Roland Offsetmaschinenfabrik Faber & Schleicher Ag

Man Roland Druckmaschinen Ag

Man Roland Druckmaschinen

Alfred Dorn

Peter Schramm

Edgar F Schoneberger

Bert Cappel

Siegfried Schuhmann

Joachim Muller

Burkhardt Wirz

Gunther Schniggenfittig

Rolf Braun

Peter Decker

Klaus Wolf

Valentin Gensheimer

Oded Zingher

Method and apparatus for scanning an ink test strip printed on a sheet, the sheet being positioned on a table traversed in two directions by a scanning head. The table includes guide means including a bar for positioning the sheet in a first dimension and an index mark for positioning the sheet and its associated test strip in a second dimension. The scanning head indexes to the index mark which physically establishes a first coordinate for the test strip. Thereupon, the scanning head indexes in a second direction to automatically locate the test strip based on the size of the test strip as sensed by the densitometric sensing device associated with the scanning head. Having located the second coordinate Y.sub.s for the initial test patch of the test strip, the system then initiates the scan along the test strip to measure the optical density of each test patch relating to each printed zone on the sheet.

Densitometric sensing device for use in printing presses

A light-emitting diode is used both for receiving data from an operator to change the logic state of a device and for displaying the entered data back to the operator. Current is selectively applied to the diode to display the data, but on an alternate basis the photo-current produced in the light-emitting diode by surrounding illumination is sensed and the data are received by detecting the fall-off in the photo-current caused by the operator covering the light-emitting diode. This technique is advantageously employed for the input and display of ink slide settings for a rotary printing machine by using a light-emitting diode matrix or bar graph display subject to finger-tip control by the operator. The diode matrix is scanned by repetitively and sequentially inhibiting the lighting current to the individual light-emitting diodes so that they may be sequentially connected to a photo-current monitoring circuit via a multiplexer under control of a clock circuit.

Control device using light-emitting diodes for both manual input and

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

An apparatus for determining the position of a sheet when the sheet is placed on a support having at least two spaced apart CCD linear image sensors recessed in the sheet support and partially covered by the edge portions of the sheet. The CCDs operate as line cameras, and are scanned to generate signals correlated with the points of intersection of the sheet edges and the axes of the image sensors. Preferably the apparatus has circuitry for storing calibration values of the CCD signals obtained when the image sensors are not covered by the sheet, circuitry for storing corresponding scanning signal values when the image sensors are covered by the sheet, circuitry for comparing corresponding calibration and scanning values for obtaining difference values, and circuitry for detecting maxima in the gradient of the difference values for adjacent image points to find the locations of the points of intersection of the sheet edges and the axes of image sensors. These locations are used by software driving an X-Y plotter head or by a sheet positioning mechanism to correct for variations in sheet position.

System for detecting the position of a sheet on its support

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

An ink metering system for a printing press for metering ink to individual column positions on a printing plate in which the fountain blade is formed in individual sections having power actuators to establish film-forming gaps at corresponding positions. Linear follow-up potentiometers are provided having their slides respectively coupled to the blade sections so that when the potentiometers are connected to a source of reference voltage, and the sections initially adjusted, the slider voltage provides a direct indication of the width of the gap. To change the setting over the entire width of the blade, a variable voltage supply is provided with a control for shifting the voltage from reference level to a calibrated level of offset voltage, on one side or the other of the reference, to bring about a percentage change in voltage at each of the adjustable blade sections. To create a voltage differential for follow-up purposes, each actuator has a voltage storage, or 'memory', device together with a voltage 'comparator' to produce an output dependent upon the algebraic sum of the 'new' and 'old' voltages. Such output energizes the actuator to move each blade section and potentiometer slider to a new position in which all of the gaps are changed in the same direction and as a fixed percentage of their initial settings.

Device for adjustment of the ink flow on printing press inking units

A control system for a reversible screwing tool for tightening and loosening screws in a printing press or the like which includes a pair of angularly spaced pick-up devices coupled to the shaft of the tool for generating respective series of impulses. Monostable pulse generators are coupled to the respective pick-up devices, the generator coupled to the pick-up device in leading position, for counterclockwise rotation, being set to produce an output pulse which is substantially wider than that produced by the generator which is connected to the pick-up device in trailing position so that during counterclockwise rotation the output pulses from the generators timingly overlap one another. The generators feed into the input terminals of an AND gate which is, in turn, connected to a counter which counts the pulses resulting from counterclockwise rotation of the shaft. A relay interposed between the source and the tool automatically turns off the tool when a predetermined count is achieved thereby insuring that the screw is not excessively unscrewed from its tight condition. The relay is resettable in readiness for engagement of the succeeding screw. In the preferred embodiment of the invention the generator which is coupled to the pick-up device in leading position is responsive to the trailing edge of the received impulse while the generator connected to the pick-up device in trailing position is responsive to the leading edge of the pulse which it receives.

Screwing tool for printing presses

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

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. Simultaneously with disengagement of the blanket cylinder the ink feed rolls are declutched and the ink form rollers are disengaged for promptly cutting off flow of ink to the plate while preserving the film thickness gradient which exists in the ink feed system. A blanket cleaner is incorporated together with means for spraying solvent on the ink feed rolls. The throw-off mechanism is so arranged that, upon resumption of normal printing, the blanket is brought into engagement with the plate for a predetermined interval before it is engaged with the impression cylinder, thereby insuring that the blanket is re-inked to optimum degree before contact is made with the impression cylinder. As the blanket is brought into engagement with the plate, the inking system, with its pre-existing gradient, is reactivated and the control of water flow, after a delay interval, is restored to the water fountain, permitting the immediate printing of perfect copies.

Growing community of inventors

Lammerspiel, Germany

Alfred Dorn