Latch for movie screen casing

Claim 1

A PORABLE MOVIE SCREEN DEVICE, COMPRISING: A STANDARD ADAPTED TO BE SUPPORTED IN AN UPRIGHT POSITION, THE STANDARD INCLUDING AN EXTENSION MEMBER FOR VARYING THE HEIGHT OF THE STANDARD, SAID EXTENSION BEING PROVIDED WITH A FREE END; CLAMPING MEANS FOR SECURING THE EXTENSION MEMBER IN A DEPRESSED POSITION AND IN VARYING DEGREES OF EXTENDED POSITION WITH RESPECT TO THE STANDARD; A SCREEN CASING PIVOTED TO THE STANDARD FOR MOVEMENT BETWWEEN AN OPERATIVE POSITION AND AN INOPERATIVE STORAGE POSITION GENERALLY PARALLEL TO THE STANDARD, SAID CASING BEING PROVIDED WITH LIMITED LATERAL MOVEMENT RELATIVE TO THE STANDARD WHEN THE CSING IS IN DI PARALLEL POSITION; SPRING MEANS IN THE STANDARD ENGAGEABLE WITH THE LOWER END OF THE EXTENSION MEMBER WHEN SAID EXTENSION MEMBER IS IN SAID DEPRESSED POSITION SO AS TO NORMALLY URGE SAID EXTENSION MEMBER OUTWARDLY OF TEH STANDARD; AND YIELDABLE LATCH MEANS ON ONE END OF THE CASING FOR DETACHABLY ENGAGING THE FREE END OF THE EXTENSION MEMBER AFTER THE EXTENSION MEMBER IS DEPRESSED AND THE CASING IS MOVED TO SAID INOPERATIVE POSITION WITH THE LATCH MEANS SUBSTANTIALLY LATERALLY ALIGNED WITH THE FREE END OF THE EXTENSION MEMBER, SAID FREE END AND LATCH MEANS ENGAGING IN LOCKING RELATION WHEN THE CASING IS MOVED LATERALLY TOWARD THE STANDARD TO HOLD THE CASING IN PARALLEL RELATION WITH RESPECT TO THE STANDARD.