FR2810920A1 - Thermal transfer printing, uses modulated light to adhere powder to face of ribbon for transfer when ribbon is heated - Google Patents

Abstract

The thermal printer sprinkles powder (16) on the pigmented face of the thermal ribbon (1). Light (8) is modulated (5) and projected (12) onto the back of the ribbon, and powder adheres to the ribbon depending on illumination at each point. The ribbon is passed between a heated roller (21') and a pressure roller (22) so the image on the ribbon is transferred to a strip (19).

Description

-1 - State of the art The current transfer printing process consists of

  locally heat a thermal transfer ribbon composed of a thin film previously covered with a thin layer of wax or resin associated with pigments. This tape brought to a temperature of the order of about a hundred degrees adheres to another support if the latter is in physical contact face down. The wax plus pigments structure is designed to easily separate from its base support and preferentially hang on the various paper or plastic supports in contact with the ribbon on the pigment side. The resolution of the images obtained by such a process is limited by the technology of the heads.

  thermal (dimensions of an elementary cell 43 x 43 pm) and the thickness of the ribbon.

  This method does not make it possible to obtain images with gray level in an analogical manner, it is used for printing characters or bar code, that is to say two physical states of the white or black receiving medium. This is why its use is limited to consumer printers and the personalization of code labels.

  associated bars and plastic cards.

  OBJECT OF THE INVENTION The present invention overcomes this drawback by recording an image on the thermal transfer ribbon and then transferring this image to a receiving medium so as to view the image with maximum contrast and quality.

  According to the invention, a recording method is proposed (claims 1,3 and 17).

  This method is used by a recorder ... (claims 22 and 24).

  The invention also relates to a spatial modulator ... (claim 35).

2-

Description

  The characteristics and advantages of the invention will appear more clearly on reading

  of the description, given by way of example, and of the figures relating thereto which represent:

  - Figure 1, a cross section of a thermal transfer ribbon at rest; - Figure 2 (a), the recording on the ribbon of the data by modulation of a thermal energy source; - Figure 2 (b), recording with the use of a second energy source; - Figure 3 (a), the recorder according to the first variant of the invention; - Figure 3 (b), concentric deflection spatial modulator - Figure 4 (a), recording with the use of a blotter; - Figure 4 (b), recording with the use of a powder; - Figure 4 (c), recording with the use of a second ribbon comprising a support covered with a layer of wax or resin associated with ferromagnetic particles; - Figure 4 (d), recording with the use of a ribbon comprising a support covered with a layer of wax or pure heat-shrinkable resin; - Figure 5, the transfer of recorded data from the tape to the recording medium according to the invention; - Figure 6, the gray level printer by thermal transfer according to the invention; In the various figures, the corresponding elements are designated by the

same benchmarks.

  Figure 1 shows an example of a thermal transfer ribbon 1 such as that used by the invention. It consists of a smooth and thin support 2 (polyester film of about 5 μm thick). This support 2 is coated on one of its faces with a thin film 3 of wax or resin associated with pigments (a few pm), by

example of carbon powder.

  Use of commercial transfer tape like the one described above

  provides a greyscale thermal print at low cost.

  FIG. 2 (a) shows an example of a recording method according to the invention in which a source (located in the electromagnetic spectrum between 0.2 and 3 μm) of modulated thermal energy 6 modifies the state transfer ribbon 1 according to its energy distribution. The beam of modulated thermal energy 5 absorbed by the pigments brings the layer of wax or resin 3 to melting temperature. In an exemplary embodiment, the surface of the ribbon 1 coated with wax associated with black pigments which was mat and rough becomes shiny and smooth on impact.

  modulated thermal energy beam 5 (by a phenomenon of surface ablation).

  It is thus easy to reproduce an image on this type of ribbon 1. The phenomenon observed is dependent on the type of pigment used (black, colored, invisible, organic or metallic, etc.). The possible use of numerous pigments allows the manufacture of tamper-proof cards (with holograms, data visible under infrared, ultra violet or X-ray lighting, etc.), security badges (circuit printing

for microwave badges) ...

