EP1036655A1 - Production d'une image sur une plaque d'impression pour l'impression offset humide - Google Patents

Production d'une image sur une plaque d'impression pour l'impression offset humide Download PDF

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Publication number
EP1036655A1
EP1036655A1 EP00810209A EP00810209A EP1036655A1 EP 1036655 A1 EP1036655 A1 EP 1036655A1 EP 00810209 A EP00810209 A EP 00810209A EP 00810209 A EP00810209 A EP 00810209A EP 1036655 A1 EP1036655 A1 EP 1036655A1
Authority
EP
European Patent Office
Prior art keywords
ink
printing
printing form
cylinder
dampening solution
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP00810209A
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German (de)
English (en)
Inventor
Matthias Riepenhoff
Yufan Jiang
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Wifag Maschinenfabrik AG
Original Assignee
Wifag Maschinenfabrik AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Wifag Maschinenfabrik AG filed Critical Wifag Maschinenfabrik AG
Publication of EP1036655A1 publication Critical patent/EP1036655A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
    • B41C1/00—Forme preparation
    • B41C1/10—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme
    • B41C1/1075—Mechanical aspects of on-press plate preparation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
    • B41C1/00—Forme preparation
    • B41C1/10—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme
    • B41C1/1008—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme by removal or destruction of lithographic material on the lithographic support, e.g. by laser or spark ablation; by the use of materials rendered soluble or insoluble by heat exposure, e.g. by heat produced from a light to heat transforming system; by on-the-press exposure or on-the-press development, e.g. by the fountain of photolithographic materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
    • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
    • B41C2210/04—Negative working, i.e. the non-exposed (non-imaged) areas are removed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41P—INDEXING SCHEME RELATING TO PRINTING, LINING MACHINES, TYPEWRITERS, AND TO STAMPS
    • B41P2227/00—Mounting or handling printing plates; Forming printing surfaces in situ
    • B41P2227/70—Forming the printing surface directly on the form cylinder

Definitions

  • the invention relates to a method and a device for imaging a Printing form for wet offset printing.
  • the invention in Newspaper offset printing, preferably newspaper offset roll printing, used.
  • a directly imageable printing form cylinder is known from US Pat. No. 5,293,817.
  • the Printing form cylinder has a porous outer jacket.
  • the dampening is done by the inside of the cylinder through the porous outer jacket.
  • the porosity of the Cylinder jacket is between 20 and 45%.
  • the diameter of the pores of the Cylinder jacket decreases towards the outside of the cylinder jacket and lies between 3 and 100 ⁇ m.
  • the pores of the cylinder jacket communicate with each other.
  • the illustration takes place via a thermal transfer or an inkjet method by means of an image information transmission device.
  • the use of a heated electrode mentioned in pin form to apply oleophilic material to the cylinder jacket.
  • the invention relates to a method for imaging a printing form for a Wet offset printing, which is on an unimaged surface of the printing form Print image created by forming ink-accepting and ink-repellent areas becomes.
  • the surface is illustrated and also unillustrated because of its Function of the transfer of color in the following as a color transfer surface designated.
  • the print image is generated, i.e. the illustration by the still unimaged ink transfer surface is wetted with a dampening solution, those areas of the moistened surface that are to be ink-accepting, targeted, i.e. according to the image, dried and then material, the printing ink accepts and preferably rejects dampening solution on the ink-transferring surface is applied to the dry areas.
  • the material is preferably as soon as possible after the applied according to the image drying of the ink-transferring surface so that the Do not use dried areas again before applying the ink-accepting material Fountain solution are wetted.
  • a dampening film that wets the ink-transfer surface should be averaged over the area of an image pixel, at most 1 ⁇ m thick, by the evaporation energy to keep low.
  • the thickness is preferably between 0.2 and 0.5 ⁇ m set.
  • the method can be modified such that Imaging first a flowable material evenly on the ink-transferring Surface is applied, the ink accepts and dampening solution preferably rejects this material in a targeted manner at the points to be trained to accept the color hardened or hardened and in the paint-repellent areas where it is still flowable, is removed using dampening solution.
  • the two process alternatives mentioned have the advantage that initially the ink-transferring surface is evenly wetted or covered, for what once Fountain water and once ink accepting and dampening repellent material used and then the evenly wetted or covered surface of the printing form by drying the dampening solution or hardening, especially drying, the ink-accepting / dampening agent-repellent material specifically with the printed image in which the dried spots or the spots with the hardened material form ink-accepting areas.
  • An application device with which an ink-accepting and dampening agent-repellent material is applied directly according to the picture It is not necessary to carry out the method according to the invention.
  • Any application of material is considered a uniform application in the sense of the invention understood for the purpose of illustration, which is not itself already done according to the picture. Preferably done the application of material over the entire surface of the printing form or at least in Surface stripes evenly.
