CA2225304A1 - Method and apparatus for producing a printing image distribution - Google Patents
Method and apparatus for producing a printing image distribution Download PDFInfo
- Publication number
- CA2225304A1 CA2225304A1 CA002225304A CA2225304A CA2225304A1 CA 2225304 A1 CA2225304 A1 CA 2225304A1 CA 002225304 A CA002225304 A CA 002225304A CA 2225304 A CA2225304 A CA 2225304A CA 2225304 A1 CA2225304 A1 CA 2225304A1
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- Prior art keywords
- temperature
- limiting
- image
- image point
- thermally
- 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.)
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/435—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material
- B41J2/475—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material for heating selectively by radiation or ultrasonic waves
- B41J2/4753—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material for heating selectively by radiation or ultrasonic waves using thermosensitive substrates, e.g. paper
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- 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
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- 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
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- 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
- B41C1/1016—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 characterised by structural details, e.g. protective layers, backcoat layers or several imaging layers
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- 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
- B41C1/1025—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 using materials comprising a polymeric matrix containing a polymeric particulate material, e.g. hydrophobic heat coalescing particles
Abstract
A method and apparatus is disclosed for setting a distribution of image points on a printing surface having a coating of thermally activated material. For each image point to be set and used as part of an image, a laser heats the image point for a predetermined time period to a limiting or process temperature. The image points are preheated to an intermediate temperature below the limiting or process temperature and above an ambient temperature in order to reduce the energy required to raise the temperature of the thermally activated material at an image point to be set.
In one embodiment of the invention, the entire printing surface is preheated to the intermediate temperature. In an alternative embodiment of the invention, only a region of the region surface is preheated. In this alternative embodiment the region moves with a writing head that sets the image points. In this regard, the rate of travel of the image head across the printing surface is such that a temporal stationary temperature is reached at the intermediate temperature prior to raising the temperature to the limiting or process temperature.
In one embodiment of the invention, the entire printing surface is preheated to the intermediate temperature. In an alternative embodiment of the invention, only a region of the region surface is preheated. In this alternative embodiment the region moves with a writing head that sets the image points. In this regard, the rate of travel of the image head across the printing surface is such that a temporal stationary temperature is reached at the intermediate temperature prior to raising the temperature to the limiting or process temperature.
Description
METHOD AND APPARATUS FOR PRODUCING A
PRINTING IMAGE DISTRIBUTION
TECHNICAL FIELD
The invention relates to a method for producing an image on a printing plate and, more particularly, to prod~lc.inp. such an image in a layer ofthe plate comprisin~ therrn~lly activatable m~tPri~
BACKGROUND OF THE INVENTION
During the prod~Gti~)n of p.;,.l;~g forms, the pfinting and non-g surface parts must be st~uctured in accordance with the inform~tion to be printed Thus, it is known to convert therrn~lly ch~n~e~ble coating applied to a base m~t~ri~l into oleophilic, ink-accepting parts by he~ting the cOali~g using snit~ble means such as a laser beam.
15 The thprm~lly çh~ngeable coating m~tPri~l has hydrophilic properties.
r~ Li.lg forms work with a printing unit and can be of several types.
For eY~mr)le, the forms can be plates clamped onto a cylinder, which are commonly used for off-set printing ~ltern~tively, they can be films in a special prin*ng form image printing device or a sllrf~r,e of a m~r.hine 20 cylinder. In a flat bed lJ~ method using direct image 1~ e, a laser is commonly used to write onto the printing forms. As a result of the input of heat by means of the laser, a therm~lly activatable coating on the forms has hydrophilic p~ Lies. It is converted or tr~nsformed from a hydrophilic state to an oleophilic, ink-~ccepting state in response to heat 25 generated by applic~tion of the laser light to a spot-sized area (herein~ftPr the "image point").
The temperature applied to an image point ~n the therm~lly activatable coating of a form must exceed a specific threshold value. This means that the energy applied to the co~ting by the laser must locally 30 exceed a threshold value, which in tu~n generates thPrrn~l heat that raises the temperature of the image point above an "image setting temperature."
This "image setting temperature" (e.g., 280 ~) must be exceede~l for a predefined period of time such as one to two microseconds. The image point is not set if this temperature versus time ch~racteristic is not 35 observed. This l~ )e,~ c versus time char~ct~ri~tic is pre~lçfined and orient~l to the çh~nic~l and physical ~ropelLies of the th.~rm~lly activatable m~teri~l Writing printing forms by means of supplying heat is in this case unable to structure the s~ce with respect to the informqtion to be printed simply on the basis of a physical and/or chemir-q-l change to the coating mqtçri~ql In this context, methods for image rrinting by means of thçrmql 5 abrasion are also known in which an image is created based on a point-by-point energy input. Likewise, with a requirement that a limitin lclll~e.dwc be excee~le~l for a ...i~ .. action time, removal of the coqting mqterisl from the plate occurs, for example, by t~ ul~lion or by restructuring of the plate caused by chqnges to the plate's volume.
In all of the methods described above for using laser rqdiqtion as a source of heat energy to print images in a therm-q-lly açtivatable coating m,qteriql the ~lclial must be heated to exceed a temp~"~lwc for a predcle....i~-ed time interval. Depen~ling on the type of the image ~ -g method and on the composition of the thPrm,q11y activatable coating 15 mstçri,ql relatively high laser powers must be employed. The lasers are modlllqte~l to provide the ...i~-i...-~... time period required for he,q,tin~ each image point, which has a negative effect on the mi.x;...l.... achievable speed of writing precisely onto a large-format rrintin~ plate. In the case of this thermql image y. ;..~ g method using laser radiation, however, it is not only 20 disadvqnt-q-geous to need high laser power that has to be mo~lnlq-te~l it is also disadv~qntqgeous to require a high amount of thermql energy to be applied to the plate. The higha the lcl~l)e.~lwe necessqry to set an image in the thPrm~lly activatable coating, the greater the tempeMture dilrclcnce between each image point and the region of the plate ~ullu~m~ling the point.
