Improvements in Automatic Arc Lamps used in Projectors or Search Lights.
Year: 1892

page_text: Date of Application, 4th Feb., 1892
Complete Specification Left, 3rd Nov., 1892-Accepted, 31st Dec., 1892
PROVISIONAL SPECIFICATION.
Improvements in Automatic Arc Lamps used in Projectors or
Search Lights.
We, ROOKES EVELYN BELL CROMPTON, Engineer, and EDMUND ARTHUR
NORMAN POCHIN, Engineer, both of the Arc Works, Chelmsford, in the County
of Essex, do hereby declare the nature of this invention to be as follows:-
""
Whenever
Our improved projector lamp consists essentially of a framework, placed hori-
zontally, and arranged to slide into place in grooves or guides fixed preferably to
the underside of the projector barrel, although it may be worked equally well if
fixed to one side or even with slight modifications if hung from the top of the
barrel. The framework is traversed longitudinally by a right and left handed"
screw divided into two parts in such manner that the part carrying the right
handed screw is joined to that part which carries the left handed screw by a
coupling or sleeve or any convenient arrangement which admits of the connection
of the two, but allows them to have considerable end play relative to one another,
but which forces them to rotate together. One of these screws projects at one end
of the framing and is fitted with a milled head or other convenient means causing
it to rotate, within the framing. This screw is provided with a ratchet wheel in
or "trembler" the
which engages the pawl of an electro-magnetic "vibrator
magnets of which are wound so as to be in shunt across the arc.
the vibrating portion of this trembler vibrates, it, by means of the ratchet and pawl
causes a continuous rotating movement of the screw. The other screw is fitted
with grooves or a collar which is connected to the armature of an electro-magnet,
the coils of which are connected so as to be in series with the main current. By
this last arrangement the screw is moved longitudinally by the armature of the
magnet, but it is free to rotate together with the left handed screw.
screws work in corresponding gun-metal carriages arranged free to slide on rails or
guides fixed to the main framing. To these carriages are secured arms of sufficient
length to extend to and carry the arc carbons in a position axial with the mirror or
lens of the projector. The arms themselves should be made of the most rigid
material and their cross section should be as small as possible when viewed from a
direction parallel to the axis of the projector; in other words they should offer
as little obstruction to the beam of light as is possible. At the point where they
are secured to the carriages they should be insulated therefrom.
The two
The action of the lamp is as follows:-When it is proposed to use it as a hand
feed lamp, on rotating the milled head or other rotating device attached to one of
the screws it will be seen that the two carriages can be made to approach one
another and thus bring the carbons into contact, thus completing the circuit
and allowing the current to pass through the lamp, entering at one terminal, passing
through the arms, carbons and out through the coils of the series magnet to
the other terminal. The passage of the current will actuate the armature of
The
the series magnet and thus separate the carbons and effect striking of the arc.
length of the arc must then be adjusted and hereafter maintained by rotating
the mill head by hand in the ordinary way. Should it now be desired to operate the
lamp automatically the electro-magnet trembler and pawl must be thrown into gear
with the ratchet wheel by means of a cam provided for this purpose.
This being done it will be at once evident to those accustomed to this class
of mechanism that any undue increase of E.M.F. between the two sides of the