  Depending on the absorbency of the pigment used and to reduce the thermal energy to be projected onto the tape, a variant of the recording method according to the invention provides for bringing the tape to a temperature slightly below the melting point of the wax. or resin. This temperature will be referred to as the threshold temperature in the remainder of this document. It is obtained by means of a second source of thermal energy 7, such as radiation or a continuous thermal background or a heating plate for example. A modulated beam 5 is added to it as shown in Figure 2 (b). The exposure time then becomes very short with a modular source 8 of around 100 to a few hundred Watts. The continuous bottom 7 can be provided by a source of 100 to a few kilowatts. The exposure time is a few

  tenths of a second for a commercial ribbon.

  FIG. 3 (a) shows a first variant of the recorder 14. It includes a source of thermal energy to be modulated 8. This source 8 can be a light source such as, for example, a white light source (incandescent lamp, halogen ...) or a monochromatic light source (scanning laser ...) or a row of scanning diodes. According to the source 8, the thermal energy beam to be modulated 9 coming from the latter crosses the spatial modulator 11 containing the image to be recorded to form a modulated thermal energy beam 5. In the case of the white light source 8, a collimator 10 directs the light beam 9 so that the source 8 uniformly illuminates the spatial modulator 11. This spatial modulator 11 is either a static image on a transparent film, or a system of concentric deflection of circles coplanar (see Figure 3 (b)), either an LCD matrix, or an active matrix of micro-mirrors addressable by electronic means so as to modulate point by point the light intensity. This energy passes through the concentric deflection system or the active matrix or is reflected on the mirror matrix so as to form a luminous object then projected onto the ribbon

  heat transfer using a lens 12.

  A heating system 7 by radiation or by contact is placed on the other side of the strip 1. This heating system 7 preferably by radiation can be placed on the side of the modulated beam 5 in certain cases to add up the energies. The exposure time of the image projected on the ribbon is controlled. This exposure time control device (not shown in the diagram) can be, for example, a mechanical shutter or more simply a control device

of the spatial modulator.

  Mechanical means 29 make it possible to arrange the ribbon in the plane of the image. They allow the tape 1 to be advanced step by step by a distance greater than the dimension of the image in the longitudinal direction so as to record

  successively different images according to the length of the ribbon 1.

  In a second variant of the recorder 14, the projector 13, comprising the source to be modulated 8, the collimator 10, the space modulator 11 and the objective 12, is replaced by a source of thermal energy 6, such as a scanning laser, a row of scanning diodes or an array of diodes; this projector is directly modulated by a signal corresponding to the image to be recorded to constitute the point image

per point on the ribbon 1.

  FIG. 3 (b) shows a variant of the spatial modulator 11, that is to say a system of concentric deflection of coplanar circles composed of two discs, each provided with a fenestration. The window of each disc has the shape of a spiral which originates from the center of the disc and collapses at its periphery. The two discs are motorized independently by means of a stepping motor. The first has a clockwise direction. The second has a counterclockwise rotating direction. The superposition of the two discs, completely exposed, allows the crossing of the modulated thermal energy at the point of intersection of the two windows. Incrementing a step in the respective rotational direction of the two discs allows the radial displacement of the point of intersection of the two windows. The rotation of the mobile assembly allows the circular excursion of this point. The modulator, as described, scans point by point the data of the image to

  record and cover the entire surface of this image.

  Such a tape 1 thus recorded can be used to transfer the recorded image to a receiving medium 19 as will be described later. However, the recording process can be supplemented by the improvements of FIGS. 4 (a)

to 4 (d).

  In the variant of FIG. 4 (a), the material is a paper 15 having a high absorbency, of the blotting type, such as the paper used in inkjet printing such as, for example, high resolution office printing. An acoustic wave propagating in the solid medium formed by the paper and ribbon couple 1, assisted by a curette-type tool, scrapes the surface of the ribbon 1 during the recording which results in the detachment of the layer of wax or resin associated with the pigments of the parts exposed to the modulated beam 5, and its deposition on the absorbent material. The separation of the tape 1 and the absorbent material is done either immediately or after a cooling time. The positive image thus recorded on the transfer ribbon 1 can be directly transferred to the support.

receiver 19.

