A drag force sensor on a fountain solution carrier roller surface measures drag force of a fountain solution layer on the fountain solution carrier roller surface in real-time during a printing operation. The measured drag force is used in a feedback loop to actively control the fountain solution layer thickness by adjusting the volumetric feed rate of fountain solution added onto the imaging member surface during a printing operation to reach a desired uniform thickness for the printing. This fountain solution monitoring system may be fully automated.

Examples of the preferred embodiments use printed content (e.g., halftones, difference in grayscale or darkness) to determine thickness of fountain solution applied by a fountain solution applicator on an imaging member surface and/or determine image forming device real-time image forming modifications for subsequent printings. For example, in real-time during the printing of a print job, a sensor may measure halftones or grayscale differences between printed content and non-printed content of a current printing on print substrate. Based on this measurement of printed content output from the image forming device, the image forming device may adjust image forming (e.g., fountain solution deposition flow rate, imaging member rotation speed) to reach or maintain a preferred fountain solution thickness on the imaging member surface for subsequent (e.g., next) printings of the print job.

According to aspects of the embodiments, there is provided a method of determining the amount of fountain solution employed in a digital offset lithography printing system. Fountain solution thickness is determined by examining optical density of some halftone or solid patch versus laser current level. The apparatus and method uses a variable current signal to dither or perturb the laser imaging system to irradiate a fountain solution layer to create patches at different laser current levels. An aptly programmed controller then process optical density measurements to indirectly estimate fountain solution level.

A service tracking system for a printing press (1), spray applicator (1′) or the like includes at least one replaceable component (10) having at least one memory unit (20). The service tracking system further includes a controller (30) which is connected to the memory unit (20). The controller (30) is configured to control the operation of the replaceable component (10) and to periodically update data stored on the memory unit (20) related to run-time data regarding the operation of the specific replaceable component (10).

A display device which is connected, in data terms, to a printing press, is controlled. A depiction of a printed image, which is printed onto a printing material by the printing press, together with a plurality of ink zones, arranged next to one another transversely, with respect to a transport direction of the printing material which is guiding through the printing press, of at least one inking unit, which is arranged in the printing press, are indicated on a display surface of the display device of a control unit in a controlled manner. The inking zones are indicated by way of parallel boundary lines, which delimit them in each case. For the display of the boundary lines which delimit the inking zones, the control unit fixes one of the color thereof and the brightness thereof and the opaqueness thereof in a manner which is dependent on a minimum contrast which has previously been set in the control unit, in order to form an image region, adjoining the boundary lines, of the printed image which is displayed on the image surface of the display device and displays the boundary lines which delimit the inking zones in the contrast ratio which is fixed in respect of the printed image which is displayed on the display surface of the display device.

A display device which is connected, in data terms, to a printing press, is controlled. A depiction of a printed image, which is printed onto a printing material by the printing press, together with a plurality of ink zones, arranged next to one another transversely, with respect to a transport direction of the printing material which is guiding through the printing press, of at least one inking unit, which is arranged in the printing press, are indicated on a display surface of the display device of a control unit in a controlled manner. The inking zones are indicated by way of parallel boundary lines, which delimit them in each case. For the display of the boundary lines which delimit the inking zones, the control unit fixes one of the color thereof and the brightness thereof and the opaqueness thereof in a manner which is dependent on a minimum contrast which has previously been set in the control unit, in order to form an image region, adjoining the boundary lines, of the printed image which is displayed on the image surface of the display device and displays the boundary lines which delimit the inking zones in the contrast ratio which is fixed in respect of the printed image which is displayed on the display surface of the display device.

An image based correction system compensates for the image quality artifacts induced by thermal ghosting on evolving imaging member surfaces. With thermal ghosting directly tied to previous image content, a feed forward system determines thermal ghosting artifacts based on images previously rendered and generates an open loop gray-level correction to a current image that mitigates undesirable ghosting. For example, the correction system compensates for the thermal ghosting by making the current image lighter in areas that will be imaged onto warmer blanket regions, thereby cancelling out TRC differences between different temperature regions. A temperature sensor is used to measure the temperature of the imaging blanket due to the stresses induced by the image. This data is used to learn the parameters of the temperature model periodically during operation, and used in subsequent corrections to mitigate thermal ghosting in spite of changes in blanket properties over use and time.

A dampening water amount regulating apparatus 40 includes a plurality of air supply boxes 41 disposed in a line in an axial direction of a water transfer roller 8 and each defines one air blowing portion. The air supply box 41 includes a substantially U-shaped air passage 67 that allows air in an air supply chamber 57 to pass along an outer peripheral surface of the water transfer roller 8 and supplies the same into an air discharge chamber 60. A valve mechanism 44 that increases and decreases an air amount is provided at a midsection of the air passage 67.

A device one of adjusts and changes a dampening medium profile, which extends in the direction of a printing width, in a printing unit comprising at least one printing unit cylinder, at least one inking unit which inks the printing unit cylinder, and at least one dampening unit which interacts with one of the printing unit cylinder and the printing unit. A drying device, which extends over the printing width, is provided with a number I(I, 0>1) of drying elements, the influence of which, on a printing unit surface to be treated, allows moisture to be removed from a number of n(n, n>1) axial portions a.sub.j(j=1, . . . , n) that are offset relative to one another in the direction of the printing width. One of an extent of the influence of the drying device with respect to the axial direction (a.sub.j) and the operating state of the drying device can be varied independently of one another. The drying elements are designed and arranged in the printing unit such that at least 20% of the width (b.sub.j), when seen in the direction of the printing width, of multiple or all of the axial portions (a.sub.j), which are designed as active portions (a.sub.j) with an active width (b.sub.j) of the drying elements in the printing unit, over the extension of those portions, overlaps with an adjacent axial portion of the axial portions (a.sub.j), which are axially offset relative to one another in the direction of the printing unit. A controller and one of a switching and an adjusting device, which are connected to the controller for signaling purposes, are provided. The controller and the one of the switching and adjusting devices are used to operate multiple or all of the drying elements during a stationary active operating state such that each of the drying elements is pulsed, i.e. is individually clocked between an off switching state and an on switching state.

A dampening water amount regulating apparatus 40 includes a plurality of air supply boxes 41 disposed in a line in an axial direction of a water transfer roller 8 and each defines one air blowing portion. The air supply box 41 includes a substantially U-shaped air passage 67 that allows air in an air supply chamber 57 to pass along an outer peripheral surface of the water transfer roller 8 and supplies the same into an air discharge chamber 60. A valve mechanism 44 that increases and decreases an air amount is provided at a midsection of the air passage 67.