  • the ink-accepting / dampening agent-repellent material is preferably printing ink, particularly preferred printing ink of the current production in which the illustrated printing form then used.
  • a particular advantage of the method according to the invention in both alternatives is that to apply the ink-accepting and preferably dampening agent-repellent material in the course of the imaging, a paint application device that is available anyway for ongoing production, for example, an ink roller can be used.
  • the usage such an ink application device, in particular an ink roller also corresponds a particularly preferred embodiment of the invention.
  • a separate application roller or other suitable application device for example a spraying device, only for illustration or for illustration and for the subsequent paint application may be provided. After all, should also be in such training the material order is not controlled according to the image.
  • the immaterial treatment according to the invention according to the image of a previously uniform the ink-transferring surface of the printing material or Dampening solution also allows more precise image formation than that of an immediate one pictorial material application is possible.
  • the invention further relates to a device for imaging a printing form in a Rotary printing machine for wet offset printing.
  • the machine is preferably a web press for newspaper offset.
  • the device comprises a printing form cylinder with the printing form, a dampening device for wetting a color transfer surface of the printing form with dampening solution and a Application and image transfer device, with the on the color transfer surface by applying an ink-accepting and dampening-repellent material a printed image with ink-accepting areas and dampening solution-accepting areas is produced.
  • the application and image transmission device has an application means for even application of a flowable material that accepts printing ink and Preferably rejects dampening solution, and an irradiation device, preferably Exposure device on.
  • the print image is created by a combination of material application by means of the application means and irradiation of those places of the ink-transferring Surface created by means of the irradiation device to form the ink-accepting are.
  • the application means is preferably an application means that is in transfers the printing ink to the printing form cylinder during ongoing production.
  • each of these printing form cylinders such an order and image transmission device assigned.
  • machine size i.e. Number of printing form cylinders
  • the cost advantages grow with the direct imaging according to the invention especially when the print production changes frequently and downtimes are minimized should be.
  • the invention further relates to a dampening medium-permeable printing form and a method for the production of such a printing form. It is a printing form for a wet offset rotary press.
  • the printing form has an imageable or Imaged surface for transfer of printing ink.
  • the unimaged printing form is at least on a ink-transferring surface dampening agent friendly or accepting, preferably hydrophilic.
  • the printing form can, like also known printing forms, for example a printing plate or preferably one Printing form shell, which is attached to a carrier cylinder, for example by means of a known clamping device.
  • Such intrinsically stable, imageable or illustrated Printing forms as such are also the subject of the invention.
  • the carrier cylinder in this case forms the printing form cylinder together with the attached printing form.
  • the printing form can also be a cylinder sleeve.
  • Printing form sleeve Disadvantage of such a Printing form sleeve, however, would be that the carrier cylinder only rotatably supported on one side could be to be able to change the printing form sleeve in a simple manner.
  • printing form cylinders the subject of the invention that an imageable or already have illustrated printing form on a cylinder surface, the printing form cannot be removed; at least the printing form cannot in this training be removed non-destructively.
  • the printing form is permeable to a dampening solution in a radial direction.
  • the direction is indicated on a pressure plate that is attached to a carrier cylinder related to the assembled state.
  • the printing form cylinder including printing form has a device by means of which the dampening solution can be guided to the printing form.
  • the carrier cylinder becomes the cylinder body of the printing form cylinder understood, on which the printing form is attached, either as an independent Pressure plate or, as already stated above, as an integral part.
  • the dampening solution in particular fountain solution, from the back the printing form brought to the ink-transferring surface of the printing form.
  • the dampening of the printing form i.e. the color transfer surface
  • the dampening of the printing form i.e. the color transfer surface
  • the color acceptance or rejection by a targeted closing of passage channels on the ink-transferring surface become.
  • no dampening solution can reach the ink-transfer surface, so that in the one enclosing the through-channel Color area is accepted.
  • the color transfer surface is basically perforated first closed surface can be produced
  • the printing form preferably has as Print layer on an outer layer of material that is porous.
  • the printing form is built up in layers according to the invention and has an outer Print layer with the imageable or illustrated surface and one adjacent underlying lower layer.
  • the throughflow capacity preferably increases Printing form abruptly at an interface from the lower layer into the printing layer Multiple off.
  • the flow resistance increases accordingly.
  • these two layers can consist of different materials and also thereby be optimally adapted to different functions according to the invention.
  • flow-through means the volume of the used Understanding dampening solution, which is covered by a layer with an executed thickness flows to a differential pressure acting over this layer per time and area, the outer surface of the layer being taken as the surface.
  • the flowability is used as a material characteristic in the following on the unimaged condition of the color-transferring surface.
  • An abrupt decrease in the sense of the invention is not only a sudden, for the practical concerns as a change in the flowability that can be regarded as inconsistent understood, but also a constant change.
