Patent GB-707893-A (GB)
Title: Improvements in or relating to kinematic recording apparatus
Inventor: JUNGERMANN WERNER
IPC: G01D15/14
Filed: 1951-03-09
Abstract: 707,893. Recording-apparatus. NATIONAL RESEARCH DEVELOPMENT CORPORATION. June 9, 1952 [March 9, 1951], No. 5778/51. Class 106 (4) A recording-apparatus for obtaining a continuous record of the kinematic displacement of an object in a plane at high speed comprises projector means, including a source of light and a projector lens, arranged to direct a beam of parallel light on to the object normal to the plane of displacement and through a cylindrical lens onto a recording screen moving continuously transversely to the kinematic displacement in the focal plane of the cylindrical lens which is arranged with its axis perpendicular to the direction of movement of the screen so that a silhouette-like trace of the displacement of the object can be recorded on the screen as the object is moved across the beam of parallel light. The inter-relation of the source of light to the local length of the projector lens is such that the focal length of the projector lens is at least 2,800 times the radius of the source of light defined as one half of the maximum dimension of the effective area of the light source which is presented to the projector lens. In Fig. 1, two objects 6, 7 are moved in guides 4, 5 in the direction TS so that each obscures a portion of a flat parallel beam of light 1 directed towards a cylindrical lens 2 of short focal length which focuses a bright, thin line on a light-sensitive film 3 moved at constant speed in the direction of the arrow A in the focal plane of the lens 2 within a light-proof casing so that a full scale record is obtained of the displacements of the objects. Means are provided for projecting a time scale on the edge of the chart. In Fig. 2 a full scale diagram is obtained of the relative displacement of two connecting rods 10, 11 which provide for the reciprocation of two pistons 12, 13 by a crank shaft 14. The rods 10, 11 carry indicators 15, 16 shown at maximum separation with a line of light of maximum width brought to focus on the screen. As the crankshaft rotates the indicators 15, 16 approach one another and thus obscure a greater portion of the light beam. Suitable apparatus, Fig. 3, comprises a light source 20 comprising a mercury high pressure arc lamp having an arc of 0.02 X 0.027 inches enclosed in a light-proof casing 21 having an aperture 22 exposing only the most brilliant part of the arc whose rays pass into the rear end of a projector tube 23 provided at the front with a lens 24 of long focal length, e.g. 57 inches, which is focused on to the arc of the lamp 20 and produces a parallel beam of light, the focal length of the lens being at least 2,800 times the radius of the source of light. Aligned with the projector 23 is the object 29 and a recording camera 25 with a continuously movable film 28, a slot 26 and cylindrical lens 27 of short focal length, say less than 0.5 inches. If the object is within 2 feet of the film the record will be within the accepted limits of blurring of 0.004 inches, and the distance may be increased by increasing the focal length of the lens 24 or by reducing the radius of the source of light. The camera may be remotely controlled and it may be arranged to control the time the objects begin their movement which should be just after the film has reached a constant velocity.