SU49345A1 - Sound film projector - Google Patents

Description

In order to obtain high-aperture lighting systems in projection apparatuses, it is necessary to strive for shortening the distance from the light of the body to the projection window. In addition to increasing the aperture ratio, shortening this distance increases the uniformity of illumination and reduces the required accuracy of the light source setting, all other conditions being equal.

To achieve this goal, the conventional three-lens condenser in the proposed sound film is designed in such a way that the obturator is placed between the first condenser lenses, as a result of which a light beam from a mechanical slit located above the condenser passes between the second condenser lenses.

For a narrow film projector, for which the described invention is intended, it is also important to maintain the required limited distance between the projection window and the reading position of the phonogram required by the standard to preserve the synchronicity of sound and image, which does not allow the optical tube of the sound unit to be sufficient lengths to achieve a sufficient system magnification, since small magnifications in sound optics, especially in narrow-film projectors, cause undesirable oteryusveta in mechanical slischkom narrow slots x.

The proposed optics system makes it possible to increase the length of the tube without increasing the distance from the personnel window to the point where the phonogram is read, and since the light beam from the mechanical slot in this place has very little width, there is no need to significantly increase the distance between the condenser lenses that would lead to an undesirable increase in their diameter.

With this arrangement, the mechanical slit is higher and the micro-lens is below the lighting condenser.

In FIG. 1 is a longitudinal axial section of the sound film projector; and FIG. 2 shows a section along AB of FIG. one.

A film wound on a reel is placed on the upper bracket of the apparatus /, which simultaneously serves as a rewinder of the films watched. Through the input rollers, the film enters the feed drum 2, from which the loop goes into the projection frame 5 through which it is transported by a conventional eccentric grab mechanism. After the projection frame, the film is accepted by the intermediate drum 4, from which the free loop enters the sleek sound drum 5 equipped with a flywheel and is pressed against the drum by a pressure roller 6. Directly on this drum, the phonogram is read.

From the drum 5, the film t is nets by the receiving drum 7, after which through the shock-absorbing roller 8 it goes to the receiving bobyma rotated by a conventional friction device.

A projection lamp 9 is illuminated using a condenser 10 film in a projection window, the image of which is thrown onto the screen by a projection lens //.

The light beam between the lenses is interrupted by the obturator 12.

For the illumination of a phonogram, the same lamp is used. For this purpose, a mirror 13 is installed, which rejects a beam of light from the lamp onto the condenser 14 of sound optics.

Directly beneath the latter is a mechanical slit 15, the image of which with the help of a micro-lens 16 is dropped onto the phonogram of a film moving along a smooth drum 5.

A system of two prisms 17 is attached to the beam of modulated light and directed to the photocell, which shifts the beam of light beyond the edge of the film and directs it to the photocell 18.

The transport mechanism is the usual grab. The gear drums are driven into rotation by conventional gear and worm gears.

Other parts, clamping slide, lubrication system, installation of the device on the screen, drive dvigagel, etc. - conventional systems.

In the described invention, a well-known filter is applied, kinematically directly connected with the projector mechanism and consisting of a smooth drum 5 and a flywheel 19 sitting on its axis with the following changes and additions.

As is known, the quality of the operation of such a filter is measured by the ratio of the detonation frequency to the self-resonance frequency of an oscillating system.

filter. Thus, the longer the filter oscillation period, the better it will smooth out the detonation.

To increase the filter oscillation period, either the flywheel inertia must be increased or the contour elasticity reduced.

With the given dimensions and weight, it is not possible to increase the flywheel; it is only possible to reduce the elasticity, which in this case is the elasticity of the film section from the smooth drum to the receiving toothed drum.

To reduce this elasticity, the following method has been applied in this system.

Resilience will decrease if film tension decreases. To facilitate the tension of the film, a special uniformly rotating intermediate drum 4 was used, the purpose of which is to take a pulsating film out of the projection frame and feed it with a free loop to a smooth sound drum.

It is not possible to directly feed the film onto the drum, since the sound quality of the film will be affected by the oscillation of the film from its abrupt movement in the projection frame; The use of conventional tools is disadvantageous, since they increase the force required for pulling the film.

To reduce the load, the axis of the smooth sound drum rotates on ball bearings.

In addition to the detonations caused by the uneven rotation of the transporting film through the drum sound unit, the teeth of the transporting drum have a large effect on the sound distortion.

This is caused by the fact that, in conventional systems, the tooth of the drum, at the entrance to the perforation hole, produces blows to the film, which are heard as characteristic rales.

This phenomenon is especially dangerous when applying a narrow film that has only one perforation point for each frame of the film.

To eliminate this phenomenon in the proposed system, the 1st drum 7 is not pulling the tape, but only delaying it. The film is stretched from the appack to the author's certificate of V.M. No. 49845 Kalmanson

Type of. Pechgchny Labor. Zak 493-400