  • the flowability shows a steep gradient at the transition from the lower layer to the printing layer on.
  • a transition zone from the lower layer that can never be completely avoided in practice into the pressure layer in which the change in flowability according to the invention takes place is in any case thinner than the print layer. According to the invention, it becomes a The steepest possible decrease in flowability from the lower layer into the pressure layer sought.
  • the underlayer is first formed, preferably by a fleece of rust-free metal fibers.
  • a fleece advantageously has a high tensile strength compared to materials of the same porosity Compressive strength.
  • Sintered and rolled to a defined thickness made of non-rusting Metal fibers are particularly suitable.
  • Suitable nonwovens are from filter technology known.
  • the printing layer is made by coating the underlayer, preferably by means of Plasma spraying received. It is preferably formed as a ceramic layer.
  • the flow resistance becomes due to the layered structure of the printing form according to the invention or the flowability of the printing form as a whole in a practical approximation determined solely by the print layer.
  • the printing layer preferably has a uniform material structure and, last but not least, the required fineness of pressure can be optimally adapted. Their structure or structure is such that it is traversed by capillary pores that are very fine and on the color-transmitting Have a high surface density. Per image pixel ends on the surface at least one such capillary pore. At the same time, the porosity of the print layer kept low. It is preferably below 20%. It is an open one Porosity.
  • the printing form is particularly preferred in combination with the invention Imaging method and / or used in a device according to the invention. However, it is not limited to this, but also in combination with conventional ones Methods and devices for imaging internally moistened printing forms usable for profit.
  • the passage channels of the pressure layer which preferably have the The aforementioned capillary pores are, in particular, an average diameter of 0.1 to 5 ⁇ m measured at the mouths on the ink-transferring surface.
  • the porous printing layer preferably has a on the ink-transferring surface Average roughness Ra in the range of 0.2 to 5 ⁇ m and preferably an average Roughing depth Rz in the range from 0.2 to 10 ⁇ m.
  • the lower layer is traversed by through channels, for example connected pores, which have a diameter of 10 microns to 2 mm, preferably 10-50 microns.
  • Diameter is understood to mean the diameter of a circle, which is the average cross-sectional area the passage channels of the respective layer.
  • Will it be through a fleece is used to characterize the laminar diameter, determined analogously to ASTM F 902, the right size.
  • the laminar diameter should then be between 10 and 100 ⁇ m.
  • the printing layer preferably has a high absorption coefficient for infrared radiation on.
  • the absorption coefficient should be at least 0.9.
  • the dampening solution is preferably by infrared radiation is evaporated and it is in the near infrared when using fountain solution as a dampening solution only for a low absorption of preferably used infrared Laser radiation comes in the dampening solution film, it heats up and evaporates a dampening solution takes place indirectly by heating the printing layer.
  • the material for the print layer preferably selected a material with a heat capacity that is less than that Heat capacity of the dampening solution.
  • the heat capacity of the is particularly preferred Print layer less than 1 J / g.
  • the printing layer is formed so that the Thermal conductivity of this layer is significantly lower than the thermal conductivity of the dampening solution is.
  • the thermal conductivity is preferably less than 0.2 W / (m * K).
  • a perforated printing form carrier has holes with a diameter, preferably in Range of 0.5 to 5 mm or recesses of the same area on the whole Range of the printing form from one another, preferably in the range from 5 to 50 mm have.
  • the hole density can be significantly reduced by the areas enlarged per hole and / or one on the outer surface of the printing form support Channel structure is formed.
  • the underlayer is applied to the printing form support, in particular as a whole attached to it, preferably glued using a temperature-resistant adhesive or bonded.
  • the amount of dampening solution exiting the ink-transferring surface per unit of time is regulated by setting the dampening solution pressure, advantageously by the Setting the amount of dampening solution in the printing form cylinder.
  • the dampening solution pressure By increasing the amount of dampening solution due to the centrifugal forces, the Dampening solution pressure increased. Furthermore, the dampening solution supply rate becomes the printing form cylinder increased and decreased in proportion to the printing speed.
  • the amount of dampening solution exiting the ink-transferring surface per unit of time i.e. the flow rate of the printing form depends on one which is completely sufficient for practice Approximation only from the flow through the outer pressure layer.
  • the Pressure difference across the outer pressure layer increases at a constant rotation speed approximately linear with the dampening solution level, which is on the back of the printing layer sets.
  • the flow through the pressure layer can be determined solely by the thickness of the Adjust the print layer, since the print layer is essentially constant everywhere Porosity and capillary pore density. In this sense, the lower layer is also homogeneous.
  • dampening solution film on the The surface can be set precisely, especially very small.
  • Cylinder speed is exactly as much dampening solution on the back of the printing form out how to exit the ink-transferring surface.
  • the equilibrium height of the dampening solution level in the lower layer on the back of the printing layer arises then on its own depending on the speed of the printing form cylinder.