  In the variant of FIG. 4 (b), the material is a powder 16, such as preferably ferrite powder or natural magnesium silicate (talc) ... A simple means to facilitate the deposition of the powder 16 on ribbon 1 on the pigmented side for example,

  is to electrify the resin layer of the ribbon 1 (by friction, by contact, by piezo

  electricity, or by electro-static fields ...) on its side 2 before and during the recording or in the case of the wax by the mixing and the projection of the powder before and during the recording of the image. The powder 16, the grain of which has a dimension of the order of μm, is amalgamated and absorbs the layer of wax or pigmented resin of the ribbon 1 at melting temperature, preferably on the areas exposed to thermal energy, while unexposed areas do not retain grains of powder. The powder 16 which is not amalgamated on the areas not exposed to thermal energy is then removed. The positive image thus recorded on the transfer ribbon 1

  can be directly transferred to the receiver support 19.

  In the variant of FIG. 4 (c), a ribbon 1 and a second ribbon 17 are used, composed of a support and a film of wax or resin associated with ferrite particles. The ferrite side of the second tape 17 is applied against the pigmented side of the heat transfer tape 1 recording. The modulated beam 5 containing the image to be recorded is projected onto the assembly comprising these two ribbons 1 and 17, joined either by an electrostatic field or by a magnetic field or by an electromagnetic field. The exposed area of the wax or resin film 3 associated with the

  pigments of the thermal transfer ribbon 1 is brought to melting temperature.

  Either the pigments of ribbon 1 are attached to the wax or the resin associated with the ferrite particles of the second ribbon 17. Either the ferrite particles of ribbon 17 are bonded to the wax or the resin associated with the pigments of ribbon 1. The two ribbons are then separated either immediately or after a certain time of cooling of the assembly. The positive image thus recorded on the transfer tape 1 can be

  directly transferred to the receiver support 19.

  In the variant of FIG. 4 (d), a ribbon 1 and a second ribbon 18 are used, composed of a support and a film of wax or heat-shrinkable resin or comprising nanocavities. The modulated beam 5 containing the image to be recorded is projected onto the assembly comprising these two adjoining ribbons 1 and 18. The area exposed to the thermal energy of the wax or resin film 3 associated with the pigments of the thermal transfer ribbon 1 is brought to melting temperature. The pigments of the ribbon 1 adhere to the wax or the heat-shrinkable resin of the ribbon 18, by the surface tension effect combined with the retractability effect, they unhook from the support 2 of the ribbon 1 and migrate on the support of the ribbon 18. The two ribbons are then separated either immediately or after a certain time of cooling of the assembly. The positive image thus recorded on the transfer tape 1 can be

  directly transfer to the receiver support 19.

  FIG. 5 shows an example of a device 22 for transferring the image recorded on the thermal transfer ribbon 1 to the receiving support 19, for example paper or plastic support. The direct transfer of this image recorded on the receiving support 19 is carried out by hot contact with an adjustable pressing according to the receiving support using, for example, a preferably heating press or heating rollers 21 ′ and 21 ". The contacting and the diffusion of heat can be carried out either by a common device, or by separate devices.

  heat diffusion which may result from heat induction in the ribbon 1.

  FIG. 6 shows an example of printer according to the invention, composed of a

  recorder 14 and a transfer device 22.

  A device 27 sprinkles powder 16 on the pigmented face of the ribbon.

  1 virgin heat transfer from a reel 23 of 1 virgin transfer ribbon.

  A light source 8 is collimated so as to uniformly illuminate the spatial modulator 11. The modulated light beam 5 is projected onto the support face 2 of the thermal transfer ribbon 1 through the objective 12. After recording the image on the ribbon 1, a device 28 (squeegee, for example) removes the non-amalgamated powder with the pigment and wax or resin mixture coming from areas not exposed to the thermal energy of the thermal transfer ribbon 1. A mechanical device 29 makes it possible to have thermal transfer ribbon 1 in the image plane for recording. It then allows you to place the ribbon1 containing the image

  recorded on the pigmented side 3 against the receiver support 19 for the transfer.

  The assembly comprising the tape 1 recorded and the receiving support 19 is then between a heating roller 21 'placed against the support 2 of the tape 1 and a pressure roller 21 "placed against the receiving support 19. The action of these two rollers facilitates the transfer of the pigments constituting the image of the ribbon 1 to the receiving support 19. The receiving support 19 comes from a reel 25 of receiving support 19 which is blank and is wound around a reel 26 after the transfer of the image. The transfer ribbon

  thermal 1 used is finally wound on the coil 24.

