CS207549B1 - Illuminating system of the projection apparatus - Google Patents

Description

(54) Lighting system for projection apparatus

The invention relates to a lighting system of a projection apparatus, in particular for reading or projection purposes for microfilm originals, comprising a projection bulb, an aspherical mirror and a single or double lens, refracting member with spherical or planar refracting surfaces.

For projectors that use a magnification factor of 12 x 50 x or higher to display film originals, it is necessary to ensure, in addition to a high-quality display with contrasting artwork and a resolution corresponding to the selected magnification factor, an image field illumination with sufficient intensity and uniformity. This problem has to be solved by using a lens with a sufficiently large relative aperture - depending on a magnification factor of 1: 5.6 to 1: 2.8, and especially a powerful lighting system that uses a suitable light source for the lens appropriately using light.

Such an illumination system is typically a light source and a two to three lens capacitor in which at least one aspherical surface is used. In addition to said members of the assembly, a spherical mirror is placed in front of the light source to increase the efficiency of the light source.

In order to protect the film medium from the heat radiation of the light source, an absorption or reflective (interference) part is included in the part between the light source and the subject window.

207 548 heat filter. For the same reason, the sludge mirror is also provided with an interference layer that suppresses the reflectivity of the long wave component of the light source.

This system is used in various types of lighting aids, but is particularly suitable for lighting systems where relatively short construction distances are required. For greater construction lengths, this ayatam, when chessing, results in the full light coverage of the entire aperture lens aperture to sharply increase the refractive power of the lenses extinguishing near the light source. This negatively affects the functional properties of these refracting members both structurally and technologically, leading to a compromise solution in which the aperture of the lens is not completely covered by light.

Some new types of lighting systems for reprographic devices solve this problem by replacing the function of refracting elements near the light source by the aafari mirror ρβνηβ associated with the light source. The reflecting surface of a mirror consists of many reflective facets. In the aperture mirrors, a substantial higher aperture can be selected in chessing good imaging properties than in refractive members, and a higher aperture of the lens can be illuminated. The aperture angle of these mirrors is generally greater than 90 °. This solution ae will reduce the number of members of the lighting system, but it is very demanding in terms of technology and especially its production of an apherical mirror.

Thus, there has been a need to design an illumination system that substantially reduces the disadvantages of known solutions. In a simple construction, it should ensure sufficient and uniform illumination of the entire displayed format.

This object is achieved by the object of the invention, which is a lighting system of a projection apparatus, in particular for reading or projection purposes for microfilm originals, consisting of a projection bulb, an apherical mirror and a single lens, possibly a double lens, refracting member with spherical or planar refracting surfaces.

The principle of the invention consists in that the aafarie mirror, located ae in the vicinity of the aviation source, has a conic curve and the parameters of the overall lighting system meet the following conditions

a) ainO 0,9 0.94 to 0.97, where O _z is the aperture angle of the aafaric mirror Z

b) L: f ₈ »15,0 to 30,0 L i é,« 4,5 to 9,0 where L is the total distance of the lighting system f and the focal length of the apherical mirror Z is the effective aperture of the apherical mirror Z

207 549

d) i _'C Ζΐ, ίί,

K 2u where f 'is the focal length of the refracting Sien C f _z is the focal length of the spherical mirror Z u is the diagonal of the backlit format.

The lighting system of the present invention is also based on the use of an aspherical mirror, but with a smooth, smooth and variable artifact curve. The aperturn angle of this mirror is greater than the aperture angles of the refracting members, but less than 90 °.

Such a mirror is technologically more advantageous than the above-mentioned types of aspherical mirrors and, in conjunction with other suitably selected refracting members, makes it possible to create an illumination system of considerable construction length while fully covering the aperture of the objective. The considerable length of the lighting system is advantageous from the point of view of the overall construction of the apparatus, since the considerable distance of the light source from the film medium and the associated possibility of optimum placement of the light source in the apparatus reduces the cooling system cooling system requirements.

Another advantage of the present lighting system is the possibility of two ways of positioning the light source with respect to the aspherical mirror:

In one case, the axis of the light source coincides with the optical axis 0 of the mirror Z, which is advantageous for bulbs with a cylindrical shape of the fiber body, the axis of the fiber body being coincident with the optical axis of the mirror.