  • the Setting when changing the speed is also done because of the invention Construction of the printing form almost without delay.
  • the overpressure on the back of the print layer should not exceed 100 mbar.
  • the dampening solution level on the back of the print layer should at least be in equilibrium of inflow and outflow do not exceed the thickness of the lower layer.
  • Corresponding the thickness of the underlayer and the permeability of the printing layer are preferred coordinated.
  • a preferred way of closing is by heat-induced, preferably laser-induced, image-dependent toning.
  • wet offset printing is based on the repulsion of paint by dampening solution on the moistened areas of the Printing form. If there is not enough dampening solution, color will be accepted also at the non-image areas. This process is commonly referred to as toning.
  • the ink-transferring surface of the printing form moistened from the inside and then by means of the image transmission device, preferably using infrared laser, dried depending on the image.
  • the image transmission device preferably using infrared laser
  • the image points dried and immediately colored.
  • coloring color is applied to the transfer dried areas, while the moist areas remain color-free.
  • the paint clogs the passageways, leaving those areas no more dampening solution penetrates to the ink-transferring surface.
  • the illustration of the printing form i.e. the color dried in the passage channels, can be removed by a conventional printing plate washer and / or due to the internal humidification with a higher dampening solution pressure than the production.
  • a sub-variant can be used the second process alternative also a monomer or mixture of monomers the ink-transferring surface of the printing form are applied, in particular be sprayed on.
  • a polymerization is carried out by means of the image transmission device triggered.
  • the plastic formed thereby closes the passage channels, e.g. by Formation of polystyrene from styrene when exposed to heat.
  • the closed pores can be freed by rewarming the polymer again disintegrates and is removed by adding dampening solution.
  • the dampening solution is at the deletion of the image preferably fed from the inside. Washing from the outside is however also possible, especially supportive.
  • the printing form and lead in an exposure process for imaging the printing form the image transmission device has a predefined direction and speed Relative movement in which the surface of the printing form to be imaged pixel by pixel is exposed image-wise.
  • a pixel column therefore runs in Column direction and a pixel row in a row direction perpendicular to it.
  • the above relative movement takes place either in the column direction or in the row direction instead of.
  • Is the printing form the printing form of a printing form cylinder in a rotary printing press so the column direction is the printing direction and the Row direction is the longitudinal direction of the cylinder.
  • the strip-shaped laser spot can advantageously also be used to set the area coverage and thus also the tonal value levels particularly finely without changing the geometry of an optical imaging device for focusing the laser light on the color-transmitting surface.
  • the duty cycle of the semiconductor laser By changing, in particular shortening, the duty cycle of the semiconductor laser, pixels of any extension in the direction of the relative movement can be generated. In particular, pixels can be generated which have very small areas, but which then are not square, but rather strip-shaped.
  • the number of shades of gray that can be displayed results from the raster width and pixel area.
  • the rule here is that the grid cell width is equal to the reciprocal of the grid width. The area of the grid cell is calculated from this by squaring.
  • the number of maximum tonal values that can be displayed is obtained.
  • a grid cell with a 40 grid has an area of 250 * 250 ⁇ m 2 .
  • a maximum of 16 gray levels can be displayed in the case of square pixels.
  • rectangular pixels of 62 ⁇ m * 31 ⁇ m are generated, there are already 32 gray levels.
  • the imaging time is the same in both cases.
  • the finer gradation of the tone levels makes it possible to better compensate for nonlinearities occurring in the print, such as tone value increases and decreases, than is possible with laser spots which do not have the very short extension according to the invention in the direction of the relative movement.
  • an angle sensor for the printing form cylinder or an associated blanket cylinder has a correspondingly higher resolution, or intermediate increments are formed with electronics by interpolation.
  • the image transmission device preferably comprises an array or several arrays of pulsed or current-pumped semiconductor lasers, in particular pulsed infrared lasers, particularly preferably laser diodes.
  • semiconductor laser narrow, Strip-shaped, preferably rectangular laser spots on the surface to be imaged generated, each on the surface to be imaged in the direction of the relative movement have measured laser spot width that is several times smaller than one in the same direction measured width of an image pixel of the surface to be imaged and is also several times smaller than a laser spot length measured across the laser spot width.
  • a pulse duration per laser spot is then several times longer than a time period in which Relative movement between the printing form and the laser array covered a distance that corresponds to the laser spot width.
  • the imaging takes place directly on the machine Printing form cylinder.
  • the relative movement between the printing form and the laser array by vertical movement by rotating the printing form cylinder and a horizontal movement perpendicular thereto by shifting the laser diode array causes.
  • the image information transferred column by column to the printing form.
  • By moving the laser array horizontally adjacent columns are imaged one after the other until the entire image is recorded is.