  During the description above, the example chosen to represent the invention is

  that of printing an image. The invention can in reality apply to any type of data format: handwritten or typed texts, reproductions, engravings, photographs, holograms ... The transfer of the recorded image is made - 8 - to n ' any type of support and is not limited to paper or plastic supports

  mentioned in the description above.

-9

Claims (54)

  1. Method for recording data on a thermal transfer ribbon (1), comprising a support (2) covered with a film of wax or resin (3) associated with pigments, characterized in that a beam of thermal energy modulated (5) by data to be recorded is projected onto the ribbon (1) so as to   spatially modify the state of the ribbon (1) according to the energy distribution.   2. Recording method according to claim 1 characterized in that the thermal energy from a first modulated thermal energy source (6) is absorbed by the pigments in the exposed areas and carries the layer of wax or   resin (3) at melting temperature.   3. Recording method according to one of claims 1 or 2   characterized in that the recording part of the tape (1) is brought to a threshold temperature, and that the said modulated thermal energy beam (5) makes it possible to pass the temperature of the layer of wax or resin (3) of the exposed areas of the tape (1) of   said threshold temperature at the melting temperature of the wax or of the resin.   4. Recording method according to claim 3 characterized in that this threshold temperature is obtained by a second source of thermal energy (7) (heating system by radiation or by contact or thermal continuous background or hotplate...).   5. Recording method according to one of claims 3 or 4   characterized in that this threshold temperature is obtained by a second source of thermal energy (7) of approximately 100 to a few kilowatts, and that the first source of thermal energy to be modulated (8) is approximately 100 to several hundred from Watts. The power varies according to the printing speed, the pigment used, and the   dimension of the image to be recorded. - 10 -   6. Recording method according to one of claims 1 to 5   characterized in that the first source of thermal energy is a light source. 7. A recording method according to claim 6 characterized in that the light source to be modulated (8) is a white light source. Halogen lamp type. 8. Recording method according to claim 6 characterized in that the modulated light source (6) is a modulated laser which scans the surface tape recording (1).   9. Recording method according to claim 6 characterized in that the modulated light source (8) is a matrix or a row of diodes to variable powers.   10. Recording method according to claim 9 characterized in that   the row of diodes scans the recording surface of the tape (1).   11. Recording method according to one of claims 1 to 7   characterized in that the data to be recorded modulates the energy source   thermal (8) using a spatial modulator (11).   12. Recording method according to claim 11 characterized in that the spatial modulator (11) comprises non-modifiable data, such as a still image.   13. Recording method according to claim 11 characterized in that   that the spatial modulator (11) is controllable.   14. Recording method according to claim 13 characterized in that the spatial modulator (11) is either a concentric coplanar deflection system, either an LCD matrix, or a matrix of micro mirrors addressable by means - 11 -   electronic so as to modulate point by point the intensity of the beam (9) coming from the thermal energy source (8). In the case of total matrix irradiation, it is necessary to neutralize the phenomenon of thermal propagation by irradiation, in the ribbon (1). A progressive amplification from the center to the periphery (of thermal energy) is summed to the initial thermal energy of the image to be projected. This amplification equalizes the distribution of thermal energy, and inhibits the undesirable physical reaction by compensating for the value of each of the points according to its position in the plan which composes the image.   15. Recording method according to one of claims 1 to 14   characterized in that the time of exposure of the ribbon (1) to the energy beam   modulated thermal 5 is controlled.   16. Recording method according to claims 1 to 15 characterized in   what: - either the thermal transfer ribbon (1) comprises: * a support (2), such as a polyester film, about 5 μm thick * a film of wax or resin (3) of a few μm thick associated with pigments, such as black pigments (carbon powder, for example)   or colored or invisible in daylight or metallic or organic .. ..   - either the thermal transfer ribbon (1) is a commercial ribbon - or a ribbon composed of a support covered with a layer of wax or resin   heat-shrinkable (or comprising nano-cavities).   