Patent GB-1012679-A (GB)
Title: Stereo viewing projection apparatus
IPC: G02B27/22
Filed: 1963-01-01
Abstract: 1, 012, 679. Stereoscopic projection apparatus. GOODYEAR AIRCRAFT CORPORATION. Jan 1, 1963 [June 7, 1962], No. 40/63. Heading G2J [Also in Division F2] Stereoscopic projection apparatus in which projected stereo images are superimposed comprises a composite optical screen 32 formed by a laminate of semi-specular material 38 and a Fresnel lens 36, and a pair of inclined projectors 12, 14, which receive and project stereo pair films. The Fresnel lens and material 38 are placed face-toface between rigid transparent supports 40, 42, material 38 being a transparent film base 44 treated to provide one patterned surface of minute geometrical optical lens elements 46 at about one million elements per square inch. These elements restrict the viewing angle and so provide a directional projection screen, the Fresnel lens acting as a field lens. The right and left eye stereo images are thus directed exclusively to the right and left eyes respectively at viewer 34. The viewing angle in the horizontal direction is ten degrees and in the vertical direction is forty degrees. In an embodiment, an automatic focusing linkage enables the superposed image size relationship to be controlled while the projected images may be shifted horizontally and vertically by means of a system of tilting mirrors. Light from source 56 is reflected into two paths by inclined mirrors 58, 60. The separate beams then pass through condensers 62 and 64 and are reflected downwardly by mirrors 66, 68 through condensers 82, 84 and film 92 on to inclined mirrors 94, 96 and 98, 100 which direct the beams upwardly to mirrors 162, 164 which send the light through the left and right optical lens systems. Light leaving the lens systems is then reflected by mirrors 186, 200 and 188 on to screen 32 a. Control of image position. Mirrors 94, 96 are mounted at 38 degrees and 45 degrees respectively to the horizontal on plate 102 pivoted at 104 on guide plate 106, biasing spring 108 engaging pivot 104 and holding cam rod 112 on plate 102 in engagement with frame 54. Plate 106 has a threepoint suspension with frame 54 where ears 114, 116 enter slots 115, 117 and ear 118 enters horizontal slot 119 so that plate 106 may move horizontally also and pivot about a vertical axis through ears 114, 116. Rotation of eccentric cam 120 through shaft 122 pushes plate 106 horizontally against spring 123 so that mirrors 94, 96 are tilted by the interaction of rod 112 on frame 54. The right mirrors 98, 100 are similarly mounted, the ear 146 also entering slot 119. Right and left mirrors are pivoted about their vertical axes by rotation of shaft 158 and hence of the set-screw 154 to move ears 118, 146 in their slot against spring 160. A further left mirror 162 above mirror 96 is pivoted about horizontal axis 166 against spring 168 by means of screw 170 in control panel 124; right mirror 164 is similarly controlled. Control of lens systems. The left optical system has slidably mounted on rod 182, a first lens 172, a field lens 174, and a second lens 176 with an adjustable diaphragm controlled form panel 124, the right system is simularly mounted. The left optical system has an automatic lens focusing linkage 202 close horizontal motion is controlled by rotatable threaded rod 210. Bell-crank 252 has slotted arms 254 and 258 and is pivoted at pin 262 offset from the plane of lens 172 by a distance "x" and lying in a plane spaced from the optical axis by a distance of "f 6 ", the focal length of lense 172. Horizontal link 264 rigidly connects pin 262 to first lens housing 172a. Second pivot pin 266 is secured to lens housing 176a and is restricted by slot 204 in form 54. Drive washer 268 is connected to lens housing 174a by link 274 and has square portion 270 engaged by slot 256 so that movement of arm 254 rotates the washer on pin 266. The linkage maintains the separation of lenses 174, 176 at the distance "x-f 2 ". A further pivot pin 276 is secured to frame 54 in the same plane as pin 266, parallel to the optical axis, and is engaged by slot 260 in arm 252. Pin 276 is spaced from film 92 by distance "x+f 2 ".