  • Using the laser on the ink-transferring surface of the printing form generated laser spots then have a width measured in the vertical direction and a length measured in the horizontal direction.
  • the horizontal movement takes place during the imaging of the laser array with the printing forme cylinder rotating, preferably continuously. In this way, optimally short imaging times can be obtained.
  • the resolution of the image transmission device depends on the distance by which the laser array is shifted during one cylinder revolution. This distance is preferably between 84 and 28 microns. This corresponds to a preferred resolution from 300 to 900 dpi.
  • the laser spot length is preferably 30 to 90 microns, and
  • the laser spot width is preferably 1 to 10 ⁇ m.
  • the laser pulse duration is between 1 and 50 ⁇ s, depending on the resolution of the device, the power of the laser and the imaging speed.
  • the imaging is done by axially shifting the at least one array along the printing form cylinder rotating during the imaging.
  • the total laser array can be replaced by exchangeable modules with, for example, 64 diodes per Pressure zone are formed.
  • the ratio of the laser spot length to the laser spot width is preferably at least 10: 1 and particularly preferably at least 20: 1.
  • An advantage of the image transmission device according to the invention is that a mechanical exact adjustment is not required. It will preferably be a software adjustment performed.
  • the image transmission device preferably comprises an array or several arrays For example, 256 semiconductor lasers in 4 arrays, each with 64 lasers for a printing zone.
  • Semiconductor lasers are used to produce a narrow, strip-shaped laser spot narrow, strip-shaped, preferably rectangular, light-emitting surfaces used as infrared laser diodes in particular.
  • the emitted laser light is transferred to the ink-transferring surface via an optical imaging device focused. Because of the preferred elongated strip shape of the laser spot enabled the use of simple optics in conjunction with the corresponding narrow strip shape of the light emitting surfaces and the long pulse duration per
  • the laser power can be kept low. The energy consumption is despite the longer pulse duration is also lower than when the laser spot is formed directly in or approximately in the form of the image pixel on the color transfer surface print image to be generated.
  • the image transmission device comprises pulsed or current-pumped Semiconductor laser, in particular infrared laser, particularly preferably infrared laser diodes light-emitting, strip-shaped surfaces, one in the direction of relative movement have measured width that is several times smaller than one in the same direction measured width of an image pixel on the surface to be imaged and also several times is smaller than a length of the light emitting surface.
  • infrared laser particularly preferably infrared laser diodes light-emitting, strip-shaped surfaces
  • the lasers preferably emit in the infrared or visible range, especially in the Wavelength range from 700-1400 nm.
  • FIG. 1 shows a printing material web B between two blanket cylinders 1 passed and in the formed between the two blanket cylinders 1 Printing gap printed on both sides.
  • the two blanket cylinders 1 each have a printing form cylinder 2 in the manner shown for the left blanket cylinder 1 assigned.
  • An inking roller 3 for the left blanket cylinder 1 is also shown.
  • the arrangement of cylinders and rollers is mirror-symmetrical on both sides of web B. The arrangement shown in FIG. 1 is preferably repeated for each of the many Blanket cylinder of the printing machine.
  • the machine is a newspaper offset web-fed rotary printing press with rubber-rubber production, for example a WIFAG OF 370.
  • the machine can also be a machine for rubber-steel production act, for example with one or two central steel cylinders and thus blanket cylinders forming printing gaps per printing unit, for example one WIFAG OF 470 or OF 790.
  • the ink is transferred from the inking roller 3 to the printing form cylinder 2 and from the Transfer form cylinder 2 to the blanket cylinder 1, which in the printing nip Lane B is printed with the image obtained from printing form cylinder 2.
  • the printing form cylinder 2 has a hollow cylindrical carrier cylinder 10 with a central, axial cavity 4, which is in fluid communication with a dampening solution supply device stands.
  • the fluid connection is made by a rotary connection on one or two shaft journals of the plate cylinder 2 are formed.
  • the dampening solution is supplied through this shaft journal into the cavity 4.
  • the dampening solution is previously filtered to avoid annoying deposits within a printing form 12.
  • the Carrier cylinder 10 has through channels 5 in the radial direction.
  • the through channels 5 are designed as straight, exactly radial bores 5.
  • each of the bores 5 has a diameter of 6 mm.
  • the holes 5 open on an outer jacket of the carrier cylinder 10 at a distance of 20 mm from one another, measured between the centers of the holes.
  • the outer jacket of the carrier cylinder 10 is of shell-like, surrounded perforated steel sheets.
  • the steel sheets form a perforated one Printing form support 13 of the printing form 12 permanently connected to the support cylinder 10.
  • the lower layer 14 could also directly on the carrier cylinder be attached.
  • an underlayer 14 is on the printing form support 13 bonded, which in turn serves as a support for a printing layer 15.
  • the print layer 15 forms the ink-transferring surface of the printing form cylinder on its free outer surface 2.
