Патент USA US2117737код для вставки
May 17, 1938. E. MAY 2,1 17,737 ILLUMINATING MEANS FOR PROJECTION APPARATUS Filed June '2, 1936 ii” 0'... o 1 I 1 INVENTOR Patented May 17, 1938 2,117,737 UNITED STATES PATENT OFFICE. 2,117,737 ILLUMINATING MEANS FOR PROJECTION APPARATUS Erwin May, Wetzlar, Germany, assignor to Ernst Leitz, G. m. b. IL, Wetzlar, Germany Application June 2, 1936, Serial No. 83,007 ‘ In Germany July 15, 1935 3 Claims. The object of this invention is to provide certain improvements in the illuminating means for pro jection apparatus embodying an arrangement in cluding the use of electric ?lament lamps where 5 by the image of the ?laments is formed in the plane of the picture instead of in the objective as is the case in prior'disclosures. In the art it is known that the image of the source of light in projection apparatus may be formed in the plane of the picture if arc lamps are used. But where ?lament lamps are used it has hitherto not been (01. 88-24) window 13 as will be understood. jecting objective and IS the screen. I4 is the .pro It indicates a rotating shutter if such is used. _ Rays from the lamp ?laments striking the ring formed mirror 8 will be re?ected back and form 5 offset images of the ?lament'threads in the plane of the ?lament as indicated by small dotted circles, the re?ected images of the ?lament threads being interposed between the ?lament threads themselves to provide an enlarged light 10 source in the plane of the ?lament. The rays from the light source or lighted area thus formed ?laments in the plane of the picture because the are in turn re?ected by the hollowmirror 6 in the ?laments do not form an evenly lighted surface, - plane of the ?lm or picture [2. Because of the l5 or area. Hence, in prior disclosures, the image fact that the. hollow mirror 6 has a more or less 15 , possible or practical to form the image of the of the ?lament is formed in the objective although ?nely grained, not smooth, re?ecting surface ‘I, ~ such an arrangement does not provide the best thejmages of the ?laments and of the displaced re?ected images of the ?laments are re?ected in possible illumination for projection purposes, it being. known, that maximum illumination is ob - 20 tained only if the image of the light is formed in the plane of the picture to be projected; the plane of the ?lm or picture [2 in a manner to completely blend and diffuse the separate ele- 20 ments of the source of light so that an even uni~ paratus for utilizing the full illuminating power of form illumination of the picture and ?lm is ob tained and the individual images of the several the light source from an electric ?lament lamp by illuminating elements disappear. The object of the invention is to provide an ap 25 forming the image thereof in the plane of the pic ture. Accordingly the invention is embodied in an arrangement or construction including an electric ?lament lamp the light of which is re?ected by a hollow mirror having a slightly grained surface so providing diffused or blurred re?ection of the ?la ment. ' In addition, the invention includes the use If desired, a condensing lens ii may be inter- 25 posed between the lamp and the ?lm, the lens having such a focal length and being so propor tioned and placed that it forms an image by re fraction of the two adjacent ?lament threads such as 3 and 4 into the plane of the ?lm in such 30 a manner that the re?ected images thereof lie at of a ring formed mirror for producing a laterally displaced re?ected image of the ?lament in its own plane whereby a diffused or spreading light 35 is obtained in the light source itself. A further object of the invention is to provide a condensing lens in front of the ?lament so arranged that the light rays of two adjacent ?laments are the edges of the ?lm i2 and thus illuminate the side portions of ‘the ?lm to compensate for the speci?cally directed toward the edges of .the ?eld prevent themjrom being noticed in the picture. 4c of the picture to compensate gforv a weakening or lessening of the light strength at the edges of the picture and whereby even uniform light is pro vided. ' The invention is illustrated diagrammatically ' in the accompanying drawing in which an elec tric lamp i is provided with a number of ?la ments. In the present instance and by way of an example there are four separate threads in the ?lament marked i, 3, ii and 5. ii is a hollow re ?ecting mirror having a slightly grained re?ect ing surface ii. a is a ring formed mirror the axis 9 of which is slightly offset from the optical axis it of the system. H is a condensing lens placed between the lamp i and the picture, slide or ?lm 55 it which is placed or exposed through a ?lm usual decrease or diminution in the illumination of the side portions which otherwise takes place 35 or occurs. The condensing lens may have a grained surface as at i8 whereby to cause a blurred re?ection of the two ?lament threads to However, even without such grained surface of 40 the condenser, the image of the two separately re ?ected ?laments practically disappears in the re ?ected light from the hollow mirror. With an arrangement or system as herein dis closed a re?ected offset image of the ?lament of 45 the lamp‘is formed in the plane of the ?lm and. the entire area of the ?eld of view of the pic ture is uniformly illuminated under ‘utilization of the full illuminating strength of the source of light. It is understood of course that the term 50 ' ?lm is used to indicate a picture or illustration to be projected. I claim:—- ‘ 1. An apparatus for illuminating a_?lm or pic ture to be projected upon a screen comprising an / 2 2,117,737 incandescent lamp having a plurality of sepa rated parallel ?lament threads in a single plane, so related with respect to the lane of the ?la ment and offset with respect to he optical axis of V a spherical re?ector to one side of the lamp be tween the latter and the screen having its focus so related with respect to the plane of the ?la the apparatus that it forms o?set images of the ?lament threads between the latter in the plane ment and offset with respect to the optical axis of the apparatus that it forms offset images of the ?lament threads between the latter in the side of the lamp having a?nely waved irregular re?ecting surface for re?ecting the illumination emanating from the ?lament and from there of the ?lament, a concave mirror on the opposite plane of the ?lament, a concave mirror on the - ?ected o?fset images of the ?lament threads upon 10 opposite side of the lamp having a ?nely waved irregular re?ecting surface for re?ecting the il lumination emanating from the ?lament and _ from the re?ected offset images of the ?lament threads upon the ?lm, the focus of the said re 16 ?ecting mirror being so related with respect to the ?lm that a diffused blended image of the ?la ment and of the re?ected images of the ?lament threads is formed in the plane of the ?lm. the ?lm, the focus of the said‘ re?ecting mirror being so related with respectto the ?lm that a diffused blended image of the ?lament and of the re?ected images of the ?lament threads is formed in'the plane of the ?lm, a condensing lens be tween the lamp and the ?lm a predetermined distance from the lamp whereby to cause the images of two adjacent ?lament threads in said lamp to be formed in the plane of the ?lm at the side portions thereof, one ?lament thread image at each side. 3. An apparatus according tocIaim 2 in which 2. An apparatus for illuminating a ?lm or pic ture to be projected upon a screen comprising an incandescent lamp having a plurality of separated parallel ?lament threads in a single plane, a the condensing lens has at least one ?nely waved spherical re?ector to one side of the lamp be irregular lens surface. tween the latter and the screen having its focus ERWIN MAY.