Microfilm reader

Claim 1

A PORTABLE MICROFILM READER FOR READING FLAT MICRORECORD CARDS INCLUDING A LIGHTPROOF HOUSING HAVING A MOVABLE COVER MOUNTING A VIEWING ELEMENT ADAPTED TO BE STORED WITHIN THE HOUSING PROPER AND TO BE WITHDRAWN FOR DISPLAYING THE VIEWING ELEMENT WHEN A MICRORECORD CARD IS TO BE READ, SAID COVER FURTHER MOUNTING A LIGHT REFLECTING ELEMENT SPACED FROM SAID VIEWING ELEMENT FOR REFLECTING LIGHT RAYS DIRECTED THERETO TO SAID VIEWING ELEMENT, SAID HOUSING FURTHER INCLUDING AN OPENING TO ALLOW A MICRORECORD CARD TO BE INSERTED INTO THE HOUSING, A PAIR OF TRANSPARENT PLATES HAVING EDGES ALIGNED WITH SAID OPENING AND ADAPTED TO HOLD A MICRORECORD CARD THEREBETWEEN IN AN OPTICALLY FLAT POSITION WITHOUT EXTERNAL PRESSURE AND YET ARE SEPARABLE IN RESPONSE TO THE PRESSURE EXERTED BY A CARD POSITIONED IN SAID OPENING TO ALLOW THE CARD TO BE SLIPPED BETWEEN THE PLATES FOR READING, A LIGHT SOURCE INCLUDING A LIGHT CONDENSING SYSTEM ARRANGED WITHIN SAID HOUSING ON ONE SIDE OF SAID PAIR OF TRANSPARENT PLATES, A PROJECTION LENS SYSTEM ARRANGED ON THE OPPOSITE SIDE OF SAID PLATES FROM SAID CONDENSING SYSTEM TO RECEIVE THE LIGHT IMAGES FROM A MICRORECORD CARD HELD BY THE PLATES SAID PROJECTION LENS SYSTEM BEING DEFINED TO MAINTAIN REASONABLY SHARP FOCUS WITH THE MICRORECORD IMAGES AT ANY SELECTED POSITION OF THE PLATES AND PROJECTING THE IMAGES ONTO THE LIGHT REFLECTING ELEMENT MOUNTED ON THE COVER TO ALLOW THE CONTINUOUS SEARCHING OF A MICRORECORD CARD WITHOUT AUXILIARY FOCUSING WHEN THE COVER IS WITHDRAWN, SAID PROJECTION LENS SYSTEM COMPRISING A PROJECTION LENS HAVING A PRESELECTED FOCAL LENGTH MOUNTED IN A PRESELECTED SPACED RELATIONSHIP WITH A MICRORECORD HELD BY SAID PLATES FOR RECEIVING THE LIGHT RAYS TRANSMITTED THROUGH SAID PAIR OF PLATES, ANOTHER LIGHT REFLECTING ELEMENT MOUNTED ADJACENT SAID PROJECTION LENS FOR RECEIVING AND REFLECTING THE LIGHT IMAGES OF THE MICRORECORD TO SAID FIRST MENTIONED LIGHT REFLECTING ELEMENT, SAID PLATES BEING MOVABLE AS A UNIT AND BEING DEFINED AND CONSTRUCTED TO CONTINUOUSLY MAINTAIN THE MICRORECORDED IMAGES IN OPTICAL ALIGNMENT WITH THE PROJECTION LENS, AT LEAST THE HOLDING PLATE ARRANGED ADJACENT THE LIGHT PROJECTING SYSTEM HAVING A CONTROLLED THICKNESS DEFINED RELATIVE TO THE FOCAL LENGTH OF SAID SYSTEM TO MAINTAIN THE MICRORECORD IN CONTINUOUS FOCUS, AND CONTROL MEANS CONNECTED WITH SAID MOVABLE PLATES FOR OPERATING SAME THROUGH A SEARCHING MOVEMENT WHILE READING THE IMAGES ON THE VIEWING ELEMENT TO THEREBY ALLOW THE CARD TO BE SEARCHED FOR SELECTING A PARTICULAR PORTION OF THE MICRORECORD CARD FOR READING.