Roland Offsetmaschinenfabrik Faber & Schleicher Ag

Man Roland Druckmaschinen Ag

Grapho Metronic Mess- Und Regeltechnik Gmbh & Co. Kg

Peter Schramm

Alfred Dorn

Siegfried Schuhmann

Edgar F Schoneberger

Bert Cappel

Harry M Greiner

Gerd Steiner

Gunther Schniggenfittig

Gerhard Augsberg

Klaus Wolf

Walter Feulner

Jurgen Kramp

Oded Zingher

As ink is conveyed through the inking unit of a printing machine, a state of equilibrium occurs which ensures adequate inking of the printing plate during continuous printing. The equilibrium state includes different ink gradients for the respective printing zones superimposed on a uniform base level. In order to achieve the state of equilibrium rapidly and easily at the start of printing, an ink distribution is produced in the inking unit before printing closely matching the state of equilibrium for continuous printing. An accurately defined ink film distribution is initially fed to the inking unit rollers via the vibrator. Preferably, when the ink applicator rollers are thrown off of the plate cylinder and the sheet feed is off, a predetermined amount of ink is introduced to the inking unit. The vibrator is then shut off and the base level of ink is allowed to become uniformly distributed. Next the ink profile is set at the ink metering elements and the vibrator is turned on. When the ink profile propagates to the applicator rollers, the applicator rollers are thrown on to the plate cylinder and the sheet feed is turned on.

Inking unit pre-adjustment method

An apparatus to obtain ink density data by scanning color measurement strips on a printed sheet has a densitometer mounted on a digitally-driven X,Y positioning mechanism, an optical sensor for detecting the position and orientation of the sheet with respect to the X,Y positioning mechanism, and a numerical computer for transforming the sheet coordinates of the color measurement strips to the X,Y coordinates of the X,Y positioning mechanism. Thus, the numerical computer can automatically position the densitometer to scan the color measurement strips. In a first embodiment, optical sensor arrays determine the position and orientation of the test sheet with respect to the X,Y positioning mechanism. In a second embodiment, the densitometer itself scans the edge portions of the test sheet to determine the position and orientation of the test sheet. The operator has the option of using sheet coordinates of the color measurement strips obtained from non-volatile storage, from a recording medium such as magnetic tape or disk, from direct operator entry from a keyboard, or from the sighting of the measurement strips on the test sheet arbitrarily positioned and oriented with respect to the X,Y positioning mechanism.

Apparatus for determining and evaluating color measurement strips on a

Color control strips of sheets in a multi-color printing press are monitored by a light beam which is reflected by successive increments of the patches of the strip and passes through the filters of a filter wheel. The thus obtained color density signals are stored in memories, one for each color and each capable of storing the entire density profile of a patch. When the memories are filled to capacity, the admission of each fresh signal entails the eradication of the oldest stored signal. The stored profiles are evaluated by a microcomputer which discards certain signals and processes the remaining signals to ascertain the boundaries between neighboring patches, the center of the patch following the last-ascertained boundary, and the color density at the center of such patch. The evaluation can involve a comparison of the oldest and most recent signals in each memory and the processing of the resulting difference signals, such as a comparison of each difference signal with a fixed or variable threshold value for the purpose of ascertaining the aforementioned boundaries. The centers of the patches can be ascertained by counting the number of monitored increments of the patch following the last-ascertained boundary.

Method and apparatus for monitoring and evaluating the quality of color

An ink fountain of the type having a plurality of metering blades arranged closely side-by-side and having a metering edge which is presented to the fountain roller. The metering blades are divided into small groups of equal size with each group being supported upon a moveable carrier. A set of stops are interposed between each blade and its carrier to define (a) an extended reference position in which the pesented edges of the blades on the carrier are in alignment and (b) a relatively retracted feeding position in which the blade is retracted a predetermined amount to define a gap for feeding of ink in the zonal position controlled by the blade. Each blade has a spring for biasing it forceably into its extended position; an individual power actuator is interposed between each blade and its carrier for retraction of the blade into its feeding position. A control device is provided for activating the actuators for periods of time which correspond to the ink requirements of the zonal position including provision for ensuring that at all times at least one of the metering blades in each group occupies its extended reference position. A biasing spring interposed between the frame of the fountain and each carrier urges the carrier in the direction of the fountain roller so that the extended blade thereon acts as a local gauging device for the retracted ones of of the blades in the group.

