Improvements relating to Electric Lamps and to Apparatus connected therewith.
Year: 1892

page_text: Date of Application, 29th Dec., 1892
Complete Specification Left, 27th Oct., 1893-Accepted, 2nd Dec., 1893
PROVISIONAL SPECIFICATION.
Improvements relating to Electric Lamps and to Apparatus
connected therewith.
I ALFRED LYSTER SHEPARD of 8 West Kensington Gardens in the County of
Middlesex, Electrical Engineer do hereby declare the nature of this invention to
be as follows:-
My invention relates to electric lamps and to apparatus connected therewith.
My said invention is specially applicable to arc lamps for photographic, stage &
optical lantern work.
In carrying my said invention into practice, I provide a small electric motor to
operate the carbons, having an armature of the Pacinotti or other suitable type,
the fields for which are constructed of specially soft iron, and are wound with fine
wire coupled as a shunt on the arc, they are moreover of such a size compared
with the magnetizing effect of the ampère-turns upon them as never to be wholly
saturated, rendering them thereby very sensitive to changes in the potential of
the arc.
A special feature of my said invention consists in utilizing the field-magnets of
the motor for the double purpose, firstly of supplying a magnetic field for the
armature, and secondly as a relay by causing them to attract, against the pull of
an opposing spring or weight, a bar of soft iron pivoted or otherwise arranged
between or at a suitable distance from the opposite poles of the said magnets, the
motions of the said bar being used to make or break the armature circuit by means
of suitable contacts, in accordance with the requirements of the lamp.
The armature current is obtained by shunting a portion of the current passing
through a small resistance coil placed in series with the arc, into the said armature
by means of the above-mentioned relay and contacts.
The carbon-holders are provided with screwed nuts and are driven in opposite
directions by means of a screwed shaft having a right hand thread on one portion
and a left hand thread on the other, I prefer to incline the said shaft at an angle
of twenty degrees to the vertical, the armature spindle is provided with a small
pinion wheel which gears into a toothed wheel, through the centre of which the
screwed shaft passes and is free to move vertically through a suitable distance, the
rotary motion of the armature and toothed wheel is transmitted to the screwed
shaft by means of a key-way and key.
Suitable guides are provided for the upper and lower carbon-holders, fixed to the
frame of the lamp, I sometimes use these guides suitably insulated from the frame
to convey the current to the carbons.
The guide for the upper carbon-holder also carries a support or bearing for the
upper end of the screwed shaft, the lower end of which has a long bearing on the
base of the lamp.
It is sometimes necessary to raise or lower the arc, relatively to the focus of
the apparatus in which the lamp is in use, in order to do this a milled nut, provided
with a locking device, is screwed on to the upper extremity of the screwed shaft
above the upper support, which nut, being turned relatively to the shaft, raises or
lowers both it and the carbon-holders together. Although I have hereinbefore
described a convenient and advantageous method of carrying my invention into
practice, it is obvious that I can somewhat modify the construction of my apparatus
without in any way departing from the nature of my said invention.
December 29th 1892.