25 This large therm-ql gradient introduces stresses which can, for exqmple, permqnently detach the coating and base m,q,teri,q,l or create deform~tions in at least one of these two layers of mqtloriql~ It is also possible for a specific type of thermqlly activatable coating m~teriql to have very good th~rmql writing plOpcl ies but nevertheless be conci(lçred an lm~lesirable 30 image p~;..l;i-g mqt~i,q,l becq.~l~e it requires excessively high lcllll)clalulcs that accentuate the p,~l~ms of mqtçri~l separation and/or deformation caused by thermql stresses.
SUMMARY AND OB.TECTS OF THE INVENTION
The ~lilll&l~ aim of the present invention is, therefore, to provide a method and a~ lus for producing a distributed prinhng image on a thçrmfl1ly activated ~ul~ lt; in such a way that the above-mentioned 5 disadv~nt~es are avoided and reliable stmctnring of the base and coating m~tçriflls for a p~ g pl~te or form are re~ ed The invention is based on direct im~ing processes and a device for direct im~ging using the1m~l activatedlconvertible m~tçrial i.e. l";~
plates or printin~ molds, having a co~ting that can be altered at an image 10 point by applying therm~l energy in a m~nner described hereinfl~çr.
According to the invention, the thPrm~l gradient around an image point fixed by thermfll action is red~lced by he~ting the region around the point to an intermediate temp~alule below the temperature for f~xing or setting the image point. By hPating the region ~ ullding the image point 15 to be set, the re-lnGed th~prmal gradient mitig~tes the separation and deform~tion problems that plague the prior art approaches. Preferably, the invention employs a two-stage heflting action on the mfltPri~l to be printed First, the therm~l mfltPrifll of the plate or prinhng form is prehe~ted to a lel-l~)el~ e below the process l~mp~lalule for setting or fixing an image 20 point. Second, the image is generated on a point-by-point basis by hç~ting the plate using a modnl~ted laser beam in keeping with the required lelll~)el~Lule and time profile for setting each of the image points.
The prehç~ting of the region around the image point to be set or fixed can be the entire plate or printing form. In this case, the entire 25 printing plate or printin~ form is heated and ~ ed at a le",~ alu~e below the limitin~ or process lell~ luLe envisioned for the image printing process. This preh~ting can be performed, for exflmple, by an electric he~ting device that is constructed as an oven for the plate.
In an ~ltçrnfltive approach for practicing the invention, a small 30 region immediately ~ uu~ding the image point is hç~ted This local prehçflting of the plate or printing form can also be pe.ro....ed by an electrical h~flting element~ using a fan to direct the heat to a loc~li7çd area o~ ding the image point. As an ~lt~rnfltive, howev~r, prçh~flting can be accomplished by a dispersed laser beam, which irradiates the plate or 35 printing form in an apprûp,ialely sized regiûn arûund the image point as it is being set. In this a~r~ ~,h the rate a writing head traverses the plate or form is controlled such that the lelll~ lu,e of the region stabilizes before the image point is set.
One advantage of inc~ , the local temperature around the image point being fixed is that it is not necess~-y for the entire printing plate or 5 printing form to be brought to a high le~)elalule level, w_ich has a disadvantage of overall thennal P~xpansion of the plate or form. As an allf~ e to local preheating using a widened laser beam, prPhe~ting by a lacuna with a heatin~ elP-mPnt or by an infrared radiation source would also provide suitable locali7~d he~ting to an intermediate temperature.
Other objects and advanta~s will become a~pa~ l from the following detailed dP~scriI~tion when taken in conjunction with the dlawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a exemplary and ideali7ed temperature profile for heatin~ a plate or printin~ form m~tP~ri~l in accordance with co~ iona practice;
FIG. 2 is an exemrl~ry and i~ali7ed tempe alu~c profile for heating a plate or printing form mat~Prial in accordance with one embodiment of the invention, where the entire plate or printing form is prehP~ted to an intPrmediate lelll~ e Tz;
FIG. 3 is an exemplary and ide~ ed temperature profile for he~ting a plate or ~ lling fonn m~teri~l in accordance with an ~ltern~tive embodiment of the invention, where a local region of the plate or printing form is prPhP~ted and the local region moves with the laser beam that sets or iixes the image points;
FIG. 4 is a schPm~tic represent?tion of a writing head with a laser and a thPrm~l pre-w~mi~lg device in accordance with the invention for generating both the therm~l set point and the therm~l prehe~ting of the ~wl~wlding region of a flat plate;
FIG. 5 is a schem~tic represent~tion of the writing head of FIG. 4 applied to wlili~g to a therm~l printin~ layer on a plate or form mounted to a cylinder;
FIG. 6 is a schem~tic diagram of a system for driving the writing head of FIGS. 5, incl~ldin~ a rail on which the head is mounted for f~ilit~ting the sc~nning of the head over the surface of the plate or form in conjunction and synchronization with the rotation of the cylinder;
..
FIG. 7 is a plan view of a th~rm~lly writable printing form illustrating the location of an exemplary few lines of image points in a matrix of image point c ~lid~tçs, which matrix is used as a map to locate image points to be set or _xed by the writing head;
FIG. 8 is a block diagram of a controller for the drive system and laser of the writing head as illu~ d in FIG. 6; and FIG. 9 is a high level flow diagram of the steps executed by the drive system in order to write the image points in precise loc~ti~ n~ on the th~rm~l layer by following the matrix map of FIG. 7.
0 While the invention is susceptible to various moflific~tions and ;v~ constructions, a certain illustrated embo~liment thereof is shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the speci_c form disclosed. To the conll~y, the int~ntion is to cover all 15 modi_c~tic)n~ t~rn~tive constructions and equivalents falling within the spirit and scope of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Turning now to the drawings and .ere";"g first to FIGS. 1-3, the exçmrl~ry temperature versus time profiles for a point (i.e., dot) on the 20 therm~lly writable snrf~ce of a printing plate or form (herein~flPr "plate") is set by a modnl~t~d laser which scans the plate on a line-by-line basis in a conventional m~nner as ç~p1~ined more fillly herein~fler. In this regard, a writing head tr~n~s~ g a focused laser beam onto the plate is moved line by line over the plate. In this case, the plate can be clamped on a flat 25 substrate as illustrated in FIG. 4 or it can be wlillen to when it is in place on a cylinder as illusll~led in FIG. 6.
The tempcralule versus time plot in FIG. 1 of the d ~wings illu~ s a conventional le~ elalule profile at the image point to be set or fixed. The image point is the exclusive region of the plate that is subjected 30 to heat. The heat from the laser raises the temperature of the image point from an ambient leml)elalu,e Tp to the temperature of the limiting or process temperature TG in accordance with the lellll)c;,~ e profile in FIGURE 1. Depending on the relative speed of the movement between the writing head and the plate, the thPrm~lly activatable m~teri~l is heated to a 35 temperature above the limitin~ or process temperature TG for a time interval ~T. After the laser beam has moved away from the image point, the L~ e~ c of the th~m~lly act,ivatable m~tçn~1 drops once more to the ambient temperature Tp as su~ested in the tPrmin~1 portion of the profile in FIGURE l.
The limitin~ or process lel~ e TG is exceeded for a predefined 5 ,.,;..;..,~.. time interval ~T, wherein both the temperature and time intervaldepend on the particular composition of the therm~1 act,ivatable coating material of the plate or form. Only when t,he lel"~e~ c TG is exceeded for the pre~fined ...;~ .. time interval ~T does a perm~nçnt physical andlor çhemi~.~1 conversion of the th~,rm~lly activat,able plate or form occur. Thus, the speed of the writing head must be cont,rolled accordingly.
In accordance with the invention, FIG. 2 illust,rates a temperat,ure versus time plot in which the entire plate is prehe~ted by a hç~tin~ device from the ambient temperature Tp to an intçrrnediate lellll)elalulc Tz, which is below the 1imiting or process lelll~el~ c TG. When the writing head is moved over the surface of the plate, the therm~11y act,ivatable layer is heated to a temperature above the 1imiting or process lel.l~elalu,e TG for the predefined time interval ~T, in subsPnti~11y the same way as described above in connect,ion with FIGURE l. However, the starting temperat,ure is now the intçrmediate le~ e.~ c Tz. Consequently, a lesser amount of heat is required to further raise the temperature of the point to the 1imiting or process temperature TG. Bec~n~e less of a temperature rise is necessary to i;x or set the image point, a lesser amount of laser power is required to be applied at the plate.
In cont,rast to the red~1ced power requirements of the invention as illustrated in FIG. 2, the convtq.ntion~1 he~tin~ profile in FIGURE 1 requires the laser beam to provide sufficient power to the image point so as to raise the temperature an addit,ional amount Tz minus Tp, which often causes def~rm~tion or layer separation as described above in the foregoiLIg "Background" section.
The exPmr1~ry le~ )elalulc profile of FIG. 3 illustrates an z~1tçrn~tive embodiment of the invention wherein the image point is prehç~tçd only for a time i_mediately precedin3~ the he~tinf~ of the point to the limitin~ or process l~ cralule TG. In this ~lt~.fn~tive embo-liment, the advantages of preh~ting are re~ ed while prehe~ting only the image point and an area imme~ tely around the image point for a time period related to the time period required to fix or set the point rather than the much longer time period for setting the points for the entire plate.
In this ~ltçrnstive embodimçnt of the invention, provision is made for the speed of movement of the writing head Co~ g the laser device 5 to be m~tched to the heating power of the prehe~tin~ system in such a way that a temp-_,ulwc state results which is steady over time with respect to the intermediate ~ ~alwc Tz. Then, as in the P~empl~ry embodiment according to FIG. 2, the therm~lly activatable m~tçri~l of the plate is brought to a temperature above the limiting process temperature TG
10 according to the envisio~ed ~ .. action time ~T by means of the mod~ ted laser beam. After the image point has been set, the heat sir~te~ and the lel-l~c;ldtwe cools to the intçrmediate temperature Tz.
The point will stabilize at the intermediate lelllpel~lwc Tz until the region~l he~tin~ of the plate no longer incl~ldes the area around the set or 15 fixed point. Thus, the t,~ c;lalwc will pl~te~ll at the intermediate tempelalwc Tz until the printing head moves farther away, which results in the region of prehe~ting moving off the set image point and, therefore, the le~ )elutw~ retums to the ambient temperature Tp.
As can be seen from the fo~cgoiug description, there is provided a 20 method and ap~alus for prehç~ting th~rm~lly writable y~ plates or forms, which enables the amount of laser power applied to set image points to be lessened with respect to the methods of the prior art. By applying a redllced amount of laser power to write onto the plate, the problems of deformation or layer separation are dramatically reduced, which results in 25 higher quality p.i~ g plates that in turn provide higher quality prints.
FIG. 4 illu~llal~s a laser 2 focused on an image point 4 of a plate. In kçeping with the invention, a prehe~tin~ device 6 such as an i~cd radiator or a hot air blower pl~hcd~ an area or zone S ~wl- ullding the image point 4. The laser 2 is of a collv~nLional construction for producing 30 a modnl~ted laser beam 3. The preh~tin~ device can be also of convçntion~l design for producing a directed beam of infrared r~ tion 7 or simply generating an air flow of heated air directed to the region 5.
In FIG. 4, the printin~ plate is in a planar configuration. In a conventional m~nn~r, the laser 2 and prçhe~t ng device 6 are mounted 35 togetller in a writing head, which in turn is mounted to a drive system for increm~ont~lly moving the writing head to discrete image points on the plates that form an array. By he~tin~ selective ones of the image points in the array, the writing head forms an image on the therm~lly actn~t~ble surface of the plate In a collv~ ;on~l m~nner, writing head moves increment~lly along a rail (not shown) for Il~V~l~g the plates. A second 5 rail (also not shown) increments the transverse rail from the top to bottom of the plate so that the writing head scans the entire plate and is positionable over each of the available image points on the plate .
As an ~ltern~tive to printing on a flat plate as illustrated in FIG. 4, the invention also co~ ...pl~tes writing in a convention~l m~nner on a plate 10 mounted to a printing cylinder 13 as illustrated in FII~r. 5. The three cylinders 13, 15 and 17 illustrated in FIG. 5 are collv~nlional cylinders in a printing unit for off-set printing of a p~ g sheet 19. In this regard, the P~ e sheet 19 is directed into a nip formed between a counter-pl~s~ule cylinder 17 and a rubber blanket cylinder 15. The image printed onto the 15 l..;..l;..g sheet 19, is ~ressed onto the rubber blanket cylinder 15 by the plate cylinder 13 in a conv~ntion~1 m~nner As illustrated in FIG. 5, the writing head 21 for pe.ro....ill~ the method ofthe invention is mounted to an a~yal~lus for coor~lin~ting the transverse movement of the writing head 21 along the length of the cylinder 13 and coor 1in~tin that movement with the rot~tion~l movement of the cylinder.
The mech~nicm for controlling the movement of the writing head 21 and coor~lil-~l;,-g that movement with the rotational movement of the cylinder 13 is illustrated in FIG. 6. The writing head 21 is mounted for reciprocating movement on a rail 23 that m~int~in~ the writing head in proper ~lignmpnt with the therm~lly writable printing form 11 on the cylinder 13 for setting image points. A system drive 24 controls the reciprocating movement of the writing head 21 on the rail 23 in a m~nner such that the writing head moves in increments from one end of the cylinder to the other. As su~ested by the illustration of the printin~ form 11 in FIG. 7, the cylinder 13 in FIG. 6 is held static by a rotational drive 25 while the writing head 21 is moved along the rail 23 from one end of the cylinder to the other in order to set selected ones of the image points 4, which create a distribution of the set points that form an image when viewed as a composite. Rotational drive 25 may be a motor such as a stepper motor whose step resolution complement~ the ~mll~rily of ~he image points as suggested by their spacing in the illustration of FIG. 7. In this regard, one transverse pass of the writing head 21 allows the head to set selected ones of the image points 4, in a line of an array of points as illustrated in FIG. 7.
In order to increment the writing head 21 to the next line, a drive 27 5 for the cylinder 13 in FIG. 6 rotates the cylinder by an incrPmPnt~l amount that rotates the therm~lly writable printing form 11 mounted to the cylinder by an amount that aligns an ~dj~cent line of image points with the writing head. Like the drive 25, the drive 27 may be a motor such as a stepper motor whose step resolution comrlPment~ the gr~mll~rity of the lines as 10 sll~ested by the sp~cing of the lines in the illustration of FIG. 7. The cylinder 13 is mounted for rotation on support structures 28A and 28B.
The cylinder 13 is mounted for rotation on a shaft 30, which is driven by the drive 27.
In a conventional manner, the drive system 24 for the drives 25 and 15 27 coordinates the rot~tionn1 movement of the cylinder 13 and the reciprocating movement of the writing head 21 on the rail 23. Also, the drive system provides control signal to the laser 2, c~l1sing it to modulate its laser beam so as to set only those image points 4 desired to create the overall image to be printed on the p~ g sheet 19. The haldw~e of the 20 drive system 24 is shown in FIG. 8 and the methodology executed by the hal.lw~uc for sc~nnin~ the printing form 11 in a line-by-line basis is illu~ led in a flow diagram in FIG. 9.
The drive system 24 inchldes a microcontroller 31 as illustrated in FIG. 8, which is in ch.. l~.ications with a memory 33 that contains a file 25 of the image. The image file is form~t~ed to complementc the physical matrix format of the image points 4 placed on the form 11. In this regard, the file of the image can be a simple matrix itself' with each cell corresponding to one of the image points. Each cell can inclnde a data field that is illlel~leled by the micro controller for the purpose of providing 30 an a~plopliate control signal for mod~ ting the laser to set selected ones of the points. The microcontroller 31 also is in co.~ ic~tion~ with a program memory 35, which contains executable files for controlling the movement of the drives 25 and 27 and the laser 2 In a convention~l m~nner, an int~ ce 37 co.~.~..l.l-ic~tes control signals from the 35 microcontroller 31 to ~he drives 25 and 27 and the laser 2.
Turning to the flow diagram of FIG. 9, the drive system 24 scans the image points 4 in a lc~ ive m~nner, be~innin~ with a first point in the matrix of image points (see FIG. 7) to the last point in the m~trix Starting at step 41, the microcontroller 31 reads the image points to be set from the 5 point distribution memory 33. Pursuant to the program memory 35, the microcontroller 31 executes the rem~ining steps in the flow diagram of FIG. 9 in a recursive m~nner.
Specifically, the microcontroller 31 sets the drives 25 and 27 such that the writing head 21 is initially align~l with the _rst line and _rst point 10 in that line at steps 43 and 45, respectively. Pursuant to the program in memory 35, the _rst line is thclc~lcl scanned on a point-by-point basis in steps 47, 49, 51 and 53 until the last point in the line is id~ntified in step 51. When the last image point 4 is identified in the line at step 51, the program 35 controlling the microcontroller 31 branches to step 55 to 15 del~ e whether a next line exists. If the line just scanned is the last line,the program 35 exits and releases control of the microcontroller to other operations. Otherwise, the program 35 increments to the next line by driving the driver 27 by an increm~nt~l amount at step 57. The program 35 then returns to step 45 as illustrated in the flow diagraIn of FIG. 9 and 20 repeats the steps for 45, 47, 49, 51 and 53 in a recursive m~nner. After all of the lines have been scanned and selected ones of the image points 4 have been set in keeping with the data in the point distribution memory 33, the desired image is then completely written to the form 11, which is now ready for use in an off-set prinling process as illustrated in FIG. 5.
PRINTING IMAGE DISTRIBUTION
TECHNICAL FIELD
The invention relates to a method for producing an image on a printing plate and, more particularly, to prod~lc.inp. such an image in a layer ofthe plate comprisin~ therrn~lly activatable m~tPri~
BACKGROUND OF THE INVENTION
During the prod~Gti~)n of p.;,.l;~g forms, the pfinting and non-g surface parts must be st~uctured in accordance with the inform~tion to be printed Thus, it is known to convert therrn~lly ch~n~e~ble coating applied to a base m~t~ri~l into oleophilic, ink-accepting parts by he~ting the cOali~g using snit~ble means such as a laser beam.
15 The thprm~lly çh~ngeable coating m~tPri~l has hydrophilic properties.
r~ Li.lg forms work with a printing unit and can be of several types.
For eY~mr)le, the forms can be plates clamped onto a cylinder, which are commonly used for off-set printing ~ltern~tively, they can be films in a special prin*ng form image printing device or a sllrf~r,e of a m~r.hine 20 cylinder. In a flat bed lJ~ method using direct image 1~ e, a laser is commonly used to write onto the printing forms. As a result of the input of heat by means of the laser, a therm~lly activatable coating on the forms has hydrophilic p~ Lies. It is converted or tr~nsformed from a hydrophilic state to an oleophilic, ink-~ccepting state in response to heat 25 generated by applic~tion of the laser light to a spot-sized area (herein~ftPr the "image point").
The temperature applied to an image point ~n the therm~lly activatable coating of a form must exceed a specific threshold value. This means that the energy applied to the co~ting by the laser must locally 30 exceed a threshold value, which in tu~n generates thPrrn~l heat that raises the temperature of the image point above an "image setting temperature."
This "image setting temperature" (e.g., 280 ~) must be exceede~l for a predefined period of time such as one to two microseconds. The image point is not set if this temperature versus time ch~racteristic is not 35 observed. This l~ )e,~ c versus time char~ct~ri~tic is pre~lçfined and orient~l to the çh~nic~l and physical ~ropelLies of the th.~rm~lly activatable m~teri~l Writing printing forms by means of supplying heat is in this case unable to structure the s~ce with respect to the informqtion to be printed simply on the basis of a physical and/or chemir-q-l change to the coating mqtçri~ql In this context, methods for image rrinting by means of thçrmql 5 abrasion are also known in which an image is created based on a point-by-point energy input. Likewise, with a requirement that a limitin lclll~e.dwc be excee~le~l for a ...i~ .. action time, removal of the coqting mqterisl from the plate occurs, for example, by t~ ul~lion or by restructuring of the plate caused by chqnges to the plate's volume.
In all of the methods described above for using laser rqdiqtion as a source of heat energy to print images in a therm-q-lly açtivatable coating m,qteriql the ~lclial must be heated to exceed a temp~"~lwc for a predcle....i~-ed time interval. Depen~ling on the type of the image ~ -g method and on the composition of the thPrm,q11y activatable coating 15 mstçri,ql relatively high laser powers must be employed. The lasers are modlllqte~l to provide the ...i~-i...-~... time period required for he,q,tin~ each image point, which has a negative effect on the mi.x;...l.... achievable speed of writing precisely onto a large-format rrintin~ plate. In the case of this thermql image y. ;..~ g method using laser radiation, however, it is not only 20 disadvqnt-q-geous to need high laser power that has to be mo~lnlq-te~l it is also disadv~qntqgeous to require a high amount of thermql energy to be applied to the plate. The higha the lcl~l)e.~lwe necessqry to set an image in the thPrm~lly activatable coating, the greater the tempeMture dilrclcnce between each image point and the region of the plate ~ullu~m~ling the point.
25 This large therm-ql gradient introduces stresses which can, for exqmple, permqnently detach the coating and base m,q,teri,q,l or create deform~tions in at least one of these two layers of mqtloriql~ It is also possible for a specific type of thermqlly activatable coating m~teriql to have very good th~rmql writing plOpcl ies but nevertheless be conci(lçred an lm~lesirable 30 image p~;..l;i-g mqt~i,q,l becq.~l~e it requires excessively high lcllll)clalulcs that accentuate the p,~l~ms of mqtçri~l separation and/or deformation caused by thermql stresses.
SUMMARY AND OB.TECTS OF THE INVENTION
The ~lilll&l~ aim of the present invention is, therefore, to provide a method and a~ lus for producing a distributed prinhng image on a thçrmfl1ly activated ~ul~ lt; in such a way that the above-mentioned 5 disadv~nt~es are avoided and reliable stmctnring of the base and coating m~tçriflls for a p~ g pl~te or form are re~ ed The invention is based on direct im~ing processes and a device for direct im~ging using the1m~l activatedlconvertible m~tçrial i.e. l";~
plates or printin~ molds, having a co~ting that can be altered at an image 10 point by applying therm~l energy in a m~nner described hereinfl~çr.
According to the invention, the thPrm~l gradient around an image point fixed by thermfll action is red~lced by he~ting the region around the point to an intermediate temp~alule below the temperature for f~xing or setting the image point. By hPating the region ~ ullding the image point 15 to be set, the re-lnGed th~prmal gradient mitig~tes the separation and deform~tion problems that plague the prior art approaches. Preferably, the invention employs a two-stage heflting action on the mfltPri~l to be printed First, the therm~l mfltPrifll of the plate or prinhng form is prehe~ted to a lel-l~)el~ e below the process l~mp~lalule for setting or fixing an image 20 point. Second, the image is generated on a point-by-point basis by hç~ting the plate using a modnl~ted laser beam in keeping with the required lelll~)el~Lule and time profile for setting each of the image points.
The prehç~ting of the region around the image point to be set or fixed can be the entire plate or printing form. In this case, the entire 25 printing plate or printin~ form is heated and ~ ed at a le",~ alu~e below the limitin~ or process lell~ luLe envisioned for the image printing process. This preh~ting can be performed, for exflmple, by an electric he~ting device that is constructed as an oven for the plate.
In an ~ltçrnfltive approach for practicing the invention, a small 30 region immediately ~ uu~ding the image point is hç~ted This local prehçflting of the plate or printing form can also be pe.ro....ed by an electrical h~flting element~ using a fan to direct the heat to a loc~li7çd area o~ ding the image point. As an ~lt~rnfltive, howev~r, prçh~flting can be accomplished by a dispersed laser beam, which irradiates the plate or 35 printing form in an apprûp,ialely sized regiûn arûund the image point as it is being set. In this a~r~ ~,h the rate a writing head traverses the plate or form is controlled such that the lelll~ lu,e of the region stabilizes before the image point is set.
One advantage of inc~ , the local temperature around the image point being fixed is that it is not necess~-y for the entire printing plate or 5 printing form to be brought to a high le~)elalule level, w_ich has a disadvantage of overall thennal P~xpansion of the plate or form. As an allf~ e to local preheating using a widened laser beam, prPhe~ting by a lacuna with a heatin~ elP-mPnt or by an infrared radiation source would also provide suitable locali7~d he~ting to an intermediate temperature.
Other objects and advanta~s will become a~pa~ l from the following detailed dP~scriI~tion when taken in conjunction with the dlawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a exemplary and ideali7ed temperature profile for heatin~ a plate or printin~ form m~tP~ri~l in accordance with co~ iona practice;
FIG. 2 is an exemrl~ry and i~ali7ed tempe alu~c profile for heating a plate or printing form mat~Prial in accordance with one embodiment of the invention, where the entire plate or printing form is prehP~ted to an intPrmediate lelll~ e Tz;
FIG. 3 is an exemplary and ide~ ed temperature profile for he~ting a plate or ~ lling fonn m~teri~l in accordance with an ~ltern~tive embodiment of the invention, where a local region of the plate or printing form is prPhP~ted and the local region moves with the laser beam that sets or iixes the image points;
FIG. 4 is a schPm~tic represent?tion of a writing head with a laser and a thPrm~l pre-w~mi~lg device in accordance with the invention for generating both the therm~l set point and the therm~l prehe~ting of the ~wl~wlding region of a flat plate;
FIG. 5 is a schem~tic represent~tion of the writing head of FIG. 4 applied to wlili~g to a therm~l printin~ layer on a plate or form mounted to a cylinder;
FIG. 6 is a schem~tic diagram of a system for driving the writing head of FIGS. 5, incl~ldin~ a rail on which the head is mounted for f~ilit~ting the sc~nning of the head over the surface of the plate or form in conjunction and synchronization with the rotation of the cylinder;
..
FIG. 7 is a plan view of a th~rm~lly writable printing form illustrating the location of an exemplary few lines of image points in a matrix of image point c ~lid~tçs, which matrix is used as a map to locate image points to be set or _xed by the writing head;
FIG. 8 is a block diagram of a controller for the drive system and laser of the writing head as illu~ d in FIG. 6; and FIG. 9 is a high level flow diagram of the steps executed by the drive system in order to write the image points in precise loc~ti~ n~ on the th~rm~l layer by following the matrix map of FIG. 7.
0 While the invention is susceptible to various moflific~tions and ;v~ constructions, a certain illustrated embo~liment thereof is shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the speci_c form disclosed. To the conll~y, the int~ntion is to cover all 15 modi_c~tic)n~ t~rn~tive constructions and equivalents falling within the spirit and scope of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Turning now to the drawings and .ere";"g first to FIGS. 1-3, the exçmrl~ry temperature versus time profiles for a point (i.e., dot) on the 20 therm~lly writable snrf~ce of a printing plate or form (herein~flPr "plate") is set by a modnl~t~d laser which scans the plate on a line-by-line basis in a conventional m~nner as ç~p1~ined more fillly herein~fler. In this regard, a writing head tr~n~s~ g a focused laser beam onto the plate is moved line by line over the plate. In this case, the plate can be clamped on a flat 25 substrate as illustrated in FIG. 4 or it can be wlillen to when it is in place on a cylinder as illusll~led in FIG. 6.
The tempcralule versus time plot in FIG. 1 of the d ~wings illu~ s a conventional le~ elalule profile at the image point to be set or fixed. The image point is the exclusive region of the plate that is subjected 30 to heat. The heat from the laser raises the temperature of the image point from an ambient leml)elalu,e Tp to the temperature of the limiting or process temperature TG in accordance with the lellll)c;,~ e profile in FIGURE 1. Depending on the relative speed of the movement between the writing head and the plate, the thPrm~lly activatable m~teri~l is heated to a 35 temperature above the limitin~ or process temperature TG for a time interval ~T. After the laser beam has moved away from the image point, the L~ e~ c of the th~m~lly act,ivatable m~tçn~1 drops once more to the ambient temperature Tp as su~ested in the tPrmin~1 portion of the profile in FIGURE l.
The limitin~ or process lel~ e TG is exceeded for a predefined 5 ,.,;..;..,~.. time interval ~T, wherein both the temperature and time intervaldepend on the particular composition of the therm~1 act,ivatable coating material of the plate or form. Only when t,he lel"~e~ c TG is exceeded for the pre~fined ...;~ .. time interval ~T does a perm~nçnt physical andlor çhemi~.~1 conversion of the th~,rm~lly activat,able plate or form occur. Thus, the speed of the writing head must be cont,rolled accordingly.
In accordance with the invention, FIG. 2 illust,rates a temperat,ure versus time plot in which the entire plate is prehe~ted by a hç~tin~ device from the ambient temperature Tp to an intçrrnediate lellll)elalulc Tz, which is below the 1imiting or process lelll~el~ c TG. When the writing head is moved over the surface of the plate, the therm~11y act,ivatable layer is heated to a temperature above the 1imiting or process lel.l~elalu,e TG for the predefined time interval ~T, in subsPnti~11y the same way as described above in connect,ion with FIGURE l. However, the starting temperat,ure is now the intçrmediate le~ e.~ c Tz. Consequently, a lesser amount of heat is required to further raise the temperature of the point to the 1imiting or process temperature TG. Bec~n~e less of a temperature rise is necessary to i;x or set the image point, a lesser amount of laser power is required to be applied at the plate.
In cont,rast to the red~1ced power requirements of the invention as illustrated in FIG. 2, the convtq.ntion~1 he~tin~ profile in FIGURE 1 requires the laser beam to provide sufficient power to the image point so as to raise the temperature an addit,ional amount Tz minus Tp, which often causes def~rm~tion or layer separation as described above in the foregoiLIg "Background" section.
The exPmr1~ry le~ )elalulc profile of FIG. 3 illustrates an z~1tçrn~tive embodiment of the invention wherein the image point is prehç~tçd only for a time i_mediately precedin3~ the he~tinf~ of the point to the limitin~ or process l~ cralule TG. In this ~lt~.fn~tive embo-liment, the advantages of preh~ting are re~ ed while prehe~ting only the image point and an area imme~ tely around the image point for a time period related to the time period required to fix or set the point rather than the much longer time period for setting the points for the entire plate.
In this ~ltçrnstive embodimçnt of the invention, provision is made for the speed of movement of the writing head Co~ g the laser device 5 to be m~tched to the heating power of the prehe~tin~ system in such a way that a temp-_,ulwc state results which is steady over time with respect to the intermediate ~ ~alwc Tz. Then, as in the P~empl~ry embodiment according to FIG. 2, the therm~lly activatable m~tçri~l of the plate is brought to a temperature above the limiting process temperature TG
10 according to the envisio~ed ~ .. action time ~T by means of the mod~ ted laser beam. After the image point has been set, the heat sir~te~ and the lel-l~c;ldtwe cools to the intçrmediate temperature Tz.
The point will stabilize at the intermediate lelllpel~lwc Tz until the region~l he~tin~ of the plate no longer incl~ldes the area around the set or 15 fixed point. Thus, the t,~ c;lalwc will pl~te~ll at the intermediate tempelalwc Tz until the printing head moves farther away, which results in the region of prehe~ting moving off the set image point and, therefore, the le~ )elutw~ retums to the ambient temperature Tp.
As can be seen from the fo~cgoiug description, there is provided a 20 method and ap~alus for prehç~ting th~rm~lly writable y~ plates or forms, which enables the amount of laser power applied to set image points to be lessened with respect to the methods of the prior art. By applying a redllced amount of laser power to write onto the plate, the problems of deformation or layer separation are dramatically reduced, which results in 25 higher quality p.i~ g plates that in turn provide higher quality prints.
FIG. 4 illu~llal~s a laser 2 focused on an image point 4 of a plate. In kçeping with the invention, a prehe~tin~ device 6 such as an i~cd radiator or a hot air blower pl~hcd~ an area or zone S ~wl- ullding the image point 4. The laser 2 is of a collv~nLional construction for producing 30 a modnl~ted laser beam 3. The preh~tin~ device can be also of convçntion~l design for producing a directed beam of infrared r~ tion 7 or simply generating an air flow of heated air directed to the region 5.
In FIG. 4, the printin~ plate is in a planar configuration. In a conventional m~nn~r, the laser 2 and prçhe~t ng device 6 are mounted 35 togetller in a writing head, which in turn is mounted to a drive system for increm~ont~lly moving the writing head to discrete image points on the plates that form an array. By he~tin~ selective ones of the image points in the array, the writing head forms an image on the therm~lly actn~t~ble surface of the plate In a collv~ ;on~l m~nner, writing head moves increment~lly along a rail (not shown) for Il~V~l~g the plates. A second 5 rail (also not shown) increments the transverse rail from the top to bottom of the plate so that the writing head scans the entire plate and is positionable over each of the available image points on the plate .
As an ~ltern~tive to printing on a flat plate as illustrated in FIG. 4, the invention also co~ ...pl~tes writing in a convention~l m~nner on a plate 10 mounted to a printing cylinder 13 as illustrated in FII~r. 5. The three cylinders 13, 15 and 17 illustrated in FIG. 5 are collv~nlional cylinders in a printing unit for off-set printing of a p~ g sheet 19. In this regard, the P~ e sheet 19 is directed into a nip formed between a counter-pl~s~ule cylinder 17 and a rubber blanket cylinder 15. The image printed onto the 15 l..;..l;..g sheet 19, is ~ressed onto the rubber blanket cylinder 15 by the plate cylinder 13 in a conv~ntion~1 m~nner As illustrated in FIG. 5, the writing head 21 for pe.ro....ill~ the method ofthe invention is mounted to an a~yal~lus for coor~lin~ting the transverse movement of the writing head 21 along the length of the cylinder 13 and coor 1in~tin that movement with the rot~tion~l movement of the cylinder.
The mech~nicm for controlling the movement of the writing head 21 and coor~lil-~l;,-g that movement with the rotational movement of the cylinder 13 is illustrated in FIG. 6. The writing head 21 is mounted for reciprocating movement on a rail 23 that m~int~in~ the writing head in proper ~lignmpnt with the therm~lly writable printing form 11 on the cylinder 13 for setting image points. A system drive 24 controls the reciprocating movement of the writing head 21 on the rail 23 in a m~nner such that the writing head moves in increments from one end of the cylinder to the other. As su~ested by the illustration of the printin~ form 11 in FIG. 7, the cylinder 13 in FIG. 6 is held static by a rotational drive 25 while the writing head 21 is moved along the rail 23 from one end of the cylinder to the other in order to set selected ones of the image points 4, which create a distribution of the set points that form an image when viewed as a composite. Rotational drive 25 may be a motor such as a stepper motor whose step resolution complement~ the ~mll~rily of ~he image points as suggested by their spacing in the illustration of FIG. 7. In this regard, one transverse pass of the writing head 21 allows the head to set selected ones of the image points 4, in a line of an array of points as illustrated in FIG. 7.
In order to increment the writing head 21 to the next line, a drive 27 5 for the cylinder 13 in FIG. 6 rotates the cylinder by an incrPmPnt~l amount that rotates the therm~lly writable printing form 11 mounted to the cylinder by an amount that aligns an ~dj~cent line of image points with the writing head. Like the drive 25, the drive 27 may be a motor such as a stepper motor whose step resolution comrlPment~ the gr~mll~rity of the lines as 10 sll~ested by the sp~cing of the lines in the illustration of FIG. 7. The cylinder 13 is mounted for rotation on support structures 28A and 28B.
The cylinder 13 is mounted for rotation on a shaft 30, which is driven by the drive 27.
In a conventional manner, the drive system 24 for the drives 25 and 15 27 coordinates the rot~tionn1 movement of the cylinder 13 and the reciprocating movement of the writing head 21 on the rail 23. Also, the drive system provides control signal to the laser 2, c~l1sing it to modulate its laser beam so as to set only those image points 4 desired to create the overall image to be printed on the p~ g sheet 19. The haldw~e of the 20 drive system 24 is shown in FIG. 8 and the methodology executed by the hal.lw~uc for sc~nnin~ the printing form 11 in a line-by-line basis is illu~ led in a flow diagram in FIG. 9.
The drive system 24 inchldes a microcontroller 31 as illustrated in FIG. 8, which is in ch.. l~.ications with a memory 33 that contains a file 25 of the image. The image file is form~t~ed to complementc the physical matrix format of the image points 4 placed on the form 11. In this regard, the file of the image can be a simple matrix itself' with each cell corresponding to one of the image points. Each cell can inclnde a data field that is illlel~leled by the micro controller for the purpose of providing 30 an a~plopliate control signal for mod~ ting the laser to set selected ones of the points. The microcontroller 31 also is in co.~ ic~tion~ with a program memory 35, which contains executable files for controlling the movement of the drives 25 and 27 and the laser 2 In a convention~l m~nner, an int~ ce 37 co.~.~..l.l-ic~tes control signals from the 35 microcontroller 31 to ~he drives 25 and 27 and the laser 2.
Turning to the flow diagram of FIG. 9, the drive system 24 scans the image points 4 in a lc~ ive m~nner, be~innin~ with a first point in the matrix of image points (see FIG. 7) to the last point in the m~trix Starting at step 41, the microcontroller 31 reads the image points to be set from the 5 point distribution memory 33. Pursuant to the program memory 35, the microcontroller 31 executes the rem~ining steps in the flow diagram of FIG. 9 in a recursive m~nner.
Specifically, the microcontroller 31 sets the drives 25 and 27 such that the writing head 21 is initially align~l with the _rst line and _rst point 10 in that line at steps 43 and 45, respectively. Pursuant to the program in memory 35, the _rst line is thclc~lcl scanned on a point-by-point basis in steps 47, 49, 51 and 53 until the last point in the line is id~ntified in step 51. When the last image point 4 is identified in the line at step 51, the program 35 controlling the microcontroller 31 branches to step 55 to 15 del~ e whether a next line exists. If the line just scanned is the last line,the program 35 exits and releases control of the microcontroller to other operations. Otherwise, the program 35 increments to the next line by driving the driver 27 by an increm~nt~l amount at step 57. The program 35 then returns to step 45 as illustrated in the flow diagraIn of FIG. 9 and 20 repeats the steps for 45, 47, 49, 51 and 53 in a recursive m~nner. After all of the lines have been scanned and selected ones of the image points 4 have been set in keeping with the data in the point distribution memory 33, the desired image is then completely written to the form 11, which is now ready for use in an off-set prinling process as illustrated in FIG. 5.
Claims (10)
1. A method for setting a distribution of image points on a printing surface having a coating of a thermally activated material and moving an imaging device across the surface for the purpose of setting image points, and the thermal activated material being heated locally at each image point to be set for a predetermined time period to above a limiting or process temperature that is determined by thermal characteristics of the thermally activated material the thermal activated coating being preheated, at least in an area surrounding the image point to be set, to an intermediate temperature below the limiting or process temperature of the thermally activated material, and locally heating of the image point to be set starting with this intermediate temperature, while rate of travel of the imaging device across the printing surface is such that a temporal stationary temperature is reached at the intermediate temperature prior to raising the temperature to the limiting or process temperature.
2. The method of claim 1 wherein the printing surface is heated, in a region around the image point to be set, to the intermediate temperature and below the limiting or process temperature, a size of this region situated around the image point to be set being a multiple of the extent of the image point to be set.
3. The method of claim 1 wherein the entire area of the thermally activatable material of the printing plate or printing form is heated to an intermediate temperature above the plate and printing form temperature and below the limiting or process temperature of the activatable material.
4. The method of claim 1, 2 or 3 wherein the image point by image point heating of the thermally activatable material of the printing plate or printing form is performed by means of laser radiation, the radiation power of the laser being matched to the heating of the thermally activatable material of the printing surface from the intermediate temperature to a predefined value above the limiting or process temperature of the thermally activatable material.
5. The method of claim 1, 2, 3 or 4 wherein the preheating of the thermally activatable material of the printing surface to an intermediate temperature above an ambient temperature and below the limiting, or process temperature necessitated by the material is performed by electromagnetic radiation.
6. The method of claim 5 wherein the heating of the thermally activatable material is performed by infrared radiation.
7. The method of claim 5 wherein the heating of the thermally activatable material is performed by laser radiation.
8. The method of claim 5 wherein the heating of the thermally activatable material to an intermediate temperature below the limiting or process temperature of the material is performed by a hot-gas stream directed onto the material layer.
9. The method of claim 5 wherein the heating of the thermally activatable material to an intermediate temperature below the limiting or process temperature of the material is performed by heating a body that is in thermal contact with the thermally activatable material.
10. Apparatus for setting a distribution of image points on a printing surface having a coating of a thermally activated material comprising a writing device for the image point by image point heating of the thermally activated material of the printing surface to a temperature above a limiting or process temperature of the thermally activated material, said writing device comprising means for bringing the thermal material to a temperature above the limiting or process temperature of the thermally activated material and means for preheating at least a region around the image point to be printed on to a temperature below the limiting or process temperature of the thermally activated material.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002225304A CA2225304A1 (en) | 1996-12-21 | 1997-12-19 | Method and apparatus for producing a printing image distribution |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19654018.6 | 1996-12-21 | ||
| CA002225304A CA2225304A1 (en) | 1996-12-21 | 1997-12-19 | Method and apparatus for producing a printing image distribution |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2225304A1 true CA2225304A1 (en) | 1998-06-21 |
Family
ID=4161924
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002225304A Abandoned CA2225304A1 (en) | 1996-12-21 | 1997-12-19 | Method and apparatus for producing a printing image distribution |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2225304A1 (en) |
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| WO2011114296A1 (en) * | 2010-03-18 | 2011-09-22 | Koninklijke Philips Electronics N.V. | Printing apparatus and method for controlling a printing apparatus |
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-
1997
- 1997-12-19 CA CA002225304A patent/CA2225304A1/en not_active Abandoned
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011114296A1 (en) * | 2010-03-18 | 2011-09-22 | Koninklijke Philips Electronics N.V. | Printing apparatus and method for controlling a printing apparatus |
| US9573385B2 (en) | 2010-03-18 | 2017-02-21 | Koninklijke Philips N.V. | Printing apparatus and method for controlling a printing apparatus |
| US10808786B2 (en) | 2011-10-11 | 2020-10-20 | Harrison Spinks Components Limited | Hybrid spring |
| WO2013114130A3 (en) * | 2012-02-01 | 2013-11-07 | Lumejet Holdings Limited | Media exposure device, system and method |
| US11800937B2 (en) | 2012-08-10 | 2023-10-31 | Harrison Spinks Components Limited | Resilient unit with different major surfaces |
| US11305941B2 (en) | 2017-05-31 | 2022-04-19 | HS Products Limited | Transportation apparatus and method |
| US11412860B2 (en) | 2017-05-31 | 2022-08-16 | HS Products Limited | Pocketed spring unit and method of manufacture |
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