Improvements relating to the Production of Printing Surfaces by the Aid of Light.
Year: 1893

page_text: Date of Application, 21st Aug., 1893
Complete Specification Left, 21st May, 1894-Accepted, 23rd June, 1894
PROVISIONAL SPECIFICATION.
Improvements relating to the Production of Printing Surfaces by
the Aid of Light.
I, Dr. EUGEN ALBERT, of 55 Schwabinger Landstrasse, Munich, in the
Empire of Germany, do hereby declare the nature of this invention to be as
follows:-
In the Specification of Letters Patent No. 8043, dated the 23rd April 1892, for
Improvements relating to the Production of Printing Surfaces by the Aid of
Light, I have described how, in the copying of a half-tone negative on to sensitive
layers by means of ordinary tints or screens, the tones are divided into lines or
points in a similar manner as by photographic exposure owing to the solarization of
silver salts.
For this purpose the tint or screen is arranged at a certain distance from the
sensitive layer and the whole is caused during the copying to oscillate upon an
In order to obtain as many
axis parallel to the lines of the tint or screen.
gradations of tone as possible the simple tint or screen, after the first operation, is
turned in its plane through an angle of 90 degrees, the oscillating movement of
the tint or screen together with the sensitive layer upon the axis parallel to the
lines being repeated, as set forth in the aforesaid Specification. By this means
gradations of tone are produced which cross each other and are composed in a
peculiar manner.
Similar gradations of tone may also be obtained with a system of simple lines by
increasing the number of angles and also the angle which the two outer rays of
light form with each other.
When for instance seven gradations of tone are to be produced it is necessary to
let the light fall upon the sensitive layer in six different directions in succession.
Under these circumstances the sensitive layer will be formed with one series of
striæ which are illuminated most, and which I will designate in the present
example by the numeral 6. A second series of striæ will not be illuminated at all,
these being designated by the numeral 0. Between these extremes five other
series of striæ will be obtained which correspond to the several angles at which
the sensitive layer is exposed and which striæ may be designated by the
numerals 1, 2, 3, 4 and 5.
It is optional to copy the half-tone negative either before or after or simul-
taneously with the tint or screen.
In this method as well as in that described in the Specification of the aforesaid
Letters Patent No. 8043 the gradations of tone may be obtained by moving the
source of light instead of turning the tint or screen, or by using a number of
suitably arranged sources of light at the same time.
I prefer to employ electric lamps for this purpose. In this case the tint or
screen and sensitive layer remain altogether at rest, and the change of the angle
at which the rays of light fall upon the sensitive layer is effected solely by varying
the position of the sources of light.

page_text: COMPLETE SPECIFICATION.
Improvements relating to the Production of Printing Surfaces by
the Aid of Light.
I, Dr. EUGEN ALBERT, of 55 Schwabinger Landstrasse, Munich, in the
Empire of Germany, 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:-
In the Specification of Letters Patent No. 8043, dated the 23rd April 1892
for Improvements relating to the Production of Printing Surfaces by the Aid of
Light, I have described how, in the copying of a half-tone negative on to sensitive
layers by means of ordinary tints or screens, the tones are divided into lines or
points in a similar manner as by photographic exposure owing to the solarization
of silver salts.
For this purpose the tint or screen is arranged at a certain distance from the
sensitive layer and the whole is caused during the copying to oscillate upon an
axis parallel to the lines of the tint or screen. In order to obtain as many
gradations of tone as possible the simple tint or screen, after the first operation, is
turned in its plane through an angle of 90 degrees, the oscillating movement of
the tint or screen together with the sensitive layer upon the axis parallel to the
lines being repeated, as set forth in the aforesaid Specification. By this means
gradations of tone are produced which cross each other and are composed in a
peculiar manner.
Similar gradations of tone may also be obtained with a system of simple lines by
increasing the number of angles and also the angle which the two outer rays of
light form with each other.
When for instance seven gradations of tone are to be produced it is necessary as
shown in Figure 1 in the accompanying drawing to let the light fall upon the
sensitive layer in six different directions a, b, c, d, e, f in succession. s and to designate
the opaque and transparent lines of the tints or screens R in transverse section.
The striæ a f" of the sensitive layer MN are here illuminated most, and are
designated in the present example by the numeral 6, Figure 2. The striæ a" f¹
are not illuminated at all, and are designated by the numeral 0. Between these
extremes are striæ fl el and 6" all with the illumination 1, striæ e¹ and d¹
and with the illumination 2, striæ d' c and d c" with the illumination 3,
striæ c 6 and eld" with the illumination 4, and lastly striæ b'a' and "e" with
the illumination 5.
In Figure 2 the gradation of tone of these striæ is indicated by lines. The
half-tone negative may likewise be copied in the same manner as in the aforesaid
prior Patent No. 8043, either before or after or simultaneously with the tint or
.screen.
In this method as well as in that described in the Specification of the aforesaid
Letters Patent No. 8043 the gradations of tone may be obtained by moving the
source of light instead of turning the tint or screen or by using a number of
suitably arranged sources of light at the same time.
I prefer to employ electric lamps for this purpose.
In this case the tint or screen
and sensitive layer remain altogether at rest, and the change of the angle at which
the rays of light fall upon the sensitive layer is effected solely by varying the
position of the sources of light.
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. A method of producing printing surfaces by copying half-tone negatives

page_text: on to sensitive layers, characterized by the feature that, for the purpose of obtaining
a greater number of gradation of tone, the rays of light are caused to fall on the
sensitive layer at a greater number of angles during the previous or subsequent or
simultaneous copying of a screen or tint.
Second. A method of producing printing surfaces by copying half-tone negatives
on to sensitive layers by means of screens or tints, characterized by the feature
that the gradations of tone are obtained by moving the sources of light or by
simultaneously employing several sources of light.
Dated this 21st day of May 1894.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.