Abstract: Radiation pulses are directed at a measuring spot on a rotating printing-image carrier in an offset printing press. The intensity of the radiation returned from the measuring spot outside of the angle of reflection of the pulse is measured for a predetermined wavelength. A pulse is directed at the measuring spot before printing and while the measuring spot is dry, and a signal representing the intensity of the returned radiation is stored in a working memory. During a subsequent printing operation, a dampening agent is applied to the printing-image carrier. In order to determine the amount of dampening agent on the printing-image carrier, radiation pulses are directed at the measuring spot as the printing-image carrier rotates during printing. The intensity of the returned radiation in the predetermined wavelength is converted into damp signals which represent the amount of dampening agent since the predetermined wavelength approximates or equals an absorption wavelength of the dampening agent.

Abstract: A printing plate is secured to the printing cylinder of an offset printing machine by clamping bars which are installed in the cylinder channel and carry gripping strips serving to hold the edges of the printing plate. The front edge of the printing plate is provided with cutouts for the tips of feelers forming part of electronic measuring devices which are mounted on the guide strips of the printing cylinder. The cutouts have a fixed relationship relative to images on the printing plate. The clamping bar for the front edge of the printing plate is adjustable with reference to the printing plate by tightening screws until the measuring devices indicate that the front edge is in zero position. The measuring devices thereupon indicate any deviations of the position of the printing plate from zero position with reference to the printing cylinder.

Abstract: An ink roller for a printing press having a cylindrical outer shell presenting a roller surface and having a control fluid-displacing core, a hollow cylindrical partition being interposed between the shell and the core to define inner and outer annular passageways connected in series having respective inlet and outlet openings. A source of cooling fluid is connected to the inlet opening so that a feed stream of cooling fluid flows longitudinally through the inner passage and turns around to form a cooling stream flowing in counterflow relation through the outer passage. The cylindrical partition is formed of conductive material so that heat absorbed at a given region of the roller surface by the cooling stream flows radially inwardly for absorption by the feed stream at substantially the same rate, so that the cooling stream has only minimum net gain or loss of heat; this tends to equalize the temperature along the length of the cooling stream and hence along the length of the roller surface.

Abstract: A system for facilitating throw-off and re-engagement of a blanket cylinder with respect to cooperating plate and impression cylinders and which minimizes wastage of copies incident to reestablishing equilibrium in the inking and dampening systems following an interruption of the normal printing process. Two separate control means are provided for controlling the rate of water flow, the first being an automatic control at the water fountain and the second being in the form of means for controllably disengaging the water form roller from the printing plate. Means are provided for switching from the first control means to the second when the blanket is disengaged for promptly cutting off the flow and thereafter maintaining a water film of predetermined thickness on the plate.

Abstract: Means for measuring and correctively changing the thickness of a film of water on the plate of an offset printing press which includes a light source forming a spot of light on the plate with light pick-up means including a photocell producing an output signal in response to remitted light. A disc carrying two filters in symmetrically spaced sectors is interposed in the path of the light reaching the photocell. The first filter is a band pass filter which passes a wavelength slightly separated from a maximum light absorption band of water. The second filter passes a wavelength which is well separated from the maximum light absorption band of water and which lies in a region of where there is minimum change of absorption as a function of film thickness. As a result the photocell is subjected to an alternating series of "measuring" light pulses and "reference" light pulses through the respective filters.

Abstract: An inking system for applying ink to a printing plate which includes a fountain roller and a series of ink feed rollers with at least one vibrated roller or drum. Means are provided for automatically regulating the temperature of the fountain roller thereby to maintain constant the amount of ink fed over a long press run for maintenance of a predetermined full tone density. Means are also provided for automatically regulating the temperature of the vibrated roller thereby to maintain constant the printing contrast in the half tone portions of the plate. The temperature regulating means includes both a source of heat and a source of cold, making it possible to either warm or cool the rollers thereby permitting automatic operation over a wide range of conditions including a wide variation in the ambient temperature. In the preferred embodiment the temperature of the rollers is maintained by circulating a fluid such as water through the rollers from a reservoir of fluid at a controlled rate and temperature.