The Washington herald., 1915-07-25

By Rival
of Edison

ELICKERLEss motion pictures are
promised through the invention Of
DR.. Dinshah P. Ghadiali. The device
is known as the "Shutterless, Flicker
less, Continuous Motion Picture Projec-
tor" Briefly, DR.. Dinshah's system en-
braces a double window. one of which
is known as the jumping window" and
a prism arrangement so that continu-
Gus flow Of light on the screen is OBJ
tanned.
The flicker in a motion picture IL
caused by the shutting of Of the light
forty-eight times a second. Naturally.
the light is turned on and off too rapid
ly to be distinctly observed. but the
flicker effect nevertheless remains and
has engaged the attention Of motion pic
ture experts for years. All inventors. in
GLIDING the premier Of all, Thomas Edi-
son. have endeavored to end the flicker.
but 1t was left for DR.. Dinshah to per-
feet machine which it is claimed does
away absolutely with the flicker and in
sures continuous. even run Of pic
lures.
Most people have only g vague idea Of
the mechanism used in reproducing a
motion picture. The standard film con-
tains sixteen pictures to the foot. each
picture being three-quarters of an inch
in height. The speed used in running
the film through the motion-head of the
protector is about a foot a second. This
means that the delicate celluloid film is
moved past the optical system the height
of one picture Tor three-quarters of an
inch) sixteen times during each second
by mechanism which engages the small
perforations running alongside the film.
quickly rotating shutter cuts off the
beam Of light from the lamp-house, which
Is in the rear of the machine, while each
successive picture is being pulled into its
proper position. In the better types Of
machines now used. the light is cut of
and put on three times per picture, or
forty-eight times per second. In other
words. the screen is in absolute darkness
a certain portion Of each second and Is
illuminated only a fraction of the sec
ond. This is the cause of the flicker.
In the Dinshah machine the arc light
and the condensers are of the familiar
type. The film is moved smoothly and
continuously at any predetermined speed
by small electric motor between two
windows or film gates. The first one is
stationary and has an aperture the width
Of one picture and the height Of two,
and is aligned with the center of the
optical system. The second window Is
movable and has an aperture the exact
size Of one picture. This second or
Jumping Window" is so arranged as to
the fixed window, until the moving win
dow has travelled the height of one pic
ture, when this window jumps up to fol-
low the next picture which has mean
while come within the aperture of the
fixed window.
In this way. the film Is illuminated
constantly through the fixed window or
the height Of two pictures, but only one
picture is actually shown through the
lenses at one time, due to the peculiar
action Of the jumping window.
II the light be projected on the screen
directly, the pictures would simply ap-
pear to travel upward on the screen as
they went downward in front of the
condensers. To rectify this, Dr. Dinshah
used view-correcting prism in a very
ingenious manner.
When the picture and the jumping
window have reached the center line of
the optical system on their trip down.
ward, the cubic prism has one of its
sides at right angles to the beam OF
light, and the projection appears in its
proper position on the screen at that
instant. as the rays of light pass through
the prism in straight line. As the
jumping window and the picture move
further downward, the top Of the prism
moves toward the condensers. with the
result that the now refracted beam of
light still strikes the objective properly
and the picture appears constantly IN
the same focal plane.
At whatever angle the beam Of light
enters the prism. 1t always emerges in q
line parallel to that Of its incidence and
Just enough higher or lower to keep the
projected picture in the center Of the OBJ
jective through the absolute synchroni-
zation of the jumping window with the
picture and the prism.
The movement Of the prism is of an
oscillatory character, and in accordance
with the necessary synchronization to the
window, which, after following a picture
its entire height, jumps upward, carrying
with 1t the prism to its normal position.
During this period the light is never cut
off from the screen