SU635354A1 - Movie projector filament lamp - Google Patents

Description

one

The invention relates to the electrical industry and can be used in the production of projection incandescent lamps.

Projection incandescent lamps are known, consisting of a cylindrical bulb, inside of which there is a glowing body and an optical reflector system, which in turn contains a concave ellipsoidal reflector and a concave spherical reflector facing the ellipsoid with the formation of cup-like node 1.

The focus of the ellipsoidal reflector and the center of the spherical reflector coincide with each other and the center of symmetry of the filament body. The spherical reflector has an opening in the region of the main axis through which the reflected light rays are directed onto the optical system of the film projector.

Reflectors are mainly made from polished metal with good reflective properties.

The lamp has built-in elements in the flask for fastening the reflectors and the filament body and the base.

The closest to the technical essence is a film projection lamp, in which the bulb plays the role of an optical reflex system. In such a film projection lamp, the bulb has an ellipsoid-spherical shape with two cylindrical processes and a flat part of the wall on a sphere. The main axis of the ellipsoid and axis

the lines of the sphere form a single line, perpendicular to the axis of the lamp, at the point of intersection of which the focus of the ellipsoid is located, which coincides with the center of the sphere. This focus of the optical system is located

compact body heat.

The outer surface of the bulb has a mirror coating for the exception of the flat part of the sphere - the window through which the reflected light rays are directed to the optic system of the film projector 2.

The main disadvantage of such a lamp is the center of symmetry of the incandescent body in the focus of the optical system. This is not located on the body of the filament due to a large variation in the wall thickness of the bulb leads to the fact that if the difference in wall thickness exceeds a tolerable value of 1.096, the light reflection coefficient decreases, the losses due to spherical aberration deteriorate and the main parameter of the projection lamp deteriorates and becomes irreproducible - obtaining a uniform screen illumination,

created by the lamp - not less than 0.6.

The aim of the invention is to improve the uniformity of the light distribution of the lamp.

This goal is achieved by choosing the optimal position of the center of symmetry of the incandescent body on the Oitic axis of the lamp, namely the location of the center of symmetry of the incandescent body on the optical axis of the bulb at a point away from the focus of the optical system at a distance of 1.9-3% of the focal length.

In the drawing, an optical system of a film projection film and a graph of changes in light parameters: light and current (F) and light uniformity coefficient (K) as a function of the distance from the center of symmetry of the body to the optical system to the focus of the optical system, obtained experimentally.

The graph is obtained by processing the results of measuring the parameters of the lamps and locating the incandescent body relative to the focus of the optical system. Bulbs of lamps were made in various forms and from the droth with various geometrical sizes.

The role of the optical system in the lamp is played by a bulb consisting of the ellisoid part 1, the spherical part 2 and two ciliydric processes 3. A flat exit window 4 adjoins the spherical part. The entire surface of the bulb has a specular cover, with the exception of the window through which the reflected light rays on the optical system of the film projector. The main axis of the ellipsoid and the axis of the sphere form a single line - the optical axis 5, perpendicular to the lamp axis 6, at the intersection of which the focus of the ellipsoid is located, which coincides with the center of the sphere, which is the focus 7 of the optical system.

The following parameter values are set for lamps of this type:

Luminous flux value, lm nominal120

and 94

The value of the coefficient of uniformity of illumination

rated 0.65

limit of 0.6

However, as can be seen from the graph of the experimental check, when the center of symmetry of the jacal body is in the focus of the oitic system (point 0), located at a distance of 13.5 mm from the top of the ellipsoid surface, the luminous flux of the lamps exceeds the nominal value of 126 lm, and the uniformity coefficient illumination is at the limit of 0.6.

As the center of symmetry of the incandescent body moves from the focus toward the apex of the ellipsoid surface along the optical axis, the luminous flux of the lamps decreases, and the coefficient of uniformity of illumination increases.

When the center of symmetry of the incandescent body is shifted from the focus of the optical system to a distance equal to 1.9% of the focal length} 1i (point L), the illumination uniformity coefficient is at a nominal level of 0.65, and the light note rises to 123 lm, which exceeds memorial value.

When the center of symmetry of the incandescent body is shifted from the focus of the optical system to a distance equal to 3% of the focal length (point B), the luminous hue of the lamps is at the comminial level - 120 lm, and

the coefficient of uniformity of illumination rises to 0.675, which exceeds the nominal brightness.

Thus, the most optimal is the location of the center of symmetry

body glowing on the optical axis at a distance from the focus of the optical system within 1.9-3% of their focal length. When the center of symmetry of the incandescent body is displaced from the focus of the optical system to a distance of less than 1.9% and more than 3% of the focal length, one of the parameters continues to grow, and the second one becomes lower than the iomial distance and vice versa. Therefore, the displacement of the symmetry core of the jacal body beyond the specified limits is impractical.

Claims (2)

Invention Formula A projection incandescent lamp containing an optical-reflex system in the form of a mirror ellipsoidal-spherical bulb with two cylindrical processes, having a flat transparent exit window, and a compact incandescent body, located on the optical axis of the bulb, which is different in order to increase the uniformity of the light distribution, The center of symmetry of the incandescent body is located on the optical axis of the bulb at a point spaced from 1.9% to 3% of the focal length from the focus of the optical system. Sources of information taken into account during the examination 1. Patent of Great Britain, No. 904469, class-39 (2) B, 1961. 2. Swiss patent number 470081, cl. H 01 K 7/02, 1970. ten