Diazotype developing apparatus with improved liquid metering assembly

Claim 1

Apparatus for developing exposed diazotype sheet material by applying a predetermined small amount of liquid developer to the sheet material, said apparatus comprising: a frame; an applicator roller mounted for rotation in a given direction upon the frame, said roller having a generally cylindrical surface; a metering blade assembly mounted upon the frame and urged against the surface of the applicator roller; means for supplying liquid developer at a first area of the roller surface located before the metering blade assembly in a direction opposite to said given direction; and means for urging the sheet material against a second area of the roller surface located beyond the metering blade assembly in said given direction; said metering blade assembly including a fine mesh screen biased into direct contact with a portion of the roller surface between the first and second areas for metering the supplied liquid developer to establish an accurately determined amount of liquid developer upon the surface of the roller as the surface passes across the screen; said fine mesh screen including opposite surfaces, filaments intersecting at intersections along the screen, opposed flattened lands on said opposite surfaces and located on the filaments at intersections thereof, and a predetermined thickness between said opposed flattened lands.