  • the printing layer 15 and the underlayer 14 are porous.
  • Dampening solution is injected into the cavity 4 of the printing form cylinder 2. Because of centrifugal force is the dampening solution through the holes 5 of the support cylinder 10 and the perforated printing plate carrier 13 acting as a distributor to the rear of the Underlayer 14 performed. This passes through the lower layer 14 and the printing layer 15 Dampening solution on the ink-transferring surface and causes that on the wetted Make no ink is accepted.
  • Water is used as the dampening solution, with the additives commonly used in offset printing is provided.
  • An image transmission device 20 is assigned to the printing form cylinder 2.
  • the Image transmission device 20 comprises infrared laser diodes which are applied to the surface of the Printing form cylinder 2 are directed.
  • the image transmission device is arranged that the printing form cylinder 2 rotates shortly before reaching the Contact point with the ink roller 3 sweeps the image transfer device 20.
  • the printing form cylinder 2 is assigned a washing device 30, which in the Embodiment seen in the direction of rotation behind the blanket cylinder 1 and is arranged in front of the image transmission device 20.
  • the washing device 30 ink can be washed off the surface of the printing form cylinder 2.
  • Fig. 2 shows the printing form cylinder 2 in cross section with two printing forms 12, the formed independently and with a carrier cylinder 10 of the printing form cylinder 2 are releasably attached by means of a conventional clamping device 6.
  • the carrier cylinder 10 corresponds essentially to the carrier cylinder 10 of the first Embodiment. However, the central axial feed channel or cavity 4 is included equipped with a much smaller diameter. Accordingly, they are radial branching channels 5 longer than those of the first embodiment. The radial distribution channels 5 open into axial distribution channels on the outer surface of the carrier cylinder 10 are excluded to the distribution of the dampening solution to equalize as early as possible.
  • One of the two printing forms 12 of the second exemplary embodiment is individual in FIG. 3 shown.
  • the printing form 12 is described in the first exemplary embodiment Kind by a perforated printing form carrier 13, an applied thereon Porous underlayer 14 and a porous printing layer 15 layered over it.
  • the printing form carrier 13 is made more uniform by a single semi-cylindrical steel plate Perforation formed.
  • the dampening medium flow rate of the printing form 12, based on the unimaged state, has a value which is in the range of 2-20 l / (hm 2 mbar). In an approximation which is sufficient for practical use, it also corresponds to the value of the flow through the printing layer 15.
  • the dampening solution In order to achieve a flow, the dampening solution must be supplied with a pressure that overcomes the flow resistance of the individual layers, in particular the capillary pressure of the fine-pored printing layer 15. This pressure is created by the Centrifugal forces that act on the dampening solution during the rotation of the printing form cylinder 2.
  • the pressure differential grows roughly linearly with the water level that is at the back the printing form, i.e. in a good practical approximation on the back of the print layer 15 sets.
  • the maximum Differential pressure across printing plate 12 should not exceed 100 mbar. Because with diminished Machine speed correspondingly less dampening solution on the ink-transferring Surface must and should be present, the pressure can decrease the cylinder speed, especially linear, decrease with the speed.
  • the dampening solution level on the back of the printing layer 15 may be the thickness of the underlying layer Do not exceed layers. It should be in the exemplary three-layer Printing form 12 at most as high as the thickness of the underlayer 14.
  • the dampening solution level of 3 mm results for the assumed cylinder radius of 200 mm at a rotational speed of 5,000 revolutions / h a differential pressure of about 0.45 mbar at the back of the printing layer 15.
  • This overpressure which is caused by the Pressure layer 15 is reduced, should be above the pressure difference for a sufficient flow through the pressure layer 15 is required.
  • the print layer 15 Accordingly, it should have a material structure that is at least reflected in the the thickness of the underlayer 14 resulting maximum differential pressure to the sufficient Supply of the ink-transferring surface with dampening solution is sufficient, so that also with low rotation speed printing is possible.
  • the image transmission device 20 preferably facing the lower region of the printing form cylinder 2 arranged. This provides precise imaging of the printing form 12 down to the bottom Possible speed range of the cylinder. A lower limit for the cylinder speed in the case of imaging, the newspaper offset with two printing forms has 12 per printing form cylinder 2 approximately at 3,000 U / h.
  • the image transmission device evaporates 20 the dampening solution on the surface.
  • the dampening solution wetting the surfaces becomes the corresponding printing form of the image to be transferred to the blanket cylinder 1 by means of the image transfer device 20 evaporated.
  • the dried area passes the inking roller 3 and takes color. A pore that opens into the just dried surface area is closed by the color assumed in this area, so that no Dampening solution more reaches the now printing mouth area.
