Improvements in Moving Pieture or Consecutive View Apparatus,
Year: 1899

page_text: Date of Application, 29th Mar., 1899-Accepted, 13th May, 1899
COMPLETE SPECIFICATION.
Improvements in Moving Pieture or Consecutive View Apparatus,
I, WILLIAM KENNEDY LAURIE DICKSON, of 18 and 19, Great Windmill Street,
near Piccadilly Circus, London, Gentleman, do hereby declare the nature of this
invention and in what manner the same is to be performed to be particularly
described and as ascertained in and by the following statement:-
My invention relates to moving picture or consecutive view apparatus, and con-
sists in the use, in connection with mechanism for feeding a film, picture strip,
or other view carrier, through a field of view, illumination, or exposure, of a
prisin of variable angle located in the optical axis and mechanism for varying
the angle of said prism in such manner that although the film or other view carrier
is moving constantly through the field of the apparatus, it is held optically
stationary, at intervals, with respect to the lens or point of view. The effect of an
intermittently moving view carrier, which is stationary during the periods of
exposure, is thus obtained, without the disadvantages incident to intermittent or
irregular movement of the view carrier, such as vibration of the view carrier and
apparatus, producing indistinctness of the picture, and, if the view carrier be a
film or picture strip, strain upon and wear of such strip. And my invention
further consists in the novel combination, construction, and arrangement of the
parts of the apparatus.
The objects of my invention are, to improve and simplify that type of consecu-
tive view apparatus in which the film or view carrier moves continuously, and
in which means are employed for causing the rays of light to move in accordance
with the movement of the view carrier, during the intervals of exposure or
illumination, so that during such intervals the film or view carrier, although mov-
ing continuously, is optically stationary with reference to the lens or the point
of view; and also to make the apparatus as simple and compact as possible, not
liable to derangement, and easily operated.
These objects are attained in the invention herein described and illustrated in
the drawings which accompany and form a part of this specification, in which
the same reference numerals indicate the saine or corresponding parts, and in
which:-
Figure 1 is a side elevation of the mechanism of the apparatus, the enclosing
case being sectioned; and Figure 2 is a detail view, looking from the right of
Figure 1, of the prism of variable angle, the cam, and the connections by which
the sections of said prism are vibrated as the cam revolves.
The apparatus shown in the drawings is adapted for the use of a long flexible
film as a view carrier. But other types of view carriers may be used instead.
The apparatus shown is a projecting apparatus (the lantern being omitted) but
the same mechanism may be used in a camera, or in a direct vision reproducing
apparatus.
In the drawing, 1 indicates a supply reel, and 2 a winding up reel. 3 is a
1chaft 1 is a fooding roller driven from the shaft 3 by a friction wheel 5
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page_text: and friction disk 6, the former being radially movable with respect to the latter,
so that the rate at which the film is ted may be varied. 7 is an idler roller which
holds the film against the feeding roller 4. The winding up reel 3 is driven by
abelt 8 deriving its motion from a shaft 9 driven by gearing from the driving
shaft. 10 is a guide roller for the film, and 11 and 12 are guide frames between
which the film passes.
13 is the objective lens of the projecting apparatus. In rear of this lens is a
prism of variable angle, 14, suitably supported, and consisting of two parts, 1+
and 14, each of which is a prism. The two parts 14 and 14" are mounted to
rotate about the optical axis, and are provided with downwardly extending
fingers 15, the ends of which enter cam grooves in a cam 16 mounted on the main
(triving shaft 3. When this shaft rotates, therefore, the prisms 14' and 14" rotate
back and forth, in opposite directions, through arcs of circles, the effect of this
being to alternately increase and decrease the angle between their adjacent surfaces.
The angle" if a prism of this character, composed of two separate parts, the outer
surfaces of which are parallel, is the angle between the inner surfaces of the two
parts of the prism; and the effect produced by such a prism is the same as though
the prism were composed of but one part, the angle between the sides of which
is the same as the angle between the adjacent surfaces of the parts of the composite
prism.
00
The effect of the variation in angle of the prism 14, produced by the relative
motion of the parts 14 and 14", is to deflect the rays of light in such manner
as to compensate for the movement or the film during the intervals of exposure,
holding the pictures thereon optically stationary with reference to the lens 1:3
during such intervals of exposure, notwithstanding the movement of the film.
17 is the shutter disk upon the driving shaft 3. 18 is a condensing lens. 19 js
a shifting lever by which the radial position of the friction wheel 5, with reference
to the friction disk 6, may be varied, for the purpose of compensating for slipping
or shrinkage of the film.
In the operation of the apparatus, as the shaft 3 rotates, the film is fed downward
from the reel 1 and wound upon the reel 2, the belt 8 slipping to compensate for
the gradually increasing diameter of the winding up reel. As the shaft 3 rotates
the prisms 14 and 14" vibrate through arcs of circles, in opposite directions, thus
varying the angle of prism 14, and deflecting the optical axis and the rays of light
upward and downward alternately. During the upward movement of the optical
axis the light is shut off from the lens 13; but during the downward moveinent,
which is in the direction of motion of, and at the same speed as, the movement
of the film, the shutter is open.
I do not limit myself to the details of construction and arrangement of the
apparatus illustrated, but believe my invention to cover, broadly, the use of a
prism of variable angle for holding a moving view carrier optically stationary
with reference to a lens or point of view at intervals.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. In a consecutive view apparatus, the combination, with means for feeding
a view carrier through the field of the apparatus, of a prism of variable angle,
and means for varying the angle of said prism in synchronism with the passage of
sections of the view carrier through the field of view, whereby sections of said
view carrier may be held optically stationary with reference to a fixed point
during their passage through the field of the apparatus, substantially as described.
2. In a consecutive view apparatus, the combination, with film or strip feeding
mechanism adapted to feed a flexible film or picture strip through the field of the
apparatus, of a prism of variable angle, and means for varying the angle of said
prism in synchronism with the passage of sections of the film or picture strip
through the field of the apparatus, whereby sections of the film or strip may be