SU1486977A1 - Method and apparatus for motion-picture projection - Google Patents

Description

The invention relates to an optical instrument and improves the quality of film projection by increasing the luminous flux and improving the uniformity of illumination of the frame. In the intermittent movement of film 3 in the movie channel 5

using a jump drum 6 in the projection section, frames are illuminated by the lighting system and the still frame is projected in frame window 4 by lens 8. During a frame change, parts of the previous and subsequent frames are illuminated by a light beam moving in the direction of film movement by a deflecting mirror 15 connected kinematically through a pusher 17 and cam 18 with intermittent motion mechanism. At the time of the projection of the moving parts of the frame, the main channel is blocked by the blade of the obturator 7 and their projection is performed by the lens 9 and the compensator mirror 13, kinematically connected through the pusher 12 and the cam 14 to the intermittent motion mechanism. The mirrors 13 and 15 are returned to the initial position with the help of opposing springs 11 and 16. 2 s. item f-ly, 1 ill.

<p

5C, „, 1486977

one

1486977

The invention relates to optical instrumentation, namely to the film projection technique.

The purpose of the invention is to improve the quality of the projection by increasing the luminous flux and improving the uniformity of illumination of the projected frame.

The drawing shows a device for implementing the method of film projection.

The device contains an illumination system with a source 1 of light, a condenser 2, which provides uniform illumination of only one frame of intermittently moved film 3 in the frame window 4 of the film channel 5 with the help of a jump drum 6 of the intermittent motion mechanism as well as a one-blade mirror obturator. 7, the main 8 and the additional 9 lenses, a compensator in the form of a mirror 10, one edge of which interacts with the spring 11 and the other with the pusher 12, causing the compensating mirror 10 to rotate relative to the axis of rotation 13 using a cam 14 kinematically connected with the mechanism 6 intermittent motion of the film and the obturator 7, respectively. Spring 11 leads mirror 10 to its original position.

The device also contains a deflecting mirror 15 installed in front of the personnel window 4 of the film channel 5 at an angle to the optical axis, interacting with the return spring 16 by one edge and the pusher 17 in contact with the cam 18 of the intermittent motion mechanism and ensuring the rotation of the mirror 15 around the axis nineteen.

In the initial position, the mirror 15 is set at an angle of 45 ° to the optical axis, with the working angle of rotation φ of the mirror 15, which allows the light beam to move in the direction of motion of the film (film 3) by the pitch of the projected (fixed and then changing) frame, i.e. on height / g ™, is determined from the ratio

Yko

F = 2gs1 ^ -,

where /. - the distance along the optical axis from the axis of rotation of the mirror 15 to the frame window 4 of the film channel 5.

Frame window 4 is made the size of the height (along the direction of movement of the film) / g ,,., Exceeding more than in. 2 times the height of the projected frame

/ ϊ »ι =: 2 / Ζκ <>,

where b * is the height of the interframe strip.

For only one projected frame to be illuminated, it is necessary that the shape of the light beam in the plane of the frame window match the shape of the luminous body of the light source 1, and the magnification β of the lighting system to illuminate only one frame must be equal to

where Lko is the height of the projected frame;

- the height of the cross section of the luminous body

light source.

The device works as follows.

The film 3 is intermittently advanced in the film channel 5 with a projection frequency adopted 24 frames per second. Moreover, 3/4 of the period T is the projection of a still frame using the main lens 8 on the screen (not shown). Then 1/4 of the period T, when the frame is changed, the main channel is blocked by the obturator 7, the moving frame is projected using an auxiliary lens 9, a mirror 10, the motion compensator of the film 3 and is aligned with the image of the projected still frame.

During the projection of a moving (interchangeable) frame using a deflecting mirror 15, kinematically connected with an intermittent motion mechanism, synchronous movements of the light beam occur in accordance with the movement of the projected frame in the film channel 5. And in this case, the previous and subsequent frames are not covered with the projected main. At the time of the projection of the still frame deflecting mirror 15 returns to its original state and still, since it is kinematically connected with the mechanism of intermittent movement through the pusher 17 and the cam 18.

The formation of a light spot in the plane of the personnel window 4 of the film channel 5 to illuminate one frame is provided by reducing the increase in the illumination system of the film projector. In order to increase the uniformity of illumination of a frame, the borders of the light spot should usually be in the form of a circle described around the frame (rectangle). Since the light spot "monitors" the frame being moved, the uniformity of illumination over the area of the frame does not change.

Claims (2)

Claim 1. A way of film projection, which consists in projecting a still image with a light beam onto a screen from a discontinuous movable film in a film channel, then, when changing a frame, parts of the previous and subsequent frames are projected onto the screen, characterized in that increase the luminous flux and improve the uniformity of illumination of the projected frame; when changing the frame of the previous one to the next one, the light beam is moved 1486977 five in the plane of the frame window in the direction of the film, while the cross-section of the light beam in the plane of the frame window is equal to the size of one frame. 2. A device for film projection containing a lighting system with a light source installed along the optical axis, a film channel with a frame window, a single-blade mirror obturator, a main lens, as well as an intermittent ^10- motion mechanism, an additional lens and a compensator in the form of a mirror that can be rotated under angle to the optical axis of the additional lens and kinematically associated with the mechanism of intermittent motion, characterized in that, in order to improve the quality, it is equipped with m at an angle to the optical axis with an additional mirror installed in front of the film channel with the possibility of rotation and kinematically coupling 20 associated with the mechanism of intermittent motion, and the size of the personnel window along the direction of film movement exceeds the size of two frames, while the working angle of rotation φ of the additional mirror is determined from the relation , / to <р = arc {§2 ~ where / k. ”is a value equal to half the size of the personnel window along the direction of the filter; B is the distance along the optical axis from the additional mirror to the frame window, and the increase in β of the lighting system is determined from the ratio where K _and - the height of the cross section of the body of the channel of the light source.