IMPROVEMENTS IN REFLECTORS
Year: 1881

page_text: LETTERS PATENT to Herbert John Haddan, of the Firm of Herbert and
Company, Solicitors of Patents, of 67, Strand, in the City of Westminster,
Civil Engineer, for an Invention of "IMPROVEMENTS IN REFLECTORS."
A. communication from abroad by Charles F. Brush, of Cleveland, State
of Ohio. United States of America.
PROVISIONAL SPECIFICATION left by the said Herbert John Haddan at the
Office of the Commissioners of Patents on the 28th April 1881.
HERBERT JOHN HADDAN, of the Firm of Herbert and Company, Solicitors of
Patents, of 67, Strand, in the City of Westminster, Civil Engineer. "IMPROVEMENTS
IN REFLECTORS." A communication from abroad by Charles F. Brush, of
Cleveland, State of Ohio, United States of America.
The Invention consists of a reflector having a concave face, such as would be
formed by bending a flat sheet, so that it would have in cross section the form of a
parabola; also in combination with a. reflector having a concave face, such as
would be formed by curving a flat sheet in one direction only, of one or more cut-
off plates suitably shaped to accord with the curve of said reflector; also in the
combination with a concave reflector of a cut-off tube having a non reflecting
inner surface, said tube located in such proximity to the light or flame as to
intercept and cut off the direct rays of light. The Invention relates to reflectors
for electric and other lights, and has for its object the suppression of the direct or
unreflected light issuing from the luminous source without interferring materially
with the reflected rays. The Invention is performed by shaping the reflector so
that it combines the characteristics of a cylinder and parabola, and the various
parts may be made of metal, plated or otherwise formed."

page_text: .
Figure 6, a front view of the said modified device.
Figure 7, a view of my device in side elevation, showing the position and relation
of the cut-off plates.
Figure 8, a front view of the device shown in Figure 7.
Figure 9, a combined section and plan view of the same; showing the shape of
the cut-off plates.
Figure 10 is a cross-section through the axis of an ordinary parabolic reflector
provided with a device for carrying out my Invention.
Figure 11 shows a front view of the same.
Figure 12 shows a shallow spherical reflector provided with a device for accom-
plishing the desired result.
Figures 13 and 14 show modified forms of construction.
As sufficiently indicated in the Drawings my reflector combines the characteristics
of a cylinder and parabola, such as could be produced by curving a flat sheet of
metal to the form of a parabola, as shown in Figures 1 and 2. When the light is
placed in the focus of this parabola the reflector will be in the form substantially.
of a horizontal sheet extending through an arc of one hundred and eighty degrees,
more or less, according to the adjustment or peculiar construction of the reflector.
This is indicated in Figures 2 and 3 of the Drawings, which show the direction of
the light-rays.
'
I have designed this reflector for use more particularly with the electric light,
although I do not limit its use thus narrowly; I have therefore shown in the
Drawings the usual carbons and their voltaic are as the luminous agent.
In the form of reflector shown in Figs. 1, 2, and 3 the illuminating carbons will
cast their shadow, and where this would be undesirable the modified form illustrated
in Figures 4, 5, and 6 may be adopted. This modification consists merely in
constructing the back of the reflector in an angular fashion, as shown in Figures 4,
5, & 6, instead of straight, as shown in Figures 1 and 3.
Cut-off plates A are provided. They are held by any suitable. attachments or
supports in substantially the position and relation indicated in the Drawings.
In Figure 2, which shows these cut-off plates omitted, it will be seen how the
direct rays of light diverge in front of the reflectors, and Figure 7 illustrates how
these rays are cut off by the provision of the cut-off plates A. These plates in
order to intercept no more rays than desirable should have a form substantially as
shown in plan view in Figure 9, but this form will vary with different curves
given the reflector to accord with reflectors of varying depths.
The shape of the edges a should conform suitably with the definite parabolic

page_text: curve imparted to the reflecting surface, as these edges of the plates A intercept
the direct lateral rays.
The front edge a may be made circular in form, and this will intercept the
direct rays that would escape beyond the upper and lower front edges of the
reflector, which are straight.
If it is desired to intercept the light-rays in one direction only then a single cut-
off plate, say the upper one, will be sufficient to arrest the rays in that direction.
B, Figures 10 and 11, is a parabolic reflector provided with openings in the
usual manner, through which the carbons b, b, of an electric lamp pass, uniting at
or near the focus e of the reflector.
C is a tube of thin metal, open at both ends, and having its axis coincident
with the axis of the reflector. This tube is placed sufficiently near the luminous
point to obstruct the cone of light d, f, which would otherwise issue unreflected
from the parabola, but not sufficiently near to intercept rays of light which would
fall within the reflector. The tube C evidently does not interfere with the reflected
light, since the latter may all pass through and outside of it. The unreflected
light issuing from the tube is so slightly divergent as to be unobjectionable.
The tube C may be supported in position by any suitable means, one method
being shown in the Figures. In practice I prefer to attach the tube to guides,
through which the carbons b, b, pass, so that the relative position of the tube and
luminous centre may remain constant while the position of the light is changed
backward or forward to make the reflected beam slightly divergent or parallel, as
may be required.
Figure 12 shows my device adapted to a shallow reflector. Here the tube C
necessarily extends slightly back of the carbons, and is provided with suitable
openings, through which the carbons pass, as shown.
The tube C should not have a reflecting surface inside, because if reflecting the
cone of light entering it will after several reflections emerge, as the same cone
diminished in intensity however by the reflections it has undergone.
Figure 13 shows a disk c substituted for the tube C, Figure 1.
Figure 14 shows a disk and tube i substituted for the tube C, Figure 3. This
disk i while it may be employed as an inferior substitute for the tube I do not
consider to be an equivalent thereof. I have merely referred to the disk in this
Specification by way of explanation, but as it is my intention hereafter to make
separate application for Letters Patent upon said disk I do not intend by anything
disclosed in this Specification to waive any right of hereafter applying for and
securing a Patent upon the disk c referred to.
What I claim is,-
First. A reflector having a concave face, such as would have been formed by
bending a flat sheet, substantially as shown, so that it would have in cross section
the form of a parabola.
Second. The combination with a reflector having a concave face, such as would
be formed by curving a flat sheet in one direction only, of one or more cut off
plates A suitably shaped to accord with the curve of said reflector, substantially as
and for the purpose shown.
Third. The combination with a concave reflector of a cut-off tube having a
non reflecting inner surface, said tube located in such proximity to the light or
flame as to intercept and cut off the direct rays of light, substantially as shown and
described,
In witness whereof, I, the said Herbert John Haddan, have hereunto set my
band and seal this Twenty fifth day of Outcher AD 1001
H. J. HADDAN. (L.S.)