17. Recording method according to one of claims 1 to 16   characterized in that a material capable of amalgamating with the mixture of wax or resin pigments at melting temperature is deposited on the pigmented face of the thermal transfer ribbon (1). Either in the case of the resin by negative electrification (by friction, by contact, by piezoelectricity, or by an electrostatic field ...) before and during recording, or in the case of wax by mixing and the projection of the powder before and during the recording of the image. This material, amalgamated with the mixture of wax or resin and pigments, this being in the areas exposed to thermal energy, cannot be removed after   data recording on the thermal transfer ribbon (1). - 12 -   18. Recording method according to claims 1 to 16 characterized in   what this material consists of is a blotting-type paper (15), such as, for example, high-resolution office printing paper, assisted by a scraping tool and an acoustic wave propagating in the solid medium.   19. Recording method according to claims 1 to 17 characterized in   that this material consists of a powder (16) of a dimension of the order of pm.   20. Recording method according to claims 1 to 16 characterized in   that this material consists of a ribbon (18), which comprises a support covered with a layer of wax or of heat-shrinkable resin or comprising nano-cavities, positioned such that its support is outside the set including this ribbon (18)   and the thermal transfer ribbon (1).   21. Recording method according to claims 1 to 16 characterized in   that this material consists of a second ribbon (17) composed of a support covered with a film of wax or resin associated with ferromagnetic particles (ferrite) the ferrite face of which is affixed to the pigmented face of the   first thermal transfer ribbon (1).   22. Data recorder (14) on a thermal transfer ribbon (1), comprising a support (2) covered with a film of wax or resin (3) associated with pigments, characterized in that it comprises a first modulated thermal energy source (6) and a thermal transfer ribbon (1) located downstream of the source (6), the characteristics of the modulated thermal energy source (6) being such that it comes spatially modify the state of the thermal transfer ribbon (1) according to its distribution.   23. Recorder (14) according to claim 22 characterized in that the characteristics of the modulated thermal energy source (6) are such that the layer of wax or resin (3) of the zones of the thermal transfer ribbon (1) exposed to thermal energy by said source (6) is brought to melting temperature by the   through pigment or ferrite. - 13-   24. Recorder (14) according to one of claims 22 or 23 characterized in   that it comprises a second source of thermal energy (7) whose characteristics are such that the recording part of the tape (1) is brought to a threshold temperature, and that the characteristics of said first source of thermal energy ( 6) are such that the layer of wax or resin (3) of the zones exposed to the thermal energy of the ribbon (1) passes from said threshold temperature to the melting temperature of the wax or   resin through the pigment or ferrite.   25. Recorder (14) according to claim 24 characterized in that the second source of thermal energy (7) is either a heating system by radiation or by contact, or a thermal continuous bottom, or a hot plate ...   26. Recorder (14) according to one of claims 24 or 25 characterized in   that the second source of thermal energy (7) is about 100 to a few kilowatts, and that the first source of thermal energy to be modulated (8) is about a few hundred Watts.   27. Recorder (14) according to one of claims 22 to 26 characterized in that   that the first source of thermal energy is a light source.   28. Recorder (14) according to claim 27 characterized in that the source   light to be modulated (8) is a white light source.   29. Recorder (14) according to claim 27 characterized in that the modulated light source (6) is a modulated laser which scans the recording surface of the tape (1). 30. Recorder (14) according to claim 27 characterized in that the modulated light source (6) is a matrix or a row of diodes with variable powers. - 14 -   31. Recorder (14) according to claim 30 characterized in that the   row of diodes scans the recording surface of the tape (1).   32. Recorder 14 according to one of claims 22 to 28 characterized in that   that it comprises a spatial modulator (11) between the first source of thermal energy (8) and objective (12).   33. Recorder (14) according to claim 32 characterized in that the spatial modulator (11) comprises non-modifiable data, such as a still image. 34. Recorder (14) according to claim 33 characterized in that the   spatial modulator (11) is controllable.   35. Recorder (14) according to claim 34 characterized in that the spatial modulator (11) is a system of concentric deflection of circles   coplanar, addressable by electronic means.   36. Recorder (14) according to claim 34 characterized in that the spatial modulator (11) is either an LCD matrix or a matrix of micro-mirrors addressable by electronic means so as to modulate point by point the intensity of the beam (9) from the first source of thermal energy to modulate (8).   37. Recorder (14) according to one of claims 22 to 36 characterized in that   that it includes a module for controlling the time of exposure of the ribbon (1) to the beam modulated thermal energy (5).   