  • the inking roller 3 Since after drying on the ink-transferring surface the printing layer 15 has a high temperature at the dried areas, these areas cannot be moistened immediately because the dampening solution which flows in only at a low rate evaporates immediately upon contact with the heated area of the printing layer 15 . In order that the drying of the dried area before contact with the inking roller 3 is particularly reliably prevented, the inking roller 3 is arranged immediately after the exposure device 20. The dampening solution pressure on the back of the printing layer 15 should also be set such that the dampening solution layer is formed only slowly on the ink-transferring surface. In the example above, if the inking roller 3 is 200 mm behind the exposure device 20, as seen in the direction of rotation of the printing form cylinder 2, the time period from drying to pore closure is 0.06 s.
  • the dampening solution supply on the back of the printing form 12 is set in such a way that no more than 0.5 g dampening solution per m 2 of the ink-transferring surface and rotation are supplied. Since the dampening solution film splits on the inking roller 3 with every revolution and half of it is removed, a constant film layer thickness of 1 ⁇ m in front of the inking roller 3 and 0.5 ⁇ m behind the inking roller 3 is then established. With increasing imaging time, the dampening solution supply is reduced in accordance with the area coverage already achieved. Starting with water as a dampening solution and a dampening solution layer thickness of 1 ⁇ m which is to be evaporated, imaging of the printing form cylinder 2, ie of two printing formes 12, is possible in about one minute. The power requirement of the exposure device 20 is very low due to the very thin dampening solution layer in the process alternative in which dampening solution is previously evaporated to close the pores.
  • Per printing form cylinder 2 i.e. per exposure device 20, is a control electronics intended to generate constant current pulses, the duration of the exposure time for a pixel corresponds to for each of the 265 diodes. The current strength depends on the used Laser diode between 1 and 4 A.
  • the control electronics also includes its own Bitmap memory with its own memory area assigned to each diode. Also includes the control electronics an addressing system for transferring the bits from the bitmap memory to the diodes. The address for the memory is made up of signals from one Angle of rotation of the printing form cylinder 2 or the blanket cylinder 1 and one Weggebers determined the horizontal displacement of the laser array in which the concerned Diode is arranged, measures or the motor for generating the horizontal movement pretends.
  • the imaging takes place by axial displacement of the Laser arrays along the rotating printing form cylinder 2.
  • the speed of the Horizontal displacement is considerably less than the cylinder speed at the Illustration.
  • all laser arrays are simultaneously, preferably by the same motor, axially shifted.
  • a axial feed of the exposure device 20 which is slightly smaller than the width Bs of the laser spots 28.
  • Axially adjacent pixels therefore slightly overlap. Thereby the adjacent columns of the printed image are illustrated one after the other without that blank areas remain between the columns.
  • the width of the overlap of neighboring pixels depends on the sharpness of the image of the individual pixel. Blurring in the optical image and heat diffusion in the vicinity of the pixel lead to exposure blur caused by the overlay in the imaging is balanced.
  • the laser diodes 23 are roughly mechanically adjusted as a row of diodes in the housing 21 attached. Through the array of lenses 25, the light-emitting surfaces 24 of the Laser diodes 23 imaged on the printing form 12. Due to the mechanical rough adjustment of the laser diodes 23 ensures that the geometric deviation of the laser spots 28 a certain maximum deviation on the ink-transferring surface of the printing form 12 of target positions. A fine adjustment is made in the way a software adjustment.
  • FIG. 7 shows an exposure device that corresponds to the exposure device of FIG. 5 and 6 are completely identical except for the optical imaging device.
  • the Optical imaging device of the exposure device of Figure 7 is for each of the light-emitting surfaces 24 are formed by two plane-convex lenses 25a and 25b.
  • the curved surfaces of the lenses 25a and 25b face each other, so that the plane surfaces of the lenses 25a and 25b are those surfaces through which the laser light from the light emitting surfaces 24 enters and through which it towards the color-transmitting surface of the printing layer 15 out of the optical imaging device exit.
  • the focal lengths of the lenses 25 and 25a and 25b of the optical imaging devices Figures 5 to 7 are preferably the same for both directions. This is through the narrow strip shape of the light-emitting surfaces 24 allows.
  • FIG. 7 shows the manufacturing costs through the use of the same lenses 25a and 25b kept low. In particular, plan-convex lenses are cheaper than Lenses that need to be ground on both sides.
  • the lenses 25a and 25b can can advantageously be obtained by two plastic lens arrays, as in FIG. 7 shown are arranged to each other in lens holders 29a and 29b.
  • FIG. 8 the software adjustment for a number of ones arranged side by side on a line is shown Laser diodes 23 of a laser array shown.
  • the lines entered in the upper part of FIG. 8 run in the longitudinal direction of the cylinder. Along the top line, the target positions P of the laser spots 28 are together with the actual positions S resulting from the mechanical rough adjustment of the same Laser spots 28 drawn.
  • the same line is drawn again immediately below.