2. For flat-fiber light sources, such as conventional types of projection halogen bulbs, it is preferable to position the light source so that the optical axis of the aspherical mirror extends through the center of the fiber body, perpendicular to the radiator spot. This filament position, in which the entire bulb is oriented perpendicularly to the optical axis of the aspherical mirror, can be realized by aperturning an aspherical mirror angle of 90 ° without compromising the integrity of the reflecting surface of the mirror. There is only a partial screening of the bulb bulb, but the efficiency of the reflective surface at the same aperture angle is higher than in a solution where an opening in the reflective surface of the mirror is required.

An exemplary embodiment of an illumination assembly according to the invention is shown schematically in the accompanying drawing, in which Fig. 1 is a sectional view of a complete illumination assembly and Fig. 2 shows an aspherical mirror with a circular opening.

As is apparent from FIG. 1, the illumination system comprises a low-voltage halogen lamp X and a filament V, an aspherical mirror Z having a cold reflective layer. A thermal filter I is placed in front of the refracting member C formed by the planconvex lens. The film window F is covered on both sides with cover glasses and K ₂ . The subject, placed in the Movie Screen F, is displayed by the O lens.

207 549

The light beams S emanating from the filament V of the halogen lamp X into the rear space are directed by an apherical mirror Z into the space of the film window F, in front of which a refracting Si, concentrating the travel of these light rays S into the pupil of the lens.

As can be seen from FIG. 2, a circular aperture 6 can be formed in the aspherical mirror Z, which is suitable for halogen bulbs X with a cylindrical fiber body V, the axis of which is on the optical axis o of the assembly. The arrangement of the other optical elements of the system is identical to the previous case.

Example 1 Aafan mirror Z - parabola y »38 x h ^ * 21.0 m _x β 279.0

heat filter T r ^ c-o 4,0 _χ 4.0 n _el - 1,518 r ₂ ^s mg · 2.0 brittle Sien C rt 16.4 dg «9.2 n _e2 «1.518 r ₄ = m @ + 6.0 Lenses K2, Kg * ο-c. d ₃ 5.0 n _e3 - 1.518 r _g <<7x0 d ₄ - 5.0 n _e4 - 1.518 »Γ » m ₄ ^and 12.6 lens 0 ^f 0 ^{x 15} ' ² Example 2 aspherical mirror Z - parabola y ² 38 x .v _x * 20.6 m / z 90.0 heat filter T «1 - 4.0 n _el «1.518 Tg ^{C <D} m ₂ «90.0 brittle Sien C Ie 26.0 dg «11.0 n _e2 - 1.518 ₄ - oo m ₃ * 22.5 cover glass Kp Kg r ₅ . oO d ₃ = 3.0 n _e3 - 1.518 r _g - o <o d ₄ · 3.0 n _e4 · 1,518 r _? »» m ₄ · 12.7 lens 0 * o ^{with W} » ¹ In both cases r ^ to r_ are radii curvature of individual stray surfaces, m až to m os axial thicknesses of the optical elements, V β m ^ to n> ₄ air optical gaps

the elements n _el to n _fl4 of the optical glass used and af _Q denotes the focal length of the lens 0.

The solved lighting system is suitable for run-off or projection devices where the wall or projected pattern is recorded on microfilm.

Claims (2)

BEFORE THE INVENTION 1. A projection apparatus illumination assembly, in particular for stecim or projection purposes for microfilm originals, comprising a projection lamp, an aspherical mirror and a single or two-lens, refracting element with spherical or planar refracting surfaces, characterized in that the aspheric mirror (Z), located near the light source (X), it has a conic curve and the parameters of the overall lighting system meet the following conditions: and) hall 0 of »0.94 to 0.97, where of is the aperture angle of the aspherical mirror Z (b) L: ^f z = 15.0 to 30.0 L: *of »4.5 to 9.0, where L is the total length of the lighting system AND is the focal length of an aspherical mirror *of is the effective diameter of the aspherical mirror C) sin i ain8 _c 2.5, where 8 2 is the aperture angle of the aspherical mirror Z _c is the aperture angle of the refracting member C d) 1,5 _c 1.5 f _z ^f >> 2u, where f 'is the focal length of the refracting member C c ⁱⁿ f is the focal length of the aspherical mirror Z zu is the diagonal of the backlit format. 2. Lighting system according to claim 1, having the following parameters: aspherical mirror Z - dish y »38 x ^v l * 21,0