38. Recorder (14) according to claim 36 characterized in that the exposure time control module is either a shutter (such as a shutter   mechanical), or the control module of the spatial modulator. - 15-   39. Recorder (14) according to one of claims 22 to 38 characterized in that   that: - either the thermal transfer ribbon (1) comprises:   has a backing (2), such as a polyester film, about 5 µm thick.   * a film of wax or resin (3) a few μm thick associated with pigments, such as black pigments (carbon powder, for example)   or colored or invisible in daylight or metallic or organic .. ..   - Either the thermal transfer ribbon (1) is a commercial ribbon.   - either a ribbon composed of a support covered with a layer of wax or resin   heat-shrinkable (or comprising nano-cavities).   40. Recorder (14) according to one of claims 22 to 39 characterized in that   that it includes a material, deposited by a module (27) (for example) capable of amalgamating with the mixture of pigments and of wax or resin at melting temperature, on the pigmented side of the thermal transfer ribbon (1 ) before and during the projection of the image to be recorded, and a module (28) for example removing said non-amalgamated material, after recording the data on the thermal transfer ribbon (1). 41. Recorder (14) according to claim 40 characterized in that it comprises either a negative electrification device in the case where the support (2) of the thermal transfer ribbon (1) is covered with a layer of resin . Either a device (27) for mixing and spraying the powder in the case where the support (2) of the ribbon   of thermal transfer (1), is covered with a layer of wax or resin.   42. Recorder (14) according to claim 40 or 41 characterized in that   this material consists of a powder (16).   43. Recorder (14) according to claim 42 characterized in that the   powder (16) has a dimension of the order of a micrometer.   44. Recorder (14) according to claims 22 to 39 characterized in that   this material consists of a blotter-type paper (15). - 16-   45. Recorder (14) according to claims 39 characterized in that this   material consists of a second ribbon (18), which comprises a support covered with a layer of wax or resin, heat-shrinkable or comprising nano-cavities, positioned such that its support is outside the assembly comprising this ribbon (18) and the thermal transfer ribbon (1). 46. Recorder (14) according to claim 39 characterized in that this material consists of a second ribbon (17) composed of a support covered with a film of wax or resin associated with ferrite particles, the face of which ferritée   is affixed to the pigmented face of the first thermal transfer ribbon (1).   47. Recorder (14) according to one of claims 22 to 43 characterized in that   that it comprises mechanical means (29) capable of placing the ribbon (1) in the map of the data to be recorded.   48. Recorder (14) according to one of claims 22 to 44 characterized in that   that these mechanical means (29) are capable of advancing the ribbon (1) step by step from a determined distance.   49. Method of transfer to a recorded data medium, characterized in that the data are spatially recorded on a thermal transfer ribbon (1) comprising a medium (2) covered with a film of wax or of resin associated with pigments (3), and that the transfer takes place directly by hot contact of the pigmented face of the thermal transfer ribbon (1) containing   The image with the receiver support (19).   50. Method for transferring data prerecorded on the thermal transfer ribbon (1) onto a receiving medium (19) by the method   recording device according to one of claims 1 to 21, characterized in that the   transfer takes place directly by hot contact of the pigmented face of the   thermal transfer ribbon (1) comprising the image with the receiving support (19).   51. Transfer device (22) on a receiving support (19), characterized in that it comprises a thermal transfer ribbon (1), comprising a support (2) covered - 17 -   a film of wax or resin (3) associated with pigments, containing spatially prerecorded data, a device for bringing the pigmented face into contact, with the receiving support (19), and a heat induction source in the   thermal transfer ribbon (1) during said contact.   52. Transfer device (22) on a data carrier, recorded on the   thermal transfer ribbon (1) by a recorder according to one of claims 22 to   48, characterized in that it comprises a thermal transfer ribbon (1), containing spatially recorded data, a receiving medium (19), a device for bringing the pigmented face of the ribbon into contact with the receiving medium and a source   heat induction in the heat transfer ribbon (1) during said contact.   53. Transfer device (22) according to one of claims 51 to 52   characterized in that the heat source comprises heating rollers (21 ') and (21 ") between which is placed the assembly comprising the tape (1) and the support receiver (19).   54. Transfer device (22) according to one of claims 51 to 53   characterized in that the heat source comprises a heating press in   which the assembly comprising the ribbon (1) and the receiver support (19) is placed.