Inspection device for high-speed prints

Claim 1

An inspection device for prints traveling at high-speed, comprising; a housing having an optical axis; means mounting said housing adjacent a plane in which a plurality of like prints are fed successively and one after another, at high speed in one direction past said housing, and at right angles to said optical axis, an even-numbered polygonal prism mounted in the housing so as to rotate about an axis extending at a right angle to said optical axis and passing coaxially through a longitudinal central axis of the prism, means for projecting images of said prints through a front window which is provided in the housing at the side thereof confronting said plane in which said prints travel, and to the eye of an observer through a further window provided in the housing oppositely to said front window, and which windows lie on said optical axis; said polygonal prism being rotatable in a direction opposite to said one direction, and means on said housing operable to cause said prism to be rotated at a speed synchronized with the running speed of the prints which travel at a right angle to said optical axis, thereby to cause stationary superimposed images of said prints to be projected to the eye of said observer.