CA2000343C - Electrostatically controllable printing form - Google Patents
Electrostatically controllable printing formInfo
- Publication number
- CA2000343C CA2000343C CA002000343A CA2000343A CA2000343C CA 2000343 C CA2000343 C CA 2000343C CA 002000343 A CA002000343 A CA 002000343A CA 2000343 A CA2000343 A CA 2000343A CA 2000343 C CA2000343 C CA 2000343C
- Authority
- CA
- Canada
- Prior art keywords
- printing
- layer
- ink
- toner
- printing form
- 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.)
- Expired - Fee Related
Links
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
- B41C1/1058—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme by providing a magnetic pattern, a ferroelectric pattern or a semiconductive pattern, e.g. by electrophotography
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
- B41N1/00—Printing plates or foils; Materials therefor
- B41N1/006—Printing plates or foils; Materials therefor made entirely of inorganic materials other than natural stone or metals, e.g. ceramics, carbide materials, ferroelectric materials
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Inorganic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Electrophotography Using Other Than Carlson'S Method (AREA)
- Printing Methods (AREA)
- Printing Plates And Materials Therefor (AREA)
- Wet Developing In Electrophotography (AREA)
- Exposure Or Original Feeding In Electrophotography (AREA)
- Color Electrophotography (AREA)
- Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
Abstract
To provide an electrically controllable printing form, on which the printing image is retained even upon repeated application of printing toner or printing ink formed of toner suspended in a carrier liquid, the printing form (10) has a surface layer (12) of ferroelectric material or, if a gravure form (40), the cells (31) have a bottom (32) of ferroelectric material. The form is programmed under control of a control unit (13, 13') by an electrode (14, 14') which selectively polarizes the ferroelectric material. Upon application of electrically charged toner or ink, the ink or toner particles which are charged oppositely to the polarization of the ferroelectric layer or bottom will be retained, the equally charged particles repelled, so that, by selective positive or negative polarization, two-color printing can be effected at one pass of a printing substrate over the form.
Description
-*****
The present invention relates to a printing form, and more particularly to a printing form suitable for ~tipelilive printing of the same subject matter, that is, useful in a printing machine, as well as for other reproduction machinery, such as copymachines and the like, in which electrically charged ink or liquid toner elements are selectively and controllably tMnsferred to the printing form by means of an electrostatic field for subsequent transfer to a carrier substrate such as, for example, a web of paper, textile material, plastic foils or the like.
_.~
-A generic process is already known from Japanese laid-open application S63-220177, in which a ferroelectric printing form is used for printing. The printing form has a plane surface to which toner is applied with a dry, powdery toner. Prior to the printing process, the printing form is exposed. For this it is positively and negatively polarized, depending on the image to be printed. In a subsequent development step, the positively charged surface portions of the printing form attract negatively charged toner particles. These are then printed on paper.
From U.S. 3,899,969, a process is known in which printing is done with pyroelectric materials. A pyroelectric film is exposed by subjecting it to an electric field while being held at a tempeMture above the material's specific dipole orientation tempeMture. When the film has cooled down to ambient tempeMture, it is immersed in a warm toner bath, which warms it again so that its surface shows electrical charges which are able to attMct charged toner particles and to accumulate them on the surface of the pyroelectric film. Subsequently the toner particles are tMnsferred to the paper.
In the known process, the pyroelectric effect is utilized for producing the latent image as well as for developing it, i.e. a pyroelectric material that is heated and to which an electric field is applied is permanently poled, and is exposed by immersion in a warm or cold toner bath which contains charged toner particles.
From DE 25 30 290 Al a process and an arMngement for printing and copying are already known in which ferroelectric materials are used. In a first step, an external electric field or mechanical force are applied to a ferroelectric material, which produces the image of a ferroelectric polarization pattern. In a second step, a change of an external electric field, a mechanical force, or heat is produced in the ferroelectric material to bring about a tempoMry change in ferroelectric polarization, which produces an image in the form of a charge pattern on the material surface of the ferroelectric material that corresponds to the pattern of ferroelectric polarization.
.~
...~
-- 2a - 2000343 German Patent 19 57 403 describes a printing form which essentially includes a dielectric having electrodes associated therewith. An ion source and an optical system, controlled by the image, generates a corresponding charge image on the surface of the printing form. Charged toner particles are then accepted on the charged image surface in accordance with the original image. Toner is then transferred from the printing form to the substrate by contact. The charge on the printing form is neutralized upon acceptance of the toner, and thus the printing form must be again programmed with the image before it can carry out a new printing operation. The charge image, thus, must be refreshed or newly generated after each transfer of toner.
U.S. Patent 4,833,990 describes the use of ferroelectric materials in printing machines. The disclosure is specifically directed to offset printing machines using inks conventional with offset printing, that is, oil-based inks in combination with damping liquids, typically water. The system uses the characteristics of ferroelectric material that dirrerenlially polarized localities of the ferroelectric material have dirrelenlial affinity for oil and water. Polarization parts are hydrophilic and accept water, whereas depolarized materials are hydrophobic, so that they can accept printing ink.
The Invention. It is an object to provide a printing form which does not require re-generation of an image each time the ink has been transferred.
Briefly, an ink transferring layer, supported on a support structure, is formed of ferroelectric material; this permits formation of an image pattern on the _....
,~..~
printing form which, once generated, will remain so that ink or toner can be continuously applied to the printing form, for application to a printing substrate without intermediate refreshing or re-generation of the printed image. Once the printing form has been programmed, it will accept toner or ink upon passage past an inker, for transfer of the ink to the substrate, without destruction or discharge of the charge image. This is ln contrast to the prior art system of the referenced Patent 4,833,990, in which the electric field to electrically charge ink elements is not used. In contrast, electrically charged toner or ink particles are applied on the--ferroelectric material which has, previously, been polarized.
In accordance with a feature of the invention, it has been found, surprisingly, that the system permits multi-color printing with a single passage of the substrate past the printing form. The ferroelectric material can be differentially polarized, positively, negatively, or remain neutral within very small areas. Thus, two inks or toners of differentially charged particles can be applied to the respective differentially polarized domains of the ferroelectric material. One ink, for example, can be charged positively, to be attracted by a negative domain, but repelled by a positive domain; another ink of a different color can be charged positively, for attraction by a negative domain and repulsion by a positive domain; and neutral regions of the ferroelectric material will not have any particles adhere thereto. Thus, for multi-color printing, a lesser number of runs through a printing cylinder by the substrate is needed.
The printing form can be used with liquid toners in which a liquid substance acts as a ~ -3-2Q~Q:~43 carrier for the toner.
In accordance with a feature of the invention, the printing form can be either a planar form or a gravure form. Thus, the carrier for the ferroelectric material may be a highly wear-resistant material such as a metal or ceramic formed with cells or receptor depressions as well known in gravure printing technology. The bottomsof the cells or depressions include the ferroelectric material.
The printing form in accordance with the present invention preferably is used with a control system in which the ferroelectric bottoms of the cells are polarized with differential intensity in accordance with the grey tone of the associated image point. Formation of grey tones can be as desired, for example by varying the number of the polarized cells, so that only a binary polarization is needed;
other gravure printing forms, conventional or inverted half-tone systems can be used.
In accordance with a preferred feature of the invention, those cells which should accept ink are polarized oppositely to the cells which should not have any ink therein.
After programming of the gravure form, the cells are filled with a carrier liquid, including toner, or with charged toner particles directly. A doctor blade or stripping roller contacting the surface of the printing form acts on the electrical field effective against the pQlarized bottom of the cells similarly to a counter electrode. Thus, the space between the bottom of the cells and the doctor blade or stripping roller will have a strong electrical field therein which, in dependence on the polarization, deposits toner material at thebottom of the cell or on the doctor blade or stripping ~Q343 roller. By doctoring, thus, the ink or toner quantity within the cells can be controlled. The ink remaining in the cells is transferred to a printing substrate in accordance with conventional gravure printing technology.
Control of ink by doctoring or by a stripping roller is improved by charging the doctor blade or the stripping roller to an~ appropriately high electrical voltage.
Drawings:
Fig. 1 is a highly schematic representation of a printing cylinder having an image applied thereto;
Figs. 2 and 3 illustrate the printing cylinder of Fig. 1 in combination with subsequent steps in the printing method;
Fig. 4 is a highly schematic fragmentary cross-sectional view of a gravure cylinder in a processing step to apply thereto a printing image; and Figs. 5 and 6 show the printing cylinder of Fig. 4 in subsequent steps of the process to obtain a printed image.
Detailed Description.
A cylindrical printing form cylinder 10, Fig. 1, is formed by a hollow cylindrical support structure 11, made of electrically conductive material.
In accordance with a feature of the invention, a layer 12 is applied to the support cylinder 11, the layer 12 having a surface of ferroelectric material. A printing head 14, controlled by a control unit 13 of well known construction, and connected to the electrically conductive cylinder 11, applies a charge image 15 on the ferroelectric layer 12 . The application of the charge image may use well known and Q;~43 conventional methods used to control a dielectric layer.
The charge image will be the sum of the negative polarized raster or domain positions l5 on the ferroelectric material l2, the positively polarized domain positions, and the neutral domain positions. The charges applied to the surface are fixed and bound within the ferroelectric material l2 by orientation of the ferroelectric domains of the material upon polarization. They form a dual layer of charges and oppositely charged domains, which can be disturbed or erased by strong external fields or high temperatures.
Upon contact of the surface with electrically charged toner particles, the surface will not be neutralized, that is, the charge image will not dissappear and the charge will not dissipate or flow off. Polarization of the ferroelectric material remains until the charge image is changed under command of the control unit l3.
The neutral locations l6 remain free of ink toners;
the positive points will attract negatively charged toner or ink particles and the negative points will attract positively charged ink particles or toner particles. The arrangement permits densely packed adjacent domains which may have the same or different polarity, or be neutral, which permits application of inks or toners of two different colors, by charging the ink or toner of one color positively and the ink or toner of another color negatively.
Fig. 2 illustrates application of ink to the cylinder of Fig. l. Two toner containers l7 and l8 are provided, in which, for example, the container l7 retains positively charged yellow ink or toner particles. The second container l8 retains negatively charged red ink or toner particles. When the cylinder ll ~_- 2000343 with the ferroelectric surface 12 thereon rotates past the toner containers 17, 18, brushes 19, 20 within the containers apply the toner or ink particles against the ferroelectric surface 12. The ink particles will then adhere on the printing form 10 in accordance with the charge image 15 applied as explained in connection with Fig. 1.
Upon passage of a web 21, Fig. 3, in contact with the cylinder 11, the ink or toner particles will be transferred to the substrate 21, to be set thereon by a heater 22.
By applying two differently colored inks or toner particles, as explained in connection with Fig. 2, it is possible to obtain multi-color printing on the substrate 21 by a single pass over the cylinder 10, so that the number of passes through a printing station, for multi-color printing, can be reduced by two.
If only a single color ink is to be used, polarization of the ferroelectric surface can be carried out throughout with positive or negative polarity, that is, without the neutral positions or points 16. Different grey scales can then be generated either by differential field strengths, so that the quantity of ink or toner particles attracted is varied;
or they can be generated by applying raster points of differential size, polarized to saturation.
The ink i~ a liquid toner in which charged toner particles suspended within a carrier liquid.
The present invention is applicable not only to planographic printing but also to different types of printing.
Figs. 4 to 6 illustrate an embodiment of the present invention in connection with a gravure printing plate.
A substrate 30 of the system 40 is formed at one of the surfaces with cells or receptor depressions 31,-as well known.
._ -7-- 20~3~3 The substrate is made of a highly wear-resistant material, for example a strong metal or a ceramic. The cells 31 are of uniform size and are located in a matrix or raster formation on the surface of the substrate 30, as well known in gravure printing.
In accordance with a feature of the invention, the bottoms of the cells 31 include a ferroelectric layer 32.
The ferroelectric layers are polarized by an electrode 14 ', coupled to control unit 13 ', in accordance with an image to be transferred, under control of the control unit 13 ', and similar to polarization of the layer or surface 12 as described in connection with Figs. 1-3. After polarizing the layer 32, a toner 33, for example in liquid form, is applied to the cells 31, to fill the cells. The toner, upon filling of the cells, may extend slightly thereover, and in order to provide a smooth surface, excess liquid 33 is stripped off by a doctor blade 34.
As schematically shown in Fig. 5, the toner particles have been pre-charged to receive a positive charge if the polarization of the ferroelectric surface 32 was negative, so that the toner will be electrostatically retained in the cells. The extent of polarization can be controlled from the control unit 13 ', so that the polarization is more or less negative. The doctor blade 34 is negatively charged, which, in dependence on the intensity of the polarity of the ferroelectric material 32, will draw out some of the toner 33 as the doctor blade runs or rides across the cells 31. Thus,the quantity of ink within the cells is controlled or a function of the extent of polarization applied by the electrode 14 ' under control of the control unit 13 ' .
The cells 31 will retain that quantity of ink pigments which 30 corresponds to the respective field strength of the associated 2~ 3 -ferroelectric material 32 within the respective cell.
The remaining quantity of toner particles thus will correspond to the desired grey-value. As illustrated in Fig. 6, the thus properly quantified or dosed ink is transferred to the 5 substrate material 35 which is to be printed. After printing, the gravure element 30 can be refilled with polarized toner and passed beneath the doctor blade 34 (Fig. 5) and another printing substrate 35 can be printed.
The invention is applicable to various types of printing forms, but particularly to planographic printing and to gravure printing; for planographic printing, see Figs. 1-3, the surface of the printing element, be it a cylinder or a flat plate, which will come in contact with the substrate to be printed is supplied with a ferroelectric layer 12. This printing form is then polarized, by the control unit 13 controlling the electrode 14 in a system which is well known and customary in electrostatic control of printing forms. The surface of the printing form is thus polarized in accordance with image information, in matrix or raster form; each image point or pixle will be more or less polarized in dependence on the associated grey-value of the respective pixle;
or, if the ferroelectric layer is already subdivided into cells, see layer 33, Figs. 4-6, the polarization can be directly carried out with respect to the particular cells. The thus generated charge pattern, representing the image to be printed as controlled by the control unit 13, 13', then is brought into contact with an arrangement to apply ink, for example the brushes 19, 20 (Fig. 2) which apply a dry toner or a toner in suspension against the polarized surface 12, which will accept, in point-by-point pattern, more or less ink on the specific local point areas. Upon contact of the surface, which has thus 2Q~ 3 been inked, with a printing substrate and, if desired, a counter electrode, ink is transferred to the printing substrate.
Rather than using a dry toner, a liquid toner in which the toner particles or ink is suspended in the carrier liquid can be used.
The printing form in accordance with the present invention can also be used in a different manner, namely by applying the toner, in accordance with the image to be printed, on the printing form and then securing or fixing it thereon by application of heat, pressure, or chemical adhering reactions. The toner will then be fixed or attached to the printing form. The toner will, on the printing form, provide a hydrophobic region, in accordance with the image to be printed,which, however, will be oleophilic, that is, accepting fatty inks. Those regions of the printing form which are free from toner are hydrophilic, that is, water-accepting.
Use of the method in accordance with the present invention in this way has an advantage with respect to known printing forms, in that the fixed ink regions can be re-generated without additional control thereof by the electrode l 4, l 4 ' under control of the control unit l 3, l 3 ' . Long or extensive printing runs may cause the fixed toner to flake or peel off the printing form; under such conditions, the hydrophobic and hence oleophilic regions must be regenerated. Printing forms with dielectric layers require re-programming by the control unit l3, l3' and the electrode l4, 14'; the printing form, however, the ferroelectric layer has the advantage that it is only necessary to re-apply toner, and renewed refreshing of the previously commanded image information, that is, regeneration of the polarized regions is not necessary.
~30Q3~3 The printing forms may be used in printing machines, as well as other multiplication apparatus, such as copiers and the like.
Various changes and modifications may be made and any features described herein may be used with any of the others, within the scope of the inventive concept.
The present invention relates to a printing form, and more particularly to a printing form suitable for ~tipelilive printing of the same subject matter, that is, useful in a printing machine, as well as for other reproduction machinery, such as copymachines and the like, in which electrically charged ink or liquid toner elements are selectively and controllably tMnsferred to the printing form by means of an electrostatic field for subsequent transfer to a carrier substrate such as, for example, a web of paper, textile material, plastic foils or the like.
_.~
-A generic process is already known from Japanese laid-open application S63-220177, in which a ferroelectric printing form is used for printing. The printing form has a plane surface to which toner is applied with a dry, powdery toner. Prior to the printing process, the printing form is exposed. For this it is positively and negatively polarized, depending on the image to be printed. In a subsequent development step, the positively charged surface portions of the printing form attract negatively charged toner particles. These are then printed on paper.
From U.S. 3,899,969, a process is known in which printing is done with pyroelectric materials. A pyroelectric film is exposed by subjecting it to an electric field while being held at a tempeMture above the material's specific dipole orientation tempeMture. When the film has cooled down to ambient tempeMture, it is immersed in a warm toner bath, which warms it again so that its surface shows electrical charges which are able to attMct charged toner particles and to accumulate them on the surface of the pyroelectric film. Subsequently the toner particles are tMnsferred to the paper.
In the known process, the pyroelectric effect is utilized for producing the latent image as well as for developing it, i.e. a pyroelectric material that is heated and to which an electric field is applied is permanently poled, and is exposed by immersion in a warm or cold toner bath which contains charged toner particles.
From DE 25 30 290 Al a process and an arMngement for printing and copying are already known in which ferroelectric materials are used. In a first step, an external electric field or mechanical force are applied to a ferroelectric material, which produces the image of a ferroelectric polarization pattern. In a second step, a change of an external electric field, a mechanical force, or heat is produced in the ferroelectric material to bring about a tempoMry change in ferroelectric polarization, which produces an image in the form of a charge pattern on the material surface of the ferroelectric material that corresponds to the pattern of ferroelectric polarization.
.~
...~
-- 2a - 2000343 German Patent 19 57 403 describes a printing form which essentially includes a dielectric having electrodes associated therewith. An ion source and an optical system, controlled by the image, generates a corresponding charge image on the surface of the printing form. Charged toner particles are then accepted on the charged image surface in accordance with the original image. Toner is then transferred from the printing form to the substrate by contact. The charge on the printing form is neutralized upon acceptance of the toner, and thus the printing form must be again programmed with the image before it can carry out a new printing operation. The charge image, thus, must be refreshed or newly generated after each transfer of toner.
U.S. Patent 4,833,990 describes the use of ferroelectric materials in printing machines. The disclosure is specifically directed to offset printing machines using inks conventional with offset printing, that is, oil-based inks in combination with damping liquids, typically water. The system uses the characteristics of ferroelectric material that dirrerenlially polarized localities of the ferroelectric material have dirrelenlial affinity for oil and water. Polarization parts are hydrophilic and accept water, whereas depolarized materials are hydrophobic, so that they can accept printing ink.
The Invention. It is an object to provide a printing form which does not require re-generation of an image each time the ink has been transferred.
Briefly, an ink transferring layer, supported on a support structure, is formed of ferroelectric material; this permits formation of an image pattern on the _....
,~..~
printing form which, once generated, will remain so that ink or toner can be continuously applied to the printing form, for application to a printing substrate without intermediate refreshing or re-generation of the printed image. Once the printing form has been programmed, it will accept toner or ink upon passage past an inker, for transfer of the ink to the substrate, without destruction or discharge of the charge image. This is ln contrast to the prior art system of the referenced Patent 4,833,990, in which the electric field to electrically charge ink elements is not used. In contrast, electrically charged toner or ink particles are applied on the--ferroelectric material which has, previously, been polarized.
In accordance with a feature of the invention, it has been found, surprisingly, that the system permits multi-color printing with a single passage of the substrate past the printing form. The ferroelectric material can be differentially polarized, positively, negatively, or remain neutral within very small areas. Thus, two inks or toners of differentially charged particles can be applied to the respective differentially polarized domains of the ferroelectric material. One ink, for example, can be charged positively, to be attracted by a negative domain, but repelled by a positive domain; another ink of a different color can be charged positively, for attraction by a negative domain and repulsion by a positive domain; and neutral regions of the ferroelectric material will not have any particles adhere thereto. Thus, for multi-color printing, a lesser number of runs through a printing cylinder by the substrate is needed.
The printing form can be used with liquid toners in which a liquid substance acts as a ~ -3-2Q~Q:~43 carrier for the toner.
In accordance with a feature of the invention, the printing form can be either a planar form or a gravure form. Thus, the carrier for the ferroelectric material may be a highly wear-resistant material such as a metal or ceramic formed with cells or receptor depressions as well known in gravure printing technology. The bottomsof the cells or depressions include the ferroelectric material.
The printing form in accordance with the present invention preferably is used with a control system in which the ferroelectric bottoms of the cells are polarized with differential intensity in accordance with the grey tone of the associated image point. Formation of grey tones can be as desired, for example by varying the number of the polarized cells, so that only a binary polarization is needed;
other gravure printing forms, conventional or inverted half-tone systems can be used.
In accordance with a preferred feature of the invention, those cells which should accept ink are polarized oppositely to the cells which should not have any ink therein.
After programming of the gravure form, the cells are filled with a carrier liquid, including toner, or with charged toner particles directly. A doctor blade or stripping roller contacting the surface of the printing form acts on the electrical field effective against the pQlarized bottom of the cells similarly to a counter electrode. Thus, the space between the bottom of the cells and the doctor blade or stripping roller will have a strong electrical field therein which, in dependence on the polarization, deposits toner material at thebottom of the cell or on the doctor blade or stripping ~Q343 roller. By doctoring, thus, the ink or toner quantity within the cells can be controlled. The ink remaining in the cells is transferred to a printing substrate in accordance with conventional gravure printing technology.
Control of ink by doctoring or by a stripping roller is improved by charging the doctor blade or the stripping roller to an~ appropriately high electrical voltage.
Drawings:
Fig. 1 is a highly schematic representation of a printing cylinder having an image applied thereto;
Figs. 2 and 3 illustrate the printing cylinder of Fig. 1 in combination with subsequent steps in the printing method;
Fig. 4 is a highly schematic fragmentary cross-sectional view of a gravure cylinder in a processing step to apply thereto a printing image; and Figs. 5 and 6 show the printing cylinder of Fig. 4 in subsequent steps of the process to obtain a printed image.
Detailed Description.
A cylindrical printing form cylinder 10, Fig. 1, is formed by a hollow cylindrical support structure 11, made of electrically conductive material.
In accordance with a feature of the invention, a layer 12 is applied to the support cylinder 11, the layer 12 having a surface of ferroelectric material. A printing head 14, controlled by a control unit 13 of well known construction, and connected to the electrically conductive cylinder 11, applies a charge image 15 on the ferroelectric layer 12 . The application of the charge image may use well known and Q;~43 conventional methods used to control a dielectric layer.
The charge image will be the sum of the negative polarized raster or domain positions l5 on the ferroelectric material l2, the positively polarized domain positions, and the neutral domain positions. The charges applied to the surface are fixed and bound within the ferroelectric material l2 by orientation of the ferroelectric domains of the material upon polarization. They form a dual layer of charges and oppositely charged domains, which can be disturbed or erased by strong external fields or high temperatures.
Upon contact of the surface with electrically charged toner particles, the surface will not be neutralized, that is, the charge image will not dissappear and the charge will not dissipate or flow off. Polarization of the ferroelectric material remains until the charge image is changed under command of the control unit l3.
The neutral locations l6 remain free of ink toners;
the positive points will attract negatively charged toner or ink particles and the negative points will attract positively charged ink particles or toner particles. The arrangement permits densely packed adjacent domains which may have the same or different polarity, or be neutral, which permits application of inks or toners of two different colors, by charging the ink or toner of one color positively and the ink or toner of another color negatively.
Fig. 2 illustrates application of ink to the cylinder of Fig. l. Two toner containers l7 and l8 are provided, in which, for example, the container l7 retains positively charged yellow ink or toner particles. The second container l8 retains negatively charged red ink or toner particles. When the cylinder ll ~_- 2000343 with the ferroelectric surface 12 thereon rotates past the toner containers 17, 18, brushes 19, 20 within the containers apply the toner or ink particles against the ferroelectric surface 12. The ink particles will then adhere on the printing form 10 in accordance with the charge image 15 applied as explained in connection with Fig. 1.
Upon passage of a web 21, Fig. 3, in contact with the cylinder 11, the ink or toner particles will be transferred to the substrate 21, to be set thereon by a heater 22.
By applying two differently colored inks or toner particles, as explained in connection with Fig. 2, it is possible to obtain multi-color printing on the substrate 21 by a single pass over the cylinder 10, so that the number of passes through a printing station, for multi-color printing, can be reduced by two.
If only a single color ink is to be used, polarization of the ferroelectric surface can be carried out throughout with positive or negative polarity, that is, without the neutral positions or points 16. Different grey scales can then be generated either by differential field strengths, so that the quantity of ink or toner particles attracted is varied;
or they can be generated by applying raster points of differential size, polarized to saturation.
The ink i~ a liquid toner in which charged toner particles suspended within a carrier liquid.
The present invention is applicable not only to planographic printing but also to different types of printing.
Figs. 4 to 6 illustrate an embodiment of the present invention in connection with a gravure printing plate.
A substrate 30 of the system 40 is formed at one of the surfaces with cells or receptor depressions 31,-as well known.
._ -7-- 20~3~3 The substrate is made of a highly wear-resistant material, for example a strong metal or a ceramic. The cells 31 are of uniform size and are located in a matrix or raster formation on the surface of the substrate 30, as well known in gravure printing.
In accordance with a feature of the invention, the bottoms of the cells 31 include a ferroelectric layer 32.
The ferroelectric layers are polarized by an electrode 14 ', coupled to control unit 13 ', in accordance with an image to be transferred, under control of the control unit 13 ', and similar to polarization of the layer or surface 12 as described in connection with Figs. 1-3. After polarizing the layer 32, a toner 33, for example in liquid form, is applied to the cells 31, to fill the cells. The toner, upon filling of the cells, may extend slightly thereover, and in order to provide a smooth surface, excess liquid 33 is stripped off by a doctor blade 34.
As schematically shown in Fig. 5, the toner particles have been pre-charged to receive a positive charge if the polarization of the ferroelectric surface 32 was negative, so that the toner will be electrostatically retained in the cells. The extent of polarization can be controlled from the control unit 13 ', so that the polarization is more or less negative. The doctor blade 34 is negatively charged, which, in dependence on the intensity of the polarity of the ferroelectric material 32, will draw out some of the toner 33 as the doctor blade runs or rides across the cells 31. Thus,the quantity of ink within the cells is controlled or a function of the extent of polarization applied by the electrode 14 ' under control of the control unit 13 ' .
The cells 31 will retain that quantity of ink pigments which 30 corresponds to the respective field strength of the associated 2~ 3 -ferroelectric material 32 within the respective cell.
The remaining quantity of toner particles thus will correspond to the desired grey-value. As illustrated in Fig. 6, the thus properly quantified or dosed ink is transferred to the 5 substrate material 35 which is to be printed. After printing, the gravure element 30 can be refilled with polarized toner and passed beneath the doctor blade 34 (Fig. 5) and another printing substrate 35 can be printed.
The invention is applicable to various types of printing forms, but particularly to planographic printing and to gravure printing; for planographic printing, see Figs. 1-3, the surface of the printing element, be it a cylinder or a flat plate, which will come in contact with the substrate to be printed is supplied with a ferroelectric layer 12. This printing form is then polarized, by the control unit 13 controlling the electrode 14 in a system which is well known and customary in electrostatic control of printing forms. The surface of the printing form is thus polarized in accordance with image information, in matrix or raster form; each image point or pixle will be more or less polarized in dependence on the associated grey-value of the respective pixle;
or, if the ferroelectric layer is already subdivided into cells, see layer 33, Figs. 4-6, the polarization can be directly carried out with respect to the particular cells. The thus generated charge pattern, representing the image to be printed as controlled by the control unit 13, 13', then is brought into contact with an arrangement to apply ink, for example the brushes 19, 20 (Fig. 2) which apply a dry toner or a toner in suspension against the polarized surface 12, which will accept, in point-by-point pattern, more or less ink on the specific local point areas. Upon contact of the surface, which has thus 2Q~ 3 been inked, with a printing substrate and, if desired, a counter electrode, ink is transferred to the printing substrate.
Rather than using a dry toner, a liquid toner in which the toner particles or ink is suspended in the carrier liquid can be used.
The printing form in accordance with the present invention can also be used in a different manner, namely by applying the toner, in accordance with the image to be printed, on the printing form and then securing or fixing it thereon by application of heat, pressure, or chemical adhering reactions. The toner will then be fixed or attached to the printing form. The toner will, on the printing form, provide a hydrophobic region, in accordance with the image to be printed,which, however, will be oleophilic, that is, accepting fatty inks. Those regions of the printing form which are free from toner are hydrophilic, that is, water-accepting.
Use of the method in accordance with the present invention in this way has an advantage with respect to known printing forms, in that the fixed ink regions can be re-generated without additional control thereof by the electrode l 4, l 4 ' under control of the control unit l 3, l 3 ' . Long or extensive printing runs may cause the fixed toner to flake or peel off the printing form; under such conditions, the hydrophobic and hence oleophilic regions must be regenerated. Printing forms with dielectric layers require re-programming by the control unit l3, l3' and the electrode l4, 14'; the printing form, however, the ferroelectric layer has the advantage that it is only necessary to re-apply toner, and renewed refreshing of the previously commanded image information, that is, regeneration of the polarized regions is not necessary.
~30Q3~3 The printing forms may be used in printing machines, as well as other multiplication apparatus, such as copiers and the like.
Various changes and modifications may be made and any features described herein may be used with any of the others, within the scope of the inventive concept.
Claims (14)
1. Printing form (10, 40) for reproducing an image, comprising an ink transferring layer (12, 32);
means (11, 30) for supporting said ink transferring layer (12, 32), wherein said ink transferring layer (12, 32) of the printing form (10, 40) comprises ferroelectric material for, selectively, attracting oppositely electrically charged liquid ink elements against said ink transferring layer (12, 32).
means (11, 30) for supporting said ink transferring layer (12, 32), wherein said ink transferring layer (12, 32) of the printing form (10, 40) comprises ferroelectric material for, selectively, attracting oppositely electrically charged liquid ink elements against said ink transferring layer (12, 32).
2. The printing form of claim 1, wherein said supporting means comprises a carrier structure (11, 30) having at least one ink transferring surface;
and wherein said ink transferring surface comprises said ink transferring layer (12) in form of a surface coating.
and wherein said ink transferring surface comprises said ink transferring layer (12) in form of a surface coating.