page_text: arc will actuate the trembler and thus rotate the screw and cause the carbons to
approach one another until the desired normal E.M.F. is obtained.
Dated the 4th day of February 1892.
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Automatic Arc Lamps used in Projectors or
Search Lights.
We ROOKES EVELYN BELL CROMPTON Engineer and EDMUND ARTHUR
NORMAN POCHIN, Engineer, both of the Arc Works, Chelmsford in the County
of Essex 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 :-
Our improved projector lamp consists essentially of a framework placed hori-
zontally and arranged to slide into place in grooves or guides fixed preferably to
the underside of the projector barrel, although it may be worked equally well if
fixed to one side or even with slight modifications if hung from the top of the
barrel. The framework is traversed longitudinally by a right and left handed
screw divided into two parts in such manner that the part carrying the right
handed screw is joined to that part which carries the left handed screw by a
coupling or sleeve or any convenient arrangement which admits of the connection
of the two, but allows them to have considerable end play relative to one another
but which forces them to rotate together. One of these screws projects at one end
of the framing and is fitted with a milled head or other convenient means causing
it to rotate within the framing. This screw is provided with a ratchet wheel
in which engages the pawl of an electro magnetic "vibrator". or "trembler" the
magnets of which are wound so as to be in shunt across the arc. Whenever
the vibrating portion of this trembler vibrates, it by means of the ratchet and pawl
causes a continuous rotating movement of the screw. The other screw is fitted
with grooves or a collar which is connected to the armature of an electro magnet
the coils of which are connected so as to be in series with the main current. By this
last arrangement the screw is moved longitudinally by the armature of the magnet
but it is free to rotate together with the left handed screw. The 2 screws work
in corresponding gunmetal carriages arranged free to slide ou rails or guides fixed
to the main framing. To these carriages are secured arms of sufficient length
to extend to and carry the are carbons in a position axial with the mirror or lens
of the projector. These arms themselves should be made of the most rigid
material and their cross section should be as small as possible when viewed from a
direction parallel to the axis of the projector; in other words they should offer as
little obstruction to the beam of light as is possible. At the point where they are
secured to the carriages they should be insulated therefrom.
The action of the lamp is as follows:-When it is proposed to use it as a hand
feed lamp on rotating the milled head or other rotating device attached to one of
the screws it will be seen that the two carriages can be made to approach one
another and thus bring the carbons into contact, thus completing the circuit and
allowing the current to pass through the lamp, entering at one terminal, passing
through the arms, carbons and out through the coils at the series magnet to
the other terminal. The passage of the current will actuate the armature of the
series magnet and thus separate the carbons and striking the arc. The length of
the arc must then be adjusted and hereafter maintained by rotating the mill head
by hand in the ordinary way. Should it now be desired to operate the lamp
automatically the electro magnet trembler and pawl must be thrown into gear with
the ratchet wheel by means of a cam provided for this purpose.

page_text: This being done it will at once be evident to those accustomed to this class of
mechanism that any undue increase of E.M.F. between the two sides of the arc
will actuate the trembler and thus rotate the screw and cause the carbons to
approach one another until the desired normal E.M.F. is obtained.
In the accompanying drawings
Figure 1 gives a side elevation and part section of the lamp.
Figure 2 shows it in plan view.
Figure 3 shows it in end view looking from the positive carbon end, and
Figure 4 shows it in end view looking from the negative carbon end.
Here A shows the framework traversed by the right and left handed screw a a¹
divided at the point 6 into 2 parts, the end of the part a' being free to slide within
the female end of the part a at the sleeve connection b. c is a milled head by
which this screw can be worked by hand and d is a ratchet wheel mounted
on it and which is worked by the pawle and electro magnet f and its trembler g.
The electro magnet f is wound in shunt circuit to the main circuit which passes
through the lamp. and h¹ are the arms which carry the carbons, carrying the
positive carbon and the negative carbon. These are mounted on the carriages k
and which are free to slide on the guide and are caused to approach or recede
from one another by their nuts m and m¹ which engage with the two parts of the
screw a, a¹. n is an electro magnet wound with wire through which the main
current passes; it works the armature o which is attached to the portion a of the
Screw. When the current passes through the lamp this armature is attracted and
causes a longitudinal movement of the screw a carrying with it the nut carriage and
carbon arm m, k and h and thus striking the arc. p is a milled head which
by means of a rod works the cam r; by turning this milled head the pawl can be
thrown out of action if it be desired to work the lamp by hand by means of
the milled head c. v is a third milled head by turning this a wedge piece_s
is moved so as to vary the tension of the spring t which regulates the E.M.F.
at which the trembler comes into action and hence regulates the E.M.F. at P. P.
of the arc.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. The construction of automatic arc lamps for use in projectors consisting of a
pair of arms carrying carbons caused to approach one another by means of the
divided screw worked by the ratchet wheel, trembler and shunt magnet,
substantially as and for the purposes herein described.
2. In electric arc lamps for projectors the use of a screw divided into two parts
one of which is free to move longitudinally in reference to the other whilst being
controlled to rotate with the other for the purpose of striking the arc substantially
as herein described.
3. The arrangement or combination and use of the parts of automatic arc
lamps used in projectors or search lights, substantially as and for the purpose
set forth.
T
11000
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicants.