WO2006051484A2

WO2006051484A2 - Printer device for printing tactile information

Info

Publication number: WO2006051484A2
Application number: PCT/IB2005/053668
Authority: WO
Inventors: Maria E. Mena Benito; Ralph Kurt; Dirk J. Broer
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2004-11-10
Filing date: 2005-11-08
Publication date: 2006-05-18
Also published as: WO2006051484A3

Abstract

The present invention relates to a printer device for printing information as a tactile relief structure on a medium, which on at least one side is coated with a polymerizable composition comprising a stationary phase component, polymerizable monomers and a radiation inducible polymerization initiator. The printer device comprises an addressable irradiation system, arranged to irradiate an addressed area of a polymerizable composition on medium located in said device. A radiation induced polymerization is induced in said addressed area to effect polymerization induced diffusion of polymerizable monomers towards said addressed area. Thus, a tactile relief structure develops in said composition on said medium.

Description

Printer device for printing tactile information

TECHNICAL FIELD

The present invention relates to a printer device for printing information as a tactile relief structure on a medium, a medium for presenting information as a tactile relief structure and a method for developing information on a medium as a tactile relief structure.

BACKGROUND

Tactile information, such as information embedded in a relief structure that is perceptible by touch, is important and useful in many different aspects.

For example, Braille printing allows for blind people to read texts, and tactile information in form of different groups of geometric structures are for instance provided on banknotes to allow blind people to recognize the different values of different banknotes.

Information embedded in a relief structure can also be used as a copy protection, providing watermarks able to be felt but not easily copied on documents such as checks, banknotes, credit cards, passports etc. Braille text is conventionally obtained by a multi-step processing, including embossing the Braille dots on a metal plate to produce a master stamp, and then use this stamp to transfer the information to paper.

Also other types of tactile information, such as pictures, diagrams, graphs, etc, in tactile form requires the use of a master stamp. The need for a master stamp makes these methods unsuitable for printing of single or low copy number documents.

For blind people, it would be desirable to be able to print out plain text documents, such as e-mails and SMS-messages, as Braille text documents or to print out pictures, as a tactile relief structures, optionally in combination with the original, visible information. This would require a method to print out single documents in Braille text form and with relief structures respectively in an economically feasible way, without the need for a master stamp.

One method to eliminate the need for a master stamp when printing tactile information is disclosed in US patent application no 2004/0054030, describing a photo curable printing ink, comprising a mixture of polymerizable polymer precursors and a photo initiator, with a certain viscosity, as well as a printer for ink jet printing and subsequent photo polymerization of this photo curable printing ink to obtain Braille text on for example a paper surface. The resolution of information printed with this method is however limited to the resolution of the ink jet printing system. Furthermore, since discrete drops of the ink is applied on discrete locations of the surface of the paper, the resulting information is sensitive to mechanical influences, such as scratching, and thus some information may accidentally be . removed from the paper. Thus, there exists a need for methods and means for printing tactile information with high resolution and/or high resistance to mechanical influences, such as scratches, and methods and means for obtaining such tactile information in a manner that is economically feasible, also in the case of printing single or just a few copies of the information.

SUMMARY OF THE INVENTION

One object of the present invention is to overcome at least some of the above mentioned problems, and to provide means and methods for printing tactile information with high resolution, high resistance to mechanical influence and in an economically feasible manner. This is achieved by providing a printer device for printing tactile information on a medium, a medium for presenting information as a tactile relief structure and a method for developing information on a medium as a tactile relief structure.

The above printer device, medium and method is based on photo-embossing techniques. One such technique is described by de Witz, C and Broer, D in "Photo- embossing as a tool for creating complex surface relief structures", Polymer Preprints (America Chemical Society, Division of Chemistry) 2003, 44(2), pp 236-237.

Photo-embossing relates to a process in which light is used to induce mass transport in a layer of a polymerizable composition comprising reactive monomers. A radiation induced local polymerization is effected in a composition comprising a stationary phase, such as a polymer, reactive monomers and a radiation inducible polymerization initiator, at a temperature where the monomer diffusion mobility through the stationary phase is low. When the temperature later is increased, the viscosity of the stationary phase decreases, yielding an increase in monomer diffusion mobility, and thus, a polymerization induced diffusion of monomers towards the area of local polymerization is effected, causing a local volume change in the polymerizing area. The volume change may be positive (protrusion) or negative (recess), for example depending on the steric properties of the monomers compared with the steric properties of the polymer formed by polymerizing the monomers. If the formed polymer occupies much less space per monomer than the monomers themselves, the volume change may be negative. However, usually the volume change is positive.

The article by de Witz and Broer discloses the use of such a process for the manufacture of surface holographic structures. Three examples of structures obtainable by this method is shown in Fig.ure 1 , a-c. The structures are shown as measured by atomic force microscopy.

The structure in Fig. Ia is obtained by radiating the composition through a mask transmitting radiation in rows of 8 μm width separated by non-transmitting rows of 8 μm width and then developing the structure by heating.

The structure in Fig. Ib is obtained by radiation through a mask transmitting radiation in squares of 10 x 10 μm separated by 10 μm wide non-transmitting rows and columns and then developing the structure by heating.

The structure in Fig. 1 c is obtained by a two step radiation procedure. First, the composition is exposed through a chess-board like structure of alternating 3 x 3 μm transmitting and non-transmitting squares. Secondly, the composition is exposed through a mask transmitting radiation in rows of 32 μm width separated by non-transmitting rows of 32 μm width and then developing the structure by heating.

Thus, protrusions from ranging from approximately 0,2 to 1 μm in height and approximately from 3 to 32 μm wide are formed on a surface. The shown surface profiles are obtained by selectively irradiate the parts of the surface that will develop the protrusions, and thus it will be apparent to those skilled in the art that other surface profiles are also possible to obtain with this method.

The inventors have now found that the dimensions, i.e. the width and the height, of the structures that are obtainable by photo-embossing methods are big enough to be perceptible by touch, for example with the tip of a finger. The human finger is capable of feeling a height difference between a smooth surface and a 1 μm step. This means that certain parts of the human body, such as the fingertips, are very sensitive, even for small signals.

Thus, the inventors have realized that a photo-embossing process may be used to produce tactile information, i.e. information perceptible by touch, such as Braille text or tactile contour images on the surface of a medium. The protrusions shown in Fig.ure 1 are obtained from a 3 μm thick layer of polymerizable composition. By increasing the thickness of the layer, higher protrusions should be feasible.

In a first aspect, the present invention thus provides a printer device for printing information as a tactile relief structure on a medium, which on at least one side is coated with a polymerizable composition comprising a stationary phase component, polymerizable monomers and a radiation inducible polymerization initiator. The printer device comprises an addressable irradiation system, arranged to irradiate an addressed area of a polymerizable composition on medium located in said device. Thereby a radiation induced polymerization is induced in said addressed area to effect polymerization induced diffusion of polymerizable monomers towards said addressed area. Thus, a tactile relief structure develops in said composition on said medium.

As used herein, the terms "tactile information" and "information as a tactile relief structure" refers to information that is provided on the surface of a medium and that is perceptible by touch. Non- limiting examples of such tactile information is Braille text and images represented by, for example, tactile contour lines.

As used herein, the term "relief structure" refers to both protrusions on and recesses in a surface.

Preferably, the printer device comprises a heating source arranged to heat at least part of said irradiated area of said medium, to facilitate said polymerization induced diffusion. In the polymerizable composition of the medium, the monomer diffusion is higher at a higher temperature, since the viscosity of the stationary phase becomes lower with increased temperature. Thus, a heating source may help to promote the diffusion.

Preferably, the monomer diffusion at the temperature at the irradiation step is so low that essentially no diffusion occurs. This leads to the formation of a latent relief structure. When the temperature of the composition is increased, the monomer diffusional mobility increases, and the latent relief structure develops. This allows for several different radiation steps to be combined before the tactile information is developed.

In certain mediums suitable for use with the present printer device, the height of the developed protrusion varies with the radiation dose.

Thus, it may be advantageous that the irradiation system is arranged to provide said medium with a variable intensity of radiation to provide a variable height of the tactile relief structure. The addressable irradiation system in the printer device preferably comprises an irradiation source and an addressing system being capable of directing the radiation from the irradiation source towards an addressed area.

The addressable irradiation system further comprises means for directing the radiation towards an addressed area.

One example of a means for directing the radiation comprises a mask being arranged between the radiation source and the medium, wherein the mask is provided with at least one area capable of transmitting light from the radiation source towards the addressed area, and at least one area blocking the radiation from radiation source to prevent the radiation from reaching the medium. Such a mask can for example be a fixed, replaceable mask which can be replaced with another mask when a different set of tactile information is to be produced, or a programmable mask, such as a programmable switching liquid crystal layer sandwiched between a pair of polarizers.