3. The printing form of claim 1, wherein said means for supporting the ink transferring layer (32) comprises a substrate (30) of wear-resistant material formed with gravure cells (31);
and wherein said ink transferring layer (12) of ferroelectric material is located on the bottom of the gravure cells.
and wherein said ink transferring layer (12) of ferroelectric material is located on the bottom of the gravure cells.
4. The printing form of claim 3, further including a control unit (13') and an electrode (14'), the electrode being positioned in electrical field-transferring relation with respect to the ferroelectric layer (32) in the gravure cells (31), and said control unit controlling said electrode for selectively more or less intense polarization in a predetermined direction of polarity.
5. The printing form of claim 1, wherein said support means for the ink transferring layer comprises an essentially smooth surface coated by said ink transferring layer (12) of ferroelectric material.
6. The printing form of claim 1, further including electrode means (14, 14') positioned in electric field transfer relation with respect to said ink transferring layer (12) of ferroelectric material;
control means (13, 13') controlling the electrode means (14, 14') for applying an electric field to said ink transferring layer of ferroelectric material (12); and wherein said control means (13, 13') selectively control the electrode means (14, 14') to polarize the ferroelectric ink transferring layer (12), selectively, in either positive polarity, negative polarity, or to leave selected areas of said ink transferring layer (12) unpolarized.
control means (13, 13') controlling the electrode means (14, 14') for applying an electric field to said ink transferring layer of ferroelectric material (12); and wherein said control means (13, 13') selectively control the electrode means (14, 14') to polarize the ferroelectric ink transferring layer (12), selectively, in either positive polarity, negative polarity, or to leave selected areas of said ink transferring layer (12) unpolarized.
7. A printing system comprising the printing form of claim 1 wherein said layer of ferroelectric material (12, 32) is selectively charged to have domains of at least one selected polarity; and liquid ink particles electrically charged with opposite polarity, attracted and adhered to said selectively charged domains.
8. A method of printing comprising providing a printing form support (11, 30) having thereon an ink transferring layer (12, 32) of ferroelectric material;
polarizing said ink transferring layer (12, 32) of ferroelectric material, selectively, point-by-point, in accordance with an image to be reproduced, in a selected direction of polarization; and applying on said ink transferring ferroelectric layer (12, 32) liquid toner or ink particles charged with a polarity opposite the polarity of polarization of the respective points of the ink transferring ferroelectric layer (12, 32) so that said toner or ink particles adhere to said oppositely charged ferroelectric material.
polarizing said ink transferring layer (12, 32) of ferroelectric material, selectively, point-by-point, in accordance with an image to be reproduced, in a selected direction of polarization; and applying on said ink transferring ferroelectric layer (12, 32) liquid toner or ink particles charged with a polarity opposite the polarity of polarization of the respective points of the ink transferring ferroelectric layer (12, 32) so that said toner or ink particles adhere to said oppositely charged ferroelectric material.
9. A method of printing comprising providing a printing form support element (11, 30) said printing form support element having a surface consisting of a layer (12, 32) of ferroelectric material which, in specific area locations thereof, is selectively polarized in a predetermined direction of polarity;
and comprising the step of applying, on said selectively polarized layer (12, 32) of ferroelectric material, an electrostatically oppositely charged liquid toner material so that said toner material adheres to said oppositely charged area locations of said ferroelectric material, said toner material having the characteristic of at least one of:
capability of transfer to a printing substrate (21, 35) selective acceptance or rejection on the surface of said toner of printing ink and printing damping fluid.
and comprising the step of applying, on said selectively polarized layer (12, 32) of ferroelectric material, an electrostatically oppositely charged liquid toner material so that said toner material adheres to said oppositely charged area locations of said ferroelectric material, said toner material having the characteristic of at least one of:
capability of transfer to a printing substrate (21, 35) selective acceptance or rejection on the surface of said toner of printing ink and printing damping fluid.
10. Process for reproducing an original image by means of a printing form (10) whose surface contains a layer (12) made of a ferroelectric material, whereby through the polarization of the ferroelectric layer (12) charges are applied as images to the surface, the charges - until the polarization is changed by means of a control unit (13) - are fixed through the direction of the ferroelectric domains of the material of the layer (12) during polarization, and the layer (12) is brought in contract with electrically charged toner particles which adhere to variably polarized portions of the ferroelectric material, characterized in that the printing form (10) is applied with the layer (12) to a cylindrical carrier (11), that the toner particles are applied form a toner fluid to the layer (12) and that by means of rotations of the cylindrical carrier (11) a stock (21) is printed in a continuous printing process.
11. Process according to claim 10, characterized in that the electrically charged toner elements are fixed on the printing form (10) for the formation of hydrophobic areas.
12. The process according to claim 10, characterized in that a printing form (10) is used which consists of a substrate (30) made of a wear-resistant material and is provided on one side with gravure cells, whereby the bottom of the cells is made of ferroelectric material (32).
13. The process according to claim 11, characterized in that a printing form (10) is used which consists of a substrate (30) made of a wear-resistant material and is provided on one side with gravure cells, whereby the bottom of the cells is made of ferroelectric material (32).