Arrangement for metering ink on the fountain roller of a printing press

A control system for optimizing the starting angle of a vibrating roller for production of an evenly distributed film of ink on the printing plate of a printing press, particularly an offset press, in which a reciprocating drive connection is provided between the press drive and the vibrating roller for reciprocation of the latter. A chart is provided for each one of a complete set of reference distribution starting angles for the vibrating roller, each chart showing for each starting angle a corresponding ink density distribution curve which, when matched to the observed ink density distribution in a printed product, provides direct reading of optimum starting angle. A variable phase changer is interposed in the drive connection leading to the vibrating roller for directly setting the starting angle to optimum value. In a preferred embodiment of the invention the charts are arranged angularly spaced on a rotatable carrier disc which is coupled to a first servo device, while the phase changer is coupled to a second servo device, the servo devices being coupled together by servo circuitry for angular coincidence at an angle which is manually set. When the disc is in reference position (for example, zero), the optimum starting angle is read off the chart, following which the disc and phase changer are set, simultaneously, to the optimum angle.

Device for determination of operating angle of distributor rollers

An automatic ink feed control for a printing machine. Several ink-dosing elements are arranged across the width of the printing machine for dosing the application of ink to a printing plate, and these ink-dosing elements are individually adjustable by an adjusting device. The ink density of several control areas on the printed material is measured by a scanning measuring device, and a computer control compares these measured ink densities to desired ink densities in order to effect control of the adjustment of the ink-dosing elements by the adjusting device.

Means for the control and regulation of the printing process on printing

A device for measuring ink film thickness in the inking system of a printing press which includes a pair of hollow transparent rollers, at least one of which is resilient so that when the rollers are in rolling engagement with one another and with an ink-carrying roller in the press, there is a longitudinally extending ribbon-like area of engagement between them through which an enclosed film of ink is fed in a thickness which varies in accordance with the thickness of the ink film in the press. A longitudinally extensive light projector in one of the rollers cooperates with a correspondingly dimensioned light collector in the other, the collector being coupled to a photocell having an output indicator. The projector and collector are both in the form of optical cross section transformers, the projector being coupled fiber-optically to an external light source. A filter assembly is interposed in the light path manually switchable for application, to the film, of light of complementary color. A logarithmic amplifier is used having an attenuator, coupled to the switch, for affecting the light level to compensate for differences in inherent opacity of the differently colored inks thereby to enable the indicator to respond directly in terms of film thickness regardless of color.

Device for measuring ink film thickness

An inking system for a printing plate having a printing density which varies arbitrarily from the leading end of the plate to the trailing end including a source of ink film, rollers arranged in series between the source and the plate cylinder, the last roller in the series being a form roller in contact with the plate, with at least one of the rollers being a vibrated roller. Thrusting means are provided for imparting reciprocating movement to the vibrated roller. Means are provided for establishing a succession of sources of control signal at different levels tailored to the printing density of the plate at corresponding points about the periphery. A reference member coupled to the plate cylinder commutates the sources to produce a phased control signal which varies with ink need about the periphery of the plate. The control signal is utilized to vary the instantaneous velocity of the thrusting means inversely with the printing density of the plate so that ink is deposited on successive peripheral portions of the plate in a thickness tailored to need. In a preferred form of the invention a control board is used to set up the succession of sources of control signal visually corresponding to the profile of printing density, and hence ink need, at successive peripheral portions of the plate. The vibrated roller is preferably interposed between the source of ink and the form roller, but in a modified form of the invention the form roller itself is vibrated with variation in instantaneous velocity.

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Kahl am Main, Germany

Peter Schramm