Abstract: A process for engraving printing surfaces with unmodulated energy beams by interposing a variable reflectivity mask between the energy beam source and the printing surface. The local reflectivity of the mask varies in correspondence with the tone graduation of the original to be printed and may be formed by conventional photographic or the like techniques directly on the printing surface or on a substrate carrier through which the energy beam is passable.

Abstract: A method and apparatus for determining the relative position between a doctor blade and a printing cylinder in a rotogravure printing process in which the thickness of the layer of residual ink which is allowed to pass by the doctor blade is used as a control valve. The thickness of the residual ink is determined by determining the amount of the attenuation caused by the residual ink to a beam of light. In one embodiment a laser beam is impinged upon the residual ink on the printing cylinder and the portion of the laser beam which is reflected, absorbed, and scattered by the residual ink and the printing cylinder is detected. The thus detected light can be compared to a reference value for determining the attenuation due to the residual ink layer and hence determining the thickness of the ink layer. The thickness of the ink layer can in turn be used as a control value for adjusting the position of the doctor blade with respect to the printing cylinder.

Abstract: A method and apparatus for removing surplus ink from the surface of rotogravure printing cylinders by providing a doctor blade apparatus having an edge adjacent to but spaced from the surface of a rotating printing cylinder. The printing cylinder carries surplus ink and the doctor blade apparatus is disposed at some angle .alpha. with respect to a tangent to the printing cylinder and functions to remove all but a residual portion of the ink on the printing cylinder. To achieve this, the doctor blade is oscillated at a frequency sufficient to create a hydrodynamic barrier in the ink layer. This hydrodynamic barrier or turbulence in the ink layer at the doctor blade apparatus serves as a barrier for blocking passage of all but a predetermined desired residual portion of the ink layer past the oscillating edge of the doctor blade apparatus. The doctor blade apparatus can take many forms and can be oscillated in any desired manner.

Abstract: Depth measuring apparatus especially useful for measuring the depth of cells formed in a material layer, such as a rotogravure printing cylinder. An ultrasonic transmitter/receiver is adjustably mounted to a coupling element which is adjacent a surface having cells therein whose depth is to be measured. The position of the ultrasonic transmitting/receiving unit is adjustable with respect to the coupling element so as to adjust the angle at which the ultrasonic beam is impinged upon the material layer with respect to the plane of the material layer. The coupling element itself also has adjustment means associated therewith for adjusting the angle at which the ultrasonic beam is impinged on the material layer with respect to the plane of wall portions of cells formed in the material layer.

Abstract: Method and apparatus for engraving the cells of a printing surface to a controlled amount by controlling the spatial distribution and time duration of the trajectory of an energy beam having a cross-section smaller than the cell to be engraved thereby.