  • the error vector V is entered for each of the laser diodes 23.
  • Each of the error vectors V results as a straight connecting line between the target position P and the measured one Actual position S for each of the laser diodes 23.
  • the error vectors V each become one of the associated target position P outgoing correction vector C of the same length and opposite direction. Only the correction vector is shown in FIG C for the left laser diode 23 of the laser array in FIG. 8.
  • the formation of the Correction vectors C for the other of the laser diodes 23 are made accordingly.
  • the third Line is entered per laser diode 23, the displacement X by which the laser array shifted in the longitudinal direction of the cylinder when imaging the printing form cylinder 2 becomes.
  • This shift can be gradual after completing one Cylinder rotation take place or, which is preferred, continuously during the total imaging time of the printing form cylinder 2.
  • the displacement X is slight longer than the distance between the actual positions measured in the longitudinal direction of the cylinder P from adjacent laser diodes 23.
  • Each of the laser diodes 23 is assigned an image area Ac which extends in the circumferential direction of the printing form cylinder 2 corresponding image strips. The lengthways of the printing form cylinder 2 measured length of this assigned image area Ac corresponds to the target distance between two adjacent laser diodes 23.
  • Each of the A data memory in the control electronics is assigned to laser diodes 23. This Memory is larger than the image area Ac to be transferred. It includes the so-called Imaging area A, each in the longitudinal and circumferential direction of the printing form cylinder 2 is greater than the maximum error tolerance for the mechanical rough adjustment Image area Ac. If a laser diode 23 has an exact match of the actual position S. of the laser spot 28 generated by it, the image data of the memory for this Transfer laser diode 23 into the data memory for imaging.
  • the length measured in the cylinder longitudinal direction corresponds to each of the exposure areas A.
  • the cylinder circumferential direction measured width corresponds to the cylinder circumference plus the maximum permissible Deviation due to the mechanical rough adjustment.
EP00810209A 1999-03-17 2000-03-13 Production d'une image sur une plaque d'impression pour l'impression offset humide Withdrawn EP1036655A1 (fr)

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DE19911906 1999-03-17
DE19911906A DE19911906A1 (de) 1999-03-17 1999-03-17 Bebilderung einer Druckform für einen Nassoffsetdruck

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DE102007005815A1 (de) 2007-02-06 2008-08-07 Maschinenfabrik Wifag Bebilderung einer Offset-Druckform
EP2090429A1 (fr) 2008-02-13 2009-08-19 WIFAG Maschinenfabrik AG Marquage d'une paque d'impression offset
WO2010017068A2 (fr) * 2008-08-06 2010-02-11 Nova Write Corp. Impression lithographique sans plaque
CN103009783A (zh) * 2011-08-05 2013-04-03 帕洛阿尔托研究中心公司 用于施加多组分图像的可变数据平版印刷系统及其系统
US8798104B2 (en) 2009-10-13 2014-08-05 Nanda Nathan Pulsed high-power laser apparatus and methods
US8807029B2 (en) 2008-08-06 2014-08-19 Thomas E. Lewis Plateless lithographic printing

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DE102004018118A1 (de) * 2004-04-08 2005-10-27 Axaron Bioscience Ag Nasschemische Erzeugung strukturierter dünner organischer Filme
JP4580830B2 (ja) * 2005-07-08 2010-11-17 株式会社日立製作所 画像形成方法及びそれを用いた画像形成装置
CA2643249A1 (fr) 2006-02-21 2007-08-30 Moore Wallace North America, Inc. Systemes et procedes d'impression variable haute vitesse
US8869698B2 (en) * 2007-02-21 2014-10-28 R.R. Donnelley & Sons Company Method and apparatus for transferring a principal substance
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DE102007005815A1 (de) 2007-02-06 2008-08-07 Maschinenfabrik Wifag Bebilderung einer Offset-Druckform
EP2090429A1 (fr) 2008-02-13 2009-08-19 WIFAG Maschinenfabrik AG Marquage d'une paque d'impression offset
WO2010017068A2 (fr) * 2008-08-06 2010-02-11 Nova Write Corp. Impression lithographique sans plaque
WO2010017068A3 (fr) * 2008-08-06 2010-04-22 Nova Write Corp. Impression lithographique sans plaque
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US8807029B2 (en) 2008-08-06 2014-08-19 Thomas E. Lewis Plateless lithographic printing
US8798104B2 (en) 2009-10-13 2014-08-05 Nanda Nathan Pulsed high-power laser apparatus and methods
CN103009783A (zh) * 2011-08-05 2013-04-03 帕洛阿尔托研究中心公司 用于施加多组分图像的可变数据平版印刷系统及其系统
CN103009783B (zh) * 2011-08-05 2016-03-09 帕洛阿尔托研究中心公司 用于可变数据平版印刷系统的标记材料子系统

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