14. The process according to one of claims 10 to 13, characterized in that a printing form (10) is used which is provided with a driver unit (13, 13', 14, 14') with which the ferroelectric material is polarized to variable degrees.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3835091A DE3835091A1 (en) | 1988-10-14 | 1988-10-14 | PRINTING FORM |
| DEP3835091.2 | 1988-10-14 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2000343A1 CA2000343A1 (en) | 1990-04-14 |
| CA2000343C true CA2000343C (en) | 1996-10-29 |
Family
ID=6365159
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002000343A Expired - Fee Related CA2000343C (en) | 1988-10-14 | 1989-10-10 | Electrostatically controllable printing form |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0363932B1 (en) |
| JP (1) | JP2708066B2 (en) |
| CA (1) | CA2000343C (en) |
| DE (2) | DE3835091A1 (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5213931A (en) * | 1990-05-24 | 1993-05-25 | Man Roland Druckmaschinen Ag | Method and means for hydraulic meniscus toning of ferro electric materials |
| WO1991018743A1 (en) * | 1990-05-31 | 1991-12-12 | Ludwig Bartl | Process and device for printing variable information |
| DE4140996C2 (en) * | 1991-12-12 | 2001-10-11 | Fogra Forschungsgesellschaft D | Electrophotographic printing process, printing form and process for producing this printing form |
| DE4328037A1 (en) | 1993-08-20 | 1995-03-02 | Roland Man Druckmasch | Printing process with ferroelectrics |
| DE19521187C2 (en) * | 1995-06-10 | 1997-08-07 | Fraunhofer Ges Forschung | Use of a ferroelectric ceramic material for information storage in electrostatic printing processes |
| DE19601586C1 (en) * | 1996-01-18 | 1997-07-10 | Roland Man Druckmasch | Ferroelectric printing form production method |
| US6146798A (en) * | 1998-12-30 | 2000-11-14 | Xerox Corporation | Printing plate with reversible charge-controlled wetting |
| DE10052853A1 (en) * | 2000-10-25 | 2002-05-08 | Anton Rodi | Relief pattern of pixel elements are produced on the surface of a polycrystalline ceramic |
| DE10125545A1 (en) * | 2001-05-23 | 2002-11-28 | Heidelberger Druckmasch Ag | Printing method and device |
| KR100975994B1 (en) * | 2006-03-02 | 2010-08-17 | 가부시끼가이샤 도시바 | Cleaning apparatus, cleaning method, pattern forming apparatus and pattern forming method |
| EP1995060A1 (en) * | 2007-05-22 | 2008-11-26 | Ernst-Rudolf Dr. Weidlich | Method for influencing the colour content and/or colour dispensing ability of printing plates and printing device |
| EP3900934B1 (en) * | 2020-04-21 | 2022-05-18 | Flooring Technologies Ltd. | Device for generating a print on a printing material and method for producing a plurality of cavities on a printing form with a magnetic raster |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1127830A (en) * | 1965-10-24 | 1968-09-18 | Continental Can Co | Apparatus for intaglio electrostatic printing |
| CA1001704A (en) * | 1968-11-15 | 1976-12-14 | Thomas D. Kittredge | Apparatus for aperture controlled electrostatic image reproduction or constitution |
| GB1311673A (en) * | 1969-03-12 | 1973-03-28 | Masson Scott Thrissell Eng Ltd | Methods and apparatus for electrostatic printing or copying |
| US3765330A (en) * | 1971-01-06 | 1973-10-16 | Xerox Corp | Xeroprinting employing letterpress surface covered with a layer of resistive material |
| US3801315A (en) * | 1971-12-27 | 1974-04-02 | Xerox Corp | Gravure imaging system |
| US3951533A (en) * | 1974-09-20 | 1976-04-20 | Xerox Corporation | Color image reproduction system |
| DE3633758A1 (en) * | 1986-10-03 | 1988-04-07 | Man Technologie Gmbh | PRINTING MACHINE |
| GB2198085B (en) * | 1986-11-29 | 1991-02-13 | Stc Plc | Printing apparatus and process |
| JP2581059B2 (en) * | 1987-03-09 | 1997-02-12 | ミノルタ株式会社 | Latent image writing method and image forming method using the same |
| JPS63220259A (en) * | 1987-03-10 | 1988-09-13 | Ricoh Co Ltd | Image forming method |
-
1988
- 1988-10-14 DE DE3835091A patent/DE3835091A1/en active Granted
-
1989
- 1989-10-10 CA CA002000343A patent/CA2000343C/en not_active Expired - Fee Related
- 1989-10-11 EP EP89118900A patent/EP0363932B1/en not_active Expired - Lifetime
- 1989-10-11 DE DE58909754T patent/DE58909754D1/en not_active Expired - Fee Related
- 1989-10-16 JP JP1266384A patent/JP2708066B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2000343A1 (en) | 1990-04-14 |
| DE3835091A1 (en) | 1990-04-19 |
| JP2708066B2 (en) | 1998-02-04 |
| EP0363932B1 (en) | 1996-12-11 |
| DE58909754D1 (en) | 1997-01-23 |
| JPH02217871A (en) | 1990-08-30 |
| EP0363932A3 (en) | 1990-11-22 |
| DE3835091C2 (en) | 1991-06-06 |
| EP0363932A2 (en) | 1990-04-18 |
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| EEER | Examination request | ||
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