Another example of a means for directing the radiation comprises a position controlling system being arranged to control the position of radiation source relative to the medium so that radiation from the radiation source irradiates an addressed area of a medium.

Yet another example of a means for directing the radiation comprises a system of at least one mirror being arranged to direct radiation from the radiation source towards an addressed area of a medium. The irradiation system of the printer device according to the present invention may comprise any source of irradiation suitable for activating polymerization in a polymerizable composition, including sources of γ-radiation, electrons, UV-light and visible light.

The printer device of the present invention may further comprise means for fixating a developed tactile relief structure. By depleting an area surrounding a developed relief structure of polymerizable monomers, the polymerization induced diffusion is stopped, and thereby, the relief structure becomes fixed.

Such fixating means may, in the case of radiation inducible fixating polymerization, comprise an irradiation system able to irradiate the area comprising and surrounding the relief structure, either being said addressable irradiation system or an additional irradiation system.

In the case of heat inducible fixating polymerization, when the polymerizable composition of the medium comprises a heat inducible polymerization initiator, such fixating means may comprise a heating source able of heating to a temperature at which said heat inducible polymerization is induced.

In cases where the above mentioned heating source, used for heating the medium to facilitate said monomer diffusion, is also capable of heating the area comprising and surrounding the relief structure to a polymerization inducing temperature, said heating source may constitute the fixating means for fixating said developed tactile relief structure.

A printer device according to the present invention may also comprise coating means for coating a substrate with a polymerizable composition to obtain a medium suitable for use in the printer device. Such coating means may, for instance, comprise a container capable of holding the polymerizable composition, which container comprises or is connected to means for coating, for example doctor blade coating, a substrate with a polymerizable composition or means for casting a polymerizable composition on a substrate. This enables the use of e.g. ordinary paper or other substrates in the printer device, as the device can produce a suitable medium for use in the device from this substrate. In a second aspect, the present invention relates to a disposable or reusable cartridge capable of holding a polymerizable composition comprising a stationary phase component, polymerizable monomers and a radiation inducible polymerization initiator. The cartridge can be connected to, or optionally comprise, coating means capable of coating the polymerizable composition onto a substrate to provide a medium for providing tactile information.

In a third aspect, the present invention further relates to a medium for presenting information as a tactile relief structure, comprising a substrate which at least on one side is coated with a polymerizable composition comprising a stationary phase component, polymerizable monomers and a radiation inducible polymerization initiator. The stationary phase component, preferably comprising a polymer, forms an essentially stationary phase on the substrate and the monomers can diffuse through the stationary phase.

The radiation inducible polymerization initiator may be a UV-light inducible polymerization initiator, as this minimizes the risk for accidental polymerization if the polymerizable composition is exposed to ambient light.

The polymerizable composition of the present invention may further comprise a heat inducible polymerization initiator. This allows for heat induced polymerization in the medium, which may be used to fixate a developed surface relief by depleting the composition of polymerizable monomers. In a fourth aspect, the present invention relates to the use of a polymerizable composition, comprising a stationary phase, polymerizable monomers and a radiation inducible polymerization initiator, as a coating on a substrate, to provide a medium for presenting information as a tactile relief structure. In a fifth aspect, the present invention also relates to a method for developing tactile information on a medium comprising a substrate, on at least one side coated with a polymerizable composition comprising a stationary phase component, polymerizable monomers and a radiation inducible polymerization initiator. The method comprises irradiating an addressed area of a polymerizable composition on a medium to effect polymerization in the addressed area. The polymerization effects polymerization induced diffusion of polymerizable monomers towards said irradiated addressed area of said medium, whereby a tactile relief structure develops in said addressed area of said medium.

The method may further comprise heating at least part of the medium to facilitate the polymerization induced diffusion of monomers in said part. The method according to the present invention may also comprise fixating the developed relief structure. The fixating is effected by depleting an area surrounding a developed profile structure of polymerizable monomers, thus stopping the polymerization driven diffusion of monomers, which diffusion causes the profile structure to develop. Depending on the medium used in this method, this may be performed in one of several different manners.