page_text: COMPLETE SPECIFICATION.
Improvements relating to Electric Lamps and to Apparatus
connected therewith.
I, ALFRED LYSTER SHEPARD of 8 West Kensington Gardens in the County
of Middlesex, Electrical Engineer 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 and by the following statement :-
My invention relates to electric lamps and to apparatus connected therewith.
My said invention is specially applicable to arc lamps for photographic, stage and
optical lantern work.
In carrying my said invention into practice I provide a small electric motor to
operate the carbons having an armature of the Pacinotti or other suitable type,
the fields for which are constructed of specially soft iron and are wound with fine
wire coupled as a shunt on the arc, they are moreover of such a size compared
with the magnetizing effect of the ampère-turns upon them as never to be wholly
saturated, rendering them thereby very sensitive to changes in the potential of
the arc.
A special feature of my said invention consists in utilizing the field-magnets of
the motor for the double purpose, firstly of supplying a magnetic field for the
arinature, and secondly as a relay by causing them to attract, against the pull of
an opposing spring or weight, a bar of soft iron, pivoted, or otherwise arranged
between, or at a suitable distance from the opposite poles of the said magnets, the
motions of the said bar being used to make or break the armature circuit by means
of suitable contacts in accordance with the requirements of the lamp.
The armature current is obtained by shunting a portion of the current passing
through a small resistance coil placed in series with the arc, into the said armature
by means of the above-mentioned relay and contacts.
The carbon-holders are provided with screwed nuts and are driven in opposite
directions by means of a screwed shaft having a right hand thread on one portion
and a left hand thread on the other, I prefer to incline the said shaft at an angle
of twenty degrees to the vertical, the armature spindle is provided with a small
pinion wheel which gears into a toothed wheel, through the centre of which the
screwed shaft passes and is free to move vertically through a suitable distance, the
rotary motion of the armature and toothed wheel is transmitted to the screwed
shaft by means of a key-way and key.
Suitable guides are provided for the upper and lower carbon-holders, fixed to
the frame of the lamp. I sometimes use these guides suitably insulated from the
frame to convey the current to the carbons.
The guide for the upper carbon-holder also carries a support or bearing for the
upper end of the screwed shaft, the lower end of which has a long bearing on
the base of the lamp.
It is sometimes necessary to raise or lower the arc, relatively to the focus of the
apparatus in which the lamp is in use, in order to do this a milled nut, provided
with a locking device, is screwed on to the upper extremity of the screwed shaft
above the upper support, which nut, being turned relatively to the shaft, raises or
lowers both it and the carbon-holders together.
In the accompanying drawing I have shown how iny said invention may be
conveniently and advantageously carried into practice.
A. shows the armature of the motor on the spindle of which is a small toothed
wheel arranged to gear with the large toothed wheel K. E & E¹ are the brushes
of the armature. H. H. are the field magnets wound with fine wire and connected
in shunt on the arc. N. S. are the two poles of the magnets between which the
armature revolves, and which serve also to attract the soft iron bar B against the
pull of an opposing spring, thereby causing the tongue C. to approach the contact D.

page_text: G. is a small coil of wire of suitable resistance placed in series with the arc, when
the contacts C & D touch by reason of the increased potential of the arc above
the normal and consequently of the increased pull on B. a certain proportion of the
current flowing in G. is shunted by means of the contacts through the armature,
causing it to turn in such a direction as to bring the carbons together, I sometimes
make use of a second contact below the tongue C and by connecting the brush EI
to the centre of the coil G and the second contact to the positive side of the coil G
by this arrangement the armature will rotate in either direction according as the
tongue C touches either the upper or lower contact.
F&F are metal nuts fixed to the carbon holders but insulated therefrom which
are driven in either direction in accordance with the motion of the screwed
shaft N'. I & J are the two guides fixed to the frame of the lamp L, which serve to
keep the carbon-holders from revolving with the screwed shaft; the upper guide I
is also used to convey current to the positive carbon-holder. O' is a milled nut
screwed on to the upper portion of the shaft N¹ above the top bearing, for the
purpose either of imparting a lateral movement to the shaft N, relatively to the
lamp, or, when locked to the shaft by the nut O, of affording a convenient means
of adjusting the position of the carbons relatively to each other by hand.
M. is a long bearing on the base of the lamp, which allows of the lateral adjust-
Inent of the shaft N' and which serves also to support the wheel K, the motion of
which is transmitted to the shaft N' through the medium of the keyway H'.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
First. An improved electric arc lamp controlled by a combined motor, and relay
substantially as and for the purposes specified.
Second. In an electric arc lamp a motor, the field magnets of which are wound
with fine wire shunted on the arc, and are used for the double purpose, firstly, of
providing a magnetic field for the armature, and secondly, for operating the
lever of a relay substantially, as herein-before described, and for the purposes
specified.
Third. The improved electric are lamp constructed substantially as described
with reference to the accompanying drawing, and operating as above specified.
Dated this 26th day of October
A. L. SHEPARD.