Improvements in Combined Ray Filters and Half Tone Gratings for use in Photo Mechanical Processes.
Year: 1899

page_text: Date of Application, 20th Dec., 1000
Complete Specification Left, 20th Sept., 1900-Accepted, 20th Dec., 1900
Date of Application, 20 DEC., 1999
Complete Specification Left, 20th Sept., 1900-Accepted, 20th Dec., 1900
PROVISIONAL SPECIFICATION.
Improvements in Combined Ray Filters and Half Tone Gratings for
use in Photo Mechanical Processes.
I, JOHN OWEN, of Merchantville (P.O. Box 87), in the County of Camden, and
State of New Jersey, United States of America, Photographer, do hereby declare
the nature of this invention to be as follows:-
My invention relates more particularly to what is known as the three color
process in which, as now carried out, three negatives are first taken of the
subject. From one of these the blue rays are shut out by a ray-filter of orange
glass placed just behind the lens; a second has the yellow rays shut out by a
violet ray-filter; the third, the red rays, by a green ray-filter. From these three
negatives three positives are next taken, and from the positives three grained, or
cross lined negatives from which copper plates are made in the usual manner.
It will thus be seen that, for the making of three copper plates nine distinct
photographic operations are necessary before you are ready to print on the copper.
Besides the waste of time and labor in this process it has the further disadvantage
that each re-photographing impairs the quality of the final result.
The object of my invention is to provide an improved construction whereby I
am enabled to make the last negative of each series directly from the subject and
thus make three photographic operations take the place of nine. My invention
consists of a ray-filter and a half tone grating combined in approximate optical
coincidence by either of the following methods:-
1. By flowing an ordinary engraved, or etched grating with collodion, gelatine,
varnish or other medium, holding in solution the colors in ordinary use as ray-
filters.
2. By making the grating by photography and staining the film used by
immersing it in the appropriate color prepared as dyes.
3. By selecting a sheet of stained glass of suitable color intensity to answer as
the ray-filter, and making the grating on it by the usual photographic process.
4. By preparing the ray-filters by the use of any suitable medium which is
unaffected by the after processes and then making the grating on them either
by photography or by other means in approved use.
5. By making the grating on a plate of glass and placing the colored medium
which is to act as ray-filter in optical contact therewith by any approved means,
either with or without a cover glass as may be thought best.
The use of my combined filter and grating does not call for any change in the
colors used.
The gratings used may be either cross-lined or granular.
2000
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C.,
Agents.

page_text: Improvements in Combined Ray Filters and Half Tone Gratings for
use in Photo Mechanical Processes.
I, JOHN OWEN, of Merchantville, County of Camden, and State of New Jersey,
in the United States of America, Photographer, 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 more particularly to what is known as the three color
process in which, as now carried out, three negatives are first taken of the
subject. From one of these the blue rays are shut out by a ray-filter of orange
glass placed just behind the lens; a second has the yellow rays shut out by a
violet ray-filter; the third, the red rays, by a green ray-filter. From these three
negatives three positives are next taken, and from the positives three grained,
or crosslined negatives from which copper plates are made in the usual manner.
It will thus be seen that, for the making of three copper plates, nine distinct
photographic operations are necessary before you are ready to print on the copper.
Besides the waste of time and labor in this process, it has the further disadvan-
tage that each re-photographing impairs the quality of the final result.
The object of my invention is to provide an improved construction whereby I
am enabled to make the last negative of each series directly from the subject
and thus make three photographic operations take the place of nine.
The attempt has often been made to do this with the ray filter placed near the
lens as in taking the first negative of the above series but inherent, and for the
most part, unavoidable, difficulties have prevented this way of working from
coming into noticeable use.
My invention consists of a ray filter and a half tone grating combined in
approximate optical coincidence by either of the following methods:-
1. By flowing an ordinary engraved, or etched grating with collodion, gelatine,
varnish or other medium, holding in solution the colors in ordinary use as ray-
filters.
2. By making the grating by photography and staining the film used by
immersing it in the appropriate color prepared as dyes.
3. By selecting a sheet of stained glass of suitable color intensity to answer as
the ray filter, and making the grating on it by the usual photographic process.
4. By preparing the ray filters by the use of any suitable medium which is
unaffected by the after processes and then making the grating on them either by
photography, or by other means in approved use.
5. By making the grating on a plate of glass and placing the colored medium
which is to act as ray filter in. optical contact therewith by any approved means,
either with or without a cover glass as may be thought best.
The accompanying drawings are diagrams which illustrate the relation of the
parts in the different modifications of my device above enumerated, and the five
different figures correspond with the different modifications as numbered above.
In these figures A represents a sheet of clear glass; B a sheet of clear glass ruled
as a grating, C a sheet of stained glass which acts as a ray filter, a, a sheet of
cover glass, v, a sheet of colored collodion or its equivalent, P a photographically
formed grating, S a similar grating stained to act as a ray filter. R a colored
ray filter of any suitable medium.
The use of my combined filter and grating does not call for any change in the
colors used.
The gratings used may be either cross-line or granular. I prefer to use a

page_text: granular screen in making the negatives for the first two plates that are printed,
and a cross-line grating for the last one.
For reasons which will readily occur to persons skilled in the art, I prefer to
place the combined ray filter and grating very close to the dry plate for the
negative, and I therefore prefer to use a grating which is designed to be placed in
close contact with the photographic plate, as, for example, one of the "vignetted
screens" described by E. Deville on page 45 of Vol. 1 of the "Practical Process
Worker and Photo-Mechanical Printer (a technical journal published in New
York in the United States of America).
But I do not limit myself to the precise screen or grating therein described, as
any grating which can be used in the same way will answer equally well the
purposes of my invention.
Aside from placing them as above specified, as near the photographic plate as
the type of grating used will permit, my combined filters and gratings call for no
different manipulation than is required for the same filters and gratings when
uncombined.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is: -
1. A half tone grating having a colored ray filter in approximate coincidence
with its working surface; substantially as and for the purpose set forth.
2. A combined half tone grating and colored ray filter which have their
approximation to each other carried to a point at which they cease to reflect light
to each other.
3. A half tone grating and a colored ray filter in optical contact therewith,
in combination with each other and with an inflexible transparent support.
4. The combination of a translucent sheet, a half tone grating which forms an
integral part of the sheet, and a colored ray filter in optical contact with the half
tone grating: all as set forth.
5. The combination of a half tone grating which has been photographically
formed in the substance of a film with a staining for the film; substantially as and
for the purpose set forth.
Dated this 20th day of September 1900.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C.,
Agents.