One example of a method for fixating the developed relief structure, when polymerization in the medium is heat inducible, is to heat the medium to effect polymerization and thus polymerize remaining monomers, thus stopping the polymerization induced diffusion and fixating the developed relief structure. Another example of a method for fixating the developed relief structure, when polymerization in the medium is radiation inducible, is to uniformly irradiate the medium to deplete it of polymerizable monomers, thus stopping the polymerization induced diffusion and fixating the developed relief structure.

The use of photo -embossing for producing tactile information of a surface allows printing of tactile information without the need for a master stamp, allowing economically feasible printing of single sets of tactile information. Furthermore, the resolution of the tactile information is mainly limited by diffraction of the irradiation. Moreover, the printed tactile information is an integrated member of the surface material of the medium, not being discrete drops of matter disposed on the surface, thus yielding information more resistant to mechanical influences.

BRIEF DESCRIPTION OF THE DRAWINGS Further details and advantages of the present invention will now be described in the following detailed description preferred embodiments, wherein embodiments of the invention will be described, with reference to the enclosed drawings. The drawings are illustrative only and are not drawn to scale. Thus, some dimensions and distances in the drawings may be highly exaggerated in respect to other dimensions and distances, respectively.

Figure 1, a-c, shows three surface relief structures obtained by a photo- embossing technique.

Figure 2 is a schematic view of an embodiment of a printer device according to the invention. Figure 3 is schematic view of a second embodiment of a printer device according to the invention.

Figure 4 illustrates, in cross sectional view, a medium according one embodiment of the present invention before being exposed to radiation.

Figure 5 outlines a method of printing tactile information on the medium in Fig. 4.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

One embodiment of a printer device according to the present invention, as schematically shown in Fig.ure 2, comprises an addressable irradiation system, comprising a control unit 11, a UV-lamp 12 and a programmable liquid crystal mask 13.

The mask 13 comprises a liquid crystal (LC) layer 14 sandwiched between a pair of polarizers 15 and a pair of patterned electrodes 16. The liquid crystal layer 14 in the mask 13 is patterned into several domains, and the LC-layer in each domain can be independently controlled as to allow or block light from passing through the mask in that domain.

The control unit 1 1 is capable of receiving information, representing an image to be printed as tactile information, and transforming this into coordinates and intensity values. The coordinates are utilized to program the LC-mask 13, and the intensity data is utilized to control the intensity of the lamp 12, so that the desired addressed area of a medium 18 is irradiated with a desired dose of radiation.

Another embodiment of the present invention, as schematically shown in Fig.ure 3 comprises a control unit 21, a movably arranged radiation source 22, a heating source 23 and motorized rolls 24 for positioning the medium 25. The radiation source 22 is arranged on a position controllable sledge 26 which is movable along the direction of a bar 27. The medium 25 is movable in a direction essentially perpendicular to the direction of the bar 27 and its position is controlled by a set up of motorized rolls 24 being able to feed the medium 25. The control unit 21 controls the heating source 23, the position of the radiation source 22, the intensity of the radiation source and the position of the medium 25, via the motorized rolls 24. The set up is analogue to the set up of a conventional ink jet printer.

Instead of the sledge in Fig. 3, the irradiation system may comprise a source- and-sledge setup in which the location of the medium is fixed and sledge is able to move along the length and the width of the medium. Further embodiments of addressable irradiation systems may be used in printer devices according to the present invention. For example, the source-and-sledge setup shown in Fig.ure 3 above may be replaced by an array of intensity controllable radiation sources, which array covers essentially the size of the medium in a direction essentially perpendicular to the direction of movement of the medium. The addressable irradiation system may also comprise a radiation source and a system of scanning mirrors. The radiation from the radiation source is directed to the scanning mirror system, which re-directs the radiation towards the addressed area of the medium.

As realized by those skilled in the art, any addressable irradiation system suitable for irradiation of an addressed area of a medium may be used in printer devices according to the present invention.

The type of radiation irradiated by the radiation source depends on the type of radiation that is suitable for activating the radiation inducible polymerization initiator, and includes, for example, sources of γ-radiation, electrons, UV-light and visible light.

Sources of UV-light suitable for use in the present invention includes for example UV-diodes, UV-lasers or other sources of UV-light, such as broad spectrum lamps, e.g. a mercury lamp, provided with a UV-bandpass filter.

A printer device according to the present invention further comprises a heating source arranged to heat at least a part of the medium comprising an addressed area, after said addressed area has been irradiated by the radiation source. In the embodiment shown in Fig.ure 2, the heating source 17 is a high- resistivity layer, on which the medium 18 is placed. The layer 17 comprises several domains which independently may be activated by electricity to heat parts of the medium 18 after completion of an irradiation thereof. In the device shown in Fig.ure 3, the heating source comprises an infrared line source 23 arranged essentially perpendicular to the direction of movement of the medium and spanning essentially the width of the medium. The line source 23 is positioned in a location downstream the radiation source 22 in respect to the direction of movement of the medium, thus being able to heat the medium 25 to the desired temperature as the medium moves past the infrared line source 23. The infrared heating source may also be such a source capable of irradiating essentially the entire medium after completion of an irradiation step.

Other heating sources suitable for heating at least a part of the medium may also be used in the printer device according to the present invention.

Furthermore, the printer device according to the present invention is not limited to the above combinations of irradiation system and heating source, and any suitable combination thereof may be used.

It is to be understood that the herein described embodiments of the present invention is provided only for illustrative purposes, and are not intended to limit the scope of the invention, for example, the printer device of the present invention may also comprise a device for coating a substrate with a polymerizable composition to produce a medium of the present invention.

A printer device according to the present invention may further also comprise means for printing information to be visible on the medium. Such means comprises the necessary parts of for example a laser printer, a dot matrix printer or an ink jet printer. The visible information may be printed on one of the surfaces of the medium, the same and/or opposite surface of the medium as the tactile information, and next to and/or on top of the tactile information. Optionally, the visible information may be printed on the surface of the substrate, before that surface is coated with the polymerizable composition.

A medium suitable for use with the printer devices in Fig. 2 and Fig. 3 is shown in Fig. 4. The illustrated medium comprises a paper substrate 31, on one side coated with a polymerizable composition 32.

The polymerizable composition comprises a stationary phase component, preferably a polymer, polymerizable monomers and a radiation inducible polymerization initiator and a heat inducible polymerization initiator. Substrates suitable for use in a medium of the present invention comprise substrates of paper, cardboard, plastic, glass, wood, metal and other materials desirable to print tactile information on.

Polymerizable compositions suitable for use in a medium of the present invention comprises such polymerizable compositions that may be coated on a substrate as described above.

Polymers suitable for use in the polymerizable composition of the present invention include, but are not limited to, poly(benzylmethacrylate), poly(phenylmethacrylate), poly(methylmethacrylate), poly(/-butylmethacrylate), polystyrene, poly(α- methyl styrene), poly(biphenyl acrylate), poly(vinylchloride), poly(vinylidene dichloride), poly(ethylene terephthalate), poly(naphthalene terephthalate), poly(bisphenol-A carbonate), and any suitable combination thereof in the form of polymer blends or in the form of copolymers or block-copolymers.

Polymerizable monomers suitable for use in the polymerizable composition of the present invention include, but are not limited to, pentaerythritol tetraacrylate, trimethylol propane triacrylate, trimethylol propane trimethacrylate, ethyl hexylacrylate, hexanediol diacrylate, tripropylene glycol diacrylate, ethoxylated bisphenol-A diacrylate, and any suitable combination thereof. These materials can be cured with free-radical initiators.

It is also possible to base the system on other type of polymerization mechanisms, for instance a cationic polymerization mechanism. In that case monomers with a vinyl ether reactive groups can be selected, such as trimethylol propane trivinyl ether, or an epoxide reactive group, such as cyclohexeneoxide and its derivatives or diglycidyl ether of bisphenol-A.

Radiation inducible polymerization initiators for use in the polymerizable composition of the present invention include, but are not limited to, UV-light inducible initiators, visible light inducible initiators, combinations of UV-light inducible acrylates with a sensitizer molecule active in the visible part of the spectrum, etc.

UV-light inducible polymerization initiators suitable for use includes such compounds as 2,2-dimethoxy-l,2-diphenylethan-l-one, 2-benzyl-2-dimethylamino- 1 -(4- morpholinophenyl)-butanone-l and bis-(2,4,6-trimethylbenzoyl)-phenylphosphineoxide.

In the case of a cationic polymerization mechanism also a so-called cationic photoinitiator needs to be selected, such as iodonium-(4-methylphenyl)[4-(2- methylpropyl)phenyl]-hexafluorophosphate ( 1 -). In the case of γ-radiation or electron beam radiation no photo initiator is necessary. In that case the monomers and/or polymers may generate the reactive particles by absorbing the high-energetic radiation and subsequent partial degradation.

The polymer forms an essentially stationary phase in the composition, and at room temperature, the polymerizable composition forms a non-tacky layer on the substrate and the polymer does not allow essentially any polymerization induced monomer diffusion in the coating. However, when at a temperature well above room temperature, about 6O⁰C, the viscosity of the polymerizable composition is reduced, so that polymerization induced monomer diffusion is facilitated. The stationary phase, the monomers and initiators used and the proportions thereof in the polymerizable composition of the present invention is chosen so that the monomer diffusion mobility through the stationary phase is low at a first temperature, thus essentially not allowing any polymerization induced diffusion of monomers at said first temperature, while the monomer diffusion mobility in the polymerizable composition is high enough at a second temperature, higher than said first temperature, to allow polymerization induced diffusion of monomers at this second temperature.

One convenient way to achieve this is to select the stationary phase polymers from the classes that have their glass transition temperature well above the first temperature, for example at about 6O⁰C when the intended first temperature is about 15-30⁰C. The added monomer normally has a plasticizing effect lowering the glass transition temperature of polymerizable composition. Preferably, the glass transition temperature of the polymerizable composition is around or above the first temperature.

Preferably, the polymer is a glassy material that has its transition to the liquid, high diffusion mobility phase, at elevated temperatures. Upon irradiation at the first temperature, the mobility of the monomers through the stationary phase is low, preferably with a diffusion constant of the monomer smaller than 10^"12 m²/s. Upon heating, the diffusion constant of the monomer increases to values higher than 10^"12 m²/s, e.g. 5 * 10^"10 m²/s.

One example of such a polymerizable composition comprises 60 wt% polybenzylmethacrylate, 38 wt% pentaerythritol tetra-acrylate and 2 wt% 2-benzyl-2- dimethylamino-l-(4-morpholinophenyl)-butanone-l, and another example of such a mixture comprises 55 wt% polymethylmethacrylate, 35 wt% trimethylolproprane triacrylate, 8 wt% hexanedioldiacrylate and 2 wt % 2,2-dimethoxy-l ,2-diphenylethan-l-one.

Examples of heat inducible polymerization initiators include, but are not limited to, benzoylperoxide and dicumylperoxide. The choice of heat inducible polymerization initiator is dependent on the content of the polymerizable composition and the temperature at which the heat induced polymerization is intended, and will be apparent for those skilled in the art.

A medium according to the present invention may further comprise a protective film arranged on top of the polymerizable composition, thus further protecting the composition from mechanical influences, such as for example scratches, and further preventing mediums from adhering to each other. The protective film is preferably a thin polymeric film.

Further, the film may be transparent to the radiation effecting radiation induced polymerization in the polymerizable composition, thus allowing the protective film to be left on the medium through out the process of printing tactile information on the medium.

The medium can be transparent, allowing printing of visible information on the side of the substrate not facing the polymerizable composition, thus allowing the visible information to be seen also on the side of the substrate on which the tactile information is located, through the substrate and the polymerizable composition.

The function of the devices in Fig. 2 and 3, for printing tactile information on the medium in Fig. 4 will now be described, and is schematically also shown in Fig.ure 5.

First, as schematically shown in Fig. 5A, an addressed area of the medium is irradiated at a first temperature (Ti), at which the monomer diffusion mobility is low. This activates the radiation inducible polymerization initiator in the addressed, irradiated area and thus, effects local polymerization, but due to the low diffusion mobility the polymerization is retained in the irradiated area.

Second, as schematically shown in Fig. 5B, the an area of the medium comprising and surrounding the irradiated area is heated to a second temperature (T₂, higher than Ti), at which the monomer diffusion mobility is higher. Thus polymerization induced diffusion towards the irradiated addressed area is facilitated in the heated area. This diffusion of monomers causes a local volume increase, and thus a relief structure develops in said addressed area of said medium. Third, as schematically shown in Fig. 5C, the developed relief structure is fixed. This is accomplished by heating the medium to a third temperature (T₃, higher than T₂) at which the heat inducible polymerization initiator is activated. Thus essentially all remaining polymerizable monomers are polymerized and the polymerization induced monomer diffusion is stopped, thus fixating the image. The first temperature preferably is around room temperature such that the localized radiation can take place under ambient conditions. The second temperature should be such that the monomer diffusion process does not occur at ambient conditions at relatively high temperatures but that it proceeds at relatively mild and easy-to-handle temperatures, such as about 5O⁰C or higher.

Claims

CLAIMS:

1. A printer device for printing information as a tactile relief structure on a medium (18; 25) comprising a substrate (31), which on at least one side is coated with a polymerizable composition (32) comprising a stationary phase component, polymerizable monomers and a radiation inducible polymerization initiator, said printer device comprising: - an addressable irradiation system (11, 12, 13, 14, 15, 16; 21, 22, 24, 26, 27), arranged to irradiate an addressed area of the polymerizable composition when the medium is located in said device such that radiation induced polymerization is induced in said addressed area and polymerization induced diffusion of polymerizable monomers towards said . addressed area is induced, to develop a tactile relief structure in said composition.

2. A device according to claim 1, further comprising a heating source (17; 23) arranged to heat at least part of said irradiated area of said medium, to facilitate said polymerization induced diffusion.

3. A device according to any of the preceding claims, wherein said irradiation system is arranged to provide said medium with a variable intensity of radiation to provide a tactile relief structure with variable height.

4. A device according to any of the preceding claims, wherein said addressable irradiation system comprises a radiation source (12) and a mask (13, 14, 15, 16), said mask being arranged between said radiation source and said medium.

5. A device according to any of the claims 1 to 3, wherein said addressable irradiation system comprises a radiation source (22) and a position controlling system (24, 26, 27), which is arranged to position said radiation source in relation to said medium so that radiation from said radiation source irradiates said addressed area.

6. A device according to any of the claims 1 to 3, wherein said addressable irradiation system comprises a radiation source and at least one mirror, wherein said at least one mirror is arranged to direct radiation from said radiation source onto said addressed area.

7. A device according to any of the preceding claims, further comprising means for fixating said developed tactile relief structure.

8. A device according to claim 7, wherein said heating source (17; 23) constitutes said means for fixating said developed tactile relief structure.

9. A device according to any of the preceding claims, further comprising means for coating a substrate with a polymerizable composition comprising a stationary phase component, polymerizable monomers and a radiation inducible polymerization initiator to obtain a medium suitable for use in said device.

10. A cartridge for use in a printer device according to claim 1 , comprising a container holding a polymerizable composition comprising a stationary phase component, ^; polymerizable monomers and a radiation inducible polymerization initiator, said container being adapted for connection to a coating means for coating a substrate with said composition.

11. A medium for presenting information as a tactile relief structure, comprising substrate (31) which at least on one side is coated with a polymerizable composition (32) comprising a stationary phase component, polymerizable monomers and a radiation inducible polymerization initiator.

12. A medium according to claim 11, wherein said stationary phase component comprises a polymer.

13. A medium according to any of the claims 11-12, wherein said radiation inducible polymerization initiator is UV-light inducible.

14. A medium according to any of the claims 11-13, wherein said polymerizable composition further comprises a heat inducible polymerization initiator.

15. Use of a composition, comprising a stationary phase component, polymerizable monomers and a heat inducible polymerization initiator, as a coating on a substrate to provide a medium for presenting information as a tactile relief structure.

16. A method for developing information as a tactile relief structure on a medium comprising a substrate, on at least one side coated with a polymerizable composition comprising a stationary phase component, polymerizable monomers and a radiation inducible polymerization initiator, said method comprising: - irradiating an addressed area of a polymerizable composition on a medium to effect polymerization in said addressed area and induce polymerization induced diffusion of polymerizable monomers towards said irradiated addressed area of said medium, whereby a tactile relief structure develops in said addressed area.

17. A method according to claim 16, further comprising heating at least part of said medium, said part comprising at least part of said addressed area, to facilitate said polymerization induced diffusion.

18. A method according to any of the claims 16-17, wherein said polymerizable composition further comprises a heat inducible polymerization initiator and wherein said method further comprises: heating said at least part of said medium to a temperature at which said heat inducible polymerization initiator is activated to effect polymerization in said polymerizable composition, thereby depleting said part of said medium of polymerizable monomers and fixating said developed tactile relief structure.

19. A method according to any of the claims 16-17, further comprising irradiating at least part of said medium to the medium to effect polymerization in said polymerizable composition, thereby depleting said part of said medium of polymerizable monomers and fixating said developed tactile relief structure.