it may be held in a proper position fur
operation in either the right or left hand, as shown in the plan view,
Figure 2; by so combining the tool B with an adjustable beveled pin, b,
that it can be readily removed and replaced, and adjusted from and
toward the mallet, as shown in the section, Fig. 3; and by certain
improvements in the circuit-breakers, fully described hereafter,
whereby the instrument is rendered more durable, and its operation
much facilitated.
A succession of blows, more or less rapid, is imparted to
the tool B,
which is held against the filling by a mallet, F, forming the
armature of a magnet inclosed within two adjacent coils, A and A', the
circuit being completed at one point by the hand of the operator, and
being automatically broken at another point by the mallet, which, when
attracted toward the magnet, and just before or at the moment of
striking the blow, breaks the circuit, and is then suddenly drawn back
by its spring h, the circuit
being automatically completed by a
spring-lever, H, when the mallet will be again attracted and strike
another blow, and will in like manner again break the circuit and
spring back, and so on as long as the operator completes the
circuit at the opposite point.
The tool is placed at one side of or beneath the coils,
which I arrange
close together, as shown in the diagram, Fig. 1, thus reducing the bulk
of the instrument considerably. The main object of this
arrangement is to enable the operator to hold the tool in the same
position as he would the ordinary instruments, the guard D being
arranged at one side of and below the tool, the rear end of which,
therefore, rests in the hollow between the thumb and forefinger,
the latter extending forward parallel to the stem. By this means the
automatic tool may be manipulated as readily as the usual hand-tools.
I also reduce the size of the coils and the weight of the mallet, and
yet obtain as sharp or a sharper blow with the same battery; for the
striking portion of the mallet, owing to the position of the tool, is
extended over the coils, which enables me to obtain a longer leverage,
and to strike with the end instead of with the side of the weighted
portion of the mallet. (See Fig. 3.) This lightness is also of
advantage when soft blows in very quick succession are to be struck.
If desired, the coils may be brought still closer together
by
flattening their inner adjoining sides to a greater extent than is
shown in the drawing.
Another important feature of my present invention is the
disposition of the frame E, handle E', guard D, and mallet F, in
respect
to the coils and tool, the arrangement being such as to so lower the
center of gravity in the working position of the instrument as to
enable it to rest solidly upon the operator's hand, as shown in Figs. 2
and 3. The hooked guard or handle D serves to determine the position
of and to retain the instrument in the hand, and much facilitates its
operation, the index-finger being passed through the same, if the
instrument be held in the right hand, as shown in Fig. 2, while if
it be held in the left hand the thumb is passed through the said
guard. The latter may be in the form of a ring; but I prefer that
it should be hooked. The said guard, may also, if desired, be rendered
adjustable upon the instrument.
It will be observed that the handle E', instead of being
provided
with flanges, as heretofore, is cylindrical, this also
facilitating the grasping and holding of the instrument by either hand.
The tool B is adapted to an opening in the handle E' and
frame E,
through which it can be freely passed, a spring stud or pin, b,
yielding to permit its passage, and serving as a retainer for the
same, the said pin having an abrupt edge upon one side adapted to a
shoulder, a, of the tool, and
thus preventing the latter from
being forced back upon the mallet beyond the proper point, while the
opposite edge of the said pin, which is adapted to the shoulder a' of
the tool, is beveled, as shown in Fig. 3, so as to retain the said tool
in position under
ordinary circumstances, but so that it will yield, and permit the
withdrawal of the same by a slight effort. The pin b is secured to a
plate, b', rendered
adjustable from and toward the mallet upon the
frame E, this adjustment of the plate and pin effecting also
sufficient adjustment of the tool to take up the effects of wear, and
rendering any adjustment of the parts of the mallet unnecessary,
the latter being rigid and non-adjustable throughout. The current
passes from the stud i,
through a spring, j, Fig. 4,
to a slide, G,
which the said spring has a constant tendency to force in the
direction of the arrow 1, and from the said slide through an adjustable
screw, d, casing k, and spring e to a lever, H, the latter being
maintained in contact with a screw, f,
through which the current
passes to the coils, by the said spring e.
A hard-rubber or other non-conducting projection, m, on the
mallet acts directly upon the short arm of the lever H, when the mallet
descends, and thus forces the same back from the screw f, and breaks
the circuit.
The several parts are so arranged in respect to each other
that the
circuit is not broken by the mallet until the latter has almost or
quite struck the blow, the full power of the mallet being thus
obtained, and ample time being afforded for its recoil before the
circuit is again completed by the lever H.
One end of the spring e
to which the lever H is connected, is wound
upon a screw, n, by turning
which the power of the said spring can be
increased or diminished, as desired, and consequently the rapidity of
the recoil of the lever H, and the rapidity of the blows of the
mallet, can be regulated by means of the said spring, as desired.
The screw f is
adjustable, so that the effects of wear can be readily
taken up by means of the same, and the bearings, both of the lever H
and the mallet, are also rendered adjustable for the same purpose,
and to prevent oxidization of the bearings of the lever the
current is not passed through the same, but directly to the
long arm of the lever through the spring e.
It will be observed, on reference to Fig. 4, that when the
instrument
is not in use the circuit is broken by the slide G, which is forced
away from the adjustable screw d
by the spring j; but in the
act of
forcing the tool against a filling or other object the pressure of the
index-finger or thumb upon the roughened portion of the said
slide naturally forces the same in the direction of the arrow, Fig. 2,
and thus completes the circuit without special effort on the part of
the operator.
My improved instrument, although especially adapted for
tooth-filling, can be applied in the arts generally, wherever power by
electricity is needed or can be used for actuating a hammer.
I do not claim a magneto-electric dental instrument in
which the
tool is operated by a vibrating mallet, nor the combination with such
an instrument of an automatic circuitbreaker; but
I claim as my invention -
1. An electric dental instrument, in which the insulated
coils A A1 are arranged close together, with the tool B
between and at one side, and the guard D upon the same side, and
extending beyond the tool, all as and for the purpose set forth.
2. The combination, with the instrument, of a guard or
handle, D, by
which the said instrument may be held in a proper position for
operation in either the right or left hand, substantially as
herein described.
3. The combination of the socket, open at both ends, the
tool B filling
the socket, and having shoulders a a',
and a spring-retaining pin
beveled at one edge, as and for the purpurpose set forth.
4. The retaining-pin b,
secured to and rendered adjustable upon
the frame, with a plate, b',
from and toward the mallet F,
substantially as and for the purpose specified.
5. The combination, with the said lever H, of a spring, e, the power of
which can be increased or diminished as required, and through
which the current is caused to pass, as specified.
In testimony whereof I have signed my name to this
specification in the
presence of two subscribing witnesses.
WM. G. A. BONWILL.
Witnesses:
WM. A. STEEL,
HARRY SMITH.
